Revision: 977
http://www.exim.org/viewvc/pcre2?view=rev&revision=977
Author: ph10
Date: 2018-08-03 10:38:36 +0100 (Fri, 03 Aug 2018)
Log Message:
-----------
Make /x more Perl-compatible by recognizing all of Unicode's "Pattern White
Space" characters, not just the ASCII ones.
Modified Paths:
--------------
code/trunk/ChangeLog
code/trunk/doc/html/pcre2api.html
code/trunk/doc/html/pcre2pattern.html
code/trunk/doc/html/pcre2syntax.html
code/trunk/doc/pcre2.txt
code/trunk/doc/pcre2api.3
code/trunk/doc/pcre2pattern.3
code/trunk/doc/pcre2syntax.3
code/trunk/src/pcre2_compile.c
code/trunk/testdata/testinput1
code/trunk/testdata/testinput4
code/trunk/testdata/testinput5
code/trunk/testdata/testoutput1
code/trunk/testdata/testoutput4
code/trunk/testdata/testoutput5
Modified: code/trunk/ChangeLog
===================================================================
--- code/trunk/ChangeLog 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/ChangeLog 2018-08-03 09:38:36 UTC (rev 977)
@@ -133,6 +133,13 @@
29. Add support for \N{U+dddd}, but not in EBCDIC environments.
30. Add support for (?^) for unsetting all imnsx options.
+
+31. The PCRE2_EXTENDED (/x) option only ever discarded space characters whose
+code point was less than 256 and that were recognized by the lookup table
+generated by pcre2_maketables(), which uses isspace() to identify white space.
+Now, when Unicode support is compiled, PCRE2_EXTENDED also discards U+0085,
+U+200E, U+200F, U+2028, and U+2029, which are additional characters defined by
+Unicode as "Pattern White Space". This makes PCRE2 compatible with Perl.
Version 10.31 12-February-2018
Modified: code/trunk/doc/html/pcre2api.html
===================================================================
--- code/trunk/doc/html/pcre2api.html 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/doc/html/pcre2api.html 2018-08-03 09:38:36 UTC (rev 977)
@@ -837,10 +837,10 @@
</P>
<P>
When a pattern is compiled with the PCRE2_EXTENDED or PCRE2_EXTENDED_MORE
-option, the newline convention affects the recognition of white space and the
-end of internal comments starting with #. The value is saved with the compiled
-pattern for subsequent use by the JIT compiler and by the two interpreted
-matching functions, <i>pcre2_match()</i> and <i>pcre2_dfa_match()</i>.
+option, the newline convention affects the recognition of the end of internal
+comments starting with #. The value is saved with the compiled pattern for
+subsequent use by the JIT compiler and by the two interpreted matching
+functions, <i>pcre2_match()</i> and <i>pcre2_dfa_match()</i>.
<br>
<br>
<b>int pcre2_set_parens_nest_limit(pcre2_compile_context *<i>ccontext</i>,</b>
@@ -1424,9 +1424,9 @@
option is set, normal backslash processing is applied to verb names and only an
unescaped closing parenthesis terminates the name. A closing parenthesis can be
included in a name either as \) or between \Q and \E. If the PCRE2_EXTENDED
-or PCRE2_EXTENDED_MORE option is set, unescaped whitespace in verb names is
-skipped and #-comments are recognized in this mode, exactly as in the rest of
-the pattern.
+or PCRE2_EXTENDED_MORE option is set with PCRE2_ALT_VERBNAMES, unescaped
+whitespace in verb names is skipped and #-comments are recognized, exactly as
+in the rest of the pattern.
<pre>
PCRE2_AUTO_CALLOUT
</pre>
@@ -1510,17 +1510,38 @@
parenthesized subpatterns, nor within numerical quantifiers such as {1,3}.
Ignorable white space is permitted between an item and a following quantifier
and between a quantifier and a following + that indicates possessiveness.
+PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be changed within
+a pattern by a (?x) option setting.
</P>
<P>
-PCRE2_EXTENDED also causes characters between an unescaped # outside a
-character class and the next newline, inclusive, to be ignored, which makes it
-possible to include comments inside complicated patterns. Note that the end of
-this type of comment is a literal newline sequence in the pattern; escape
-sequences that happen to represent a newline do not count. PCRE2_EXTENDED is
-equivalent to Perl's /x option, and it can be changed within a pattern by a
-(?x) option setting.
+When PCRE2 is compiled without Unicode support, PCRE2_EXTENDED recognizes as
+white space only those characters with code points less than 256 that are
+flagged as white space in its low-character table. The table is normally
+created by
+<a href="pcre2_maketables.html"><b>pcre2_maketables()</b>,</a>
+which uses the <b>isspace()</b> function to identify space characters. In most
+ASCII environments, the relevant characters are those with code points 0x0009
+(tab), 0x000A (linefeed), 0x000B (vertical tab), 0x000C (formfeed), 0x000D
+(carriage return), and 0x0020 (space).
</P>
<P>
+When PCRE2 is compiled with Unicode support, in addition to these characters,
+five more Unicode "Pattern White Space" characters are recognized by
+PCRE2_EXTENDED. These are U+0085 (next line), U+200E (left-to-right mark),
+U+200F (right-to-left mark), U+2028 (line separator), and U+2029 (paragraph
+separator). This set of characters is the same as recognized by Perl's /x
+option. Note that the horizontal and vertical space characters that are matched
+by the \h and \v escapes in patterns are a much bigger set.
+</P>
+<P>
+As well as ignoring most white space, PCRE2_EXTENDED also causes characters
+between an unescaped # outside a character class and the next newline,
+inclusive, to be ignored, which makes it possible to include comments inside
+complicated patterns. Note that the end of this type of comment is a literal
+newline sequence in the pattern; escape sequences that happen to represent a
+newline do not count.
+</P>
+<P>
Which characters are interpreted as newlines can be specified by a setting in
the compile context that is passed to <b>pcre2_compile()</b> or by a special
sequence at the start of the pattern, as described in the section entitled
@@ -1531,9 +1552,11 @@
PCRE2_EXTENDED_MORE
</pre>
This option has the effect of PCRE2_EXTENDED, but, in addition, unescaped space
-and horizontal tab characters are ignored inside a character class.
-PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx option, and it can be
-changed within a pattern by a (?xx) option setting.
+and horizontal tab characters are ignored inside a character class. Note: only
+these two characters are ignored, not the full set of pattern white space
+characters that are ignored outside a character class. PCRE2_EXTENDED_MORE is
+equivalent to Perl's /xx option, and it can be changed within a pattern by a
+(?xx) option setting.
<pre>
PCRE2_FIRSTLINE
</pre>
@@ -3635,7 +3658,7 @@
</P>
<br><a name="SEC42" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 27 July 2018
+Last updated: 03 August 2018
<br>
Copyright © 1997-2018 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcre2pattern.html
===================================================================
--- code/trunk/doc/html/pcre2pattern.html 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/doc/html/pcre2pattern.html 2018-08-03 09:38:36 UTC (rev 977)
@@ -1628,9 +1628,11 @@
<br><a name="SEC13" href="#TOC1">INTERNAL OPTION SETTING</a><br>
<P>
The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL,
-PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options (which
-are Perl-compatible) can be changed from within the pattern by a sequence of
-Perl option letters enclosed between "(?" and ")". The option letters are
+PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options can be
+changed from within the pattern by a sequence of letters enclosed between "(?"
+and ")". These options are Perl-compatible, and are described in detail in the
+<a href="pcre2api.html"><b>pcre2api</b></a>
+documentation. The option letters are:
<pre>
i for PCRE2_CASELESS
m for PCRE2_MULTILINE
@@ -2275,8 +2277,9 @@
Because there may be many capturing parentheses in a pattern, all digits
following a backslash are taken as part of a potential backreference number.
If the pattern continues with a digit character, some delimiter must be used to
-terminate the backreference. If the PCRE2_EXTENDED option is set, this can be
-white space. Otherwise, the \g{ syntax or an empty comment (see
+terminate the backreference. If the PCRE2_EXTENDED or PCRE2_EXTENDED_MORE
+option is set, this can be white space. Otherwise, the \g{ syntax or an empty
+comment (see
<a href="#comments">"Comments"</a>
below) can be used.
</P>
@@ -2744,12 +2747,12 @@
<P>
The sequence (?# marks the start of a comment that continues up to the next
closing parenthesis. Nested parentheses are not permitted. If the
-PCRE2_EXTENDED option is set, an unescaped # character also introduces a
-comment, which in this case continues to immediately after the next newline
-character or character sequence in the pattern. Which characters are
-interpreted as newlines is controlled by an option passed to the compiling
-function or by a special sequence at the start of the pattern, as described in
-the section entitled
+PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is set, an unescaped # character
+also introduces a comment, which in this case continues to immediately after
+the next newline character or character sequence in the pattern. Which
+characters are interpreted as newlines is controlled by an option passed to the
+compiling function or by a special sequence at the start of the pattern, as
+described in the section entitled
<a href="#newlines">"Newline conventions"</a>
above. Note that the end of this type of comment is a literal newline sequence
in the pattern; escape sequences that happen to represent a newline do not
@@ -3108,10 +3111,11 @@
</P>
<P>
A closing parenthesis can be included in a name either as \) or between \Q
-and \E. In addition to backslash processing, if the PCRE2_EXTENDED option is
-also set, unescaped whitespace in verb names is skipped, and #-comments are
-recognized, exactly as in the rest of the pattern. PCRE2_EXTENDED does not
-affect verb names unless PCRE2_ALT_VERBNAMES is also set.
+and \E. In addition to backslash processing, if the PCRE2_EXTENDED or
+PCRE2_EXTENDED_MORE option is also set, unescaped whitespace in verb names is
+skipped, and #-comments are recognized, exactly as in the rest of the pattern.
+PCRE2_EXTENDED and PCRE2_EXTENDED_MORE do not affect verb names unless
+PCRE2_ALT_VERBNAMES is also set.
</P>
<P>
The maximum length of a name is 255 in the 8-bit library and 65535 in the
@@ -3590,7 +3594,7 @@
</P>
<br><a name="SEC30" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 28 July 2018
+Last updated: 03 August 2018
<br>
Copyright © 1997-2018 University of Cambridge.
<br>
Modified: code/trunk/doc/html/pcre2syntax.html
===================================================================
--- code/trunk/doc/html/pcre2syntax.html 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/doc/html/pcre2syntax.html 2018-08-03 09:38:36 UTC (rev 977)
@@ -446,6 +446,8 @@
</P>
<br><a name="SEC16" href="#TOC1">OPTION SETTING</a><br>
<P>
+Changes of these options within a group are automatically cancelled at the end
+of the group.
<pre>
(?i) caseless
(?J) allow duplicate names
@@ -632,7 +634,7 @@
</P>
<br><a name="SEC27" href="#TOC1">REVISION</a><br>
<P>
-Last updated: 28 July 2018
+Last updated: 01 August 2018
<br>
Copyright © 1997-2018 University of Cambridge.
<br>
Modified: code/trunk/doc/pcre2.txt
===================================================================
--- code/trunk/doc/pcre2.txt 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/doc/pcre2.txt 2018-08-03 09:38:36 UTC (rev 977)
@@ -869,10 +869,10 @@
When a pattern is compiled with the PCRE2_EXTENDED or
PCRE2_EXTENDED_MORE option, the newline convention affects the recogni-
- tion of white space and the end of internal comments starting with #.
- The value is saved with the compiled pattern for subsequent use by the
- JIT compiler and by the two interpreted matching functions,
- pcre2_match() and pcre2_dfa_match().
+ tion of the end of internal comments starting with #. The value is
+ saved with the compiled pattern for subsequent use by the JIT compiler
+ and by the two interpreted matching functions, pcre2_match() and
+ pcre2_dfa_match().
int pcre2_set_parens_nest_limit(pcre2_compile_context *ccontext,
uint32_t value);
@@ -1413,9 +1413,9 @@
processing is applied to verb names and only an unescaped closing
parenthesis terminates the name. A closing parenthesis can be included
in a name either as \) or between \Q and \E. If the PCRE2_EXTENDED or
- PCRE2_EXTENDED_MORE option is set, unescaped whitespace in verb names
- is skipped and #-comments are recognized in this mode, exactly as in
- the rest of the pattern.
+ PCRE2_EXTENDED_MORE option is set with PCRE2_ALT_VERBNAMES, unescaped
+ whitespace in verb names is skipped and #-comments are recognized,
+ exactly as in the rest of the pattern.
PCRE2_AUTO_CALLOUT
@@ -1498,233 +1498,254 @@
introduce various parenthesized subpatterns, nor within numerical quan-
tifiers such as {1,3}. Ignorable white space is permitted between an
item and a following quantifier and between a quantifier and a follow-
- ing + that indicates possessiveness.
+ ing + that indicates possessiveness. PCRE2_EXTENDED is equivalent to
+ Perl's /x option, and it can be changed within a pattern by a (?x)
+ option setting.
- PCRE2_EXTENDED also causes characters between an unescaped # outside a
- character class and the next newline, inclusive, to be ignored, which
- makes it possible to include comments inside complicated patterns. Note
- that the end of this type of comment is a literal newline sequence in
- the pattern; escape sequences that happen to represent a newline do not
- count. PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be
- changed within a pattern by a (?x) option setting.
+ When PCRE2 is compiled without Unicode support, PCRE2_EXTENDED recog-
+ nizes as white space only those characters with code points less than
+ 256 that are flagged as white space in its low-character table. The ta-
+ ble is normally created by pcre2_maketables(), which uses the isspace()
+ function to identify space characters. In most ASCII environments, the
+ relevant characters are those with code points 0x0009 (tab), 0x000A
+ (linefeed), 0x000B (vertical tab), 0x000C (formfeed), 0x000D (carriage
+ return), and 0x0020 (space).
+ When PCRE2 is compiled with Unicode support, in addition to these char-
+ acters, five more Unicode "Pattern White Space" characters are recog-
+ nized by PCRE2_EXTENDED. These are U+0085 (next line), U+200E (left-to-
+ right mark), U+200F (right-to-left mark), U+2028 (line separator), and
+ U+2029 (paragraph separator). This set of characters is the same as
+ recognized by Perl's /x option. Note that the horizontal and vertical
+ space characters that are matched by the \h and \v escapes in patterns
+ are a much bigger set.
+
+ As well as ignoring most white space, PCRE2_EXTENDED also causes char-
+ acters between an unescaped # outside a character class and the next
+ newline, inclusive, to be ignored, which makes it possible to include
+ comments inside complicated patterns. Note that the end of this type of
+ comment is a literal newline sequence in the pattern; escape sequences
+ that happen to represent a newline do not count.
+
Which characters are interpreted as newlines can be specified by a set-
- ting in the compile context that is passed to pcre2_compile() or by a
- special sequence at the start of the pattern, as described in the sec-
- tion entitled "Newline conventions" in the pcre2pattern documentation.
+ ting in the compile context that is passed to pcre2_compile() or by a
+ special sequence at the start of the pattern, as described in the sec-
+ tion entitled "Newline conventions" in the pcre2pattern documentation.
A default is defined when PCRE2 is built.
PCRE2_EXTENDED_MORE
- This option has the effect of PCRE2_EXTENDED, but, in addition,
- unescaped space and horizontal tab characters are ignored inside a
- character class. PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx
- option, and it can be changed within a pattern by a (?xx) option set-
+ This option has the effect of PCRE2_EXTENDED, but, in addition,
+ unescaped space and horizontal tab characters are ignored inside a
+ character class. Note: only these two characters are ignored, not the
+ full set of pattern white space characters that are ignored outside a
+ character class. PCRE2_EXTENDED_MORE is equivalent to Perl's /xx
+ option, and it can be changed within a pattern by a (?xx) option set-
ting.
