Revision: 937
http://www.exim.org/viewvc/pcre2?view=rev&revision=937
Author: ph10
Date: 2018-06-18 15:03:33 +0100 (Mon, 18 Jun 2018)
Log Message:
-----------
More typos and changes to "Kibibytes" for "Kilobytes".
Modified Paths:
--------------
code/trunk/ChangeLog
code/trunk/HACKING
code/trunk/NON-AUTOTOOLS-BUILD
code/trunk/README
code/trunk/configure.ac
code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt
code/trunk/doc/html/README.txt
code/trunk/doc/html/pcre2_jit_stack_assign.html
code/trunk/doc/html/pcre2_jit_stack_create.html
code/trunk/doc/html/pcre2api.html
code/trunk/doc/html/pcre2build.html
code/trunk/doc/html/pcre2grep.html
code/trunk/doc/html/pcre2jit.html
code/trunk/doc/html/pcre2limits.html
code/trunk/doc/html/pcre2pattern.html
code/trunk/doc/html/pcre2perform.html
code/trunk/doc/pcre2.txt
code/trunk/doc/pcre2_jit_stack_assign.3
code/trunk/doc/pcre2_jit_stack_create.3
code/trunk/doc/pcre2api.3
code/trunk/doc/pcre2build.3
code/trunk/doc/pcre2grep.1
code/trunk/doc/pcre2grep.txt
code/trunk/doc/pcre2jit.3
code/trunk/doc/pcre2limits.3
code/trunk/doc/pcre2pattern.3
code/trunk/doc/pcre2perform.3
code/trunk/src/config.h.generic
code/trunk/src/config.h.in
code/trunk/src/pcre2_dfa_match.c
code/trunk/src/pcre2_internal.h
code/trunk/src/pcre2_match.c
code/trunk/src/pcre2grep.c
code/trunk/testdata/grepinput
code/trunk/testdata/grepoutput
Modified: code/trunk/ChangeLog
===================================================================
--- code/trunk/ChangeLog 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/ChangeLog 2018-06-18 14:03:33 UTC (rev 937)
@@ -370,8 +370,8 @@
31. If more than one of "push", "pushcopy", or "pushtablescopy" were set in
pcre2test, a crash could occur.
-32. Make -bigstack in RunTest allocate a 64MB stack (instead of 16 MB) so that
-all the tests can run with clang's sanitizing options.
+32. Make -bigstack in RunTest allocate a 64MiB stack (instead of 16 MiB) so
+that all the tests can run with clang's sanitizing options.
33. Implement extra compile options in the compile context and add the first
one: PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES.
@@ -964,9 +964,9 @@
40. Fix two clang compiler warnings in pcre2test when only one code unit width
is supported.
-41. Upgrade RunTest to automatically re-run test 2 with a large (64M) stack if
-it fails when running the interpreter with a 16M stack (and if changing the
-stack size via pcre2test is possible). This avoids having to manually set a
+41. Upgrade RunTest to automatically re-run test 2 with a large (64MiB) stack
+if it fails when running the interpreter with a 16MiB stack (and if changing
+the stack size via pcre2test is possible). This avoids having to manually set a
large stack size when testing with clang.
42. Fix register overwite in JIT when SSE2 acceleration is enabled.
Modified: code/trunk/HACKING
===================================================================
--- code/trunk/HACKING 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/HACKING 2018-06-18 14:03:33 UTC (rev 937)
@@ -370,7 +370,7 @@
only be 4. The 8-bit library can be compiled to used 3-byte or 4-byte values,
and the 16-bit library can be compiled to use 4-byte values, though this
impairs performance. Specifing a LINK_SIZE larger than 2 for these libraries is
-necessary only when patterns whose compiled length is greater than 64K code
+necessary only when patterns whose compiled length is greater than 65535 code
units are going to be processed. When a LINK_SIZE value uses more than one code
unit, the most significant unit is first.
Modified: code/trunk/NON-AUTOTOOLS-BUILD
===================================================================
--- code/trunk/NON-AUTOTOOLS-BUILD 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/NON-AUTOTOOLS-BUILD 2018-06-18 14:03:33 UTC (rev 937)
@@ -186,7 +186,7 @@
STACK SIZE IN WINDOWS ENVIRONMENTS
-Prior to release 10.30 the default system stack size of 1MB in some Windows
+Prior to release 10.30 the default system stack size of 1MiB in some Windows
environments caused issues with some tests. This should no longer be the case
for 10.30 and later releases.
Modified: code/trunk/README
===================================================================
--- code/trunk/README 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/README 2018-06-18 14:03:33 UTC (rev 937)
@@ -263,7 +263,7 @@
pcre2_set_heap_limit).
. In the 8-bit library, the default maximum compiled pattern size is around
- 64K bytes. You can increase this by adding --with-link-size=3 to the
+ 64 kibibytes. You can increase this by adding --with-link-size=3 to the
"configure" command. PCRE2 then uses three bytes instead of two for offsets
to different parts of the compiled pattern. In the 16-bit library,
--with-link-size=3 is the same as --with-link-size=4, which (in both
Modified: code/trunk/configure.ac
===================================================================
--- code/trunk/configure.ac 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/configure.ac 2018-06-18 14:03:33 UTC (rev 937)
@@ -706,8 +706,8 @@
AC_DEFINE_UNQUOTED([LINK_SIZE], [$with_link_size], [
The value of LINK_SIZE determines the number of bytes used to store
links as offsets within the compiled regex. The default is 2, which
- allows for compiled patterns up to 64K long. This covers the vast
- majority of cases. However, PCRE2 can also be compiled to use 3 or 4
+ allows for compiled patterns up to 65535 code units long. This covers the
+ vast majority of cases. However, PCRE2 can also be compiled to use 3 or 4
bytes instead. This allows for longer patterns in extreme cases.])
AC_DEFINE_UNQUOTED([PARENS_NEST_LIMIT], [$with_parens_nest_limit], [
Modified: code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt
===================================================================
--- code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/NON-AUTOTOOLS-BUILD.txt 2018-06-18 14:03:33 UTC (rev 937)
@@ -186,7 +186,7 @@
STACK SIZE IN WINDOWS ENVIRONMENTS
-Prior to release 10.30 the default system stack size of 1MB in some Windows
+Prior to release 10.30 the default system stack size of 1MiB in some Windows
environments caused issues with some tests. This should no longer be the case
for 10.30 and later releases.
Modified: code/trunk/doc/html/README.txt
===================================================================
--- code/trunk/doc/html/README.txt 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/README.txt 2018-06-18 14:03:33 UTC (rev 937)
@@ -263,7 +263,7 @@
pcre2_set_heap_limit).
. In the 8-bit library, the default maximum compiled pattern size is around
- 64K bytes. You can increase this by adding --with-link-size=3 to the
+ 64 kibibytes. You can increase this by adding --with-link-size=3 to the
"configure" command. PCRE2 then uses three bytes instead of two for offsets
to different parts of the compiled pattern. In the 16-bit library,
--with-link-size=3 is the same as --with-link-size=4, which (in both
Modified: code/trunk/doc/html/pcre2_jit_stack_assign.html
===================================================================
--- code/trunk/doc/html/pcre2_jit_stack_assign.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2_jit_stack_assign.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -38,7 +38,7 @@
</PRE>
</P>
<P>
-If <i>callback</i> is NULL and <i>callback_data</i> is NULL, an internal 32K
+If <i>callback</i> is NULL and <i>callback_data</i> is NULL, an internal 32KiB
block on the machine stack is used.
</P>
<P>
@@ -49,8 +49,9 @@
<P>
If <i>callback</i> not NULL, it is called with <i>callback_data</i> as an
argument at the start of matching, in order to set up a JIT stack. If the
-result is NULL, the internal 32K stack is used; otherwise the return value must
-be a valid JIT stack, the result of calling <b>pcre2_jit_stack_create()</b>.
+result is NULL, the internal 32KiB stack is used; otherwise the return value
+must be a valid JIT stack, the result of calling
+<b>pcre2_jit_stack_create()</b>.
</P>
<P>
You may safely use the same JIT stack for multiple patterns, as long as they
Modified: code/trunk/doc/html/pcre2_jit_stack_create.html
===================================================================
--- code/trunk/doc/html/pcre2_jit_stack_create.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2_jit_stack_create.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -33,8 +33,8 @@
allocation. The result can be passed to the JIT run-time code by calling
<b>pcre2_jit_stack_assign()</b> to associate the stack with a compiled pattern,
which can then be processed by <b>pcre2_match()</b> or <b>pcre2_jit_match()</b>.
-A maximum stack size of 512K to 1M should be more than enough for any pattern.
-For more details, see the
+A maximum stack size of 512KiB to 1MiB should be more than enough for any
+pattern. For more details, see the
<a href="pcre2jit.html"><b>pcre2jit</b></a>
page.
</P>
Modified: code/trunk/doc/html/pcre2api.html
===================================================================
--- code/trunk/doc/html/pcre2api.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2api.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -973,7 +973,7 @@
limit is set, less than the default.
</P>
<P>
-The <b>pcre2_match()</b> function starts out using a 20K vector on the system
+The <b>pcre2_match()</b> function starts out using a 20KiB vector on the system
stack for recording backtracking points. The more nested backtracking points
there are (that is, the deeper the search tree), the more memory is needed.
Heap memory is used only if the initial vector is too small. If the heap limit
@@ -1155,7 +1155,7 @@
<P>
The default value of 2 for the 8-bit and 16-bit libraries is sufficient for all
but the most massive patterns, since it allows the size of the compiled pattern
-to be up to 64K code units. Larger values allow larger regular expressions to
+to be up to 65535 code units. Larger values allow larger regular expressions to
be compiled by those two libraries, but at the expense of slower matching.
<pre>
PCRE2_CONFIG_MATCHLIMIT
Modified: code/trunk/doc/html/pcre2build.html
===================================================================
--- code/trunk/doc/html/pcre2build.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2build.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -252,10 +252,10 @@
another (for example, from an opening parenthesis to an alternation
metacharacter). By default, in the 8-bit and 16-bit libraries, two-byte values
are used for these offsets, leading to a maximum size for a compiled pattern of
-around 64K code units. This is sufficient to handle all but the most gigantic
-patterns. Nevertheless, some people do want to process truly enormous patterns,
-so it is possible to compile PCRE2 to use three-byte or four-byte offsets by
-adding a setting such as
+around 64 thousand code units. This is sufficient to handle all but the most
+gigantic patterns. Nevertheless, some people do want to process truly enormous
+patterns, so it is possible to compile PCRE2 to use three-byte or four-byte
+offsets by adding a setting such as
<pre>
--with-link-size=3
</pre>
@@ -282,7 +282,7 @@
counting is done differently).
</P>
<P>
-The <b>pcre2_match()</b> function starts out using a 20K vector on the system
+The <b>pcre2_match()</b> function starts out using a 20KiB vector on the system
stack to record backtracking points. The more nested backtracking points there
are (that is, the deeper the search tree), the more memory is needed. If the
initial vector is not large enough, heap memory is used, up to a certain limit,
@@ -399,13 +399,13 @@
<P>
<b>pcre2grep</b> uses an internal buffer to hold a "window" on the file it is
scanning, in order to be able to output "before" and "after" lines when it
-finds a match. The starting size of the buffer is controlled by a parameter
-whose default value is 20K. The buffer itself is three times this size, but
-because of the way it is used for holding "before" lines, the longest line that
-is guaranteed to be processable is the parameter size. If a longer line is
-encountered, <b>pcre2grep</b> automatically expands the buffer, up to a
-specified maximum size, whose default is 1M or the starting size, whichever is
-the larger. You can change the default parameter values by adding, for example,
+finds a match. The default starting size of the buffer is 20KiB. The buffer
+itself is three times this size, but because of the way it is used for holding
+"before" lines, the longest line that is guaranteed to be processable is the
+notional buffer size. If a longer line is encountered, <b>pcre2grep</b>
+automatically expands the buffer, up to a specified maximum size, whose default
+is 1MiB or the starting size, whichever is the larger. You can change the
+default parameter values by adding, for example,
<pre>
--with-pcre2grep-bufsize=51200
--with-pcre2grep-max-bufsize=2097152
Modified: code/trunk/doc/html/pcre2grep.html
===================================================================
--- code/trunk/doc/html/pcre2grep.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2grep.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -87,7 +87,7 @@
long lines, a larger buffer may be needed; this is handled by automatically
extending the buffer, up to the limit specified by <b>--max-buffer-size</b>. The
default values for these parameters can be set when <b>pcre2grep</b> is
-built; if nothing is specified, the defaults are set to 20K and 1M
+built; if nothing is specified, the defaults are set to 20KiB and 1MiB
respectively. An error occurs if a line is too long and the buffer can no
longer be expanded.
</P>
@@ -97,7 +97,7 @@
small, fewer than requested "before" and "after" lines may be output.
</P>
<P>
-Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater.
+Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the greater.
BUFSIZ is defined in <b><stdio.h></b>. When there is more than one pattern
(specified by the use of <b>-e</b> and/or <b>-f</b>), each pattern is applied to
each line in the order in which they are defined, except that all the <b>-e</b>
Modified: code/trunk/doc/html/pcre2jit.html
===================================================================
--- code/trunk/doc/html/pcre2jit.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2jit.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -179,7 +179,7 @@
<br><a name="SEC6" href="#TOC1">CONTROLLING THE JIT STACK</a><br>
<P>
When the compiled JIT code runs, it needs a block of memory to use as a stack.
-By default, it uses 32K on the machine stack. However, some large or
+By default, it uses 32KiB on the machine stack. However, some large or
complicated patterns need more than this. The error PCRE2_ERROR_JIT_STACKLIMIT
is given when there is not enough stack. Three functions are provided for
managing blocks of memory for use as JIT stacks. There is further discussion
@@ -194,8 +194,8 @@
pointer to an opaque structure of type <b>pcre2_jit_stack</b>, or NULL if there
is an error. The <b>pcre2_jit_stack_free()</b> function is used to free a stack
that is no longer needed. (For the technically minded: the address space is
-allocated by mmap or VirtualAlloc.) A maximum stack size of 512K to 1M should
-be more than enough for any pattern.
+allocated by mmap or VirtualAlloc.) A maximum stack size of 512KiB to 1MiB
+should be more than enough for any pattern.
</P>
<P>
The <b>pcre2_jit_stack_assign()</b> function specifies which stack JIT code
@@ -209,7 +209,7 @@
passed to a matching function, its information determines which JIT stack is
used. There are three cases for the values of the other two options:
<pre>
- (1) If <i>callback</i> is NULL and <i>data</i> is NULL, an internal 32K block
+ (1) If <i>callback</i> is NULL and <i>data</i> is NULL, an internal 32KiB block
on the machine stack is used. This is the default when a match
context is created.
@@ -220,7 +220,7 @@
(3) If <i>callback</i> is not NULL, it must point to a function that is
called with <i>data</i> as an argument at the start of matching, in
order to set up a JIT stack. If the return from the callback
- function is NULL, the internal 32K stack is used; otherwise the
+ function is NULL, the internal 32KiB stack is used; otherwise the
return value must be a valid JIT stack, the result of calling
<b>pcre2_jit_stack_create()</b>.
</pre>
@@ -286,9 +286,9 @@
Modern operating systems have a nice feature: they can reserve an address space
instead of allocating memory. We can safely allocate memory pages inside this
address space, so the stack could grow without moving memory data (this is
-important because of pointers). Thus we can allocate 1M address space, and use
-only a single memory page (usually 4K) if that is enough. However, we can still
-grow up to 1M anytime if needed.
+important because of pointers). Thus we can allocate 1MiB address space, and
+use only a single memory page (usually 4KiB) if that is enough. However, we can
+still grow up to 1MiB anytime if needed.
</P>
<P>
(3) Who "owns" a JIT stack?
@@ -328,7 +328,7 @@
</P>
<P>
(6) OK, the stack is for long term memory allocation. But what happens if a
-pattern causes stack overflow with a stack of 1M? Is that 1M kept until the
+pattern causes stack overflow with a stack of 1MiB? Is that 1MiB kept until the
stack is freed?
<br>
<br>
Modified: code/trunk/doc/html/pcre2limits.html
===================================================================
--- code/trunk/doc/html/pcre2limits.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2limits.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -20,12 +20,12 @@
in practice be relevant.
</P>
<P>
-The maximum size of a compiled pattern is approximately 64K code units for the
-8-bit and 16-bit libraries if PCRE2 is compiled with the default internal
-linkage size, which is 2 bytes for these libraries. If you want to process
-regular expressions that are truly enormous, you can compile PCRE2 with an
-internal linkage size of 3 or 4 (when building the 16-bit library, 3 is rounded
-up to 4). See the <b>README</b> file in the source distribution and the
+The maximum size of a compiled pattern is approximately 64 thousand code units
+for the 8-bit and 16-bit libraries if PCRE2 is compiled with the default
+internal linkage size, which is 2 bytes for these libraries. If you want to
+process regular expressions that are truly enormous, you can compile PCRE2 with
+an internal linkage size of 3 or 4 (when building the 16-bit library, 3 is
+rounded up to 4). See the <b>README</b> file in the source distribution and the
<a href="pcre2build.html"><b>pcre2build</b></a>
documentation for details. In these cases the limit is substantially larger.
However, the speed of execution is slower. In the 32-bit library, the internal
Modified: code/trunk/doc/html/pcre2pattern.html
===================================================================
--- code/trunk/doc/html/pcre2pattern.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2pattern.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -549,7 +549,7 @@
<P>
The sequence \g followed by a signed or unsigned number, optionally enclosed
in braces, is an absolute or relative backreference. A named backreference
-can be coded as \g{name}. backreferences are discussed
+can be coded as \g{name}. Backreferences are discussed
<a href="#backreferences">later,</a>
following the discussion of
<a href="#subpattern">parenthesized subpatterns.</a>
@@ -2247,7 +2247,7 @@
minimum of zero.
</P>
<P>
-backreferences of this type cause the group that they reference to be treated
+Backreferences of this type cause the group that they reference to be treated
as an
<a href="#atomicgroup">atomic group.</a>
Once the whole group has been matched, a subsequent matching failure cannot
Modified: code/trunk/doc/html/pcre2perform.html
===================================================================
--- code/trunk/doc/html/pcre2perform.html 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/html/pcre2perform.html 2018-06-18 14:03:33 UTC (rev 937)
@@ -52,9 +52,9 @@
<pre>
((ab){1,1000}c){1,3}
</pre>
-uses over 50K bytes when compiled using the 8-bit library. When PCRE2 is
+uses over 50KiB when compiled using the 8-bit library. When PCRE2 is
compiled with its default internal pointer size of two bytes, the size limit on
-a compiled pattern is 64K code units in the 8-bit and 16-bit libraries, and
+a compiled pattern is 65535 code units in the 8-bit and 16-bit libraries, and
this is reached with the above pattern if the outer repetition is increased
from 3 to 4. PCRE2 can be compiled to use larger internal pointers and thus
handle larger compiled patterns, but it is better to try to rewrite your
@@ -68,14 +68,14 @@
<pre>
((ab)(?2){0,999}c)(?1){0,2}
</pre>
-reduces the memory requirements to around 16K, and indeed it remains under 20K
-even with the outer repetition increased to 100. However, this kind of pattern
-is not always exactly equivalent, because any captures within subroutine calls
-are lost when the subroutine completes. If this is not a problem, this kind of
-rewriting will allow you to process patterns that PCRE2 cannot otherwise
-handle. The matching performance of the two different versions of the pattern
-are roughly the same. (This applies from release 10.30 - things were different
-in earlier releases.)
+reduces the memory requirements to around 16KiB, and indeed it remains under
+20KiB even with the outer repetition increased to 100. However, this kind of
+pattern is not always exactly equivalent, because any captures within
+subroutine calls are lost when the subroutine completes. If this is not a
+problem, this kind of rewriting will allow you to process patterns that PCRE2
+cannot otherwise handle. The matching performance of the two different versions
+of the pattern are roughly the same. (This applies from release 10.30 - things
+were different in earlier releases.)
</P>
<br><a name="SEC3" href="#TOC1">STACK AND HEAP USAGE AT RUN TIME</a><br>
<P>
@@ -83,7 +83,7 @@
uses very little system stack at run time. In earlier releases recursive
function calls could use a great deal of stack, and this could cause problems,
but this usage has been eliminated. Backtracking positions are now explicitly
-remembered in memory frames controlled by the code. An initial 20K vector of
+remembered in memory frames controlled by the code. An initial 20KiB vector of
frames is allocated on the system stack (enough for about 100 frames for small
patterns), but if this is insufficient, heap memory is used. The amount of heap
memory can be limited; if the limit is set to zero, only the initial stack
Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2.txt 2018-06-18 14:03:33 UTC (rev 937)
@@ -979,51 +979,52 @@
unless ddd is less than the limit set by the caller of pcre2_match()
or, if no such limit is set, less than the default.
- The pcre2_match() function starts out using a 20K vector on the system
- stack for recording backtracking points. The more nested backtracking
- points there are (that is, the deeper the search tree), the more memory
- is needed. Heap memory is used only if the initial vector is too
- small. If the heap limit is set to a value less than 21 (in particular,
- zero) no heap memory will be used. In this case, only patterns that do
- not have a lot of nested backtracking can be successfully processed.
+ The pcre2_match() function starts out using a 20KiB vector on the sys-
+ tem stack for recording backtracking points. The more nested backtrack-
+ ing points there are (that is, the deeper the search tree), the more
+ memory is needed. Heap memory is used only if the initial vector is
+ too small. If the heap limit is set to a value less than 21 (in partic-
+ ular, zero) no heap memory will be used. In this case, only patterns
+ that do not have a lot of nested backtracking can be successfully pro-
+ cessed.
- Similarly, for pcre2_dfa_match(), a vector on the system stack is used
- when processing pattern recursions, lookarounds, or atomic groups, and
- only if this is not big enough is heap memory used. In this case, too,
+ Similarly, for pcre2_dfa_match(), a vector on the system stack is used
+ when processing pattern recursions, lookarounds, or atomic groups, and
+ only if this is not big enough is heap memory used. In this case, too,
setting a value of zero disables the use of the heap.
int pcre2_set_match_limit(pcre2_match_context *mcontext,
uint32_t value);
- The match_limit parameter provides a means of preventing PCRE2 from
+ The match_limit parameter provides a means of preventing PCRE2 from
using up too many computing resources when processing patterns that are
not going to match, but which have a very large number of possibilities
- in their search trees. The classic example is a pattern that uses
+ in their search trees. The classic example is a pattern that uses
nested unlimited repeats.
- There is an internal counter in pcre2_match() that is incremented each
- time round its main matching loop. If this value reaches the match
+ There is an internal counter in pcre2_match() that is incremented each
+ time round its main matching loop. If this value reaches the match
limit, pcre2_match() returns the negative value PCRE2_ERROR_MATCHLIMIT.
- This has the effect of limiting the amount of backtracking that can
+ This has the effect of limiting the amount of backtracking that can
take place. For patterns that are not anchored, the count restarts from
- zero for each position in the subject string. This limit also applies
+ zero for each position in the subject string. This limit also applies
to pcre2_dfa_match(), though the counting is done in a different way.
- When pcre2_match() is called with a pattern that was successfully pro-
+ When pcre2_match() is called with a pattern that was successfully pro-
cessed by pcre2_jit_compile(), the way in which matching is executed is
- entirely different. However, there is still the possibility of runaway
- matching that goes on for a very long time, and so the match_limit
- value is also used in this case (but in a different way) to limit how
+ entirely different. However, there is still the possibility of runaway
+ matching that goes on for a very long time, and so the match_limit
+ value is also used in this case (but in a different way) to limit how
long the matching can continue.
- The default value for the limit can be set when PCRE2 is built; the
- default default is 10 million, which handles all but the most extreme
- cases. A value for the match limit may also be supplied by an item at
+ The default value for the limit can be set when PCRE2 is built; the
+ default default is 10 million, which handles all but the most extreme
+ cases. A value for the match limit may also be supplied by an item at
the start of a pattern of the form
(*LIMIT_MATCH=ddd)
- where ddd is a decimal number. However, such a setting is ignored
+ where ddd is a decimal number. However, such a setting is ignored
unless ddd is less than the limit set by the caller of pcre2_match() or
pcre2_dfa_match() or, if no such limit is set, less than the default.
@@ -1030,44 +1031,44 @@
int pcre2_set_depth_limit(pcre2_match_context *mcontext,
uint32_t value);
- This parameter limits the depth of nested backtracking in
- pcre2_match(). Each time a nested backtracking point is passed, a new
+ This parameter limits the depth of nested backtracking in
+ pcre2_match(). Each time a nested backtracking point is passed, a new
memory "frame" is used to remember the state of matching at that point.
- Thus, this parameter indirectly limits the amount of memory that is
- used in a match. However, because the size of each memory "frame"
+ Thus, this parameter indirectly limits the amount of memory that is
+ used in a match. However, because the size of each memory "frame"
depends on the number of capturing parentheses, the actual memory limit
- varies from pattern to pattern. This limit was more useful in versions
+ varies from pattern to pattern. This limit was more useful in versions
before 10.30, where function recursion was used for backtracking.
- The depth limit is not relevant, and is ignored, when matching is done
+ The depth limit is not relevant, and is ignored, when matching is done
using JIT compiled code. However, it is supported by pcre2_dfa_match(),
- which uses it to limit the depth of nested internal recursive function
- calls that implement atomic groups, lookaround assertions, and pattern
+ which uses it to limit the depth of nested internal recursive function
+ calls that implement atomic groups, lookaround assertions, and pattern
recursions. This limits, indirectly, the amount of system stack that is
- used. It was more useful in versions before 10.32, when stack memory
+ used. It was more useful in versions before 10.32, when stack memory
was used for local workspace vectors for recursive function calls. From
- version 10.32, only local variables are allocated on the stack and as
+ version 10.32, only local variables are allocated on the stack and as
each call uses only a few hundred bytes, even a small stack can support
quite a lot of recursion.
- If the depth of internal recursive function calls is great enough,
- local workspace vectors are allocated on the heap from version 10.32
- onwards, so the depth limit also indirectly limits the amount of heap
+ If the depth of internal recursive function calls is great enough,
+ local workspace vectors are allocated on the heap from version 10.32
+ onwards, so the depth limit also indirectly limits the amount of heap
memory that is used. A recursive pattern such as /(.(?2))((?1)|)/, when
- matched to a very long string using pcre2_dfa_match(), can use a great
- deal of memory. However, it is probably better to limit heap usage
+ matched to a very long string using pcre2_dfa_match(), can use a great
+ deal of memory. However, it is probably better to limit heap usage
directly by calling pcre2_set_heap_limit().
- The default value for the depth limit can be set when PCRE2 is built;
- if it is not, the default is set to the same value as the default for
- the match limit. If the limit is exceeded, pcre2_match() or
+ The default value for the depth limit can be set when PCRE2 is built;
+ if it is not, the default is set to the same value as the default for
+ the match limit. If the limit is exceeded, pcre2_match() or
pcre2_dfa_match() returns PCRE2_ERROR_DEPTHLIMIT. A value for the depth
- limit may also be supplied by an item at the start of a pattern of the
+ limit may also be supplied by an item at the start of a pattern of the
form
(*LIMIT_DEPTH=ddd)
- where ddd is a decimal number. However, such a setting is ignored
+ where ddd is a decimal number. However, such a setting is ignored
unless ddd is less than the limit set by the caller of pcre2_match() or
pcre2_dfa_match() or, if no such limit is set, less than the default.
