Revision: 1142
http://www.exim.org/viewvc/pcre2?view=rev&revision=1142
Author: ph10
Date: 2019-07-22 17:30:44 +0100 (Mon, 22 Jul 2019)
Log Message:
-----------
More partial match tweaks.
Modified Paths:
--------------
code/trunk/ChangeLog
code/trunk/doc/html/pcre2api.html
code/trunk/doc/html/pcre2partial.html
code/trunk/doc/pcre2.txt
code/trunk/doc/pcre2api.3
code/trunk/doc/pcre2partial.3
code/trunk/src/pcre2_dfa_match.c
code/trunk/src/pcre2_intmodedep.h
code/trunk/src/pcre2_match.c
code/trunk/testdata/testinput2
code/trunk/testdata/testinput6
code/trunk/testdata/testoutput2
code/trunk/testdata/testoutput6
Modified: code/trunk/ChangeLog
===================================================================
--- code/trunk/ChangeLog 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/ChangeLog 2019-07-22 16:30:44 UTC (rev 1142)
@@ -104,7 +104,11 @@
is another situation where adding characters to the current subject can
lead to a full match. Example: /c*+(?<=[bc])/ with subject "ab".
- (b) An empty string partial hard match can be returned for \z and \Z as it
+ (b) Similarly, if a pattern could match an empty string, an empty partial
+ match may be given. Example: /(?![ab]).*/ with subject "ab". This case
+ applies only to PCRE2_PARTIAL_HARD.
+
+ (c) An empty string partial hard match can be returned for \z and \Z as it
is documented that they shouldn't match.
Modified: code/trunk/doc/html/pcre2api.html
===================================================================
--- code/trunk/doc/html/pcre2api.html 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/html/pcre2api.html 2019-07-22 16:30:44 UTC (rev 1142)
@@ -2057,7 +2057,7 @@
PCRE2_ERROR_BADOPTION the value of <i>what</i> was invalid
PCRE2_ERROR_UNSET the requested field is not set
</pre>
-The "magic number" is placed at the start of each compiled pattern as an simple
+The "magic number" is placed at the start of each compiled pattern as a simple
check against passing an arbitrary memory pointer. Here is a typical call of
<b>pcre2_pattern_info()</b>, to obtain the length of the compiled pattern:
<pre>
@@ -2114,7 +2114,7 @@
PCRE2_INFO_BACKREFMAX
</pre>
Return the number of the highest backreference in the pattern. The third
-argument should point to an <b>uint32_t</b> variable. Named capture groups
+argument should point to a <b>uint32_t</b> variable. Named capture groups
acquire numbers as well as names, and these count towards the highest
backreference. Backreferences such as \4 or \g{12} match the captured
characters of the given group, but in addition, the check that a capture
@@ -2132,7 +2132,7 @@
</pre>
Return the highest capture group number in the pattern. In patterns where (?|
is not used, this is also the total number of capture groups. The third
-argument should point to an <b>uint32_t</b> variable.
+argument should point to a <b>uint32_t</b> variable.
<pre>
PCRE2_INFO_DEPTHLIMIT
</pre>
@@ -2157,7 +2157,7 @@
PCRE2_INFO_FIRSTCODETYPE
</pre>
Return information about the first code unit of any matched string, for a
-non-anchored pattern. The third argument should point to an <b>uint32_t</b>
+non-anchored pattern. The third argument should point to a <b>uint32_t</b>
variable. If there is a fixed first value, for example, the letter "c" from a
pattern such as (cat|cow|coyote), 1 is returned, and the value can be retrieved
using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed first value, but it is
@@ -2169,7 +2169,7 @@
</pre>
Return the value of the first code unit of any matched string for a pattern
where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0. The third
-argument should point to an <b>uint32_t</b> variable. In the 8-bit library, the
+argument should point to a <b>uint32_t</b> variable. In the 8-bit library, the
value is always less than 256. In the 16-bit library the value can be up to
0xffff. In the 32-bit library in UTF-32 mode the value can be up to 0x10ffff,
and up to 0xffffffff when not using UTF-32 mode.
@@ -2185,12 +2185,12 @@
PCRE2_INFO_HASBACKSLASHC
</pre>
Return 1 if the pattern contains any instances of \C, otherwise 0. The third
-argument should point to an <b>uint32_t</b> variable.
+argument should point to a <b>uint32_t</b> variable.
<pre>
PCRE2_INFO_HASCRORLF
</pre>
Return 1 if the pattern contains any explicit matches for CR or LF characters,
-otherwise 0. The third argument should point to an <b>uint32_t</b> variable. An
+otherwise 0. The third argument should point to a <b>uint32_t</b> variable. An
explicit match is either a literal CR or LF character, or \r or \n or one of
the equivalent hexadecimal or octal escape sequences.
<pre>
@@ -2206,7 +2206,7 @@
PCRE2_INFO_JCHANGED
</pre>
Return 1 if the (?J) or (?-J) option setting is used in the pattern, otherwise
-0. The third argument should point to an <b>uint32_t</b> variable. (?J) and
+0. The third argument should point to a <b>uint32_t</b> variable. (?J) and
(?-J) set and unset the local PCRE2_DUPNAMES option, respectively.
<pre>
PCRE2_INFO_JITSIZE
@@ -2218,7 +2218,7 @@
PCRE2_INFO_LASTCODETYPE
</pre>
Returns 1 if there is a rightmost literal code unit that must exist in any
-matched string, other than at its start. The third argument should point to an
+matched string, other than at its start. The third argument should point to a
<b>uint32_t</b> variable. If there is no such value, 0 is returned. When 1 is
returned, the code unit value itself can be retrieved using
PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last literal value is
@@ -2231,12 +2231,12 @@
Return the value of the rightmost literal code unit that must exist in any
matched string, other than at its start, for a pattern where
PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argument
-should point to an <b>uint32_t</b> variable.
+should point to a <b>uint32_t</b> variable.
<pre>
PCRE2_INFO_MATCHEMPTY
</pre>
Return 1 if the pattern might match an empty string, otherwise 0. The third
-argument should point to an <b>uint32_t</b> variable. When a pattern contains
+argument should point to a <b>uint32_t</b> variable. When a pattern contains
recursive subroutine calls it is not always possible to determine whether or
not it can match an empty string. PCRE2 takes a cautious approach and returns 1
in such cases.
@@ -2279,7 +2279,7 @@
returned. Otherwise the returned value is 0. This value is not computed when
PCRE2_NO_START_OPTIMIZE is set. The value is a number of characters, which in
UTF mode may be different from the number of code units. The third argument
-should point to an <b>uint32_t</b> variable. The value is a lower bound to the
+should point to a <b>uint32_t</b> variable. The value is a lower bound to the
length of any matching string. There may not be any strings of that length that
do actually match, but every string that does match is at least that long.
<pre>
@@ -2726,7 +2726,8 @@
These options turn on the partial matching feature. A partial match occurs if
the end of the subject string is reached successfully, but there are not enough
subject characters to complete the match. In addition, either at least one
-character must have been inspected or the pattern must contain a lookbehind.
+character must have been inspected or the pattern must contain a lookbehind, or
+the pattern must be one that could match an empty string.
</P>
<P>
If this situation arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD)
@@ -3850,7 +3851,7 @@
</P>
<br><a name="SEC42" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 20 July 2019
+Last updated: 22 July 2019
<br>
Copyright © 1997-2019 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcre2partial.html
===================================================================
--- code/trunk/doc/html/pcre2partial.html 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/html/pcre2partial.html 2019-07-22 16:30:44 UTC (rev 1142)
@@ -80,16 +80,18 @@
A partial match occurs during a call to <b>pcre2_match()</b> when the end of the
subject string is reached successfully, but matching cannot continue because
more characters are needed, and in addition, either at least one character in
-the subject has been inspected or the pattern contains a lookbehind. An
+the subject has been inspected or the pattern contains a lookbehind, or (when
+PCRE2_PARTIAL_HARD is set) the pattern could match an empty string. An
inspected character need not form part of the final matched string; lookbehind
assertions and the \K escape sequence provide ways of inspecting characters
before the start of a matched string.
</P>
<P>
-The two additional requirements define the cases where adding more characters
-to the existing subject may complete the match. Without these conditions there
-would be a partial match of an empty string at the end of the subject for all
-unanchored patterns (and also for anchored patterns if the subject itself is
+The three additional requirements define the cases where adding more characters
+to the existing subject may complete the same match that would occur if they
+had all been present in the first place. Without these conditions there would
+be a partial match of an empty string at the end of the subject for all
+unanchored patterns (and also for anchored patterns if the subject itself is
empty).
</P>
<P>
@@ -449,7 +451,7 @@
</P>
<br><a name="SEC10" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 21 July 2019
+Last updated: 22 July 2019
<br>
Copyright © 1997-2019 University of Cambridge.
<br>
Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/pcre2.txt 2019-07-22 16:30:44 UTC (rev 1142)
@@ -2013,8 +2013,8 @@
PCRE2_ERROR_BADOPTION the value of what was invalid
PCRE2_ERROR_UNSET the requested field is not set
- The "magic number" is placed at the start of each compiled pattern as
- an simple check against passing an arbitrary memory pointer. Here is a
+ The "magic number" is placed at the start of each compiled pattern as a
+ simple check against passing an arbitrary memory pointer. Here is a
typical call of pcre2_pattern_info(), to obtain the length of the com-
piled pattern:
@@ -2073,7 +2073,7 @@
PCRE2_INFO_BACKREFMAX
Return the number of the highest backreference in the pattern. The
- third argument should point to an uint32_t variable. Named capture
+ third argument should point to a uint32_t variable. Named capture
groups acquire numbers as well as names, and these count towards the
highest backreference. Backreferences such as \4 or \g{12} match the
captured characters of the given group, but in addition, the check that
@@ -2091,7 +2091,7 @@
Return the highest capture group number in the pattern. In patterns
where (?| is not used, this is also the total number of capture groups.
- The third argument should point to an uint32_t variable.
+ The third argument should point to a uint32_t variable.
