Revision: 930
http://vcs.pcre.org/viewvc?view=rev&revision=930
Author: ph10
Date: 2012-02-24 12:05:54 +0000 (Fri, 24 Feb 2012)
Log Message:
-----------
Improve documentation for (*MARK); update HTML.
Modified Paths:
--------------
code/trunk/doc/html/index.html
code/trunk/doc/html/pcreapi.html
code/trunk/doc/html/pcrejit.html
code/trunk/doc/html/pcrepartial.html
code/trunk/doc/html/pcrepattern.html
code/trunk/doc/html/pcretest.html
code/trunk/doc/pcre.txt
code/trunk/doc/pcreapi.3
code/trunk/doc/pcrepattern.3
code/trunk/doc/pcretest.1
code/trunk/doc/pcretest.txt
Modified: code/trunk/doc/html/index.html
===================================================================
--- code/trunk/doc/html/index.html 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/html/index.html 2012-02-24 12:05:54 UTC (rev 930)
@@ -1,10 +1,10 @@
<html>
-<!-- This is a manually maintained file that is the root of the HTML version of
- the PCRE documentation. When the HTML documents are built from the man
- page versions, the entire doc/html directory is emptied, this file is then
- copied into doc/html/index.html, and the remaining files therein are
+<!-- This is a manually maintained file that is the root of the HTML version of
+ the PCRE documentation. When the HTML documents are built from the man
+ page versions, the entire doc/html directory is emptied, this file is then
+ copied into doc/html/index.html, and the remaining files therein are
created by the 132html script.
--->
+-->
<head>
<title>PCRE specification</title>
</head>
@@ -86,11 +86,11 @@
</table>
<p>
-There are also individual pages that summarize the interface for each function
+There are also individual pages that summarize the interface for each function
in the library. There is a single page for each pair of 8-bit/16-bit functions.
</p>
-<table>
+<table>
<tr><td><a href="pcre_assign_jit_stack.html">pcre_assign_jit_stack</a></td>
<td> Assign stack for JIT matching</td></tr>
@@ -153,7 +153,7 @@
<tr><td><a href="pcre_maketables.html">pcre_maketables</a></td>
<td> Build character tables in current locale</td></tr>
-
+
<tr><td><a href="pcre_pattern_to_host_byte_order.html">pcre_pattern_to_host_byte_order</a></td>
<td> Convert compiled pattern to host byte order if necessary</td></tr>
Modified: code/trunk/doc/html/pcreapi.html
===================================================================
--- code/trunk/doc/html/pcreapi.html 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/html/pcreapi.html 2012-02-24 12:05:54 UTC (rev 930)
@@ -524,7 +524,7 @@
the pattern, the contents of the <i>options</i> argument specifies their
settings at the start of compilation and execution. The PCRE_ANCHORED,
PCRE_BSR_<i>xxx</i>, PCRE_NEWLINE_<i>xxx</i>, PCRE_NO_UTF8_CHECK, and
-PCRE_NO_START_OPT options can be set at the time of matching as well as at
+PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
compile time.
</P>
<P>
@@ -949,12 +949,18 @@
<b>pcre_dfa_exec()</b>, it must set up its own <b>pcre_extra</b> block.
</P>
<P>
-The second argument of <b>pcre_study()</b> contains option bits. There is only
-one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-time
-compiler is available, the pattern is further compiled into machine code that
-executes much faster than the <b>pcre_exec()</b> matching function. If
-the just-in-time compiler is not available, this option is ignored. All other
-bits in the <i>options</i> argument must be zero.
+The second argument of <b>pcre_study()</b> contains option bits. There are three
+options:
+<pre>
+ PCRE_STUDY_JIT_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+</pre>
+If any of these are set, and the just-in-time compiler is available, the
+pattern is further compiled into machine code that executes much faster than
+the <b>pcre_exec()</b> interpretive matching function. If the just-in-time
+compiler is not available, these options are ignored. All other bits in the
+<i>options</i> argument must be zero.
</P>
<P>
JIT compilation is a heavyweight optimization. It can take some time for
@@ -979,8 +985,8 @@
study data by calling <b>pcre_free_study()</b>. This function was added to the
API for release 8.20. For earlier versions, the memory could be freed with
<b>pcre_free()</b>, just like the pattern itself. This will still work in cases
-where PCRE_STUDY_JIT_COMPILE is not used, but it is advisable to change to the
-new function when convenient.
+where JIT optimization is not used, but it is advisable to change to the new
+function when convenient.
</P>
<P>
This is a typical way in which <b>pcre_study</b>() is used (except that in a
@@ -1016,14 +1022,12 @@
</P>
<P>
These two optimizations apply to both <b>pcre_exec()</b> and
-<b>pcre_dfa_exec()</b>. However, they are not used by <b>pcre_exec()</b> if
-<b>pcre_study()</b> is called with the PCRE_STUDY_JIT_COMPILE option, and
-just-in-time compiling is successful. The optimizations can be disabled by
-setting the PCRE_NO_START_OPTIMIZE option when calling <b>pcre_exec()</b> or
-<b>pcre_dfa_exec()</b>. You might want to do this if your pattern contains
-callouts or (*MARK) (which cannot be handled by the JIT compiler), and you want
-to make use of these facilities in cases where matching fails. See the
-discussion of PCRE_NO_START_OPTIMIZE
+<b>pcre_dfa_exec()</b>, and the information is also used by the JIT compiler.
+The optimizations can be disabled by setting the PCRE_NO_START_OPTIMIZE option
+when calling <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>, but if this is done,
+JIT execution is also disabled. You might want to do this if your pattern
+contains callouts or (*MARK) and you want to make use of these facilities in
+cases where matching fails. See the discussion of PCRE_NO_START_OPTIMIZE
<a href="#execoptions">below.</a>
<a name="localesupport"></a></P>
<br><a name="SEC14" href="#TOC1">LOCALE SUPPORT</a><br>
@@ -1199,20 +1203,19 @@
<pre>
PCRE_INFO_JIT
</pre>
-Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE option, and
+Return 1 if the pattern was studied with one of the JIT options, and
just-in-time compiling was successful. The fourth argument should point to an
<b>int</b> variable. A return value of 0 means that JIT support is not available
-in this version of PCRE, or that the pattern was not studied with the
-PCRE_STUDY_JIT_COMPILE option, or that the JIT compiler could not handle this
-particular pattern. See the
+in this version of PCRE, or that the pattern was not studied with a JIT option,
+or that the JIT compiler could not handle this particular pattern. See the
<a href="pcrejit.html"><b>pcrejit</b></a>
documentation for details of what can and cannot be handled.
<pre>
PCRE_INFO_JITSIZE
</pre>
-If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,
-return the size of the JIT compiled code, otherwise return zero. The fourth
-argument should point to a <b>size_t</b> variable.
+If the pattern was successfully studied with a JIT option, return the size of
+the JIT compiled code, otherwise return zero. The fourth argument should point
+to a <b>size_t</b> variable.
<pre>
PCRE_INFO_LASTLITERAL
</pre>
@@ -1439,22 +1442,22 @@
"PCRE_UCHAR16 **".
</P>
<P>
-The <i>flags</i> field is a bitmap that specifies which of the other fields
-are set. The flag bits are:
+The <i>flags</i> field is used to specify which of the other fields are set. The
+flag bits are:
<pre>
- PCRE_EXTRA_STUDY_DATA
+ PCRE_EXTRA_CALLOUT_DATA
PCRE_EXTRA_EXECUTABLE_JIT
+ PCRE_EXTRA_MARK
PCRE_EXTRA_MATCH_LIMIT
PCRE_EXTRA_MATCH_LIMIT_RECURSION
- PCRE_EXTRA_CALLOUT_DATA
+ PCRE_EXTRA_STUDY_DATA
PCRE_EXTRA_TABLES
- PCRE_EXTRA_MARK
</pre>
Other flag bits should be set to zero. The <i>study_data</i> field and sometimes
the <i>executable_jit</i> field are set in the <b>pcre_extra</b> block that is
returned by <b>pcre_study()</b>, together with the appropriate flag bits. You
-should not set these yourself, but you may add to the block by setting the
-other fields and their corresponding flag bits.
+should not set these yourself, but you may add to the block by setting other
+fields and their corresponding flag bits.
</P>
<P>
The <i>match_limit</i> field provides a means of preventing PCRE from using up a
@@ -1472,11 +1475,10 @@
</P>
<P>
When <b>pcre_exec()</b> is called with a pattern that was successfully studied
-with the PCRE_STUDY_JIT_COMPILE option, the way that the 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 <i>match_limit</i> value
-is also used in this case (but in a different way) to limit how long the
-matching can continue.
+with a JIT option, the way that the 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 <i>match_limit</i> value is also used in this case
+(but in a different way) to limit how long the matching can continue.
</P>
<P>
The default value for the limit can be set when PCRE is built; the default
@@ -1497,8 +1499,7 @@
Limiting the recursion depth limits the amount of machine stack that can be
used, or, when PCRE has been compiled to use memory on the heap instead of the
stack, the amount of heap memory that can be used. This limit is not relevant,
-and is ignored, if the pattern was successfully studied with
-PCRE_STUDY_JIT_COMPILE.
+and is ignored, when matching is done using JIT compiled code.
</P>
<P>
The default value for <i>match_limit_recursion</i> can be set when PCRE is
@@ -1549,16 +1550,16 @@
The unused bits of the <i>options</i> argument for <b>pcre_exec()</b> must be
zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_<i>xxx</i>,
PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
-PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
-PCRE_PARTIAL_HARD.
+PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
+PCRE_PARTIAL_SOFT.
</P>
<P>
-If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE option,
-the only supported options for JIT execution are PCRE_NO_UTF8_CHECK,
-PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NOTEMPTY_ATSTART. Note in
-particular that partial matching is not supported. If an unsupported option is
-used, JIT execution is disabled and the normal interpretive code in
-<b>pcre_exec()</b> is run.
+If the pattern was successfully studied with one of the just-in-time (JIT)
+compile options, the only supported options for JIT execution are
+PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
+PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
+unsupported option is used, JIT execution is disabled and the normal
+interpretive code in <b>pcre_exec()</b> is run.
<pre>
PCRE_ANCHORED
</pre>
@@ -1681,7 +1682,8 @@
"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. If
PCRE_NO_START_OPTIMIZE is set at compile time, it cannot be unset at matching
-time.
+time. The use of PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set,
+matching is always done using interpretively.
</P>
<P>
Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching operation.
@@ -2067,9 +2069,9 @@
<pre>
PCRE_ERROR_JIT_STACKLIMIT (-27)
</pre>
-This error is returned when a pattern that was successfully studied using the
-PCRE_STUDY_JIT_COMPILE option is being matched, but the memory available for
-the just-in-time processing stack is not large enough. See the
+This error is returned when a pattern that was successfully studied using a
+JIT compile option is being matched, but the memory available for the
+just-in-time processing stack is not large enough. See the
<a href="pcrejit.html"><b>pcrejit</b></a>
documentation for more details.
<pre>
@@ -2599,7 +2601,7 @@
</P>
<br><a name="SEC26" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 21 January 2012
+Last updated: 22 February 2012
<br>
Copyright © 1997-2012 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcrejit.html
===================================================================
--- code/trunk/doc/html/pcrejit.html 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/html/pcrejit.html 2012-02-24 12:05:54 UTC (rev 930)
@@ -62,16 +62,14 @@
MIPS 32-bit
Power PC 32-bit and 64-bit
</pre>
-The Power PC support is designated as experimental because it has not been
-fully tested. If --enable-jit is set on an unsupported platform, compilation
-fails.
+If --enable-jit is set on an unsupported platform, compilation fails.
</P>
<P>
A program that is linked with PCRE 8.20 or later can tell if JIT support is
available by calling <b>pcre_config()</b> with the PCRE_CONFIG_JIT option. The
result is 1 when JIT is available, and 0 otherwise. However, a simple program
does not need to check this in order to use JIT. The API is implemented in a
-way that falls back to the ordinary PCRE code if JIT is not available.
+way that falls back to the interpretive code if JIT is not available.
</P>
<P>
If your program may sometimes be linked with versions of PCRE that are older
@@ -88,7 +86,7 @@
<b>pcre_exec()</b>.
(2) Use <b>pcre_free_study()</b> to free the <b>pcre_extra</b> block when it is
- no longer needed instead of just freeing it yourself. This
+ no longer needed, instead of just freeing it yourself. This
ensures that any JIT data is also freed.
</pre>
For a program that may be linked with pre-8.20 versions of PCRE, you can insert
@@ -106,32 +104,55 @@
pcre_free(study_ptr);
#endif
</pre>
+PCRE_STUDY_JIT_COMPILE requests the JIT compiler to generate code for complete
+matches. If you want to run partial matches using the PCRE_PARTIAL_HARD or
+PCRE_PARTIAL_SOFT options of <b>pcre_exec()</b>, you should set one or both of
+the following options in addition to, or instead of, PCRE_STUDY_JIT_COMPILE
+when you call <b>pcre_study()</b>:
+<pre>
+ PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+</pre>
+The JIT compiler generates different optimized code for each of the three
+modes (normal, soft partial, hard partial). When <b>pcre_exec()</b> is called,
+the appropriate code is run if it is available. Otherwise, the pattern is
+matched using interpretive code.
+</P>
+<P>
In some circumstances you may need to call additional functions. These are
described in the section entitled
<a href="#stackcontrol">"Controlling the JIT stack"</a>
below.
</P>
<P>
-If JIT support is not available, PCRE_STUDY_JIT_COMPILE is ignored, and no JIT
-data is set up. Otherwise, the compiled pattern is passed to the JIT compiler,
-which turns it into machine code that executes much faster than the normal
-interpretive code. When <b>pcre_exec()</b> is passed a <b>pcre_extra</b> block
-containing a pointer to JIT code, it obeys that instead of the normal code. The
-result is identical, but the code runs much faster.
+If JIT support is not available, PCRE_STUDY_JIT_COMPILE etc. are ignored, and
+no JIT data is created. Otherwise, the compiled pattern is passed to the JIT
+compiler, which turns it into machine code that executes much faster than the
+normal interpretive code. When <b>pcre_exec()</b> is passed a <b>pcre_extra</b>
+block containing a pointer to JIT code of the appropriate mode (normal or
+hard/soft partial), it obeys that code instead of running the interpreter. The
+result is identical, but the compiled JIT code runs much faster.
</P>
<P>
There are some <b>pcre_exec()</b> options that are not supported for JIT
execution. There are also some pattern items that JIT cannot handle. Details
are given below. In both cases, execution automatically falls back to the
-interpretive code.
+interpretive code. If you want to know whether JIT was actually used for a
+particular match, you should arrange for a JIT callback function to be set up
+as described in the section entitled
+<a href="#stackcontrol">"Controlling the JIT stack"</a>
+below, even if you do not need to supply a non-default JIT stack. Such a
+callback function is called whenever JIT code is about to be obeyed. If the
+execution options are not right for JIT execution, the callback function is not
+obeyed.
</P>
<P>
If the JIT compiler finds an unsupported item, no JIT data is generated. You
can find out if JIT execution is available after studying a pattern by calling
<b>pcre_fullinfo()</b> with the PCRE_INFO_JIT option. A result of 1 means that
JIT compilation was successful. A result of 0 means that JIT support is not
-available, or the pattern was not studied with PCRE_STUDY_JIT_COMPILE, or the
-JIT compiler was not able to handle the pattern.
+available, or the pattern was not studied with PCRE_STUDY_JIT_COMPILE etc., or
+the JIT compiler was not able to handle the pattern.
</P>
<P>
Once a pattern has been studied, with or without JIT, it can be used as many
@@ -140,9 +161,8 @@
<br><a name="SEC5" href="#TOC1">UNSUPPORTED OPTIONS AND PATTERN ITEMS</a><br>
<P>
The only <b>pcre_exec()</b> options that are supported for JIT execution are
-PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and
-PCRE_NOTEMPTY_ATSTART. Note in particular that partial matching is not
-supported.
+PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
+PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT.
</P>
<P>
The unsupported pattern items are:
@@ -221,8 +241,8 @@
void *data
</pre>
The <i>extra</i> argument must be the result of studying a pattern with
-PCRE_STUDY_JIT_COMPILE. There are three cases for the values of the other two
-options:
+PCRE_STUDY_JIT_COMPILE etc. 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
on the machine stack is used.
@@ -230,26 +250,38 @@
(2) If <i>callback</i> is NULL and <i>data</i> is not NULL, <i>data</i> must be
a valid JIT stack, the result of calling <b>pcre_jit_stack_alloc()</b>.
- (3) If <i>callback</i> 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 result is NULL, the internal 32K stack
- is used; otherwise the return value must be a valid JIT stack,
- the result of calling <b>pcre_jit_stack_alloc()</b>.
+ (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
+ return value must be a valid JIT stack, the result of calling
+ <b>pcre_jit_stack_alloc()</b>.
</pre>
-You may safely assign the same JIT stack to more than one pattern, as long as
-they are all matched sequentially in the same thread. In a multithread
-application, each thread must use its own JIT stack.
+A callback function is obeyed whenever JIT code is about to be run; it is not
+obeyed when <b>pcre_exec()</b> is called with options that are incompatible for
+JIT execution. A callback function can therefore be used to determine whether a
+match operation was executed by JIT or by the interpreter.
</P>
<P>
-Strictly speaking, even more is allowed. You can assign the same stack to any
-number of patterns as long as they are not used for matching by multiple
+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 all matched
+sequentially in the same thread. 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.
+</P>
+<P>
+Strictly speaking, even more is allowed. You can assign the same non-NULL stack
+to any number of patterns as long as they are not used for matching by multiple
threads at the same time. For example, you can assign the same stack to all
compiled patterns, and use a global mutex in the callback to wait until the
-stack is available for use. However, this is an inefficient solution, and
-not recommended.