PCRE2_FIRSTLINE
If this option is set, the start of an unanchored pattern match must be
- before or at the first newline in the subject string following the
- start of matching, though the matched text may continue over the new-
+ before or at the first newline in the subject string following the
+ start of matching, though the matched text may continue over the new-
line. If startoffset is non-zero, the limiting newline is not necessar-
- ily the first newline in the subject. For example, if the subject
+ ily the first newline in the subject. For example, if the subject
string is "abc\nxyz" (where \n represents a single-character newline) a
- pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
- greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
- general limiting facility. If PCRE2_FIRSTLINE is set with an offset
- limit, a match must occur in the first line and also within the offset
+ pattern match for "yz" succeeds with PCRE2_FIRSTLINE if startoffset is
+ greater than 3. See also PCRE2_USE_OFFSET_LIMIT, which provides a more
+ general limiting facility. If PCRE2_FIRSTLINE is set with an offset
+ limit, a match must occur in the first line and also within the offset
limit. In other words, whichever limit comes first is used.
PCRE2_LITERAL
If this option is set, all meta-characters in the pattern are disabled,
- and it is treated as a literal string. Matching literal strings with a
+ and it is treated as a literal string. Matching literal strings with a
regular expression engine is not the most efficient way of doing it. If
- you are doing a lot of literal matching and are worried about effi-
+ you are doing a lot of literal matching and are worried about effi-
ciency, you should consider using other approaches. The only other main
options that are allowed with PCRE2_LITERAL are: PCRE2_ANCHORED,
PCRE2_ENDANCHORED, PCRE2_AUTO_CALLOUT, PCRE2_CASELESS, PCRE2_FIRSTLINE,
PCRE2_NO_START_OPTIMIZE, PCRE2_NO_UTF_CHECK, PCRE2_UTF, and
- PCRE2_USE_OFFSET_LIMIT. The extra options PCRE2_EXTRA_MATCH_LINE and
- PCRE2_EXTRA_MATCH_WORD are also supported. Any other options cause an
+ PCRE2_USE_OFFSET_LIMIT. The extra options PCRE2_EXTRA_MATCH_LINE and
+ PCRE2_EXTRA_MATCH_WORD are also supported. Any other options cause an
error.
PCRE2_MATCH_UNSET_BACKREF
- If this option is set, a backreference to an unset subpattern group
- matches an empty string (by default this causes the current matching
- alternative to fail). A pattern such as (\1)(a) succeeds when this
- option is set (assuming it can find an "a" in the subject), whereas it
- fails by default, for Perl compatibility. Setting this option makes
+ If this option is set, a backreference to an unset subpattern group
+ matches an empty string (by default this causes the current matching
+ alternative to fail). A pattern such as (\1)(a) succeeds when this
+ option is set (assuming it can find an "a" in the subject), whereas it
+ fails by default, for Perl compatibility. Setting this option makes
PCRE2 behave more like ECMAscript (aka JavaScript).
PCRE2_MULTILINE
- By default, for the purposes of matching "start of line" and "end of
- line", PCRE2 treats the subject string as consisting of a single line
- of characters, even if it actually contains newlines. The "start of
- line" metacharacter (^) matches only at the start of the string, and
- the "end of line" metacharacter ($) matches only at the end of the
+ By default, for the purposes of matching "start of line" and "end of
+ line", PCRE2 treats the subject string as consisting of a single line
+ of characters, even if it actually contains newlines. The "start of
+ line" metacharacter (^) matches only at the start of the string, and
+ the "end of line" metacharacter ($) matches only at the end of the
string, or before a terminating newline (except when PCRE2_DOL-
- LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set,
+ LAR_ENDONLY is set). Note, however, that unless PCRE2_DOTALL is set,
the "any character" metacharacter (.) does not match at a newline. This
behaviour (for ^, $, and dot) is the same as Perl.
- When PCRE2_MULTILINE it is set, the "start of line" and "end of line"
- constructs match immediately following or immediately before internal
- newlines in the subject string, respectively, as well as at the very
- start and end. This is equivalent to Perl's /m option, and it can be
+ When PCRE2_MULTILINE it is set, the "start of line" and "end of line"
+ constructs match immediately following or immediately before internal
+ newlines in the subject string, respectively, as well as at the very
+ start and end. This is equivalent to Perl's /m option, and it can be
changed within a pattern by a (?m) option setting. Note that the "start
of line" metacharacter does not match after a newline at the end of the
- subject, for compatibility with Perl. However, you can change this by
- setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
- subject string, or no occurrences of ^ or $ in a pattern, setting
+ subject, for compatibility with Perl. However, you can change this by
+ setting the PCRE2_ALT_CIRCUMFLEX option. If there are no newlines in a
+ subject string, or no occurrences of ^ or $ in a pattern, setting
PCRE2_MULTILINE has no effect.
PCRE2_NEVER_BACKSLASH_C
- This option locks out the use of \C in the pattern that is being com-
- piled. This escape can cause unpredictable behaviour in UTF-8 or
- UTF-16 modes, because it may leave the current matching point in the
- middle of a multi-code-unit character. This option may be useful in
- applications that process patterns from external sources. Note that
+ This option locks out the use of \C in the pattern that is being com-
+ piled. This escape can cause unpredictable behaviour in UTF-8 or
+ UTF-16 modes, because it may leave the current matching point in the
+ middle of a multi-code-unit character. This option may be useful in
+ applications that process patterns from external sources. Note that
there is also a build-time option that permanently locks out the use of
\C.
PCRE2_NEVER_UCP
- This option locks out the use of Unicode properties for handling \B,
+ This option locks out the use of Unicode properties for handling \B,
\b, \D, \d, \S, \s, \W, \w, and some of the POSIX character classes, as
- described for the PCRE2_UCP option below. In particular, it prevents
- the creator of the pattern from enabling this facility by starting the
- pattern with (*UCP). This option may be useful in applications that
+ described for the PCRE2_UCP option below. In particular, it prevents
+ the creator of the pattern from enabling this facility by starting the
+ pattern with (*UCP). This option may be useful in applications that
process patterns from external sources. The option combination PCRE_UCP
and PCRE_NEVER_UCP causes an error.
PCRE2_NEVER_UTF
- This option locks out interpretation of the pattern as UTF-8, UTF-16,
+ This option locks out interpretation of the pattern as UTF-8, UTF-16,
or UTF-32, depending on which library is in use. In particular, it pre-
- vents the creator of the pattern from switching to UTF interpretation
- by starting the pattern with (*UTF). This option may be useful in
- applications that process patterns from external sources. The combina-
+ vents the creator of the pattern from switching to UTF interpretation
+ by starting the pattern with (*UTF). This option may be useful in
+ applications that process patterns from external sources. The combina-
tion of PCRE2_UTF and PCRE2_NEVER_UTF causes an error.
PCRE2_NO_AUTO_CAPTURE
If this option is set, it disables the use of numbered capturing paren-
- theses in the pattern. Any opening parenthesis that is not followed by
- ? behaves as if it were followed by ?: but named parentheses can still
+ theses in the pattern. Any opening parenthesis that is not followed by
+ ? behaves as if it were followed by ?: but named parentheses can still
be used for capturing (and they acquire numbers in the usual way). This
- is the same as Perl's /n option. Note that, when this option is set,
- references to capturing groups (backreferences or recursion/subroutine
- calls) may only refer to named groups, though the reference can be by
+ is the same as Perl's /n option. Note that, when this option is set,
+ references to capturing groups (backreferences or recursion/subroutine
+ calls) may only refer to named groups, though the reference can be by
name or by number.
PCRE2_NO_AUTO_POSSESS
If this option is set, it disables "auto-possessification", which is an
- optimization that, for example, turns a+b into a++b in order to avoid
- backtracks into a+ that can never be successful. However, if callouts
- are in use, auto-possessification means that some callouts are never
+ optimization that, for example, turns a+b into a++b in order to avoid
+ backtracks into a+ that can never be successful. However, if callouts
+ are in use, auto-possessification means that some callouts are never
taken. You can set this option if you want the matching functions to do
- a full unoptimized search and run all the callouts, but it is mainly
+ a full unoptimized search and run all the callouts, but it is mainly
provided for testing purposes.
PCRE2_NO_DOTSTAR_ANCHOR
If this option is set, it disables an optimization that is applied when
- .* is the first significant item in a top-level branch of a pattern,
- and all the other branches also start with .* or with \A or \G or ^.
- The optimization is automatically disabled for .* if it is inside an
- atomic group or a capturing group that is the subject of a backrefer-
- ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti-
- mization is not disabled, such a pattern is automatically anchored if
+ .* is the first significant item in a top-level branch of a pattern,
+ and all the other branches also start with .* or with \A or \G or ^.
+ The optimization is automatically disabled for .* if it is inside an
+ atomic group or a capturing group that is the subject of a backrefer-
+ ence, or if the pattern contains (*PRUNE) or (*SKIP). When the opti-
+ mization is not disabled, such a pattern is automatically anchored if
PCRE2_DOTALL is set for all the .* items and PCRE2_MULTILINE is not set
- for any ^ items. Otherwise, the fact that any match must start either
- at the start of the subject or following a newline is remembered. Like
+ for any ^ items. Otherwise, the fact that any match must start either
+ at the start of the subject or following a newline is remembered. Like
other optimizations, this can cause callouts to be skipped.
PCRE2_NO_START_OPTIMIZE
- This is an option whose main effect is at matching time. It does not
+ This is an option whose main effect is at matching time. It does not
change what pcre2_compile() generates, but it does affect the output of
the JIT compiler.
- There are a number of optimizations that may occur at the start of a
- match, in order to speed up the process. For example, if it is known
- that an unanchored match must start with a specific code unit value,
- the matching code searches the subject for that value, and fails imme-
- diately if it cannot find it, without actually running the main match-
- ing function. This means that a special item such as (*COMMIT) at the
- start of a pattern is not considered until after a suitable starting
- point for the match has been found. Also, when callouts or (*MARK)
- items are in use, these "start-up" optimizations can cause them to be
- skipped if the pattern is never actually used. The start-up optimiza-
- tions are in effect a pre-scan of the subject that takes place before
+ There are a number of optimizations that may occur at the start of a
+ match, in order to speed up the process. For example, if it is known
+ that an unanchored match must start with a specific code unit value,
+ the matching code searches the subject for that value, and fails imme-
+ diately if it cannot find it, without actually running the main match-
+ ing function. This means that a special item such as (*COMMIT) at the
+ start of a pattern is not considered until after a suitable starting
+ point for the match has been found. Also, when callouts or (*MARK)
+ items are in use, these "start-up" optimizations can cause them to be
+ skipped if the pattern is never actually used. The start-up optimiza-
+ tions are in effect a pre-scan of the subject that takes place before
the pattern is run.
The PCRE2_NO_START_OPTIMIZE option disables the start-up optimizations,
- possibly causing performance to suffer, but ensuring that in cases
- where the result is "no match", the callouts do occur, and that items
+ possibly causing performance to suffer, but ensuring that in cases
+ where the result is "no match", the callouts do occur, and that items
such as (*COMMIT) and (*MARK) are considered at every possible starting
position in the subject string.
- Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching
+ Setting PCRE2_NO_START_OPTIMIZE may change the outcome of a matching
operation. Consider the pattern
(*COMMIT)ABC
- When this is compiled, PCRE2 records the fact that a match must start
- with the character "A". Suppose the subject string is "DEFABC". The
- start-up optimization scans along the subject, finds "A" and runs the
- first match attempt from there. The (*COMMIT) item means that the pat-
- tern must match the current starting position, which in this case, it
- does. However, if the same match is run with PCRE2_NO_START_OPTIMIZE
- set, the initial scan along the subject string does not happen. The
- first match attempt is run starting from "D" and when this fails,
- (*COMMIT) prevents any further matches being tried, so the overall
+ When this is compiled, PCRE2 records the fact that a match must start
+ with the character "A". Suppose the subject string is "DEFABC". The
+ start-up optimization scans along the subject, finds "A" and runs the
+ first match attempt from there. The (*COMMIT) item means that the pat-
+ tern must match the current starting position, which in this case, it
+ does. However, if the same match is run with PCRE2_NO_START_OPTIMIZE
+ set, the initial scan along the subject string does not happen. The
+ first match attempt is run starting from "D" and when this fails,
+ (*COMMIT) prevents any further matches being tried, so the overall
result is "no match".
- There are also other start-up optimizations. For example, a minimum
+ There are also other start-up optimizations. For example, a minimum
length for the subject may be recorded. Consider the pattern
(*MARK:A)(X|Y)
- The minimum length for a match is one character. If the subject is
+ The minimum length for a match is one character. If the subject is
"ABC", there will be attempts to match "ABC", "BC", and "C". An attempt
to match an empty string at the end of the subject does not take place,
- because PCRE2 knows that the subject is now too short, and so the
- (*MARK) is never encountered. In this case, the optimization does not
+ because PCRE2 knows that the subject is now too short, and so the
+ (*MARK) is never encountered. In this case, the optimization does not
affect the overall match result, which is still "no match", but it does
affect the auxiliary information that is returned.
PCRE2_NO_UTF_CHECK
- When PCRE2_UTF is set, the validity of the pattern as a UTF string is
- automatically checked. There are discussions about the validity of
- UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode
- document. If an invalid UTF sequence is found, pcre2_compile() returns
+ When PCRE2_UTF is set, the validity of the pattern as a UTF string is
+ automatically checked. There are discussions about the validity of
+ UTF-8 strings, UTF-16 strings, and UTF-32 strings in the pcre2unicode
+ document. If an invalid UTF sequence is found, pcre2_compile() returns
a negative error code.
- If you know that your pattern is a valid UTF string, and you want to
- skip this check for performance reasons, you can set the
- PCRE2_NO_UTF_CHECK option. When it is set, the effect of passing an
+ If you know that your pattern is a valid UTF string, and you want to
+ skip this check for performance reasons, you can set the
+ PCRE2_NO_UTF_CHECK option. When it is set, the effect of passing an
invalid UTF string as a pattern is undefined. It may cause your program
to crash or loop.
Note that this option can also be passed to pcre2_match() and
- pcre_dfa_match(), to suppress UTF validity checking of the subject
+ pcre_dfa_match(), to suppress UTF validity checking of the subject
string.
Note also that setting PCRE2_NO_UTF_CHECK at compile time does not dis-
- able the error that is given if an escape sequence for an invalid Uni-
- code code point is encountered in the pattern. In particular, the so-
- called "surrogate" code points (0xd800 to 0xdfff) are invalid. If you
- want to allow escape sequences such as \x{d800} you can set the
- PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option, as described in the
- section entitled "Extra compile options" below. However, this is pos-
+ able the error that is given if an escape sequence for an invalid Uni-
+ code code point is encountered in the pattern. In particular, the so-
+ called "surrogate" code points (0xd800 to 0xdfff) are invalid. If you
+ want to allow escape sequences such as \x{d800} you can set the
+ PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option, as described in the
+ section entitled "Extra compile options" below. However, this is pos-
sible only in UTF-8 and UTF-32 modes, because these values are not rep-
resentable in UTF-16.
@@ -1731,106 +1752,106 @@
PCRE2_UCP
This option changes the way PCRE2 processes \B, \b, \D, \d, \S, \s, \W,
- \w, and some of the POSIX character classes. By default, only ASCII
- characters are recognized, but if PCRE2_UCP is set, Unicode properties
- are used instead to classify characters. More details are given in the
+ \w, and some of the POSIX character classes. By default, only ASCII
+ characters are recognized, but if PCRE2_UCP is set, Unicode properties
+ are used instead to classify characters. More details are given in the
section on generic character types in the pcre2pattern page. If you set
- PCRE2_UCP, matching one of the items it affects takes much longer. The
- option is available only if PCRE2 has been compiled with Unicode sup-
+ PCRE2_UCP, matching one of the items it affects takes much longer. The
+ option is available only if PCRE2 has been compiled with Unicode sup-
port (which is the default).
PCRE2_UNGREEDY
- This option inverts the "greediness" of the quantifiers so that they
- are not greedy by default, but become greedy if followed by "?". It is
- not compatible with Perl. It can also be set by a (?U) option setting
+ This option inverts the "greediness" of the quantifiers so that they
+ are not greedy by default, but become greedy if followed by "?". It is
+ not compatible with Perl. It can also be set by a (?U) option setting
within the pattern.