PCRE2_INFO_DEPTHLIMIT
@@ -2117,7 +2117,7 @@
PCRE2_INFO_FIRSTCODETYPE
Return information about the first code unit of any matched string, for
- a non-anchored pattern. The third argument should point to an uint32_t
+ a non-anchored pattern. The third argument should point to a uint32_t
variable. If there is a fixed first value, for example, the letter "c"
from a pattern such as (cat|cow|coyote), 1 is returned, and the value
can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
@@ -2129,7 +2129,7 @@
Return the value of the first code unit of any matched string for a
pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
- The third argument should point to an uint32_t variable. In the 8-bit
+ The third argument should point to a uint32_t variable. In the 8-bit
library, the value is always less than 256. In the 16-bit library the
value can be up to 0xffff. In the 32-bit library in UTF-32 mode the
value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32
@@ -2147,12 +2147,12 @@
PCRE2_INFO_HASBACKSLASHC
Return 1 if the pattern contains any instances of \C, otherwise 0. The
- third argument should point to an uint32_t variable.
+ third argument should point to a uint32_t variable.
PCRE2_INFO_HASCRORLF
Return 1 if the pattern contains any explicit matches for CR or LF
- characters, otherwise 0. The third argument should point to an uint32_t
+ characters, otherwise 0. The third argument should point to a uint32_t
variable. An explicit match is either a literal CR or LF character, or
\r or \n or one of the equivalent hexadecimal or octal escape se-
quences.
@@ -2169,7 +2169,7 @@
PCRE2_INFO_JCHANGED
Return 1 if the (?J) or (?-J) option setting is used in the pattern,
- otherwise 0. The third argument should point to an uint32_t variable.
+ otherwise 0. The third argument should point to a uint32_t variable.
(?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
tively.
@@ -2183,13 +2183,13 @@
Returns 1 if there is a rightmost literal code unit that must exist in
any matched string, other than at its start. The third argument should
- point to an uint32_t variable. If there is no such value, 0 is re-
- turned. When 1 is returned, the code unit value itself can be retrieved
- using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last literal
- value is recorded only if it follows something of variable length. For
- example, for the pattern /^a\d+z\d+/ the returned value is 1 (with "z"
- returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned
- value is 0.
+ point to a uint32_t variable. If there is no such value, 0 is returned.
+ When 1 is returned, the code unit value itself can be retrieved using
+ PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last literal value is
+ recorded only if it follows something of variable length. For example,
+ for the pattern /^a\d+z\d+/ the returned value is 1 (with "z" returned
+ from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/ the returned value is
+ 0.
PCRE2_INFO_LASTCODEUNIT
@@ -2196,15 +2196,15 @@
Return the value of the rightmost literal code unit that must exist in
any matched string, other than at its start, for a pattern where
PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argu-
- ment should point to an uint32_t variable.
+ ment should point to a uint32_t variable.
PCRE2_INFO_MATCHEMPTY
Return 1 if the pattern might match an empty string, otherwise 0. The
- third argument should point to an uint32_t variable. When a pattern
- contains recursive subroutine calls it is not always possible to deter-
- mine whether or not it can match an empty string. PCRE2 takes a cau-
- tious approach and returns 1 in such cases.
+ third argument should point to a uint32_t variable. When a pattern con-
+ tains recursive subroutine calls it is not always possible to determine
+ whether or not it can match an empty string. PCRE2 takes a cautious ap-
+ proach and returns 1 in such cases.
PCRE2_INFO_MATCHLIMIT
@@ -2244,7 +2244,7 @@
value is returned. Otherwise the returned value is 0. This value is not
computed when PCRE2_NO_START_OPTIMIZE is set. The value is a number of
characters, which in UTF mode may be different from the number of code
- units. The third argument should point to an uint32_t variable. The
+ units. The third argument should point to a uint32_t variable. The
value is a lower bound to the length of any matching string. There may
not be any strings of that length that do actually match, but every
string that does match is at least that long.
@@ -2663,18 +2663,19 @@
curs if the end of the subject string is reached successfully, but
there are not enough subject characters to complete the match. In addi-
tion, either at least one character must have been inspected or the
- pattern must contain a lookbehind.
+ pattern must contain a lookbehind, or the pattern must be one that
+ could match an empty string.
- If this situation arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PAR-
+ If this situation arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PAR-
TIAL_HARD) is set, matching continues by testing any remaining alterna-
- tives. Only if no complete match can be found is PCRE2_ERROR_PARTIAL
- returned instead of PCRE2_ERROR_NOMATCH. In other words, PCRE2_PAR-
- TIAL_SOFT specifies that the caller is prepared to handle a partial
+ tives. Only if no complete match can be found is PCRE2_ERROR_PARTIAL
+ returned instead of PCRE2_ERROR_NOMATCH. In other words, PCRE2_PAR-
+ TIAL_SOFT specifies that the caller is prepared to handle a partial
match, but only if no complete match can be found.
- If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
- case, if a partial match is found, pcre2_match() immediately returns
- PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
+ If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
+ case, if a partial match is found, pcre2_match() immediately returns
+ PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid-
ered to be more important that an alternative complete match.
@@ -2684,38 +2685,38 @@
NEWLINE HANDLING WHEN MATCHING
- When PCRE2 is built, a default newline convention is set; this is usu-
- ally the standard convention for the operating system. The default can
- be overridden in a compile context by calling pcre2_set_newline(). It
- can also be overridden by starting a pattern string with, for example,
- (*CRLF), as described in the section on newline conventions in the
- pcre2pattern page. During matching, the newline choice affects the be-
- haviour of the dot, circumflex, and dollar metacharacters. It may also
- alter the way the match starting position is advanced after a match
+ When PCRE2 is built, a default newline convention is set; this is usu-
+ ally the standard convention for the operating system. The default can
+ be overridden in a compile context by calling pcre2_set_newline(). It
+ can also be overridden by starting a pattern string with, for example,
+ (*CRLF), as described in the section on newline conventions in the
+ pcre2pattern page. During matching, the newline choice affects the be-
+ haviour of the dot, circumflex, and dollar metacharacters. It may also
+ alter the way the match starting position is advanced after a match
failure for an unanchored pattern.
When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is
- set as the newline convention, and a match attempt for an unanchored
+ set as the newline convention, and a match attempt for an unanchored
pattern fails when the current starting position is at a CRLF sequence,
- and the pattern contains no explicit matches for CR or LF characters,
- the match position is advanced by two characters instead of one, in
+ and the pattern contains no explicit matches for CR or LF characters,
+ the match position is advanced by two characters instead of one, in
other words, to after the CRLF.
The above rule is a compromise that makes the most common cases work as
- expected. For example, if the pattern is .+A (and the PCRE2_DOTALL op-
- tion 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-
+ expected. For example, if the pattern is .+A (and the PCRE2_DOTALL op-
+ tion 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-
tains an explicit CR or LF reference, and so advances only by one char-
acter after the first failure.
An explicit match for CR of LF is either a literal appearance of one of
- those characters in the pattern, or one of the \r or \n or equivalent
+ those characters in the pattern, or one of the \r or \n or equivalent
octal or hexadecimal escape sequences. Implicit matches such as [^X] do
- not count, nor does \s, even though it includes CR and LF in the char-
+ not count, nor does \s, even though it includes CR and LF in the char-
acters that it matches.
- Notwithstanding the above, anomalous effects may still occur when CRLF
+ Notwithstanding the above, anomalous effects may still occur when CRLF
is a valid newline sequence and explicit \r or \n escapes appear in the
pattern.
@@ -2726,82 +2727,82 @@
PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data);
- In general, a pattern matches a certain portion of the subject, and in
- addition, further substrings from the subject may be picked out by
- parenthesized parts of the pattern. Following the usage in Jeffrey
- Friedl's book, this is called "capturing" in what follows, and the
- phrase "capture group" (Perl terminology) is used for a fragment of a
- pattern that picks out a substring. PCRE2 supports several other kinds
+ In general, a pattern matches a certain portion of the subject, and in
+ addition, further substrings from the subject may be picked out by
+ parenthesized parts of the pattern. Following the usage in Jeffrey
+ Friedl's book, this is called "capturing" in what follows, and the
+ phrase "capture group" (Perl terminology) is used for a fragment of a
+ pattern that picks out a substring. PCRE2 supports several other kinds
of parenthesized group that do not cause substrings to be captured. The
- pcre2_pattern_info() function can be used to find out how many capture
+ pcre2_pattern_info() function can be used to find out how many capture
groups there are in a compiled pattern.
- You can use auxiliary functions for accessing captured substrings by
+ You can use auxiliary functions for accessing captured substrings by
number or by name, as described in sections below.
Alternatively, you can make direct use of the vector of PCRE2_SIZE val-
- ues, called the ovector, which contains the offsets of captured
- strings. It is part of the match data block. The function
- pcre2_get_ovector_pointer() returns the address of the ovector, and
+ ues, called the ovector, which contains the offsets of captured
+ strings. It is part of the match data block. The function
+ pcre2_get_ovector_pointer() returns the address of the ovector, and
pcre2_get_ovector_count() returns the number of pairs of values it con-
tains.
Within the ovector, the first in each pair of values is set to the off-
set of the first code unit of a substring, and the second is set to the
- offset of the first code unit after the end of a substring. These val-
- ues are always code unit offsets, not character offsets. That is, they
+ offset of the first code unit after the end of a substring. These val-
+ ues are always code unit offsets, not character offsets. That is, they
are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit li-
brary, and 32-bit offsets in the 32-bit library.
- After a partial match (error return PCRE2_ERROR_PARTIAL), only the
- first pair of offsets (that is, ovector[0] and ovector[1]) are set.
- They identify the part of the subject that was partially matched. See
+ After a partial match (error return PCRE2_ERROR_PARTIAL), only the
+ first pair of offsets (that is, ovector[0] and ovector[1]) are set.
+ They identify the part of the subject that was partially matched. See
the pcre2partial documentation for details of partial matching.