+stack is available for use. However, this is an inefficient solution, and not
+recommended.
</P>
<P>
-This is a suggestion for how a typical multithreaded program might operate:
+This is a suggestion for how a multithreaded program that needs to set up
+non-default JIT stacks might operate:
<pre>
During thread initalization
thread_local_var = pcre_jit_stack_alloc(...)
@@ -263,7 +295,7 @@
All the functions described in this section do nothing if JIT is not available,
and <b>pcre_assign_jit_stack()</b> does nothing unless the <b>extra</b> argument
is non-NULL and points to a <b>pcre_extra</b> block that is the result of a
-successful study with PCRE_STUDY_JIT_COMPILE.
+successful study with PCRE_STUDY_JIT_COMPILE etc.
<a name="stackfaq"></a></P>
<br><a name="SEC9" href="#TOC1">JIT STACK FAQ</a><br>
<P>
@@ -329,11 +361,11 @@
stack is freed?
<br>
<br>
-Especially on embedded sytems, it might be a good idea to release
-memory 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 memory (shrinking the
-stack) would be a good idea if someone needs this.
+Especially on embedded sytems, it might be a good idea to release memory
+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 memory (shrinking the stack) would
+be a good idea if someone needs this.
</P>
<P>
(7) This is too much of a headache. Isn't there any better solution for JIT
@@ -383,7 +415,7 @@
</P>
<br><a name="SEC13" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 08 January 2012
+Last updated: 23 February 2012
<br>
Copyright © 1997-2012 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcrepartial.html
===================================================================
--- code/trunk/doc/html/pcrepartial.html 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/html/pcrepartial.html 2012-02-24 12:05:54 UTC (rev 930)
@@ -58,9 +58,19 @@
are set, PCRE_PARTIAL_HARD takes precedence.
</P>
<P>
-Setting a partial matching option disables the use of any just-in-time code
-that was set up by studying the compiled pattern with the
-PCRE_STUDY_JIT_COMPILE option. It also disables two of PCRE's standard
+If you want to use partial matching with just-in-time optimized code, you must
+call <b>pcre_study()</b> or <b>pcre16_study()</b> with one or both of these
+options:
+<pre>
+ PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+</pre>
+PCRE_STUDY_JIT_COMPILE should also be set if you are going to run non-partial
+matches on the same pattern. If the appropriate JIT study mode has not been set
+for a match, the interpretive matching code is used.
+</P>
+<P>
+Setting a partial matching option disables two of PCRE's standard
optimizations. PCRE remembers the last literal data unit in a pattern, and
abandons matching immediately if it is not present in the subject string. This
optimization cannot be used for a subject string that might match only
@@ -435,7 +445,7 @@
</P>
<br><a name="SEC11" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 21 January 2012
+Last updated: 18 February 2012
<br>
Copyright © 1997-2012 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcrepattern.html
===================================================================
--- code/trunk/doc/html/pcrepattern.html 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/html/pcrepattern.html 2012-02-24 12:05:54 UTC (rev 930)
@@ -2565,7 +2565,10 @@
that is, if the closing parenthesis immediately follows the colon, the effect
is as if the colon were not there. Any number of these verbs may occur in a
pattern.
-</P>
+<a name="nooptimize"></a></P>
+<br><b>
+Optimizations that affect backtracking verbs
+</b><br>
<P>
PCRE contains some optimizations that are used to speed up matching by running
some checks at the start of each match attempt. For example, it may know the
@@ -2574,7 +2577,12 @@
included backtracking verbs will not, of course, be processed. You can suppress
the start-of-match optimizations by setting the PCRE_NO_START_OPTIMIZE option
when calling <b>pcre_compile()</b> or <b>pcre_exec()</b>, or by starting the
-pattern with (*NO_START_OPT).
+pattern with (*NO_START_OPT). There is more discussion of this option in the
+section entitled
+<a href="pcreapi.html#execoptions">"Option bits for <b>pcre_exec()</b>"</a>
+in the
+<a href="pcreapi.html"><b>pcreapi</b></a>
+documentation.
</P>
<P>
Experiments with Perl suggest that it too has similar optimizations, sometimes
@@ -2662,10 +2670,16 @@
No match, mark = B
</pre>
Note that in this unanchored example the mark is retained from the match
-attempt that started at the letter "X". Subsequent match attempts starting at
-"P" and then with an empty string do not get as far as the (*MARK) item, but
-nevertheless do not reset it.
+attempt that started at the letter "X" in the subject. Subsequent match
+attempts starting at "P" and then with an empty string do not get as far as the
+(*MARK) item, but nevertheless do not reset it.
</P>
+<P>
+If you are interested in (*MARK) values after failed matches, you should
+probably set the PCRE_NO_START_OPTIMIZE option
+<a href="#nooptimize">(see above)</a>
+to ensure that the match is always attempted.
+</P>
<br><b>
Verbs that act after backtracking
</b><br>
@@ -2843,7 +2857,7 @@
</P>
<br><a name="SEC28" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 09 January 2012
+Last updated: 24 February 2012
<br>
Copyright © 1997-2012 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcretest.html
===================================================================
--- code/trunk/doc/html/pcretest.html 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/html/pcretest.html 2012-02-24 12:05:54 UTC (rev 930)
@@ -164,15 +164,31 @@
<P>
<b>-s</b> or <b>-s+</b>
Behave as if each pattern has the <b>/S</b> modifier; in other words, force each
-pattern to be studied. If <b>-s+</b> is used, the PCRE_STUDY_JIT_COMPILE flag is
+pattern to be studied. If <b>-s+</b> is used, all the JIT compile options are
passed to <b>pcre[16]_study()</b>, causing just-in-time optimization to be set
-up if it is available. If the <b>/I</b> or <b>/D</b> option is present on a
-pattern (requesting output about the compiled pattern), information about the
-result of studying is not included when studying is caused only by <b>-s</b> and
-neither <b>-i</b> nor <b>-d</b> is present on the command line. This behaviour
-means that the output from tests that are run with and without <b>-s</b> should
-be identical, except when options that output information about the actual
-running of a match are set.
+up if it is available, for both full and partial matching. Specific JIT compile
+options can be selected by following <b>-s+</b> with a digit in the range 1 to
+7, which selects the JIT compile modes as follows:
+<pre>
+ 1 normal match only
+ 2 soft partial match only
+ 3 normal match and soft partial match
+ 4 hard partial match only
+ 6 soft and hard partial match
+ 7 all three modes (default)
+</pre>
+If <b>-s++</b> is used instead of <b>-s+</b> (with or without a following digit),
+the text "(JIT)" is added to the first output line after a match or no match
+when JIT-compiled code was actually used.
+</P>
+<P>
+If the <b>/I</b> or <b>/D</b> option is present on a pattern (requesting output
+about the compiled pattern), information about the result of studying is not
+included when studying is caused only by <b>-s</b> and neither <b>-i</b> nor
+<b>-d</b> is present on the command line. This behaviour means that the output
+from tests that are run with and without <b>-s</b> should be identical, except
+when options that output information about the actual running of a match are
+set.
<br>
<br>
The <b>-M</b>, <b>-t</b>, and <b>-tm</b> options, which give information about
@@ -356,7 +372,7 @@
twice, the same action is taken for captured substrings. In each case the
remainder is output on the following line with a plus character following the
capture number. Note that this modifier must not immediately follow the /S
-modifier because /S+ has another meaning.
+modifier because /S+ and /S++ have other meanings.
</P>
<P>
The <b>/=</b> modifier requests that the values of all potential captured
@@ -435,13 +451,30 @@
</P>
<P>
If the <b>/S</b> modifier is immediately followed by a + character, the call to
-<b>pcre[16]_study()</b> is made with the PCRE_STUDY_JIT_COMPILE option,
-requesting just-in-time optimization support if it is available. Note that
-there is also a <b>/+</b> modifier; it must not be given immediately after
-<b>/S</b> because this will be misinterpreted. If JIT studying is successful, it
-will automatically be used when <b>pcre[16]_exec()</b> is run, except when
-incompatible run-time options are specified. These include the partial matching
-options; a complete list is given in the
+<b>pcre[16]_study()</b> is made with all the JIT study options, requesting
+just-in-time optimization support if it is available, for both normal and
+partial matching. If you want to restrict the JIT compiling modes, you can
+follow <b>/S+</b> with a digit in the range 1 to 7:
+<pre>
+ 1 normal match only
+ 2 soft partial match only
+ 3 normal match and soft partial match
+ 4 hard partial match only
+ 6 soft and hard partial match
+ 7 all three modes (default)
+</pre>
+If <b>/S++</b> is used instead of <b>/S+</b> (with or without a following digit),
+the text "(JIT)" is added to the first output line after a match or no match
+when JIT-compiled code was actually used.
+</P>
+<P>
+Note that there is also an independent <b>/+</b> modifier; it must not be given
+immediately after <b>/S</b> or <b>/S+</b> because this will be misinterpreted.
+</P>
+<P>
+If JIT studying is successful, the compiled JIT code will automatically be used
+when <b>pcre[16]_exec()</b> is run, except when incompatible run-time options
+are specified. For more details, see the
<a href="pcrejit.html"><b>pcrejit</b></a>
documentation. See also the <b>\J</b> escape sequence below for a way of
setting the size of the JIT stack.
@@ -923,7 +956,7 @@
</P>
<br><a name="SEC16" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 14 January 2012
+Last updated: 21 February 2012
<br>
Copyright © 1997-2012 University of Cambridge.
<br>
Modified: code/trunk/doc/pcre.txt
===================================================================
--- code/trunk/doc/pcre.txt 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/pcre.txt 2012-02-24 12:05:54 UTC (rev 930)
@@ -138,8 +138,8 @@
Last updated: 10 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCRE(3) PCRE(3)
@@ -463,8 +463,8 @@
Last updated: 08 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREBUILD(3) PCREBUILD(3)
@@ -859,8 +859,8 @@
Last updated: 07 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREMATCHING(3) PCREMATCHING(3)
@@ -1066,8 +1066,8 @@
Last updated: 08 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREAPI(3) PCREAPI(3)
@@ -1511,8 +1511,8 @@
different parts of the pattern, the contents of the options argument
specifies their settings at the start of compilation and execution. The
PCRE_ANCHORED, PCRE_BSR_xxx, PCRE_NEWLINE_xxx, PCRE_NO_UTF8_CHECK, and
- PCRE_NO_START_OPT options can be set at the time of matching as well as
- at compile time.
+ PCRE_NO_START_OPTIMIZE options can be set at the time of matching as
+ well as at compile time.
If errptr is NULL, pcre_compile() returns NULL immediately. Otherwise,
if compilation of a pattern fails, pcre_compile() returns NULL, and
@@ -1921,13 +1921,19 @@
wants to pass any of the other fields to pcre_exec() or
pcre_dfa_exec(), it must set up its own pcre_extra block.
- The second argument of pcre_study() contains option bits. There is only
- one option: PCRE_STUDY_JIT_COMPILE. If this is set, and the just-in-
- time compiler is available, the pattern is further compiled into
- machine code that executes much faster than the pcre_exec() matching
- function. If the just-in-time compiler is not available, this option is
- ignored. All other bits in the options argument must be zero.
+ The second argument of pcre_study() contains option bits. There are
+ three options:
+ PCRE_STUDY_JIT_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+
+ If any of these are set, and the just-in-time compiler is available,
+ the pattern is further compiled into machine code that executes much
+ faster than the pcre_exec() interpretive matching function. If the
+ just-in-time compiler is not available, these options are ignored. All
+ other bits in the options argument must be zero.
+
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
@@ -1947,8 +1953,8 @@
the study data by calling pcre_free_study(). This function was added to
the API for release 8.20. For earlier versions, the memory could be
freed with pcre_free(), just like the pattern itself. This will still
- work in cases where PCRE_STUDY_JIT_COMPILE is not used, but it is
- advisable to change to the new function when convenient.
+ work in cases where JIT optimization is not used, but it is advisable
+ to change to the new function when convenient.
This is a typical way in which pcre_study() is used (except that in a
real application there should be tests for errors):
@@ -1981,71 +1987,70 @@
which to start matching. (In 16-bit mode, the bitmap is used for 16-bit
values less than 256.)
- These two optimizations apply to both pcre_exec() and pcre_dfa_exec().
- However, they are not used by pcre_exec() if pcre_study() is called
- with the PCRE_STUDY_JIT_COMPILE option, and just-in-time compiling is
- successful. The optimizations can be disabled by setting the
- PCRE_NO_START_OPTIMIZE option when calling pcre_exec() or
- pcre_dfa_exec(). You might want to do this if your pattern contains
- callouts or (*MARK) (which cannot be handled by the JIT compiler), and
- you want to make use of these facilities in cases where matching fails.
- See the discussion of PCRE_NO_START_OPTIMIZE below.
+ These two optimizations apply to both pcre_exec() and pcre_dfa_exec(),
+ and the information is also used by the JIT compiler. The optimiza-
+ tions can be disabled by setting the PCRE_NO_START_OPTIMIZE option when
+ calling pcre_exec() or pcre_dfa_exec(), but if this is done, JIT execu-
+ tion is also disabled. You might want to do this if your pattern con-
+ tains callouts or (*MARK) and you want to make use of these facilities
+ in cases where matching fails. See the discussion of
+ PCRE_NO_START_OPTIMIZE below.
LOCALE SUPPORT
- PCRE handles caseless matching, and determines whether characters are
- letters, digits, or whatever, by reference to a set of tables, indexed
- by character value. When running in UTF-8 mode, this applies only to
- characters with codes less than 128. By default, higher-valued codes
+ PCRE handles caseless matching, and determines whether characters are
+ letters, digits, or whatever, by reference to a set of tables, indexed
+ by character value. When running in UTF-8 mode, this applies only to
+ characters with codes less than 128. By default, higher-valued codes
never match escapes such as \w or \d, but they can be tested with \p if
- PCRE is built with Unicode character property support. Alternatively,
- the PCRE_UCP option can be set at compile time; this causes \w and
+ PCRE is built with Unicode character property support. Alternatively,
+ the PCRE_UCP option can be set at compile time; this causes \w and
friends to use Unicode property support instead of built-in tables. The
use of locales with Unicode is discouraged. If you are handling charac-
- ters with codes greater than 128, you should either use UTF-8 and Uni-
+ ters with codes greater than 128, you should either use UTF-8 and Uni-
code, or use locales, but not try to mix the two.
- PCRE contains an internal set of tables that are used when the final
- argument of pcre_compile() is NULL. These are sufficient for many
+ PCRE contains an internal set of tables that are used when the final
+ argument of pcre_compile() is NULL. These are sufficient for many
applications. Normally, the internal tables recognize only ASCII char-
acters. However, when PCRE is built, it is possible to cause the inter-
nal tables to be rebuilt in the default "C" locale of the local system,
which may cause them to be different.
- The internal tables can always be overridden by tables supplied by the
+ The internal tables can always be overridden by tables supplied by the
application that calls PCRE. These may be created in a different locale
- from the default. As more and more applications change to using Uni-
+ 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 pcre_maketables() function,
- which has no arguments, in the relevant locale. The result can then be
- passed to pcre_compile() or pcre_exec() as often as necessary. 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 pcre_maketables() function,
+ which has no arguments, in the relevant locale. The result can then be
+ passed to pcre_compile() or pcre_exec() as often as necessary. 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");
tables = pcre_maketables();
re = pcre_compile(..., tables);
- The locale name "fr_FR" is used on Linux and other Unix-like systems;
+ 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".
- When pcre_maketables() runs, the tables are built in memory that is
- obtained via pcre_malloc. It is the caller's responsibility to ensure
- that the memory containing the tables remains available for as long as
+ When pcre_maketables() runs, the tables are built in memory that is
+ obtained via pcre_malloc. 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 to pcre_compile() is saved with the compiled
- pattern, and the same tables are used via this pointer by pcre_study()
+ pattern, and the same tables are used via this pointer by pcre_study()
and normally also by pcre_exec(). Thus, by default, for any single pat-
tern, compilation, studying and matching all happen in the same locale,
but different patterns can be compiled in different locales.
- It is possible to pass a table pointer or NULL (indicating the use of
- the internal tables) to pcre_exec(). Although not intended for this
- purpose, this facility could be used to match a pattern in a different
+ It is possible to pass a table pointer or NULL (indicating the use of
+ the internal tables) to pcre_exec(). Although not intended for this
+ purpose, this facility could be used to match a pattern in a different
locale from the one in which it was compiled. Passing table pointers at
run time is discussed below in the section on matching a pattern.
@@ -2055,15 +2060,15 @@
int pcre_fullinfo(const pcre *code, const pcre_extra *extra,
int what, void *where);
- The pcre_fullinfo() function returns information about a compiled pat-
- tern. It replaces the pcre_info() function, which was removed from the
+ The pcre_fullinfo() function returns information about a compiled pat-
+ tern. It replaces the pcre_info() function, which was removed from the
library at version 8.30, after more than 10 years of obsolescence.