@@ -1076,96 +1077,96 @@
int pcre2_config(uint32_t what, void *where);
- The function pcre2_config() makes it possible for a PCRE2 client to
- discover which optional features have been compiled into the PCRE2
- library. The pcre2build documentation has more details about these
+ The function pcre2_config() makes it possible for a PCRE2 client to
+ discover which optional features have been compiled into the PCRE2
+ library. The pcre2build documentation has more details about these
optional features.
- The first argument for pcre2_config() specifies which information is
- required. The second argument is a pointer to memory into which the
- information is placed. If NULL is passed, the function returns the
- amount of memory that is needed for the requested information. For
- calls that return numerical values, the value is in bytes; when
- requesting these values, where should point to appropriately aligned
- memory. For calls that return strings, the required length is given in
+ The first argument for pcre2_config() specifies which information is
+ required. The second argument is a pointer to memory into which the
+ information is placed. If NULL is passed, the function returns the
+ amount of memory that is needed for the requested information. For
+ calls that return numerical values, the value is in bytes; when
+ requesting these values, where should point to appropriately aligned
+ memory. For calls that return strings, the required length is given in
code units, not counting the terminating zero.
- When requesting information, the returned value from pcre2_config() is
- non-negative on success, or the negative error code PCRE2_ERROR_BADOP-
- TION if the value in the first argument is not recognized. The follow-
+ When requesting information, the returned value from pcre2_config() is
+ non-negative on success, or the negative error code PCRE2_ERROR_BADOP-
+ TION if the value in the first argument is not recognized. The follow-
ing information is available:
PCRE2_CONFIG_BSR
- The output is a uint32_t integer whose value indicates what character
- sequences the \R escape sequence matches by default. A value of
+ The output is a uint32_t integer whose value indicates what character
+ sequences the \R escape sequence matches by default. A value of
PCRE2_BSR_UNICODE means that \R matches any Unicode line ending
- sequence; a value of PCRE2_BSR_ANYCRLF means that \R matches only CR,
+ sequence; a value of PCRE2_BSR_ANYCRLF means that \R matches only CR,
LF, or CRLF. The default can be overridden when a pattern is compiled.
PCRE2_CONFIG_COMPILED_WIDTHS
- The output is a uint32_t integer whose lower bits indicate which code
- unit widths were selected when PCRE2 was built. The 1-bit indicates
- 8-bit support, and the 2-bit and 4-bit indicate 16-bit and 32-bit sup-
+ The output is a uint32_t integer whose lower bits indicate which code
+ unit widths were selected when PCRE2 was built. The 1-bit indicates
+ 8-bit support, and the 2-bit and 4-bit indicate 16-bit and 32-bit sup-
port, respectively.
PCRE2_CONFIG_DEPTHLIMIT
- The output is a uint32_t integer that gives the default limit for the
- depth of nested backtracking in pcre2_match() or the depth of nested
- recursions, lookarounds, and atomic groups in pcre2_dfa_match(). Fur-
+ The output is a uint32_t integer that gives the default limit for the
+ depth of nested backtracking in pcre2_match() or the depth of nested
+ recursions, lookarounds, and atomic groups in pcre2_dfa_match(). Fur-
ther details are given with pcre2_set_depth_limit() above.
PCRE2_CONFIG_HEAPLIMIT
- The output is a uint32_t integer that gives, in kibibytes, the default
- limit for the amount of heap memory used by pcre2_match() or
- pcre2_dfa_match(). Further details are given with
+ The output is a uint32_t integer that gives, in kibibytes, the default
+ limit for the amount of heap memory used by pcre2_match() or
+ pcre2_dfa_match(). Further details are given with
pcre2_set_heap_limit() above.
PCRE2_CONFIG_JIT
- The output is a uint32_t integer that is set to one if support for
+ The output is a uint32_t integer that is set to one if support for
just-in-time compiling is available; otherwise it is set to zero.
PCRE2_CONFIG_JITTARGET
- The where argument should point to a buffer that is at least 48 code
- units long. (The exact length required can be found by calling
- pcre2_config() with where set to NULL.) The buffer is filled with a
- string that contains the name of the architecture for which the JIT
- compiler is configured, for example "x86 32bit (little endian +
- unaligned)". If JIT support is not available, PCRE2_ERROR_BADOPTION is
- returned, otherwise the number of code units used is returned. This is
+ The where argument should point to a buffer that is at least 48 code
+ units long. (The exact length required can be found by calling
+ pcre2_config() with where set to NULL.) The buffer is filled with a
+ string that contains the name of the architecture for which the JIT
+ compiler is configured, for example "x86 32bit (little endian +
+ unaligned)". If JIT support is not available, PCRE2_ERROR_BADOPTION is
+ returned, otherwise the number of code units used is returned. This is
the length of the string, plus one unit for the terminating zero.
PCRE2_CONFIG_LINKSIZE
The output is a uint32_t integer that contains the number of bytes used
- for internal linkage in compiled regular expressions. When PCRE2 is
- configured, the value can be set to 2, 3, or 4, with the default being
- 2. This is the value that is returned by pcre2_config(). However, when
- the 16-bit library is compiled, a value of 3 is rounded up to 4, and
- when the 32-bit library is compiled, internal linkages always use 4
+ for internal linkage in compiled regular expressions. When PCRE2 is
+ configured, the value can be set to 2, 3, or 4, with the default being
+ 2. This is the value that is returned by pcre2_config(). However, when
+ the 16-bit library is compiled, a value of 3 is rounded up to 4, and
+ when the 32-bit library is compiled, internal linkages always use 4
bytes, so the configured value is not relevant.
The default value of 2 for the 8-bit and 16-bit libraries is sufficient
- for all but the most massive patterns, since it allows the size of the
- compiled pattern to be up to 64K code units. Larger values allow larger
- regular expressions to be compiled by those two libraries, but at the
- expense of slower matching.
+ for all but the most massive patterns, since it allows the size of the
+ compiled pattern to be up to 65535 code units. Larger values allow
+ larger regular expressions to be compiled by those two libraries, but
+ at the expense of slower matching.
PCRE2_CONFIG_MATCHLIMIT
The output is a uint32_t integer that gives the default match limit for
- pcre2_match(). Further details are given with pcre2_set_match_limit()
+ pcre2_match(). Further details are given with pcre2_set_match_limit()
above.
PCRE2_CONFIG_NEWLINE
- The output is a uint32_t integer whose value specifies the default
- character sequence that is recognized as meaning "newline". The values
+ The output is a uint32_t integer whose value specifies the default
+ character sequence that is recognized as meaning "newline". The values
are:
PCRE2_NEWLINE_CR Carriage return (CR)
@@ -1175,23 +1176,23 @@
PCRE2_NEWLINE_ANYCRLF Any of CR, LF, or CRLF
PCRE2_NEWLINE_NUL The NUL character (binary zero)
- The default should normally correspond to the standard sequence for
+ The default should normally correspond to the standard sequence for
your operating system.
PCRE2_CONFIG_NEVER_BACKSLASH_C
- The output is a uint32_t integer that is set to one if the use of \C
- was permanently disabled when PCRE2 was built; otherwise it is set to
+ The output is a uint32_t integer that is set to one if the use of \C
+ was permanently disabled when PCRE2 was built; otherwise it is set to
zero.
PCRE2_CONFIG_PARENSLIMIT
- The output is a uint32_t integer that gives the maximum depth of nest-
+ The output is a uint32_t integer that gives the maximum depth of nest-
ing of parentheses (of any kind) in a pattern. This limit is imposed to
- cap the amount of system stack used when a pattern is compiled. It is
- specified when PCRE2 is built; the default is 250. This limit does not
- take into account the stack that may already be used by the calling
- application. For finer control over compilation stack usage, see
+ cap the amount of system stack used when a pattern is compiled. It is
+ specified when PCRE2 is built; the default is 250. This limit does not
+ take into account the stack that may already be used by the calling
+ application. For finer control over compilation stack usage, see
pcre2_set_compile_recursion_guard().
PCRE2_CONFIG_STACKRECURSE
@@ -1201,25 +1202,25 @@
PCRE2_CONFIG_UNICODE_VERSION
- The where argument should point to a buffer that is at least 24 code
- units long. (The exact length required can be found by calling
- pcre2_config() with where set to NULL.) If PCRE2 has been compiled
- without Unicode support, the buffer is filled with the text "Unicode
- not supported". Otherwise, the Unicode version string (for example,
- "8.0.0") is inserted. The number of code units used is returned. This
+ The where argument should point to a buffer that is at least 24 code
+ units long. (The exact length required can be found by calling
+ pcre2_config() with where set to NULL.) If PCRE2 has been compiled
+ without Unicode support, the buffer is filled with the text "Unicode
+ not supported". Otherwise, the Unicode version string (for example,
+ "8.0.0") is inserted. The number of code units used is returned. This
is the length of the string plus one unit for the terminating zero.
PCRE2_CONFIG_UNICODE
- The output is a uint32_t integer that is set to one if Unicode support
- is available; otherwise it is set to zero. Unicode support implies UTF
+ The output is a uint32_t integer that is set to one if Unicode support
+ is available; otherwise it is set to zero. Unicode support implies UTF
support.
PCRE2_CONFIG_VERSION
- The where argument should point to a buffer that is at least 24 code
- units long. (The exact length required can be found by calling
- pcre2_config() with where set to NULL.) The buffer is filled with the
+ The where argument should point to a buffer that is at least 24 code
+ units long. (The exact length required can be found by calling
+ pcre2_config() with where set to NULL.) The buffer is filled with the
PCRE2 version string, zero-terminated. The number of code units used is
returned. This is the length of the string plus one unit for the termi-
nating zero.
@@ -1237,96 +1238,96 @@
pcre2_code *pcre2_code_copy_with_tables(const pcre2_code *code);
- The pcre2_compile() function compiles a pattern into an internal form.
- The pattern is defined by a pointer to a string of code units and a
- length (in code units). If the pattern is zero-terminated, the length
- can be specified as PCRE2_ZERO_TERMINATED. The function returns a
- pointer to a block of memory that contains the compiled pattern and
+ The pcre2_compile() function compiles a pattern into an internal form.
+ The pattern is defined by a pointer to a string of code units and a
+ length (in code units). If the pattern is zero-terminated, the length
+ can be specified as PCRE2_ZERO_TERMINATED. The function returns a
+ pointer to a block of memory that contains the compiled pattern and
related data, or NULL if an error occurred.
- If the compile context argument ccontext is NULL, memory for the com-
- piled pattern is obtained by calling malloc(). Otherwise, it is
- obtained from the same memory function that was used for the compile
- context. The caller must free the memory by calling pcre2_code_free()
+ If the compile context argument ccontext is NULL, memory for the com-
+ piled pattern is obtained by calling malloc(). Otherwise, it is
+ obtained from the same memory function that was used for the compile
+ context. The caller must free the memory by calling pcre2_code_free()
when it is no longer needed.
The function pcre2_code_copy() makes a copy of the compiled code in new
- memory, using the same memory allocator as was used for the original.
- However, if the code has been processed by the JIT compiler (see
- below), the JIT information cannot be copied (because it is position-
+ memory, using the same memory allocator as was used for the original.
+ However, if the code has been processed by the JIT compiler (see
+ below), the JIT information cannot be copied (because it is position-
dependent). The new copy can initially be used only for non-JIT match-
ing, though it can be passed to pcre2_jit_compile() if required.
The pcre2_code_copy() function provides a way for individual threads in
- a multithreaded application to acquire a private copy of shared com-
- piled code. However, it does not make a copy of the character tables
- used by the compiled pattern; the new pattern code points to the same
- tables as the original code. (See "Locale Support" below for details
- of these character tables.) In many applications the same tables are
- used throughout, so this behaviour is appropriate. Nevertheless, there
+ a multithreaded application to acquire a private copy of shared com-
+ piled code. However, it does not make a copy of the character tables
+ used by the compiled pattern; the new pattern code points to the same
+ tables as the original code. (See "Locale Support" below for details
+ of these character tables.) In many applications the same tables are
+ used throughout, so this behaviour is appropriate. Nevertheless, there
are occasions when a copy of a compiled pattern and the relevant tables
- are needed. The pcre2_code_copy_with_tables() provides this facility.
- Copies of both the code and the tables are made, with the new code
- pointing to the new tables. The memory for the new tables is automati-
- cally freed when pcre2_code_free() is called for the new copy of the
+ are needed. The pcre2_code_copy_with_tables() provides this facility.
+ Copies of both the code and the tables are made, with the new code
+ pointing to the new tables. The memory for the new tables is automati-
+ cally freed when pcre2_code_free() is called for the new copy of the
compiled code.
- NOTE: When one of the matching functions is called, pointers to the
+ NOTE: When one of the matching functions is called, pointers to the
compiled pattern and the subject string are set in the match data block
- so that they can be referenced by the substring extraction functions.
- After running a match, you must not free a compiled pattern (or a sub-
- ject string) until after all operations on the match data block have
+ so that they can be referenced by the substring extraction functions.
+ After running a match, you must not free a compiled pattern (or a sub-
+ ject string) until after all operations on the match data block have
taken place.
- The options argument for pcre2_compile() contains various bit settings
- that affect the compilation. It should be zero if no options are
- required. The available options are described below. Some of them (in
- particular, those that are compatible with Perl, but some others as
- well) can also be set and unset from within the pattern (see the
+ The options argument for pcre2_compile() contains various bit settings
+ that affect the compilation. It should be zero if no options are
+ required. The available options are described below. Some of them (in
+ particular, those that are compatible with Perl, but some others as
+ well) can also be set and unset from within the pattern (see the
detailed description in the pcre2pattern documentation).
- For those options that can be different in different parts of the pat-
- tern, the contents of the options argument specifies their settings at
- the start of compilation. The PCRE2_ANCHORED, PCRE2_ENDANCHORED, and
- PCRE2_NO_UTF_CHECK options can be set at the time of matching as well
+ For those options that can be different in different parts of the pat-
+ tern, the contents of the options argument specifies their settings at
+ the start of compilation. The PCRE2_ANCHORED, PCRE2_ENDANCHORED, and
+ PCRE2_NO_UTF_CHECK options can be set at the time of matching as well
as at compile time.
- Other, less frequently required compile-time parameters (for example,
+ Other, less frequently required compile-time parameters (for example,
the newline setting) can be provided in a compile context (as described
above).
If errorcode or erroroffset is NULL, pcre2_compile() returns NULL imme-
- diately. Otherwise, the variables to which these point are set to an
- error code and an offset (number of code units) within the pattern,
- respectively, when pcre2_compile() returns NULL because a compilation
+ diately. Otherwise, the variables to which these point are set to an
+ error code and an offset (number of code units) within the pattern,
+ respectively, when pcre2_compile() returns NULL because a compilation
error has occurred. The values are not defined when compilation is suc-
cessful and pcre2_compile() returns a non-NULL value.
- There are nearly 100 positive error codes that pcre2_compile() may
- return if it finds an error in the pattern. There are also some nega-
- tive error codes that are used for invalid UTF strings. These are the
+ There are nearly 100 positive error codes that pcre2_compile() may
+ return if it finds an error in the pattern. There are also some nega-
+ tive error codes that are used for invalid UTF strings. These are the
same as given by pcre2_match() and pcre2_dfa_match(), and are described
- in the pcre2unicode page. There is no separate documentation for the
- positive error codes, because the textual error messages that are
- obtained by calling the pcre2_get_error_message() function (see
- "Obtaining a textual error message" below) should be self-explanatory.
- Macro names starting with PCRE2_ERROR_ are defined for both positive
+ in the pcre2unicode page. There is no separate documentation for the
+ positive error codes, because the textual error messages that are
+ obtained by calling the pcre2_get_error_message() function (see
+ "Obtaining a textual error message" below) should be self-explanatory.
+ Macro names starting with PCRE2_ERROR_ are defined for both positive
and negative error codes in pcre2.h.
The value returned in erroroffset is an indication of where in the pat-
- tern the error occurred. It is not necessarily the furthest point in
- the pattern that was read. For example, after the error "lookbehind
+ tern the error occurred. It is not necessarily the furthest point in
+ the pattern that was read. For example, after the error "lookbehind
assertion is not fixed length", the error offset points to the start of
- the failing assertion. For an invalid UTF-8 or UTF-16 string, the off-
+ the failing assertion. For an invalid UTF-8 or UTF-16 string, the off-
set is that of the first code unit of the failing character.
- Some errors are not detected until the whole pattern has been scanned;
- in these cases, the offset passed back is the length of the pattern.
- Note that the offset is in code units, not characters, even in a UTF
+ Some errors are not detected until the whole pattern has been scanned;
+ in these cases, the offset passed back is the length of the pattern.
+ Note that the offset is in code units, not characters, even in a UTF
mode. It may sometimes point into the middle of a UTF-8 or UTF-16 char-
acter.
- This code fragment shows a typical straightforward call to pcre2_com-
+ This code fragment shows a typical straightforward call to pcre2_com-
pile():
pcre2_code *re;
@@ -1340,28 +1341,28 @@
&erroffset, /* for error offset */
NULL); /* no compile context */
- The following names for option bits are defined in the pcre2.h header
+ The following names for option bits are defined in the pcre2.h header
file:
PCRE2_ANCHORED
If this bit is set, the pattern is forced to be "anchored", that is, it
- is constrained to match only at the first matching point in the string
- that is being searched (the "subject string"). This effect can also be
- achieved by appropriate constructs in the pattern itself, which is the
+ is constrained to match only at the first matching point in the string
+ that is being searched (the "subject string"). This effect can also be
+ achieved by appropriate constructs in the pattern itself, which is the
only way to do it in Perl.
PCRE2_ALLOW_EMPTY_CLASS
- By default, for compatibility with Perl, a closing square bracket that
- immediately follows an opening one is treated as a data character for
- the class. When PCRE2_ALLOW_EMPTY_CLASS is set, it terminates the
+ By default, for compatibility with Perl, a closing square bracket that
+ immediately follows an opening one is treated as a data character for
+ the class. When PCRE2_ALLOW_EMPTY_CLASS is set, it terminates the
class, which therefore contains no characters and so can never match.
PCRE2_ALT_BSUX
- This option request alternative handling of three escape sequences,
- which makes PCRE2's behaviour more like ECMAscript (aka JavaScript).
+ This option request alternative handling of three escape sequences,
+ which makes PCRE2's behaviour more like ECMAscript (aka JavaScript).
When it is set:
(1) \U matches an upper case "U" character; by default \U causes a com-
@@ -1368,13 +1369,13 @@
pile time error (Perl uses \U to upper case subsequent characters).
(2) \u matches a lower case "u" character unless it is followed by four
- hexadecimal digits, in which case the hexadecimal number defines the
- code point to match. By default, \u causes a compile time error (Perl
+ hexadecimal digits, in which case the hexadecimal number defines the
+ code point to match. By default, \u causes a compile time error (Perl
uses it to upper case the following character).
- (3) \x matches a lower case "x" character unless it is followed by two
- hexadecimal digits, in which case the hexadecimal number defines the
- code point to match. By default, as in Perl, a hexadecimal number is
+ (3) \x matches a lower case "x" character unless it is followed by two
+ hexadecimal digits, in which case the hexadecimal number defines the
+ code point to match. By default, as in Perl, a hexadecimal number is
always expected after \x, but it may have zero, one, or two digits (so,
for example, \xz matches a binary zero character followed by z).
@@ -1381,62 +1382,62 @@
PCRE2_ALT_CIRCUMFLEX
In multiline mode (when PCRE2_MULTILINE is set), the circumflex
- metacharacter matches at the start of the subject (unless PCRE2_NOTBOL
- is set), and also after any internal newline. However, it does not
+ metacharacter matches at the start of the subject (unless PCRE2_NOTBOL
+ is set), and also after any internal newline. However, it does not
match after a newline at the end of the subject, for compatibility with
- Perl. If you want a multiline circumflex also to match after a termi-
+ Perl. If you want a multiline circumflex also to match after a termi-
nating newline, you must set PCRE2_ALT_CIRCUMFLEX.
PCRE2_ALT_VERBNAMES
- By default, for compatibility with Perl, the name in any verb sequence
- such as (*MARK:NAME) is any sequence of characters that does not
- include a closing parenthesis. The name is not processed in any way,
- and it is not possible to include a closing parenthesis in the name.
- However, if the PCRE2_ALT_VERBNAMES option is set, normal backslash
- processing is applied to verb names and only an unescaped closing
- parenthesis terminates the name. A closing parenthesis can be included
- in a name either as \) or between \Q and \E. If the PCRE2_EXTENDED or
- PCRE2_EXTENDED_MORE option is set, unescaped whitespace in verb names
- is skipped and #-comments are recognized in this mode, exactly as in
+ By default, for compatibility with Perl, the name in any verb sequence
+ such as (*MARK:NAME) is any sequence of characters that does not
+ include a closing parenthesis. The name is not processed in any way,
+ and it is not possible to include a closing parenthesis in the name.
+ However, if the PCRE2_ALT_VERBNAMES option is set, normal backslash
+ processing is applied to verb names and only an unescaped closing
+ parenthesis terminates the name. A closing parenthesis can be included
+ in a name either as \) or between \Q and \E. If the PCRE2_EXTENDED or
+ PCRE2_EXTENDED_MORE option is set, unescaped whitespace in verb names
+ is skipped and #-comments are recognized in this mode, exactly as in
the rest of the pattern.
PCRE2_AUTO_CALLOUT
- If this bit is set, pcre2_compile() automatically inserts callout
- items, all with number 255, before each pattern item, except immedi-
- ately before or after an explicit callout in the pattern. For discus-
+ If this bit is set, pcre2_compile() automatically inserts callout
+ items, all with number 255, before each pattern item, except immedi-
+ ately before or after an explicit callout in the pattern. For discus-
sion of the callout facility, see the pcre2callout documentation.
PCRE2_CASELESS
- If this bit is set, letters in the pattern match both upper and lower
- case letters in the subject. It is equivalent to Perl's /i option, and
- it can be changed within a pattern by a (?i) option setting. If
- PCRE2_UTF is set, Unicode properties are used for all characters with
- more than one other case, and for all characters whose code points are
- greater than U+007F. For lower valued characters with only one other
- case, a lookup table is used for speed. When PCRE2_UTF is not set, a
+ If this bit is set, letters in the pattern match both upper and lower
+ case letters in the subject. It is equivalent to Perl's /i option, and
+ it can be changed within a pattern by a (?i) option setting. If
+ PCRE2_UTF is set, Unicode properties are used for all characters with
+ more than one other case, and for all characters whose code points are
+ greater than U+007F. For lower valued characters with only one other
+ case, a lookup table is used for speed. When PCRE2_UTF is not set, a
lookup table is used for all code points less than 256, and higher code
- points (available only in 16-bit or 32-bit mode) are treated as not
+ points (available only in 16-bit or 32-bit mode) are treated as not
having another case.
PCRE2_DOLLAR_ENDONLY
- If this bit is set, a dollar metacharacter in the pattern matches only
- at the end of the subject string. Without this option, a dollar also
- matches immediately before a newline at the end of the string (but not
- before any other newlines). The PCRE2_DOLLAR_ENDONLY option is ignored
- if PCRE2_MULTILINE is set. There is no equivalent to this option in
+ If this bit is set, a dollar metacharacter in the pattern matches only
+ at the end of the subject string. Without this option, a dollar also
+ matches immediately before a newline at the end of the string (but not
+ before any other newlines). The PCRE2_DOLLAR_ENDONLY option is ignored
+ if PCRE2_MULTILINE is set. There is no equivalent to this option in
Perl, and no way to set it within a pattern.
PCRE2_DOTALL
- If this bit is set, a dot metacharacter in the pattern matches any
- character, including one that indicates a newline. However, it only
+ If this bit is set, a dot metacharacter in the pattern matches any
+ character, including one that indicates a newline. However, it only
ever matches one character, even if newlines are coded as CRLF. Without
this option, a dot does not match when the current position in the sub-
- ject is at a newline. This option is equivalent to Perl's /s option,
+ ject is at a newline. This option is equivalent to Perl's /s option,
and it can be changed within a pattern by a (?s) option setting. A neg-
ative class such as [^a] always matches newline characters, independent
of the setting of this option.
@@ -1443,271 +1444,271 @@
PCRE2_DUPNAMES
- If this bit is set, names used to identify capturing subpatterns need
+ If this bit is set, names used to identify capturing subpatterns need
not be unique. This can be helpful for certain types of pattern when it
- is known that only one instance of the named subpattern can ever be
- matched. There are more details of named subpatterns below; see also
+ is known that only one instance of the named subpattern can ever be
+ matched. There are more details of named subpatterns below; see also
the pcre2pattern documentation.
PCRE2_ENDANCHORED
- If this bit is set, the end of any pattern match must be right at the
+ If this bit is set, the end of any pattern match must be right at the
end of the string being searched (the "subject string"). If the pattern
match succeeds by reaching (*ACCEPT), but does not reach the end of the
- subject, the match fails at the current starting point. For unanchored
- patterns, a new match is then tried at the next starting point. How-
+ subject, the match fails at the current starting point. For unanchored
+ patterns, a new match is then tried at the next starting point. How-
ever, if the match succeeds by reaching the end of the pattern, but not
- the end of the subject, backtracking occurs and an alternative match
+ the end of the subject, backtracking occurs and an alternative match
may be found. Consider these two patterns:
.(*ACCEPT)|..
.|..
- If matched against "abc" with PCRE2_ENDANCHORED set, the first matches
- "c" whereas the second matches "bc". The effect of PCRE2_ENDANCHORED
- can also be achieved by appropriate constructs in the pattern itself,
+ If matched against "abc" with PCRE2_ENDANCHORED set, the first matches
+ "c" whereas the second matches "bc". The effect of PCRE2_ENDANCHORED
+ can also be achieved by appropriate constructs in the pattern itself,
which is the only way to do it in Perl.
For DFA matching with pcre2_dfa_match(), PCRE2_ENDANCHORED applies only
- to the first (that is, the longest) matched string. Other parallel
- matches, which are necessarily substrings of the first one, must obvi-
+ to the first (that is, the longest) matched string. Other parallel
+ matches, which are necessarily substrings of the first one, must obvi-
ously end before the end of the subject.
PCRE2_EXTENDED
- If this bit is set, most white space characters in the pattern are
- totally ignored except when escaped or inside a character class. How-
- ever, white space is not allowed within sequences such as (?> that
+ If this bit is set, most white space characters in the pattern are
+ totally ignored except when escaped or inside a character class. How-
+ ever, white space is not allowed within sequences such as (?> that
introduce various parenthesized subpatterns, nor within numerical quan-
- tifiers such as {1,3}. Ignorable white space is permitted between an
- item and a following quantifier and between a quantifier and a follow-
+ tifiers such as {1,3}. Ignorable white space is permitted between an
+ item and a following quantifier and between a quantifier and a follow-
ing + that indicates possessiveness.