- After a fully successful match, the first pair of offsets identifies
- the portion of the subject string that was matched by the entire pat-
- tern. The next pair is used for the first captured substring, and so
- on. The value returned by pcre2_match() is one more than the highest
- numbered pair that has been set. For example, if two substrings have
- been captured, the returned value is 3. If there are no captured sub-
+ After a fully successful match, the first pair of offsets identifies
+ the portion of the subject string that was matched by the entire pat-
+ tern. The next pair is used for the first captured substring, and so
+ on. The value returned by pcre2_match() is one more than the highest
+ numbered pair that has been set. For example, if two substrings have
+ been captured, the returned value is 3. If there are no captured sub-
strings, the return value from a successful match is 1, indicating that
just the first pair of offsets has been set.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
+ the match. For example, if the pattern (?=ab\K) is matched against
"ab", the start and end offset values for the match are 2 and 0.
- If a capture group is matched repeatedly within a single match opera-
+ If a capture group is matched repeatedly within a single match opera-
tion, it is the last portion of the subject that it matched that is re-
turned.
If the ovector is too small to hold all the captured substring offsets,
- as much as possible is filled in, and the function returns a value of
- zero. If captured substrings are not of interest, pcre2_match() may be
+ as much as possible is filled in, and the function returns a value of
+ zero. If captured substrings are not of interest, pcre2_match() may be
called with a match data block whose ovector is of minimum length (that
is, one pair).
- It is possible for capture group number n+1 to match some part of the
- subject when group n has not been used at all. For example, if the
+ It is possible for capture group number n+1 to match some part of the
+ subject when group n has not been used at all. For example, if the
string "abc" is matched against the pattern (a|(z))(bc) the return from
- the function is 4, and groups 1 and 3 are matched, but 2 is not. When
- this happens, both values in the offset pairs corresponding to unused
+ the function is 4, and groups 1 and 3 are matched, but 2 is not. When
+ this happens, both values in the offset pairs corresponding to unused
groups are set to PCRE2_UNSET.
- Offset values that correspond to unused groups at the end of the ex-
- pression are also set to PCRE2_UNSET. For example, if the string "abc"
- is matched against the pattern (abc)(x(yz)?)? groups 2 and 3 are not
- matched. The return from the function is 2, because the highest used
- capture group number is 1. The offsets for for the second and third
- capture groupss (assuming the vector is large enough, of course) are
+ Offset values that correspond to unused groups at the end of the ex-
+ pression are also set to PCRE2_UNSET. For example, if the string "abc"
+ is matched against the pattern (abc)(x(yz)?)? groups 2 and 3 are not
+ matched. The return from the function is 2, because the highest used
+ capture group number is 1. The offsets for for the second and third
+ capture groupss (assuming the vector is large enough, of course) are
set to PCRE2_UNSET.
Elements in the ovector that do not correspond to capturing parentheses
in the pattern are never changed. That is, if a pattern contains n cap-
turing parentheses, no more than ovector[0] to ovector[2n+1] are set by
- pcre2_match(). The other elements retain whatever values they previ-
- ously had. After a failed match attempt, the contents of the ovector
+ pcre2_match(). The other elements retain whatever values they previ-
+ ously had. After a failed match attempt, the contents of the ovector
are unchanged.
@@ -2811,25 +2812,25 @@
PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data);
- As well as the offsets in the ovector, other information about a match
- is retained in the match data block and can be retrieved by the above
- functions in appropriate circumstances. If they are called at other
+ As well as the offsets in the ovector, other information about a match
+ is retained in the match data block and can be retrieved by the above
+ functions in appropriate circumstances. If they are called at other
times, the result is undefined.
- After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
- failure to match (PCRE2_ERROR_NOMATCH), a mark name may be available.
- The function pcre2_get_mark() can be called to access this name, which
- can be specified in the pattern by any of the backtracking control
+ After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
+ failure to match (PCRE2_ERROR_NOMATCH), a mark name may be available.
+ The function pcre2_get_mark() can be called to access this name, which
+ can be specified in the pattern by any of the backtracking control
verbs, not just (*MARK). The same function applies to all the verbs. It
returns a pointer to the zero-terminated name, which is within the com-
piled pattern. If no name is available, NULL is returned. The length of
- the name (excluding the terminating zero) is stored in the code unit
- that precedes the name. You should use this length instead of relying
+ the name (excluding the terminating zero) is stored in the code unit
+ that precedes the name. You should use this length instead of relying
on the terminating zero if the name might contain a binary zero.
- After a successful match, the name that is returned is the last mark
+ After a successful match, the name that is returned is the last mark
name encountered on the matching path through the pattern. Instances of
- backtracking verbs without names do not count. Thus, for example, if
+ backtracking verbs without names do not count. Thus, for example, if
the matching path contains (*MARK:A)(*PRUNE), the name "A" is returned.
After a "no match" or a partial match, the last encountered name is re-
turned. For example, consider this pattern:
@@ -2836,30 +2837,30 @@
^(*MARK:A)((*MARK:B)a|b)c
- When it matches "bc", the returned name is A. The B mark is "seen" in
- the first branch of the group, but it is not on the matching path. On
- the other hand, when this pattern fails to match "bx", the returned
+ When it matches "bc", the returned name is A. The B mark is "seen" in
+ the first branch of the group, but it is not on the matching path. On
+ the other hand, when this pattern fails to match "bx", the returned
name is B.
- Warning: By default, certain start-of-match optimizations are used to
- give a fast "no match" result in some situations. For example, if the
- anchoring is removed from the pattern above, there is an initial check
- for the presence of "c" in the subject before running the matching en-
+ Warning: By default, certain start-of-match optimizations are used to
+ give a fast "no match" result in some situations. For example, if the
+ anchoring is removed from the pattern above, there is an initial check
+ for the presence of "c" in the subject before running the matching en-
gine. This check fails for "bx", causing a match failure without seeing
- any marks. You can disable the start-of-match optimizations by setting
- the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or by starting
+ any marks. You can disable the start-of-match optimizations by setting
+ the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or by starting
the pattern with (*NO_START_OPT).
- After a successful match, a partial match, or one of the invalid UTF
- errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
+ After a successful match, a partial match, or one of the invalid UTF
+ errors (for example, PCRE2_ERROR_UTF8_ERR5), pcre2_get_startchar() can
be called. After a successful or partial match it returns the code unit
- offset of the character at which the match started. For a non-partial
- match, this can be different to the value of ovector[0] if the pattern
- contains the \K escape sequence. After a partial match, however, this
- value is always the same as ovector[0] because \K does not affect the
+ offset of the character at which the match started. For a non-partial
+ match, this can be different to the value of ovector[0] if the pattern
+ contains the \K escape sequence. After a partial match, however, this
+ value is always the same as ovector[0] because \K does not affect the
result of a partial match.
- After a UTF check failure, pcre2_get_startchar() can be used to obtain
+ After a UTF check failure, pcre2_get_startchar() can be used to obtain
the code unit offset of the invalid UTF character. Details are given in
the pcre2unicode page.
@@ -2866,14 +2867,14 @@
ERROR RETURNS FROM pcre2_match()
- If pcre2_match() fails, it returns a negative number. This can be con-
- verted to a text string by calling the pcre2_get_error_message() func-
- tion (see "Obtaining a textual error message" below). Negative error
- codes are also returned by other functions, and are documented with
- them. The codes are given names in the header file. If UTF checking is
+ If pcre2_match() fails, it returns a negative number. This can be con-
+ verted to a text string by calling the pcre2_get_error_message() func-
+ tion (see "Obtaining a textual error message" below). Negative error
+ codes are also returned by other functions, and are documented with
+ them. The codes are given names in the header file. If UTF checking is
in force and an invalid UTF subject string is detected, one of a number
- of UTF-specific negative error codes is returned. Details are given in
- the pcre2unicode page. The following are the other errors that may be
+ of UTF-specific negative error codes is returned. Details are given in
+ the pcre2unicode page. The following are the other errors that may be
returned by pcre2_match():
PCRE2_ERROR_NOMATCH
@@ -2882,20 +2883,20 @@
PCRE2_ERROR_PARTIAL
- The subject string did not match, but it did match partially. See the
+ The subject string did not match, but it did match partially. See the
pcre2partial documentation for details of partial matching.
PCRE2_ERROR_BADMAGIC
PCRE2 stores a 4-byte "magic number" at the start of the compiled code,
- to catch the case when it is passed a junk pointer. This is the error
+ to catch the case when it is passed a junk pointer. This is the error
that is returned when the magic number is not present.
PCRE2_ERROR_BADMODE
- This error is given when a compiled pattern is passed to a function in
- a library of a different code unit width, for example, a pattern com-
- piled by the 8-bit library is passed to a 16-bit or 32-bit library
+ This error is given when a compiled pattern is passed to a function in
+ a library of a different code unit width, for example, a pattern com-
+ piled by the 8-bit library is passed to a 16-bit or 32-bit library
function.
PCRE2_ERROR_BADOFFSET
@@ -2909,15 +2910,15 @@
PCRE2_ERROR_BADUTFOFFSET
The UTF code unit sequence that was passed as a subject was checked and
- found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
- value of startoffset did not point to the beginning of a UTF character
+ found to be valid (the PCRE2_NO_UTF_CHECK option was not set), but the
+ value of startoffset did not point to the beginning of a UTF character
or the end of the subject.
PCRE2_ERROR_CALLOUT
- This error is never generated by pcre2_match() itself. It is provided
- for use by callout functions that want to cause pcre2_match() or
- pcre2_callout_enumerate() to return a distinctive error code. See the
+ This error is never generated by pcre2_match() itself. It is provided
+ for use by callout functions that want to cause pcre2_match() or
+ pcre2_callout_enumerate() to return a distinctive error code. See the
pcre2callout documentation for details.
PCRE2_ERROR_DEPTHLIMIT
@@ -2930,7 +2931,7 @@
PCRE2_ERROR_INTERNAL
- An unexpected internal error has occurred. This error could be caused
+ An unexpected internal error has occurred. This error could be caused
by a bug in PCRE2 or by overwriting of the compiled pattern.