PCRE2_USE_OFFSET_LIMIT
This option must be set for pcre2_compile() if pcre2_set_offset_limit()
- is going to be used to set a non-default offset limit in a match con-
- text for matches that use this pattern. An error is generated if an
- offset limit is set without this option. For more details, see the
- description of pcre2_set_offset_limit() in the section that describes
+ is going to be used to set a non-default offset limit in a match con-
+ text for matches that use this pattern. An error is generated if an
+ offset limit is set without this option. For more details, see the
+ description of pcre2_set_offset_limit() in the section that describes
match contexts. See also the PCRE2_FIRSTLINE option above.
PCRE2_UTF
- This option causes PCRE2 to regard both the pattern and the subject
- strings that are subsequently processed as strings of UTF characters
- instead of single-code-unit strings. It is available when PCRE2 is
- built to include Unicode support (which is the default). If Unicode
- support is not available, the use of this option provokes an error.
- Details of how PCRE2_UTF changes the behaviour of PCRE2 are given in
+ This option causes PCRE2 to regard both the pattern and the subject
+ strings that are subsequently processed as strings of UTF characters
+ instead of single-code-unit strings. It is available when PCRE2 is
+ built to include Unicode support (which is the default). If Unicode
+ support is not available, the use of this option provokes an error.
+ Details of how PCRE2_UTF changes the behaviour of PCRE2 are given in
the pcre2unicode page.
Extra compile options
- Unlike the main compile-time options, the extra options are not saved
+ Unlike the main compile-time options, the extra options are not saved
with the compiled pattern. The option bits that can be set in a compile
- context by calling the pcre2_set_compile_extra_options() function are
+ context by calling the pcre2_set_compile_extra_options() function are
as follows:
PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES
- This option applies when compiling a pattern in UTF-8 or UTF-32 mode.
- It is forbidden in UTF-16 mode, and ignored in non-UTF modes. Unicode
+ This option applies when compiling a pattern in UTF-8 or UTF-32 mode.
+ It is forbidden in UTF-16 mode, and ignored in non-UTF modes. Unicode
"surrogate" code points in the range 0xd800 to 0xdfff are used in pairs
- in UTF-16 to encode code points with values in the range 0x10000 to
- 0x10ffff. The surrogates cannot therefore be represented in UTF-16.
+ in UTF-16 to encode code points with values in the range 0x10000 to
+ 0x10ffff. The surrogates cannot therefore be represented in UTF-16.
They can be represented in UTF-8 and UTF-32, but are defined as invalid
- code points, and cause errors if encountered in a UTF-8 or UTF-32
+ code points, and cause errors if encountered in a UTF-8 or UTF-32
string that is being checked for validity by PCRE2.
- These values also cause errors if encountered in escape sequences such
+ These values also cause errors if encountered in escape sequences such
as \x{d912} within a pattern. However, it seems that some applications,
- when using PCRE2 to check for unwanted characters in UTF-8 strings,
- explicitly test for the surrogates using escape sequences. The
- PCRE2_NO_UTF_CHECK option does not disable the error that occurs,
- because it applies only to the testing of input strings for UTF valid-
+ when using PCRE2 to check for unwanted characters in UTF-8 strings,
+ explicitly test for the surrogates using escape sequences. The
+ PCRE2_NO_UTF_CHECK option does not disable the error that occurs,
+ because it applies only to the testing of input strings for UTF valid-
ity.
- If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
- gate code point values in UTF-8 and UTF-32 patterns no longer provoke
- errors and are incorporated in the compiled pattern. However, they can
- only match subject characters if the matching function is called with
+ If the extra option PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES is set, surro-
+ gate code point values in UTF-8 and UTF-32 patterns no longer provoke
+ errors and are incorporated in the compiled pattern. However, they can
+ only match subject characters if the matching function is called with
PCRE2_NO_UTF_CHECK set.
PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL
- This is a dangerous option. Use with care. By default, an unrecognized
- escape such as \j or a malformed one such as \x{2z} causes a compile-
+ This is a dangerous option. Use with care. By default, an unrecognized
+ escape such as \j or a malformed one such as \x{2z} causes a compile-
time error when detected by pcre2_compile(). Perl is somewhat inconsis-
- tent in handling such items: for example, \j is treated as a literal
- "j", and non-hexadecimal digits in \x{} are just ignored, though warn-
- ings are given in both cases if Perl's warning switch is enabled. How-
- ever, a malformed octal number after \o{ always causes an error in
+ tent in handling such items: for example, \j is treated as a literal
+ "j", and non-hexadecimal digits in \x{} are just ignored, though warn-
+ ings are given in both cases if Perl's warning switch is enabled. How-
+ ever, a malformed octal number after \o{ always causes an error in
Perl.
- If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL extra option is passed to
- pcre2_compile(), all unrecognized or erroneous escape sequences are
- treated as single-character escapes. For example, \j is a literal "j"
- and \x{2z} is treated as the literal string "x{2z}". Setting this
- option means that typos in patterns may go undetected and have unex-
+ If the PCRE2_EXTRA_BAD_ESCAPE_IS_LITERAL extra option is passed to
+ pcre2_compile(), all unrecognized or erroneous escape sequences are
+ treated as single-character escapes. For example, \j is a literal "j"
+ and \x{2z} is treated as the literal string "x{2z}". Setting this
+ option means that typos in patterns may go undetected and have unex-
pected results. This is a dangerous option. Use with care.
PCRE2_EXTRA_MATCH_LINE
- This option is provided for use by the -x option of pcre2grep. It
- causes the pattern only to match complete lines. This is achieved by
- automatically inserting the code for "^(?:" at the start of the com-
- piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
- the matched line may be in the middle of the subject string. This
+ This option is provided for use by the -x option of pcre2grep. It
+ causes the pattern only to match complete lines. This is achieved by
+ automatically inserting the code for "^(?:" at the start of the com-
+ piled pattern and ")$" at the end. Thus, when PCRE2_MULTILINE is set,
+ the matched line may be in the middle of the subject string. This
option can be used with PCRE2_LITERAL.
PCRE2_EXTRA_MATCH_WORD
- This option is provided for use by the -w option of pcre2grep. It
- causes the pattern only to match strings that have a word boundary at
- the start and the end. This is achieved by automatically inserting the
- code for "\b(?:" at the start of the compiled pattern and ")\b" at the
- end. The option may be used with PCRE2_LITERAL. However, it is ignored
+ This option is provided for use by the -w option of pcre2grep. It
+ causes the pattern only to match strings that have a word boundary at
+ the start and the end. This is achieved by automatically inserting the
+ code for "\b(?:" at the start of the compiled pattern and ")\b" at the
+ end. The option may be used with PCRE2_LITERAL. However, it is ignored
if PCRE2_EXTRA_MATCH_LINE is also set.
@@ -1853,53 +1874,53 @@
void pcre2_jit_stack_free(pcre2_jit_stack *jit_stack);
- These functions provide support for JIT compilation, which, if the
- just-in-time compiler is available, further processes a compiled pat-
+ These functions provide support for JIT compilation, which, if the
+ just-in-time compiler is available, further processes a compiled pat-
tern into machine code that executes much faster than the pcre2_match()
- interpretive matching function. Full details are given in the pcre2jit
+ interpretive matching function. Full details are given in the pcre2jit
documentation.
- JIT compilation is a heavyweight optimization. It can take some time
- for patterns to be analyzed, and for one-off matches and simple pat-
- terns the benefit of faster execution might be offset by a much slower
- compilation time. Most (but not all) patterns can be optimized by the
+ JIT compilation is a heavyweight optimization. It can take some time
+ for patterns to be analyzed, and for one-off matches and simple pat-
+ terns the benefit of faster execution might be offset by a much slower
+ compilation time. Most (but not all) patterns can be optimized by the
JIT compiler.
LOCALE SUPPORT
- PCRE2 handles caseless matching, and determines whether characters are
- letters, digits, or whatever, by reference to a set of tables, indexed
- by character code point. This applies only to characters whose code
- points are less than 256. By default, higher-valued code points never
- match escapes such as \w or \d. However, if PCRE2 is built with Uni-
+ PCRE2 handles caseless matching, and determines whether characters are
+ letters, digits, or whatever, by reference to a set of tables, indexed
+ by character code point. This applies only to characters whose code
+ points are less than 256. By default, higher-valued code points never
+ match escapes such as \w or \d. However, if PCRE2 is built with Uni-
code support, all characters can be tested with \p and \P, or, alterna-
- tively, the PCRE2_UCP option can be set when a pattern is compiled;
- this causes \w and friends to use Unicode property support instead of
+ tively, the PCRE2_UCP option can be set when a pattern is compiled;
+ this causes \w and friends to use Unicode property support instead of
the built-in tables.
- The use of locales with Unicode is discouraged. If you are handling
- characters with code points greater than 128, you should either use
+ The use of locales with Unicode is discouraged. If you are handling
+ characters with code points greater than 128, you should either use
Unicode support, or use locales, but not try to mix the two.
- PCRE2 contains an internal set of character tables that are used by
- default. These are sufficient for many applications. Normally, the
+ PCRE2 contains an internal set of character tables that are used by
+ default. These are sufficient for many applications. Normally, the
internal tables recognize only ASCII characters. However, when PCRE2 is
built, it is possible to cause the internal tables to be rebuilt in the
default "C" locale of the local system, which may cause them to be dif-
ferent.
- The internal tables can be overridden by tables supplied by the appli-
- cation that calls PCRE2. These may be created in a different locale
- from the default. As more and more applications change to using Uni-
+ The internal tables can be overridden by tables supplied by the appli-
+ cation that calls PCRE2. These may be created in a different locale
+ from the default. As more and more applications change to using Uni-
code, the need for this locale support is expected to die away.
- External tables are built by calling the pcre2_maketables() function,
- in the relevant locale. The result can be passed to pcre2_compile() as
- often as necessary, by creating a compile context and calling
- pcre2_set_character_tables() to set the tables pointer therein. For
- example, to build and use tables that are appropriate for the French
- locale (where accented characters with values greater than 128 are
+ External tables are built by calling the pcre2_maketables() function,
+ in the relevant locale. The result can be passed to pcre2_compile() as
+ often as necessary, by creating a compile context and calling
+ pcre2_set_character_tables() to set the tables pointer therein. For
+ example, to build and use tables that are appropriate for the French
+ locale (where accented characters with values greater than 128 are
treated as letters), the following code could be used:
setlocale(LC_CTYPE, "fr_FR");
@@ -1908,15 +1929,15 @@
pcre2_set_character_tables(ccontext, tables);
re = pcre2_compile(..., ccontext);
- The locale name "fr_FR" is used on Linux and other Unix-like systems;
- if you are using Windows, the name for the French locale is "french".
- It is the caller's responsibility to ensure that the memory containing
+ The locale name "fr_FR" is used on Linux and other Unix-like systems;
+ if you are using Windows, the name for the French locale is "french".
+ It is the caller's responsibility to ensure that the memory containing
the tables remains available for as long as it is needed.
The pointer that is passed (via the compile context) to pcre2_compile()
- is saved with the compiled pattern, and the same tables are used by
- pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com-
- pilation and matching both happen in the same locale, but different
+ is saved with the compiled pattern, and the same tables are used by
+ pcre2_match() and pcre_dfa_match(). Thus, for any single pattern, com-
+ pilation and matching both happen in the same locale, but different
patterns can be processed in different locales.
@@ -1924,13 +1945,13 @@
int pcre2_pattern_info(const pcre2 *code, uint32_t what, void *where);
- The pcre2_pattern_info() function returns general information about a
+ The pcre2_pattern_info() function returns general information about a
compiled pattern. For information about callouts, see the next section.
- The first argument for pcre2_pattern_info() is a pointer to the com-
+ The first argument for pcre2_pattern_info() is a pointer to the com-
piled pattern. The second argument specifies which piece of information
- is required, and the third argument is a pointer to a variable to
- receive the data. If the third argument is NULL, the first argument is
- ignored, and the function returns the size in bytes of the variable
+ is required, and the third argument is a pointer to a variable to
+ receive the data. If the third argument is NULL, the first argument is
+ ignored, and the function returns the size in bytes of the variable
that is required for the information requested. Otherwise, the yield of
the function is zero for success, or one of the following negative num-
bers:
@@ -1940,9 +1961,9 @@
PCRE2_ERROR_BADOPTION the value of what was invalid
PCRE2_ERROR_UNSET the requested field is not set
- The "magic number" is placed at the start of each compiled pattern as
- an simple check against passing an arbitrary memory pointer. Here is a
- typical call of pcre2_pattern_info(), to obtain the length of the com-
+ The "magic number" is placed at the start of each compiled pattern as
+ an simple check against passing an arbitrary memory pointer. Here is a
+ typical call of pcre2_pattern_info(), to obtain the length of the com-
piled pattern:
int rc;
@@ -1960,22 +1981,22 @@
PCRE2_INFO_EXTRAOPTIONS
Return copies of the pattern's options. The third argument should point
- to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the
- options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
- TIONS returns the compile options as modified by any top-level (*XXX)
- option settings such as (*UTF) at the start of the pattern itself.
- PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in the
- compile context by calling the pcre2_set_compile_extra_options() func-
+ to a uint32_t variable. PCRE2_INFO_ARGOPTIONS returns exactly the
+ options that were passed to pcre2_compile(), whereas PCRE2_INFO_ALLOP-
+ TIONS returns the compile options as modified by any top-level (*XXX)
+ option settings such as (*UTF) at the start of the pattern itself.
+ PCRE2_INFO_EXTRAOPTIONS returns the extra options that were set in the
+ compile context by calling the pcre2_set_compile_extra_options() func-
tion.
- For example, if the pattern /(*UTF)abc/ is compiled with the
- PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is
- PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can
- change within a pattern do not affect the result of PCRE2_INFO_ALLOP-
+ For example, if the pattern /(*UTF)abc/ is compiled with the
+ PCRE2_EXTENDED option, the result for PCRE2_INFO_ALLOPTIONS is
+ PCRE2_EXTENDED and PCRE2_UTF. Option settings such as (?i) that can
+ change within a pattern do not affect the result of PCRE2_INFO_ALLOP-
TIONS, even if they appear right at the start of the pattern. (This was
different in some earlier releases.)
- A pattern compiled without PCRE2_ANCHORED is automatically anchored by
+ A pattern compiled without PCRE2_ANCHORED is automatically anchored by
PCRE2 if the first significant item in every top-level branch is one of
the following:
@@ -1984,7 +2005,7 @@
\G always
.* sometimes - see below
- When .* is the first significant item, anchoring is possible only when
+ When .* is the first significant item, anchoring is possible only when
all the following are true:
.* is not in an atomic group
@@ -1994,71 +2015,71 @@
Neither (*PRUNE) nor (*SKIP) appears in the pattern
PCRE2_NO_DOTSTAR_ANCHOR is not set
- For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in
+ For patterns that are auto-anchored, the PCRE2_ANCHORED bit is set in
the options returned for PCRE2_INFO_ALLOPTIONS.
PCRE2_INFO_BACKREFMAX
- Return the number of the highest backreference in the pattern. The
- third argument should point to an uint32_t variable. Named subpatterns
- acquire numbers as well as names, and these count towards the highest
- backreference. Backreferences such as \4 or \g{12} match the captured
- characters of the given group, but in addition, the check that a cap-
- turing group is set in a conditional subpattern such as (?(3)a|b) is
+ Return the number of the highest backreference in the pattern. The
+ third argument should point to an uint32_t variable. Named subpatterns
+ acquire numbers as well as names, and these count towards the highest
+ backreference. Backreferences such as \4 or \g{12} match the captured
+ characters of the given group, but in addition, the check that a cap-
+ turing group is set in a conditional subpattern such as (?(3)a|b) is
also a backreference. Zero is returned if there are no backreferences.