- The first argument for pcre_fullinfo() is a pointer to the compiled
- pattern. The second argument is the result of pcre_study(), or NULL if
- the pattern was not studied. The third argument specifies which piece
- of information is required, and the fourth argument is a pointer to a
- variable to receive the data. The yield of the function is zero for
+ The first argument for pcre_fullinfo() is a pointer to the compiled
+ pattern. The second argument is the result of pcre_study(), or NULL if
+ the pattern was not studied. The third argument specifies which piece
+ of information is required, and the fourth argument is a pointer to a
+ variable to receive the data. The yield of the function is zero for
success, or one of the following negative numbers:
PCRE_ERROR_NULL the argument code was NULL
@@ -2073,10 +2078,10 @@
endianness
PCRE_ERROR_BADOPTION the value of what was invalid
- The "magic number" is placed at the start of each compiled pattern as
- an simple check against passing an arbitrary memory pointer. The endi-
+ The "magic number" is placed at the start of each compiled pattern as
+ an simple check against passing an arbitrary memory pointer. The endi-
anness error can occur if a compiled pattern is saved and reloaded on a
- different host. Here is a typical call of pcre_fullinfo(), to obtain
+ different host. Here is a typical call of pcre_fullinfo(), to obtain
the length of the compiled pattern:
int rc;
@@ -2087,154 +2092,154 @@
PCRE_INFO_SIZE, /* what is required */
&length); /* where to put the data */
- The possible values for the third argument are defined in pcre.h, and
+ The possible values for the third argument are defined in pcre.h, and
are as follows:
PCRE_INFO_BACKREFMAX
- Return the number of the highest back reference in the pattern. The
- fourth argument should point to an int variable. Zero is returned if
+ Return the number of the highest back reference in the pattern. The
+ fourth argument should point to an int variable. Zero is returned if
there are no back references.
PCRE_INFO_CAPTURECOUNT
- Return the number of capturing subpatterns in the pattern. The fourth
+ Return the number of capturing subpatterns in the pattern. The fourth
argument should point to an int variable.
PCRE_INFO_DEFAULT_TABLES
- Return a pointer to the internal default character tables within PCRE.
- The fourth argument should point to an unsigned char * variable. This
+ Return a pointer to the internal default character tables within PCRE.
+ The fourth argument should point to an unsigned char * variable. This
information call is provided for internal use by the pcre_study() func-
- tion. External callers can cause PCRE to use its internal tables by
+ tion. External callers can cause PCRE to use its internal tables by
passing a NULL table pointer.
PCRE_INFO_FIRSTBYTE
Return information about the first data unit of any matched string, for
- a non-anchored pattern. (The name of this option refers to the 8-bit
- library, where data units are bytes.) The fourth argument should point
+ a non-anchored pattern. (The name of this option refers to the 8-bit
+ library, where data units are bytes.) The fourth argument should point
to an int variable.
- If there is a fixed first value, for example, the letter "c" from a
- pattern such as (cat|cow|coyote), its value is returned. In the 8-bit
- library, the value is always less than 256; in the 16-bit library the
+ If there is a fixed first value, for example, the letter "c" from a
+ pattern such as (cat|cow|coyote), its value is returned. In the 8-bit
+ library, the value is always less than 256; in the 16-bit library the
value can be up to 0xffff.
If there is no fixed first value, and if either
- (a) the pattern was compiled with the PCRE_MULTILINE option, and every
+ (a) the pattern was compiled with the PCRE_MULTILINE option, and every
branch starts with "^", or
(b) every branch of the pattern starts with ".*" and PCRE_DOTALL is not
set (if it were set, the pattern would be anchored),
- -1 is returned, indicating that the pattern matches only at the start
- of a subject string or after any newline within the string. Otherwise
+ -1 is returned, indicating that the pattern matches only at the start
+ of a subject string or after any newline within the string. Otherwise
-2 is returned. For anchored patterns, -2 is returned.
PCRE_INFO_FIRSTTABLE
- If the pattern was studied, and this resulted in the construction of a
- 256-bit table indicating a fixed set of values for the first data unit
- in any matching string, a pointer to the table is returned. Otherwise
- NULL is returned. The fourth argument should point to an unsigned char
+ If the pattern was studied, and this resulted in the construction of a
+ 256-bit table indicating a fixed set of values for the first data unit
+ in any matching string, a pointer to the table is returned. Otherwise
+ NULL is returned. The fourth argument should point to an unsigned char
* variable.
PCRE_INFO_HASCRORLF
- Return 1 if the pattern contains any explicit matches for CR or LF
- characters, otherwise 0. The fourth argument should point to an int
- variable. An explicit match is either a literal CR or LF character, or
+ Return 1 if the pattern contains any explicit matches for CR or LF
+ characters, otherwise 0. The fourth argument should point to an int
+ variable. An explicit match is either a literal CR or LF character, or
\r or \n.
PCRE_INFO_JCHANGED
- Return 1 if the (?J) or (?-J) option setting is used in the pattern,
- otherwise 0. The fourth argument should point to an int variable. (?J)
+ Return 1 if the (?J) or (?-J) option setting is used in the pattern,
+ otherwise 0. The fourth argument should point to an int variable. (?J)
and (?-J) set and unset the local PCRE_DUPNAMES option, respectively.
PCRE_INFO_JIT
- Return 1 if the pattern was studied with the PCRE_STUDY_JIT_COMPILE
- option, and just-in-time compiling was successful. The fourth argument
- should point to an int variable. A return value of 0 means that JIT
- support is not available in this version of PCRE, or that the pattern
- was not studied with the PCRE_STUDY_JIT_COMPILE option, or that the JIT
- compiler could not handle this particular pattern. See the pcrejit doc-
- umentation for details of what can and cannot be handled.
+ Return 1 if the pattern was studied with one of the JIT options, and
+ just-in-time compiling was successful. The fourth argument should point
+ to an int variable. A return value of 0 means that JIT support is not
+ available in this version of PCRE, or that the pattern was not studied
+ with a JIT option, or that the JIT compiler could not handle this par-
+ ticular pattern. See the pcrejit documentation for details of what can
+ and cannot be handled.
PCRE_INFO_JITSIZE
- If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE
- option, return the size of the JIT compiled code, otherwise return
- zero. The fourth argument should point to a size_t variable.
+ If the pattern was successfully studied with a JIT option, return the
+ size of the JIT compiled code, otherwise return zero. The fourth argu-
+ ment should point to a size_t variable.
PCRE_INFO_LASTLITERAL
- Return the value of the rightmost literal data unit that must exist in
- any matched string, other than at its start, if such a value has been
+ Return the value of the rightmost literal data unit that must exist in
+ any matched string, other than at its start, if such a value has been
recorded. The fourth argument should point to an int variable. If there
is no such value, -1 is returned. For anchored patterns, a last literal
- value is recorded only if it follows something of variable length. For
+ value is recorded only if it follows something of variable length. For
example, for the pattern /^a\d+z\d+/ the returned value is "z", but for
/^a\dz\d/ the returned value is -1.
PCRE_INFO_MINLENGTH
- If the pattern was studied and a minimum length for matching subject
- strings was computed, its value is returned. Otherwise the returned
- value is -1. The value is a number of characters, which in UTF-8 mode
- may be different from the number of bytes. The fourth argument should
- point to an int variable. A non-negative 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
+ If the pattern was studied and a minimum length for matching subject
+ strings was computed, its value is returned. Otherwise the returned
+ value is -1. The value is a number of characters, which in UTF-8 mode
+ may be different from the number of bytes. The fourth argument should
+ point to an int variable. A non-negative 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.
PCRE_INFO_NAMECOUNT
PCRE_INFO_NAMEENTRYSIZE
PCRE_INFO_NAMETABLE
- PCRE supports the use of named as well as numbered capturing parenthe-
- ses. The names are just an additional way of identifying the parenthe-
+ PCRE supports the use of named as well as numbered capturing parenthe-
+ ses. The names are just an additional way of identifying the parenthe-
ses, which still acquire numbers. Several convenience functions such as
- pcre_get_named_substring() 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
+ pcre_get_named_substring() 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 pcre_exec() below). To do
- the conversion, you need to use the name-to-number map, which is
+ 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. PCRE_INFO_NAMECOUNT
gives the number of entries, and PCRE_INFO_NAMEENTRYSIZE gives the size
- of each entry; both of these return an int value. The entry size
- depends on the length of the longest name. PCRE_INFO_NAMETABLE returns
+ of each entry; both of these return an int value. The entry size
+ depends on the length of the longest name. PCRE_INFO_NAMETABLE returns
a pointer to the first entry of the table. This is a pointer to char in
the 8-bit library, where the first two bytes of each entry are the num-
- ber of the capturing parenthesis, most significant byte first. In the
- 16-bit library, the pointer points to 16-bit data units, the first of
- which contains the parenthesis number. The rest of the entry is the
+ ber of the capturing parenthesis, most significant byte first. In the
+ 16-bit library, the pointer points to 16-bit data 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. Duplicate names may appear if (?|
+ The names are in alphabetical order. Duplicate names may appear if (?|
is used to create multiple groups with the same number, as described in
- the section on duplicate subpattern numbers in the pcrepattern page.
- Duplicate names for subpatterns with different numbers are permitted
- only if PCRE_DUPNAMES is set. In all cases of duplicate names, they
- appear in the table in the order in which they were found in the pat-
- tern. In the absence of (?| this is the order of increasing number;
+ the section on duplicate subpattern numbers in the pcrepattern page.
+ Duplicate names for subpatterns with different numbers are permitted
+ only if PCRE_DUPNAMES is set. In all cases of duplicate names, they
+ appear in the table in the order in which they were found in the pat-
+ tern. In the absence of (?| this is the order of increasing number;
when (?| is used this is not necessarily the case because later subpat-
terns may have lower numbers.
- As a simple example of the name/number table, consider the following
+ As a simple example of the name/number table, consider the following
pattern after compilation by the 8-bit library (assume PCRE_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 ??:
@@ -2243,31 +2248,31 @@
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.
PCRE_INFO_OKPARTIAL
- Return 1 if the pattern can be used for partial matching with
- pcre_exec(), otherwise 0. The fourth argument should point to an int
- variable. From release 8.00, this always returns 1, because the
- restrictions that previously applied to partial matching have been
- lifted. The pcrepartial documentation gives details of partial match-
+ Return 1 if the pattern can be used for partial matching with
+ pcre_exec(), otherwise 0. The fourth argument should point to an int
+ variable. From release 8.00, this always returns 1, because the
+ restrictions that previously applied to partial matching have been
+ lifted. The pcrepartial documentation gives details of partial match-
ing.
PCRE_INFO_OPTIONS
- Return a copy of the options with which the pattern was compiled. The
- fourth argument should point to an unsigned long int variable. These
+ Return a copy of the options with which the pattern was compiled. The
+ fourth argument should point to an unsigned long int variable. These
option bits are those specified in the call to pcre_compile(), modified
by any top-level option settings at the start of the pattern itself. In
- other words, they are the options that will be in force when matching
- starts. For example, if the pattern /(?im)abc(?-i)d/ is compiled with
- the PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
+ other words, they are the options that will be in force when matching
+ starts. For example, if the pattern /(?im)abc(?-i)d/ is compiled with
+ the PCRE_EXTENDED option, the result is PCRE_CASELESS, PCRE_MULTILINE,
and PCRE_EXTENDED.
- A pattern is automatically anchored by PCRE if all of its top-level
+ A pattern is automatically anchored by PCRE if all of its top-level
alternatives begin with one of the following:
^ unless PCRE_MULTILINE is set
@@ -2281,24 +2286,24 @@
PCRE_INFO_SIZE
- Return the size of the compiled pattern in bytes (for both libraries).
- The fourth argument should point to a size_t variable. This value does
- not include the size of the pcre structure that is returned by
- pcre_compile(). The value that is passed as the argument to pcre_mal-
- loc() when pcre_compile() is getting memory in which to place the com-
- piled data is the value returned by this option plus the size of the
- pcre structure. Studying a compiled pattern, with or without JIT, does
+ Return the size of the compiled pattern in bytes (for both libraries).
+ The fourth argument should point to a size_t variable. This value does
+ not include the size of the pcre structure that is returned by
+ pcre_compile(). The value that is passed as the argument to pcre_mal-
+ loc() when pcre_compile() is getting memory in which to place the com-
+ piled data is the value returned by this option plus the size of the
+ pcre structure. Studying a compiled pattern, with or without JIT, does
not alter the value returned by this option.
PCRE_INFO_STUDYSIZE
Return the size in bytes of the data block pointed to by the study_data
- field in a pcre_extra block. If pcre_extra is NULL, or there is no
- study data, zero is returned. The fourth argument should point to a
- size_t variable. The study_data field is set by pcre_study() to record
- information that will speed up matching (see the section entitled
+ field in a pcre_extra block. If pcre_extra is NULL, or there is no
+ study data, zero is returned. The fourth argument should point to a
+ size_t variable. The study_data field is set by pcre_study() to record
+ information that will speed up matching (see the section entitled
"Studying a pattern" above). The format of the study_data block is pri-
- vate, but its length is made available via this option so that it can
+ vate, but its length is made available via this option so that it can
be saved and restored (see the pcreprecompile documentation for
details).
@@ -2307,21 +2312,21 @@
int pcre_refcount(pcre *code, int adjust);
- The pcre_refcount() function is used to maintain a reference count in
+ The pcre_refcount() function is used to maintain a reference count in
the data block that contains a compiled pattern. It is provided for the
- benefit of applications that operate in an object-oriented manner,
+ benefit of applications that operate in an object-oriented manner,
where different parts of the application may be using the same compiled
pattern, but you want to free the block when they are all done.
When a pattern is compiled, the reference count field is initialized to
- zero. It is changed only by calling this function, whose action is to
- add the adjust value (which may be positive or negative) to it. The
+ zero. It is changed only by calling this function, whose action is to
+ add the adjust value (which may be positive or negative) to it. The
yield of the function is the new value. However, the value of the count
- is constrained to lie between 0 and 65535, inclusive. If the new value
+ is constrained to lie between 0 and 65535, inclusive. If the new value
is outside these limits, it is forced to the appropriate limit value.
- Except when it is zero, the reference count is not correctly preserved
- if a pattern is compiled on one host and then transferred to a host
+ Except when it is zero, the reference count is not correctly preserved
+ if a pattern is compiled on one host and then transferred to a host
whose byte-order is different. (This seems a highly unlikely scenario.)
@@ -2331,22 +2336,22 @@
const char *subject, int length, int startoffset,
int options, int *ovector, int ovecsize);
- The function pcre_exec() is called to match a subject string against a
- compiled pattern, which is passed in the code argument. If the pattern
- was studied, the result of the study should be passed in the extra
- argument. You can call pcre_exec() with the same code and extra argu-
- ments as many times as you like, in order to match different subject
+ The function pcre_exec() is called to match a subject string against a
+ compiled pattern, which is passed in the code argument. If the pattern
+ was studied, the result of the study should be passed in the extra
+ argument. You can call pcre_exec() with the same code and extra argu-
+ ments as many times as you like, in order to match different 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 pcre_dfa_exec() function.
- In most applications, the pattern will have been compiled (and option-
- ally studied) in the same process that calls pcre_exec(). However, it
+ In most applications, the pattern will have been compiled (and option-
+ ally studied) in the same process that calls pcre_exec(). However, it
is possible to save compiled patterns and study data, and then use them
- later in different processes, possibly even on different hosts. For a
+ later in different processes, possibly even on different hosts. For a
discussion about this, see the pcreprecompile documentation.
Here is an example of a simple call to pcre_exec():
@@ -2365,10 +2370,10 @@
Extra data for pcre_exec()
- If the extra argument is not NULL, it must point to a pcre_extra data
- block. The pcre_study() function returns such a block (when it doesn't
- return NULL), but you can also create one for yourself, and pass addi-
- tional information in it. The pcre_extra block contains the following
+ If the extra argument is not NULL, it must point to a pcre_extra data
+ block. The pcre_study() function returns such a block (when it doesn't
+ return NULL), but you can also create one for yourself, and pass addi-
+ tional information in it. The pcre_extra block contains the following
fields (not necessarily in this order):
unsigned long int flags;
@@ -2380,126 +2385,126 @@
const unsigned char *tables;
unsigned char **mark;
- In the 16-bit version of this structure, the mark field has type
+ In the 16-bit version of this structure, the mark field has type
"PCRE_UCHAR16 **".
- The flags field is a bitmap that specifies which of the other fields
- are set. The flag bits are:
+ The flags field is used to specify which of the other fields are set.
+ The flag bits are:
- PCRE_EXTRA_STUDY_DATA
+ PCRE_EXTRA_CALLOUT_DATA
PCRE_EXTRA_EXECUTABLE_JIT
+ PCRE_EXTRA_MARK
PCRE_EXTRA_MATCH_LIMIT
PCRE_EXTRA_MATCH_LIMIT_RECURSION
- PCRE_EXTRA_CALLOUT_DATA
+ PCRE_EXTRA_STUDY_DATA
PCRE_EXTRA_TABLES
- PCRE_EXTRA_MARK
- Other flag bits should be set to zero. The study_data field and some-
- times the executable_jit field are set in the pcre_extra block that is
- returned by pcre_study(), together with the appropriate flag bits. You
- should not set these yourself, but you may add to the block by setting
- the other fields and their corresponding flag bits.
+ Other flag bits should be set to zero. The study_data field and some-
+ times the executable_jit field are set in the pcre_extra block that is
+ returned by pcre_study(), together with the appropriate flag bits. You
+ should not set these yourself, but you may add to the block by setting
+ other fields and their corresponding flag bits.
The match_limit field provides a means of preventing PCRE from using up
- a vast amount of resources when running 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 nested unlim-
+ a vast amount of resources when running 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 nested unlim-
ited repeats.
- Internally, pcre_exec() uses a function called match(), which it calls
- repeatedly (sometimes recursively). The limit set by match_limit is
- imposed on the number of times this function is called during a match,
- which has the effect of limiting the amount of backtracking that can
+ Internally, pcre_exec() uses a function called match(), which it calls
+ repeatedly (sometimes recursively). The limit set by match_limit is
+ imposed on the number of times this function is called during a match,
+ which 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.
When pcre_exec() is called with a pattern that was successfully studied
- with the PCRE_STUDY_JIT_COMPILE option, the way that the 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 long the matching can continue.
+ with a JIT option, the way that the 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 long the match-
+ ing can continue.