PCRE2_ERROR_JIT_STACKLIMIT
@@ -2937,7 +2938,7 @@
This error is returned when a pattern that was successfully studied us-
ing JIT is being matched, but the memory available for the just-in-time
- processing stack is not large enough. See the pcre2jit documentation
+ processing stack is not large enough. See the pcre2jit documentation
for more details.
PCRE2_ERROR_MATCHLIMIT
@@ -2946,11 +2947,11 @@
PCRE2_ERROR_NOMEMORY
- If a pattern contains many nested backtracking points, heap memory is
- used to remember them. This error is given when the memory allocation
- function (default or custom) fails. Note that a different error,
- PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
- the heap limit. PCRE2_ERROR_NOMEMORY is also returned if
+ If a pattern contains many nested backtracking points, heap memory is
+ used to remember them. This error is given when the memory allocation
+ function (default or custom) fails. Note that a different error,
+ PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
+ the heap limit. PCRE2_ERROR_NOMEMORY is also returned if
PCRE2_COPY_MATCHED_SUBJECT is set and memory allocation fails.
PCRE2_ERROR_NULL
@@ -2959,12 +2960,12 @@
PCRE2_ERROR_RECURSELOOP
- This error is returned when pcre2_match() detects a recursion loop
- within the pattern. Specifically, it means that either the whole pat-
+ This error is returned when pcre2_match() detects a recursion loop
+ within the pattern. Specifically, it means that either the whole pat-
tern or a capture group has been called recursively for the second time
- at the same position in the subject string. Some simple patterns that
- might do this are detected and faulted at compile time, but more com-
- plicated cases, in particular mutual recursions between two different
+ at the same position in the subject string. Some simple patterns that
+ might do this are detected and faulted at compile time, but more com-
+ plicated cases, in particular mutual recursions between two different
groups, cannot be detected until matching is attempted.
@@ -2973,20 +2974,20 @@
int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
PCRE2_SIZE bufflen);
- A text message for an error code from any PCRE2 function (compile,
- match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
- sage(). The code is passed as the first argument, with the remaining
- two arguments specifying a code unit buffer and its length in code
- units, into which the text message is placed. The message is returned
- in code units of the appropriate width for the library that is being
+ A text message for an error code from any PCRE2 function (compile,
+ match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
+ sage(). The code is passed as the first argument, with the remaining
+ two arguments specifying a code unit buffer and its length in code
+ units, into which the text message is placed. The message is returned
+ in code units of the appropriate width for the library that is being
used.
- The returned message is terminated with a trailing zero, and the func-
- tion returns the number of code units used, excluding the trailing
+ The returned message is terminated with a trailing zero, and the func-
+ tion returns the number of code units used, excluding the trailing
zero. If the error number is unknown, the negative error code PCRE2_ER-
- ROR_BADDATA is returned. If the buffer is too small, the message is
+ ROR_BADDATA is returned. If the buffer is too small, the message is
truncated (but still with a trailing zero), and the negative error code
- PCRE2_ERROR_NOMEMORY is returned. None of the messages are very long;
+ PCRE2_ERROR_NOMEMORY is returned. None of the messages are very long;
a buffer size of 120 code units is ample.
@@ -3005,39 +3006,39 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- Captured substrings can be accessed directly by using the ovector as
+ Captured substrings can be accessed directly by using the ovector as
described above. For convenience, auxiliary functions are provided for
- extracting captured substrings as new, separate, zero-terminated
+ extracting captured substrings as new, separate, zero-terminated
strings. A substring that contains a binary zero is correctly extracted
- and has a further zero added on the end, but the result is not, of
+ and has a further zero added on the end, but the result is not, of
course, a C string.
The functions in this section identify substrings by number. The number
zero refers to the entire matched substring, with higher numbers refer-
- ring to substrings captured by parenthesized groups. After a partial
- match, only substring zero is available. An attempt to extract any
- other substring gives the error PCRE2_ERROR_PARTIAL. The next section
+ ring to substrings captured by parenthesized groups. After a partial
+ match, only substring zero is available. An attempt to extract any
+ other substring gives the error PCRE2_ERROR_PARTIAL. The next section
describes similar functions for extracting captured substrings by name.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
- "ab", the start and end offset values for the match are 2 and 0. In
- this situation, calling these functions with a zero substring number
+ the match. For example, if the pattern (?=ab\K) is matched against
+ "ab", the start and end offset values for the match are 2 and 0. In
+ this situation, calling these functions with a zero substring number
extracts a zero-length empty string.
- You can find the length in code units of a captured substring without
- extracting it by calling pcre2_substring_length_bynumber(). The first
- argument is a pointer to the match data block, the second is the group
- number, and the third is a pointer to a variable into which the length
- is placed. If you just want to know whether or not the substring has
+ You can find the length in code units of a captured substring without
+ extracting it by calling pcre2_substring_length_bynumber(). The first
+ argument is a pointer to the match data block, the second is the group
+ number, and the third is a pointer to a variable into which the length
+ is placed. If you just want to know whether or not the substring has
been captured, you can pass the third argument as NULL.
- The pcre2_substring_copy_bynumber() function copies a captured sub-
- string into a supplied buffer, whereas pcre2_substring_get_bynumber()
- copies it into new memory, obtained using the same memory allocation
- function that was used for the match data block. The first two argu-
- ments of these functions are a pointer to the match data block and a
+ The pcre2_substring_copy_bynumber() function copies a captured sub-
+ string into a supplied buffer, whereas pcre2_substring_get_bynumber()
+ copies it into new memory, obtained using the same memory allocation
+ function that was used for the match data block. The first two argu-
+ ments of these functions are a pointer to the match data block and a
capture group number.
The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -3046,25 +3047,25 @@
for the extracted substring, excluding the terminating zero.
For pcre2_substring_get_bynumber() the third and fourth arguments point
- to variables that are updated with a pointer to the new memory and the
- number of code units that comprise the substring, again excluding the
- terminating zero. When the substring is no longer needed, the memory
+ to variables that are updated with a pointer to the new memory and the
+ number of code units that comprise the substring, again excluding the
+ terminating zero. When the substring is no longer needed, the memory
should be freed by calling pcre2_substring_free().
- The return value from all these functions is zero for success, or a
- negative error code. If the pattern match failed, the match failure
- code is returned. If a substring number greater than zero is used af-
- ter a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
+ The return value from all these functions is zero for success, or a
+ negative error code. If the pattern match failed, the match failure
+ code is returned. If a substring number greater than zero is used af-
+ ter a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
error codes are:
PCRE2_ERROR_NOMEMORY
- The buffer was too small for pcre2_substring_copy_bynumber(), or the
+ The buffer was too small for pcre2_substring_copy_bynumber(), or the
attempt to get memory failed for pcre2_substring_get_bynumber().
PCRE2_ERROR_NOSUBSTRING
- There is no substring with that number in the pattern, that is, the
+ There is no substring with that number in the pattern, that is, the
number is greater than the number of capturing parentheses.
PCRE2_ERROR_UNAVAILABLE
@@ -3075,8 +3076,8 @@
PCRE2_ERROR_UNSET
- The substring did not participate in the match. For example, if the
- pattern is (abc)|(def) and the subject is "def", and the ovector con-
+ The substring did not participate in the match. For example, if the
+ pattern is (abc)|(def) and the subject is "def", and the ovector con-
tains at least two capturing slots, substring number 1 is unset.
@@ -3087,31 +3088,31 @@
void pcre2_substring_list_free(PCRE2_SPTR *list);
- The pcre2_substring_list_get() function extracts all available sub-
- strings and builds a list of pointers to them. It also (optionally)
- builds a second list that contains their lengths (in code units), ex-
- cluding a terminating zero that is added to each of them. All this is
+ The pcre2_substring_list_get() function extracts all available sub-
+ strings and builds a list of pointers to them. It also (optionally)
+ builds a second list that contains their lengths (in code units), ex-
+ cluding a terminating zero that is added to each of them. All this is
done in a single block of memory that is obtained using the same memory
allocation function that was used to get the match data block.
- This function must be called only after a successful match. If called
+ This function must be called only after a successful match. If called
after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.
- The address of the memory block is returned via listptr, which is also
+ The address of the memory block is returned via listptr, which is also
the start of the list of string pointers. The end of the list is marked
- by a NULL pointer. The address of the list of lengths is returned via
- lengthsptr. If your strings do not contain binary zeros and you do not
+ by a NULL pointer. The address of the list of lengths is returned via
+ lengthsptr. If your strings do not contain binary zeros and you do not
therefore need the lengths, you may supply NULL as the lengthsptr argu-
- ment to disable the creation of a list of lengths. The yield of the
- function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
- ory block could not be obtained. When the list is no longer needed, it
+ ment to disable the creation of a list of lengths. The yield of the
+ function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
+ ory block could not be obtained. When the list is no longer needed, it
should be freed by calling pcre2_substring_list_free().
If this function encounters a substring that is unset, which can happen
- when capture group number n+1 matches some part of the subject, but
- group n has not been used at all, it returns an empty string. This can
+ when capture group number n+1 matches some part of the subject, but
+ group n has not been used at all, it returns an empty string. This can
be distinguished from a genuine zero-length substring by inspecting the
- appropriate offset in the ovector, which contain PCRE2_UNSET for unset
+ appropriate offset in the ovector, which contain PCRE2_UNSET for unset
substrings, or by calling pcre2_substring_length_bynumber().
@@ -3131,7 +3132,7 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- To extract a substring by name, you first have to find associated num-
+ To extract a substring by name, you first have to find associated num-
ber. For example, for this pattern:
(a+)b(?<xxx>\d+)...
@@ -3139,32 +3140,32 @@
the number of the capture group called "xxx" is 2. If the name is known
to be unique (PCRE2_DUPNAMES was not set), you can find the number from
the name by calling pcre2_substring_number_from_name(). The first argu-
- ment is the compiled pattern, and the second is the name. The yield of
- the function is the group number, PCRE2_ERROR_NOSUBSTRING if there is
- no group with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if there is
- more than one group with that name. Given the number, you can extract
- the substring directly from the ovector, or use one of the "bynumber"
+ ment is the compiled pattern, and the second is the name. The yield of
+ the function is the group number, PCRE2_ERROR_NOSUBSTRING if there is
+ no group with that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if there is
+ more than one group with that name. Given the number, you can extract
+ the substring directly from the ovector, or use one of the "bynumber"
functions described above.