- PCRE2_EXTENDED also causes characters between an unescaped # outside a
- character class and the next newline, inclusive, to be ignored, which
+ PCRE2_EXTENDED also causes characters between an unescaped # outside a
+ character class and the next newline, inclusive, to be ignored, which
makes it possible to include comments inside complicated patterns. Note
- that the end of this type of comment is a literal newline sequence in
+ that the end of this type of comment is a literal newline sequence in
the pattern; escape sequences that happen to represent a newline do not
- count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be
+ count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be
changed within a pattern by a (?x) option setting.
Which characters are interpreted as newlines can be specified by a set-
- ting in the compile context that is passed to pcre2_compile() or by a
- special sequence at the start of the pattern, as described in the sec-
- tion entitled "Newline conventions" in the pcre2pattern documentation.
+ ting in the compile context that is passed to pcre2_compile() or by a
+ special sequence at the start of the pattern, as described in the sec-
+ tion entitled "Newline conventions" in the pcre2pattern documentation.
A default is defined when PCRE2 is built.
PCRE2_EXTENDED_MORE
- This option has the effect of PCRE2_EXTENDED, but, in addition,
- unescaped space and horizontal tab characters are ignored inside a
- character class. PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx
- option, and it can be changed within a pattern by a (?xx) option set-
+ This option has the effect of PCRE2_EXTENDED, but, in addition,
+ unescaped space and horizontal tab characters are ignored inside a
+ character class. PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx
+ option, and it can be changed within a pattern by a (?xx) option set-
ting.
PCRE2_FIRSTLINE
If this option is set, the start of an unanchored pattern match must be
- before or at the first newline in the subject string following the
- start of matching, though the matched text may continue over the new-
+ before or at the first newline in the subject string following the
+ start of matching, though the matched text may continue over the new-
line. If startoffset is non-zero, the limiting newline is not necessar-
- ily the first newline in the subject. For example, if the subject
+ ily the first newline in the subject. For example, if the subject
string is "abc\nxyz" (where \n represents a single-character newline) a
- pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
- greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
- general limiting facility. If PCRE2_FIRSTLINE is set with an offset
- limit, a match must occur in the first line and also within the offset
+ pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
+ greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
+ general limiting facility. If PCRE2_FIRSTLINE is set with an offset
+ limit, a match must occur in the first line and also within the offset
limit. In other words, whichever limit comes first is used.
PCRE2_LITERAL
If this option is set, all meta-characters in the pattern are disabled,
- and it is treated as a literal string. Matching literal strings with a
+ and it is treated as a literal string. Matching literal strings with a
regular expression engine is not the most efficient way of doing it. If
- you are doing a lot of literal matching and are worried about effi-
+ you are doing a lot of literal matching and are worried about effi-
ciency, you should consider using other approaches. The only other main
options that are allowed with PCRE2_LITERAL are: PCRE2_ANCHORED,
PCRE2_ENDANCHORED, PCRE2_AUTO_CALLOUT, PCRE2_CASELESS, PCRE2_FIRSTLINE,
PCRE2_NO_START_OPTIMIZE, PCRE2_NO_UTF_CHECK, PCRE2_UTF, and
- PCRE2_USE_OFFSET_LIMIT. The extra options PCRE2_EXTRA_MATCH_LINE and
- PCRE2_EXTRA_MATCH_WORD are also supported. Any other options cause an
+ PCRE2_USE_OFFSET_LIMIT. The extra options PCRE2_EXTRA_MATCH_LINE and
+ PCRE2_EXTRA_MATCH_WORD are also supported. Any other options cause an
error.
PCRE2_MATCH_UNSET_BACKREF
- If this option is set, a backreference to an unset subpattern group
- matches an empty string (by default this causes the current matching
- alternative to fail). A pattern such as (\1)(a) succeeds when this
- option is set (assuming it can find an "a" in the subject), whereas it
- fails by default, for Perl compatibility. Setting this option makes
+ If this option is set, a backreference to an unset subpattern group
+ matches an empty string (by default this causes the current matching
+ alternative to fail). A pattern such as (\1)(a) succeeds when this
+ option is set (assuming it can find an "a" in the subject), whereas it
+ fails by default, for Perl compatibility. Setting this option makes
PCRE2 behave more like ECMAscript (aka JavaScript).
PCRE2_MULTILINE
- By default, for the purposes of matching "start of line" and "end of
- line", PCRE2 treats the subject string as consisting of a single line
- of characters, even if it actually contains newlines. The "start of
- line" metacharacter (^) matches only at the start of the string, and
- the "end of line" metacharacter ($) matches only at the end of the
+ By default, for the purposes of matching "start of line" and "end of
+ line", PCRE2 treats the subject string as consisting of a single line
+ of characters, even if it actually contains newlines. The "start of
+ line" metacharacter (^) matches only at the start of the string, and
+ the "end of line" metacharacter ($) matches only at the end of the
string, or before a terminating newline (except when PCRE2_DOL-
- LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set,
+ LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set,
the "any character" metacharacter (.) does not match at a newline. This
behaviour (for ^, $, and dot) is the same as Perl.
- When PCRE2_MULTILINE it is set, the "start of line" and "end of line"
- constructs match immediately following or immediately before internal
- newlines in the subject string, respectively, as well as at the very
- start and end. This is equivalent to Perl's /m option, and it can be
+ When PCRE2_MULTILINE it is set, the "start of line" and "end of line"
+ constructs match immediately following or immediately before internal
+ newlines in the subject string, respectively, as well as at the very
+ start and end. This is equivalent to Perl's /m option, and it can be
changed within a pattern by a (?m) option setting. Note that the "start
of line" metacharacter does not match after a newline at the end of the
- subject, for compatibility with Perl. However, you can change this by
- setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
- subject string, or no occurrences of ^ or $ in a pattern, setting
+ subject, for compatibility with Perl. However, you can change this by
+ setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
+ subject string, or no occurrences of ^ or $ in a pattern, setting
PCRE2_MULTILINE has no effect.
PCRE2_NEVER_BACKSLASH_C
- This option locks out the use of \C in the pattern that is being com-
- piled. This escape can cause unpredictable behaviour in UTF-8 or
- UTF-16 modes, because it may leave the current matching point in the
- middle of a multi-code-unit character. This option may be useful in
- applications that process patterns from external sources. Note that
+ This option locks out the use of \C in the pattern that is being com-
+ piled. This escape can cause unpredictable behaviour in UTF-8 or
+ UTF-16 modes, because it may leave the current matching point in the
+ middle of a multi-code-unit character. This option may be useful in
+ applications that process patterns from external sources. Note that
there is also a build-time option that permanently locks out the use of
\C.
PCRE2_NEVER_UCP
- This option locks out the use of Unicode properties for handling \B,
+ This option locks out the use of Unicode properties for handling \B,
\b, \D, \d, \S, \s, \W, \w, and some of the POSIX character classes, as
- described for the PCRE2_UCP option below. In particular, it prevents
- the creator of the pattern from enabling this facility by starting the
- pattern with (*UCP). This option may be useful in applications that
+ described for the PCRE2_UCP option below. In particular, it prevents
+ the creator of the pattern from enabling this facility by starting the
+ pattern with (*UCP). This option may be useful in applications that
process patterns from external sources. The option combination PCRE_UCP
and PCRE_NEVER_UCP causes an error.
PCRE2_NEVER_UTF
- This option locks out interpretation of the pattern as UTF-8, UTF-16,
+ This option locks out interpretation of the pattern as UTF-8, UTF-16,
or UTF-32, depending on which library is in use. In particular, it pre-
- vents the creator of the pattern from switching to UTF interpretation
- by starting the pattern with (*UTF). This option may be useful in
- applications that process patterns from external sources. The combina-
+ vents the creator of the pattern from switching to UTF interpretation
+ by starting the pattern with (*UTF). This option may be useful in
+ applications that process patterns from external sources. The combina-
tion of PCRE2_UTF and PCRE2_NEVER_UTF causes an error.
PCRE2_NO_AUTO_CAPTURE
If this option is set, it disables the use of numbered capturing paren-
- theses in the pattern. Any opening parenthesis that is not followed by
- ? behaves as if it were followed by ?: but named parentheses can still
+ theses in the pattern. Any opening parenthesis that is not followed by
+ ? behaves as if it were followed by ?: but named parentheses can still
be used for capturing (and they acquire numbers in the usual way). This
- is the same as Perl's /n option. Note that, when this option is set,
- references to capturing groups (backreferences or recursion/subroutine
- calls) may only refer to named groups, though the reference can be by
+ is the same as Perl's /n option. Note that, when this option is set,
+ references to capturing groups (backreferences or recursion/subroutine
+ calls) may only refer to named groups, though the reference can be by
name or by number.
PCRE2_NO_AUTO_POSSESS
If this option is set, it disables "auto-possessification", which is an
- optimization that, for example, turns a+b into a++b in order to avoid
- backtracks into a+ that can never be successful. However, if callouts
- are in use, auto-possessification means that some callouts are never
+ optimization that, for example, turns a+b into a++b in order to avoid
+ backtracks into a+ that can never be successful. However, if callouts
+ are in use, auto-possessification means that some callouts are never
taken. You can set this option if you want the matching functions to do
- a full unoptimized search and run all the callouts, but it is mainly
+ a full unoptimized search and run all the callouts, but it is mainly
provided for testing purposes.
PCRE2_NO_DOTSTAR_ANCHOR
If this option is set, it disables an optimization that is applied when
- .* is the first significant item in a top-level branch of a pattern,
- and all the other branches also start with .* or with \A or \G or ^.
- The optimization is automatically disabled for .* if it is inside an
- atomic group or a capturing group that is the subject of a backrefer-
- ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti-
- mization is not disabled, such a pattern is automatically anchored if
+ .* is the first significant item in a top-level branch of a pattern,
+ and all the other branches also start with .* or with \A or \G or ^.
+ The optimization is automatically disabled for .* if it is inside an
+ atomic group or a capturing group that is the subject of a backrefer-
+ ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti-
+ mization is not disabled, such a pattern is automatically anchored if
PCRE2_DOTALL is set for all the .* items and PCRE2_MULTILINE is not set
- for any ^ items. Otherwise, the fact that any match must start either
- at the start of the subject or following a newline is remembered. Like
+ for any ^ items. Otherwise, the fact that any match must start either
+ at the start of the subject or following a newline is remembered. Like
other optimizations, this can cause callouts to be skipped.
PCRE2_NO_START_OPTIMIZE
- This is an option whose main effect is at matching time. It does not
+ This is an option whose main effect is at matching time. It does not
change what pcre2_compile() generates, but it does affect the output of
the JIT compiler.
- There are a number of optimizations that may occur at the start of a
- match, in order to speed up the process. For example, if it is known
- that an unanchored match must start with a specific code unit value,
- the matching code searches the subject for that value, and fails imme-
- diately if it cannot find it, without actually running the main match-
- ing function. This means that a special item such as (*COMMIT) at the
- start of a pattern is not considered until after a suitable starting
- point for the match has been found. Also, when callouts or (*MARK)
- items are in use, these "start-up" optimizations can cause them to be
- skipped if the pattern is never actually used. The start-up optimiza-
- tions are in effect a pre-scan of the subject that takes place before
+ There are a number of optimizations that may occur at the start of a
+ match, in order to speed up the process. For example, if it is known
+ that an unanchored match must start with a specific code unit value,
+ the matching code searches the subject for that value, and fails imme-
+ diately if it cannot find it, without actually running the main match-
+ ing function. This means that a special item such as (*COMMIT) at the
+ start of a pattern is not considered until after a suitable starting
+ point for the match has been found. Also, when callouts or (*MARK)
+ items are in use, these "start-up" optimizations can cause them to be
+ skipped if the pattern is never actually used. The start-up optimiza-
+ tions are in effect a pre-scan of the subject that takes place before
the pattern is run.
The PCRE2_NO_START_OPTIMIZE option disables the start-up optimizations,
- possibly causing performance to suffer, but ensuring that in cases
- where the result is "no match", the callouts do occur, and that items
+ possibly causing performance to suffer, but ensuring that in cases
+ where the result is "no match", the callouts do occur, and that items
such as (*COMMIT) and (*MARK) are considered at every possible starting
position in the subject string.
- Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching
+ Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching
operation. Consider the pattern
(*COMMIT)ABC
- When this is compiled, PCRE2 records the fact that a match must start
- with the character "A". Suppose the subject string is "DEFABC". The
- start-up optimization scans along the subject, finds "A" and runs the
- first match attempt from there. The (*COMMIT) item means that the pat-
- tern must match the current starting position, which in this case, it
- does. However, if the same match is run with PCRE2_NO_START_OPTIMIZE
- set, the initial scan along the subject string does not happen. The
- first match attempt is run starting from "D" and when this fails,
- (*COMMIT) prevents any further matches being tried, so the overall
+ When this is compiled, PCRE2 records the fact that a match must start
+ with the character "A". Suppose the subject string is "DEFABC". The
+ start-up optimization scans along the subject, finds "A" and runs the
+ first match attempt from there. The (*COMMIT) item means that the pat-
+ tern must match the current starting position, which in this case, it
+ does. However, if the same match is run with PCRE2_NO_START_OPTIMIZE
+ set, the initial scan along the subject string does not happen. The
+ first match attempt is run starting from "D" and when this fails,
+ (*COMMIT) prevents any further matches being tried, so the overall
result is "no match".
- There are also other start-up optimizations. For example, a minimum
+ There are also other start-up optimizations. For example, a minimum
length for the subject may be recorded. Consider the pattern
(*MARK:A)(X|Y)
- The minimum length for a match is one character. If the subject is
+ The minimum length for a match is one character. If the subject is
"ABC", there will be attempts to match "ABC", "BC", and "C". An attempt
to match an empty string at the end of the subject does not take place,
- because PCRE2 knows that the subject is now too short, and so the
- (*MARK) is never encountered. In this case, the optimization does not
+ because PCRE2 knows that the subject is now too short, and so the
+ (*MARK) is never encountered. In this case, the optimization does not
affect the overall match result, which is still "no match", but it does
affect the auxiliary information that is returned.
PCRE2_NO_UTF_CHECK
- When PCRE2_UTF is set, the validity of the pattern as a UTF string is
- automatically checked. There are discussions about the validity of
- UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode
- document. If an invalid UTF sequence is found, pcre2_compile() returns
+ When PCRE2_UTF is set, the validity of the pattern as a UTF string is
+ automatically checked. There are discussions about the validity of
+ UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode
+ document. If an invalid UTF sequence is found, pcre2_compile() returns
a negative error code.
- If you know that your pattern is a valid UTF string, and you want to
- skip this check for performance reasons, you can set the
- PCRE2_NO_UTF_CHECK option. When it is set, the effect of passing an
+ If you know that your pattern is a valid UTF string, and you want to
+ skip this check for performance reasons, you can set the
+ PCRE2_NO_UTF_CHECK option. When it is set, the effect of passing an
invalid UTF string as a pattern is undefined. It may cause your program
to crash or loop.
Note that this option can also be passed to pcre2_match() and
- pcre_dfa_match(), to suppress UTF validity checking of the subject
+ pcre_dfa_match(), to suppress UTF validity checking of the subject
string.
Note also that setting PCRE2_NO_UTF_CHECK at compile time does not dis-
- able the error that is given if an escape sequence for an invalid Uni-
- code code point is encountered in the pattern. In particular, the so-
- called "surrogate" code points (0xd800 to 0xdfff) are invalid. If you
- want to allow escape sequences such as \x{d800} you can set the
- PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option, as described in the
- section entitled "Extra compile options" below. However, this is pos-
+ able the error that is given if an escape sequence for an invalid Uni-
+ code code point is encountered in the pattern. In particular, the so-
+ called "surrogate" code points (0xd800 to 0xdfff) are invalid. If you
+ want to allow escape sequences such as \x{d800} you can set the
+ PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option, as described in the
+ section entitled "Extra compile options" below. However, this is pos-
sible only in UTF-8 and UTF-32 modes, because these values are not rep-
resentable in UTF-16.
@@ -1714,106 +1715,106 @@
PCRE2_UCP
This option changes the way PCRE2 processes \B, \b, \D, \d, \S, \s, \W,
- \w, and some of the POSIX character classes. By default, only ASCII
- characters are recognized, but if PCRE2_UCP is set, Unicode properties
- are used instead to classify characters. More details are given in the
+ \w, and some of the POSIX character classes. By default, only ASCII
+ characters are recognized, but if PCRE2_UCP is set, Unicode properties
+ are used instead to classify characters. More details are given in the
section on generic character types in the pcre2pattern page. If you set
- PCRE2_UCP, matching one of the items it affects takes much longer. The
- option is available only if PCRE2 has been compiled with Unicode sup-
+ PCRE2_UCP, matching one of the items it affects takes much longer. The
+ option is available only if PCRE2 has been compiled with Unicode sup-
port (which is the default).
PCRE2_UNGREEDY
- This option inverts the "greediness" of the quantifiers so that they
- are not greedy by default, but become greedy if followed by "?". It is
- not compatible with Perl. It can also be set by a (?U) option setting
+ This option inverts the "greediness" of the quantifiers so that they
+ are not greedy by default, but become greedy if followed by "?". It is
+ not compatible with Perl. It can also be set by a (?U) option setting
within the pattern.
PCRE2_USE_OFFSET_LIMIT
This option must be set for pcre2_compile() if pcre2_set_offset_limit()
- is going to be used to set a non-default offset limit in a match con-
- text for matches that use this pattern. An error is generated if an
- offset limit is set without this option. For more details, see the
- description of pcre2_set_offset_limit() in the section that describes
+ is going to be used to set a non-default offset limit in a match con-
+ text for matches that use this pattern. An error is generated if an
+ offset limit is set without this option. For more details, see the
+ description of pcre2_set_offset_limit() in the section that describes
match contexts. See also the PCRE2_FIRSTLINE option above.
PCRE2_UTF
- This option causes PCRE2 to regard both the pattern and the subject
- strings that are subsequently processed as strings of UTF characters
- instead of single-code-unit strings. It is available when PCRE2 is
- built to include Unicode support (which is the default). If Unicode
- support is not available, the use of this option provokes an error.
- Details of how PCRE2_UTF changes the behaviour of PCRE2 are given in
+ This option causes PCRE2 to regard both the pattern and the subject
+ strings that are subsequently processed as strings of UTF characters
+ instead of single-code-unit strings. It is available when PCRE2 is
+ built to include Unicode support (which is the default). If Unicode
+ support is not available, the use of this option provokes an error.
+ Details of how PCRE2_UTF changes the behaviour of PCRE2 are given in
the pcre2unicode page.
Extra compile options
- Unlike the main compile-time options, the extra options are not saved
+ Unlike the main compile-time options, the extra options are not saved
with the compiled pattern. The option bits that can be set in a compile
- context by calling the pcre2_set_compile_extra_options() function are
+ context by calling the pcre2_set_compile_extra_options() function are
as follows:
PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
- This option applies when compiling a pattern in UTF-8 or UTF-32 mode.
- It is forbidden in UTF-16 mode, and ignored in non-UTF modes. Unicode
+ This option applies when compiling a pattern in UTF-8 or UTF-32 mode.
+ It is forbidden in UTF-16 mode, and ignored in non-UTF modes. Unicode
"surrogate" code points in the range 0xd800 to 0xdfff are used in pairs
- in UTF-16 to encode code points with values in the range 0x10000 to
- 0x10ffff. The surrogates cannot therefore be represented in UTF-16.
+ in UTF-16 to encode code points with values in the range 0x10000 to
+ 0x10ffff. The surrogates cannot therefore be represented in UTF-16.
They can be represented in UTF-8 and UTF-32, but are defined as invalid
- code points, and cause errors if encountered in a UTF-8 or UTF-32
+ code points, and cause errors if encountered in a UTF-8 or UTF-32
string that is being checked for validity by PCRE2.
- These values also cause errors if encountered in escape sequences such
+ These values also cause errors if encountered in escape sequences such
as \x{d912} within a pattern. However, it seems that some applications,
- when using PCRE2 to check for unwanted characters in UTF-8 strings,
- explicitly test for the surrogates using escape sequences. The
- PCRE2_NO_UTF_CHECK option does not disable the error that occurs,
- because it applies only to the testing of input strings for UTF valid-
+ when using PCRE2 to check for unwanted characters in UTF-8 strings,
+ explicitly test for the surrogates using escape sequences. The
+ PCRE2_NO_UTF_CHECK option does not disable the error that occurs,
+ because it applies only to the testing of input strings for UTF valid-
ity.
- If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
- gate code point values in UTF-8 and UTF-32 patterns no longer provoke
- errors and are incorporated in the compiled pattern. However, they can
- only match subject characters if the matching function is called with
+ If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
+ gate code point values in UTF-8 and UTF-32 patterns no longer provoke
+ errors and are incorporated in the compiled pattern. However, they can
+ only match subject characters if the matching function is called with
PCRE2_NO_UTF_CHECK set.
PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
- This is a dangerous option. Use with care. By default, an unrecognized
- escape such as \j or a malformed one such as \x{2z} causes a compile-
+ This is a dangerous option. Use with care. By default, an unrecognized
+ escape such as \j or a malformed one such as \x{2z} causes a compile-
time error when detected by pcre2_compile(). Perl is somewhat inconsis-
- tent in handling such items: for example, \j is treated as a literal
- "j", and non-hexadecimal digits in \x{} are just ignored, though warn-
- ings are given in both cases if Perl's warning switch is enabled. How-
- ever, a malformed octal number after \o{ always causes an error in
+ tent in handling such items: for example, \j is treated as a literal
+ "j", and non-hexadecimal digits in \x{} are just ignored, though warn-
+ ings are given in both cases if Perl's warning switch is enabled. How-
+ ever, a malformed octal number after \o{ always causes an error in
Perl.
- If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL extra option is passed to
- pcre2_compile(), all unrecognized or erroneous escape sequences are
- treated as single-character escapes. For example, \j is a literal "j"
- and \x{2z} is treated as the literal string "x{2z}". Setting this
- option means that typos in patterns may go undetected and have unex-
+ If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL extra option is passed to
+ pcre2_compile(), all unrecognized or erroneous escape sequences are
+ treated as single-character escapes. For example, \j is a literal "j"
+ and \x{2z} is treated as the literal string "x{2z}". Setting this
+ option means that typos in patterns may go undetected and have unex-
pected results. This is a dangerous option. Use with care.
PCRE2_EXTRA_MATCH_LINE
- This option is provided for use by the -x option of pcre2grep. It
- causes the pattern only to match complete lines. This is achieved by
- automatically inserting the code for "^(?:" at the start of the com-
- piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
- the matched line may be in the middle of the subject string. This
+ This option is provided for use by the -x option of pcre2grep. It
+ causes the pattern only to match complete lines. This is achieved by
+ automatically inserting the code for "^(?:" at the start of the com-
+ piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
+ the matched line may be in the middle of the subject string. This
option can be used with PCRE2_LITERAL.
PCRE2_EXTRA_MATCH_WORD
- This option is provided for use by the -w option of pcre2grep. It
- causes the pattern only to match strings that have a word boundary at
- the start and the end. This is achieved by automatically inserting the
- code for "\b(?:" at the start of the compiled pattern and ")\b" at the
- end. The option may be used with PCRE2_LITERAL. However, it is ignored
+ This option is provided for use by the -w option of pcre2grep. It
+ causes the pattern only to match strings that have a word boundary at
+ the start and the end. This is achieved by automatically inserting the
+ code for "\b(?:" at the start of the compiled pattern and ")\b" at the
+ end. The option may be used with PCRE2_LITERAL. However, it is ignored
if PCRE2_EXTRA_MATCH_LINE is also set.
@@ -1836,53 +1837,53 @@
void pcre2_jit_stack_free(pcre2_jit_stack *jit_stack);
- These functions provide support for JIT compilation, which, if the
- just-in-time compiler is available, further processes a compiled pat-
+ These functions provide support for JIT compilation, which, if the
+ just-in-time compiler is available, further processes a compiled pat-
tern into machine code that executes much faster than the pcre2_match()
- interpretive matching function. Full details are given in the pcre2jit
+ interpretive matching function. Full details are given in the pcre2jit
documentation.
- JIT compilation is a heavyweight optimization. It can take some time
- for patterns to be analyzed, and for one-off matches and simple pat-
- terns the benefit of faster execution might be offset by a much slower
- compilation time. Most (but not all) patterns can be optimized by the
+ JIT compilation is a heavyweight optimization. It can take some time
+ for patterns to be analyzed, and for one-off matches and simple pat-
+ terns the benefit of faster execution might be offset by a much slower
+ compilation time. Most (but not all) patterns can be optimized by the
JIT compiler.
LOCALE SUPPORT
- PCRE2 handles caseless matching, and determines whether characters are
- letters, digits, or whatever, by reference to a set of tables, indexed
- by character code point. This applies only to characters whose code
- points are less than 256. By default, higher-valued code points never
- match escapes such as \w or \d. However, if PCRE2 is built with Uni-
+ PCRE2 handles caseless matching, and determines whether characters are
+ letters, digits, or whatever, by reference to a set of tables, indexed
+ by character code point. This applies only to characters whose code
+ points are less than 256. By default, higher-valued code points never
+ match escapes such as \w or \d. However, if PCRE2 is built with Uni-
code support, all characters can be tested with \p and \P, or, alterna-
- tively, the PCRE2_UCP option can be set when a pattern is compiled;
- this causes \w and friends to use Unicode property support instead of
+ tively, the PCRE2_UCP option can be set when a pattern is compiled;
+ this causes \w and friends to use Unicode property support instead of
the built-in tables.
- The use of locales with Unicode is discouraged. If you are handling
- characters with code points greater than 128, you should either use
+ The use of locales with Unicode is discouraged. If you are handling
+ characters with code points greater than 128, you should either use
Unicode support, or use locales, but not try to mix the two.
- PCRE2 contains an internal set of character tables that are used by
- default. These are sufficient for many applications. Normally, the
+ PCRE2 contains an internal set of character tables that are used by
+ default. These are sufficient for many applications. Normally, the
internal tables recognize only ASCII characters. However, when PCRE2 is
built, it is possible to cause the internal tables to be rebuilt in the
default "C" locale of the local system, which may cause them to be dif-
ferent.
- The internal tables can be overridden by tables supplied by the appli-
- cation that calls PCRE2. These may be created in a different locale
- from the default. As more and more applications change to using Uni-
+ The internal tables can be overridden by tables supplied by the appli-
+ cation that calls PCRE2. These may be created in a different locale
+ from the default. As more and more applications change to using Uni-
code, the need for this locale support is expected to die away.