- The default value for the limit can be set when PCRE is built; the
- default default is 10 million, which handles all but the most extreme
- cases. You can override the default by suppling pcre_exec() with a
- pcre_extra block in which match_limit is set, and
- PCRE_EXTRA_MATCH_LIMIT is set in the flags field. If the limit is
+ The default value for the limit can be set when PCRE is built; the
+ default default is 10 million, which handles all but the most extreme
+ cases. You can override the default by suppling pcre_exec() with a
+ pcre_extra block in which match_limit is set, and
+ PCRE_EXTRA_MATCH_LIMIT is set in the flags field. If the limit is
exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
- The match_limit_recursion field is similar to match_limit, but instead
+ The match_limit_recursion field is similar to match_limit, but instead
of limiting the total number of times that match() is called, it limits
- the depth of recursion. The recursion depth is a smaller number than
- the total number of calls, because not all calls to match() are recur-
+ the depth of recursion. The recursion depth is a smaller number than
+ the total number of calls, because not all calls to match() are recur-
sive. This limit is of use only if it is set smaller than match_limit.
- Limiting the recursion depth limits the amount of machine stack that
- can be used, or, when PCRE has been compiled to use memory on the heap
- instead of the stack, the amount of heap memory that can be used. This
- limit is not relevant, and is ignored, if the pattern was successfully
- studied with PCRE_STUDY_JIT_COMPILE.
+ Limiting the recursion depth limits the amount of machine stack that
+ can be used, or, when PCRE has been compiled to use memory on the heap
+ instead of the stack, the amount of heap memory that can be used. This
+ limit is not relevant, and is ignored, when matching is done using JIT
+ compiled code.
- The default value for match_limit_recursion can be set when PCRE is
- built; the default default is the same value as the default for
- match_limit. You can override the default by suppling pcre_exec() with
- a pcre_extra block in which match_limit_recursion is set, and
- PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the flags field. If the
+ The default value for match_limit_recursion can be set when PCRE is
+ built; the default default is the same value as the default for
+ match_limit. You can override the default by suppling pcre_exec() with
+ a pcre_extra block in which match_limit_recursion is set, and
+ PCRE_EXTRA_MATCH_LIMIT_RECURSION is set in the flags field. If the
limit is exceeded, pcre_exec() returns PCRE_ERROR_RECURSIONLIMIT.
- The callout_data field is used in conjunction with the "callout" fea-
+ The callout_data field is used in conjunction with the "callout" fea-
ture, and is described in the pcrecallout documentation.
- The tables field is used to pass a character tables pointer to
- pcre_exec(); this overrides the value that is stored with the compiled
- pattern. A non-NULL value is stored with the compiled pattern only if
- custom tables were supplied to pcre_compile() via its tableptr argu-
+ The tables field is used to pass a character tables pointer to
+ pcre_exec(); this overrides the value that is stored with the compiled
+ pattern. A non-NULL value is stored with the compiled pattern only if
+ custom tables were supplied to pcre_compile() via its tableptr argu-
ment. If NULL is passed to pcre_exec() using this mechanism, it forces
- PCRE's internal tables to be used. This facility is helpful when re-
- using patterns that have been saved after compiling with an external
- set of tables, because the external tables might be at a different
- address when pcre_exec() is called. See the pcreprecompile documenta-
+ PCRE's internal tables to be used. This facility is helpful when re-
+ using patterns that have been saved after compiling with an external
+ set of tables, because the external tables might be at a different
+ address when pcre_exec() is called. See the pcreprecompile documenta-
tion for a discussion of saving compiled patterns for later use.
- If PCRE_EXTRA_MARK is set in the flags field, the mark field must be
- set to point to a suitable variable. If the pattern contains any back-
- tracking control verbs such as (*MARK:NAME), and the execution ends up
- with a name to pass back, a pointer to the name string (zero termi-
- nated) is placed in the variable pointed to by the mark field. The
- names are within the compiled pattern; if you wish to retain such a
- name you must copy it before freeing the memory of a compiled pattern.
- If there is no name to pass back, the variable pointed to by the mark
- field is set to NULL. For details of the backtracking control verbs,
+ If PCRE_EXTRA_MARK is set in the flags field, the mark field must be
+ set to point to a suitable variable. If the pattern contains any back-
+ tracking control verbs such as (*MARK:NAME), and the execution ends up
+ with a name to pass back, a pointer to the name string (zero termi-
+ nated) is placed in the variable pointed to by the mark field. The
+ names are within the compiled pattern; if you wish to retain such a
+ name you must copy it before freeing the memory of a compiled pattern.
+ If there is no name to pass back, the variable pointed to by the mark
+ field is set to NULL. For details of the backtracking control verbs,
see the section entitled "Backtracking control" in the pcrepattern doc-
umentation.
Option bits for pcre_exec()
- The unused bits of the options argument for pcre_exec() must be zero.
- The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
- PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
- PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_SOFT, and
- PCRE_PARTIAL_HARD.
+ The unused bits of the options argument for pcre_exec() must be zero.
+ The only bits that may be set are PCRE_ANCHORED, PCRE_NEWLINE_xxx,
+ PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART,
+ PCRE_NO_START_OPTIMIZE, PCRE_NO_UTF8_CHECK, PCRE_PARTIAL_HARD, and
+ PCRE_PARTIAL_SOFT.
- If the pattern was successfully studied with the PCRE_STUDY_JIT_COMPILE
- option, the only supported options for JIT execution are
- PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and
- PCRE_NOTEMPTY_ATSTART. Note in particular that partial matching is not
- supported. If an unsupported option is used, JIT execution is disabled
- and the normal interpretive code in pcre_exec() is run.
+ If the pattern was successfully studied with one of the just-in-time
+ (JIT) compile options, the only supported options for JIT execution are
+ PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
+ PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT. If an
+ unsupported option is used, JIT execution is disabled and the normal
+ interpretive code in pcre_exec() is run.
PCRE_ANCHORED
- The PCRE_ANCHORED option limits pcre_exec() to matching at the first
- matching position. If a pattern was compiled with PCRE_ANCHORED, or
- turned out to be anchored by virtue of its contents, it cannot be made
+ The PCRE_ANCHORED option limits pcre_exec() to matching at the first
+ matching position. If a pattern was compiled with PCRE_ANCHORED, or
+ turned out to be anchored by virtue of its contents, it cannot be made
unachored at matching time.
PCRE_BSR_ANYCRLF
PCRE_BSR_UNICODE
These options (which are mutually exclusive) control what the \R escape
- sequence matches. The choice is either to match only CR, LF, or CRLF,
- or to match any Unicode newline sequence. These options override the
+ sequence matches. The choice is either to match only CR, LF, or CRLF,
+ or to match any Unicode newline sequence. These options override the
choice that was made or defaulted when the pattern was compiled.
PCRE_NEWLINE_CR
@@ -2508,334 +2513,336 @@
PCRE_NEWLINE_ANYCRLF
PCRE_NEWLINE_ANY
- These options override the newline definition that was chosen or
- defaulted when the pattern was compiled. For details, see the descrip-
- tion of pcre_compile() above. During matching, the newline choice
- affects the behaviour of the dot, circumflex, and dollar metacharac-
- ters. It may also alter the way the match position is advanced after a
+ These options override the newline definition that was chosen or
+ defaulted when the pattern was compiled. For details, see the descrip-
+ tion of pcre_compile() above. During matching, the newline choice
+ affects the behaviour of the dot, circumflex, and dollar metacharac-
+ ters. It may also alter the way the match position is advanced after a
match failure for an unanchored pattern.
- When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is
- set, and a match attempt for an unanchored pattern fails when the cur-
- rent position is at a CRLF sequence, and the pattern contains no
- explicit matches for CR or LF characters, the match position is
+ When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is
+ set, and a match attempt for an unanchored pattern fails when the cur-
+ rent 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 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 PCRE_DOTALL
+ expected. For example, if the pattern is .+A (and the PCRE_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, or one of the \r or \n escape sequences. Implicit
- matches such as [^X] do not count, nor does \s (which includes CR and
+ those characters, or one of the \r or \n escape sequences. Implicit
+ matches such as [^X] do not count, nor does \s (which includes CR and
LF in the characters 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.
PCRE_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 PCRE_MULTILINE (at compile time)
- causes circumflex never to match. This option affects only the behav-
+ the beginning of a line, so the circumflex metacharacter should not
+ match before it. Setting this without PCRE_MULTILINE (at compile time)
+ causes circumflex never to match. This option affects only the behav-
iour of the circumflex metacharacter. It does not affect \A.
PCRE_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-
+ 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 PCRE_MULTILINE (at compile time) causes dollar never to match. This
- option affects only the behaviour of the dollar metacharacter. It does
+ option affects only the behaviour of the dollar metacharacter. It does
not affect \Z or \z.
PCRE_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
- empty string at the start of the subject. With PCRE_NOTEMPTY set, this
+ is applied to a string not beginning with "a" or "b", it matches an
+ empty string at the start of the subject. With PCRE_NOTEMPTY set, this
match is not valid, so PCRE searches further into the string for occur-
rences of "a" or "b".
PCRE_NOTEMPTY_ATSTART
- This is like PCRE_NOTEMPTY, except that an empty string match that is
- not at the start of the subject is permitted. If the pattern is
+ This is like PCRE_NOTEMPTY, except that an empty string match that is
+ not at the start of the subject is permitted. If the pattern is
anchored, such a match can occur only if the pattern contains \K.
- Perl has no direct equivalent of PCRE_NOTEMPTY or
- PCRE_NOTEMPTY_ATSTART, but it does make a special case of a pattern
- match of the empty string within its split() function, and when using
- the /g modifier. It is possible to emulate Perl's behaviour after
+ Perl has no direct equivalent of PCRE_NOTEMPTY or
+ PCRE_NOTEMPTY_ATSTART, but it does make a special case of a pattern
+ match of the empty string within its split() function, and when using
+ the /g modifier. It is possible to emulate Perl's behaviour after
matching a null string by first trying the match again at the same off-
- set with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then if that
+ set with PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED, and then if that
fails, by advancing the starting offset (see below) and trying an ordi-
- nary match again. There is some code that demonstrates how to do this
- in the pcredemo 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
+ nary match again. There is some code that demonstrates how to do this
+ in the pcredemo 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
starting offset by two characters instead of one.
PCRE_NO_START_OPTIMIZE
- There are a number of optimizations that pcre_exec() uses at the start
- of a match, in order to speed up the process. For example, if it is
+ There are a number of optimizations that pcre_exec() uses 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 character, it
- searches the subject for that character, and fails immediately if it
- cannot find it, without actually running the main matching function.
+ searches the subject for that character, and fails immediately if it
+ cannot find it, without actually running the main matching function.
This means that a special item such as (*COMMIT) at the start of a pat-
- tern is not considered until after a suitable starting point for the
- match has been found. When callouts or (*MARK) items are in use, these
+ tern is not considered until after a suitable starting point for the
+ match has been found. 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 optimizations are in effect a pre-
+ never actually used. The start-up optimizations are in effect a pre-
scan of the subject that takes place before the pattern is run.
- The PCRE_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
+ The PCRE_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
such as (*COMMIT) and (*MARK) are considered at every possible starting
- position in the subject string. If PCRE_NO_START_OPTIMIZE is set at
- compile time, it cannot be unset at matching time.
+ position in the subject string. If PCRE_NO_START_OPTIMIZE is set at
+ compile time, it cannot be unset at matching time. The use of
+ PCRE_NO_START_OPTIMIZE disables JIT execution; when it is set, matching
+ is always done using interpretively.
- Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching
+ Setting PCRE_NO_START_OPTIMIZE can change the outcome of a matching
operation. Consider the pattern
(*COMMIT)ABC
- When this is compiled, PCRE 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 PCRE_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". If the pattern is studied, more start-up opti-
- mizations may be used. For example, a minimum length for the subject
+ When this is compiled, PCRE 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 PCRE_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". If the pattern is studied, more start-up opti-
+ mizations may be used. 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
- "ABC", there will be attempts to match "ABC", "BC", "C", and then
- finally an empty string. If the pattern is studied, the final attempt
- does not take place, because PCRE knows that the subject is too short,
- and so the (*MARK) is never encountered. In this case, studying the
- pattern does not affect the overall match result, which is still "no
+ The minimum length for a match is one character. If the subject is
+ "ABC", there will be attempts to match "ABC", "BC", "C", and then
+ finally an empty string. If the pattern is studied, the final attempt
+ does not take place, because PCRE knows that the subject is too short,
+ and so the (*MARK) is never encountered. In this case, studying the
+ pattern does not affect the overall match result, which is still "no
match", but it does affect the auxiliary information that is returned.
PCRE_NO_UTF8_CHECK
When PCRE_UTF8 is set at compile time, the validity of the subject as a
- UTF-8 string is automatically checked when pcre_exec() is subsequently
- called. The value of startoffset is also checked to ensure that it
- points to the start of a UTF-8 character. There is a discussion about
- the validity of UTF-8 strings in the pcreunicode page. If an invalid
- sequence of bytes is found, pcre_exec() returns the error
+ UTF-8 string is automatically checked when pcre_exec() is subsequently
+ called. The value of startoffset is also checked to ensure that it
+ points to the start of a UTF-8 character. There is a discussion about
+ the validity of UTF-8 strings in the pcreunicode page. If an invalid
+ sequence of bytes is found, pcre_exec() returns the error
PCRE_ERROR_BADUTF8 or, if PCRE_PARTIAL_HARD is set and the problem is a
truncated character at the end of the subject, PCRE_ERROR_SHORTUTF8. In
- both cases, information about the precise nature of the error may also
- be returned (see the descriptions of these errors in the section enti-
- tled Error return values from pcre_exec() below). If startoffset con-
+ both cases, information about the precise nature of the error may also
+ be returned (see the descriptions of these errors in the section enti-
+ tled Error return values from pcre_exec() below). If startoffset con-
tains a value that does not point to the start of a UTF-8 character (or
to the end of the subject), PCRE_ERROR_BADUTF8_OFFSET is returned.
- If you already know that your subject is valid, and you want to skip
- these checks for performance reasons, you can set the
- PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might want to
- do this for the second and subsequent calls to pcre_exec() if you are
- making repeated calls to find all the matches in a single subject
- string. However, you should be sure that the value of startoffset
- points to the start of a character (or the end of the subject). When
+ If you already know that your subject is valid, and you want to skip
+ these checks for performance reasons, you can set the
+ PCRE_NO_UTF8_CHECK option when calling pcre_exec(). You might want to
+ do this for the second and subsequent calls to pcre_exec() if you are
+ making repeated calls to find all the matches in a single subject
+ string. However, you should be sure that the value of startoffset
+ points to the start of a character (or the end of the subject). When
PCRE_NO_UTF8_CHECK is set, the effect of passing an invalid string as a
- subject or an invalid value of startoffset is undefined. Your program
+ subject or an invalid value of startoffset is undefined. Your program
may crash.
PCRE_PARTIAL_HARD
PCRE_PARTIAL_SOFT
- These options turn on the partial matching feature. For backwards com-
- patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. 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
+ These options turn on the partial matching feature. For backwards com-
+ patibility, PCRE_PARTIAL is a synonym for PCRE_PARTIAL_SOFT. 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 PCRE_PARTIAL_SOFT (but not PCRE_PARTIAL_HARD) is set,
- matching continues by testing any remaining alternatives. Only if no
- complete match can be found is PCRE_ERROR_PARTIAL returned instead of
- PCRE_ERROR_NOMATCH. In other words, PCRE_PARTIAL_SOFT says that the
- caller is prepared to handle a partial match, but only if no complete
+ matching continues by testing any remaining alternatives. Only if no
+ complete match can be found is PCRE_ERROR_PARTIAL returned instead of
+ PCRE_ERROR_NOMATCH. In other words, PCRE_PARTIAL_SOFT says that the
+ caller is prepared to handle a partial match, but only if no complete
match can be found.
- If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this
- case, if a partial match is found, pcre_exec() immediately returns
- PCRE_ERROR_PARTIAL, without considering any other alternatives. In
- other words, when PCRE_PARTIAL_HARD is set, a partial match is consid-
+ If PCRE_PARTIAL_HARD is set, it overrides PCRE_PARTIAL_SOFT. In this
+ case, if a partial match is found, pcre_exec() immediately returns
+ PCRE_ERROR_PARTIAL, without considering any other alternatives. In
+ other words, when PCRE_PARTIAL_HARD is set, a partial match is consid-
ered to be more important that an alternative complete match.
- In both cases, the portion of the string that was inspected when the
+ In both cases, the portion of the string that was inspected when the
partial match was found is set as the first matching string. 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 pcrepartial documentation.
The string to be matched by pcre_exec()
- The subject string is passed to pcre_exec() as a pointer in subject, a
- length in bytes in length, and a starting byte offset in startoffset.
- If this is negative or greater than the length of the subject,
- pcre_exec() returns PCRE_ERROR_BADOFFSET. When the starting offset is
- zero, the search for a match starts at the beginning of the subject,
+ The subject string is passed to pcre_exec() as a pointer in subject, a
+ length in bytes in length, and a starting byte offset in startoffset.
+ If this is negative or greater than the length of the subject,
+ pcre_exec() returns PCRE_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 mode, the byte offset
- must point to the start of a UTF-8 character (or the end of the sub-
- ject). Unlike the pattern string, the subject may contain binary zero
+ must point to the start of a UTF-8 character (or the end of the sub-
+ ject). Unlike the pattern string, the subject may contain binary zero
bytes.
- A non-zero starting offset is useful when searching for another match
- in the same subject by calling pcre_exec() again after a previous suc-
- cess. Setting startoffset differs from just passing over a shortened
- string and setting PCRE_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 pcre_exec() again after a previous suc-
+ cess. Setting startoffset differs from just passing over a shortened
+ string and setting PCRE_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.)