- For convenience, there are also "byname" functions that correspond to
+ For convenience, there are also "byname" functions that correspond to
the "bynumber" functions, the only difference being that the second ar-
- gument is a name instead of a number. If PCRE2_DUPNAMES is set and
+ gument is a name instead of a number. If PCRE2_DUPNAMES is set and
there are duplicate names, these functions scan all the groups with the
- given name, and return the captured substring from the first named
+ given name, and return the captured substring from the first named
group that is set.
- If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
- returned. If all groups with the name have numbers that are greater
+ If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
+ returned. If all groups with the name have numbers that are greater
than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is re-
- turned. If there is at least one group with a slot in the ovector, but
+ turned. If there is at least one group with a slot in the ovector, but
no group is found to be set, PCRE2_ERROR_UNSET is returned.
Warning: If the pattern uses the (?| feature to set up multiple capture
- groups with the same number, as described in the section on duplicate
+ groups with the same number, as described in the section on duplicate
group numbers in the pcre2pattern page, you cannot use names to distin-
- guish the different capture groups, because names are not included in
- the compiled code. The matching process uses only numbers. For this
- reason, the use of different names for groups with the same number
+ guish the different capture groups, because names are not included in
+ the compiled code. The matching process uses only numbers. For this
+ reason, the use of different names for groups with the same number
causes an error at compile time.
@@ -3177,54 +3178,54 @@
PCRE2_SIZE rlength, PCRE2_UCHAR *outputbuffer,
PCRE2_SIZE *outlengthptr);
- This function calls pcre2_match() and then makes a copy of the subject
- string in outputbuffer, replacing one or more parts that were matched
+ This function calls pcre2_match() and then makes a copy of the subject
+ string in outputbuffer, replacing one or more parts that were matched
with the replacement string, whose length is supplied in rlength. This
- can be given as PCRE2_ZERO_TERMINATED for a zero-terminated string.
- The default is to perform just one replacement, but there is an option
- that requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL below
+ can be given as PCRE2_ZERO_TERMINATED for a zero-terminated string.
+ The default is to perform just one replacement, but there is an option
+ that requests multiple replacements (see PCRE2_SUBSTITUTE_GLOBAL below
for details).
- Matches in which a \K item in a lookahead in the pattern causes the
- match to end before it starts are not supported, and give rise to an
+ Matches in which a \K item in a lookahead in the pattern causes the
+ match to end before it starts are not supported, and give rise to an
error return. For global replacements, matches in which \K in a lookbe-
- hind causes the match to start earlier than the point that was reached
+ hind causes the match to start earlier than the point that was reached
in the previous iteration are also not supported.
- The first seven arguments of pcre2_substitute() are the same as for
+ The first seven arguments of pcre2_substitute() are the same as for
pcre2_match(), except that the partial matching options are not permit-
- ted, and match_data may be passed as NULL, in which case a match data
- block is obtained and freed within this function, using memory manage-
- ment functions from the match context, if provided, or else those that
+ ted, and match_data may be passed as NULL, in which case a match data
+ block is obtained and freed within this function, using memory manage-
+ ment functions from the match context, if provided, or else those that
were used to allocate memory for the compiled code.
- If an external match_data block is provided, its contents afterwards
- are those set by the final call to pcre2_match(). For global changes,
- this will have ended in a matching error. The contents of the ovector
+ If an external match_data block is provided, its contents afterwards
+ are those set by the final call to pcre2_match(). For global changes,
+ this will have ended in a matching error. The contents of the ovector
within the match data block may or may not have been changed.
- The outlengthptr argument must point to a variable that contains the
- length, in code units, of the output buffer. If the function is suc-
- cessful, the value is updated to contain the length of the new string,
+ The outlengthptr argument must point to a variable that contains the
+ length, in code units, of the output buffer. If the function is suc-
+ cessful, the value is updated to contain the length of the new string,
excluding the trailing zero that is automatically added.
- If the function is not successful, the value set via outlengthptr de-
- pends on the type of error. For syntax errors in the replacement
+ If the function is not successful, the value set via outlengthptr de-
+ pends on the type of error. For syntax errors in the replacement
string, the value is the offset in the replacement string where the er-
- ror was detected. For other errors, the value is PCRE2_UNSET by de-
+ ror was detected. For other errors, the value is PCRE2_UNSET by de-
fault. This includes the case of the output buffer being too small, un-
less PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which case
- the value is the minimum length needed, including space for the trail-
+ the value is the minimum length needed, including space for the trail-
ing zero. Note that in order to compute the required length, pcre2_sub-
stitute() has to simulate all the matching and copying, instead of giv-
ing an error return as soon as the buffer overflows. Note also that the
length is in code units, not bytes.
- In the replacement string, which is interpreted as a UTF string in UTF
+ In the replacement string, which is interpreted as a UTF string in UTF
mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK op-
tion is set, a dollar character is an escape character that can specify
- the insertion of characters from capture groups or names from (*MARK)
- or other control verbs in the pattern. The following forms are always
+ the insertion of characters from capture groups or names from (*MARK)
+ or other control verbs in the pattern. The following forms are always
recognized:
$$ insert a dollar character
@@ -3231,18 +3232,18 @@
$<n> or ${<n>} insert the contents of group <n>
$*MARK or ${*MARK} insert a control verb name
- Either a group number or a group name can be given for <n>. Curly
- brackets are required only if the following character would be inter-
+ Either a group number or a group name can be given for <n>. Curly
+ brackets are required only if the following character would be inter-
preted as part of the number or name. The number may be zero to include
- the entire matched string. For example, if the pattern a(b)c is
- matched with "=abc=" and the replacement string "+$1$0$1+", the result
+ the entire matched string. For example, if the pattern a(b)c is
+ matched with "=abc=" and the replacement string "+$1$0$1+", the result
is "=+babcb+=".
- $*MARK inserts the name from the last encountered backtracking control
- verb on the matching path that has a name. (*MARK) must always include
- a name, but the other verbs need not. For example, in the case of
+ $*MARK inserts the name from the last encountered backtracking control
+ verb on the matching path that has a name. (*MARK) must always include
+ a name, but the other verbs need not. For example, in the case of
(*MARK:A)(*PRUNE) the name inserted is "A", but for (*MARK:A)(*PRUNE:B)
- the relevant name is "B". This facility can be used to perform simple
+ the relevant name is "B". This facility can be used to perform simple
simultaneous substitutions, as this pcre2test example shows:
/(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
@@ -3249,19 +3250,19 @@
apple lemon
2: pear orange
- As well as the usual options for pcre2_match(), a number of additional
+ As well as the usual options for pcre2_match(), a number of additional
options can be set in the options argument of pcre2_substitute().
PCRE2_SUBSTITUTE_GLOBAL causes the function to iterate over the subject
- string, replacing every matching substring. If this option is not set,
- only the first matching substring is replaced. The search for matches
- takes place in the original subject string (that is, previous replace-
- ments do not affect it). Iteration is implemented by advancing the
- startoffset value for each search, which is always passed the entire
+ string, replacing every matching substring. If this option is not set,
+ only the first matching substring is replaced. The search for matches
+ takes place in the original subject string (that is, previous replace-
+ ments do not affect it). Iteration is implemented by advancing the
+ startoffset value for each search, which is always passed the entire
subject string. If an offset limit is set in the match context, search-
ing stops when that limit is reached.
- You can restrict the effect of a global substitution to a portion of
+ You can restrict the effect of a global substitution to a portion of
the subject string by setting either or both of startoffset and an off-
set limit. Here is a pcre2test example:
@@ -3269,87 +3270,87 @@
ABC ABC ABC ABC\=offset=3,offset_limit=12
2: ABC A!C A!C ABC
- When continuing with global substitutions after matching a substring
+ When continuing with global substitutions after matching a substring
with zero length, an attempt to find a non-empty match at the same off-
set is performed. If this is not successful, the offset is advanced by
one character except when CRLF is a valid newline sequence and the next
- two characters are CR, LF. In this case, the offset is advanced by two
+ two characters are CR, LF. In this case, the offset is advanced by two
characters.
- PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
+ PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
- ORY immediately. If this option is set, however, pcre2_substitute()
+ ORY immediately. If this option is set, however, pcre2_substitute()
continues to go through the motions of matching and substituting (with-
- out, of course, writing anything) in order to compute the size of buf-
- fer that is needed. This value is passed back via the outlengthptr
- variable, with the result of the function still being PCRE2_ER-
+ out, of course, writing anything) in order to compute the size of buf-
+ fer that is needed. This value is passed back via the outlengthptr
+ variable, with the result of the function still being PCRE2_ER-
ROR_NOMEMORY.
- Passing a buffer size of zero is a permitted way of finding out how
- much memory is needed for given substitution. However, this does mean
+ Passing a buffer size of zero is a permitted way of finding out how
+ much memory is needed for given substitution. However, this does mean
that the entire operation is carried out twice. Depending on the appli-
- cation, it may be more efficient to allocate a large buffer and free
- the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
+ cation, it may be more efficient to allocate a large buffer and free
+ the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
FLOW_LENGTH.
PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capture groups that
do not appear in the pattern to be treated as unset groups. This option
- should be used with care, because it means that a typo in a group name
+ should be used with care, because it means that a typo in a group name
or number no longer causes the PCRE2_ERROR_NOSUBSTRING error.
PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capture groups (including un-
- known groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be treated
- as empty strings when inserted as described above. If this option is
+ known groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be treated
+ as empty strings when inserted as described above. If this option is
not set, an attempt to insert an unset group causes the PCRE2_ERROR_UN-
- SET error. This option does not influence the extended substitution
+ SET error. This option does not influence the extended substitution
syntax described below.
- PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
- replacement string. Without this option, only the dollar character is
- special, and only the group insertion forms listed above are valid.
+ PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
+ replacement string. Without this option, only the dollar character is
+ special, and only the group insertion forms listed above are valid.
When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:
- Firstly, backslash in a replacement string is interpreted as an escape
+ Firstly, backslash in a replacement string is interpreted as an escape
character. The usual forms such as \n or \x{ddd} can be used to specify
- particular character codes, and backslash followed by any non-alphanu-
- meric character quotes that character. Extended quoting can be coded
+ particular character codes, and backslash followed by any non-alphanu-
+ meric character quotes that character. Extended quoting can be coded
using \Q...\E, exactly as in pattern strings.
- There are also four escape sequences for forcing the case of inserted
- letters. The insertion mechanism has three states: no case forcing,
+ There are also four escape sequences for forcing the case of inserted
+ letters. The insertion mechanism has three states: no case forcing,
force upper case, and force lower case. The escape sequences change the
current state: \U and \L change to upper or lower case forcing, respec-
- tively, and \E (when not terminating a \Q quoted sequence) reverts to
- no case forcing. The sequences \u and \l force the next character (if
- it is a letter) to upper or lower case, respectively, and then the
+ tively, and \E (when not terminating a \Q quoted sequence) reverts to
+ no case forcing. The sequences \u and \l force the next character (if
+ it is a letter) to upper or lower case, respectively, and then the
state automatically reverts to no case forcing. Case forcing applies to
- all inserted characters, including those from capture groups and let-
+ all inserted characters, including those from capture groups and let-
ters within \Q...\E quoted sequences.
Note that case forcing sequences such as \U...\E do not nest. For exam-
- ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
- \E has no effect. Note also that the PCRE2_ALT_BSUX and PCRE2_EX-
+ ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
+ \E has no effect. Note also that the PCRE2_ALT_BSUX and PCRE2_EX-
TRA_ALT_BSUX options do not apply to not apply to replacement strings.
- The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
- flexibility to capture group substitution. The syntax is similar to
+ The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
+ flexibility to capture group substitution. The syntax is similar to
that used by Bash:
${<n>:-<string>}
${<n>:+<string1>:<string2>}
- As before, <n> may be a group number or a name. The first form speci-
- fies a default value. If group <n> is set, its value is inserted; if
- not, <string> is expanded and the result inserted. The second form
- specifies strings that are expanded and inserted when group <n> is set
- or unset, respectively. The first form is just a convenient shorthand
+ As before, <n> may be a group number or a name. The first form speci-
+ fies a default value. If group <n> is set, its value is inserted; if
+ not, <string> is expanded and the result inserted. The second form
+ specifies strings that are expanded and inserted when group <n> is set
+ or unset, respectively. The first form is just a convenient shorthand
for
${<n>:+${<n>}:<string>}
- Backslash can be used to escape colons and closing curly brackets in
- the replacement strings. A change of the case forcing state within a
- replacement string remains in force afterwards, as shown in this
+ Backslash can be used to escape colons and closing curly brackets in
+ the replacement strings. A change of the case forcing state within a
+ replacement string remains in force afterwards, as shown in this
pcre2test example:
/(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@@ -3358,16 +3359,16 @@
somebody
1: HELLO
- The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
- substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause un-
+ The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
+ substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause un-
known groups in the extended syntax forms to be treated as unset.
- If successful, pcre2_substitute() returns the number of successful
- matches. This may be zero if no matches were found, and is never
+ If successful, pcre2_substitute() returns the number of successful
+ matches. This may be zero if no matches were found, and is never
greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set.
In the event of an error, a negative error code is returned. Except for
- PCRE2_ERROR_NOMATCH (which is never returned), errors from
+ PCRE2_ERROR_NOMATCH (which is never returned), errors from
pcre2_match() are passed straight back.
PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser-
@@ -3374,26 +3375,26 @@
tion, unless PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set.
PCRE2_ERROR_UNSET is returned for an unset substring insertion (includ-
- ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
- when the simple (non-extended) syntax is used and PCRE2_SUBSTITUTE_UN-
+ ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
+ when the simple (non-extended) syntax is used and PCRE2_SUBSTITUTE_UN-
SET_EMPTY is not set.
- PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
+ PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
- of buffer that is needed is returned via outlengthptr. Note that this
+ of buffer that is needed is returned via outlengthptr. Note that this
does not happen by default.
- PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
- the replacement string, with more particular errors being PCRE2_ER-
+ PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
+ the replacement string, with more particular errors being PCRE2_ER-
ROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REPMISSINGBRACE
- (closing curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION (syntax
- error in extended group substitution), and PCRE2_ERROR_BADSUBSPATTERN
+ (closing curly bracket not found), PCRE2_ERROR_BADSUBSTITUTION (syntax
+ error in extended group substitution), and PCRE2_ERROR_BADSUBSPATTERN
(the pattern match ended before it started or the match started earlier
- than the current position in the subject, which can happen if \K is
+ than the current position in the subject, which can happen if \K is
used in an assertion).
As for all PCRE2 errors, a text message that describes the error can be
- obtained by calling the pcre2_get_error_message() function (see "Ob-
+ obtained by calling the pcre2_get_error_message() function (see "Ob-
taining a textual error message" above).
Substitution callouts
@@ -3402,15 +3403,15 @@
int (*callout_function)(pcre2_substitute_callout_block *, void *),
void *callout_data);
- The pcre2_set_substitution_callout() function can be used to specify a
- callout function for pcre2_substitute(). This information is passed in
+ The pcre2_set_substitution_callout() function can be used to specify a
+ callout function for pcre2_substitute(). This information is passed in
a match context. The callout function is called after each substitution
has been processed, but it can cause the replacement not to happen. The
- callout function is not called for simulated substitutions that happen
+ callout function is not called for simulated substitutions that happen
as a result of the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option.
The first argument of the callout function is a pointer to a substitute
- callout block structure, which contains the following fields, not nec-
+ callout block structure, which contains the following fields, not nec-
essarily in this order:
uint32_t version;
@@ -3421,9 +3422,9 @@
uint32_t oveccount;
PCRE2_SIZE output_offsets[2];
- The version field contains the version number of the block format. The
- current version is 0. The version number will increase in future if
- more fields are added, but the intention is never to remove any of the
+ The version field contains the version number of the block format. The
+ current version is 0. The version number will increase in future if
+ more fields are added, but the intention is never to remove any of the
existing fields.
The subscount field is the number of the current match. It is 1 for the
@@ -3430,25 +3431,25 @@
first callout, 2 for the second, and so on. The input and output point-
ers are copies of the values passed to pcre2_substitute().
- The ovector field points to the ovector, which contains the result of
+ The ovector field points to the ovector, which contains the result of
the most recent match. The oveccount field contains the number of pairs
that are set in the ovector, and is always greater than zero.
- The output_offsets vector contains the offsets of the replacement in
- the output string. This has already been processed for dollar and (if
+ The output_offsets vector contains the offsets of the replacement in
+ the output string. This has already been processed for dollar and (if
requested) backslash substitutions as described above.
- The second argument of the callout function is the value passed as
- callout_data when the function was registered. The value returned by
+ The second argument of the callout function is the value passed as
+ callout_data when the function was registered. The value returned by
the callout function is interpreted as follows:
- If the value is zero, the replacement is accepted, and, if PCRE2_SUB-
- STITUTE_GLOBAL is set, processing continues with a search for the next
- match. If the value is not zero, the current replacement is not ac-
- cepted. If the value is greater than zero, processing continues when
- PCRE2_SUBSTITUTE_GLOBAL is set. Otherwise (the value is less than zero
- or PCRE2_SUBSTITUTE_GLOBAL is not set), the the rest of the input is
- copied to the output and the call to pcre2_substitute() exits, return-
+ If the value is zero, the replacement is accepted, and, if PCRE2_SUB-
+ STITUTE_GLOBAL is set, processing continues with a search for the next
+ match. If the value is not zero, the current replacement is not ac-
+ cepted. If the value is greater than zero, processing continues when
+ PCRE2_SUBSTITUTE_GLOBAL is set. Otherwise (the value is less than zero
+ or PCRE2_SUBSTITUTE_GLOBAL is not set), the the rest of the input is
+ copied to the output and the call to pcre2_substitute() exits, return-
ing the number of matches so far.
@@ -3457,56 +3458,56 @@
int pcre2_substring_nametable_scan(const pcre2_code *code,
PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last);
- When a pattern is compiled with the PCRE2_DUPNAMES option, names for
- capture groups are not required to be unique. Duplicate names are al-
- ways allowed for groups with the same number, created by using the (?|
+ When a pattern is compiled with the PCRE2_DUPNAMES option, names for
+ capture groups are not required to be unique. Duplicate names are al-
+ ways allowed for groups with the same number, created by using the (?|
feature. Indeed, if such groups are named, they are required to use the
same names.
- Normally, patterns that use duplicate names are such that in any one
- match, only one of each set of identically-named groups participates.
+ Normally, patterns that use duplicate names are such that in any one
+ match, only one of each set of identically-named groups participates.
An example is shown in the pcre2pattern documentation.
- When duplicates are present, pcre2_substring_copy_byname() and
- pcre2_substring_get_byname() return the first substring corresponding
- to the given name that is set. Only if none are set is PCRE2_ERROR_UN-
- SET is returned. The pcre2_substring_number_from_name() function re-
- turns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate
+ When duplicates are present, pcre2_substring_copy_byname() and
+ pcre2_substring_get_byname() return the first substring corresponding
+ to the given name that is set. Only if none are set is PCRE2_ERROR_UN-
+ SET is returned. The pcre2_substring_number_from_name() function re-
+ turns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are duplicate
names.
- If you want to get full details of all captured substrings for a given
- name, you must use the pcre2_substring_nametable_scan() function. The
- first argument is the compiled pattern, and the second is the name. If
- the third and fourth arguments are NULL, the function returns a group
+ If you want to get full details of all captured substrings for a given
+ name, you must use the pcre2_substring_nametable_scan() function. The
+ first argument is the compiled pattern, and the second is the name. If
+ the third and fourth arguments are NULL, the function returns a group
number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise.