- External tables are built by calling the pcre2_maketables() function,
- in the relevant locale. The result can be passed to pcre2_compile() as
- often as necessary, by creating a compile context and calling
- pcre2_set_character_tables() to set the tables pointer therein. For
- example, to build and use tables that are appropriate for the French
- locale (where accented characters with values greater than 128 are
+ External tables are built by calling the pcre2_maketables() function,
+ in the relevant locale. The result can be passed to pcre2_compile() as
+ often as necessary, by creating a compile context and calling
+ pcre2_set_character_tables() to set the tables pointer therein. For
+ example, to build and use tables that are appropriate for the French
+ locale (where accented characters with values greater than 128 are
treated as letters), the following code could be used:
setlocale(LC_CTYPE, "fr_FR");
@@ -1891,15 +1892,15 @@
pcre2_set_character_tables(ccontext, tables);
re = pcre2_compile(..., ccontext);
- The locale name "fr_FR" is used on Linux and other Unix-like systems;
- if you are using Windows, the name for the French locale is "french".
- It is the caller's responsibility to ensure that the memory containing
+ The locale name "fr_FR" is used on Linux and other Unix-like systems;
+ if you are using Windows, the name for the French locale is "french".
+ It is the caller's responsibility to ensure that the memory containing
the tables remains available for as long as it is needed.
The pointer that is passed (via the compile context) to pcre2_compile()
- is saved with the compiled pattern, and the same tables are used by
- pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com-
- pilation and matching both happen in the same locale, but different
+ is saved with the compiled pattern, and the same tables are used by
+ pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com-
+ pilation and matching both happen in the same locale, but different
patterns can be processed in different locales.
@@ -1907,13 +1908,13 @@
int pcre2_pattern_info(const pcre2 *code, uint32_t what, void *where);
- The pcre2_pattern_info() function returns general information about a
+ The pcre2_pattern_info() function returns general information about a
compiled pattern. For information about callouts, see the next section.
- The first argument for pcre2_pattern_info() is a pointer to the com-
+ The first argument for pcre2_pattern_info() is a pointer to the com-
piled pattern. The second argument specifies which piece of information
- is required, and the third argument is a pointer to a variable to
- receive the data. If the third argument is NULL, the first argument is
- ignored, and the function returns the size in bytes of the variable
+ is required, and the third argument is a pointer to a variable to
+ receive the data. If the third argument is NULL, the first argument is
+ ignored, and the function returns the size in bytes of the variable
that is required for the information requested. Otherwise, the yield of
the function is zero for success, or one of the following negative num-
bers:
@@ -1923,9 +1924,9 @@
PCRE2_ERROR_BADOPTION the value of what was invalid
PCRE2_ERROR_UNSET the requested field is not set
- The "magic number" is placed at the start of each compiled pattern as
- an simple check against passing an arbitrary memory pointer. Here is a
- typical call of pcre2_pattern_info(), to obtain the length of the com-
+ The "magic number" is placed at the start of each compiled pattern as
+ an simple check against passing an arbitrary memory pointer. Here is a
+ typical call of pcre2_pattern_info(), to obtain the length of the com-
piled pattern:
int rc;
@@ -1943,22 +1944,22 @@
PCRE2_INFO_EXTRAOPTIONS
Return copies of the pattern's options. The third argument should point
- to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the
- options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
- TIONS returns the compile options as modified by any top-level (*XXX)
- option settings such as (*UTF) at the start of the pattern itself.
- PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in the
- compile context by calling the pcre2_set_compile_extra_options() func-
+ to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the
+ options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
+ TIONS returns the compile options as modified by any top-level (*XXX)
+ option settings such as (*UTF) at the start of the pattern itself.
+ PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in the
+ compile context by calling the pcre2_set_compile_extra_options() func-
tion.
- For example, if the pattern /(*UTF)abc/ is compiled with the
- PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is
- PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can
- change within a pattern do not affect the result of PCRE2_INFO_ALLOP-
+ For example, if the pattern /(*UTF)abc/ is compiled with the
+ PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is
+ PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can
+ change within a pattern do not affect the result of PCRE2_INFO_ALLOP-
TIONS, even if they appear right at the start of the pattern. (This was
different in some earlier releases.)
- A pattern compiled without PCRE2_ANCHORED is automatically anchored by
+ A pattern compiled without PCRE2_ANCHORED is automatically anchored by
PCRE2 if the first significant item in every top-level branch is one of
the following:
@@ -1967,7 +1968,7 @@
\G always
.* sometimes - see below
- When .* is the first significant item, anchoring is possible only when
+ When .* is the first significant item, anchoring is possible only when
all the following are true:
.* is not in an atomic group
@@ -1977,71 +1978,71 @@
Neither (*PRUNE) nor (*SKIP) appears in the pattern
PCRE2_NO_DOTSTAR_ANCHOR is not set
- For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in
+ For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in
the options returned for PCRE2_INFO_ALLOPTIONS.
PCRE2_INFO_BACKREFMAX
- Return the number of the highest backreference in the pattern. The
- third argument should point to an uint32_t variable. Named subpatterns
- acquire numbers as well as names, and these count towards the highest
- backreference. Backreferences such as \4 or \g{12} match the captured
- characters of the given group, but in addition, the check that a cap-
- turing group is set in a conditional subpattern such as (?(3)a|b) is
+ Return the number of the highest backreference in the pattern. The
+ third argument should point to an uint32_t variable. Named subpatterns
+ acquire numbers as well as names, and these count towards the highest
+ backreference. Backreferences such as \4 or \g{12} match the captured
+ characters of the given group, but in addition, the check that a cap-
+ turing group is set in a conditional subpattern such as (?(3)a|b) is
also a backreference. Zero is returned if there are no backreferences.
PCRE2_INFO_BSR
- The output is a uint32_t integer whose value indicates what character
- sequences the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
- means that \R matches any Unicode line ending sequence; a value of
+ The output is a uint32_t integer whose value indicates what character
+ sequences the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
+ means that \R matches any Unicode line ending sequence; a value of
PCRE2_BSR_ANYCRLF means that \R matches only CR, LF, or CRLF.
PCRE2_INFO_CAPTURECOUNT
- Return the highest capturing subpattern number in the pattern. In pat-
+ Return the highest capturing subpattern number in the pattern. In pat-
terns where (?| is not used, this is also the total number of capturing
subpatterns. The third argument should point to an uint32_t variable.
PCRE2_INFO_DEPTHLIMIT
- If the pattern set a backtracking depth limit by including an item of
- the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
+ If the pattern set a backtracking depth limit by including an item of
+ the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
third argument should point to a uint32_t integer. If no such value has
- been set, the call to pcre2_pattern_info() returns the error
+ been set, the call to pcre2_pattern_info() returns the error
PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
- ing if it is less than the limit set or defaulted by the caller of the
+ ing if it is less than the limit set or defaulted by the caller of the
match function.
PCRE2_INFO_FIRSTBITMAP
- In the absence of a single first code unit for a non-anchored pattern,
- pcre2_compile() may construct a 256-bit table that defines a fixed set
- of values for the first code unit in any match. For example, a pattern
- that starts with [abc] results in a table with three bits set. When
- code unit values greater than 255 are supported, the flag bit for 255
- means "any code unit of value 255 or above". If such a table was con-
- structed, a pointer to it is returned. Otherwise NULL is returned. The
+ In the absence of a single first code unit for a non-anchored pattern,
+ pcre2_compile() may construct a 256-bit table that defines a fixed set
+ of values for the first code unit in any match. For example, a pattern
+ that starts with [abc] results in a table with three bits set. When
+ code unit values greater than 255 are supported, the flag bit for 255
+ means "any code unit of value 255 or above". If such a table was con-
+ structed, a pointer to it is returned. Otherwise NULL is returned. The
third argument should point to a const uint8_t * variable.
PCRE2_INFO_FIRSTCODETYPE
Return information about the first code unit of any matched string, for
- a non-anchored pattern. The third argument should point to an uint32_t
- variable. If there is a fixed first value, for example, the letter "c"
- from a pattern such as (cat|cow|coyote), 1 is returned, and the value
- can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
- first value, but it is known that a match can occur only at the start
- of the subject or following a newline in the subject, 2 is returned.
+ a non-anchored pattern. The third argument should point to an uint32_t
+ variable. If there is a fixed first value, for example, the letter "c"
+ from a pattern such as (cat|cow|coyote), 1 is returned, and the value
+ can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
+ first value, but it is known that a match can occur only at the start
+ of the subject or following a newline in the subject, 2 is returned.
Otherwise, and for anchored patterns, 0 is returned.
PCRE2_INFO_FIRSTCODEUNIT
- Return the value of the first code unit of any matched string for a
- pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
- The third argument should point to an uint32_t variable. In the 8-bit
- library, the value is always less than 256. In the 16-bit library the
- value can be up to 0xffff. In the 32-bit library in UTF-32 mode the
+ Return the value of the first code unit of any matched string for a
+ pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
+ The third argument should point to an uint32_t variable. In the 8-bit
+ library, the value is always less than 256. In the 16-bit library the
+ value can be up to 0xffff. In the 32-bit library in UTF-32 mode the
value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32
mode.
@@ -2048,23 +2049,23 @@
PCRE2_INFO_FRAMESIZE
Return the size (in bytes) of the data frames that are used to remember
- backtracking positions when the pattern is processed by pcre2_match()
- without the use of JIT. The third argument should point to a size_t
+ backtracking positions when the pattern is processed by pcre2_match()
+ without the use of JIT. The third argument should point to a size_t
variable. The frame size depends on the number of capturing parentheses
- in the pattern. Each additional capturing group adds two PCRE2_SIZE
+ in the pattern. Each additional capturing group adds two PCRE2_SIZE
variables.
PCRE2_INFO_HASBACKSLASHC
- Return 1 if the pattern contains any instances of \C, otherwise 0. The
+ Return 1 if the pattern contains any instances of \C, otherwise 0. The
third argument should point to an uint32_t variable.
PCRE2_INFO_HASCRORLF
- Return 1 if the pattern contains any explicit matches for CR or LF
+ Return 1 if the pattern contains any explicit matches for CR or LF
characters, otherwise 0. The third argument should point to an uint32_t
- variable. An explicit match is either a literal CR or LF character, or
- \r or \n or one of the equivalent hexadecimal or octal escape
+ variable. An explicit match is either a literal CR or LF character, or
+ \r or \n or one of the equivalent hexadecimal or octal escape
sequences.
PCRE2_INFO_HEAPLIMIT
@@ -2072,81 +2073,81 @@
If the pattern set a heap memory limit by including an item of the form
(*LIMIT_HEAP=nnnn) at the start, the value is returned. The third argu-
ment should point to a uint32_t integer. If no such value has been set,
- the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
- Note that this limit will only be used during matching if it is less
+ the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
+ Note that this limit will only be used during matching if it is less
than the limit set or defaulted by the caller of the match function.
PCRE2_INFO_JCHANGED
- Return 1 if the (?J) or (?-J) option setting is used in the pattern,
- otherwise 0. The third argument should point to an uint32_t variable.
- (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
+ Return 1 if the (?J) or (?-J) option setting is used in the pattern,
+ otherwise 0. The third argument should point to an uint32_t variable.
+ (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
tively.
PCRE2_INFO_JITSIZE
- If the compiled pattern was successfully processed by pcre2_jit_com-
- pile(), return the size of the JIT compiled code, otherwise return
+ If the compiled pattern was successfully processed by pcre2_jit_com-
+ pile(), return the size of the JIT compiled code, otherwise return
zero. The third argument should point to a size_t variable.
PCRE2_INFO_LASTCODETYPE
- Returns 1 if there is a rightmost literal code unit that must exist in
- any matched string, other than at its start. The third argument should
- point to an uint32_t variable. If there is no such value, 0 is
- returned. When 1 is returned, the code unit value itself can be
- retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last
- literal value is recorded only if it follows something of variable
- length. For example, for the pattern /^a\d+z\d+/ the returned value is
- 1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/
+ Returns 1 if there is a rightmost literal code unit that must exist in
+ any matched string, other than at its start. The third argument should
+ point to an uint32_t variable. If there is no such value, 0 is
+ returned. When 1 is returned, the code unit value itself can be
+ retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last
+ literal value is recorded only if it follows something of variable
+ length. For example, for the pattern /^a\d+z\d+/ the returned value is
+ 1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/
the returned value is 0.
PCRE2_INFO_LASTCODEUNIT
- Return the value of the rightmost literal code unit that must exist in
- any matched string, other than at its start, for a pattern where
+ Return the value of the rightmost literal code unit that must exist in
+ any matched string, other than at its start, for a pattern where
PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argu-
ment should point to an uint32_t variable.
PCRE2_INFO_MATCHEMPTY
- Return 1 if the pattern might match an empty string, otherwise 0. The
- third argument should point to an uint32_t variable. When a pattern
+ Return 1 if the pattern might match an empty string, otherwise 0. The
+ third argument should point to an uint32_t variable. When a pattern
contains recursive subroutine calls it is not always possible to deter-
- mine whether or not it can match an empty string. PCRE2 takes a cau-
+ mine whether or not it can match an empty string. PCRE2 takes a cau-
tious approach and returns 1 in such cases.
PCRE2_INFO_MATCHLIMIT
- If the pattern set a match limit by including an item of the form
- (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third
- argument should point to a uint32_t integer. If no such value has been
- set, the call to pcre2_pattern_info() returns the error
+ If the pattern set a match limit by including an item of the form
+ (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third
+ argument should point to a uint32_t integer. If no such value has been
+ set, the call to pcre2_pattern_info() returns the error
PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
- ing if it is less than the limit set or defaulted by the caller of the
+ ing if it is less than the limit set or defaulted by the caller of the
match function.
PCRE2_INFO_MAXLOOKBEHIND
Return the number of characters (not code units) in the longest lookbe-
- hind assertion in the pattern. The third argument should point to a
- uint32_t integer. This information is useful when doing multi-segment
- matching using the partial matching facilities. Note that the simple
+ hind assertion in the pattern. The third argument should point to a
+ uint32_t integer. This information is useful when doing multi-segment
+ matching using the partial matching facilities. Note that the simple
assertions \b and \B require a one-character lookbehind. \A also regis-
- ters a one-character lookbehind, though it does not actually inspect
- the previous character. This is to ensure that at least one character
- from the old segment is retained when a new segment is processed. Oth-
- erwise, if there are no lookbehinds in the pattern, \A might match
+ ters a one-character lookbehind, though it does not actually inspect
+ the previous character. This is to ensure that at least one character
+ from the old segment is retained when a new segment is processed. Oth-
+ erwise, if there are no lookbehinds in the pattern, \A might match
incorrectly at the start of a second or subsequent segment.
PCRE2_INFO_MINLENGTH
- If a minimum length for matching subject strings was computed, its
- value is returned. Otherwise the returned value is 0. The value is a
- number of characters, which in UTF mode may be different from the num-
- ber of code units. The third argument should point to an uint32_t
- variable. The value is a lower bound to the length of any matching
- string. There may not be any strings of that length that do actually
+ If a minimum length for matching subject strings was computed, its
+ value is returned. Otherwise the returned value is 0. The value is a
+ number of characters, which in UTF mode may be different from the num-
+ ber of code units. The third argument should point to an uint32_t
+ variable. The value is a lower bound to the length of any matching
+ string. There may not be any strings of that length that do actually
match, but every string that does match is at least that long.
PCRE2_INFO_NAMECOUNT
@@ -2154,50 +2155,50 @@
PCRE2_INFO_NAMETABLE
PCRE2 supports the use of named as well as numbered capturing parenthe-
- ses. The names are just an additional way of identifying the parenthe-
+ ses. The names are just an additional way of identifying the parenthe-
ses, which still acquire numbers. Several convenience functions such as
- pcre2_substring_get_byname() are provided for extracting captured sub-
- strings by name. It is also possible to extract the data directly, by
- first converting the name to a number in order to access the correct
- pointers in the output vector (described with pcre2_match() below). To
- do the conversion, you need to use the name-to-number map, which is
+ pcre2_substring_get_byname() are provided for extracting captured sub-
+ strings by name. It is also possible to extract the data directly, by
+ first converting the name to a number in order to access the correct
+ pointers in the output vector (described with pcre2_match() below). To
+ do the conversion, you need to use the name-to-number map, which is
described by these three values.
- The map consists of a number of fixed-size entries. PCRE2_INFO_NAME-
- COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
- the size of each entry in code units; both of these return a uint32_t
+ The map consists of a number of fixed-size entries. PCRE2_INFO_NAME-
+ COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
+ the size of each entry in code units; both of these return a uint32_t
value. The entry size depends on the length of the longest name.
PCRE2_INFO_NAMETABLE returns a pointer to the first entry of the table.
- This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit
- library, the first two bytes of each entry are the number of the cap-
+ This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit
+ library, the first two bytes of each entry are the number of the cap-
turing parenthesis, most significant byte first. In the 16-bit library,
- the pointer points to 16-bit code units, the first of which contains
- the parenthesis number. In the 32-bit library, the pointer points to
- 32-bit code units, the first of which contains the parenthesis number.
+ the pointer points to 16-bit code units, the first of which contains
+ the parenthesis number. In the 32-bit library, the pointer points to
+ 32-bit code units, the first of which contains the parenthesis number.
The rest of the entry is the corresponding name, zero terminated.
- The names are in alphabetical order. If (?| is used to create multiple
- groups with the same number, as described in the section on duplicate
- subpattern numbers in the pcre2pattern page, the groups may be given
- the same name, but there is only one entry in the table. Different
+ The names are in alphabetical order. If (?| is used to create multiple
+ groups with the same number, as described in the section on duplicate
+ subpattern numbers in the pcre2pattern page, the groups may be given
+ the same name, but there is only one entry in the table. Different
names for groups of the same number are not permitted.
- Duplicate names for subpatterns with different numbers are permitted,
- but only if PCRE2_DUPNAMES is set. They appear in the table in the
- order in which they were found in the pattern. In the absence of (?|
- this is the order of increasing number; when (?| is used this is not
+ Duplicate names for subpatterns with different numbers are permitted,
+ but only if PCRE2_DUPNAMES is set. They appear in the table in the
+ order in which they were found in the pattern. In the absence of (?|
+ this is the order of increasing number; when (?| is used this is not
necessarily the case because later subpatterns may have lower numbers.
- As a simple example of the name/number table, consider the following
- pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED
+ As a simple example of the name/number table, consider the following
+ pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED
is set, so white space - including newlines - is ignored):
(?<date> (?<year>(\d\d)?\d\d) -
(?<month>\d\d) - (?<day>\d\d) )
- There are four named subpatterns, so the table has four entries, and
- each entry in the table is eight bytes long. The table is as follows,
+ There are four named subpatterns, so the table has four entries, and
+ each entry in the table is eight bytes long. The table is as follows,
with non-printing bytes shows in hexadecimal, and undefined bytes shown
as ??:
@@ -2206,8 +2207,8 @@
00 04 m o n t h 00
00 02 y e a r 00 ??
- When writing code to extract data from named subpatterns using the
- name-to-number map, remember that the length of the entries is likely
+ When writing code to extract data from named subpatterns using the
+ name-to-number map, remember that the length of the entries is likely
to be different for each compiled pattern.
PCRE2_INFO_NEWLINE
@@ -2226,14 +2227,14 @@
PCRE2_INFO_SIZE
- Return the size of the compiled pattern in bytes (for all three
- libraries). The third argument should point to a size_t variable. This
- value includes the size of the general data block that precedes the
- code units of the compiled pattern itself. The value that is used when
- pcre2_compile() is getting memory in which to place the compiled pat-
- tern may be slightly larger than the value returned by this option,
- because there are cases where the code that calculates the size has to
- over-estimate. Processing a pattern with the JIT compiler does not
+ Return the size of the compiled pattern in bytes (for all three
+ libraries). The third argument should point to a size_t variable. This
+ value includes the size of the general data block that precedes the
+ code units of the compiled pattern itself. The value that is used when
+ pcre2_compile() is getting memory in which to place the compiled pat-
+ tern may be slightly larger than the value returned by this option,
+ because there are cases where the code that calculates the size has to
+ over-estimate. Processing a pattern with the JIT compiler does not
alter the value returned by this option.
@@ -2244,22 +2245,22 @@
void *user_data);
A script language that supports the use of string arguments in callouts
- might like to scan all the callouts in a pattern before running the
+ might like to scan all the callouts in a pattern before running the
match. This can be done by calling pcre2_callout_enumerate(). The first
- argument is a pointer to a compiled pattern, the second points to a
- callback function, and the third is arbitrary user data. The callback
- function is called for every callout in the pattern in the order in
+ argument is a pointer to a compiled pattern, the second points to a
+ callback function, and the third is arbitrary user data. The callback
+ function is called for every callout in the pattern in the order in
which they appear. Its first argument is a pointer to a callout enumer-
- ation block, and its second argument is the user_data value that was
- passed to pcre2_callout_enumerate(). The contents of the callout enu-
- meration block are described in the pcre2callout documentation, which
+ ation block, and its second argument is the user_data value that was
+ passed to pcre2_callout_enumerate(). The contents of the callout enu-
+ meration block are described in the pcre2callout documentation, which
also gives further details about callouts.
SERIALIZATION AND PRECOMPILING
- It is possible to save compiled patterns on disc or elsewhere, and
- reload them later, subject to a number of restrictions. The functions
+ It is possible to save compiled patterns on disc or elsewhere, and
+ reload them later, subject to a number of restrictions. The functions
whose names begin with pcre2_serialize_ are used for this purpose. They
are described in the pcre2serialize documentation.
@@ -2274,56 +2275,56 @@
void pcre2_match_data_free(pcre2_match_data *match_data);
- Information about a successful or unsuccessful match is placed in a
- match data block, which is an opaque structure that is accessed by
- function calls. In particular, the match data block contains a vector
- of offsets into the subject string that define the matched part of the
- subject and any substrings that were captured. This is known as the
+ Information about a successful or unsuccessful match is placed in a
+ match data block, which is an opaque structure that is accessed by
+ function calls. In particular, the match data block contains a vector
+ of offsets into the subject string that define the matched part of the
+ subject and any substrings that were captured. This is known as the
ovector.
- Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
+ Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
you must create a match data block by calling one of the creation func-
- tions above. For pcre2_match_data_create(), the first argument is the
- number of pairs of offsets in the ovector. One pair of offsets is
+ tions above. For pcre2_match_data_create(), the first argument is the
+ number of pairs of offsets in the ovector. One pair of offsets is
required to identify the string that matched the whole pattern, with an
- additional pair for each captured substring. For example, a value of 4
- creates enough space to record the matched portion of the subject plus
- three captured substrings. A minimum of at least 1 pair is imposed by
+ additional pair for each captured substring. For example, a value of 4
+ creates enough space to record the matched portion of the subject plus
+ three captured substrings. A minimum of at least 1 pair is imposed by
pcre2_match_data_create(), so it is always possible to return the over-
all matched string.
The second argument of pcre2_match_data_create() is a pointer to a gen-
- eral context, which can specify custom memory management for obtaining
+ eral context, which can specify custom memory management for obtaining
the memory for the match data block. If you are not using custom memory
management, pass NULL, which causes malloc() to be used.
- For pcre2_match_data_create_from_pattern(), the first argument is a
+ For pcre2_match_data_create_from_pattern(), the first argument is a
pointer to a compiled pattern. The ovector is created to be exactly the
right size to hold all the substrings a pattern might capture. The sec-
- ond argument is again a pointer to a general context, but in this case
+ ond argument is again a pointer to a general context, but in this case
if NULL is passed, the memory is obtained using the same allocator that
was used for the compiled pattern (custom or default).
- A match data block can be used many times, with the same or different
- compiled patterns. You can extract information from a match data block
+ A match data block can be used many times, with the same or different
+ compiled patterns. You can extract information from a match data block
after a match operation has finished, using functions that are
- described in the sections on matched strings and other match data
+ described in the sections on matched strings and other match data
below.
- When a call of pcre2_match() fails, valid data is available in the
- match block only when the error is PCRE2_ERROR_NOMATCH,
- PCRE2_ERROR_PARTIAL, or one of the error codes for an invalid UTF
+ When a call of pcre2_match() fails, valid data is available in the
+ match block only when the error is PCRE2_ERROR_NOMATCH,
+ PCRE2_ERROR_PARTIAL, or one of the error codes for an invalid UTF
string. Exactly what is available depends on the error, and is detailed
below.
- When one of the matching functions is called, pointers to the compiled
- pattern and the subject string are set in the match data block so that
- they can be referenced by the extraction functions. After running a
- match, you must not free a compiled pattern or a subject string until
- after all operations on the match data block (for that match) have
+ When one of the matching functions is called, pointers to the compiled
+ pattern and the subject string are set in the match data block so that
+ they can be referenced by the extraction functions. After running a
+ match, you must not free a compiled pattern or a subject string until
+ after all operations on the match data block (for that match) have
taken place.
- When a match data block itself is no longer needed, it should be freed
+ When a match data block itself is no longer needed, it should be freed
by calling pcre2_match_data_free().
@@ -2334,15 +2335,15 @@
uint32_t options, pcre2_match_data *match_data,
pcre2_match_context *mcontext);
- The function pcre2_match() is called to match a subject string against
- a compiled pattern, which is passed in the code argument. You can call
+ The function pcre2_match() is called to match a subject string against
+ a compiled pattern, which is passed in the code argument. You can call
pcre2_match() with the same code argument as many times as you like, in
- order to find multiple matches in the subject string or to match dif-
+ order to find multiple matches in the subject string or to match dif-
ferent subject strings with the same pattern.
- This function is the main matching facility of the library, and it
- operates in a Perl-like manner. For specialist use there is also an
- alternative matching function, which is described below in the section
+ This function is the main matching facility of the library, and it
+ operates in a Perl-like manner. For specialist use there is also an
+ alternative matching function, which is described below in the section
about the pcre2_dfa_match() function.
Here is an example of a simple call to pcre2_match():
@@ -2357,7 +2358,7 @@
md, /* the match data block */
NULL); /* a match context; NULL means use defaults */
- If the subject string is zero-terminated, the length can be given as
+ If the subject string is zero-terminated, the length can be given as
PCRE2_ZERO_TERMINATED. A match context must be provided if certain less
common matching parameters are to be changed. For details, see the sec-
tion on the match context above.
@@ -2364,92 +2365,92 @@
The string to be matched by pcre2_match()
- The subject string is passed to pcre2_match() as a pointer in subject,
- a length in length, and a starting offset in startoffset. The length
- and offset are in code units, not characters. That is, they are in
- bytes for the 8-bit library, 16-bit code units for the 16-bit library,
- and 32-bit code units for the 32-bit library, whether or not UTF pro-
+ The subject string is passed to pcre2_match() as a pointer in subject,
+ a length in length, and a starting offset in startoffset. The length
+ and offset are in code units, not characters. That is, they are in
+ bytes for the 8-bit library, 16-bit code units for the 16-bit library,
+ and 32-bit code units for the 32-bit library, whether or not UTF pro-
cessing is enabled.
If startoffset is greater than the length of the subject, pcre2_match()
- returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the
- search for a match starts at the beginning of the subject, and this is
+ returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the
+ search for a match starts at the beginning of the subject, and this is
by far the most common case. In UTF-8 or UTF-16 mode, the starting off-
- set must point to the start of a character, or to the end of the sub-
- ject (in UTF-32 mode, one code unit equals one character, so all off-
- sets are valid). Like the pattern string, the subject may contain
+ set must point to the start of a character, or to the end of the sub-
+ ject (in UTF-32 mode, one code unit equals one character, so all off-
+ sets are valid). Like the pattern string, the subject may contain
binary zeros.