- When applied to the string "Mississipi" the first call to pcre_exec()
- finds the first occurrence. If pcre_exec() is called again with just
- the remainder of the subject, namely "issipi", it does not match,
+ 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 pcre_exec()
+ finds the first occurrence. If pcre_exec() 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 pcre_exec() is passed the entire
+ to be a word boundary. However, if pcre_exec() 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
- PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED options, and then if that
- fails, advancing the starting offset and trying an ordinary match
+ first trying the match again at the same offset, with the
+ PCRE_NOTEMPTY_ATSTART and PCRE_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 pcre-
demo 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
+ if the newline convention recognizes CRLF as a newline, and if so, and
the current character is CR followed by LF, advance the starting offset
by two characters instead of one.
- If a non-zero starting offset is passed when the pattern is anchored,
+ If a non-zero starting offset is passed when the pattern is anchored,
one attempt to match at the given offset is made. This can only succeed
- if the pattern does not require the match to be at the start of the
+ if the pattern does not require the match to be at the start of the
subject.
How pcre_exec() returns captured substrings
- In general, a pattern matches a certain portion of the subject, and in
- addition, further substrings from the subject may be picked out by
- parts of the pattern. Following the usage in Jeffrey Friedl's book,
- this is called "capturing" in what follows, and the phrase "capturing
- subpattern" is used for a fragment of a pattern that picks out a sub-
- string. PCRE supports several other kinds of parenthesized subpattern
+ In general, a pattern matches a certain portion of the subject, and in
+ addition, further substrings from the subject may be picked out by
+ parts of the pattern. Following the usage in Jeffrey Friedl's book,
+ this is called "capturing" in what follows, and the phrase "capturing
+ subpattern" is used for a fragment of a pattern that picks out a sub-
+ string. PCRE supports several other kinds of parenthesized subpattern
that do not cause substrings to be captured.
Captured substrings are returned to the caller via a vector of integers
- whose address is passed in ovector. The number of elements in the vec-
- tor is passed in ovecsize, which must be a non-negative number. Note:
+ whose address is passed in ovector. The number of elements in the vec-
+ tor is passed in ovecsize, which must be a non-negative number. Note:
this argument is NOT the size of ovector in bytes.
- The first two-thirds of the vector is used to pass back captured sub-
- strings, each substring using a pair of integers. The remaining third
- of the vector is used as workspace by pcre_exec() while matching cap-
- turing subpatterns, and is not available for passing back information.
- The number passed in ovecsize should always be a multiple of three. If
+ The first two-thirds of the vector is used to pass back captured sub-
+ strings, each substring using a pair of integers. The remaining third
+ of the vector is used as workspace by pcre_exec() while matching cap-
+ turing subpatterns, and is not available for passing back information.
+ The number passed in ovecsize should always be a multiple of three. If
it is not, it is rounded down.
- When a match is successful, information about captured substrings is
- returned in pairs of integers, starting at the beginning of ovector,
- and continuing up to two-thirds of its length at the most. The first
- element of each pair is set to the byte offset of the first character
- in a substring, and the second is set to the byte offset of the first
- character after the end of a substring. Note: these values are always
+ When a match is successful, information about captured substrings is
+ returned in pairs of integers, starting at the beginning of ovector,
+ and continuing up to two-thirds of its length at the most. The first
+ element of each pair is set to the byte offset of the first character
+ in a substring, and the second is set to the byte offset of the first
+ character after the end of a substring. Note: these values are always
byte offsets, even in UTF-8 mode. They are not character counts.
- The first pair of integers, ovector[0] and ovector[1], identify the
- portion of the subject string matched by the entire pattern. The next
- pair is used for the first capturing subpattern, and so on. The value
+ The first pair of integers, ovector[0] and ovector[1], identify the
+ portion of the subject string matched by the entire pattern. The next
+ pair is used for the first capturing subpattern, and so on. The value
returned by pcre_exec() 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 capturing subpatterns, the return
+ has been set. For example, if two substrings have been captured, the
+ returned value is 3. If there are no capturing subpatterns, the return
value from a successful match is 1, indicating that just the first pair
of offsets has been set.
If a capturing subpattern is matched repeatedly, it is the last portion
of the string that it matched that is returned.
- If the vector is too small to hold all the captured substring offsets,
+ If the vector is too small to hold all the captured substring offsets,
it is used as far as possible (up to two-thirds of its length), and the
- function returns a value of zero. If neither the actual string matched
- not any captured substrings are of interest, pcre_exec() may be called
- with ovector passed as NULL and ovecsize as zero. However, if the pat-
- tern contains back references and the ovector is not big enough to
- remember the related substrings, PCRE has to get additional memory for
- use during matching. Thus it is usually advisable to supply an ovector
+ function returns a value of zero. If neither the actual string matched
+ not any captured substrings are of interest, pcre_exec() may be called
+ with ovector passed as NULL and ovecsize as zero. However, if the pat-
+ tern contains back references and the ovector is not big enough to
+ remember the related substrings, PCRE has to get additional memory for
+ use during matching. Thus it is usually advisable to supply an ovector
of reasonable size.
- There are some cases where zero is returned (indicating vector over-
- flow) when in fact the vector is exactly the right size for the final
+ There are some cases where zero is returned (indicating vector over-
+ flow) when in fact the vector is exactly the right size for the final
match. For example, consider the pattern
(a)(?:(b)c|bd)
- If a vector of 6 elements (allowing for only 1 captured substring) is
+ If a vector of 6 elements (allowing for only 1 captured substring) is
given with subject string "abd", pcre_exec() will try to set the second
captured string, thereby recording a vector overflow, before failing to
- match "c" and backing up to try the second alternative. The zero
- return, however, does correctly indicate that the maximum number of
+ match "c" and backing up to try the second alternative. The zero
+ return, however, does correctly indicate that the maximum number of
slots (namely 2) have been filled. In similar cases where there is tem-
- porary overflow, but the final number of used slots is actually less
+ porary overflow, but the final number of used slots is actually less
than the maximum, a non-zero value is returned.
The pcre_fullinfo() function can be used to find out how many capturing
- subpatterns there are in a compiled pattern. The smallest size for
- ovector that will allow for n captured substrings, in addition to the
+ subpatterns there are in a compiled pattern. The smallest size for
+ ovector that will allow for n captured substrings, in addition to the
offsets of the substring matched by the whole pattern, is (n+1)*3.
- 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 -1.
- Offset values that correspond to unused subpatterns at the end of the
- expression are also set to -1. 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 highest used
- capturing subpattern number is 1, and the offsets for for the second
- and third capturing subpatterns (assuming the vector is large enough,
+ Offset values that correspond to unused subpatterns at the end of the
+ expression are also set to -1. 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 highest used
+ capturing subpattern number is 1, and the offsets for for the second
+ and third capturing subpatterns (assuming the vector is large enough,
of course) are set to -1.
- Note: Elements in the first two-thirds of ovector that do not corre-
- spond to capturing parentheses in the pattern are never changed. That
- is, if a pattern contains n capturing parentheses, no more than ovec-
- tor[0] to ovector[2n+1] are set by pcre_exec(). The other elements (in
+ Note: Elements in the first two-thirds of ovector that do not corre-
+ spond to capturing parentheses in the pattern are never changed. That
+ is, if a pattern contains n capturing parentheses, no more than ovec-
+ tor[0] to ovector[2n+1] are set by pcre_exec(). The other elements (in
the first two-thirds) retain whatever values they previously had.
- Some convenience functions are provided for extracting the captured
+ Some convenience functions are provided for extracting the captured
substrings as separate strings. These are described below.
Error return values from pcre_exec()
- If pcre_exec() fails, it returns a negative number. The following are
+ If pcre_exec() fails, it returns a negative number. The following are
defined in the header file:
PCRE_ERROR_NOMATCH (-1)
@@ -2844,7 +2851,7 @@
PCRE_ERROR_NULL (-2)
- Either code or subject was passed as NULL, or ovector was NULL and
+ Either code or subject was passed as NULL, or ovector was NULL and
ovecsize was not zero.
PCRE_ERROR_BADOPTION (-3)
@@ -2853,82 +2860,82 @@
PCRE_ERROR_BADMAGIC (-4)
- PCRE stores a 4-byte "magic number" at the start of the compiled code,
+ PCRE stores a 4-byte "magic number" at the start of the compiled code,
to catch the case when it is passed a junk pointer and to detect when a
pattern that was compiled in an environment of one endianness is run in
- an environment with the other endianness. This is the error that PCRE
+ an environment with the other endianness. This is the error that PCRE
gives when the magic number is not present.
PCRE_ERROR_UNKNOWN_OPCODE (-5)
While running the pattern match, an unknown item was encountered in the
- compiled pattern. This error could be caused by a bug in PCRE or by
+ compiled pattern. This error could be caused by a bug in PCRE or by
overwriting of the compiled pattern.
PCRE_ERROR_NOMEMORY (-6)
- If a pattern contains back references, but the ovector that is passed
+ If a pattern contains back references, but the ovector that is passed
to pcre_exec() is not big enough to remember the referenced substrings,
- PCRE gets a block of memory at the start of matching to use for this
- purpose. If the call via pcre_malloc() fails, this error is given. The
+ PCRE gets a block of memory at the start of matching to use for this
+ purpose. If the call via pcre_malloc() fails, this error is given. The
memory is automatically freed at the end of matching.
- This error is also given if pcre_stack_malloc() fails in pcre_exec().
- This can happen only when PCRE has been compiled with --disable-stack-
+ This error is also given if pcre_stack_malloc() fails in pcre_exec().
+ This can happen only when PCRE has been compiled with --disable-stack-
for-recursion.
PCRE_ERROR_NOSUBSTRING (-7)
- This error is used by the pcre_copy_substring(), pcre_get_substring(),
+ This error is used by the pcre_copy_substring(), pcre_get_substring(),
and pcre_get_substring_list() functions (see below). It is never
returned by pcre_exec().
PCRE_ERROR_MATCHLIMIT (-8)
- The backtracking limit, as specified by the match_limit field in a
- pcre_extra structure (or defaulted) was reached. See the description
+ The backtracking limit, as specified by the match_limit field in a
+ pcre_extra structure (or defaulted) was reached. See the description
above.
PCRE_ERROR_CALLOUT (-9)
This error is never generated by pcre_exec() itself. It is provided for
- use by callout functions that want to yield a distinctive error code.
+ use by callout functions that want to yield a distinctive error code.
See the pcrecallout documentation for details.
PCRE_ERROR_BADUTF8 (-10)
- A string that contains an invalid UTF-8 byte sequence was passed as a
- subject, and the PCRE_NO_UTF8_CHECK option was not set. If the size of
- the output vector (ovecsize) is at least 2, the byte offset to the
- start of the the invalid UTF-8 character is placed in the first ele-
- ment, and a reason code is placed in the second element. The reason
+ A string that contains an invalid UTF-8 byte sequence was passed as a
+ subject, and the PCRE_NO_UTF8_CHECK option was not set. If the size of
+ the output vector (ovecsize) is at least 2, the byte offset to the
+ start of the the invalid UTF-8 character is placed in the first ele-
+ ment, and a reason code is placed in the second element. The reason
codes are listed in the following section. For backward compatibility,
- if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char-
- acter at the end of the subject (reason codes 1 to 5),
+ if PCRE_PARTIAL_HARD is set and the problem is a truncated UTF-8 char-
+ acter at the end of the subject (reason codes 1 to 5),
PCRE_ERROR_SHORTUTF8 is returned instead of PCRE_ERROR_BADUTF8.
PCRE_ERROR_BADUTF8_OFFSET (-11)
- The UTF-8 byte sequence that was passed as a subject was checked and
- found to be valid (the PCRE_NO_UTF8_CHECK option was not set), but the
- value of startoffset did not point to the beginning of a UTF-8 charac-
+ The UTF-8 byte sequence that was passed as a subject was checked and
+ found to be valid (the PCRE_NO_UTF8_CHECK option was not set), but the
+ value of startoffset did not point to the beginning of a UTF-8 charac-
ter or the end of the subject.
PCRE_ERROR_PARTIAL (-12)
- 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
pcrepartial documentation for details of partial matching.
PCRE_ERROR_BADPARTIAL (-13)
- This code is no longer in use. It was formerly returned when the
- PCRE_PARTIAL option was used with a compiled pattern containing items
- that were not supported for partial matching. From release 8.00
+ This code is no longer in use. It was formerly returned when the
+ PCRE_PARTIAL option was used with a compiled pattern containing items
+ that were not supported for partial matching. From release 8.00
onwards, there are no restrictions on partial matching.
PCRE_ERROR_INTERNAL (-14)
- 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 PCRE or by overwriting of the compiled pattern.
PCRE_ERROR_BADCOUNT (-15)
@@ -2938,7 +2945,7 @@
PCRE_ERROR_RECURSIONLIMIT (-21)
The internal recursion limit, as specified by the match_limit_recursion
- field in a pcre_extra structure (or defaulted) was reached. See the
+ field in a pcre_extra structure (or defaulted) was reached. See the
description above.
PCRE_ERROR_BADNEWLINE (-23)
@@ -2952,30 +2959,30 @@
PCRE_ERROR_SHORTUTF8 (-25)
- This error is returned instead of PCRE_ERROR_BADUTF8 when the subject
- string ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD
- option is set. Information about the failure is returned as for
- PCRE_ERROR_BADUTF8. It is in fact sufficient to detect this case, but
- this special error code for PCRE_PARTIAL_HARD precedes the implementa-
- tion of returned information; it is retained for backwards compatibil-
+ This error is returned instead of PCRE_ERROR_BADUTF8 when the subject
+ string ends with a truncated UTF-8 character and the PCRE_PARTIAL_HARD
+ option is set. Information about the failure is returned as for
+ PCRE_ERROR_BADUTF8. It is in fact sufficient to detect this case, but
+ this special error code for PCRE_PARTIAL_HARD precedes the implementa-
+ tion of returned information; it is retained for backwards compatibil-
ity.
PCRE_ERROR_RECURSELOOP (-26)
This error is returned when pcre_exec() detects a recursion loop within
- the pattern. Specifically, it means that either the whole pattern or a
- subpattern has been called recursively for the second time at the same
+ the pattern. Specifically, it means that either the whole pattern 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 complicated cases,
+ are detected and faulted at compile time, but more complicated cases,
in particular mutual recursions between two different subpatterns, can-
not be detected until run time.
PCRE_ERROR_JIT_STACKLIMIT (-27)
- This error is returned when a pattern that was successfully studied
- using the PCRE_STUDY_JIT_COMPILE option is being matched, but the mem-
- ory available for the just-in-time processing stack is not large
- enough. See the pcrejit documentation for more details.
+ This error is returned when a pattern that was successfully studied
+ using a JIT compile option is being matched, but the memory available
+ for the just-in-time processing stack is not large enough. See the
+ pcrejit documentation for more details.
PCRE_ERROR_BADMODE (-28)
@@ -2984,8 +2991,8 @@
PCRE_ERROR_BADENDIANNESS (-29)
- This error is given if a pattern that was compiled and saved is
- reloaded on a host with different endianness. The utility function
+ This error is given if a pattern that was compiled and saved is
+ reloaded on a host with different endianness. The utility function
pcre_pattern_to_host_byte_order() can be used to convert such a pattern
so that it runs on the new host.
@@ -2993,14 +3000,14 @@
Reason codes for invalid UTF-8 strings
- This section applies only to the 8-bit library. The corresponding
+ This section applies only to the 8-bit library. The corresponding
information for the 16-bit library is given in the pcre16 page.
When pcre_exec() returns either PCRE_ERROR_BADUTF8 or PCRE_ERROR_SHORT-
- UTF8, and the size of the output vector (ovecsize) is at least 2, the
- offset of the start of the invalid UTF-8 character is placed in the
+ UTF8, and the size of the output vector (ovecsize) is at least 2, the
+ offset of the start of the invalid UTF-8 character is placed in the
first output vector element (ovector[0]) and a reason code is placed in
- the second element (ovector[1]). The reason codes are given names in
+ the second element (ovector[1]). The reason codes are given names in
the pcre.h header file:
PCRE_UTF8_ERR1
@@ -3009,10 +3016,10 @@
PCRE_UTF8_ERR4
PCRE_UTF8_ERR5
- The string ends with a truncated UTF-8 character; the code specifies
- how many bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8
- characters to be no longer than 4 bytes, the encoding scheme (origi-
- nally defined by RFC 2279) allows for up to 6 bytes, and this is
+ The string ends with a truncated UTF-8 character; the code specifies
+ how many bytes are missing (1 to 5). Although RFC 3629 restricts UTF-8
+ characters to be no longer than 4 bytes, the encoding scheme (origi-
+ nally defined by RFC 2279) allows for up to 6 bytes, and this is
checked first; hence the possibility of 4 or 5 missing bytes.
PCRE_UTF8_ERR6
@@ -3022,24 +3029,24 @@
PCRE_UTF8_ERR10
The two most significant bits of the 2nd, 3rd, 4th, 5th, or 6th byte of
- the character do not have the binary value 0b10 (that is, either the
+ the character do not have the binary value 0b10 (that is, either the
most significant bit is 0, or the next bit is 1).
PCRE_UTF8_ERR11
PCRE_UTF8_ERR12
- A character that is valid by the RFC 2279 rules is either 5 or 6 bytes
+ A character that is valid by the RFC 2279 rules is either 5 or 6 bytes
long; these code points are excluded by RFC 3629.
PCRE_UTF8_ERR13
- A 4-byte character has a value greater than 0x10fff; these code points
+ A 4-byte character has a value greater than 0x10fff; these code points
are excluded by RFC 3629.
PCRE_UTF8_ERR14
- A 3-byte character has a value in the range 0xd800 to 0xdfff; this
- range of code points are reserved by RFC 3629 for use with UTF-16, and
+ A 3-byte character has a value in the range 0xd800 to 0xdfff; this
+ range of code points are reserved by RFC 3629 for use with UTF-16, and
so are excluded from UTF-8.