When the third and fourth arguments are not NULL, they must be pointers
- to variables that are updated by the function. After it has run, they
+ to variables that are updated by the function. After it has run, they
point to the first and last entries in the name-to-number table for the
- given name, and the function returns the length of each entry in code
- units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
+ given name, and the function returns the length of each entry in code
+ units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
no entries for the given name.
The format of the name table is described above in the section entitled
- Information about a pattern. Given all the relevant entries for the
- name, you can extract each of their numbers, and hence the captured
+ Information about a pattern. Given all the relevant entries for the
+ name, you can extract each of their numbers, and hence the captured
data.
FINDING ALL POSSIBLE MATCHES AT ONE POSITION
- The traditional matching function uses a similar algorithm to Perl,
- which stops when it finds the first match at a given point in the sub-
+ The traditional matching function uses a similar algorithm to Perl,
+ which stops when it finds the first match at a given point in the sub-
ject. If you want to find all possible matches, or the longest possible
- match at a given position, consider using the alternative matching
- function (see below) instead. If you cannot use the alternative func-
+ match at a given position, consider using the alternative matching
+ function (see below) instead. If you cannot use the alternative func-
tion, you can kludge it up by making use of the callout facility, which
is described in the pcre2callout documentation.
What you have to do is to insert a callout right at the end of the pat-
- tern. When your callout function is called, extract and save the cur-
- rent matched substring. Then return 1, which forces pcre2_match() to
- backtrack and try other alternatives. Ultimately, when it runs out of
+ tern. When your callout function is called, extract and save the cur-
+ rent matched substring. Then return 1, which forces pcre2_match() to
+ backtrack and try other alternatives. Ultimately, when it runs out of
matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH.
@@ -3518,26 +3519,26 @@
pcre2_match_context *mcontext,
int *workspace, PCRE2_SIZE wscount);
- The function pcre2_dfa_match() is called to match a subject string
- against a compiled pattern, using a matching algorithm that scans the
+ The function pcre2_dfa_match() is called to match a subject string
+ against a compiled pattern, using a matching algorithm that scans the
subject string just once (not counting lookaround assertions), and does
- not backtrack. This has different characteristics to the normal algo-
- rithm, and is not compatible with Perl. Some of the features of PCRE2
- patterns are not supported. Nevertheless, there are times when this
- kind of matching can be useful. For a discussion of the two matching
+ not backtrack. This has different characteristics to the normal algo-
+ rithm, and is not compatible with Perl. Some of the features of PCRE2
+ patterns are not supported. Nevertheless, there are times when this
+ kind of matching can be useful. For a discussion of the two matching
algorithms, and a list of features that pcre2_dfa_match() does not sup-
port, see the pcre2matching documentation.
- The arguments for the pcre2_dfa_match() function are the same as for
+ The arguments for the pcre2_dfa_match() function are the same as for
pcre2_match(), plus two extras. The ovector within the match data block
is used in a different way, and this is described below. The other com-
- mon arguments are used in the same way as for pcre2_match(), so their
+ mon arguments are used in the same way as for pcre2_match(), so their
description is not repeated here.
- The two additional arguments provide workspace for the function. The
- workspace vector should contain at least 20 elements. It is used for
+ The two additional arguments provide workspace for the function. The
+ workspace vector should contain at least 20 elements. It is used for
keeping track of multiple paths through the pattern tree. More
- workspace is needed for patterns and subjects where there are a lot of
+ workspace is needed for patterns and subjects where there are a lot of
potential matches.
Here is an example of a simple call to pcre2_dfa_match():
@@ -3557,45 +3558,45 @@
Option bits for pcre_dfa_match()
- The unused bits of the options argument for pcre2_dfa_match() must be
- zero. The only bits that may be set are PCRE2_ANCHORED,
- PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO-
+ The unused bits of the options argument for pcre2_dfa_match() must be
+ zero. The only bits that may be set are PCRE2_ANCHORED,
+ PCRE2_COPY_MATCHED_SUBJECT, PCRE2_ENDANCHORED, PCRE2_NOTBOL, PCRE2_NO-
TEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_UTF_CHECK,
- PCRE2_PARTIAL_HARD, PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and
- PCRE2_DFA_RESTART. All but the last four of these are exactly the same
+ PCRE2_PARTIAL_HARD, PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and
+ PCRE2_DFA_RESTART. All but the last four of these are exactly the same
as for pcre2_match(), so their description is not repeated here.
PCRE2_PARTIAL_HARD
PCRE2_PARTIAL_SOFT
- These have the same general effect as they do for pcre2_match(), but
- the details are slightly different. When PCRE2_PARTIAL_HARD is set for
- pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
+ These have the same general effect as they do for pcre2_match(), but
+ the details are slightly different. When PCRE2_PARTIAL_HARD is set for
+ pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
subject is reached and there is still at least one matching possibility
that requires additional characters. This happens even if some complete
- matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
- return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
- if the end of the subject is reached, there have been no complete
+ matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
+ return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
+ if the end of the subject is reached, there have been no complete
matches, but there is still at least one matching possibility. The por-
- tion of the string that was inspected when the longest partial match
+ tion of the string that was inspected when the longest partial match
was found is set as the first matching string in both cases. There is a
- more detailed discussion of partial and multi-segment matching, with
+ more detailed discussion of partial and multi-segment matching, with
examples, in the pcre2partial documentation.
PCRE2_DFA_SHORTEST
- Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
+ Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
stop as soon as it has found one match. Because of the way the alterna-
- tive algorithm works, this is necessarily the shortest possible match
+ tive algorithm works, this is necessarily the shortest possible match
at the first possible matching point in the subject string.
PCRE2_DFA_RESTART
- When pcre2_dfa_match() returns a partial match, it is possible to call
+ When pcre2_dfa_match() returns a partial match, it is possible to call
it again, with additional subject characters, and have it continue with
the same match. The PCRE2_DFA_RESTART option requests this action; when
- it is set, the workspace and wscount options must reference the same
- vector as before because data about the match so far is left in them
+ it is set, the workspace and wscount options must reference the same
+ vector as before because data about the match so far is left in them
after a partial match. There is more discussion of this facility in the
pcre2partial documentation.
@@ -3603,8 +3604,8 @@
When pcre2_dfa_match() succeeds, it may have matched more than one sub-
string in the subject. Note, however, that all the matches from one run
- of the function start at the same point in the subject. The shorter
- matches are all initial substrings of the longer matches. For example,
+ of the function start at the same point in the subject. The shorter
+ matches are all initial substrings of the longer matches. For example,
if the pattern
<.*>
@@ -3619,80 +3620,80 @@
<something> <something else>
<something>
- On success, the yield of the function is a number greater than zero,
- which is the number of matched substrings. The offsets of the sub-
- strings are returned in the ovector, and can be extracted by number in
- the same way as for pcre2_match(), but the numbers bear no relation to
- any capture groups that may exist in the pattern, because DFA matching
+ On success, the yield of the function is a number greater than zero,
+ which is the number of matched substrings. The offsets of the sub-
+ strings are returned in the ovector, and can be extracted by number in
+ the same way as for pcre2_match(), but the numbers bear no relation to
+ any capture groups that may exist in the pattern, because DFA matching
does not support capturing.
- Calls to the convenience functions that extract substrings by name re-
+ Calls to the convenience functions that extract substrings by name re-
turn the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used af-
- ter a DFA match. The convenience functions that extract substrings by
+ ter a DFA match. The convenience functions that extract substrings by
number never return PCRE2_ERROR_NOSUBSTRING.
- The matched strings are stored in the ovector in reverse order of
- length; that is, the longest matching string is first. If there were
- too many matches to fit into the ovector, the yield of the function is
+ The matched strings are stored in the ovector in reverse order of
+ length; that is, the longest matching string is first. If there were
+ too many matches to fit into the ovector, the yield of the function is
zero, and the vector is filled with the longest matches.
- NOTE: PCRE2's "auto-possessification" optimization usually applies to
- character repeats at the end of a pattern (as well as internally). For
- example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
- matching, this means that only one possible match is found. If you re-
+ NOTE: PCRE2's "auto-possessification" optimization usually applies to
+ character repeats at the end of a pattern (as well as internally). For
+ example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
+ matching, this means that only one possible match is found. If you re-
ally do want multiple matches in such cases, either use an ungreedy re-
- peat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when com-
+ peat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when com-
piling.
Error returns from pcre2_dfa_match()
The pcre2_dfa_match() function returns a negative number when it fails.
- Many of the errors are the same as for pcre2_match(), as described
+ Many of the errors are the same as for pcre2_match(), as described
above. There are in addition the following errors that are specific to
pcre2_dfa_match():
PCRE2_ERROR_DFA_UITEM
- This return is given if pcre2_dfa_match() encounters an item in the
- pattern that it does not support, for instance, the use of \C in a UTF
+ This return is given if pcre2_dfa_match() encounters an item in the
+ pattern that it does not support, for instance, the use of \C in a UTF
mode or a backreference.
PCRE2_ERROR_DFA_UCOND
- This return is given if pcre2_dfa_match() encounters a condition item
+ This return is given if pcre2_dfa_match() encounters a condition item
that uses a backreference for the condition, or a test for recursion in
a specific capture group. These are not supported.
PCRE2_ERROR_DFA_UINVALID_UTF
- This return is given if pcre2_dfa_match() is called for a pattern that
- was compiled with PCRE2_MATCH_INVALID_UTF. This is not supported for
+ This return is given if pcre2_dfa_match() is called for a pattern that
+ was compiled with PCRE2_MATCH_INVALID_UTF. This is not supported for
DFA matching.
PCRE2_ERROR_DFA_WSSIZE
- This return is given if pcre2_dfa_match() runs out of space in the
+ This return is given if pcre2_dfa_match() runs out of space in the
workspace vector.