PCRE2_INFO_BSR
- The output is a uint32_t integer whose value indicates what character
- sequences the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
- means that \R matches any Unicode line ending sequence; a value of
+ The output is a uint32_t integer whose value indicates what character
+ sequences the \R escape sequence matches. A value of PCRE2_BSR_UNICODE
+ means that \R matches any Unicode line ending sequence; a value of
PCRE2_BSR_ANYCRLF means that \R matches only CR, LF, or CRLF.
PCRE2_INFO_CAPTURECOUNT
- Return the highest capturing subpattern number in the pattern. In pat-
+ Return the highest capturing subpattern number in the pattern. In pat-
terns where (?| is not used, this is also the total number of capturing
subpatterns. The third argument should point to an uint32_t variable.
PCRE2_INFO_DEPTHLIMIT
- If the pattern set a backtracking depth limit by including an item of
- the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
+ If the pattern set a backtracking depth limit by including an item of
+ the form (*LIMIT_DEPTH=nnnn) at the start, the value is returned. The
third argument should point to a uint32_t integer. If no such value has
- been set, the call to pcre2_pattern_info() returns the error
+ been set, the call to pcre2_pattern_info() returns the error
PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
- ing if it is less than the limit set or defaulted by the caller of the
+ ing if it is less than the limit set or defaulted by the caller of the
match function.
PCRE2_INFO_FIRSTBITMAP
- In the absence of a single first code unit for a non-anchored pattern,
- pcre2_compile() may construct a 256-bit table that defines a fixed set
- of values for the first code unit in any match. For example, a pattern
- that starts with [abc] results in a table with three bits set. When
- code unit values greater than 255 are supported, the flag bit for 255
- means "any code unit of value 255 or above". If such a table was con-
- structed, a pointer to it is returned. Otherwise NULL is returned. The
+ In the absence of a single first code unit for a non-anchored pattern,
+ pcre2_compile() may construct a 256-bit table that defines a fixed set
+ of values for the first code unit in any match. For example, a pattern
+ that starts with [abc] results in a table with three bits set. When
+ code unit values greater than 255 are supported, the flag bit for 255
+ means "any code unit of value 255 or above". If such a table was con-
+ structed, a pointer to it is returned. Otherwise NULL is returned. The
third argument should point to a const uint8_t * variable.
PCRE2_INFO_FIRSTCODETYPE
Return information about the first code unit of any matched string, for
- a non-anchored pattern. The third argument should point to an uint32_t
- variable. If there is a fixed first value, for example, the letter "c"
- from a pattern such as (cat|cow|coyote), 1 is returned, and the value
- can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
- first value, but it is known that a match can occur only at the start
- of the subject or following a newline in the subject, 2 is returned.
+ a non-anchored pattern. The third argument should point to an uint32_t
+ variable. If there is a fixed first value, for example, the letter "c"
+ from a pattern such as (cat|cow|coyote), 1 is returned, and the value
+ can be retrieved using PCRE2_INFO_FIRSTCODEUNIT. If there is no fixed
+ first value, but it is known that a match can occur only at the start
+ of the subject or following a newline in the subject, 2 is returned.
Otherwise, and for anchored patterns, 0 is returned.
PCRE2_INFO_FIRSTCODEUNIT
- Return the value of the first code unit of any matched string for a
- pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
- The third argument should point to an uint32_t variable. In the 8-bit
- library, the value is always less than 256. In the 16-bit library the
- value can be up to 0xffff. In the 32-bit library in UTF-32 mode the
+ Return the value of the first code unit of any matched string for a
+ pattern where PCRE2_INFO_FIRSTCODETYPE returns 1; otherwise return 0.
+ The third argument should point to an uint32_t variable. In the 8-bit
+ library, the value is always less than 256. In the 16-bit library the
+ value can be up to 0xffff. In the 32-bit library in UTF-32 mode the
value can be up to 0x10ffff, and up to 0xffffffff when not using UTF-32
mode.
@@ -2065,23 +2086,23 @@
PCRE2_INFO_FRAMESIZE
Return the size (in bytes) of the data frames that are used to remember
- backtracking positions when the pattern is processed by pcre2_match()
- without the use of JIT. The third argument should point to a size_t
+ backtracking positions when the pattern is processed by pcre2_match()
+ without the use of JIT. The third argument should point to a size_t
variable. The frame size depends on the number of capturing parentheses
- in the pattern. Each additional capturing group adds two PCRE2_SIZE
+ in the pattern. Each additional capturing group adds two PCRE2_SIZE
variables.
PCRE2_INFO_HASBACKSLASHC
- Return 1 if the pattern contains any instances of \C, otherwise 0. The
+ Return 1 if the pattern contains any instances of \C, otherwise 0. The
third argument should point to an uint32_t variable.
PCRE2_INFO_HASCRORLF
- Return 1 if the pattern contains any explicit matches for CR or LF
+ Return 1 if the pattern contains any explicit matches for CR or LF
characters, otherwise 0. The third argument should point to an uint32_t
- variable. An explicit match is either a literal CR or LF character, or
- \r or \n or one of the equivalent hexadecimal or octal escape
+ variable. An explicit match is either a literal CR or LF character, or
+ \r or \n or one of the equivalent hexadecimal or octal escape
sequences.
PCRE2_INFO_HEAPLIMIT
@@ -2089,81 +2110,81 @@
If the pattern set a heap memory limit by including an item of the form
(*LIMIT_HEAP=nnnn) at the start, the value is returned. The third argu-
ment should point to a uint32_t integer. If no such value has been set,
- the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
- Note that this limit will only be used during matching if it is less
+ the call to pcre2_pattern_info() returns the error PCRE2_ERROR_UNSET.
+ Note that this limit will only be used during matching if it is less
than the limit set or defaulted by the caller of the match function.
PCRE2_INFO_JCHANGED
- Return 1 if the (?J) or (?-J) option setting is used in the pattern,
- otherwise 0. The third argument should point to an uint32_t variable.
- (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
+ Return 1 if the (?J) or (?-J) option setting is used in the pattern,
+ otherwise 0. The third argument should point to an uint32_t variable.
+ (?J) and (?-J) set and unset the local PCRE2_DUPNAMES option, respec-
tively.
PCRE2_INFO_JITSIZE
- If the compiled pattern was successfully processed by pcre2_jit_com-
- pile(), return the size of the JIT compiled code, otherwise return
+ If the compiled pattern was successfully processed by pcre2_jit_com-
+ pile(), return the size of the JIT compiled code, otherwise return
zero. The third argument should point to a size_t variable.
PCRE2_INFO_LASTCODETYPE
- Returns 1 if there is a rightmost literal code unit that must exist in
- any matched string, other than at its start. The third argument should
- point to an uint32_t variable. If there is no such value, 0 is
- returned. When 1 is returned, the code unit value itself can be
- retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last
- literal value is recorded only if it follows something of variable
- length. For example, for the pattern /^a\d+z\d+/ the returned value is
- 1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/
+ Returns 1 if there is a rightmost literal code unit that must exist in
+ any matched string, other than at its start. The third argument should
+ point to an uint32_t variable. If there is no such value, 0 is
+ returned. When 1 is returned, the code unit value itself can be
+ retrieved using PCRE2_INFO_LASTCODEUNIT. For anchored patterns, a last
+ literal value is recorded only if it follows something of variable
+ length. For example, for the pattern /^a\d+z\d+/ the returned value is
+ 1 (with "z" returned from PCRE2_INFO_LASTCODEUNIT), but for /^a\dz\d/
the returned value is 0.
PCRE2_INFO_LASTCODEUNIT
- Return the value of the rightmost literal code unit that must exist in
- any matched string, other than at its start, for a pattern where
+ Return the value of the rightmost literal code unit that must exist in
+ any matched string, other than at its start, for a pattern where
PCRE2_INFO_LASTCODETYPE returns 1. Otherwise, return 0. The third argu-
ment should point to an uint32_t variable.
PCRE2_INFO_MATCHEMPTY
- Return 1 if the pattern might match an empty string, otherwise 0. The
- third argument should point to an uint32_t variable. When a pattern
+ Return 1 if the pattern might match an empty string, otherwise 0. The
+ third argument should point to an uint32_t variable. When a pattern
contains recursive subroutine calls it is not always possible to deter-
- mine whether or not it can match an empty string. PCRE2 takes a cau-
+ mine whether or not it can match an empty string. PCRE2 takes a cau-
tious approach and returns 1 in such cases.
PCRE2_INFO_MATCHLIMIT
- If the pattern set a match limit by including an item of the form
- (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third
- argument should point to a uint32_t integer. If no such value has been
- set, the call to pcre2_pattern_info() returns the error
+ If the pattern set a match limit by including an item of the form
+ (*LIMIT_MATCH=nnnn) at the start, the value is returned. The third
+ argument should point to a uint32_t integer. If no such value has been
+ set, the call to pcre2_pattern_info() returns the error
PCRE2_ERROR_UNSET. Note that this limit will only be used during match-
- ing if it is less than the limit set or defaulted by the caller of the
+ ing if it is less than the limit set or defaulted by the caller of the
match function.
PCRE2_INFO_MAXLOOKBEHIND
Return the number of characters (not code units) in the longest lookbe-
- hind assertion in the pattern. The third argument should point to a
- uint32_t integer. This information is useful when doing multi-segment
- matching using the partial matching facilities. Note that the simple
+ hind assertion in the pattern. The third argument should point to a
+ uint32_t integer. This information is useful when doing multi-segment
+ matching using the partial matching facilities. Note that the simple
assertions \b and \B require a one-character lookbehind. \A also regis-
- ters a one-character lookbehind, though it does not actually inspect
- the previous character. This is to ensure that at least one character
- from the old segment is retained when a new segment is processed. Oth-
- erwise, if there are no lookbehinds in the pattern, \A might match
+ ters a one-character lookbehind, though it does not actually inspect
+ the previous character. This is to ensure that at least one character
+ from the old segment is retained when a new segment is processed. Oth-
+ erwise, if there are no lookbehinds in the pattern, \A might match
incorrectly at the start of a second or subsequent segment.
PCRE2_INFO_MINLENGTH
- If a minimum length for matching subject strings was computed, its
- value is returned. Otherwise the returned value is 0. The value is a
- number of characters, which in UTF mode may be different from the num-
- ber of code units. The third argument should point to an uint32_t
- variable. The value is a lower bound to the length of any matching
- string. There may not be any strings of that length that do actually
+ If a minimum length for matching subject strings was computed, its
+ value is returned. Otherwise the returned value is 0. The value is a
+ number of characters, which in UTF mode may be different from the num-
+ ber of code units. The third argument should point to an uint32_t
+ variable. The value is a lower bound to the length of any matching
+ string. There may not be any strings of that length that do actually
match, but every string that does match is at least that long.
PCRE2_INFO_NAMECOUNT
@@ -2171,50 +2192,50 @@
PCRE2_INFO_NAMETABLE
PCRE2 supports the use of named as well as numbered capturing parenthe-
- ses. The names are just an additional way of identifying the parenthe-
+ ses. The names are just an additional way of identifying the parenthe-
ses, which still acquire numbers. Several convenience functions such as
- pcre2_substring_get_byname() are provided for extracting captured sub-
- strings by name. It is also possible to extract the data directly, by
- first converting the name to a number in order to access the correct
- pointers in the output vector (described with pcre2_match() below). To
- do the conversion, you need to use the name-to-number map, which is
+ pcre2_substring_get_byname() are provided for extracting captured sub-
+ strings by name. It is also possible to extract the data directly, by
+ first converting the name to a number in order to access the correct
+ pointers in the output vector (described with pcre2_match() below). To
+ do the conversion, you need to use the name-to-number map, which is
described by these three values.
- The map consists of a number of fixed-size entries. PCRE2_INFO_NAME-
- COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
- the size of each entry in code units; both of these return a uint32_t
+ The map consists of a number of fixed-size entries. PCRE2_INFO_NAME-
+ COUNT gives the number of entries, and PCRE2_INFO_NAMEENTRYSIZE gives
+ the size of each entry in code units; both of these return a uint32_t
value. The entry size depends on the length of the longest name.
PCRE2_INFO_NAMETABLE returns a pointer to the first entry of the table.
- This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit
- library, the first two bytes of each entry are the number of the cap-
+ This is a PCRE2_SPTR pointer to a block of code units. In the 8-bit
+ library, the first two bytes of each entry are the number of the cap-
turing parenthesis, most significant byte first. In the 16-bit library,
- the pointer points to 16-bit code units, the first of which contains
- the parenthesis number. In the 32-bit library, the pointer points to
- 32-bit code units, the first of which contains the parenthesis number.
+ the pointer points to 16-bit code units, the first of which contains
+ the parenthesis number. In the 32-bit library, the pointer points to
+ 32-bit code units, the first of which contains the parenthesis number.
The rest of the entry is the corresponding name, zero terminated.
- The names are in alphabetical order. If (?| is used to create multiple
- groups with the same number, as described in the section on duplicate
- subpattern numbers in the pcre2pattern page, the groups may be given
- the same name, but there is only one entry in the table. Different
+ The names are in alphabetical order. If (?| is used to create multiple
+ groups with the same number, as described in the section on duplicate
+ subpattern numbers in the pcre2pattern page, the groups may be given
+ the same name, but there is only one entry in the table. Different
names for groups of the same number are not permitted.
- Duplicate names for subpatterns with different numbers are permitted,
- but only if PCRE2_DUPNAMES is set. They appear in the table in the
- order in which they were found in the pattern. In the absence of (?|
- this is the order of increasing number; when (?| is used this is not
+ Duplicate names for subpatterns with different numbers are permitted,
+ but only if PCRE2_DUPNAMES is set. They appear in the table in the
+ order in which they were found in the pattern. In the absence of (?|
+ this is the order of increasing number; when (?| is used this is not
necessarily the case because later subpatterns may have lower numbers.
- As a simple example of the name/number table, consider the following
- pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED
+ As a simple example of the name/number table, consider the following
+ pattern after compilation by the 8-bit library (assume PCRE2_EXTENDED
is set, so white space - including newlines - is ignored):
(?<date> (?<year>(\d\d)?\d\d) -
(?<month>\d\d) - (?<day>\d\d) )
- There are four named subpatterns, so the table has four entries, and
- each entry in the table is eight bytes long. The table is as follows,
+ There are four named subpatterns, so the table has four entries, and
+ each entry in the table is eight bytes long. The table is as follows,
with non-printing bytes shows in hexadecimal, and undefined bytes shown
as ??:
@@ -2223,8 +2244,8 @@
00 04 m o n t h 00
00 02 y e a r 00 ??
- When writing code to extract data from named subpatterns using the
- name-to-number map, remember that the length of the entries is likely
+ When writing code to extract data from named subpatterns using the
+ name-to-number map, remember that the length of the entries is likely
to be different for each compiled pattern.
PCRE2_INFO_NEWLINE
@@ -2243,14 +2264,14 @@
PCRE2_INFO_SIZE
- Return the size of the compiled pattern in bytes (for all three
- libraries). The third argument should point to a size_t variable. This
- value includes the size of the general data block that precedes the
- code units of the compiled pattern itself. The value that is used when
- pcre2_compile() is getting memory in which to place the compiled pat-
- tern may be slightly larger than the value returned by this option,
- because there are cases where the code that calculates the size has to
- over-estimate. Processing a pattern with the JIT compiler does not
+ Return the size of the compiled pattern in bytes (for all three
+ libraries). The third argument should point to a size_t variable. This
+ value includes the size of the general data block that precedes the
+ code units of the compiled pattern itself. The value that is used when
+ pcre2_compile() is getting memory in which to place the compiled pat-
+ tern may be slightly larger than the value returned by this option,
+ because there are cases where the code that calculates the size has to
+ over-estimate. Processing a pattern with the JIT compiler does not
alter the value returned by this option.