PCRE_UTF8_ERR15
@@ -3048,21 +3055,21 @@
PCRE_UTF8_ERR18
PCRE_UTF8_ERR19
- A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes
- for a value that can be represented by fewer bytes, which is invalid.
- For example, the two bytes 0xc0, 0xae give the value 0x2e, whose cor-
+ A 2-, 3-, 4-, 5-, or 6-byte character is "overlong", that is, it codes
+ for a value that can be represented by fewer bytes, which is invalid.
+ For example, the two bytes 0xc0, 0xae give the value 0x2e, whose cor-
rect coding uses just one byte.
PCRE_UTF8_ERR20
The two most significant bits of the first byte of a character have the
- binary value 0b10 (that is, the most significant bit is 1 and the sec-
- ond is 0). Such a byte can only validly occur as the second or subse-
+ binary value 0b10 (that is, the most significant bit is 1 and the sec-
+ ond is 0). Such a byte can only validly occur as the second or subse-
quent byte of a multi-byte character.
PCRE_UTF8_ERR21
- The first byte of a character has the value 0xfe or 0xff. These values
+ The first byte of a character has the value 0xfe or 0xff. These values
can never occur in a valid UTF-8 string.
@@ -3079,78 +3086,78 @@
int pcre_get_substring_list(const char *subject,
int *ovector, int stringcount, const char ***listptr);
- Captured substrings can be accessed directly by using the offsets
- returned by pcre_exec() in ovector. For convenience, the functions
+ Captured substrings can be accessed directly by using the offsets
+ returned by pcre_exec() in ovector. For convenience, the functions
pcre_copy_substring(), pcre_get_substring(), and pcre_get_sub-
- string_list() are provided for extracting captured substrings as new,
- separate, zero-terminated strings. These functions identify substrings
- by number. The next section describes functions for extracting named
+ string_list() are provided for extracting captured substrings as new,
+ separate, zero-terminated strings. These functions identify substrings
+ by number. The next section describes functions for extracting named
substrings.
- 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 course, a C
- string. However, you can process such a string by referring to the
- length that is returned by pcre_copy_substring() and pcre_get_sub-
+ 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 course, a C
+ string. However, you can process such a string by referring to the
+ length that is returned by pcre_copy_substring() and pcre_get_sub-
string(). Unfortunately, the interface to pcre_get_substring_list() is
- not adequate for handling strings containing binary zeros, because the
+ not adequate for handling strings containing binary zeros, because the
end of the final string is not independently indicated.
- The first three arguments are the same for all three of these func-
- tions: subject is the subject string that has just been successfully
+ The first three arguments are the same for all three of these func-
+ tions: subject is the subject string that has just been successfully
matched, ovector is a pointer to the vector of integer offsets that was
passed to pcre_exec(), and stringcount is the number of substrings that
- were captured by the match, including the substring that matched the
+ were captured by the match, including the substring that matched the
entire regular expression. This is the value returned by pcre_exec() if
- it is greater than zero. If pcre_exec() returned zero, indicating that
- it ran out of space in ovector, the value passed as stringcount should
+ it is greater than zero. If pcre_exec() returned zero, indicating that
+ it ran out of space in ovector, the value passed as stringcount should
be the number of elements in the vector divided by three.
- The functions pcre_copy_substring() and pcre_get_substring() extract a
- single substring, whose number is given as stringnumber. A value of
- zero extracts the substring that matched the entire pattern, whereas
- higher values extract the captured substrings. For pcre_copy_sub-
- string(), the string is placed in buffer, whose length is given by
- buffersize, while for pcre_get_substring() a new block of memory is
- obtained via pcre_malloc, and its address is returned via stringptr.
- The yield of the function is the length of the string, not including
+ The functions pcre_copy_substring() and pcre_get_substring() extract a
+ single substring, whose number is given as stringnumber. A value of
+ zero extracts the substring that matched the entire pattern, whereas
+ higher values extract the captured substrings. For pcre_copy_sub-
+ string(), the string is placed in buffer, whose length is given by
+ buffersize, while for pcre_get_substring() a new block of memory is
+ obtained via pcre_malloc, and its address is returned via stringptr.
+ The yield of the function is the length of the string, not including
the terminating zero, or one of these error codes:
PCRE_ERROR_NOMEMORY (-6)
- The buffer was too small for pcre_copy_substring(), or the attempt to
+ The buffer was too small for pcre_copy_substring(), or the attempt to
get memory failed for pcre_get_substring().
PCRE_ERROR_NOSUBSTRING (-7)
There is no substring whose number is stringnumber.
- The pcre_get_substring_list() function extracts all available sub-
- strings and builds a list of pointers to them. All this is done in a
+ The pcre_get_substring_list() function extracts all available sub-
+ strings and builds a list of pointers to them. All this is done in a
single block of memory that is obtained via pcre_malloc. 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 yield of the function is zero if all went well, or the
+ 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 yield of the function is zero if all went well, or the
error code
PCRE_ERROR_NOMEMORY (-6)
if the attempt to get the memory block failed.
- When any of these functions encounter 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, they return an
+ When any of these functions encounter 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, they return an
empty string. This can be distinguished from a genuine zero-length sub-
- string by inspecting the appropriate offset in ovector, which is nega-
+ string by inspecting the appropriate offset in ovector, which is nega-
tive for unset substrings.
- The two convenience functions pcre_free_substring() and pcre_free_sub-
- string_list() can be used to free the memory returned by a previous
+ The two convenience functions pcre_free_substring() and pcre_free_sub-
+ string_list() can be used to free the memory returned by a previous
call of pcre_get_substring() or pcre_get_substring_list(), respec-
- tively. They do nothing more than call the function pointed to by
- pcre_free, which of course could be called directly from a C program.
- However, PCRE is used in some situations where it is linked via a spe-
- cial interface to another programming language that cannot use
- pcre_free directly; it is for these cases that the functions are pro-
+ tively. They do nothing more than call the function pointed to by
+ pcre_free, which of course could be called directly from a C program.
+ However, PCRE is used in some situations where it is linked via a spe-
+ cial interface to another programming language that cannot use
+ pcre_free directly; it is for these cases that the functions are pro-
vided.
@@ -3169,7 +3176,7 @@
int stringcount, const char *stringname,
const char **stringptr);
- 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+)...
@@ -3178,35 +3185,35 @@
be unique (PCRE_DUPNAMES was not set), you can find the number from the
name by calling pcre_get_stringnumber(). The first argument is the com-
piled pattern, and the second is the name. The yield of the function is
- the subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no
+ the subpattern number, or PCRE_ERROR_NOSUBSTRING (-7) if there is no
subpattern of that name.
Given the number, you can extract the substring directly, or use one of
the functions described in the previous section. For convenience, there
are also two functions that do the whole job.
- Most of the arguments of pcre_copy_named_substring() and
- pcre_get_named_substring() are the same as those for the similarly
- named functions that extract by number. As these are described in the
- previous section, they are not re-described here. There are just two
+ Most of the arguments of pcre_copy_named_substring() and
+ pcre_get_named_substring() are the same as those for the similarly
+ named functions that extract by number. As these are described in the
+ previous section, they are not re-described here. There are just two
differences:
- First, instead of a substring number, a substring name is given. Sec-
+ First, instead of a substring number, a substring name is given. Sec-
ond, there is an extra argument, given at the start, which is a pointer
- to the compiled pattern. This is needed in order to gain access to the
+ to the compiled pattern. This is needed in order to gain access to the
name-to-number translation table.
- These functions call pcre_get_stringnumber(), and if it succeeds, they
- then call pcre_copy_substring() or pcre_get_substring(), as appropri-
- ate. NOTE: If PCRE_DUPNAMES is set and there are duplicate names, the
+ These functions call pcre_get_stringnumber(), and if it succeeds, they
+ then call pcre_copy_substring() or pcre_get_substring(), as appropri-
+ ate. NOTE: If PCRE_DUPNAMES is set and there are duplicate names, the
behaviour may not be what you want (see the next section).
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 pcrepattern 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 pcrepattern 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.
@@ -3215,76 +3222,76 @@
int pcre_get_stringtable_entries(const pcre *code,
const char *name, char **first, char **last);
- When a pattern is compiled with the PCRE_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 PCRE_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 pcrepattern documentation.
- When duplicates are present, pcre_copy_named_substring() and
- pcre_get_named_substring() return the first substring corresponding to
- the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING
- (-7) is returned; no data is returned. The pcre_get_stringnumber()
- function returns one of the numbers that are associated with the name,
+ When duplicates are present, pcre_copy_named_substring() and
+ pcre_get_named_substring() return the first substring corresponding to
+ the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING
+ (-7) is returned; no data is returned. The pcre_get_stringnumber()
+ function returns one of the numbers that are associated with the name,
but it is not defined which it is.
- If you want to get full details of all captured substrings for a given
- name, you must use the pcre_get_stringtable_entries() function. The
+ If you want to get full details of all captured substrings for a given
+ name, you must use the pcre_get_stringtable_entries() function. The
first argument is the compiled pattern, and the second is the name. The
- third and fourth are pointers to variables which are updated by the
+ third and fourth are pointers to variables which 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. The function itself
- returns the length of each entry, or PCRE_ERROR_NOSUBSTRING (-7) if
- there are none. The format of the table is described above in the sec-
- tion entitled Information about a pattern above. Given all the rele-
- vant entries for the name, you can extract each of their numbers, and
+ the name-to-number table for the given name. The function itself
+ returns the length of each entry, or PCRE_ERROR_NOSUBSTRING (-7) if
+ there are none. The format of the table is described above in the sec-
+ tion entitled Information about a pattern above. Given all the rele-
+ vant entries for the name, you can extract each of their numbers, and
hence the captured data, if any.
FINDING ALL POSSIBLE MATCHES
- The traditional matching function uses a similar algorithm to Perl,
+ The traditional matching function uses a similar algorithm to Perl,
which stops when it finds the first match, starting at a given point in
- the subject. If you want to find all possible matches, or the longest
- possible match, consider using the alternative matching function (see
- below) instead. If you cannot use the alternative function, but still
- need to find all possible matches, you can kludge it up by making use
+ the subject. If you want to find all possible matches, or the longest
+ possible match, consider using the alternative matching function (see
+ below) instead. If you cannot use the alternative function, but still
+ need to find all possible matches, you can kludge it up by making use
of the callout facility, which is described in the pcrecallout documen-
tation.
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 pcre_exec() 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 pcre_exec() to
+ backtrack and try other alternatives. Ultimately, when it runs out of
matches, pcre_exec() will yield PCRE_ERROR_NOMATCH.
OBTAINING AN ESTIMATE OF STACK USAGE
- Matching certain patterns using pcre_exec() can use a lot of process
- stack, which in certain environments can be rather limited in size.
- Some users find it helpful to have an estimate of the amount of stack
- that is used by pcre_exec(), to help them set recursion limits, as
- described in the pcrestack documentation. The estimate that is output
+ Matching certain patterns using pcre_exec() can use a lot of process
+ stack, which in certain environments can be rather limited in size.
+ Some users find it helpful to have an estimate of the amount of stack
+ that is used by pcre_exec(), to help them set recursion limits, as
+ described in the pcrestack documentation. The estimate that is output
by pcretest when called with the -m and -C options is obtained by call-
- ing pcre_exec with the values NULL, NULL, NULL, -999, and -999 for its
+ ing pcre_exec with the values NULL, NULL, NULL, -999, and -999 for its
first five arguments.
- Normally, if its first argument is NULL, pcre_exec() immediately
- returns the negative error code PCRE_ERROR_NULL, but with this special
- combination of arguments, it returns instead a negative number whose
- absolute value is the approximate stack frame size in bytes. (A nega-
- tive number is used so that it is clear that no match has happened.)
- The value is approximate because in some cases, recursive calls to
+ Normally, if its first argument is NULL, pcre_exec() immediately
+ returns the negative error code PCRE_ERROR_NULL, but with this special
+ combination of arguments, it returns instead a negative number whose
+ absolute value is the approximate stack frame size in bytes. (A nega-
+ tive number is used so that it is clear that no match has happened.)
+ The value is approximate because in some cases, recursive calls to
pcre_exec() occur when there are one or two additional variables on the
stack.
- If PCRE has been compiled to use the heap instead of the stack for
- recursion, the value returned is the size of each block that is
+ If PCRE has been compiled to use the heap instead of the stack for
+ recursion, the value returned is the size of each block that is
obtained from the heap.
@@ -3295,26 +3302,26 @@
int options, int *ovector, int ovecsize,
int *workspace, int wscount);
- The function pcre_dfa_exec() is called to match a subject string
- against a compiled pattern, using a matching algorithm that scans the
- subject string just once, and does not backtrack. This has different
- characteristics to the normal algorithm, and is not compatible with
- Perl. Some of the features of PCRE patterns are not supported. Never-
- theless, 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 pcre_dfa_exec() does not support, see the pcrematching documenta-
+ The function pcre_dfa_exec() is called to match a subject string
+ against a compiled pattern, using a matching algorithm that scans the
+ subject string just once, and does not backtrack. This has different
+ characteristics to the normal algorithm, and is not compatible with
+ Perl. Some of the features of PCRE patterns are not supported. Never-
+ theless, 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 pcre_dfa_exec() does not support, see the pcrematching documenta-
tion.
- The arguments for the pcre_dfa_exec() function are the same as for
+ The arguments for the pcre_dfa_exec() function are the same as for
pcre_exec(), plus two extras. The ovector argument is used in a differ-
- ent way, and this is described below. The other common arguments are
- used in the same way as for pcre_exec(), so their description is not
+ ent way, and this is described below. The other common arguments are
+ used in the same way as for pcre_exec(), 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 will be needed for patterns and subjects where there are a
+ workspace will be needed for patterns and subjects where there are a
lot of potential matches.
Here is an example of a simple call to pcre_dfa_exec():
@@ -3336,55 +3343,55 @@
Option bits for pcre_dfa_exec()
- The unused bits of the options argument for pcre_dfa_exec() must be
- zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEW-
+ The unused bits of the options argument for pcre_dfa_exec() must be
+ zero. The only bits that may be set are PCRE_ANCHORED, PCRE_NEW-
LINE_xxx, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
- PCRE_NOTEMPTY_ATSTART, PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF,
- PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE, PCRE_PARTIAL_HARD, PCRE_PAR-
- TIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last
- four of these are exactly the same as for pcre_exec(), so their
+ PCRE_NOTEMPTY_ATSTART, PCRE_NO_UTF8_CHECK, PCRE_BSR_ANYCRLF,
+ PCRE_BSR_UNICODE, PCRE_NO_START_OPTIMIZE, PCRE_PARTIAL_HARD, PCRE_PAR-
+ TIAL_SOFT, PCRE_DFA_SHORTEST, and PCRE_DFA_RESTART. All but the last
+ four of these are exactly the same as for pcre_exec(), so their
description is not repeated here.
PCRE_PARTIAL_HARD
PCRE_PARTIAL_SOFT
- These have the same general effect as they do for pcre_exec(), but the
- details are slightly different. When PCRE_PARTIAL_HARD is set for
- pcre_dfa_exec(), it returns PCRE_ERROR_PARTIAL if the end of the sub-
- ject is reached and there is still at least one matching possibility
+ These have the same general effect as they do for pcre_exec(), but the
+ details are slightly different. When PCRE_PARTIAL_HARD is set for
+ pcre_dfa_exec(), it returns PCRE_ERROR_PARTIAL if the end of the sub-
+ ject is reached and there is still at least one matching possibility
that requires additional characters. This happens even if some complete
matches have also been found. When PCRE_PARTIAL_SOFT is set, the return
code PCRE_ERROR_NOMATCH is converted into PCRE_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 portion 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 exam-
+ of the subject is reached, there have been no complete matches, but
+ there is still at least one matching possibility. The portion 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 exam-
ples, in the pcrepartial documentation.
PCRE_DFA_SHORTEST
- Setting the PCRE_DFA_SHORTEST option causes the matching algorithm to
+ Setting the PCRE_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.
PCRE_DFA_RESTART
When pcre_dfa_exec() returns a partial match, it is possible to call it
- again, with additional subject characters, and have it continue with
- the same match. The PCRE_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
+ again, with additional subject characters, and have it continue with
+ the same match. The PCRE_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
after a partial match. There is more discussion of this facility in the
pcrepartial documentation.
Successful returns from pcre_dfa_exec()
- When pcre_dfa_exec() succeeds, it may have matched more than one sub-
+ When pcre_dfa_exec() 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
<.*>
@@ -3399,63 +3406,63 @@
<something> <something else>
<something> <something else> <something further>
- On success, the yield of the function is a number greater than zero,
- which is the number of matched substrings. The substrings themselves
- are returned in ovector. Each string uses two elements; the first is
- the offset to the start, and the second is the offset to the end. In
- fact, all the strings have the same start offset. (Space could have
- been saved by giving this only once, but it was decided to retain some
- compatibility with the way pcre_exec() returns data, even though the
+ On success, the yield of the function is a number greater than zero,
+ which is the number of matched substrings. The substrings themselves
+ are returned in ovector. Each string uses two elements; the first is
+ the offset to the start, and the second is the offset to the end. In
+ fact, all the strings have the same start offset. (Space could have
+ been saved by giving this only once, but it was decided to retain some
+ compatibility with the way pcre_exec() returns data, even though the
meaning of the strings is different.)
The strings are returned in reverse order of length; that is, the long-
- est matching string is given first. If there were too many matches to
- fit into ovector, the yield of the function is zero, and the vector is
- filled with the longest matches. Unlike pcre_exec(), pcre_dfa_exec()
+ est matching string is given first. If there were too many matches to
+ fit into ovector, the yield of the function is zero, and the vector is
+ filled with the longest matches. Unlike pcre_exec(), pcre_dfa_exec()
can use the entire ovector for returning matched strings.