PCRE2_ERROR_DFA_RECURSE
When a recursion or subroutine call is processed, the matching function
- calls itself recursively, using private memory for the ovector and
- workspace. This error is given if the internal ovector is not large
- enough. This should be extremely rare, as a vector of size 1000 is
+ calls itself recursively, using private memory for the ovector and
+ workspace. This error is given if the internal ovector is not large
+ enough. This should be extremely rare, as a vector of size 1000 is
used.
PCRE2_ERROR_DFA_BADRESTART
- When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
- some plausibility checks are made on the contents of the workspace,
- which should contain data about the previous partial match. If any of
+ When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
+ some plausibility checks are made on the contents of the workspace,
+ which should contain data about the previous partial match. If any of
these checks fail, this error is given.
SEE ALSO
- pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
+ pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3).
@@ -3705,7 +3706,7 @@
REVISION
- Last updated: 20 July 2019
+ Last updated: 22 July 2019
Copyright (c) 1997-2019 University of Cambridge.
------------------------------------------------------------------------------
@@ -5703,13 +5704,15 @@
the subject string is reached successfully, but matching cannot con-
tinue because more characters are needed, and in addition, either at
least one character in the subject has been inspected or the pattern
- contains a lookbehind. An inspected character need not form part of the
- final matched string; lookbehind assertions and the \K escape sequence
- provide ways of inspecting characters before the start of a matched
- string.
+ contains a lookbehind, or (when PCRE2_PARTIAL_HARD is set) the pattern
+ could match an empty string. An inspected character need not form part
+ of the final matched string; lookbehind assertions and the \K escape
+ sequence provide ways of inspecting characters before the start of a
+ matched string.
- The two additional requirements define the cases where adding more
- characters to the existing subject may complete the match. Without
+ The three additional requirements define the cases where adding more
+ characters to the existing subject may complete the same match that
+ would occur if they had all been present in the first place. Without
these conditions there would be a partial match of an empty string at
the end of the subject for all unanchored patterns (and also for an-
chored patterns if the subject itself is empty).
@@ -6068,7 +6071,7 @@
REVISION
- Last updated: 21 July 2019
+ Last updated: 22 July 2019
Copyright (c) 1997-2019 University of Cambridge.
------------------------------------------------------------------------------
Modified: code/trunk/doc/pcre2api.3
===================================================================
--- code/trunk/doc/pcre2api.3 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/pcre2api.3 2019-07-22 16:30:44 UTC (rev 1142)
@@ -2720,7 +2720,8 @@
These options turn on the partial matching feature. A partial match occurs if
the end of the subject string is reached successfully, but there are not enough
subject characters to complete the match. In addition, either at least one
-character must have been inspected or the pattern must contain a lookbehind.
+character must have been inspected or the pattern must contain a lookbehind, or
+the pattern must be one that could match an empty string.
.P
If this situation arises when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD)
is set, matching continues by testing any remaining alternatives. Only if no
Modified: code/trunk/doc/pcre2partial.3
===================================================================
--- code/trunk/doc/pcre2partial.3 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/doc/pcre2partial.3 2019-07-22 16:30:44 UTC (rev 1142)
@@ -1,4 +1,4 @@
-.TH PCRE2PARTIAL 3 "21 July 2019" "PCRE2 10.34"
+.TH PCRE2PARTIAL 3 "22 July 2019" "PCRE2 10.34"
.SH NAME
PCRE2 - Perl-compatible regular expressions
.SH "PARTIAL MATCHING IN PCRE2"
@@ -56,15 +56,17 @@
A partial match occurs during a call to \fBpcre2_match()\fP when the end of the
subject string is reached successfully, but matching cannot continue because
more characters are needed, and in addition, either at least one character in
-the subject has been inspected or the pattern contains a lookbehind. An
+the subject has been inspected or the pattern contains a lookbehind, or (when
+PCRE2_PARTIAL_HARD is set) the pattern could match an empty string. An
inspected character need not form part of the final matched string; lookbehind
assertions and the \eK escape sequence provide ways of inspecting characters
before the start of a matched string.
.P
-The two additional requirements define the cases where adding more characters
-to the existing subject may complete the match. Without these conditions there
-would be a partial match of an empty string at the end of the subject for all
-unanchored patterns (and also for anchored patterns if the subject itself is
+The three additional requirements define the cases where adding more characters
+to the existing subject may complete the same match that would occur if they
+had all been present in the first place. Without these conditions there would
+be a partial match of an empty string at the end of the subject for all
+unanchored patterns (and also for anchored patterns if the subject itself is
empty).
.P
When a partial match is returned, the first two elements in the ovector point
@@ -422,6 +424,6 @@
.rs
.sp
.nf
-Last updated: 21 July 2019
+Last updated: 22 July 2019
Copyright (c) 1997-2019 University of Cambridge.
.fi
Modified: code/trunk/src/pcre2_dfa_match.c
===================================================================
--- code/trunk/src/pcre2_dfa_match.c 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/src/pcre2_dfa_match.c 2019-07-22 16:30:44 UTC (rev 1142)
@@ -3185,8 +3185,8 @@
ptr >= end_subject && /* End of subject and */
( /* either */
ptr > mb->start_used_ptr || /* Inspected non-empty string */
- mb->haslookbehind /* or pattern has lookbehind */
- )
+ mb->allowemptypartial /* or pattern has lookbehind */
+ ) /* or could match empty */
)
))
match_count = PCRE2_ERROR_PARTIAL;
@@ -3417,7 +3417,8 @@
mb->start_subject = subject;
mb->end_subject = end_subject;
mb->start_offset = start_offset;
-mb->haslookbehind = (re->max_lookbehind > 0);
+mb->allowemptypartial = (re->max_lookbehind > 0) ||
+ (re->flags & PCRE2_MATCH_EMPTY) != 0;
mb->moptions = options;
mb->poptions = re->overall_options;
mb->match_call_count = 0;
Modified: code/trunk/src/pcre2_intmodedep.h
===================================================================
--- code/trunk/src/pcre2_intmodedep.h 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/src/pcre2_intmodedep.h 2019-07-22 16:30:44 UTC (rev 1142)
@@ -854,7 +854,7 @@
uint32_t match_call_count; /* Number of times a new frame is created */
BOOL hitend; /* Hit the end of the subject at some point */
BOOL hasthen; /* Pattern contains (*THEN) */
- BOOL haslookbehind; /* Pattern contains sigificant lookbehind */
+ BOOL allowemptypartial; /* Allow empty hard partial */
const uint8_t *lcc; /* Points to lower casing table */
const uint8_t *fcc; /* Points to case-flipping table */
const uint8_t *ctypes; /* Points to table of type maps */
@@ -910,7 +910,7 @@
uint32_t poptions; /* Pattern options */
uint32_t nltype; /* Newline type */
uint32_t nllen; /* Newline string length */
- BOOL haslookbehind; /* Pattern contains significant lookbehind */
+ BOOL allowemptypartial; /* Allow empty hard partial */
PCRE2_UCHAR nl[4]; /* Newline string when fixed */
uint16_t bsr_convention; /* \R interpretation */
pcre2_callout_block *cb; /* Points to a callout block */
Modified: code/trunk/src/pcre2_match.c
===================================================================
--- code/trunk/src/pcre2_match.c 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/src/pcre2_match.c 2019-07-22 16:30:44 UTC (rev 1142)
@@ -508,7 +508,8 @@
}
#define SCHECK_PARTIAL()\
- if (mb->partial != 0 && (Feptr > mb->start_used_ptr || mb->haslookbehind)) \
+ if (mb->partial != 0 && \
+ (Feptr > mb->start_used_ptr || mb->allowemptypartial)) \
{ \
mb->hitend = TRUE; \
if (mb->partial > 1) return PCRE2_ERROR_PARTIAL; \
@@ -6451,7 +6452,8 @@
mb->start_offset = start_offset;
mb->end_subject = end_subject;
mb->hasthen = (re->flags & PCRE2_HASTHEN) != 0;
-mb->haslookbehind = (re->max_lookbehind > 0);
+mb->allowemptypartial = (re->max_lookbehind > 0) ||
+ (re->flags & PCRE2_MATCH_EMPTY) != 0;
mb->poptions = re->overall_options; /* Pattern options */
mb->ignore_skip_arg = 0;
mb->mark = mb->nomatch_mark = NULL; /* In case never set */
Modified: code/trunk/testdata/testinput2
===================================================================
--- code/trunk/testdata/testinput2 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testinput2 2019-07-22 16:30:44 UTC (rev 1142)
@@ -5719,4 +5719,10 @@
abc\n\=ph,no_jit
abc\n\=ps
+/(?![ab]).*/
+ ab\=ph,no_jit
+
+/c*+/
+ ab\=ph,offset=2,no_jit
+
# End of testinput2
Modified: code/trunk/testdata/testinput6
===================================================================
--- code/trunk/testdata/testinput6 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testinput6 2019-07-22 16:30:44 UTC (rev 1142)
@@ -5020,4 +5020,10 @@
bxyz
xyz
+/(?![ab]).*/
+ ab\=ph
+
+/c*+/
+ ab\=ph,offset=2
+
# End of testinput6
Modified: code/trunk/testdata/testoutput2
===================================================================
--- code/trunk/testdata/testoutput2 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testoutput2 2019-07-22 16:30:44 UTC (rev 1142)
@@ -17231,6 +17231,14 @@
abc\n\=ps
0:
+/(?![ab]).*/
+ ab\=ph,no_jit
+Partial match:
+
+/c*+/
+ ab\=ph,offset=2,no_jit
+Partial match:
+
# End of testinput2
Error -70: PCRE2_ERROR_BADDATA (unknown error number)
Error -62: bad serialized data
Modified: code/trunk/testdata/testoutput6
===================================================================
--- code/trunk/testdata/testoutput6 2019-07-22 11:05:19 UTC (rev 1141)
+++ code/trunk/testdata/testoutput6 2019-07-22 16:30:44 UTC (rev 1142)
@@ -7887,4 +7887,12 @@
xyz
0:
+/(?![ab]).*/
+ ab\=ph
+Partial match:
+
+/c*+/
+ ab\=ph,offset=2
+Partial match:
+
# End of testinput6