@@ -2261,30 +2282,30 @@
void *user_data);
A script language that supports the use of string arguments in callouts
- might like to scan all the callouts in a pattern before running the
+ might like to scan all the callouts in a pattern before running the
match. This can be done by calling pcre2_callout_enumerate(). The first
- argument is a pointer to a compiled pattern, the second points to a
- callback function, and the third is arbitrary user data. The callback
- function is called for every callout in the pattern in the order in
+ argument is a pointer to a compiled pattern, the second points to a
+ callback function, and the third is arbitrary user data. The callback
+ function is called for every callout in the pattern in the order in
which they appear. Its first argument is a pointer to a callout enumer-
- ation block, and its second argument is the user_data value that was
- passed to pcre2_callout_enumerate(). The contents of the callout enu-
- meration block are described in the pcre2callout documentation, which
+ ation block, and its second argument is the user_data value that was
+ passed to pcre2_callout_enumerate(). The contents of the callout enu-
+ meration block are described in the pcre2callout documentation, which
also gives further details about callouts.
SERIALIZATION AND PRECOMPILING
- It is possible to save compiled patterns on disc or elsewhere, and
- reload them later, subject to a number of restrictions. The host on
- which the patterns are reloaded must be running the same version of
+ It is possible to save compiled patterns on disc or elsewhere, and
+ reload them later, subject to a number of restrictions. The host on
+ which the patterns are reloaded must be running the same version of
PCRE2, with the same code unit width, and must also have the same endi-
- anness, pointer width, and PCRE2_SIZE type. Before compiled patterns
- can be saved, they must be converted to a "serialized" form, which in
- the case of PCRE2 is really just a bytecode dump. The functions whose
- names begin with pcre2_serialize_ are used for converting to and from
- the serialized form. They are described in the pcre2serialize documen-
- tation. Note that PCRE2 serialization does not convert compiled pat-
+ anness, pointer width, and PCRE2_SIZE type. Before compiled patterns
+ can be saved, they must be converted to a "serialized" form, which in
+ the case of PCRE2 is really just a bytecode dump. The functions whose
+ names begin with pcre2_serialize_ are used for converting to and from
+ the serialized form. They are described in the pcre2serialize documen-
+ tation. Note that PCRE2 serialization does not convert compiled pat-
terns to an abstract format like Java or .NET serialization.
@@ -2298,57 +2319,57 @@
void pcre2_match_data_free(pcre2_match_data *match_data);
- Information about a successful or unsuccessful match is placed in a
- match data block, which is an opaque structure that is accessed by
- function calls. In particular, the match data block contains a vector
- of offsets into the subject string that define the matched part of the
- subject and any substrings that were captured. This is known as the
+ Information about a successful or unsuccessful match is placed in a
+ match data block, which is an opaque structure that is accessed by
+ function calls. In particular, the match data block contains a vector
+ of offsets into the subject string that define the matched part of the
+ subject and any substrings that were captured. This is known as the
ovector.
- Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
+ Before calling pcre2_match(), pcre2_dfa_match(), or pcre2_jit_match()
you must create a match data block by calling one of the creation func-
- tions above. For pcre2_match_data_create(), the first argument is the
- number of pairs of offsets in the ovector. One pair of offsets is
+ tions above. For pcre2_match_data_create(), the first argument is the
+ number of pairs of offsets in the ovector. One pair of offsets is
required to identify the string that matched the whole pattern, with an
- additional pair for each captured substring. For example, a value of 4
- creates enough space to record the matched portion of the subject plus
- three captured substrings. A minimum of at least 1 pair is imposed by
+ additional pair for each captured substring. For example, a value of 4
+ creates enough space to record the matched portion of the subject plus
+ three captured substrings. A minimum of at least 1 pair is imposed by
pcre2_match_data_create(), so it is always possible to return the over-
all matched string.
The second argument of pcre2_match_data_create() is a pointer to a gen-
- eral context, which can specify custom memory management for obtaining
+ eral context, which can specify custom memory management for obtaining
the memory for the match data block. If you are not using custom memory
management, pass NULL, which causes malloc() to be used.
- For pcre2_match_data_create_from_pattern(), the first argument is a
+ For pcre2_match_data_create_from_pattern(), the first argument is a
pointer to a compiled pattern. The ovector is created to be exactly the
right size to hold all the substrings a pattern might capture. The sec-
- ond argument is again a pointer to a general context, but in this case
+ ond argument is again a pointer to a general context, but in this case
if NULL is passed, the memory is obtained using the same allocator that
was used for the compiled pattern (custom or default).
- A match data block can be used many times, with the same or different
- compiled patterns. You can extract information from a match data block
+ A match data block can be used many times, with the same or different
+ compiled patterns. You can extract information from a match data block
after a match operation has finished, using functions that are
- described in the sections on matched strings and other match data
+ described in the sections on matched strings and other match data
below.
- When a call of pcre2_match() fails, valid data is available in the
- match block only when the error is PCRE2_ERROR_NOMATCH,
- PCRE2_ERROR_PARTIAL, or one of the error codes for an invalid UTF
+ When a call of pcre2_match() fails, valid data is available in the
+ match block only when the error is PCRE2_ERROR_NOMATCH,
+ PCRE2_ERROR_PARTIAL, or one of the error codes for an invalid UTF
string. Exactly what is available depends on the error, and is detailed
below.
- When one of the matching functions is called, pointers to the compiled
- pattern and the subject string are set in the match data block so that
- they can be referenced by the extraction functions. After running a
- match, you must not free a compiled pattern or a subject string until
- after all operations on the match data block (for that match) have
+ When one of the matching functions is called, pointers to the compiled
+ pattern and the subject string are set in the match data block so that
+ they can be referenced by the extraction functions. After running a
+ match, you must not free a compiled pattern or a subject string until
+ after all operations on the match data block (for that match) have
taken place.
- When a match data block itself is no longer needed, it should be freed
- by calling pcre2_match_data_free(). If this function is called with a
+ When a match data block itself is no longer needed, it should be freed
+ by calling pcre2_match_data_free(). If this function is called with a
NULL argument, it returns immediately, without doing anything.
@@ -2359,15 +2380,15 @@
uint32_t options, pcre2_match_data *match_data,
pcre2_match_context *mcontext);
- The function pcre2_match() is called to match a subject string against
- a compiled pattern, which is passed in the code argument. You can call
+ The function pcre2_match() is called to match a subject string against
+ a compiled pattern, which is passed in the code argument. You can call
pcre2_match() with the same code argument as many times as you like, in
- order to find multiple matches in the subject string or to match dif-
+ order to find multiple matches in the subject string or to match dif-
ferent subject strings with the same pattern.
- This function is the main matching facility of the library, and it
- operates in a Perl-like manner. For specialist use there is also an
- alternative matching function, which is described below in the section
+ This function is the main matching facility of the library, and it
+ operates in a Perl-like manner. For specialist use there is also an
+ alternative matching function, which is described below in the section
about the pcre2_dfa_match() function.
Here is an example of a simple call to pcre2_match():
@@ -2382,7 +2403,7 @@
md, /* the match data block */
NULL); /* a match context; NULL means use defaults */
- If the subject string is zero-terminated, the length can be given as
+ If the subject string is zero-terminated, the length can be given as
PCRE2_ZERO_TERMINATED. A match context must be provided if certain less
common matching parameters are to be changed. For details, see the sec-
tion on the match context above.
@@ -2389,92 +2410,92 @@
The string to be matched by pcre2_match()
- The subject string is passed to pcre2_match() as a pointer in subject,
- a length in length, and a starting offset in startoffset. The length
- and offset are in code units, not characters. That is, they are in
- bytes for the 8-bit library, 16-bit code units for the 16-bit library,
- and 32-bit code units for the 32-bit library, whether or not UTF pro-
+ The subject string is passed to pcre2_match() as a pointer in subject,
+ a length in length, and a starting offset in startoffset. The length
+ and offset are in code units, not characters. That is, they are in
+ bytes for the 8-bit library, 16-bit code units for the 16-bit library,
+ and 32-bit code units for the 32-bit library, whether or not UTF pro-
cessing is enabled.
If startoffset is greater than the length of the subject, pcre2_match()
- returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the
- search for a match starts at the beginning of the subject, and this is
+ returns PCRE2_ERROR_BADOFFSET. When the starting offset is zero, the
+ search for a match starts at the beginning of the subject, and this is
by far the most common case. In UTF-8 or UTF-16 mode, the starting off-
- set must point to the start of a character, or to the end of the sub-
- ject (in UTF-32 mode, one code unit equals one character, so all off-
- sets are valid). Like the pattern string, the subject may contain
+ set must point to the start of a character, or to the end of the sub-
+ ject (in UTF-32 mode, one code unit equals one character, so all off-
+ sets are valid). Like the pattern string, the subject may contain
binary zeros.
- A non-zero starting offset is useful when searching for another match
- in the same subject by calling pcre2_match() again after a previous
- success. Setting startoffset differs from passing over a shortened
- string and setting PCRE2_NOTBOL in the case of a pattern that begins
+ A non-zero starting offset is useful when searching for another match
+ in the same subject by calling pcre2_match() again after a previous
+ success. Setting startoffset differs from passing over a shortened
+ string and setting PCRE2_NOTBOL in the case of a pattern that begins
with any kind of lookbehind. For example, consider the pattern
\Biss\B
- which finds occurrences of "iss" in the middle of words. (\B matches
- only if the current position in the subject is not a word boundary.)
+ which finds occurrences of "iss" in the middle of words. (\B matches
+ only if the current position in the subject is not a word boundary.)
When applied to the string "Mississipi" the first call to pcre2_match()
- finds the first occurrence. If pcre2_match() is called again with just
- the remainder of the subject, namely "issipi", it does not match,
+ finds the first occurrence. If pcre2_match() is called again with just
+ the remainder of the subject, namely "issipi", it does not match,
because \B is always false at the start of the subject, which is deemed
- to be a word boundary. However, if pcre2_match() is passed the entire
+ to be a word boundary. However, if pcre2_match() is passed the entire
string again, but with startoffset set to 4, it finds the second occur-
- rence of "iss" because it is able to look behind the starting point to
+ rence of "iss" because it is able to look behind the starting point to
discover that it is preceded by a letter.
- Finding all the matches in a subject is tricky when the pattern can
+ Finding all the matches in a subject is tricky when the pattern can
match an empty string. It is possible to emulate Perl's /g behaviour by
- first trying the match again at the same offset, with the
- PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that
- fails, advancing the starting offset and trying an ordinary match
- again. There is some code that demonstrates how to do this in the
- pcre2demo sample program. In the most general case, you have to check
- to see if the newline convention recognizes CRLF as a newline, and if
- so, and the current character is CR followed by LF, advance the start-
+ first trying the match again at the same offset, with the
+ PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED options, and then if that
+ fails, advancing the starting offset and trying an ordinary match
+ again. There is some code that demonstrates how to do this in the
+ pcre2demo sample program. In the most general case, you have to check
+ to see if the newline convention recognizes CRLF as a newline, and if
+ so, and the current character is CR followed by LF, advance the start-
ing offset by two characters instead of one.
If a non-zero starting offset is passed when the pattern is anchored, a
single attempt to match at the given offset is made. This can only suc-
- ceed if the pattern does not require the match to be at the start of
- the subject. In other words, the anchoring must be the result of set-
- ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
+ ceed if the pattern does not require the match to be at the start of
+ the subject. In other words, the anchoring must be the result of set-
+ ting the PCRE2_ANCHORED option or the use of .* with PCRE2_DOTALL, not
by starting the pattern with ^ or \A.
Option bits for pcre2_match()
The unused bits of the options argument for pcre2_match() must be zero.
- The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDANCHORED,
- PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART,
- PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PAR-
+ The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDANCHORED,
+ PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY, PCRE2_NOTEMPTY_ATSTART,
+ PCRE2_NO_JIT, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD, and PCRE2_PAR-
TIAL_SOFT. Their action is described below.
- Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup-
- ported by the just-in-time (JIT) compiler. If it is set, JIT matching
- is disabled and the interpretive code in pcre2_match() is run. Apart
- from PCRE2_NO_JIT (obviously), the remaining options are supported for
+ Setting PCRE2_ANCHORED or PCRE2_ENDANCHORED at match time is not sup-
+ ported by the just-in-time (JIT) compiler. If it is set, JIT matching
+ is disabled and the interpretive code in pcre2_match() is run. Apart
+ from PCRE2_NO_JIT (obviously), the remaining options are supported for
JIT matching.
PCRE2_ANCHORED
The PCRE2_ANCHORED option limits pcre2_match() to matching at the first
- matching position. If a pattern was compiled with PCRE2_ANCHORED, or
- turned out to be anchored by virtue of its contents, it cannot be made
- unachored at matching time. Note that setting the option at match time
+ matching position. If a pattern was compiled with PCRE2_ANCHORED, or
+ turned out to be anchored by virtue of its contents, it cannot be made
+ unachored at matching time. Note that setting the option at match time
disables JIT matching.
PCRE2_ENDANCHORED
- If the PCRE2_ENDANCHORED option is set, any string that pcre2_match()
- matches must be right at the end of the subject string. Note that set-
+ If the PCRE2_ENDANCHORED option is set, any string that pcre2_match()
+ matches must be right at the end of the subject string. Note that set-
ting the option at match time disables JIT matching.
PCRE2_NOTBOL
This option specifies that first character of the subject string is not
- the beginning of a line, so the circumflex metacharacter should not
- match before it. Setting this without having set PCRE2_MULTILINE at
+ the beginning of a line, so the circumflex metacharacter should not
+ match before it. Setting this without having set PCRE2_MULTILINE at
compile time causes circumflex never to match. This option affects only
the behaviour of the circumflex metacharacter. It does not affect \A.
@@ -2481,9 +2502,9 @@
PCRE2_NOTEOL
This option specifies that the end of the subject string is not the end
- of a line, so the dollar metacharacter should not match it nor (except
- in multiline mode) a newline immediately before it. Setting this with-
- out having set PCRE2_MULTILINE at compile time causes dollar never to
+ of a line, so the dollar metacharacter should not match it nor (except
+ in multiline mode) a newline immediately before it. Setting this with-
+ out having set PCRE2_MULTILINE at compile time causes dollar never to
match. This option affects only the behaviour of the dollar metacharac-
ter. It does not affect \Z or \z.
@@ -2490,79 +2511,79 @@
PCRE2_NOTEMPTY
An empty string is not considered to be a valid match if this option is
- set. If there are alternatives in the pattern, they are tried. If all
- the alternatives match the empty string, the entire match fails. For
+ set. If there are alternatives in the pattern, they are tried. If all
+ the alternatives match the empty string, the entire match fails. For
example, if the pattern
a?b?
- is applied to a string not beginning with "a" or "b", it matches an
+ is applied to a string not beginning with "a" or "b", it matches an
empty string at the start of the subject. With PCRE2_NOTEMPTY set, this
- match is not valid, so pcre2_match() searches further into the string
+ match is not valid, so pcre2_match() searches further into the string
for occurrences of "a" or "b".
PCRE2_NOTEMPTY_ATSTART
- This is like PCRE2_NOTEMPTY, except that it locks out an empty string
+ This is like PCRE2_NOTEMPTY, except that it locks out an empty string
match only at the first matching position, that is, at the start of the
- subject plus the starting offset. An empty string match later in the
- subject is permitted. If the pattern is anchored, such a match can
+ subject plus the starting offset. An empty string match later in the
+ subject is permitted. If the pattern is anchored, such a match can
occur only if the pattern contains \K.
PCRE2_NO_JIT
- By default, if a pattern has been successfully processed by
- pcre2_jit_compile(), JIT is automatically used when pcre2_match() is
- called with options that JIT supports. Setting PCRE2_NO_JIT disables
+ By default, if a pattern has been successfully processed by
+ pcre2_jit_compile(), JIT is automatically used when pcre2_match() is
+ called with options that JIT supports. Setting PCRE2_NO_JIT disables
the use of JIT; it forces matching to be done by the interpreter.