Error returns from pcre_dfa_exec()
- The pcre_dfa_exec() function returns a negative number when it fails.
- Many of the errors are the same as for pcre_exec(), and these are
- described above. There are in addition the following errors that are
+ The pcre_dfa_exec() function returns a negative number when it fails.
+ Many of the errors are the same as for pcre_exec(), and these are
+ described above. There are in addition the following errors that are
specific to pcre_dfa_exec():
PCRE_ERROR_DFA_UITEM (-16)
- This return is given if pcre_dfa_exec() encounters an item in the pat-
- tern that it does not support, for instance, the use of \C or a back
+ This return is given if pcre_dfa_exec() encounters an item in the pat-
+ tern that it does not support, for instance, the use of \C or a back
reference.
PCRE_ERROR_DFA_UCOND (-17)
- This return is given if pcre_dfa_exec() encounters a condition item
- that uses a back reference for the condition, or a test for recursion
+ This return is given if pcre_dfa_exec() encounters a condition item
+ that uses a back reference for the condition, or a test for recursion
in a specific group. These are not supported.
PCRE_ERROR_DFA_UMLIMIT (-18)
- This return is given if pcre_dfa_exec() is called with an extra block
- that contains a setting of the match_limit or match_limit_recursion
- fields. This is not supported (these fields are meaningless for DFA
+ This return is given if pcre_dfa_exec() is called with an extra block
+ that contains a setting of the match_limit or match_limit_recursion
+ fields. This is not supported (these fields are meaningless for DFA
matching).
PCRE_ERROR_DFA_WSSIZE (-19)
- This return is given if pcre_dfa_exec() runs out of space in the
+ This return is given if pcre_dfa_exec() runs out of space in the
workspace vector.
PCRE_ERROR_DFA_RECURSE (-20)
- When a recursive subpattern is processed, the matching function calls
- itself recursively, using private vectors for ovector and workspace.
- This error is given if the output vector is not large enough. This
+ When a recursive subpattern is processed, the matching function calls
+ itself recursively, using private vectors for ovector and workspace.
+ This error is given if the output vector is not large enough. This
should be extremely rare, as a vector of size 1000 is used.
SEE ALSO
- pcre16(3), pcrebuild(3), pcrecallout(3), pcrecpp(3)(3), pcrematch-
+ pcre16(3), pcrebuild(3), pcrecallout(3), pcrecpp(3)(3), pcrematch-
ing(3), pcrepartial(3), pcreposix(3), pcreprecompile(3), pcresample(3),
pcrestack(3).
@@ -3469,11 +3476,11 @@
REVISION
- Last updated: 21 January 2012
+ Last updated: 22 February 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCRECALLOUT(3) PCRECALLOUT(3)
@@ -3671,8 +3678,8 @@
Last updated: 08 Janurary 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCRECOMPAT(3) PCRECOMPAT(3)
@@ -3846,8 +3853,8 @@
Last updated: 08 Januray 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREPATTERN(3) PCREPATTERN(3)
@@ -6181,6 +6188,8 @@
follows the colon, the effect is as if the colon were not there. Any
number of these verbs may occur in a pattern.
+ Optimizations that affect backtracking verbs
+
PCRE contains some optimizations that are used to speed up matching by
running some checks at the start of each match attempt. For example, it
may know the minimum length of matching subject, or that a particular
@@ -6189,6 +6198,8 @@
course, be processed. You can suppress the start-of-match optimizations
by setting the PCRE_NO_START_OPTIMIZE option when calling pcre_com-
pile() or pcre_exec(), or by starting the pattern with (*NO_START_OPT).
+ There is more discussion of this option in the section entitled "Option
+ bits for pcre_exec()" in the pcreapi documentation.
Experiments with Perl suggest that it too has similar optimizations,
sometimes leading to anomalous results.
@@ -6268,10 +6279,14 @@
No match, mark = B
Note that in this unanchored example the mark is retained from the
- match attempt that started at the letter "X". Subsequent match attempts
- starting at "P" and then with an empty string do not get as far as the
- (*MARK) item, but nevertheless do not reset it.
+ match attempt that started at the letter "X" in the subject. Subsequent
+ match attempts starting at "P" and then with an empty string do not get
+ as far as the (*MARK) item, but nevertheless do not reset it.
+ If you are interested in (*MARK) values after failed matches, you
+ should probably set the PCRE_NO_START_OPTIMIZE option (see above) to
+ ensure that the match is always attempted.
+
Verbs that act after backtracking
The following verbs do nothing when they are encountered. Matching con-
@@ -6448,11 +6463,11 @@
REVISION
- Last updated: 09 January 2012
+ Last updated: 24 February 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCRESYNTAX(3) PCRESYNTAX(3)
@@ -6827,8 +6842,8 @@
Last updated: 10 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREUNICODE(3) PCREUNICODE(3)
@@ -7025,8 +7040,8 @@
Last updated: 13 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREJIT(3) PCREJIT(3)
@@ -7072,15 +7087,13 @@
MIPS 32-bit
Power PC 32-bit and 64-bit
- The Power PC support is designated as experimental because it has not
- been fully tested. If --enable-jit is set on an unsupported platform,
- compilation fails.
+ If --enable-jit is set on an unsupported platform, compilation fails.
A program that is linked with PCRE 8.20 or later can tell if JIT sup-
port is available by calling pcre_config() with the PCRE_CONFIG_JIT
option. The result is 1 when JIT is available, and 0 otherwise. How-
ever, a simple program does not need to check this in order to use JIT.
- The API is implemented in a way that falls back to the ordinary PCRE
+ The API is implemented in a way that falls back to the interpretive
code if JIT is not available.
If your program may sometimes be linked with versions of PCRE that are
@@ -7099,7 +7112,7 @@
pcre_exec().
(2) Use pcre_free_study() to free the pcre_extra block when it is
- no longer needed instead of just freeing it yourself. This
+ no longer needed, instead of just freeing it yourself. This
ensures that any JIT data is also freed.
For a program that may be linked with pre-8.20 versions of PCRE, you
@@ -7118,30 +7131,51 @@
pcre_free(study_ptr);
#endif
- In some circumstances you may need to call additional functions. These
- are described in the section entitled "Controlling the JIT stack"
+ PCRE_STUDY_JIT_COMPILE requests the JIT compiler to generate code for
+ complete matches. If you want to run partial matches using the
+ PCRE_PARTIAL_HARD or PCRE_PARTIAL_SOFT options of pcre_exec(), you
+ should set one or both of the following options in addition to, or
+ instead of, PCRE_STUDY_JIT_COMPILE when you call pcre_study():
+
+ PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+
+ The JIT compiler generates different optimized code for each of the
+ three modes (normal, soft partial, hard partial). When pcre_exec() is
+ called, the appropriate code is run if it is available. Otherwise, the
+ pattern is matched using interpretive code.
+
+ In some circumstances you may need to call additional functions. These
+ are described in the section entitled "Controlling the JIT stack"
below.
- If JIT support is not available, PCRE_STUDY_JIT_COMPILE is ignored, and
- no JIT data is set up. Otherwise, the compiled pattern is passed to the
- JIT compiler, which turns it into machine code that executes much
- faster than the normal interpretive code. When pcre_exec() is passed a
- pcre_extra block containing a pointer to JIT code, it obeys that
- instead of the normal code. The result is identical, but the code runs
- much faster.
+ If JIT support is not available, PCRE_STUDY_JIT_COMPILE etc. are
+ ignored, and no JIT data is created. Otherwise, the compiled pattern is
+ passed to the JIT compiler, which turns it into machine code that exe-
+ cutes much faster than the normal interpretive code. When pcre_exec()
+ is passed a pcre_extra block containing a pointer to JIT code of the
+ appropriate mode (normal or hard/soft partial), it obeys that code
+ instead of running the interpreter. The result is identical, but the
+ compiled JIT code runs much faster.
There are some pcre_exec() options that are not supported for JIT exe-
cution. There are also some pattern items that JIT cannot handle.
Details are given below. In both cases, execution automatically falls
- back to the interpretive code.
+ back to the interpretive code. If you want to know whether JIT was
+ actually used for a particular match, you should arrange for a JIT
+ callback function to be set up as described in the section entitled
+ "Controlling the JIT stack" below, even if you do not need to supply a
+ non-default JIT stack. Such a callback function is called whenever JIT
+ code is about to be obeyed. If the execution options are not right for
+ JIT execution, the callback function is not obeyed.
If the JIT compiler finds an unsupported item, no JIT data is gener-
ated. You can find out if JIT execution is available after studying a
pattern by calling pcre_fullinfo() with the PCRE_INFO_JIT option. A
result of 1 means that JIT compilation was successful. A result of 0
means that JIT support is not available, or the pattern was not studied
- with PCRE_STUDY_JIT_COMPILE, or the JIT compiler was not able to handle
- the pattern.
+ with PCRE_STUDY_JIT_COMPILE etc., or the JIT compiler was not able to
+ handle the pattern.
Once a pattern has been studied, with or without JIT, it can be used as
many times as you like for matching different subject strings.
@@ -7150,9 +7184,8 @@
UNSUPPORTED OPTIONS AND PATTERN ITEMS
The only pcre_exec() options that are supported for JIT execution are
- PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and
- PCRE_NOTEMPTY_ATSTART. Note in particular that partial matching is not
- supported.
+ PCRE_NO_UTF8_CHECK, PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY,
+ PCRE_NOTEMPTY_ATSTART, PCRE_PARTIAL_HARD, and PCRE_PARTIAL_SOFT.
The unsupported pattern items are:
@@ -7169,66 +7202,66 @@
RETURN VALUES FROM JIT EXECUTION
- When a pattern is matched using JIT execution, the return values are
- the same as those given by the interpretive pcre_exec() code, with the
- addition of one new error code: PCRE_ERROR_JIT_STACKLIMIT. This means
- that the memory used for the JIT stack was insufficient. See "Control-
+ When a pattern is matched using JIT execution, the return values are
+ the same as those given by the interpretive pcre_exec() code, with the
+ addition of one new error code: PCRE_ERROR_JIT_STACKLIMIT. This means
+ that the memory used for the JIT stack was insufficient. See "Control-
ling the JIT stack" below for a discussion of JIT stack usage. For com-
- patibility with the interpretive pcre_exec() code, no more than two-
- thirds of the ovector argument is used for passing back captured sub-
+ patibility with the interpretive pcre_exec() code, no more than two-
+ thirds of the ovector argument is used for passing back captured sub-
strings.
- The error code PCRE_ERROR_MATCHLIMIT is returned by the JIT code if
- searching a very large pattern tree goes on for too long, as it is in
- the same circumstance when JIT is not used, but the details of exactly
- what is counted are not the same. The PCRE_ERROR_RECURSIONLIMIT error
+ The error code PCRE_ERROR_MATCHLIMIT is returned by the JIT code if
+ searching a very large pattern tree goes on for too long, as it is in
+ the same circumstance when JIT is not used, but the details of exactly
+ what is counted are not the same. The PCRE_ERROR_RECURSIONLIMIT error
code is never returned by JIT execution.
SAVING AND RESTORING COMPILED PATTERNS
- The code that is generated by the JIT compiler is architecture-spe-
- cific, and is also position dependent. For those reasons it cannot be
- saved (in a file or database) and restored later like the bytecode and
- other data of a compiled pattern. Saving and restoring compiled pat-
- terns is not something many people do. More detail about this facility
- is given in the pcreprecompile documentation. It should be possible to
- run pcre_study() on a saved and restored pattern, and thereby recreate
- the JIT data, but because JIT compilation uses significant resources,
- it is probably not worth doing this; you might as well recompile the
+ The code that is generated by the JIT compiler is architecture-spe-
+ cific, and is also position dependent. For those reasons it cannot be
+ saved (in a file or database) and restored later like the bytecode and
+ other data of a compiled pattern. Saving and restoring compiled pat-
+ terns is not something many people do. More detail about this facility
+ is given in the pcreprecompile documentation. It should be possible to
+ run pcre_study() on a saved and restored pattern, and thereby recreate
+ the JIT data, but because JIT compilation uses significant resources,
+ it is probably not worth doing this; you might as well recompile the
original pattern.
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
- large or complicated patterns need more than this. The error
- PCRE_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 about the use of JIT stacks in
+ stack. By default, it uses 32K on the machine stack. However, some
+ large or complicated patterns need more than this. The error
+ PCRE_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 about the use of JIT stacks in
the section entitled "JIT stack FAQ" below.
- The pcre_jit_stack_alloc() function creates a JIT stack. Its arguments
- are a starting size and a maximum size, and it returns a pointer to an
- opaque structure of type pcre_jit_stack, or NULL if there is an error.
- The pcre_jit_stack_free() function can be used to free a stack that is
- no longer needed. (For the technically minded: the address space is
+ The pcre_jit_stack_alloc() function creates a JIT stack. Its arguments
+ are a starting size and a maximum size, and it returns a pointer to an
+ opaque structure of type pcre_jit_stack, or NULL if there is an error.
+ The pcre_jit_stack_free() function can be used to free a stack that is
+ no longer needed. (For the technically minded: the address space is
allocated by mmap or VirtualAlloc.)
- JIT uses far less memory for recursion than the interpretive code, and
- a maximum stack size of 512K to 1M should be more than enough for any
+ JIT uses far less memory for recursion than the interpretive code, and
+ a maximum stack size of 512K to 1M should be more than enough for any
pattern.
- The pcre_assign_jit_stack() function specifies which stack JIT code
+ The pcre_assign_jit_stack() function specifies which stack JIT code
should use. Its arguments are as follows:
pcre_extra *extra
pcre_jit_callback callback
void *data
- The extra argument must be the result of studying a pattern with
- PCRE_STUDY_JIT_COMPILE. There are three cases for the values of the
+ The extra argument must be the result of studying a pattern with
+ PCRE_STUDY_JIT_COMPILE etc. 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
@@ -7237,26 +7270,38 @@
(2) If callback is NULL and data is not NULL, data must be
a valid JIT stack, the result of calling pcre_jit_stack_alloc().
- (3) If callback 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 result is NULL, the internal 32K stack
- is used; otherwise the return value must be a valid JIT stack,
- the result of calling pcre_jit_stack_alloc().
+ (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
+ return value must be a valid JIT stack, the result of calling
+ pcre_jit_stack_alloc().
- You may safely assign the same JIT stack to more than one pattern, as
- long as they are all matched sequentially in the same thread. In a mul-
- tithread application, each thread must use its own JIT stack.
+ A callback function is obeyed whenever JIT code is about to be run; it
+ is not obeyed when pcre_exec() is called with options that are incom-
+ patible for JIT execution. A callback function can therefore be used to
+ determine whether a match operation was executed by JIT or by the
+ interpreter.
- Strictly speaking, even more is allowed. You can assign the same stack
- to any number of patterns as long as they are not used for matching by
- multiple threads at the same time. For example, you can assign the same
- stack to all compiled patterns, and use a global mutex in the callback
- to wait until the stack is available for use. However, this is an inef-
- ficient solution, and not recommended.
+ 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 all
+ matched sequentially in the same thread. 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.
- This is a suggestion for how a typical multithreaded program might
- operate:
+ Strictly speaking, even more is allowed. You can assign the same non-
+ NULL stack to any number of patterns as long as they are not used for
+ matching by multiple threads at the same time. For example, you can
+ assign the same stack to all compiled patterns, and use 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
+ up non-default JIT stacks might operate:
+
During thread initalization
thread_local_var = pcre_jit_stack_alloc(...)
@@ -7269,7 +7314,7 @@
All the functions described in this section do nothing if JIT is not
available, and pcre_assign_jit_stack() does nothing unless the extra
argument is non-NULL and points to a pcre_extra block that is the
- result of a successful study with PCRE_STUDY_JIT_COMPILE.
+ result of a successful study with PCRE_STUDY_JIT_COMPILE etc.
JIT STACK FAQ
@@ -7329,7 +7374,7 @@
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
+ 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.
@@ -7378,11 +7423,11 @@
REVISION
- Last updated: 08 January 2012
+ Last updated: 23 February 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREPARTIAL(3) PCREPARTIAL(3)
@@ -7422,11 +7467,20 @@
matching function. If both options are set, PCRE_PARTIAL_HARD takes
precedence.
- Setting a partial matching option disables the use of any just-in-time
- code that was set up by studying the compiled pattern with the
- PCRE_STUDY_JIT_COMPILE option. It also disables two of PCRE's standard
- optimizations. PCRE remembers the last literal data unit in a pattern,
- and abandons matching immediately if it is not present in the subject
+ If you want to use partial matching with just-in-time optimized code,
+ you must call pcre_study() or pcre16_study() with one or both of these
+ options:
+
+ PCRE_STUDY_JIT_PARTIAL_SOFT_COMPILE
+ PCRE_STUDY_JIT_PARTIAL_HARD_COMPILE
+
+ PCRE_STUDY_JIT_COMPILE should also be set if you are going to run non-
+ partial matches on the same pattern. If the appropriate JIT study mode
+ has not been set for a match, the interpretive matching code is used.
+
+ Setting a partial matching option disables two of PCRE's standard opti-
+ mizations. PCRE remembers the last literal data unit in a pattern, and
+ abandons matching immediately if it is not present in the subject
string. This optimization cannot be used for a subject string that
might match only partially. If the pattern was studied, PCRE knows the
minimum length of a matching string, and does not bother to run the
@@ -7801,11 +7855,11 @@
REVISION
- Last updated: 21 January 2012
+ Last updated: 18 February 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREPRECOMPILE(3) PCREPRECOMPILE(3)
@@ -7939,8 +7993,8 @@
Last updated: 10 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREPERFORM(3) PCREPERFORM(3)
@@ -8109,8 +8163,8 @@
Last updated: 09 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCREPOSIX(3) PCREPOSIX(3)
@@ -8373,8 +8427,8 @@
Last updated: 09 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCRECPP(3) PCRECPP(3)
@@ -8715,8 +8769,8 @@
Last updated: 08 January 2012
------------------------------------------------------------------------------
-
-
+
+
PCRESAMPLE(3) PCRESAMPLE(3)
@@ -8859,8 +8913,8 @@
Last updated: 08 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
PCRESTACK(3) PCRESTACK(3)
@@ -9044,5 +9098,5 @@
Last updated: 21 January 2012
Copyright (c) 1997-2012 University of Cambridge.