- A non-zero starting offset is useful when searching for another match
- in the same subject by calling pcre2_match() again after a previous
- success. Setting startoffset differs from passing over a shortened
- string and setting PCRE2_NOTBOL in the case of a pattern that begins
+ A non-zero starting offset is useful when searching for another match
+ in the same subject by calling pcre2_match() again after a previous
+ success. Setting startoffset differs from passing over a shortened
+ string and setting PCRE2_NOTBOL in the case of a pattern that begins
with any kind of lookbehind. For example, consider the pattern
\Biss\B
- which finds occurrences of "iss" in the middle of words. (\B matches
- only if the current position in the subject is not a word boundary.)
+ which finds occurrences of "iss" in the middle of words. (\B matches
+ only if the current position in the subject is not a word boundary.)
When applied to the string "Mississipi" the first call to pcre2_match()
- finds the first occurrence. If pcre2_match() is called again with just
- the remainder of the subject, namely "issipi", it does not match,
+ finds the first occurrence. If pcre2_match() is called again with just
+ the remainder of the subject, namely "issipi", it does not match,
because \B is always false at the start of the subject, which is deemed
- to be a word boundary. However, if pcre2_match() is passed the entire
+ to be a word boundary. However, if pcre2_match() is passed the entire
string again, but with startoffset set to 4, it finds the second occur-
- rence of "iss" because it is able to look behind the starting point to
+ rence of "iss" because it is able to look behind the starting point to
discover that it is preceded by a letter.
- Finding all the matches in a subject is tricky when the pattern can
+ Finding all the matches in a subject is tricky when the pattern can
match an empty string. It is possible to emulate Perl's /g behaviour by
- first trying the match again at the same offset, with the
- PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that
- fails, advancing the starting offset and trying an ordinary match
- again. There is some code that demonstrates how to do this in the
- pcre2demo sample program. In the most general case, you have to check
- to see if the newline convention recognizes CRLF as a newline, and if
- so, and the current character is CR followed by LF, advance the start-
+ first trying the match again at the same offset, with the
+ PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that
+ fails, advancing the starting offset and trying an ordinary match
+ again. There is some code that demonstrates how to do this in the
+ pcre2demo sample program. In the most general case, you have to check
+ to see if the newline convention recognizes CRLF as a newline, and if
+ so, and the current character is CR followed by LF, advance the start-
ing offset by two characters instead of one.
If a non-zero starting offset is passed when the pattern is anchored, a
single attempt to match at the given offset is made. This can only suc-
- ceed if the pattern does not require the match to be at the start of
- the subject. In other words, the anchoring must be the result of set-
- ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
+ ceed if the pattern does not require the match to be at the start of
+ the subject. In other words, the anchoring must be the result of set-
+ ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
by starting the pattern with ^ or \A.
Option bits for pcre2_match()
The unused bits of the options argument for pcre2_match() must be zero.
- The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDANCHORED,
- PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART,
- PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PAR-
+ The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDANCHORED,
+ PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART,
+ PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PAR-
TIAL_SOFT. Their action is described below.
- Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup-
- ported by the just-in-time (JIT) compiler. If it is set, JIT matching
- is disabled and the interpretive code in pcre2_match() is run. Apart
- from PCRE2_NO_JIT (obviously), the remaining options are supported for
+ Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup-
+ ported by the just-in-time (JIT) compiler. If it is set, JIT matching
+ is disabled and the interpretive code in pcre2_match() is run. Apart
+ from PCRE2_NO_JIT (obviously), the remaining options are supported for
JIT matching.
PCRE2_ANCHORED
The PCRE2_ANCHORED option limits pcre2_match() to matching at the first
- matching position. If a pattern was compiled with PCRE2_ANCHORED, or
- turned out to be anchored by virtue of its contents, it cannot be made
- unachored at matching time. Note that setting the option at match time
+ matching position. If a pattern was compiled with PCRE2_ANCHORED, or
+ turned out to be anchored by virtue of its contents, it cannot be made
+ unachored at matching time. Note that setting the option at match time
disables JIT matching.
PCRE2_ENDANCHORED
- If the PCRE2_ENDANCHORED option is set, any string that pcre2_match()
- matches must be right at the end of the subject string. Note that set-
+ If the PCRE2_ENDANCHORED option is set, any string that pcre2_match()
+ matches must be right at the end of the subject string. Note that set-
ting the option at match time disables JIT matching.
PCRE2_NOTBOL
This option specifies that first character of the subject string is not
- the beginning of a line, so the circumflex metacharacter should not
- match before it. Setting this without having set PCRE2_MULTILINE at
+ the beginning of a line, so the circumflex metacharacter should not
+ match before it. Setting this without having set PCRE2_MULTILINE at
compile time causes circumflex never to match. This option affects only
the behaviour of the circumflex metacharacter. It does not affect \A.
@@ -2456,9 +2457,9 @@
PCRE2_NOTEOL
This option specifies that the end of the subject string is not the end
- of a line, so the dollar metacharacter should not match it nor (except
- in multiline mode) a newline immediately before it. Setting this with-
- out having set PCRE2_MULTILINE at compile time causes dollar never to
+ of a line, so the dollar metacharacter should not match it nor (except
+ in multiline mode) a newline immediately before it. Setting this with-
+ out having set PCRE2_MULTILINE at compile time causes dollar never to
match. This option affects only the behaviour of the dollar metacharac-
ter. It does not affect \Z or \z.
@@ -2465,79 +2466,79 @@
PCRE2_NOTEMPTY
An empty string is not considered to be a valid match if this option is
- set. If there are alternatives in the pattern, they are tried. If all
- the alternatives match the empty string, the entire match fails. For
+ set. If there are alternatives in the pattern, they are tried. If all
+ the alternatives match the empty string, the entire match fails. For
example, if the pattern
a?b?
- is applied to a string not beginning with "a" or "b", it matches an
+ is applied to a string not beginning with "a" or "b", it matches an
empty string at the start of the subject. With PCRE2_NOTEMPTY set, this
- match is not valid, so pcre2_match() searches further into the string
+ match is not valid, so pcre2_match() searches further into the string
for occurrences of "a" or "b".
PCRE2_NOTEMPTY_ATSTART
- This is like PCRE2_NOTEMPTY, except that it locks out an empty string
+ This is like PCRE2_NOTEMPTY, except that it locks out an empty string
match only at the first matching position, that is, at the start of the
- subject plus the starting offset. An empty string match later in the
- subject is permitted. If the pattern is anchored, such a match can
+ subject plus the starting offset. An empty string match later in the
+ subject is permitted. If the pattern is anchored, such a match can
occur only if the pattern contains \K.
PCRE2_NO_JIT
- By default, if a pattern has been successfully processed by
- pcre2_jit_compile(), JIT is automatically used when pcre2_match() is
- called with options that JIT supports. Setting PCRE2_NO_JIT disables
+ By default, if a pattern has been successfully processed by
+ pcre2_jit_compile(), JIT is automatically used when pcre2_match() is
+ called with options that JIT supports. Setting PCRE2_NO_JIT disables
the use of JIT; it forces matching to be done by the interpreter.
PCRE2_NO_UTF_CHECK
When PCRE2_UTF is set at compile time, the validity of the subject as a
- UTF string is checked by default when pcre2_match() is subsequently
- called. If a non-zero starting offset is given, the check is applied
- only to that part of the subject that could be inspected during match-
- ing, and there is a check that the starting offset points to the first
- code unit of a character or to the end of the subject. If there are no
- lookbehind assertions in the pattern, the check starts at the starting
- offset. Otherwise, it starts at the length of the longest lookbehind
+ UTF string is checked by default when pcre2_match() is subsequently
+ called. If a non-zero starting offset is given, the check is applied
+ only to that part of the subject that could be inspected during match-
+ ing, and there is a check that the starting offset points to the first
+ code unit of a character or to the end of the subject. If there are no
+ lookbehind assertions in the pattern, the check starts at the starting
+ offset. Otherwise, it starts at the length of the longest lookbehind
before the starting offset, or at the start of the subject if there are
- not that many characters before the starting offset. Note that the
+ not that many characters before the starting offset. Note that the
sequences \b and \B are one-character lookbehinds.
The check is carried out before any other processing takes place, and a
- negative error code is returned if the check fails. There are several
- UTF error codes for each code unit width, corresponding to different
- problems with the code unit sequence. There are discussions about the
- validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the
+ negative error code is returned if the check fails. There are several
+ UTF error codes for each code unit width, corresponding to different
+ problems with the code unit sequence. There are discussions about the
+ validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the
pcre2unicode page.
- If you know that your subject is valid, and you want to skip these
- checks for performance reasons, you can set the PCRE2_NO_UTF_CHECK
- option when calling pcre2_match(). You might want to do this for the
+ If you know that your subject is valid, and you want to skip these
+ checks for performance reasons, you can set the PCRE2_NO_UTF_CHECK
+ option when calling pcre2_match(). You might want to do this for the
second and subsequent calls to pcre2_match() if you are making repeated
calls to find other matches in the same subject string.
- WARNING: When PCRE2_NO_UTF_CHECK is set, the effect of passing an
- invalid string as a subject, or an invalid value of startoffset, is
+ WARNING: When PCRE2_NO_UTF_CHECK is set, the effect of passing an
+ invalid string as a subject, or an invalid value of startoffset, is
undefined. Your program may crash or loop indefinitely.
PCRE2_PARTIAL_HARD
PCRE2_PARTIAL_SOFT
- These options turn on the partial matching feature. A partial match
- occurs if the end of the subject string is reached successfully, but
- there are not enough subject characters to complete the match. If this
- happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set,
- matching continues by testing any remaining alternatives. Only if no
- complete match can be found is PCRE2_ERROR_PARTIAL returned instead of
- PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that
- the caller is prepared to handle a partial match, but only if no com-
+ These options turn on the partial matching feature. A partial match
+ occurs if the end of the subject string is reached successfully, but
+ there are not enough subject characters to complete the match. If this
+ happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set,
+ matching continues by testing any remaining alternatives. Only if no
+ complete match can be found is PCRE2_ERROR_PARTIAL returned instead of
+ PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that
+ the caller is prepared to handle a partial match, but only if no com-
plete match can be found.
- If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
- case, if a partial match is found, pcre2_match() immediately returns
- PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
+ If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
+ case, if a partial match is found, pcre2_match() immediately returns
+ PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid-
ered to be more important that an alternative complete match.
@@ -2547,38 +2548,38 @@
NEWLINE HANDLING WHEN MATCHING
- When PCRE2 is built, a default newline convention is set; this is usu-
- ally the standard convention for the operating system. The default can
- be overridden in a compile context by calling pcre2_set_newline(). It
- can also be overridden by starting a pattern string with, for example,
- (*CRLF), as described in the section on newline conventions in the
- pcre2pattern page. During matching, the newline choice affects the be-
- haviour of the dot, circumflex, and dollar metacharacters. It may also
- alter the way the match starting position is advanced after a match
+ When PCRE2 is built, a default newline convention is set; this is usu-
+ ally the standard convention for the operating system. The default can
+ be overridden in a compile context by calling pcre2_set_newline(). It
+ can also be overridden by starting a pattern string with, for example,
+ (*CRLF), as described in the section on newline conventions in the
+ pcre2pattern page. During matching, the newline choice affects the be-
+ haviour of the dot, circumflex, and dollar metacharacters. It may also
+ alter the way the match starting position is advanced after a match
failure for an unanchored pattern.
When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is
- set as the newline convention, and a match attempt for an unanchored
+ set as the newline convention, and a match attempt for an unanchored
pattern fails when the current starting position is at a CRLF sequence,
- and the pattern contains no explicit matches for CR or LF characters,
- the match position is advanced by two characters instead of one, in
+ and the pattern contains no explicit matches for CR or LF characters,
+ the match position is advanced by two characters instead of one, in
other words, to after the CRLF.
The above rule is a compromise that makes the most common cases work as
- expected. For example, if the pattern is .+A (and the PCRE2_DOTALL
+ expected. For example, if the pattern is .+A (and the PCRE2_DOTALL
option is not set), it does not match the string "\r\nA" because, after
- failing at the start, it skips both the CR and the LF before retrying.
- However, the pattern [\r\n]A does match that string, because it con-
+ failing at the start, it skips both the CR and the LF before retrying.
+ However, the pattern [\r\n]A does match that string, because it con-
tains an explicit CR or LF reference, and so advances only by one char-
acter after the first failure.
An explicit match for CR of LF is either a literal appearance of one of
- those characters in the pattern, or one of the \r or \n or equivalent
+ those characters in the pattern, or one of the \r or \n or equivalent
octal or hexadecimal escape sequences. Implicit matches such as [^X] do
- not count, nor does \s, even though it includes CR and LF in the char-
+ not count, nor does \s, even though it includes CR and LF in the char-
acters that it matches.
- Notwithstanding the above, anomalous effects may still occur when CRLF
+ Notwithstanding the above, anomalous effects may still occur when CRLF
is a valid newline sequence and explicit \r or \n escapes appear in the
pattern.
@@ -2589,81 +2590,81 @@
PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data);
- In general, a pattern matches a certain portion of the subject, and in
- addition, further substrings from the subject may be picked out by
- parenthesized parts of the pattern. Following the usage in Jeffrey
- Friedl's book, this is called "capturing" in what follows, and the
- phrase "capturing subpattern" or "capturing group" is used for a frag-
- ment of a pattern that picks out a substring. PCRE2 supports several
+ In general, a pattern matches a certain portion of the subject, and in
+ addition, further substrings from the subject may be picked out by
+ parenthesized parts of the pattern. Following the usage in Jeffrey
+ Friedl's book, this is called "capturing" in what follows, and the
+ phrase "capturing subpattern" or "capturing group" is used for a frag-
+ ment of a pattern that picks out a substring. PCRE2 supports several
other kinds of parenthesized subpattern that do not cause substrings to
- be captured. The pcre2_pattern_info() function can be used to find out
+ be captured. The pcre2_pattern_info() function can be used to find out
how many capturing subpatterns there are in a compiled pattern.
- You can use auxiliary functions for accessing captured substrings by
+ You can use auxiliary functions for accessing captured substrings by
number or by name, as described in sections below.
Alternatively, you can make direct use of the vector of PCRE2_SIZE val-
- ues, called the ovector, which contains the offsets of captured
- strings. It is part of the match data block. The function
- pcre2_get_ovector_pointer() returns the address of the ovector, and
+ ues, called the ovector, which contains the offsets of captured
+ strings. It is part of the match data block. The function
+ pcre2_get_ovector_pointer() returns the address of the ovector, and
pcre2_get_ovector_count() returns the number of pairs of values it con-
tains.
Within the ovector, the first in each pair of values is set to the off-
set of the first code unit of a substring, and the second is set to the
- offset of the first code unit after the end of a substring. These val-
- ues are always code unit offsets, not character offsets. That is, they
- are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit
+ offset of the first code unit after the end of a substring. These val-
+ ues are always code unit offsets, not character offsets. That is, they
+ are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit
library, and 32-bit offsets in the 32-bit library.
- After a partial match (error return PCRE2_ERROR_PARTIAL), only the
- first pair of offsets (that is, ovector[0] and ovector[1]) are set.
- They identify the part of the subject that was partially matched. See
+ After a partial match (error return PCRE2_ERROR_PARTIAL), only the
+ first pair of offsets (that is, ovector[0] and ovector[1]) are set.
+ They identify the part of the subject that was partially matched. See
the pcre2partial documentation for details of partial matching.
- After a fully successful match, the first pair of offsets identifies
- the portion of the subject string that was matched by the entire pat-
- tern. The next pair is used for the first captured substring, and so
- on. The value returned by pcre2_match() is one more than the highest
- numbered pair that has been set. For example, if two substrings have
- been captured, the returned value is 3. If there are no captured sub-
+ After a fully successful match, the first pair of offsets identifies
+ the portion of the subject string that was matched by the entire pat-
+ tern. The next pair is used for the first captured substring, and so
+ on. The value returned by pcre2_match() is one more than the highest
+ numbered pair that has been set. For example, if two substrings have
+ been captured, the returned value is 3. If there are no captured sub-
strings, the return value from a successful match is 1, indicating that
just the first pair of offsets has been set.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
+ the match. For example, if the pattern (?=ab\K) is matched against
"ab", the start and end offset values for the match are 2 and 0.
- If a capturing subpattern group is matched repeatedly within a single
- match operation, it is the last portion of the subject that it matched
+ If a capturing subpattern group is matched repeatedly within a single
+ match operation, it is the last portion of the subject that it matched
that is returned.
If the ovector is too small to hold all the captured substring offsets,
- as much as possible is filled in, and the function returns a value of
- zero. If captured substrings are not of interest, pcre2_match() may be
+ as much as possible is filled in, and the function returns a value of
+ zero. If captured substrings are not of interest, pcre2_match() may be
called with a match data block whose ovector is of minimum length (that
is, one pair).
- It is possible for capturing subpattern number n+1 to match some part
+ It is possible for capturing subpattern number n+1 to match some part
of the subject when subpattern n has not been used at all. For example,
- if the string "abc" is matched against the pattern (a|(z))(bc) the
+ if the string "abc" is matched against the pattern (a|(z))(bc) the
return from the function is 4, and subpatterns 1 and 3 are matched, but
- 2 is not. When this happens, both values in the offset pairs corre-
+ 2 is not. When this happens, both values in the offset pairs corre-
sponding to unused subpatterns are set to PCRE2_UNSET.
- Offset values that correspond to unused subpatterns at the end of the
- expression are also set to PCRE2_UNSET. For example, if the string
+ Offset values that correspond to unused subpatterns at the end of the
+ expression are also set to PCRE2_UNSET. For example, if the string
"abc" is matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3
- are not matched. The return from the function is 2, because the high-
+ are not matched. The return from the function is 2, because the high-
est used capturing subpattern number is 1. The offsets for for the sec-
- ond and third capturing subpatterns (assuming the vector is large
+ ond and third capturing subpatterns (assuming the vector is large
enough, of course) are set to PCRE2_UNSET.
Elements in the ovector that do not correspond to capturing parentheses
in the pattern are never changed. That is, if a pattern contains n cap-
turing parentheses, no more than ovector[0] to ovector[2n+1] are set by
- pcre2_match(). The other elements retain whatever values they previ-
+ pcre2_match(). The other elements retain whatever values they previ-
ously had.
@@ -2673,46 +2674,46 @@
PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data);
- As well as the offsets in the ovector, other information about a match
- is retained in the match data block and can be retrieved by the above
- functions in appropriate circumstances. If they are called at other
+ As well as the offsets in the ovector, other information about a match
+ is retained in the match data block and can be retrieved by the above
+ functions in appropriate circumstances. If they are called at other
times, the result is undefined.
- After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
+ After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
failure to match (PCRE2_ERROR_NOMATCH), a (*MARK), (*PRUNE), or (*THEN)
- name may be available. The function pcre2_get_mark() can be called to
- access this name. The same function applies to all three verbs. It
+ name may be available. The function pcre2_get_mark() can be called to
+ access this name. The same function applies to all three verbs. It
returns a pointer to the zero-terminated name, which is within the com-
piled pattern. If no name is available, NULL is returned. The length of
- the name (excluding the terminating zero) is stored in the code unit
- that precedes the name. You should use this length instead of relying
+ the name (excluding the terminating zero) is stored in the code unit
+ that precedes the name. You should use this length instead of relying
on the terminating zero if the name might contain a binary zero.
- After a successful match, the name that is returned is the last
- (*MARK), (*PRUNE), or (*THEN) name encountered on the matching path
- through the pattern. Instances of (*PRUNE) and (*THEN) without names
- are ignored. Thus, for example, if the matching path contains
- (*MARK:A)(*PRUNE), the name "A" is returned. After a "no match" or a
- partial match, the last encountered name is returned. For example,
+ After a successful match, the name that is returned is the last
+ (*MARK), (*PRUNE), or (*THEN) name encountered on the matching path
+ through the pattern. Instances of (*PRUNE) and (*THEN) without names
+ are ignored. Thus, for example, if the matching path contains
+ (*MARK:A)(*PRUNE), the name "A" is returned. After a "no match" or a
+ partial match, the last encountered name is returned. For example,
consider this pattern:
^(*MARK:A)((*MARK:B)a|b)c
- When it matches "bc", the returned name is A. The B mark is "seen" in
- the first branch of the group, but it is not on the matching path. On
- the other hand, when this pattern fails to match "bx", the returned
+ When it matches "bc", the returned name is A. The B mark is "seen" in
+ the first branch of the group, but it is not on the matching path. On
+ the other hand, when this pattern fails to match "bx", the returned
name is B.
- After a successful match, a partial match, or one of the invalid UTF
- errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
+ After a successful match, a partial match, or one of the invalid UTF
+ errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
be called. After a successful or partial match it returns the code unit
- offset of the character at which the match started. For a non-partial
- match, this can be different to the value of ovector[0] if the pattern
- contains the \K escape sequence. After a partial match, however, this
- value is always the same as ovector[0] because \K does not affect the
+ offset of the character at which the match started. For a non-partial
+ match, this can be different to the value of ovector[0] if the pattern
+ contains the \K escape sequence. After a partial match, however, this
+ value is always the same as ovector[0] because \K does not affect the
result of a partial match.
- After a UTF check failure, pcre2_get_startchar() can be used to obtain
+ After a UTF check failure, pcre2_get_startchar() can be used to obtain
the code unit offset of the invalid UTF character. Details are given in
the pcre2unicode page.
@@ -2719,14 +2720,14 @@
ERROR RETURNS FROM pcre2_match()
- If pcre2_match() fails, it returns a negative number. This can be con-
- verted to a text string by calling the pcre2_get_error_message() func-
- tion (see "Obtaining a textual error message" below). Negative error
- codes are also returned by other functions, and are documented with
- them. The codes are given names in the header file. If UTF checking is
+ If pcre2_match() fails, it returns a negative number. This can be con-
+ verted to a text string by calling the pcre2_get_error_message() func-
+ tion (see "Obtaining a textual error message" below). Negative error
+ codes are also returned by other functions, and are documented with
+ them. The codes are given names in the header file. If UTF checking is
in force and an invalid UTF subject string is detected, one of a number
- of UTF-specific negative error codes is returned. Details are given in
- the pcre2unicode page. The following are the other errors that may be
+ of UTF-specific negative error codes is returned. Details are given in
+ the pcre2unicode page. The following are the other errors that may be
returned by pcre2_match():
PCRE2_ERROR_NOMATCH
@@ -2735,20 +2736,20 @@
PCRE2_ERROR_PARTIAL
- The subject string did not match, but it did match partially. See the
+ The subject string did not match, but it did match partially. See the
pcre2partial documentation for details of partial matching.
PCRE2_ERROR_BADMAGIC
PCRE2 stores a 4-byte "magic number" at the start of the compiled code,
- to catch the case when it is passed a junk pointer. This is the error
+ to catch the case when it is passed a junk pointer. This is the error
that is returned when the magic number is not present.
PCRE2_ERROR_BADMODE
- This error is given when a compiled pattern is passed to a function in
- a library of a different code unit width, for example, a pattern com-
- piled by the 8-bit library is passed to a 16-bit or 32-bit library
+ This error is given when a compiled pattern is passed to a function in
+ a library of a different code unit width, for example, a pattern com-
+ piled by the 8-bit library is passed to a 16-bit or 32-bit library
function.
PCRE2_ERROR_BADOFFSET
@@ -2762,15 +2763,15 @@
PCRE2_ERROR_BADUTFOFFSET
The UTF code unit sequence that was passed as a subject was checked and
- found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
- value of startoffset did not point to the beginning of a UTF character
+ found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
+ value of startoffset did not point to the beginning of a UTF character
or the end of the subject.
PCRE2_ERROR_CALLOUT
- This error is never generated by pcre2_match() itself. It is provided
- for use by callout functions that want to cause pcre2_match() or
- pcre2_callout_enumerate() to return a distinctive error code. See the
+ This error is never generated by pcre2_match() itself. It is provided
+ for use by callout functions that want to cause pcre2_match() or
+ pcre2_callout_enumerate() to return a distinctive error code. See the
pcre2callout documentation for details.
PCRE2_ERROR_DEPTHLIMIT
@@ -2783,14 +2784,14 @@
PCRE2_ERROR_INTERNAL
- An unexpected internal error has occurred. This error could be caused
+ An unexpected internal error has occurred. This error could be caused
by a bug in PCRE2 or by overwriting of the compiled pattern.
PCRE2_ERROR_JIT_STACKLIMIT
- This error is returned when a pattern that was successfully studied
- using JIT is being matched, but the memory available for the just-in-
- time processing stack is not large enough. See the pcre2jit documenta-
+ This error is returned when a pattern that was successfully studied
+ using JIT is being matched, but the memory available for the just-in-
+ time processing stack is not large enough. See the pcre2jit documenta-
tion for more details.
PCRE2_ERROR_MATCHLIMIT
@@ -2799,10 +2800,10 @@
PCRE2_ERROR_NOMEMORY
- If a pattern contains many nested backtracking points, heap memory is
- used to remember them. This error is given when the memory allocation
- function (default or custom) fails. Note that a different error,
- PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
+ If a pattern contains many nested backtracking points, heap memory is
+ used to remember them. This error is given when the memory allocation
+ function (default or custom) fails. Note that a different error,
+ PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
the heap limit.
PCRE2_ERROR_NULL
@@ -2811,12 +2812,12 @@
PCRE2_ERROR_RECURSELOOP
- This error is returned when pcre2_match() detects a recursion loop
- within the pattern. Specifically, it means that either the whole pat-
+ This error is returned when pcre2_match() detects a recursion loop
+ within the pattern. Specifically, it means that either the whole pat-
tern or a subpattern has been called recursively for the second time at
- the same position in the subject string. Some simple patterns that
- might do this are detected and faulted at compile time, but more com-
- plicated cases, in particular mutual recursions between two different
+ the same position in the subject string. Some simple patterns that
+ might do this are detected and faulted at compile time, but more com-
+ plicated cases, in particular mutual recursions between two different
subpatterns, cannot be detected until matching is attempted.
@@ -2825,20 +2826,20 @@
int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
PCRE2_SIZE bufflen);
- A text message for an error code from any PCRE2 function (compile,
- match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
- sage(). The code is passed as the first argument, with the remaining
- two arguments specifying a code unit buffer and its length in code
- units, into which the text message is placed. The message is returned
- in code units of the appropriate width for the library that is being
+ A text message for an error code from any PCRE2 function (compile,
+ match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
+ sage(). The code is passed as the first argument, with the remaining
+ two arguments specifying a code unit buffer and its length in code
+ units, into which the text message is placed. The message is returned
+ in code units of the appropriate width for the library that is being
used.
- The returned message is terminated with a trailing zero, and the func-
- tion returns the number of code units used, excluding the trailing
+ The returned message is terminated with a trailing zero, and the func-
+ tion returns the number of code units used, excluding the trailing
zero. If the error number is unknown, the negative error code
- PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes-
- sage is truncated (but still with a trailing zero), and the negative
- error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are
+ PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes-
+ sage is truncated (but still with a trailing zero), and the negative
+ error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are
very long; a buffer size of 120 code units is ample.