PCRE2_NO_UTF_CHECK
When PCRE2_UTF is set at compile time, the validity of the subject as a
- UTF string is checked by default when pcre2_match() is subsequently
- called. If a non-zero starting offset is given, the check is applied
- only to that part of the subject that could be inspected during match-
- ing, and there is a check that the starting offset points to the first
- code unit of a character or to the end of the subject. If there are no
- lookbehind assertions in the pattern, the check starts at the starting
- offset. Otherwise, it starts at the length of the longest lookbehind
+ UTF string is checked by default when pcre2_match() is subsequently
+ called. If a non-zero starting offset is given, the check is applied
+ only to that part of the subject that could be inspected during match-
+ ing, and there is a check that the starting offset points to the first
+ code unit of a character or to the end of the subject. If there are no
+ lookbehind assertions in the pattern, the check starts at the starting
+ offset. Otherwise, it starts at the length of the longest lookbehind
before the starting offset, or at the start of the subject if there are
- not that many characters before the starting offset. Note that the
+ not that many characters before the starting offset. Note that the
sequences \b and \B are one-character lookbehinds.
The check is carried out before any other processing takes place, and a
- negative error code is returned if the check fails. There are several
- UTF error codes for each code unit width, corresponding to different
- problems with the code unit sequence. There are discussions about the
- validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the
+ negative error code is returned if the check fails. There are several
+ UTF error codes for each code unit width, corresponding to different
+ problems with the code unit sequence. There are discussions about the
+ validity of UTF-8 strings, UTF-16 strings, and UTF-32 strings in the
pcre2unicode page.
- If you know that your subject is valid, and you want to skip these
- checks for performance reasons, you can set the PCRE2_NO_UTF_CHECK
- option when calling pcre2_match(). You might want to do this for the
+ If you know that your subject is valid, and you want to skip these
+ checks for performance reasons, you can set the PCRE2_NO_UTF_CHECK
+ option when calling pcre2_match(). You might want to do this for the
second and subsequent calls to pcre2_match() if you are making repeated
calls to find other matches in the same subject string.
- Warning: When PCRE2_NO_UTF_CHECK is set, the effect of passing an
- invalid string as a subject, or an invalid value of startoffset, is
+ Warning: When PCRE2_NO_UTF_CHECK is set, the effect of passing an
+ invalid string as a subject, or an invalid value of startoffset, is
undefined. Your program may crash or loop indefinitely.
PCRE2_PARTIAL_HARD
PCRE2_PARTIAL_SOFT
- These options turn on the partial matching feature. A partial match
- occurs if the end of the subject string is reached successfully, but
- there are not enough subject characters to complete the match. If this
- happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set,
- matching continues by testing any remaining alternatives. Only if no
- complete match can be found is PCRE2_ERROR_PARTIAL returned instead of
- PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that
- the caller is prepared to handle a partial match, but only if no com-
+ These options turn on the partial matching feature. A partial match
+ occurs if the end of the subject string is reached successfully, but
+ there are not enough subject characters to complete the match. If this
+ happens when PCRE2_PARTIAL_SOFT (but not PCRE2_PARTIAL_HARD) is set,
+ matching continues by testing any remaining alternatives. Only if no
+ complete match can be found is PCRE2_ERROR_PARTIAL returned instead of
+ PCRE2_ERROR_NOMATCH. In other words, PCRE2_PARTIAL_SOFT specifies that
+ the caller is prepared to handle a partial match, but only if no com-
plete match can be found.
- If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
- case, if a partial match is found, pcre2_match() immediately returns
- PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
+ If PCRE2_PARTIAL_HARD is set, it overrides PCRE2_PARTIAL_SOFT. In this
+ case, if a partial match is found, pcre2_match() immediately returns
+ PCRE2_ERROR_PARTIAL, without considering any other alternatives. In
other words, when PCRE2_PARTIAL_HARD is set, a partial match is consid-
ered to be more important that an alternative complete match.
@@ -2572,38 +2593,38 @@
NEWLINE HANDLING WHEN MATCHING
- When PCRE2 is built, a default newline convention is set; this is usu-
- ally the standard convention for the operating system. The default can
- be overridden in a compile context by calling pcre2_set_newline(). It
- can also be overridden by starting a pattern string with, for example,
- (*CRLF), as described in the section on newline conventions in the
- pcre2pattern page. During matching, the newline choice affects the be-
- haviour of the dot, circumflex, and dollar metacharacters. It may also
- alter the way the match starting position is advanced after a match
+ When PCRE2 is built, a default newline convention is set; this is usu-
+ ally the standard convention for the operating system. The default can
+ be overridden in a compile context by calling pcre2_set_newline(). It
+ can also be overridden by starting a pattern string with, for example,
+ (*CRLF), as described in the section on newline conventions in the
+ pcre2pattern page. During matching, the newline choice affects the be-
+ haviour of the dot, circumflex, and dollar metacharacters. It may also
+ alter the way the match starting position is advanced after a match
failure for an unanchored pattern.
When PCRE2_NEWLINE_CRLF, PCRE2_NEWLINE_ANYCRLF, or PCRE2_NEWLINE_ANY is
- set as the newline convention, and a match attempt for an unanchored
+ set as the newline convention, and a match attempt for an unanchored
pattern fails when the current starting position is at a CRLF sequence,
- and the pattern contains no explicit matches for CR or LF characters,
- the match position is advanced by two characters instead of one, in
+ and the pattern contains no explicit matches for CR or LF characters,
+ the match position is advanced by two characters instead of one, in
other words, to after the CRLF.
The above rule is a compromise that makes the most common cases work as
- expected. For example, if the pattern is .+A (and the PCRE2_DOTALL
+ expected. For example, if the pattern is .+A (and the PCRE2_DOTALL
option is not set), it does not match the string "\r\nA" because, after
- failing at the start, it skips both the CR and the LF before retrying.
- However, the pattern [\r\n]A does match that string, because it con-
+ failing at the start, it skips both the CR and the LF before retrying.
+ However, the pattern [\r\n]A does match that string, because it con-
tains an explicit CR or LF reference, and so advances only by one char-
acter after the first failure.
An explicit match for CR of LF is either a literal appearance of one of
- those characters in the pattern, or one of the \r or \n or equivalent
+ those characters in the pattern, or one of the \r or \n or equivalent
octal or hexadecimal escape sequences. Implicit matches such as [^X] do
- not count, nor does \s, even though it includes CR and LF in the char-
+ not count, nor does \s, even though it includes CR and LF in the char-
acters that it matches.
- Notwithstanding the above, anomalous effects may still occur when CRLF
+ Notwithstanding the above, anomalous effects may still occur when CRLF
is a valid newline sequence and explicit \r or \n escapes appear in the
pattern.
@@ -2614,81 +2635,81 @@
PCRE2_SIZE *pcre2_get_ovector_pointer(pcre2_match_data *match_data);
- In general, a pattern matches a certain portion of the subject, and in
- addition, further substrings from the subject may be picked out by
- parenthesized parts of the pattern. Following the usage in Jeffrey
- Friedl's book, this is called "capturing" in what follows, and the
- phrase "capturing subpattern" or "capturing group" is used for a frag-
- ment of a pattern that picks out a substring. PCRE2 supports several
+ In general, a pattern matches a certain portion of the subject, and in
+ addition, further substrings from the subject may be picked out by
+ parenthesized parts of the pattern. Following the usage in Jeffrey
+ Friedl's book, this is called "capturing" in what follows, and the
+ phrase "capturing subpattern" or "capturing group" is used for a frag-
+ ment of a pattern that picks out a substring. PCRE2 supports several
other kinds of parenthesized subpattern that do not cause substrings to
- be captured. The pcre2_pattern_info() function can be used to find out
+ be captured. The pcre2_pattern_info() function can be used to find out
how many capturing subpatterns there are in a compiled pattern.
- You can use auxiliary functions for accessing captured substrings by
+ You can use auxiliary functions for accessing captured substrings by
number or by name, as described in sections below.
Alternatively, you can make direct use of the vector of PCRE2_SIZE val-
- ues, called the ovector, which contains the offsets of captured
- strings. It is part of the match data block. The function
- pcre2_get_ovector_pointer() returns the address of the ovector, and
+ ues, called the ovector, which contains the offsets of captured
+ strings. It is part of the match data block. The function
+ pcre2_get_ovector_pointer() returns the address of the ovector, and
pcre2_get_ovector_count() returns the number of pairs of values it con-
tains.
Within the ovector, the first in each pair of values is set to the off-
set of the first code unit of a substring, and the second is set to the
- offset of the first code unit after the end of a substring. These val-
- ues are always code unit offsets, not character offsets. That is, they
- are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit
+ offset of the first code unit after the end of a substring. These val-
+ ues are always code unit offsets, not character offsets. That is, they
+ are byte offsets in the 8-bit library, 16-bit offsets in the 16-bit
library, and 32-bit offsets in the 32-bit library.
- After a partial match (error return PCRE2_ERROR_PARTIAL), only the
- first pair of offsets (that is, ovector[0] and ovector[1]) are set.
- They identify the part of the subject that was partially matched. See
+ After a partial match (error return PCRE2_ERROR_PARTIAL), only the
+ first pair of offsets (that is, ovector[0] and ovector[1]) are set.
+ They identify the part of the subject that was partially matched. See
the pcre2partial documentation for details of partial matching.
- After a fully successful match, the first pair of offsets identifies
- the portion of the subject string that was matched by the entire pat-
- tern. The next pair is used for the first captured substring, and so
- on. The value returned by pcre2_match() is one more than the highest
- numbered pair that has been set. For example, if two substrings have
- been captured, the returned value is 3. If there are no captured sub-
+ After a fully successful match, the first pair of offsets identifies
+ the portion of the subject string that was matched by the entire pat-
+ tern. The next pair is used for the first captured substring, and so
+ on. The value returned by pcre2_match() is one more than the highest
+ numbered pair that has been set. For example, if two substrings have
+ been captured, the returned value is 3. If there are no captured sub-
strings, the return value from a successful match is 1, indicating that
just the first pair of offsets has been set.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
+ the match. For example, if the pattern (?=ab\K) is matched against
"ab", the start and end offset values for the match are 2 and 0.
- If a capturing subpattern group is matched repeatedly within a single
- match operation, it is the last portion of the subject that it matched
+ If a capturing subpattern group is matched repeatedly within a single
+ match operation, it is the last portion of the subject that it matched
that is returned.
If the ovector is too small to hold all the captured substring offsets,
- as much as possible is filled in, and the function returns a value of
- zero. If captured substrings are not of interest, pcre2_match() may be
+ as much as possible is filled in, and the function returns a value of
+ zero. If captured substrings are not of interest, pcre2_match() may be
called with a match data block whose ovector is of minimum length (that
is, one pair).
- It is possible for capturing subpattern number n+1 to match some part
+ It is possible for capturing subpattern number n+1 to match some part
of the subject when subpattern n has not been used at all. For example,
- if the string "abc" is matched against the pattern (a|(z))(bc) the
+ if the string "abc" is matched against the pattern (a|(z))(bc) the
return from the function is 4, and subpatterns 1 and 3 are matched, but
- 2 is not. When this happens, both values in the offset pairs corre-
+ 2 is not. When this happens, both values in the offset pairs corre-
sponding to unused subpatterns are set to PCRE2_UNSET.
- Offset values that correspond to unused subpatterns at the end of the
- expression are also set to PCRE2_UNSET. For example, if the string
+ Offset values that correspond to unused subpatterns at the end of the
+ expression are also set to PCRE2_UNSET. For example, if the string
"abc" is matched against the pattern (abc)(x(yz)?)? subpatterns 2 and 3
- are not matched. The return from the function is 2, because the high-
+ are not matched. The return from the function is 2, because the high-
est used capturing subpattern number is 1. The offsets for for the sec-
- ond and third capturing subpatterns (assuming the vector is large
+ ond and third capturing subpatterns (assuming the vector is large
enough, of course) are set to PCRE2_UNSET.
Elements in the ovector that do not correspond to capturing parentheses
in the pattern are never changed. That is, if a pattern contains n cap-
turing parentheses, no more than ovector[0] to ovector[2n+1] are set by
- pcre2_match(). The other elements retain whatever values they previ-
+ pcre2_match(). The other elements retain whatever values they previ-
ously had.
@@ -2698,55 +2719,55 @@
PCRE2_SIZE pcre2_get_startchar(pcre2_match_data *match_data);
- As well as the offsets in the ovector, other information about a match
- is retained in the match data block and can be retrieved by the above
- functions in appropriate circumstances. If they are called at other
+ As well as the offsets in the ovector, other information about a match
+ is retained in the match data block and can be retrieved by the above
+ functions in appropriate circumstances. If they are called at other
times, the result is undefined.
- After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
+ After a successful match, a partial match (PCRE2_ERROR_PARTIAL), or a
failure to match (PCRE2_ERROR_NOMATCH), a (*MARK), (*PRUNE), or (*THEN)
- name may be available. The function pcre2_get_mark() can be called to
- access this name. The same function applies to all three verbs. It
+ name may be available. The function pcre2_get_mark() can be called to
+ access this name. The same function applies to all three verbs. It
returns a pointer to the zero-terminated name, which is within the com-
piled pattern. If no name is available, NULL is returned. The length of
- the name (excluding the terminating zero) is stored in the code unit
- that precedes the name. You should use this length instead of relying
+ the name (excluding the terminating zero) is stored in the code unit
+ that precedes the name. You should use this length instead of relying
on the terminating zero if the name might contain a binary zero.
- After a successful match, the name that is returned is the last
- (*MARK), (*PRUNE), or (*THEN) name encountered on the matching path
- through the pattern. Instances of (*PRUNE) and (*THEN) without names
- are ignored. Thus, for example, if the matching path contains
- (*MARK:A)(*PRUNE), the name "A" is returned. After a "no match" or a
- partial match, the last encountered name is returned. For example,
+ After a successful match, the name that is returned is the last
+ (*MARK), (*PRUNE), or (*THEN) name encountered on the matching path
+ through the pattern. Instances of (*PRUNE) and (*THEN) without names
+ are ignored. Thus, for example, if the matching path contains
+ (*MARK:A)(*PRUNE), the name "A" is returned. After a "no match" or a
+ partial match, the last encountered name is returned. For example,
consider this pattern:
^(*MARK:A)((*MARK:B)a|b)c
- When it matches "bc", the returned name is A. The B mark is "seen" in
- the first branch of the group, but it is not on the matching path. On
- the other hand, when this pattern fails to match "bx", the returned
+ When it matches "bc", the returned name is A. The B mark is "seen" in
+ the first branch of the group, but it is not on the matching path. On
+ the other hand, when this pattern fails to match "bx", the returned
name is B.
- 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
+ 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
engine. This check fails for "bx", causing a match failure without see-
ing any marks. You can disable the start-of-match optimizations by set-
ting the PCRE2_NO_START_OPTIMIZE option for pcre2_compile() or 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.
@@ -2753,14 +2774,14 @@
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
@@ -2769,20 +2790,20 @@
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
@@ -2796,15 +2817,15 @@
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
@@ -2817,14 +2838,14 @@
PCRE2_ERROR_INTERNAL
- An unexpected internal error has occurred. This error could be caused
+ An unexpected internal error has occurred. This error could be caused
by a bug in PCRE2 or by overwriting of the compiled pattern.
PCRE2_ERROR_JIT_STACKLIMIT
- This error is returned when a pattern that was successfully studied
- using JIT is being matched, but the memory available for the just-in-
- time processing stack is not large enough. See the pcre2jit documenta-
+ This error is returned when a pattern that was successfully studied
+ using JIT is being matched, but the memory available for the just-in-
+ time processing stack is not large enough. See the pcre2jit documenta-
tion for more details.
PCRE2_ERROR_MATCHLIMIT
@@ -2833,10 +2854,10 @@
PCRE2_ERROR_NOMEMORY
- If a pattern contains many nested backtracking points, heap memory is
- used to remember them. This error is given when the memory allocation
- function (default or custom) fails. Note that a different error,
- PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
+ If a pattern contains many nested backtracking points, heap memory is
+ used to remember them. This error is given when the memory allocation
+ function (default or custom) fails. Note that a different error,
+ PCRE2_ERROR_HEAPLIMIT, is given if the amount of memory needed exceeds
the heap limit.