------------------------------------------------------------------------------
-
-
+
+
Modified: code/trunk/doc/pcreapi.3
===================================================================
--- code/trunk/doc/pcreapi.3 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/pcreapi.3 2012-02-24 12:05:54 UTC (rev 930)
@@ -526,7 +526,7 @@
the pattern, the contents of the \fIoptions\fP argument specifies their
settings at the start of compilation and execution. The PCRE_ANCHORED,
PCRE_BSR_\fIxxx\fP, PCRE_NEWLINE_\fIxxx\fP, PCRE_NO_UTF8_CHECK, and
-PCRE_NO_START_OPT options can be set at the time of matching as well as at
+PCRE_NO_START_OPTIMIZE options can be set at the time of matching as well as at
compile time.
.P
If \fIerrptr\fP is NULL, \fBpcre_compile()\fP returns NULL immediately.
Modified: code/trunk/doc/pcrepattern.3
===================================================================
--- code/trunk/doc/pcrepattern.3 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/pcrepattern.3 2012-02-24 12:05:54 UTC (rev 930)
@@ -2598,7 +2598,12 @@
that is, if the closing parenthesis immediately follows the colon, the effect
is as if the colon were not there. Any number of these verbs may occur in a
pattern.
-.P
+.
+.
+.\" HTML <a name="nooptimize"></a>
+.SS "Optimizations that affect backtracking verbs"
+.rs
+.sp
PCRE contains some optimizations that are used to speed up matching by running
some checks at the start of each match attempt. For example, it may know the
minimum length of matching subject, or that a particular character must be
@@ -2606,7 +2611,17 @@
included backtracking verbs will not, of course, be processed. You can suppress
the start-of-match optimizations by setting the PCRE_NO_START_OPTIMIZE option
when calling \fBpcre_compile()\fP or \fBpcre_exec()\fP, or by starting the
-pattern with (*NO_START_OPT).
+pattern with (*NO_START_OPT). There is more discussion of this option in the
+section entitled
+.\" HTML <a href="pcreapi.html#execoptions">
+.\" </a>
+"Option bits for \fBpcre_exec()\fP"
+.\"
+in the
+.\" HREF
+\fBpcreapi\fP
+.\"
+documentation.
.P
Experiments with Perl suggest that it too has similar optimizations, sometimes
leading to anomalous results.
@@ -2695,9 +2710,17 @@
No match, mark = B
.sp
Note that in this unanchored example the mark is retained from the match
-attempt that started at the letter "X". Subsequent match attempts starting at
-"P" and then with an empty string do not get as far as the (*MARK) item, but
-nevertheless do not reset it.
+attempt that started at the letter "X" in the subject. Subsequent match
+attempts starting at "P" and then with an empty string do not get as far as the
+(*MARK) item, but nevertheless do not reset it.
+.P
+If you are interested in (*MARK) values after failed matches, you should
+probably set the PCRE_NO_START_OPTIMIZE option
+.\" HTML <a href="#nooptimize">
+.\" </a>
+(see above)
+.\"
+to ensure that the match is always attempted.
.
.
.SS "Verbs that act after backtracking"
@@ -2876,6 +2899,6 @@
.rs
.sp
.nf
-Last updated: 09 January 2012
+Last updated: 24 February 2012
Copyright (c) 1997-2012 University of Cambridge.
.fi
Modified: code/trunk/doc/pcretest.1
===================================================================
--- code/trunk/doc/pcretest.1 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/pcretest.1 2012-02-24 12:05:54 UTC (rev 930)
@@ -331,7 +331,7 @@
twice, the same action is taken for captured substrings. In each case the
remainder is output on the following line with a plus character following the
capture number. Note that this modifier must not immediately follow the /S
-modifier because /S+ and \S++ have other meanings.
+modifier because /S+ and /S++ have other meanings.
.P
The \fB/=\fP modifier requests that the values of all potential captured
parentheses be output after a match. By default, only those up to the highest
Modified: code/trunk/doc/pcretest.txt
===================================================================
--- code/trunk/doc/pcretest.txt 2012-02-24 11:07:47 UTC (rev 929)
+++ code/trunk/doc/pcretest.txt 2012-02-24 12:05:54 UTC (rev 930)
@@ -111,35 +111,49 @@
size megabytes.
-s or -s+ Behave as if each pattern has the /S modifier; in other
- words, force each pattern to be studied. If -s+ is used, the
- PCRE_STUDY_JIT_COMPILE flag is passed to pcre[16]_study(),
- causing just-in-time optimization to be set up if it is
- available. If the /I or /D option is present on a pattern
- (requesting output about the compiled pattern), information
- about the result of studying is not included when studying is
- caused only by -s and neither -i nor -d is present on the
- command line. This behaviour means that the output from tests
- that are run with and without -s should be identical, except
- when options that output information about the actual running
- of a match are set.
+ words, force each pattern to be studied. If -s+ is used, all
+ the JIT compile options are passed to pcre[16]_study(), caus-
+ ing just-in-time optimization to be set up if it is avail-
+ able, for both full and partial matching. Specific JIT com-
+ pile options can be selected by following -s+ with a digit in
+ the range 1 to 7, which selects the JIT compile modes as fol-
+ lows:
- The -M, -t, and -tm options, which give information about
- resources used, are likely to produce different output with
- and without -s. Output may also differ if the /C option is
- present on an individual pattern. This uses callouts to trace
- the the matching process, and this may be different between
- studied and non-studied patterns. If the pattern contains
- (*MARK) items there may also be differences, for the same
- reason. The -s command line option can be overridden for spe-
- cific patterns that should never be studied (see the /S pat-
- tern modifier below).
+ 1 normal match only
+ 2 soft partial match only
+ 3 normal match and soft partial match
+ 4 hard partial match only
+ 6 soft and hard partial match
+ 7 all three modes (default)
- -t Run each compile, study, and match many times with a timer,
- and output resulting time per compile or match (in millisec-
- onds). Do not set -m with -t, because you will then get the
- size output a zillion times, and the timing will be dis-
- torted. You can control the number of iterations that are
- used for timing by following -t with a number (as a separate
+ If -s++ is used instead of -s+ (with or without a following
+ digit), the text "(JIT)" is added to the first output line
+ after a match or no match when JIT-compiled code was actually
+ used.
+
+ If the /I or /D option is present on a pattern (requesting output about
+ the compiled pattern), information about the result of studying is not
+ included when studying is caused only by -s and neither -i nor -d is
+ present on the command line. This behaviour means that the output from
+ tests that are run with and without -s should be identical, except when
+ options that output information about the actual running of a match are
+ set.
+
+ The -M, -t, and -tm options, which give information about resources
+ used, are likely to produce different output with and without -s. Out-
+ put may also differ if the /C option is present on an individual pat-
+ tern. This uses callouts to trace the the matching process, and this
+ may be different between studied and non-studied patterns. If the pat-
+ tern contains (*MARK) items there may also be differences, for the same
+ reason. The -s command line option can be overridden for specific pat-
+ terns that should never be studied (see the /S pattern modifier below).
+
+ -t Run each compile, study, and match many times with a timer,
+ and output resulting time per compile or match (in millisec-
+ onds). Do not set -m with -t, because you will then get the
+ size output a zillion times, and the timing will be dis-
+ torted. You can control the number of iterations that are
+ used for timing by following -t with a number (as a separate
item on the command line). For example, "-t 1000" would iter-
ate 1000 times. The default is to iterate 500000 times.
@@ -149,78 +163,78 @@
DESCRIPTION
- If pcretest is given two filename arguments, it reads from the first
+ If pcretest is given two filename arguments, it reads from the first
and writes to the second. If it is given only one filename argument, it
- reads from that file and writes to stdout. Otherwise, it reads from
- stdin and writes to stdout, and prompts for each line of input, using
+ reads from that file and writes to stdout. Otherwise, it reads from
+ stdin and writes to stdout, and prompts for each line of input, using
"re>" to prompt for regular expressions, and "data>" to prompt for data
lines.
- When pcretest is built, a configuration option can specify that it
- should be linked with the libreadline library. When this is done, if
+ When pcretest is built, a configuration option can specify that it
+ should be linked with the libreadline library. When this is done, if
the input is from a terminal, it is read using the readline() function.
- This provides line-editing and history facilities. The output from the
+ This provides line-editing and history facilities. The output from the
-help option states whether or not readline() will be used.
The program handles any number of sets of input on a single input file.
- Each set starts with a regular expression, and continues with any num-
+ Each set starts with a regular expression, and continues with any num-
ber of data lines to be matched against the pattern.
- Each data line is matched separately and independently. If you want to
+ Each data line is matched separately and independently. If you want to
do multi-line matches, you have to use the \n escape sequence (or \r or
\r\n, etc., depending on the newline setting) in a single line of input
- to encode the newline sequences. There is no limit on the length of
- data lines; the input buffer is automatically extended if it is too
+ to encode the newline sequences. There is no limit on the length of
+ data lines; the input buffer is automatically extended if it is too
small.
- An empty line signals the end of the data lines, at which point a new
- regular expression is read. The regular expressions are given enclosed
+ An empty line signals the end of the data lines, at which point a new
+ regular expression is read. The regular expressions are given enclosed
in any non-alphanumeric delimiters other than backslash, for example:
/(a|bc)x+yz/
- White space before the initial delimiter is ignored. A regular expres-
- sion may be continued over several input lines, in which case the new-
- line characters are included within it. It is possible to include the
+ White space before the initial delimiter is ignored. A regular expres-
+ sion may be continued over several input lines, in which case the new-
+ line characters are included within it. It is possible to include the
delimiter within the pattern by escaping it, for example
/abc\/def/
- If you do so, the escape and the delimiter form part of the pattern,
- but since delimiters are always non-alphanumeric, this does not affect
- its interpretation. If the terminating delimiter is immediately fol-
+ If you do so, the escape and the delimiter form part of the pattern,
+ but since delimiters are always non-alphanumeric, this does not affect
+ its interpretation. If the terminating delimiter is immediately fol-
lowed by a backslash, for example,
/abc/\
- then a backslash is added to the end of the pattern. This is done to
- provide a way of testing the error condition that arises if a pattern
+ then a backslash is added to the end of the pattern. This is done to
+ provide a way of testing the error condition that arises if a pattern
finishes with a backslash, because
/abc\/
- is interpreted as the first line of a pattern that starts with "abc/",
+ is interpreted as the first line of a pattern that starts with "abc/",
causing pcretest to read the next line as a continuation of the regular
expression.
PATTERN MODIFIERS
- A pattern may be followed by any number of modifiers, which are mostly
- single characters. Following Perl usage, these are referred to below
- as, for example, "the /i modifier", even though the delimiter of the
- pattern need not always be a slash, and no slash is used when writing
- modifiers. White space may appear between the final pattern delimiter
+ A pattern may be followed by any number of modifiers, which are mostly
+ single characters. Following Perl usage, these are referred to below
+ as, for example, "the /i modifier", even though the delimiter of the
+ pattern need not always be a slash, and no slash is used when writing
+ modifiers. White space may appear between the final pattern delimiter
and the first modifier, and between the modifiers themselves.
The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE,
PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre[16]_com-
- pile() is called. These four modifier letters have the same effect as
+ pile() is called. These four modifier letters have the same effect as
they do in Perl. For example:
/caseless/i
- The following table shows additional modifiers for setting PCRE com-
+ The following table shows additional modifiers for setting PCRE com-
pile-time options that do not correspond to anything in Perl:
/8 PCRE_UTF8 ) when using the 8-bit
@@ -248,55 +262,56 @@
/<bsr_anycrlf> PCRE_BSR_ANYCRLF
/<bsr_unicode> PCRE_BSR_UNICODE
- The modifiers that are enclosed in angle brackets are literal strings
- as shown, including the angle brackets, but the letters within can be
- in either case. This example sets multiline matching with CRLF as the
+ The modifiers that are enclosed in angle brackets are literal strings
+ as shown, including the angle brackets, but the letters within can be
+ in either case. This example sets multiline matching with CRLF as the
line ending sequence:
/^abc/m<CRLF>
- As well as turning on the PCRE_UTF8/16 option, the /8 modifier causes
- all non-printing characters in output strings to be printed using the
- \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
+ As well as turning on the PCRE_UTF8/16 option, the /8 modifier causes
+ all non-printing characters in output strings to be printed using the
+ \x{hh...} notation. Otherwise, those less than 0x100 are output in hex
without the curly brackets.
- Full details of the PCRE options are given in the pcreapi documenta-
+ Full details of the PCRE options are given in the pcreapi documenta-
tion.
Finding all matches in a string
- Searching for all possible matches within each subject string can be
- requested by the /g or /G modifier. After finding a match, PCRE is
+ Searching for all possible matches within each subject string can be
+ requested by the /g or /G modifier. After finding a match, PCRE is
called again to search the remainder of the subject string. The differ-
ence between /g and /G is that the former uses the startoffset argument
- to pcre[16]_exec() to start searching at a new point within the entire
- string (which is in effect what Perl does), whereas the latter passes
- over a shortened substring. This makes a difference to the matching
+ to pcre[16]_exec() to start searching at a new point within the entire
+ string (which is in effect what Perl does), whereas the latter passes
+ over a shortened substring. This makes a difference to the matching
process if the pattern begins with a lookbehind assertion (including \b
or \B).
- If any call to pcre[16]_exec() in a /g or /G sequence matches an empty
- string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
- PCRE_ANCHORED flags set in order to search for another, non-empty,
- match at the same point. If this second match fails, the start offset
- is advanced, and the normal match is retried. This imitates the way
+ If any call to pcre[16]_exec() in a /g or /G sequence matches an empty
+ string, the next call is done with the PCRE_NOTEMPTY_ATSTART and
+ PCRE_ANCHORED flags set in order to search for another, non-empty,
+ match at the same point. If this second match fails, the start offset
+ is advanced, and the normal match is retried. This imitates the way
Perl handles such cases when using the /g modifier or the split() func-
- tion. Normally, the start offset is advanced by one character, but if
- the newline convention recognizes CRLF as a newline, and the current
+ tion. Normally, the start offset is advanced by one character, but if
+ the newline convention recognizes CRLF as a newline, and the current
character is CR followed by LF, an advance of two is used.
Other modifiers
There are yet more modifiers for controlling the way pcretest operates.
- The /+ modifier requests that as well as outputting the substring that
- matched the entire pattern, pcretest should in addition output the
- remainder of the subject string. This is useful for tests where the
- subject contains multiple copies of the same substring. If the + modi-
- fier appears twice, the same action is taken for captured substrings.
- In each case the remainder is output on the following line with a plus
- character following the capture number. Note that this modifier must
- not immediately follow the /S modifier because /S+ has another meaning.
+ The /+ modifier requests that as well as outputting the substring that
+ matched the entire pattern, pcretest should in addition output the
+ remainder of the subject string. This is useful for tests where the
+ subject contains multiple copies of the same substring. If the + modi-
+ fier appears twice, the same action is taken for captured substrings.
+ In each case the remainder is output on the following line with a plus
+ character following the capture number. Note that this modifier must
+ not immediately follow the /S modifier because /S+ and /S++ have other
+ meanings.
The /= modifier requests that the values of all potential captured
parentheses be output after a match. By default, only those up to the
@@ -368,16 +383,31 @@
different when the pattern is studied.
If the /S modifier is immediately followed by a + character, the call
- to pcre[16]_study() is made with the PCRE_STUDY_JIT_COMPILE option,
- requesting just-in-time optimization support if it is available. Note
- that there is also a /+ modifier; it must not be given immediately
- after /S because this will be misinterpreted. If JIT studying is suc-
- cessful, it will automatically be used when pcre[16]_exec() is run,
- except when incompatible run-time options are specified. These include
- the partial matching options; a complete list is given in the pcrejit
- documentation. See also the \J escape sequence below for a way of set-
- ting the size of the JIT stack.
+ to pcre[16]_study() is made with all the JIT study options, requesting
+ just-in-time optimization support if it is available, for both normal
+ and partial matching. If you want to restrict the JIT compiling modes,
+ you can follow /S+ with a digit in the range 1 to 7:
+ 1 normal match only
+ 2 soft partial match only
+ 3 normal match and soft partial match
+ 4 hard partial match only
+ 6 soft and hard partial match
+ 7 all three modes (default)
+
+ If /S++ is used instead of /S+ (with or without a following digit), the
+ text "(JIT)" is added to the first output line after a match or no
+ match when JIT-compiled code was actually used.
+
+ Note that there is also an independent /+ modifier; it must not be
+ given immediately after /S or /S+ because this will be misinterpreted.
+
+ If JIT studying is successful, the compiled JIT code will automatically
+ be used when pcre[16]_exec() is run, except when incompatible run-time
+ options are specified. For more details, see the pcrejit documentation.
+ See also the \J escape sequence below for a way of setting the size of
+ the JIT stack.
+
The /T modifier must be followed by a single digit. It causes a spe-
cific set of built-in character tables to be passed to pcre[16]_com-
pile(). It is used in the standard PCRE tests to check behaviour with
@@ -869,5 +899,5 @@
REVISION
- Last updated: 14 January 2012
+ Last updated: 21 February 2012
Copyright (c) 1997-2012 University of Cambridge.