@@ -2857,39 +2858,39 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- Captured substrings can be accessed directly by using the ovector as
+ Captured substrings can be accessed directly by using the ovector as
described above. For convenience, auxiliary functions are provided for
- extracting captured substrings as new, separate, zero-terminated
+ extracting captured substrings as new, separate, zero-terminated
strings. A substring that contains a binary zero is correctly extracted
- and has a further zero added on the end, but the result is not, of
+ and has a further zero added on the end, but the result is not, of
course, a C string.
The functions in this section identify substrings by number. The number
zero refers to the entire matched substring, with higher numbers refer-
- ring to substrings captured by parenthesized groups. After a partial
- match, only substring zero is available. An attempt to extract any
- other substring gives the error PCRE2_ERROR_PARTIAL. The next section
+ ring to substrings captured by parenthesized groups. After a partial
+ match, only substring zero is available. An attempt to extract any
+ other substring gives the error PCRE2_ERROR_PARTIAL. The next section
describes similar functions for extracting captured substrings by name.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
- "ab", the start and end offset values for the match are 2 and 0. In
- this situation, calling these functions with a zero substring number
+ the match. For example, if the pattern (?=ab\K) is matched against
+ "ab", the start and end offset values for the match are 2 and 0. In
+ this situation, calling these functions with a zero substring number
extracts a zero-length empty string.
- You can find the length in code units of a captured substring without
- extracting it by calling pcre2_substring_length_bynumber(). The first
- argument is a pointer to the match data block, the second is the group
- number, and the third is a pointer to a variable into which the length
- is placed. If you just want to know whether or not the substring has
+ You can find the length in code units of a captured substring without
+ extracting it by calling pcre2_substring_length_bynumber(). The first
+ argument is a pointer to the match data block, the second is the group
+ number, and the third is a pointer to a variable into which the length
+ is placed. If you just want to know whether or not the substring has
been captured, you can pass the third argument as NULL.
- The pcre2_substring_copy_bynumber() function copies a captured sub-
- string into a supplied buffer, whereas pcre2_substring_get_bynumber()
- copies it into new memory, obtained using the same memory allocation
- function that was used for the match data block. The first two argu-
- ments of these functions are a pointer to the match data block and a
+ The pcre2_substring_copy_bynumber() function copies a captured sub-
+ string into a supplied buffer, whereas pcre2_substring_get_bynumber()
+ copies it into new memory, obtained using the same memory allocation
+ function that was used for the match data block. The first two argu-
+ ments of these functions are a pointer to the match data block and a
capturing group number.
The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -2898,25 +2899,25 @@
for the extracted substring, excluding the terminating zero.
For pcre2_substring_get_bynumber() the third and fourth arguments point
- to variables that are updated with a pointer to the new memory and the
- number of code units that comprise the substring, again excluding the
- terminating zero. When the substring is no longer needed, the memory
+ to variables that are updated with a pointer to the new memory and the
+ number of code units that comprise the substring, again excluding the
+ terminating zero. When the substring is no longer needed, the memory
should be freed by calling pcre2_substring_free().
- The return value from all these functions is zero for success, or a
- negative error code. If the pattern match failed, the match failure
- code is returned. If a substring number greater than zero is used
- after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
+ The return value from all these functions is zero for success, or a
+ negative error code. If the pattern match failed, the match failure
+ code is returned. If a substring number greater than zero is used
+ after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
error codes are:
PCRE2_ERROR_NOMEMORY
- The buffer was too small for pcre2_substring_copy_bynumber(), or the
+ The buffer was too small for pcre2_substring_copy_bynumber(), or the
attempt to get memory failed for pcre2_substring_get_bynumber().
PCRE2_ERROR_NOSUBSTRING
- There is no substring with that number in the pattern, that is, the
+ There is no substring with that number in the pattern, that is, the
number is greater than the number of capturing parentheses.
PCRE2_ERROR_UNAVAILABLE
@@ -2927,8 +2928,8 @@
PCRE2_ERROR_UNSET
- The substring did not participate in the match. For example, if the
- pattern is (abc)|(def) and the subject is "def", and the ovector con-
+ The substring did not participate in the match. For example, if the
+ pattern is (abc)|(def) and the subject is "def", and the ovector con-
tains at least two capturing slots, substring number 1 is unset.
@@ -2939,32 +2940,32 @@
void pcre2_substring_list_free(PCRE2_SPTR *list);
- The pcre2_substring_list_get() function extracts all available sub-
- strings and builds a list of pointers to them. It also (optionally)
- builds a second list that contains their lengths (in code units),
+ The pcre2_substring_list_get() function extracts all available sub-
+ strings and builds a list of pointers to them. It also (optionally)
+ builds a second list that contains their lengths (in code units),
excluding a terminating zero that is added to each of them. All this is
done in a single block of memory that is obtained using the same memory
allocation function that was used to get the match data block.
- This function must be called only after a successful match. If called
+ This function must be called only after a successful match. If called
after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.
- The address of the memory block is returned via listptr, which is also
+ The address of the memory block is returned via listptr, which is also
the start of the list of string pointers. The end of the list is marked
- by a NULL pointer. The address of the list of lengths is returned via
- lengthsptr. If your strings do not contain binary zeros and you do not
+ by a NULL pointer. The address of the list of lengths is returned via
+ lengthsptr. If your strings do not contain binary zeros and you do not
therefore need the lengths, you may supply NULL as the lengthsptr argu-
- ment to disable the creation of a list of lengths. The yield of the
- function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
- ory block could not be obtained. When the list is no longer needed, it
+ ment to disable the creation of a list of lengths. The yield of the
+ function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
+ ory block could not be obtained. When the list is no longer needed, it
should be freed by calling pcre2_substring_list_free().
If this function encounters a substring that is unset, which can happen
- when capturing subpattern number n+1 matches some part of the subject,
- but subpattern n has not been used at all, it returns an empty string.
- This can be distinguished from a genuine zero-length substring by
+ when capturing subpattern number n+1 matches some part of the subject,
+ but subpattern n has not been used at all, it returns an empty string.
+ This can be distinguished from a genuine zero-length substring by
inspecting the appropriate offset in the ovector, which contain
- PCRE2_UNSET for unset substrings, or by calling pcre2_sub-
+ PCRE2_UNSET for unset substrings, or by calling pcre2_sub-
string_length_bynumber().
@@ -2984,39 +2985,39 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- To extract a substring by name, you first have to find associated num-
+ To extract a substring by name, you first have to find associated num-
ber. For example, for this pattern:
(a+)b(?<xxx>\d+)...
the number of the subpattern called "xxx" is 2. If the name is known to
- be unique (PCRE2_DUPNAMES was not set), you can find the number from
+ be unique (PCRE2_DUPNAMES was not set), you can find the number from
the name by calling pcre2_substring_number_from_name(). The first argu-
- ment is the compiled pattern, and the second is the name. The yield of
+ ment is the compiled pattern, and the second is the name. The yield of
the function is the subpattern number, PCRE2_ERROR_NOSUBSTRING if there
- is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
- there is more than one subpattern of that name. Given the number, you
- can extract the substring directly from the ovector, or use one of the
+ is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
+ there is more than one subpattern of that name. Given the number, you
+ can extract the substring directly from the ovector, or use one of the
"bynumber" functions described above.
- For convenience, there are also "byname" functions that correspond to
- the "bynumber" functions, the only difference being that the second
- argument is a name instead of a number. If PCRE2_DUPNAMES is set and
+ For convenience, there are also "byname" functions that correspond to
+ the "bynumber" functions, the only difference being that the second
+ argument is a name instead of a number. If PCRE2_DUPNAMES is set and
there are duplicate names, these functions scan all the groups with the
given name, and return the first named string that is set.
- If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
- returned. If all groups with the name have numbers that are greater
- than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
- returned. If there is at least one group with a slot in the ovector,
+ If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
+ returned. If all groups with the name have numbers that are greater
+ than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
+ returned. If there is at least one group with a slot in the ovector,
but no group is found to be set, PCRE2_ERROR_UNSET is returned.
Warning: If the pattern uses the (?| feature to set up multiple subpat-
- terns with the same number, as described in the section on duplicate
- subpattern numbers in the pcre2pattern page, you cannot use names to
- distinguish the different subpatterns, because names are not included
- in the compiled code. The matching process uses only numbers. For this
- reason, the use of different names for subpatterns of the same number
+ terns with the same number, as described in the section on duplicate
+ subpattern numbers in the pcre2pattern page, you cannot use names to
+ distinguish the different subpatterns, because names are not included
+ in the compiled code. The matching process uses only numbers. For this
+ reason, the use of different names for subpatterns of the same number
causes an error at compile time.
@@ -3029,42 +3030,42 @@
PCRE2_SIZE rlength, PCRE2_UCHAR *outputbufferP,
PCRE2_SIZE *outlengthptr);
- This function calls pcre2_match() and then makes a copy of the subject
- string in outputbuffer, replacing the part that was matched with the
- replacement string, whose length is supplied in rlength. This can be
+ This function calls pcre2_match() and then makes a copy of the subject
+ string in outputbuffer, replacing the part that was matched with the
+ replacement string, whose length is supplied in rlength. This can be
given as PCRE2_ZERO_TERMINATED for a zero-terminated string. Matches in
- which a \K item in a lookahead in the pattern causes the match to end
+ which a \K item in a lookahead in the pattern causes the match to end
before it starts are not supported, and give rise to an error return.
- The first seven arguments of pcre2_substitute() are the same as for
+ The first seven arguments of pcre2_substitute() are the same as for
pcre2_match(), except that the partial matching options are not permit-
- ted, and match_data may be passed as NULL, in which case a match data
- block is obtained and freed within this function, using memory manage-
- ment functions from the match context, if provided, or else those that
+ ted, and match_data may be passed as NULL, in which case a match data
+ block is obtained and freed within this function, using memory manage-
+ ment functions from the match context, if provided, or else those that
were used to allocate memory for the compiled code.
- The outlengthptr argument must point to a variable that contains the
- length, in code units, of the output buffer. If the function is suc-
- cessful, the value is updated to contain the length of the new string,
+ The outlengthptr argument must point to a variable that contains the
+ length, in code units, of the output buffer. If the function is suc-
+ cessful, the value is updated to contain the length of the new string,
excluding the trailing zero that is automatically added.
- If the function is not successful, the value set via outlengthptr
- depends on the type of error. For syntax errors in the replacement
- string, the value is the offset in the replacement string where the
- error was detected. For other errors, the value is PCRE2_UNSET by
- default. This includes the case of the output buffer being too small,
- unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which
- case the value is the minimum length needed, including space for the
- trailing zero. Note that in order to compute the required length,
- pcre2_substitute() has to simulate all the matching and copying,
+ If the function is not successful, the value set via outlengthptr
+ depends on the type of error. For syntax errors in the replacement
+ string, the value is the offset in the replacement string where the
+ error was detected. For other errors, the value is PCRE2_UNSET by
+ default. This includes the case of the output buffer being too small,
+ unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which
+ case the value is the minimum length needed, including space for the
+ trailing zero. Note that in order to compute the required length,
+ pcre2_substitute() has to simulate all the matching and copying,
instead of giving an error return as soon as the buffer overflows. Note
also that the length is in code units, not bytes.
- In the replacement string, which is interpreted as a UTF string in UTF
- mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK
+ In the replacement string, which is interpreted as a UTF string in UTF
+ mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK
option is set, a dollar character is an escape character that can spec-
- ify the insertion of characters from capturing groups or (*MARK),
- (*PRUNE), or (*THEN) items in the pattern. The following forms are
+ ify the insertion of characters from capturing groups or (*MARK),
+ (*PRUNE), or (*THEN) items in the pattern. The following forms are
always recognized:
$$ insert a dollar character
@@ -3071,19 +3072,19 @@
$<n> or ${<n>} insert the contents of group <n>
$*MARK or ${*MARK} insert a (*MARK), (*PRUNE), or (*THEN) name
- Either a group number or a group name can be given for <n>. Curly
- brackets are required only if the following character would be inter-
+ Either a group number or a group name can be given for <n>. Curly
+ brackets are required only if the following character would be inter-
preted as part of the number or name. The number may be zero to include
- the entire matched string. For example, if the pattern a(b)c is
- matched with "=abc=" and the replacement string "+$1$0$1+", the result
+ the entire matched string. For example, if the pattern a(b)c is
+ matched with "=abc=" and the replacement string "+$1$0$1+", the result
is "=+babcb+=".
$*MARK inserts the name from the last encountered (*MARK), (*PRUNE), or
- (*THEN) on the matching path that has a name. (*MARK) must always
- include a name, but (*PRUNE) and (*THEN) need not. For example, in the
- case of (*MARK:A)(*PRUNE) the name inserted is "A", but for
- (*MARK:A)(*PRUNE:B) the relevant name is "B". This facility can be
- used to perform simple simultaneous substitutions, as this pcre2test
+ (*THEN) on the matching path that has a name. (*MARK) must always
+ include a name, but (*PRUNE) and (*THEN) need not. For example, in the
+ case of (*MARK:A)(*PRUNE) the name inserted is "A", but for
+ (*MARK:A)(*PRUNE:B) the relevant name is "B". This facility can be
+ used to perform simple simultaneous substitutions, as this pcre2test
example shows:
/(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
@@ -3090,19 +3091,19 @@
apple lemon
2: pear orange
- As well as the usual options for pcre2_match(), a number of additional
+ As well as the usual options for pcre2_match(), a number of additional
options can be set in the options argument of pcre2_substitute().
PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject
- string, replacing every matching substring. If this option is not set,
- only the first matching substring is replaced. The search for matches
- takes place in the original subject string (that is, previous replace-
- ments do not affect it). Iteration is implemented by advancing the
- startoffset value for each search, which is always passed the entire
+ string, replacing every matching substring. If this option is not set,
+ only the first matching substring is replaced. The search for matches
+ takes place in the original subject string (that is, previous replace-
+ ments do not affect it). Iteration is implemented by advancing the
+ startoffset value for each search, which is always passed the entire
subject string. If an offset limit is set in the match context, search-
ing stops when that limit is reached.
- You can restrict the effect of a global substitution to a portion of
+ You can restrict the effect of a global substitution to a portion of
the subject string by setting either or both of startoffset and an off-
set limit. Here is a pcre2test example:
@@ -3110,87 +3111,87 @@
ABC ABC ABC ABC\=offset=3,offset_limit=12
2: ABC A!C A!C ABC
- When continuing with global substitutions after matching a substring
+ When continuing with global substitutions after matching a substring
with zero length, an attempt to find a non-empty match at the same off-
set is performed. If this is not successful, the offset is advanced by
one character except when CRLF is a valid newline sequence and the next
- two characters are CR, LF. In this case, the offset is advanced by two
+ two characters are CR, LF. In this case, the offset is advanced by two
characters.
- PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
+ PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
- ORY immediately. If this option is set, however, pcre2_substitute()
+ ORY immediately. If this option is set, however, pcre2_substitute()
continues to go through the motions of matching and substituting (with-
- out, of course, writing anything) in order to compute the size of buf-
- fer that is needed. This value is passed back via the outlengthptr
- variable, with the result of the function still being
+ out, of course, writing anything) in order to compute the size of buf-
+ fer that is needed. This value is passed back via the outlengthptr
+ variable, with the result of the function still being
PCRE2_ERROR_NOMEMORY.
- Passing a buffer size of zero is a permitted way of finding out how
- much memory is needed for given substitution. However, this does mean
+ Passing a buffer size of zero is a permitted way of finding out how
+ much memory is needed for given substitution. However, this does mean
that the entire operation is carried out twice. Depending on the appli-
- cation, it may be more efficient to allocate a large buffer and free
- the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
+ cation, it may be more efficient to allocate a large buffer and free
+ the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
FLOW_LENGTH.
- PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups
- that do not appear in the pattern to be treated as unset groups. This
- option should be used with care, because it means that a typo in a
- group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING
+ PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups
+ that do not appear in the pattern to be treated as unset groups. This
+ option should be used with care, because it means that a typo in a
+ group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING
error.
- PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including
+ PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including
unknown groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be
- treated as empty strings when inserted as described above. If this
- option is not set, an attempt to insert an unset group causes the
- PCRE2_ERROR_UNSET error. This option does not influence the extended
+ treated as empty strings when inserted as described above. If this
+ option is not set, an attempt to insert an unset group causes the
+ PCRE2_ERROR_UNSET error. This option does not influence the extended
substitution syntax described below.
- PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
- replacement string. Without this option, only the dollar character is
- special, and only the group insertion forms listed above are valid.
+ PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
+ replacement string. Without this option, only the dollar character is
+ special, and only the group insertion forms listed above are valid.
When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:
- Firstly, backslash in a replacement string is interpreted as an escape
+ Firstly, backslash in a replacement string is interpreted as an escape
character. The usual forms such as \n or \x{ddd} can be used to specify
- particular character codes, and backslash followed by any non-alphanu-
- meric character quotes that character. Extended quoting can be coded
+ particular character codes, and backslash followed by any non-alphanu-
+ meric character quotes that character. Extended quoting can be coded
using \Q...\E, exactly as in pattern strings.
- There are also four escape sequences for forcing the case of inserted
- letters. The insertion mechanism has three states: no case forcing,
+ There are also four escape sequences for forcing the case of inserted
+ letters. The insertion mechanism has three states: no case forcing,
force upper case, and force lower case. The escape sequences change the
current state: \U and \L change to upper or lower case forcing, respec-
- tively, and \E (when not terminating a \Q quoted sequence) reverts to
- no case forcing. The sequences \u and \l force the next character (if
- it is a letter) to upper or lower case, respectively, and then the
+ tively, and \E (when not terminating a \Q quoted sequence) reverts to
+ no case forcing. The sequences \u and \l force the next character (if
+ it is a letter) to upper or lower case, respectively, and then the
state automatically reverts to no case forcing. Case forcing applies to
all inserted characters, including those from captured groups and let-
ters within \Q...\E quoted sequences.
Note that case forcing sequences such as \U...\E do not nest. For exam-
- ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
+ ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
\E has no effect.
- The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
- flexibility to group substitution. The syntax is similar to that used
+ The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
+ flexibility to group substitution. The syntax is similar to that used
by Bash:
${<n>:-<string>}
${<n>:+<string1>:<string2>}
- As before, <n> may be a group number or a name. The first form speci-
- fies a default value. If group <n> is set, its value is inserted; if
- not, <string> is expanded and the result inserted. The second form
- specifies strings that are expanded and inserted when group <n> is set
- or unset, respectively. The first form is just a convenient shorthand
+ As before, <n> may be a group number or a name. The first form speci-
+ fies a default value. If group <n> is set, its value is inserted; if
+ not, <string> is expanded and the result inserted. The second form
+ specifies strings that are expanded and inserted when group <n> is set
+ or unset, respectively. The first form is just a convenient shorthand
for
${<n>:+${<n>}:<string>}
- Backslash can be used to escape colons and closing curly brackets in
- the replacement strings. A change of the case forcing state within a
- replacement string remains in force afterwards, as shown in this
+ Backslash can be used to escape colons and closing curly brackets in
+ the replacement strings. A change of the case forcing state within a
+ replacement string remains in force afterwards, as shown in this
pcre2test example:
/(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@@ -3199,16 +3200,16 @@
somebody
1: HELLO
- The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
- substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause
+ The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
+ substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause
unknown groups in the extended syntax forms to be treated as unset.
- If successful, pcre2_substitute() returns the number of replacements
+ If successful, pcre2_substitute() returns the number of replacements
that were made. This may be zero if no matches were found, and is never
greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set.
In the event of an error, a negative error code is returned. Except for
- PCRE2_ERROR_NOMATCH (which is never returned), errors from
+ PCRE2_ERROR_NOMATCH (which is never returned), errors from
pcre2_match() are passed straight back.
PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser-
@@ -3215,25 +3216,25 @@
tion, unless PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set.
PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ-
- ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
+ ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
when the simple (non-extended) syntax is used and PCRE2_SUBSTI-
TUTE_UNSET_EMPTY is not set.
- PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
+ PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
- of buffer that is needed is returned via outlengthptr. Note that this
+ of buffer that is needed is returned via outlengthptr. Note that this
does not happen by default.
- PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
+ PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
the replacement string, with more particular errors being
- PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
- MISSINGBRACE (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
+ PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
+ MISSINGBRACE (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
TUTION (syntax error in extended group substitution), and
- PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before it started,
+ PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before it started,
which can happen if \K is used in an assertion).
As for all PCRE2 errors, a text message that describes the error can be
- obtained by calling the pcre2_get_error_message() function (see
+ obtained by calling the pcre2_get_error_message() function (see
"Obtaining a textual error message" above).
@@ -3242,56 +3243,56 @@
int pcre2_substring_nametable_scan(const pcre2_code *code,
PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last);
- When a pattern is compiled with the PCRE2_DUPNAMES option, names for
- subpatterns are not required to be unique. Duplicate names are always
- allowed for subpatterns with the same number, created by using the (?|
- feature. Indeed, if such subpatterns are named, they are required to
+ When a pattern is compiled with the PCRE2_DUPNAMES option, names for
+ subpatterns are not required to be unique. Duplicate names are always
+ allowed for subpatterns with the same number, created by using the (?|
+ feature. Indeed, if such subpatterns are named, they are required to
use the same names.
Normally, patterns with duplicate names are such that in any one match,
- only one of the named subpatterns participates. An example is shown in
+ only one of the named subpatterns participates. An example is shown in
the pcre2pattern documentation.
- When duplicates are present, pcre2_substring_copy_byname() and
- pcre2_substring_get_byname() return the first substring corresponding
- to the given name that is set. Only if none are set is
- PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name()
+ When duplicates are present, pcre2_substring_copy_byname() and
+ pcre2_substring_get_byname() return the first substring corresponding
+ to the given name that is set. Only if none are set is
+ PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name()
function returns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are
duplicate names.
- If you want to get full details of all captured substrings for a given
- name, you must use the pcre2_substring_nametable_scan() function. The
- first argument is the compiled pattern, and the second is the name. If
- the third and fourth arguments are NULL, the function returns a group
+ If you want to get full details of all captured substrings for a given
+ name, you must use the pcre2_substring_nametable_scan() function. The
+ first argument is the compiled pattern, and the second is the name. If
+ the third and fourth arguments are NULL, the function returns a group
number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise.
When the third and fourth arguments are not NULL, they must be pointers
- to variables that are updated by the function. After it has run, they
+ to variables that are updated by the function. After it has run, they
point to the first and last entries in the name-to-number table for the
- given name, and the function returns the length of each entry in code
- units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
+ given name, and the function returns the length of each entry in code
+ units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
no entries for the given name.
The format of the name table is described above in the section entitled
- Information about a pattern. Given all the relevant entries for the
- name, you can extract each of their numbers, and hence the captured
+ Information about a pattern. Given all the relevant entries for the
+ name, you can extract each of their numbers, and hence the captured
data.
FINDING ALL POSSIBLE MATCHES AT ONE POSITION
- The traditional matching function uses a similar algorithm to Perl,
- which stops when it finds the first match at a given point in the sub-
+ The traditional matching function uses a similar algorithm to Perl,
+ which stops when it finds the first match at a given point in the sub-
ject. If you want to find all possible matches, or the longest possible
- match at a given position, consider using the alternative matching
- function (see below) instead. If you cannot use the alternative func-
+ match at a given position, consider using the alternative matching
+ function (see below) instead. If you cannot use the alternative func-
tion, you can kludge it up by making use of the callout facility, which
is described in the pcre2callout documentation.
What you have to do is to insert a callout right at the end of the pat-
- tern. When your callout function is called, extract and save the cur-
- rent matched substring. Then return 1, which forces pcre2_match() to
- backtrack and try other alternatives. Ultimately, when it runs out of
+ tern. When your callout function is called, extract and save the cur-
+ rent matched substring. Then return 1, which forces pcre2_match() to
+ backtrack and try other alternatives. Ultimately, when it runs out of
matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH.
@@ -3303,26 +3304,26 @@
pcre2_match_context *mcontext,
int *workspace, PCRE2_SIZE wscount);
- The function pcre2_dfa_match() is called to match a subject string
- against a compiled pattern, using a matching algorithm that scans the
+ The function pcre2_dfa_match() is called to match a subject string
+ against a compiled pattern, using a matching algorithm that scans the
subject string just once (not counting lookaround assertions), and does
- not backtrack. This has different characteristics to the normal algo-
- rithm, and is not compatible with Perl. Some of the features of PCRE2
- patterns are not supported. Nevertheless, there are times when this
- kind of matching can be useful. For a discussion of the two matching
+ not backtrack. This has different characteristics to the normal algo-
+ rithm, and is not compatible with Perl. Some of the features of PCRE2
+ patterns are not supported. Nevertheless, there are times when this
+ kind of matching can be useful. For a discussion of the two matching
algorithms, and a list of features that pcre2_dfa_match() does not sup-
port, see the pcre2matching documentation.
- The arguments for the pcre2_dfa_match() function are the same as for
+ The arguments for the pcre2_dfa_match() function are the same as for
pcre2_match(), plus two extras. The ovector within the match data block
is used in a different way, and this is described below. The other com-
- mon arguments are used in the same way as for pcre2_match(), so their
+ mon arguments are used in the same way as for pcre2_match(), so their
description is not repeated here.
- The two additional arguments provide workspace for the function. The
- workspace vector should contain at least 20 elements. It is used for
+ The two additional arguments provide workspace for the function. The
+ workspace vector should contain at least 20 elements. It is used for
keeping track of multiple paths through the pattern tree. More
- workspace is needed for patterns and subjects where there are a lot of
+ workspace is needed for patterns and subjects where there are a lot of
potential matches.
Here is an example of a simple call to pcre2_dfa_match():
@@ -3342,45 +3343,45 @@
Option bits for pcre_dfa_match()
- The unused bits of the options argument for pcre2_dfa_match() must be
- zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDAN-
- CHORED, PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY,
+ The unused bits of the options argument for pcre2_dfa_match() must be
+ zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDAN-
+ CHORED, PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY,
PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD,
- PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but
- the last four of these are exactly the same as for pcre2_match(), so
+ PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but
+ the last four of these are exactly the same as for pcre2_match(), so
their description is not repeated here.
PCRE2_PARTIAL_HARD
PCRE2_PARTIAL_SOFT
- These have the same general effect as they do for pcre2_match(), but
- the details are slightly different. When PCRE2_PARTIAL_HARD is set for
- pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
+ These have the same general effect as they do for pcre2_match(), but
+ the details are slightly different. When PCRE2_PARTIAL_HARD is set for
+ pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
subject is reached and there is still at least one matching possibility
that requires additional characters. This happens even if some complete
- matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
- return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
- if the end of the subject is reached, there have been no complete
+ matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
+ return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
+ if the end of the subject is reached, there have been no complete
matches, but there is still at least one matching possibility. The por-
- tion of the string that was inspected when the longest partial match
+ tion of the string that was inspected when the longest partial match
was found is set as the first matching string in both cases. There is a
- more detailed discussion of partial and multi-segment matching, with
+ more detailed discussion of partial and multi-segment matching, with
examples, in the pcre2partial documentation.
PCRE2_DFA_SHORTEST
- Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
+ Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
stop as soon as it has found one match. Because of the way the alterna-
- tive algorithm works, this is necessarily the shortest possible match
+ tive algorithm works, this is necessarily the shortest possible match
at the first possible matching point in the subject string.
PCRE2_DFA_RESTART
- When pcre2_dfa_match() returns a partial match, it is possible to call
+ When pcre2_dfa_match() returns a partial match, it is possible to call
it again, with additional subject characters, and have it continue with
the same match. The PCRE2_DFA_RESTART option requests this action; when
- it is set, the workspace and wscount options must reference the same
- vector as before because data about the match so far is left in them
+ it is set, the workspace and wscount options must reference the same
+ vector as before because data about the match so far is left in them
after a partial match. There is more discussion of this facility in the
pcre2partial documentation.
@@ -3388,8 +3389,8 @@
When pcre2_dfa_match() succeeds, it may have matched more than one sub-
string in the subject. Note, however, that all the matches from one run
- of the function start at the same point in the subject. The shorter
- matches are all initial substrings of the longer matches. For example,
+ of the function start at the same point in the subject. The shorter
+ matches are all initial substrings of the longer matches. For example,
if the pattern
<.*>
@@ -3404,73 +3405,73 @@
<something> <something else>
<something>
- On success, the yield of the function is a number greater than zero,
- which is the number of matched substrings. The offsets of the sub-
- strings are returned in the ovector, and can be extracted by number in
- the same way as for pcre2_match(), but the numbers bear no relation to
- any capturing groups that may exist in the pattern, because DFA match-
+ On success, the yield of the function is a number greater than zero,
+ which is the number of matched substrings. The offsets of the sub-
+ strings are returned in the ovector, and can be extracted by number in
+ the same way as for pcre2_match(), but the numbers bear no relation to
+ any capturing groups that may exist in the pattern, because DFA match-
ing does not support group capture.
- Calls to the convenience functions that extract substrings by name
- return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used
+ Calls to the convenience functions that extract substrings by name
+ return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used
after a DFA match. The convenience functions that extract substrings by
number never return PCRE2_ERROR_NOSUBSTRING.
- The matched strings are stored in the ovector in reverse order of
- length; that is, the longest matching string is first. If there were
- too many matches to fit into the ovector, the yield of the function is
+ The matched strings are stored in the ovector in reverse order of
+ length; that is, the longest matching string is first. If there were
+ too many matches to fit into the ovector, the yield of the function is
zero, and the vector is filled with the longest matches.
- NOTE: PCRE2's "auto-possessification" optimization usually applies to
- character repeats at the end of a pattern (as well as internally). For
- example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
- matching, this means that only one possible match is found. If you
- really do want multiple matches in such cases, either use an ungreedy
- repeat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when
+ NOTE: PCRE2's "auto-possessification" optimization usually applies to
+ character repeats at the end of a pattern (as well as internally). For
+ example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
+ matching, this means that only one possible match is found. If you
+ really do want multiple matches in such cases, either use an ungreedy
+ repeat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when
compiling.
Error returns from pcre2_dfa_match()
The pcre2_dfa_match() function returns a negative number when it fails.
- Many of the errors are the same as for pcre2_match(), as described
+ Many of the errors are the same as for pcre2_match(), as described
above. There are in addition the following errors that are specific to
pcre2_dfa_match():
PCRE2_ERROR_DFA_UITEM
- This return is given if pcre2_dfa_match() encounters an item in the
- pattern that it does not support, for instance, the use of \C in a UTF
+ This return is given if pcre2_dfa_match() encounters an item in the
+ pattern that it does not support, for instance, the use of \C in a UTF
mode or a backreference.
PCRE2_ERROR_DFA_UCOND
- This return is given if pcre2_dfa_match() encounters a condition item
+ This return is given if pcre2_dfa_match() encounters a condition item
that uses a backreference for the condition, or a test for recursion in
a specific group. These are not supported.
PCRE2_ERROR_DFA_WSSIZE
- This return is given if pcre2_dfa_match() runs out of space in the
+ This return is given if pcre2_dfa_match() runs out of space in the
workspace vector.
PCRE2_ERROR_DFA_RECURSE
- When a recursive subpattern is processed, the matching function calls
+ When a recursive subpattern is processed, the matching function calls
itself recursively, using private memory for the ovector and workspace.
- This error is given if the internal ovector is not large enough. This
+ This error is given if the internal ovector is not large enough. This
should be extremely rare, as a vector of size 1000 is used.
PCRE2_ERROR_DFA_BADRESTART
- When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
- some plausibility checks are made on the contents of the workspace,
- which should contain data about the previous partial match. If any of
+ When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
+ some plausibility checks are made on the contents of the workspace,
+ which should contain data about the previous partial match. If any of
these checks fail, this error is given.
SEE ALSO
- pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
+ pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3).
@@ -3710,11 +3711,11 @@
part to another (for example, from an opening parenthesis to an alter-
nation metacharacter). By default, in the 8-bit and 16-bit libraries,
two-byte values are used for these offsets, leading to a maximum size
- for a compiled pattern of around 64K code units. This is sufficient to
- handle all but the most gigantic patterns. Nevertheless, some people do
- want to process truly enormous patterns, so it is possible to compile
- PCRE2 to use three-byte or four-byte offsets by adding a setting such
- as
+ for a compiled pattern of around 64 thousand code units. This is suffi-
+ cient to handle all but the most gigantic patterns. Nevertheless, some
+ people do want to process truly enormous patterns, so it is possible to
+ compile PCRE2 to use three-byte or four-byte offsets by adding a set-
+ ting such as
--with-link-size=3
@@ -3741,8 +3742,8 @@
pcre2_dfa_match() matching function, and to JIT matching (though the
counting is done differently).
- The pcre2_match() function starts out using a 20K vector on the system
- stack to record backtracking points. The more nested backtracking
+ The pcre2_match() function starts out using a 20KiB vector on the sys-
+ tem stack to record backtracking points. The more nested backtracking
points there are (that is, the deeper the search tree), the more memory
is needed. If the initial vector is not large enough, heap memory is
used, up to a certain limit, which is specified in kibibytes (units of
@@ -3857,14 +3858,14 @@
pcre2grep uses an internal buffer to hold a "window" on the file it is
scanning, in order to be able to output "before" and "after" lines when
- it finds a match. The starting size of the buffer is controlled by a
- parameter whose default value is 20K. The buffer itself is three times
- this size, but because of the way it is used for holding "before"
- lines, the longest line that is guaranteed to be processable is the
- parameter size. If a longer line is encountered, pcre2grep automati-
- cally expands the buffer, up to a specified maximum size, whose default
- is 1M or the starting size, whichever is the larger. You can change the
- default parameter values by adding, for example,
+ it finds a match. The default starting size of the buffer is 20KiB. The
+ buffer itself is three times this size, but because of the way it is
+ used for holding "before" lines, the longest line that is guaranteed to
+ be processable is the notional buffer size. If a longer line is encoun-
+ tered, pcre2grep automatically expands the buffer, up to a specified
+ maximum size, whose default is 1MiB or the starting size, whichever is
+ the larger. You can change the default parameter values by adding, for
+ example,
--with-pcre2grep-bufsize=51200
--with-pcre2grep-max-bufsize=2097152
@@ -4818,7 +4819,7 @@
CONTROLLING THE JIT STACK
When the compiled JIT code runs, it needs a block of memory to use as a
- stack. By default, it uses 32K on the machine stack. However, some
+ stack. By default, it uses 32KiB on the machine stack. However, some
large or complicated patterns need more than this. The error
PCRE2_ERROR_JIT_STACKLIMIT is given when there is not enough stack.
Three functions are provided for managing blocks of memory for use as
@@ -4832,9 +4833,10 @@
NULL if there is an error. The pcre2_jit_stack_free() function is used
to free a stack that is no longer needed. (For the technically minded:
the address space is allocated by mmap or VirtualAlloc.) A maximum
- stack size of 512K to 1M should be more than enough for any pattern.
+ stack size of 512KiB to 1MiB should be more than enough for any pat-
+ tern.
- The pcre2_jit_stack_assign() function specifies which stack JIT code
+ The pcre2_jit_stack_assign() function specifies which stack JIT code
should use. Its arguments are as follows:
pcre2_match_context *mcontext
@@ -4843,10 +4845,10 @@
The first argument is a pointer to a match context. When this is subse-
quently passed to a matching function, its information determines which
- JIT stack is used. There are three cases for the values of the other
+ JIT stack is used. There are three cases for the values of the other
two options:
- (1) If callback is NULL and data is NULL, an internal 32K block
+ (1) If callback is NULL and data is NULL, an internal 32KiB block
on the machine stack is used. This is the default when a match
context is created.
@@ -4857,38 +4859,38 @@
(3) If callback is not NULL, it must point to a function that is
called with data as an argument at the start of matching, in
order to set up a JIT stack. If the return from the callback
- function is NULL, the internal 32K stack is used; otherwise the
+ function is NULL, the internal 32KiB stack is used; otherwise the
return value must be a valid JIT stack, the result of calling
pcre2_jit_stack_create().
- A callback function is obeyed whenever JIT code is about to be run; it
+ A callback function is obeyed whenever JIT code is about to be run; it
is not obeyed when pcre2_match() is called with options that are incom-
- patible for JIT matching. A callback function can therefore be used to
- determine whether a match operation was executed by JIT or by the
+ patible for JIT matching. A callback function can therefore be used to
+ determine whether a match operation was executed by JIT or by the
interpreter.
You may safely use the same JIT stack for more than one pattern (either
- by assigning directly or by callback), as long as the patterns are
+ by assigning directly or by callback), as long as the patterns are
matched sequentially in the same thread. Currently, the only way to set
- up non-sequential matches in one thread is to use callouts: if a call-
- out function starts another match, that match must use a different JIT
+ up non-sequential matches in one thread is to use callouts: if a call-
+ out function starts another match, that match must use a different JIT
stack to the one used for currently suspended match(es).
- In a multithread application, if you do not specify a JIT stack, or if
- you assign or pass back NULL from a callback, that is thread-safe,
- because each thread has its own machine stack. However, if you assign
- or pass back a non-NULL JIT stack, this must be a different stack for
+ In a multithread application, if you do not specify a JIT stack, or if
+ you assign or pass back NULL from a callback, that is thread-safe,
+ because each thread has its own machine stack. However, if you assign
+ or pass back a non-NULL JIT stack, this must be a different stack for
each thread so that the application is thread-safe.
- Strictly speaking, even more is allowed. You can assign the same non-
- NULL stack to a match context that is used by any number of patterns,
- as long as they are not used for matching by multiple threads at the
- same time. For example, you could use the same stack in all compiled
- patterns, with a global mutex in the callback to wait until the stack
+ Strictly speaking, even more is allowed. You can assign the same non-
+ NULL stack to a match context that is used by any number of patterns,
+ as long as they are not used for matching by multiple threads at the
+ same time. For example, you could use the same stack in all compiled
+ patterns, with a global mutex in the callback to wait until the stack
is available for use. However, this is an inefficient solution, and not
recommended.
- This is a suggestion for how a multithreaded program that needs to set
+ This is a suggestion for how a multithreaded program that needs to set
up non-default JIT stacks might operate:
During thread initalization
@@ -4900,7 +4902,7 @@
Use a one-line callback function
return thread_local_var
- All the functions described in this section do nothing if JIT is not
+ All the functions described in this section do nothing if JIT is not
available.
@@ -4909,21 +4911,21 @@
(1) Why do we need JIT stacks?
PCRE2 (and JIT) is a recursive, depth-first engine, so it needs a stack
- where the local data of the current node is pushed before checking its
+ where the local data of the current node is pushed before checking its
child nodes. Allocating real machine stack on some platforms is diffi-
cult. For example, the stack chain needs to be updated every time if we
- extend the stack on PowerPC. Although it is possible, its updating
+ extend the stack on PowerPC. Although it is possible, its updating
time overhead decreases performance. So we do the recursion in memory.
(2) Why don't we simply allocate blocks of memory with malloc()?
- Modern operating systems have a nice feature: they can reserve an
+ Modern operating systems have a nice feature: they can reserve an
address space instead of allocating memory. We can safely allocate mem-
- ory pages inside this address space, so the stack could grow without
+ ory pages inside this address space, so the stack could grow without
moving memory data (this is important because of pointers). Thus we can
- allocate 1M address space, and use only a single memory page (usually
- 4K) if that is enough. However, we can still grow up to 1M anytime if
- needed.
+ allocate 1MiB address space, and use only a single memory page (usually
+ 4KiB) if that is enough. However, we can still grow up to 1MiB anytime
+ if needed.
(3) Who "owns" a JIT stack?
@@ -4930,8 +4932,8 @@
The owner of the stack is the user program, not the JIT studied pattern
or anything else. The user program must ensure that if a stack is being
used by pcre2_match(), (that is, it is assigned to a match context that
- is passed to the pattern currently running), that stack must not be
- used by any other threads (to avoid overwriting the same memory area).
+ is passed to the pattern currently running), that stack must not be
+ used by any other threads (to avoid overwriting the same memory area).
The best practice for multithreaded programs is to allocate a stack for
each thread, and return this stack through the JIT callback function.
@@ -4939,36 +4941,36 @@
You can free a JIT stack at any time, as long as it will not be used by
pcre2_match() again. When you assign the stack to a match context, only
- a pointer is set. There is no reference counting or any other magic.
+ a pointer is set. There is no reference counting or any other magic.
You can free compiled patterns, contexts, and stacks in any order, any-
- time. Just do not call pcre2_match() with a match context pointing to
+ time. Just do not call pcre2_match() with a match context pointing to
an already freed stack, as that will cause SEGFAULT. (Also, do not free
- a stack currently used by pcre2_match() in another thread). You can
- also replace the stack in a context at any time when it is not in use.
+ a stack currently used by pcre2_match() in another thread). You can
+ also replace the stack in a context at any time when it is not in use.
You should free the previous stack before assigning a replacement.
- (5) Should I allocate/free a stack every time before/after calling
+ (5) Should I allocate/free a stack every time before/after calling
pcre2_match()?
- No, because this is too costly in terms of resources. However, you
- could implement some clever idea which release the stack if it is not
- used in let's say two minutes. The JIT callback can help to achieve
+ No, because this is too costly in terms of resources. However, you
+ could implement some clever idea which release the stack if it is not
+ used in let's say two minutes. The JIT callback can help to achieve
this without keeping a list of patterns.
- (6) OK, the stack is for long term memory allocation. But what happens
- if a pattern causes stack overflow with a stack of 1M? Is that 1M kept
- until the stack is freed?
+ (6) OK, the stack is for long term memory allocation. But what happens
+ if a pattern causes stack overflow with a stack of 1MiB? Is that 1MiB
+ kept until the stack is freed?
- Especially on embedded sytems, it might be a good idea to release mem-
- ory sometimes without freeing the stack. There is no API for this at
- the moment. Probably a function call which returns with the currently
- allocated memory for any stack and another which allows releasing mem-
+ Especially on embedded sytems, it might be a good idea to release mem-
+ ory sometimes without freeing the stack. There is no API for this at
+ the moment. Probably a function call which returns with the currently
+ allocated memory for any stack and another which allows releasing mem-
ory (shrinking the stack) would be a good idea if someone needs this.
(7) This is too much of a headache. Isn't there any better solution for
JIT stack handling?
- No, thanks to Windows. If POSIX threads were used everywhere, we could
+ No, thanks to Windows. If POSIX threads were used everywhere, we could
throw out this complicated API.
@@ -4977,10 +4979,10 @@
void pcre2_jit_free_unused_memory(pcre2_general_context *gcontext);
The JIT executable allocator does not free all memory when it is possi-
- ble. It expects new allocations, and keeps some free memory around to
- improve allocation speed. However, in low memory conditions, it might
- be better to free all possible memory. You can cause this to happen by
- calling pcre2_jit_free_unused_memory(). Its argument is a general con-
+ ble. It expects new allocations, and keeps some free memory around to
+ improve allocation speed. However, in low memory conditions, it might
+ be better to free all possible memory. You can cause this to happen by
+ calling pcre2_jit_free_unused_memory(). Its argument is a general con-
text, for custom memory management, or NULL for standard memory manage-
ment.
@@ -4987,8 +4989,8 @@
EXAMPLE CODE
- This is a single-threaded example that specifies a JIT stack without
- using a callback. A real program should include error checking after
+ This is a single-threaded example that specifies a JIT stack without
+ using a callback. A real program should include error checking after
all the function calls.
int rc;
@@ -5016,29 +5018,29 @@
JIT FAST PATH API
Because the API described above falls back to interpreted matching when
- JIT is not available, it is convenient for programs that are written
+ JIT is not available, it is convenient for programs that are written
for general use in many environments. However, calling JIT via
pcre2_match() does have a performance impact. Programs that are written
- for use where JIT is known to be available, and which need the best
- possible performance, can instead use a "fast path" API to call JIT
- matching directly instead of calling pcre2_match() (obviously only for
+ for use where JIT is known to be available, and which need the best
+ possible performance, can instead use a "fast path" API to call JIT
+ matching directly instead of calling pcre2_match() (obviously only for
patterns that have been successfully processed by pcre2_jit_compile()).
- The fast path function is called pcre2_jit_match(), and it takes
+ The fast path function is called pcre2_jit_match(), and it takes
exactly the same arguments as pcre2_match(). The return values are also
the same, plus PCRE2_ERROR_JIT_BADOPTION if a matching mode (partial or
- complete) is requested that was not compiled. Unsupported option bits
- (for example, PCRE2_ANCHORED) are ignored, as is the PCRE2_NO_JIT
+ complete) is requested that was not compiled. Unsupported option bits
+ (for example, PCRE2_ANCHORED) are ignored, as is the PCRE2_NO_JIT
option.
- When you call pcre2_match(), as well as testing for invalid options, a
+ When you call pcre2_match(), as well as testing for invalid options, a
number of other sanity checks are performed on the arguments. For exam-
ple, if the subject pointer is NULL, an immediate error is given. Also,
- unless PCRE2_NO_UTF_CHECK is set, a UTF subject string is tested for
- validity. In the interests of speed, these checks do not happen on the
+ unless PCRE2_NO_UTF_CHECK is set, a UTF subject string is tested for
+ validity. In the interests of speed, these checks do not happen on the
JIT fast path, and if invalid data is passed, the result is undefined.
- Bypassing the sanity checks and the pcre2_match() wrapping can give
+ Bypassing the sanity checks and the pcre2_match() wrapping can give
speedups of more than 10%.
@@ -5073,16 +5075,16 @@
There are some size limitations in PCRE2 but it is hoped that they will
never in practice be relevant.
- The maximum size of a compiled pattern is approximately 64K code units
- for the 8-bit and 16-bit libraries if PCRE2 is compiled with the
- default internal linkage size, which is 2 bytes for these libraries. If
- you want to process regular expressions that are truly enormous, you
- can compile PCRE2 with an internal linkage size of 3 or 4 (when build-
- ing the 16-bit library, 3 is rounded up to 4). See the README file in
- the source distribution and the pcre2build documentation for details.
- In these cases the limit is substantially larger. However, the speed
- of execution is slower. In the 32-bit library, the internal linkage
- size is always 4.
+ The maximum size of a compiled pattern is approximately 64 thousand
+ code units for the 8-bit and 16-bit libraries if PCRE2 is compiled with
+ the default internal linkage size, which is 2 bytes for these
+ libraries. If you want to process regular expressions that are truly
+ enormous, you can compile PCRE2 with an internal linkage size of 3 or 4
+ (when building the 16-bit library, 3 is rounded up to 4). See the
+ README file in the source distribution and the pcre2build documentation
+ for details. In these cases the limit is substantially larger. How-
+ ever, the speed of execution is slower. In the 32-bit library, the
+ internal linkage size is always 4.
The maximum length of a source pattern string is essentially unlimited;
it is the largest number a PCRE2_SIZE variable can hold. However, the
@@ -6258,7 +6260,7 @@
The sequence \g followed by a signed or unsigned number, optionally
enclosed in braces, is an absolute or relative backreference. A named
- backreference can be coded as \g{name}. backreferences are discussed
+ backreference can be coded as \g{name}. Backreferences are discussed
later, following the discussion of parenthesized subpatterns.
Absolute and relative subroutine calls
@@ -7737,7 +7739,7 @@
the backreference. This can be done using alternation, as in the exam-
ple above, or by a quantifier with a minimum of zero.
- backreferences of this type cause the group that they reference to be
+ Backreferences of this type cause the group that they reference to be
treated as an atomic group. Once the whole group has been matched, a
subsequent matching failure cannot cause backtracking into the middle
of the group.
@@ -8937,28 +8939,27 @@
((ab){1,1000}c){1,3}
- uses over 50K bytes when compiled using the 8-bit library. When PCRE2
- is compiled with its default internal pointer size of two bytes, the
- size limit on a compiled pattern is 64K code units in the 8-bit and
- 16-bit libraries, and this is reached with the above pattern if the
- outer repetition is increased from 3 to 4. PCRE2 can be compiled to use
- larger internal pointers and thus handle larger compiled patterns, but
- it is better to try to rewrite your pattern to use less memory if you
- can.
+ uses over 50KiB when compiled using the 8-bit library. When PCRE2 is
+ compiled with its default internal pointer size of two bytes, the size
+ limit on a compiled pattern is 65535 code units in the 8-bit and 16-bit
+ libraries, and this is reached with the above pattern if the outer rep-
+ etition is increased from 3 to 4. PCRE2 can be compiled to use larger
+ internal pointers and thus handle larger compiled patterns, but it is
+ better to try to rewrite your pattern to use less memory if you can.
- One way of reducing the memory usage for such patterns is to make use
+ One way of reducing the memory usage for such patterns is to make use
of PCRE2's "subroutine" facility. Re-writing the above pattern as
((ab)(?2){0,999}c)(?1){0,2}
- reduces the memory requirements to around 16K, and indeed it remains
- under 20K even with the outer repetition increased to 100. However,
+ reduces the memory requirements to around 16KiB, and indeed it remains
+ under 20KiB even with the outer repetition increased to 100. However,
this kind of pattern is not always exactly equivalent, because any cap-
- tures within subroutine calls are lost when the subroutine completes.
- If this is not a problem, this kind of rewriting will allow you to
- process patterns that PCRE2 cannot otherwise handle. The matching per-
- formance of the two different versions of the pattern are roughly the
- same. (This applies from release 10.30 - things were different in ear-
+ tures within subroutine calls are lost when the subroutine completes.
+ If this is not a problem, this kind of rewriting will allow you to
+ process patterns that PCRE2 cannot otherwise handle. The matching per-
+ formance of the two different versions of the pattern are roughly the
+ same. (This applies from release 10.30 - things were different in ear-
lier releases.)
@@ -8965,96 +8966,96 @@
STACK AND HEAP USAGE AT RUN TIME
From release 10.30, the interpretive (non-JIT) version of pcre2_match()
- uses very little system stack at run time. In earlier releases recur-
- sive function calls could use a great deal of stack, and this could
- cause problems, but this usage has been eliminated. Backtracking posi-
- tions are now explicitly remembered in memory frames controlled by the
- code. An initial 20K vector of frames is allocated on the system stack
- (enough for about 100 frames for small patterns), but if this is insuf-
- ficient, heap memory is used. The amount of heap memory can be limited;
- if the limit is set to zero, only the initial stack vector is used.
- Rewriting patterns to be time-efficient, as described below, may also
- reduce the memory requirements.
+ uses very little system stack at run time. In earlier releases recur-
+ sive function calls could use a great deal of stack, and this could
+ cause problems, but this usage has been eliminated. Backtracking posi-
+ tions are now explicitly remembered in memory frames controlled by the
+ code. An initial 20KiB vector of frames is allocated on the system
+ stack (enough for about 100 frames for small patterns), but if this is
+ insufficient, heap memory is used. The amount of heap memory can be
+ limited; if the limit is set to zero, only the initial stack vector is
+ used. Rewriting patterns to be time-efficient, as described below, may
+ also reduce the memory requirements.
- In contrast to pcre2_match(), pcre2_dfa_match() does use recursive
- function calls, but only for processing atomic groups, lookaround
- assertions, and recursion within the pattern. The original version of
+ In contrast to pcre2_match(), pcre2_dfa_match() does use recursive
+ function calls, but only for processing atomic groups, lookaround
+ assertions, and recursion within the pattern. The original version of
the code used to allocate quite large internal workspace vectors on the
- stack, which caused some problems for some patterns in environments
- with small stacks. From release 10.32 the code for pcre2_dfa_match()
- has been re-factored to use heap memory when necessary for internal
- workspace when recursing, though recursive function calls are still
+ stack, which caused some problems for some patterns in environments
+ with small stacks. From release 10.32 the code for pcre2_dfa_match()
+ has been re-factored to use heap memory when necessary for internal
+ workspace when recursing, though recursive function calls are still
used.
- The "match depth" parameter can be used to limit the depth of function
- recursion, and the "match heap" parameter to limit heap memory in
+ The "match depth" parameter can be used to limit the depth of function
+ recursion, and the "match heap" parameter to limit heap memory in
pcre2_dfa_match().
PROCESSING TIME
- Certain items in regular expression patterns are processed more effi-
+ Certain items in regular expression patterns are processed more effi-
ciently than others. It is more efficient to use a character class like
- [aeiou] than a set of single-character alternatives such as
- (a|e|i|o|u). In general, the simplest construction that provides the
+ [aeiou] than a set of single-character alternatives such as
+ (a|e|i|o|u). In general, the simplest construction that provides the
required behaviour is usually the most efficient. Jeffrey Friedl's book
- contains a lot of useful general discussion about optimizing regular
- expressions for efficient performance. This document contains a few
+ contains a lot of useful general discussion about optimizing regular
+ expressions for efficient performance. This document contains a few
observations about PCRE2.
- Using Unicode character properties (the \p, \P, and \X escapes) is
- slow, because PCRE2 has to use a multi-stage table lookup whenever it
- needs a character's property. If you can find an alternative pattern
+ Using Unicode character properties (the \p, \P, and \X escapes) is
+ slow, because PCRE2 has to use a multi-stage table lookup whenever it
+ needs a character's property. If you can find an alternative pattern
that does not use character properties, it will probably be faster.
- By default, the escape sequences \b, \d, \s, and \w, and the POSIX
- character classes such as [:alpha:] do not use Unicode properties,
+ By default, the escape sequences \b, \d, \s, and \w, and the POSIX
+ character classes such as [:alpha:] do not use Unicode properties,
partly for backwards compatibility, and partly for performance reasons.
- However, you can set the PCRE2_UCP option or start the pattern with
- (*UCP) if you want Unicode character properties to be used. This can
- double the matching time for items such as \d, when matched with
- pcre2_match(); the performance loss is less with a DFA matching func-
+ However, you can set the PCRE2_UCP option or start the pattern with
+ (*UCP) if you want Unicode character properties to be used. This can
+ double the matching time for items such as \d, when matched with
+ pcre2_match(); the performance loss is less with a DFA matching func-
tion, and in both cases there is not much difference for \b.
- When a pattern begins with .* not in atomic parentheses, nor in paren-
- theses that are the subject of a backreference, and the PCRE2_DOTALL
- option is set, the pattern is implicitly anchored by PCRE2, since it
- can match only at the start of a subject string. If the pattern has
+ When a pattern begins with .* not in atomic parentheses, nor in paren-
+ theses that are the subject of a backreference, and the PCRE2_DOTALL
+ option is set, the pattern is implicitly anchored by PCRE2, since it
+ can match only at the start of a subject string. If the pattern has
multiple top-level branches, they must all be anchorable. The optimiza-
- tion can be disabled by the PCRE2_NO_DOTSTAR_ANCHOR option, and is
+ tion can be disabled by the PCRE2_NO_DOTSTAR_ANCHOR option, and is
automatically disabled if the pattern contains (*PRUNE) or (*SKIP).
- If PCRE2_DOTALL is not set, PCRE2 cannot make this optimization,
+ If PCRE2_DOTALL is not set, PCRE2 cannot make this optimization,
because the dot metacharacter does not then match a newline, and if the
- subject string contains newlines, the pattern may match from the char-
+ subject string contains newlines, the pattern may match from the char-
acter immediately following one of them instead of from the very start.
For example, the pattern
.*second
- matches the subject "first\nand second" (where \n stands for a newline
- character), with the match starting at the seventh character. In order
- to do this, PCRE2 has to retry the match starting after every newline
+ matches the subject "first\nand second" (where \n stands for a newline
+ character), with the match starting at the seventh character. In order
+ to do this, PCRE2 has to retry the match starting after every newline
in the subject.
- If you are using such a pattern with subject strings that do not con-
- tain newlines, the best performance is obtained by setting
- PCRE2_DOTALL, or starting the pattern with ^.* or ^.*? to indicate
+ If you are using such a pattern with subject strings that do not con-
+ tain newlines, the best performance is obtained by setting
+ PCRE2_DOTALL, or starting the pattern with ^.* or ^.*? to indicate
explicit anchoring. That saves PCRE2 from having to scan along the sub-
ject looking for a newline to restart at.
- Beware of patterns that contain nested indefinite repeats. These can
- take a long time to run when applied to a string that does not match.
+ Beware of patterns that contain nested indefinite repeats. These can
+ take a long time to run when applied to a string that does not match.
Consider the pattern fragment
^(a+)*
- This can match "aaaa" in 16 different ways, and this number increases
- very rapidly as the string gets longer. (The * repeat can match 0, 1,
- 2, 3, or 4 times, and for each of those cases other than 0 or 4, the +
- repeats can match different numbers of times.) When the remainder of
- the pattern is such that the entire match is going to fail, PCRE2 has
- in principle to try every possible variation, and this can take an
+ This can match "aaaa" in 16 different ways, and this number increases
+ very rapidly as the string gets longer. (The * repeat can match 0, 1,
+ 2, 3, or 4 times, and for each of those cases other than 0 or 4, the +
+ repeats can match different numbers of times.) When the remainder of
+ the pattern is such that the entire match is going to fail, PCRE2 has
+ in principle to try every possible variation, and this can take an
extremely long time, even for relatively short strings.
An optimization catches some of the more simple cases such as
@@ -9061,32 +9062,32 @@
(a+)*b
- where a literal character follows. Before embarking on the standard
- matching procedure, PCRE2 checks that there is a "b" later in the sub-
- ject string, and if there is not, it fails the match immediately. How-
- ever, when there is no following literal this optimization cannot be
+ where a literal character follows. Before embarking on the standard
+ matching procedure, PCRE2 checks that there is a "b" later in the sub-
+ ject string, and if there is not, it fails the match immediately. How-
+ ever, when there is no following literal this optimization cannot be
used. You can see the difference by comparing the behaviour of
(a+)*\d
- with the pattern above. The former gives a failure almost instantly
- when applied to a whole line of "a" characters, whereas the latter
+ with the pattern above. The former gives a failure almost instantly
+ when applied to a whole line of "a" characters, whereas the latter
takes an appreciable time with strings longer than about 20 characters.
In many cases, the solution to this kind of performance issue is to use
- an atomic group or a possessive quantifier. This can often reduce mem-
+ an atomic group or a possessive quantifier. This can often reduce mem-
ory requirements as well. As another example, consider this pattern:
([^<]|<(?!inet))+
- It matches from wherever it starts until it encounters "<inet" or the
- end of the data, and is the kind of pattern that might be used when
+ It matches from wherever it starts until it encounters "<inet" or the
+ end of the data, and is the kind of pattern that might be used when
processing an XML file. Each iteration of the outer parentheses matches
- either one character that is not "<" or a "<" that is not followed by
- "inet". However, each time a parenthesis is processed, a backtracking
- position is passed, so this formulation uses a memory frame for each
+ either one character that is not "<" or a "<" that is not followed by
+ "inet". However, each time a parenthesis is processed, a backtracking
+ position is passed, so this formulation uses a memory frame for each
matched character. For a long string, a lot of memory is required. Con-
- sider now this rewritten pattern, which matches exactly the same
+ sider now this rewritten pattern, which matches exactly the same
strings:
([^<]++|<(?!inet))+
@@ -9093,28 +9094,28 @@
This runs much faster, because sequences of characters that do not con-
tain "<" are "swallowed" in one item inside the parentheses, and a pos-
- sessive quantifier is used to stop any backtracking into the runs of
- non-"<" characters. This version also uses a lot less memory because
- entry to a new set of parentheses happens only when a "<" character
- that is not followed by "inet" is encountered (and we assume this is
+ sessive quantifier is used to stop any backtracking into the runs of
+ non-"<" characters. This version also uses a lot less memory because
+ entry to a new set of parentheses happens only when a "<" character
+ that is not followed by "inet" is encountered (and we assume this is
relatively rare).
This example shows that one way of optimizing performance when matching
- long subject strings is to write repeated parenthesized subpatterns to
+ long subject strings is to write repeated parenthesized subpatterns to
match more than one character whenever possible.
SETTING RESOURCE LIMITS
- You can set limits on the amount of processing that takes place when
- matching, and on the amount of heap memory that is used. The default
+ You can set limits on the amount of processing that takes place when
+ matching, and on the amount of heap memory that is used. The default
values of the limits are very large, and unlikely ever to operate. They
- can be changed when PCRE2 is built, and they can also be set when
- pcre2_match() or pcre2_dfa_match() is called. For details of these
- interfaces, see the pcre2build documentation and the section entitled
+ can be changed when PCRE2 is built, and they can also be set when
+ pcre2_match() or pcre2_dfa_match() is called. For details of these
+ interfaces, see the pcre2build documentation and the section entitled
"The match context" in the pcre2api documentation.
- The pcre2test test program has a modifier called "find_limits" which,
- if applied to a subject line, causes it to find the smallest limits
+ The pcre2test test program has a modifier called "find_limits" which,
+ if applied to a subject line, causes it to find the smallest limits
that allow a pattern to match. This is done by repeatedly matching with
different limits.
Modified: code/trunk/doc/pcre2_jit_stack_assign.3
===================================================================
--- code/trunk/doc/pcre2_jit_stack_assign.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2_jit_stack_assign.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -24,7 +24,7 @@
callback a callback function
callback_data a JIT stack or a value to be passed to the callback
.P
-If \fIcallback\fP is NULL and \fIcallback_data\fP is NULL, an internal 32K
+If \fIcallback\fP is NULL and \fIcallback_data\fP is NULL, an internal 32KiB
block on the machine stack is used.
.P
If \fIcallback\fP is NULL and \fIcallback_data\fP is not NULL,
@@ -33,8 +33,9 @@
.P
If \fIcallback\fP not NULL, it is called with \fIcallback_data\fP as an
argument at the start of matching, in order to set up a JIT stack. If the
-result is NULL, the internal 32K stack is used; otherwise the return value must
-be a valid JIT stack, the result of calling \fBpcre2_jit_stack_create()\fP.
+result is NULL, the internal 32KiB stack is used; otherwise the return value
+must be a valid JIT stack, the result of calling
+\fBpcre2_jit_stack_create()\fP.
.P
You may safely use the same JIT stack for multiple patterns, as long as they
are all matched in the same thread. In a multithread application, each thread
Modified: code/trunk/doc/pcre2_jit_stack_create.3
===================================================================
--- code/trunk/doc/pcre2_jit_stack_create.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2_jit_stack_create.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -21,8 +21,8 @@
allocation. The result can be passed to the JIT run-time code by calling
\fBpcre2_jit_stack_assign()\fP to associate the stack with a compiled pattern,
which can then be processed by \fBpcre2_match()\fP or \fBpcre2_jit_match()\fP.
-A maximum stack size of 512K to 1M should be more than enough for any pattern.
-For more details, see the
+A maximum stack size of 512KiB to 1MiB should be more than enough for any
+pattern. For more details, see the
.\" HREF
\fBpcre2jit\fP
.\"
Modified: code/trunk/doc/pcre2api.3
===================================================================
--- code/trunk/doc/pcre2api.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2api.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -909,7 +909,7 @@
less than the limit set by the caller of \fBpcre2_match()\fP or, if no such
limit is set, less than the default.
.P
-The \fBpcre2_match()\fP function starts out using a 20K vector on the system
+The \fBpcre2_match()\fP function starts out using a 20KiB vector on the system
stack for recording backtracking points. The more nested backtracking points
there are (that is, the deeper the search tree), the more memory is needed.
Heap memory is used only if the initial vector is too small. If the heap limit
@@ -1084,7 +1084,7 @@
.P
The default value of 2 for the 8-bit and 16-bit libraries is sufficient for all
but the most massive patterns, since it allows the size of the compiled pattern
-to be up to 64K code units. Larger values allow larger regular expressions to
+to be up to 65535 code units. Larger values allow larger regular expressions to
be compiled by those two libraries, but at the expense of slower matching.
.sp
PCRE2_CONFIG_MATCHLIMIT
Modified: code/trunk/doc/pcre2build.3
===================================================================
--- code/trunk/doc/pcre2build.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2build.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -244,10 +244,10 @@
another (for example, from an opening parenthesis to an alternation
metacharacter). By default, in the 8-bit and 16-bit libraries, two-byte values
are used for these offsets, leading to a maximum size for a compiled pattern of
-around 64K code units. This is sufficient to handle all but the most gigantic
-patterns. Nevertheless, some people do want to process truly enormous patterns,
-so it is possible to compile PCRE2 to use three-byte or four-byte offsets by
-adding a setting such as
+around 64 thousand code units. This is sufficient to handle all but the most
+gigantic patterns. Nevertheless, some people do want to process truly enormous
+patterns, so it is possible to compile PCRE2 to use three-byte or four-byte
+offsets by adding a setting such as
.sp
--with-link-size=3
.sp
@@ -277,7 +277,7 @@
\fBpcre2_dfa_match()\fP matching function, and to JIT matching (though the
counting is done differently).
.P
-The \fBpcre2_match()\fP function starts out using a 20K vector on the system
+The \fBpcre2_match()\fP function starts out using a 20KiB vector on the system
stack to record backtracking points. The more nested backtracking points there
are (that is, the deeper the search tree), the more memory is needed. If the
initial vector is not large enough, heap memory is used, up to a certain limit,
@@ -403,13 +403,13 @@
.sp
\fBpcre2grep\fP uses an internal buffer to hold a "window" on the file it is
scanning, in order to be able to output "before" and "after" lines when it
-finds a match. The starting size of the buffer is controlled by a parameter
-whose default value is 20K. The buffer itself is three times this size, but
-because of the way it is used for holding "before" lines, the longest line that
-is guaranteed to be processable is the parameter size. If a longer line is
-encountered, \fBpcre2grep\fP automatically expands the buffer, up to a
-specified maximum size, whose default is 1M or the starting size, whichever is
-the larger. You can change the default parameter values by adding, for example,
+finds a match. The default starting size of the buffer is 20KiB. The buffer
+itself is three times this size, but because of the way it is used for holding
+"before" lines, the longest line that is guaranteed to be processable is the
+notional buffer size. If a longer line is encountered, \fBpcre2grep\fP
+automatically expands the buffer, up to a specified maximum size, whose default
+is 1MiB or the starting size, whichever is the larger. You can change the
+default parameter values by adding, for example,
.sp
--with-pcre2grep-bufsize=51200
--with-pcre2grep-max-bufsize=2097152
Modified: code/trunk/doc/pcre2grep.1
===================================================================
--- code/trunk/doc/pcre2grep.1 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2grep.1 2018-06-18 14:03:33 UTC (rev 937)
@@ -58,7 +58,7 @@
long lines, a larger buffer may be needed; this is handled by automatically
extending the buffer, up to the limit specified by \fB--max-buffer-size\fP. The
default values for these parameters can be set when \fBpcre2grep\fP is
-built; if nothing is specified, the defaults are set to 20K and 1M
+built; if nothing is specified, the defaults are set to 20KiB and 1MiB
respectively. An error occurs if a line is too long and the buffer can no
longer be expanded.
.P
@@ -66,7 +66,7 @@
allow for buffering "before" and "after" lines. If the buffer size is too
small, fewer than requested "before" and "after" lines may be output.
.P
-Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the greater.
+Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the greater.
BUFSIZ is defined in \fB<stdio.h>\fP. When there is more than one pattern
(specified by the use of \fB-e\fP and/or \fB-f\fP), each pattern is applied to
each line in the order in which they are defined, except that all the \fB-e\fP
Modified: code/trunk/doc/pcre2grep.txt
===================================================================
--- code/trunk/doc/pcre2grep.txt 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2grep.txt 2018-06-18 14:03:33 UTC (rev 937)
@@ -58,8 +58,8 @@
automatically extending the buffer, up to the limit specified by --max-
buffer-size. The default values for these parameters can be set when
pcre2grep is built; if nothing is specified, the defaults are set to
- 20K and 1M respectively. An error occurs if a line is too long and the
- buffer can no longer be expanded.
+ 20KiB and 1MiB respectively. An error occurs if a line is too long and
+ the buffer can no longer be expanded.
The block of memory that is actually used is three times the "buffer
size", to allow for buffering "before" and "after" lines. If the buffer
@@ -66,7 +66,7 @@
size is too small, fewer than requested "before" and "after" lines may
be output.
- Patterns can be no longer than 8K or BUFSIZ bytes, whichever is the
+ Patterns can be no longer than 8KiB or BUFSIZ bytes, whichever is the
greater. BUFSIZ is defined in <stdio.h>. When there is more than one
pattern (specified by the use of -e and/or -f), each pattern is applied
to each line in the order in which they are defined, except that all
Modified: code/trunk/doc/pcre2jit.3
===================================================================
--- code/trunk/doc/pcre2jit.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2jit.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -161,7 +161,7 @@
.rs
.sp
When the compiled JIT code runs, it needs a block of memory to use as a stack.
-By default, it uses 32K on the machine stack. However, some large or
+By default, it uses 32KiB on the machine stack. However, some large or
complicated patterns need more than this. The error PCRE2_ERROR_JIT_STACKLIMIT
is given when there is not enough stack. Three functions are provided for
managing blocks of memory for use as JIT stacks. There is further discussion
@@ -178,8 +178,8 @@
pointer to an opaque structure of type \fBpcre2_jit_stack\fP, or NULL if there
is an error. The \fBpcre2_jit_stack_free()\fP function is used to free a stack
that is no longer needed. (For the technically minded: the address space is
-allocated by mmap or VirtualAlloc.) A maximum stack size of 512K to 1M should
-be more than enough for any pattern.
+allocated by mmap or VirtualAlloc.) A maximum stack size of 512KiB to 1MiB
+should be more than enough for any pattern.
.P
The \fBpcre2_jit_stack_assign()\fP function specifies which stack JIT code
should use. Its arguments are as follows:
@@ -192,7 +192,7 @@
passed to a matching function, its information determines which JIT stack is
used. There are three cases for the values of the other two options:
.sp
- (1) If \fIcallback\fP is NULL and \fIdata\fP is NULL, an internal 32K block
+ (1) If \fIcallback\fP is NULL and \fIdata\fP is NULL, an internal 32KiB block
on the machine stack is used. This is the default when a match
context is created.
.sp
@@ -203,7 +203,7 @@
(3) If \fIcallback\fP is not NULL, it must point to a function that is
called with \fIdata\fP as an argument at the start of matching, in
order to set up a JIT stack. If the return from the callback
- function is NULL, the internal 32K stack is used; otherwise the
+ function is NULL, the internal 32KiB stack is used; otherwise the
return value must be a valid JIT stack, the result of calling
\fBpcre2_jit_stack_create()\fP.
.sp
@@ -265,9 +265,9 @@
Modern operating systems have a nice feature: they can reserve an address space
instead of allocating memory. We can safely allocate memory pages inside this
address space, so the stack could grow without moving memory data (this is
-important because of pointers). Thus we can allocate 1M address space, and use
-only a single memory page (usually 4K) if that is enough. However, we can still
-grow up to 1M anytime if needed.
+important because of pointers). Thus we can allocate 1MiB address space, and
+use only a single memory page (usually 4KiB) if that is enough. However, we can
+still grow up to 1MiB anytime if needed.
.P
(3) Who "owns" a JIT stack?
.sp
@@ -300,7 +300,7 @@
list of patterns.
.P
(6) OK, the stack is for long term memory allocation. But what happens if a
-pattern causes stack overflow with a stack of 1M? Is that 1M kept until the
+pattern causes stack overflow with a stack of 1MiB? Is that 1MiB kept until the
stack is freed?
.sp
Especially on embedded sytems, it might be a good idea to release memory
Modified: code/trunk/doc/pcre2limits.3
===================================================================
--- code/trunk/doc/pcre2limits.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2limits.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -7,12 +7,12 @@
There are some size limitations in PCRE2 but it is hoped that they will never
in practice be relevant.
.P
-The maximum size of a compiled pattern is approximately 64K code units for the
-8-bit and 16-bit libraries if PCRE2 is compiled with the default internal
-linkage size, which is 2 bytes for these libraries. If you want to process
-regular expressions that are truly enormous, you can compile PCRE2 with an
-internal linkage size of 3 or 4 (when building the 16-bit library, 3 is rounded
-up to 4). See the \fBREADME\fP file in the source distribution and the
+The maximum size of a compiled pattern is approximately 64 thousand code units
+for the 8-bit and 16-bit libraries if PCRE2 is compiled with the default
+internal linkage size, which is 2 bytes for these libraries. If you want to
+process regular expressions that are truly enormous, you can compile PCRE2 with
+an internal linkage size of 3 or 4 (when building the 16-bit library, 3 is
+rounded up to 4). See the \fBREADME\fP file in the source distribution and the
.\" HREF
\fBpcre2build\fP
.\"
Modified: code/trunk/doc/pcre2pattern.3
===================================================================
--- code/trunk/doc/pcre2pattern.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2pattern.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -528,7 +528,7 @@
.sp
The sequence \eg followed by a signed or unsigned number, optionally enclosed
in braces, is an absolute or relative backreference. A named backreference
-can be coded as \eg{name}. backreferences are discussed
+can be coded as \eg{name}. Backreferences are discussed
.\" HTML <a href="#backreferences">
.\" </a>
later,
@@ -2243,7 +2243,7 @@
done using alternation, as in the example above, or by a quantifier with a
minimum of zero.
.P
-backreferences of this type cause the group that they reference to be treated
+Backreferences of this type cause the group that they reference to be treated
as an
.\" HTML <a href="#atomicgroup">
.\" </a>
Modified: code/trunk/doc/pcre2perform.3
===================================================================
--- code/trunk/doc/pcre2perform.3 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/doc/pcre2perform.3 2018-06-18 14:03:33 UTC (rev 937)
@@ -34,9 +34,9 @@
.sp
((ab){1,1000}c){1,3}
.sp
-uses over 50K bytes when compiled using the 8-bit library. When PCRE2 is
+uses over 50KiB when compiled using the 8-bit library. When PCRE2 is
compiled with its default internal pointer size of two bytes, the size limit on
-a compiled pattern is 64K code units in the 8-bit and 16-bit libraries, and
+a compiled pattern is 65535 code units in the 8-bit and 16-bit libraries, and
this is reached with the above pattern if the outer repetition is increased
from 3 to 4. PCRE2 can be compiled to use larger internal pointers and thus
handle larger compiled patterns, but it is better to try to rewrite your
@@ -52,14 +52,14 @@
.sp
((ab)(?2){0,999}c)(?1){0,2}
.sp
-reduces the memory requirements to around 16K, and indeed it remains under 20K
-even with the outer repetition increased to 100. However, this kind of pattern
-is not always exactly equivalent, because any captures within subroutine calls
-are lost when the subroutine completes. If this is not a problem, this kind of
-rewriting will allow you to process patterns that PCRE2 cannot otherwise
-handle. The matching performance of the two different versions of the pattern
-are roughly the same. (This applies from release 10.30 - things were different
-in earlier releases.)
+reduces the memory requirements to around 16KiB, and indeed it remains under
+20KiB even with the outer repetition increased to 100. However, this kind of
+pattern is not always exactly equivalent, because any captures within
+subroutine calls are lost when the subroutine completes. If this is not a
+problem, this kind of rewriting will allow you to process patterns that PCRE2
+cannot otherwise handle. The matching performance of the two different versions
+of the pattern are roughly the same. (This applies from release 10.30 - things
+were different in earlier releases.)
.
.
.SH "STACK AND HEAP USAGE AT RUN TIME"
@@ -69,7 +69,7 @@
uses very little system stack at run time. In earlier releases recursive
function calls could use a great deal of stack, and this could cause problems,
but this usage has been eliminated. Backtracking positions are now explicitly
-remembered in memory frames controlled by the code. An initial 20K vector of
+remembered in memory frames controlled by the code. An initial 20KiB vector of
frames is allocated on the system stack (enough for about 100 frames for small
patterns), but if this is insufficient, heap memory is used. The amount of heap
memory can be limited; if the limit is set to zero, only the initial stack
Modified: code/trunk/src/config.h.generic
===================================================================
--- code/trunk/src/config.h.generic 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/src/config.h.generic 2018-06-18 14:03:33 UTC (rev 937)
@@ -134,7 +134,7 @@
/* This limits the amount of memory that may be used while matching a pattern.
It applies to both pcre2_match() and pcre2_dfa_match(). It does not apply
- to JIT matching. The value is in kilobytes. */
+ to JIT matching. The value is in kibibytes (units of 1024 bytes). */
#ifndef HEAP_LIMIT
#define HEAP_LIMIT 20000000
#endif
@@ -141,9 +141,9 @@
/* The value of LINK_SIZE determines the number of bytes used to store links
as offsets within the compiled regex. The default is 2, which allows for
- compiled patterns up to 64K long. This covers the vast majority of cases.
- However, PCRE2 can also be compiled to use 3 or 4 bytes instead. This
- allows for longer patterns in extreme cases. */
+ compiled patterns up to 65535 code units long. This covers the vast
+ majority of cases. However, PCRE2 can also be compiled to use 3 or 4 bytes
+ instead. This allows for longer patterns in extreme cases. */
#ifndef LINK_SIZE
#define LINK_SIZE 2
#endif
Modified: code/trunk/src/config.h.in
===================================================================
--- code/trunk/src/config.h.in 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/src/config.h.in 2018-06-18 14:03:33 UTC (rev 937)
@@ -139,9 +139,9 @@
/* The value of LINK_SIZE determines the number of bytes used to store links
as offsets within the compiled regex. The default is 2, which allows for
- compiled patterns up to 64K long. This covers the vast majority of cases.
- However, PCRE2 can also be compiled to use 3 or 4 bytes instead. This
- allows for longer patterns in extreme cases. */
+ compiled patterns up to 65535 code units long. This covers the vast
+ majority of cases. However, PCRE2 can also be compiled to use 3 or 4 bytes
+ instead. This allows for longer patterns in extreme cases. */
#undef LINK_SIZE
/* Define to the sub-directory where libtool stores uninstalled libraries. */
Modified: code/trunk/src/pcre2_dfa_match.c
===================================================================
--- code/trunk/src/pcre2_dfa_match.c 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/src/pcre2_dfa_match.c 2018-06-18 14:03:33 UTC (rev 937)
@@ -412,7 +412,7 @@
}
/* All sizes are in units of sizeof(int), except for mb->heaplimit, which is in
-kilobytes. */
+kibibytes. */
else
{
Modified: code/trunk/src/pcre2_internal.h
===================================================================
--- code/trunk/src/pcre2_internal.h 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/src/pcre2_internal.h 2018-06-18 14:03:33 UTC (rev 937)
@@ -247,7 +247,7 @@
pcre2_match() is allocated on the system stack, of this size (bytes). The size
must be a multiple of sizeof(PCRE2_SPTR) in all environments, so making it a
multiple of 8 is best. Typical frame sizes are a few hundred bytes (it depends
-on the number of capturing parentheses) so 20K handles quite a few frames. A
+on the number of capturing parentheses) so 20KiB handles quite a few frames. A
larger vector on the heap is obtained for patterns that need more frames. The
maximum size of this can be limited. */
Modified: code/trunk/src/pcre2_match.c
===================================================================
--- code/trunk/src/pcre2_match.c 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/src/pcre2_match.c 2018-06-18 14:03:33 UTC (rev 937)
@@ -6283,7 +6283,7 @@
/* If a pattern has very many capturing parentheses, the frame size may be very
large. Ensure that there are at least 10 available frames by getting an initial
vector on the heap if necessary, except when the heap limit prevents this. Get
-fewer if possible. (The heap limit is in kilobytes.) */
+fewer if possible. (The heap limit is in kibibytes.) */
if (frame_size <= START_FRAMES_SIZE/10)
{
Modified: code/trunk/src/pcre2grep.c
===================================================================
--- code/trunk/src/pcre2grep.c 2018-06-17 14:13:28 UTC (rev 936)
+++ code/trunk/src/pcre2grep.c 2018-06-18 14:03:33 UTC (rev 937)
@@ -416,7 +416,7 @@
{ OP_NODATA, N_LBUFFER, NULL, "line-buffered", "use line buffering" },
{ OP_NODATA, N_LOFFSETS, NULL, "line-offsets", "output line numbers and offsets, not text" },
{ OP_STRING, N_LOCALE, &locale, "locale=locale", "use the named locale" },
- { OP_SIZE, N_H_LIMIT, &heap_limit, "heap-limit=number", "set PCRE2 heap limit option (kilobytes)" },
+ { OP_SIZE, N_H_LIMIT, &heap_limit, "heap-limit=number", "set PCRE2 heap limit option (kibibytes)" },
{ OP_U32NUMBER, N_M_LIMIT, &match_limit, "match-limit=number", "set PCRE2 match limit option" },
{ OP_U32NUMBER, N_M_LIMIT_DEP, &depth_limit, "depth-limit=number", "set PCRE2 depth limit option" },
{ OP_U32NUMBER, N_M_LIMIT_DEP, &depth_limit, "recursion-limit=number", "obsolete synonym for depth-limit" },
Modified: code/trunk/testdata/grepinput
===================================================================
(Binary files differ)
Modified: code/trunk/testdata/grepoutput
===================================================================
(Binary files differ)