PCRE2_ERROR_NULL
@@ -2845,12 +2866,12 @@
PCRE2_ERROR_RECURSELOOP
- This error is returned when pcre2_match() detects a recursion loop
- within the pattern. Specifically, it means that either the whole pat-
+ This error is returned when pcre2_match() detects a recursion loop
+ within the pattern. Specifically, it means that either the whole pat-
tern or a subpattern has been called recursively for the second time at
- the same position in the subject string. Some simple patterns that
- might do this are detected and faulted at compile time, but more com-
- plicated cases, in particular mutual recursions between two different
+ the same position in the subject string. Some simple patterns that
+ might do this are detected and faulted at compile time, but more com-
+ plicated cases, in particular mutual recursions between two different
subpatterns, cannot be detected until matching is attempted.
@@ -2859,20 +2880,20 @@
int pcre2_get_error_message(int errorcode, PCRE2_UCHAR *buffer,
PCRE2_SIZE bufflen);
- A text message for an error code from any PCRE2 function (compile,
- match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
- sage(). The code is passed as the first argument, with the remaining
- two arguments specifying a code unit buffer and its length in code
- units, into which the text message is placed. The message is returned
- in code units of the appropriate width for the library that is being
+ A text message for an error code from any PCRE2 function (compile,
+ match, or auxiliary) can be obtained by calling pcre2_get_error_mes-
+ sage(). The code is passed as the first argument, with the remaining
+ two arguments specifying a code unit buffer and its length in code
+ units, into which the text message is placed. The message is returned
+ in code units of the appropriate width for the library that is being
used.
- The returned message is terminated with a trailing zero, and the func-
- tion returns the number of code units used, excluding the trailing
+ The returned message is terminated with a trailing zero, and the func-
+ tion returns the number of code units used, excluding the trailing
zero. If the error number is unknown, the negative error code
- PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes-
- sage is truncated (but still with a trailing zero), and the negative
- error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are
+ PCRE2_ERROR_BADDATA is returned. If the buffer is too small, the mes-
+ sage is truncated (but still with a trailing zero), and the negative
+ error code PCRE2_ERROR_NOMEMORY is returned. None of the messages are
very long; a buffer size of 120 code units is ample.
@@ -2891,39 +2912,39 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- Captured substrings can be accessed directly by using the ovector as
+ Captured substrings can be accessed directly by using the ovector as
described above. For convenience, auxiliary functions are provided for
- extracting captured substrings as new, separate, zero-terminated
+ extracting captured substrings as new, separate, zero-terminated
strings. A substring that contains a binary zero is correctly extracted
- and has a further zero added on the end, but the result is not, of
+ and has a further zero added on the end, but the result is not, of
course, a C string.
The functions in this section identify substrings by number. The number
zero refers to the entire matched substring, with higher numbers refer-
- ring to substrings captured by parenthesized groups. After a partial
- match, only substring zero is available. An attempt to extract any
- other substring gives the error PCRE2_ERROR_PARTIAL. The next section
+ ring to substrings captured by parenthesized groups. After a partial
+ match, only substring zero is available. An attempt to extract any
+ other substring gives the error PCRE2_ERROR_PARTIAL. The next section
describes similar functions for extracting captured substrings by name.
- If a pattern uses the \K escape sequence within a positive assertion,
+ If a pattern uses the \K escape sequence within a positive assertion,
the reported start of a successful match can be greater than the end of
- the match. For example, if the pattern (?=ab\K) is matched against
- "ab", the start and end offset values for the match are 2 and 0. In
- this situation, calling these functions with a zero substring number
+ the match. For example, if the pattern (?=ab\K) is matched against
+ "ab", the start and end offset values for the match are 2 and 0. In
+ this situation, calling these functions with a zero substring number
extracts a zero-length empty string.
- You can find the length in code units of a captured substring without
- extracting it by calling pcre2_substring_length_bynumber(). The first
- argument is a pointer to the match data block, the second is the group
- number, and the third is a pointer to a variable into which the length
- is placed. If you just want to know whether or not the substring has
+ You can find the length in code units of a captured substring without
+ extracting it by calling pcre2_substring_length_bynumber(). The first
+ argument is a pointer to the match data block, the second is the group
+ number, and the third is a pointer to a variable into which the length
+ is placed. If you just want to know whether or not the substring has
been captured, you can pass the third argument as NULL.
- The pcre2_substring_copy_bynumber() function copies a captured sub-
- string into a supplied buffer, whereas pcre2_substring_get_bynumber()
- copies it into new memory, obtained using the same memory allocation
- function that was used for the match data block. The first two argu-
- ments of these functions are a pointer to the match data block and a
+ The pcre2_substring_copy_bynumber() function copies a captured sub-
+ string into a supplied buffer, whereas pcre2_substring_get_bynumber()
+ copies it into new memory, obtained using the same memory allocation
+ function that was used for the match data block. The first two argu-
+ ments of these functions are a pointer to the match data block and a
capturing group number.
The final arguments of pcre2_substring_copy_bynumber() are a pointer to
@@ -2932,25 +2953,25 @@
for the extracted substring, excluding the terminating zero.
For pcre2_substring_get_bynumber() the third and fourth arguments point
- to variables that are updated with a pointer to the new memory and the
- number of code units that comprise the substring, again excluding the
- terminating zero. When the substring is no longer needed, the memory
+ to variables that are updated with a pointer to the new memory and the
+ number of code units that comprise the substring, again excluding the
+ terminating zero. When the substring is no longer needed, the memory
should be freed by calling pcre2_substring_free().
- The return value from all these functions is zero for success, or a
- negative error code. If the pattern match failed, the match failure
- code is returned. If a substring number greater than zero is used
- after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
+ The return value from all these functions is zero for success, or a
+ negative error code. If the pattern match failed, the match failure
+ code is returned. If a substring number greater than zero is used
+ after a partial match, PCRE2_ERROR_PARTIAL is returned. Other possible
error codes are:
PCRE2_ERROR_NOMEMORY
- The buffer was too small for pcre2_substring_copy_bynumber(), or the
+ The buffer was too small for pcre2_substring_copy_bynumber(), or the
attempt to get memory failed for pcre2_substring_get_bynumber().
PCRE2_ERROR_NOSUBSTRING
- There is no substring with that number in the pattern, that is, the
+ There is no substring with that number in the pattern, that is, the
number is greater than the number of capturing parentheses.
PCRE2_ERROR_UNAVAILABLE
@@ -2961,8 +2982,8 @@
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.
@@ -2973,32 +2994,32 @@
void pcre2_substring_list_free(PCRE2_SPTR *list);
- The pcre2_substring_list_get() function extracts all available sub-
- strings and builds a list of pointers to them. It also (optionally)
- builds a second list that contains their lengths (in code units),
+ The pcre2_substring_list_get() function extracts all available sub-
+ strings and builds a list of pointers to them. It also (optionally)
+ builds a second list that contains their lengths (in code units),
excluding a terminating zero that is added to each of them. All this is
done in a single block of memory that is obtained using the same memory
allocation function that was used to get the match data block.
- This function must be called only after a successful match. If called
+ This function must be called only after a successful match. If called
after a partial match, the error code PCRE2_ERROR_PARTIAL is returned.
- The address of the memory block is returned via listptr, which is also
+ The address of the memory block is returned via listptr, which is also
the start of the list of string pointers. The end of the list is marked
- by a NULL pointer. The address of the list of lengths is returned via
- lengthsptr. If your strings do not contain binary zeros and you do not
+ by a NULL pointer. The address of the list of lengths is returned via
+ lengthsptr. If your strings do not contain binary zeros and you do not
therefore need the lengths, you may supply NULL as the lengthsptr argu-
- ment to disable the creation of a list of lengths. The yield of the
- function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
- ory block could not be obtained. When the list is no longer needed, it
+ ment to disable the creation of a list of lengths. The yield of the
+ function is zero if all went well, or PCRE2_ERROR_NOMEMORY if the mem-
+ ory block could not be obtained. When the list is no longer needed, it
should be freed by calling pcre2_substring_list_free().
If this function encounters a substring that is unset, which can happen
- when capturing subpattern number n+1 matches some part of the subject,
- but subpattern n has not been used at all, it returns an empty string.
- This can be distinguished from a genuine zero-length substring by
+ when capturing subpattern number n+1 matches some part of the subject,
+ but subpattern n has not been used at all, it returns an empty string.
+ This can be distinguished from a genuine zero-length substring by
inspecting the appropriate offset in the ovector, which contain
- PCRE2_UNSET for unset substrings, or by calling pcre2_sub-
+ PCRE2_UNSET for unset substrings, or by calling pcre2_sub-
string_length_bynumber().
@@ -3018,39 +3039,39 @@
void pcre2_substring_free(PCRE2_UCHAR *buffer);
- To extract a substring by name, you first have to find associated num-
+ To extract a substring by name, you first have to find associated num-
ber. For example, for this pattern:
(a+)b(?<xxx>\d+)...
the number of the subpattern called "xxx" is 2. If the name is known to
- be unique (PCRE2_DUPNAMES was not set), you can find the number from
+ be unique (PCRE2_DUPNAMES was not set), you can find the number from
the name by calling pcre2_substring_number_from_name(). The first argu-
- ment is the compiled pattern, and the second is the name. The yield of
+ ment is the compiled pattern, and the second is the name. The yield of
the function is the subpattern number, PCRE2_ERROR_NOSUBSTRING if there
- is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
- there is more than one subpattern of that name. Given the number, you
- can extract the substring directly from the ovector, or use one of the
+ is no subpattern of that name, or PCRE2_ERROR_NOUNIQUESUBSTRING if
+ there is more than one subpattern of that name. Given the number, you
+ can extract the substring directly from the ovector, or use one of the
"bynumber" functions described above.
- For convenience, there are also "byname" functions that correspond to
- the "bynumber" functions, the only difference being that the second
- argument is a name instead of a number. If PCRE2_DUPNAMES is set and
+ For convenience, there are also "byname" functions that correspond to
+ the "bynumber" functions, the only difference being that the second
+ argument is a name instead of a number. If PCRE2_DUPNAMES is set and
there are duplicate names, these functions scan all the groups with the
given name, and return the first named string that is set.
- If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
- returned. If all groups with the name have numbers that are greater
- than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
- returned. If there is at least one group with a slot in the ovector,
+ If there are no groups with the given name, PCRE2_ERROR_NOSUBSTRING is
+ returned. If all groups with the name have numbers that are greater
+ than the number of slots in the ovector, PCRE2_ERROR_UNAVAILABLE is
+ returned. If there is at least one group with a slot in the ovector,
but no group is found to be set, PCRE2_ERROR_UNSET is returned.
Warning: If the pattern uses the (?| feature to set up multiple subpat-
- terns with the same number, as described in the section on duplicate
- subpattern numbers in the pcre2pattern page, you cannot use names to
- distinguish the different subpatterns, because names are not included
- in the compiled code. The matching process uses only numbers. For this
- reason, the use of different names for subpatterns of the same number
+ terns with the same number, as described in the section on duplicate
+ subpattern numbers in the pcre2pattern page, you cannot use names to
+ distinguish the different subpatterns, because names are not included
+ in the compiled code. The matching process uses only numbers. For this
+ reason, the use of different names for subpatterns of the same number
causes an error at compile time.
@@ -3063,45 +3084,45 @@
PCRE2_SIZE rlength, PCRE2_UCHAR *outputbufferP,
PCRE2_SIZE *outlengthptr);
- This function calls pcre2_match() and then makes a copy of the subject
- string in outputbuffer, replacing the part that was matched with the
- replacement string, whose length is supplied in rlength. This can be
+ This function calls pcre2_match() and then makes a copy of the subject
+ string in outputbuffer, replacing the part that was matched with the
+ replacement string, whose length is supplied in rlength. This can be
given as PCRE2_ZERO_TERMINATED for a zero-terminated string. Matches in
- which a \K item in a lookahead in the pattern causes the match to end
- before it starts are not supported, and give rise to an error return.
+ 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 lookbehind causes the
- match to start earlier than the point that was reached in the previous
+ 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.
- The outlengthptr argument must point to a variable that contains the
- length, in code units, of the output buffer. If the function is suc-
- cessful, the value is updated to contain the length of the new string,
+ The outlengthptr argument must point to a variable that contains the
+ length, in code units, of the output buffer. If the function is suc-
+ cessful, the value is updated to contain the length of the new string,
excluding the trailing zero that is automatically added.
- If the function is not successful, the value set via outlengthptr
- depends on the type of error. For syntax errors in the replacement
- string, the value is the offset in the replacement string where the
- error was detected. For other errors, the value is PCRE2_UNSET by
- default. This includes the case of the output buffer being too small,
- unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which
- case the value is the minimum length needed, including space for the
- trailing zero. Note that in order to compute the required length,
- pcre2_substitute() has to simulate all the matching and copying,
+ If the function is not successful, the value set via outlengthptr
+ depends on the type of error. For syntax errors in the replacement
+ string, the value is the offset in the replacement string where the
+ error was detected. For other errors, the value is PCRE2_UNSET by
+ default. This includes the case of the output buffer being too small,
+ unless PCRE2_SUBSTITUTE_OVERFLOW_LENGTH is set (see below), in which
+ case the value is the minimum length needed, including space for the
+ trailing zero. Note that in order to compute the required length,
+ pcre2_substitute() has to simulate all the matching and copying,
instead of giving an error return as soon as the buffer overflows. Note
also that the length is in code units, not bytes.
- In the replacement string, which is interpreted as a UTF string in UTF
- mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK
+ In the replacement string, which is interpreted as a UTF string in UTF
+ mode, and is checked for UTF validity unless the PCRE2_NO_UTF_CHECK
option is set, a dollar character is an escape character that can spec-
- ify the insertion of characters from capturing groups or (*MARK),
- (*PRUNE), or (*THEN) items in the pattern. The following forms are
+ ify the insertion of characters from capturing groups or (*MARK),
+ (*PRUNE), or (*THEN) items in the pattern. The following forms are
always recognized:
$$ insert a dollar character
@@ -3108,19 +3129,19 @@
$<n> or ${<n>} insert the contents of group <n>
$*MARK or ${*MARK} insert a (*MARK), (*PRUNE), or (*THEN) name
- Either a group number or a group name can be given for <n>. Curly
- brackets are required only if the following character would be inter-
+ Either a group number or a group name can be given for <n>. Curly
+ brackets are required only if the following character would be inter-
preted as part of the number or name. The number may be zero to include
- the entire matched string. For example, if the pattern a(b)c is
- matched with "=abc=" and the replacement string "+$1$0$1+", the result
+ the entire matched string. For example, if the pattern a(b)c is
+ matched with "=abc=" and the replacement string "+$1$0$1+", the result
is "=+babcb+=".
$*MARK inserts the name from the last encountered (*MARK), (*PRUNE), or
- (*THEN) on the matching path that has a name. (*MARK) must always
- include a name, but (*PRUNE) and (*THEN) need not. For example, in the
- case of (*MARK:A)(*PRUNE) the name inserted is "A", but for
- (*MARK:A)(*PRUNE:B) the relevant name is "B". This facility can be
- used to perform simple simultaneous substitutions, as this pcre2test
+ (*THEN) on the matching path that has a name. (*MARK) must always
+ include a name, but (*PRUNE) and (*THEN) need not. For example, in the
+ case of (*MARK:A)(*PRUNE) the name inserted is "A", but for
+ (*MARK:A)(*PRUNE:B) the relevant name is "B". This facility can be
+ used to perform simple simultaneous substitutions, as this pcre2test
example shows:
/(*MARK:pear)apple|(*MARK:orange)lemon/g,replace=${*MARK}
@@ -3127,19 +3148,19 @@
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:
@@ -3147,87 +3168,87 @@
ABC ABC ABC ABC\=offset=3,offset_limit=12
2: ABC A!C A!C ABC
- When continuing with global substitutions after matching a substring
+ When continuing with global substitutions after matching a substring
with zero length, an attempt to find a non-empty match at the same off-
set is performed. If this is not successful, the offset is advanced by
one character except when CRLF is a valid newline sequence and the next
- two characters are CR, LF. In this case, the offset is advanced by two
+ two characters are CR, LF. In this case, the offset is advanced by two
characters.
- PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
+ PCRE2_SUBSTITUTE_OVERFLOW_LENGTH changes what happens when the output
buffer is too small. The default action is to return PCRE2_ERROR_NOMEM-
- ORY immediately. If this option is set, however, pcre2_substitute()
+ ORY immediately. If this option is set, however, pcre2_substitute()
continues to go through the motions of matching and substituting (with-
- out, of course, writing anything) in order to compute the size of buf-
- fer that is needed. This value is passed back via the outlengthptr
- variable, with the result of the function still being
+ out, of course, writing anything) in order to compute the size of buf-
+ fer that is needed. This value is passed back via the outlengthptr
+ variable, with the result of the function still being
PCRE2_ERROR_NOMEMORY.
- Passing a buffer size of zero is a permitted way of finding out how
- much memory is needed for given substitution. However, this does mean
+ Passing a buffer size of zero is a permitted way of finding out how
+ much memory is needed for given substitution. However, this does mean
that the entire operation is carried out twice. Depending on the appli-
- cation, it may be more efficient to allocate a large buffer and free
- the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
+ cation, it may be more efficient to allocate a large buffer and free
+ the excess afterwards, instead of using PCRE2_SUBSTITUTE_OVER-
FLOW_LENGTH.
- PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups
- that do not appear in the pattern to be treated as unset groups. This
- option should be used with care, because it means that a typo in a
- group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING
+ PCRE2_SUBSTITUTE_UNKNOWN_UNSET causes references to capturing groups
+ that do not appear in the pattern to be treated as unset groups. This
+ option should be used with care, because it means that a typo in a
+ group name or number no longer causes the PCRE2_ERROR_NOSUBSTRING
error.
- PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including
+ PCRE2_SUBSTITUTE_UNSET_EMPTY causes unset capturing groups (including
unknown groups when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set) to be
- treated as empty strings when inserted as described above. If this
- option is not set, an attempt to insert an unset group causes the
- PCRE2_ERROR_UNSET error. This option does not influence the extended
+ treated as empty strings when inserted as described above. If this
+ option is not set, an attempt to insert an unset group causes the
+ PCRE2_ERROR_UNSET error. This option does not influence the extended
substitution syntax described below.
- PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
- replacement string. Without this option, only the dollar character is
- special, and only the group insertion forms listed above are valid.
+ PCRE2_SUBSTITUTE_EXTENDED causes extra processing to be applied to the
+ replacement string. Without this option, only the dollar character is
+ special, and only the group insertion forms listed above are valid.
When PCRE2_SUBSTITUTE_EXTENDED is set, two things change:
- Firstly, backslash in a replacement string is interpreted as an escape
+ Firstly, backslash in a replacement string is interpreted as an escape
character. The usual forms such as \n or \x{ddd} can be used to specify
- particular character codes, and backslash followed by any non-alphanu-
- meric character quotes that character. Extended quoting can be coded
+ particular character codes, and backslash followed by any non-alphanu-
+ meric character quotes that character. Extended quoting can be coded
using \Q...\E, exactly as in pattern strings.
- There are also four escape sequences for forcing the case of inserted
- letters. The insertion mechanism has three states: no case forcing,
+ There are also four escape sequences for forcing the case of inserted
+ letters. The insertion mechanism has three states: no case forcing,
force upper case, and force lower case. The escape sequences change the
current state: \U and \L change to upper or lower case forcing, respec-
- tively, and \E (when not terminating a \Q quoted sequence) reverts to
- no case forcing. The sequences \u and \l force the next character (if
- it is a letter) to upper or lower case, respectively, and then the
+ tively, and \E (when not terminating a \Q quoted sequence) reverts to
+ no case forcing. The sequences \u and \l force the next character (if
+ it is a letter) to upper or lower case, respectively, and then the
state automatically reverts to no case forcing. Case forcing applies to
all inserted characters, including those from captured groups and let-
ters within \Q...\E quoted sequences.
Note that case forcing sequences such as \U...\E do not nest. For exam-
- ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
+ ple, the result of processing "\Uaa\LBB\Ecc\E" is "AAbbcc"; the final
\E has no effect.
- The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
- flexibility to group substitution. The syntax is similar to that used
+ The second effect of setting PCRE2_SUBSTITUTE_EXTENDED is to add more
+ flexibility to group substitution. The syntax is similar to that used
by Bash:
${<n>:-<string>}
${<n>:+<string1>:<string2>}
- As before, <n> may be a group number or a name. The first form speci-
- fies a default value. If group <n> is set, its value is inserted; if
- not, <string> is expanded and the result inserted. The second form
- specifies strings that are expanded and inserted when group <n> is set
- or unset, respectively. The first form is just a convenient shorthand
+ As before, <n> may be a group number or a name. The first form speci-
+ fies a default value. If group <n> is set, its value is inserted; if
+ not, <string> is expanded and the result inserted. The second form
+ specifies strings that are expanded and inserted when group <n> is set
+ or unset, respectively. The first form is just a convenient shorthand
for
${<n>:+${<n>}:<string>}
- Backslash can be used to escape colons and closing curly brackets in
- the replacement strings. A change of the case forcing state within a
- replacement string remains in force afterwards, as shown in this
+ Backslash can be used to escape colons and closing curly brackets in
+ the replacement strings. A change of the case forcing state within a
+ replacement string remains in force afterwards, as shown in this
pcre2test example:
/(some)?(body)/substitute_extended,replace=${1:+\U:\L}HeLLo
@@ -3236,16 +3257,16 @@
somebody
1: HELLO
- The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
- substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause
+ The PCRE2_SUBSTITUTE_UNSET_EMPTY option does not affect these extended
+ substitutions. However, PCRE2_SUBSTITUTE_UNKNOWN_UNSET does cause
unknown groups in the extended syntax forms to be treated as unset.
- If successful, pcre2_substitute() returns the number of replacements
+ If successful, pcre2_substitute() returns the number of replacements
that were made. This may be zero if no matches were found, and is never
greater than 1 unless PCRE2_SUBSTITUTE_GLOBAL is set.
In the event of an error, a negative error code is returned. Except for
- PCRE2_ERROR_NOMATCH (which is never returned), errors from
+ PCRE2_ERROR_NOMATCH (which is never returned), errors from
pcre2_match() are passed straight back.
PCRE2_ERROR_NOSUBSTRING is returned for a non-existent substring inser-
@@ -3252,26 +3273,26 @@
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)
+ ing an unknown substring when PCRE2_SUBSTITUTE_UNKNOWN_UNSET is set)
when the simple (non-extended) syntax is used and PCRE2_SUBSTI-
TUTE_UNSET_EMPTY is not set.
- PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
+ PCRE2_ERROR_NOMEMORY is returned if the output buffer is not big
enough. If the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set, the size
- of buffer that is needed is returned via outlengthptr. Note that this
+ of buffer that is needed is returned via outlengthptr. Note that this
does not happen by default.
- PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
+ PCRE2_ERROR_BADREPLACEMENT is used for miscellaneous syntax errors in
the replacement string, with more particular errors being
- PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
- MISSINGBRACE (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
+ PCRE2_ERROR_BADREPESCAPE (invalid escape sequence), PCRE2_ERROR_REP-
+ MISSINGBRACE (closing curly bracket not found), PCRE2_ERROR_BADSUBSTI-
TUTION (syntax error in extended group substitution), and
- PCRE2_ERROR_BADSUBSPATTERN (the pattern match ended before it started
- or the match started earlier than the current position in the subject,
+ 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 used in an assertion).
As for all PCRE2 errors, a text message that describes the error can be
- obtained by calling the pcre2_get_error_message() function (see
+ obtained by calling the pcre2_get_error_message() function (see
"Obtaining a textual error message" above).
@@ -3280,56 +3301,56 @@
int pcre2_substring_nametable_scan(const pcre2_code *code,
PCRE2_SPTR name, PCRE2_SPTR *first, PCRE2_SPTR *last);
- When a pattern is compiled with the PCRE2_DUPNAMES option, names for
- subpatterns are not required to be unique. Duplicate names are always
- allowed for subpatterns with the same number, created by using the (?|
- feature. Indeed, if such subpatterns are named, they are required to
+ When a pattern is compiled with the PCRE2_DUPNAMES option, names for
+ subpatterns are not required to be unique. Duplicate names are always
+ allowed for subpatterns with the same number, created by using the (?|
+ feature. Indeed, if such subpatterns are named, they are required to
use the same names.
Normally, patterns with duplicate names are such that in any one match,
- only one of the named subpatterns participates. An example is shown in
+ only one of the named subpatterns participates. An example is shown in
the pcre2pattern documentation.
- When duplicates are present, pcre2_substring_copy_byname() and
- pcre2_substring_get_byname() return the first substring corresponding
- to the given name that is set. Only if none are set is
- PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name()
+ When duplicates are present, pcre2_substring_copy_byname() and
+ pcre2_substring_get_byname() return the first substring corresponding
+ to the given name that is set. Only if none are set is
+ PCRE2_ERROR_UNSET is returned. The pcre2_substring_number_from_name()
function returns the error PCRE2_ERROR_NOUNIQUESUBSTRING when there are
duplicate names.
- If you want to get full details of all captured substrings for a given
- name, you must use the pcre2_substring_nametable_scan() function. The
- first argument is the compiled pattern, and the second is the name. If
- the third and fourth arguments are NULL, the function returns a group
+ If you want to get full details of all captured substrings for a given
+ name, you must use the pcre2_substring_nametable_scan() function. The
+ first argument is the compiled pattern, and the second is the name. If
+ the third and fourth arguments are NULL, the function returns a group
number for a unique name, or PCRE2_ERROR_NOUNIQUESUBSTRING otherwise.
When the third and fourth arguments are not NULL, they must be pointers
- to variables that are updated by the function. After it has run, they
+ to variables that are updated by the function. After it has run, they
point to the first and last entries in the name-to-number table for the
- given name, and the function returns the length of each entry in code
- units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
+ given name, and the function returns the length of each entry in code
+ units. In both cases, PCRE2_ERROR_NOSUBSTRING is returned if there are
no entries for the given name.
The format of the name table is described above in the section entitled
- Information about a pattern. Given all the relevant entries for the
- name, you can extract each of their numbers, and hence the captured
+ Information about a pattern. Given all the relevant entries for the
+ name, you can extract each of their numbers, and hence the captured
data.
FINDING ALL POSSIBLE MATCHES AT ONE POSITION
- The traditional matching function uses a similar algorithm to Perl,
- which stops when it finds the first match at a given point in the sub-
+ The traditional matching function uses a similar algorithm to Perl,
+ which stops when it finds the first match at a given point in the sub-
ject. If you want to find all possible matches, or the longest possible
- match at a given position, consider using the alternative matching
- function (see below) instead. If you cannot use the alternative func-
+ match at a given position, consider using the alternative matching
+ function (see below) instead. If you cannot use the alternative func-
tion, you can kludge it up by making use of the callout facility, which
is described in the pcre2callout documentation.
What you have to do is to insert a callout right at the end of the pat-
- tern. When your callout function is called, extract and save the cur-
- rent matched substring. Then return 1, which forces pcre2_match() to
- backtrack and try other alternatives. Ultimately, when it runs out of
+ tern. When your callout function is called, extract and save the cur-
+ rent matched substring. Then return 1, which forces pcre2_match() to
+ backtrack and try other alternatives. Ultimately, when it runs out of
matches, pcre2_match() will yield PCRE2_ERROR_NOMATCH.
@@ -3341,26 +3362,26 @@
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():
@@ -3380,45 +3401,45 @@
Option bits for pcre_dfa_match()
- The unused bits of the options argument for pcre2_dfa_match() must be
- zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDAN-
- CHORED, PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY,
+ The unused bits of the options argument for pcre2_dfa_match() must be
+ zero. The only bits that may be set are PCRE2_ANCHORED, PCRE2_ENDAN-
+ CHORED, PCRE2_NOTBOL, PCRE2_NOTEOL, PCRE2_NOTEMPTY,
PCRE2_NOTEMPTY_ATSTART, PCRE2_NO_UTF_CHECK, PCRE2_PARTIAL_HARD,
- PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but
- the last four of these are exactly the same as for pcre2_match(), so
+ PCRE2_PARTIAL_SOFT, PCRE2_DFA_SHORTEST, and PCRE2_DFA_RESTART. All but
+ the last four of these are exactly the same as for pcre2_match(), so
their description is not repeated here.
PCRE2_PARTIAL_HARD
PCRE2_PARTIAL_SOFT
- These have the same general effect as they do for pcre2_match(), but
- the details are slightly different. When PCRE2_PARTIAL_HARD is set for
- pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
+ These have the same general effect as they do for pcre2_match(), but
+ the details are slightly different. When PCRE2_PARTIAL_HARD is set for
+ pcre2_dfa_match(), it returns PCRE2_ERROR_PARTIAL if the end of the
subject is reached and there is still at least one matching possibility
that requires additional characters. This happens even if some complete
- matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
- return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
- if the end of the subject is reached, there have been no complete
+ matches have already been found. When PCRE2_PARTIAL_SOFT is set, the
+ return code PCRE2_ERROR_NOMATCH is converted into PCRE2_ERROR_PARTIAL
+ if the end of the subject is reached, there have been no complete
matches, but there is still at least one matching possibility. The por-
- tion of the string that was inspected when the longest partial match
+ tion of the string that was inspected when the longest partial match
was found is set as the first matching string in both cases. There is a
- more detailed discussion of partial and multi-segment matching, with
+ more detailed discussion of partial and multi-segment matching, with
examples, in the pcre2partial documentation.
PCRE2_DFA_SHORTEST
- Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
+ Setting the PCRE2_DFA_SHORTEST option causes the matching algorithm to
stop as soon as it has found one match. Because of the way the alterna-
- tive algorithm works, this is necessarily the shortest possible match
+ tive algorithm works, this is necessarily the shortest possible match
at the first possible matching point in the subject string.
PCRE2_DFA_RESTART
- When pcre2_dfa_match() returns a partial match, it is possible to call
+ When pcre2_dfa_match() returns a partial match, it is possible to call
it again, with additional subject characters, and have it continue with
the same match. The PCRE2_DFA_RESTART option requests this action; when
- it is set, the workspace and wscount options must reference the same
- vector as before because data about the match so far is left in them
+ it is set, the workspace and wscount options must reference the same
+ vector as before because data about the match so far is left in them
after a partial match. There is more discussion of this facility in the
pcre2partial documentation.
@@ -3426,8 +3447,8 @@
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
<.*>
@@ -3442,73 +3463,73 @@
<something> <something else>
<something>
- On success, the yield of the function is a number greater than zero,
- which is the number of matched substrings. The offsets of the sub-
- strings are returned in the ovector, and can be extracted by number in
- the same way as for pcre2_match(), but the numbers bear no relation to
- any capturing groups that may exist in the pattern, because DFA match-
+ On success, the yield of the function is a number greater than zero,
+ which is the number of matched substrings. The offsets of the sub-
+ strings are returned in the ovector, and can be extracted by number in
+ the same way as for pcre2_match(), but the numbers bear no relation to
+ any capturing groups that may exist in the pattern, because DFA match-
ing does not support group capture.
- Calls to the convenience functions that extract substrings by name
- return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used
+ Calls to the convenience functions that extract substrings by name
+ return the error PCRE2_ERROR_DFA_UFUNC (unsupported function) if used
after a DFA match. The convenience functions that extract substrings by
number never return PCRE2_ERROR_NOSUBSTRING.
- The matched strings are stored in the ovector in reverse order of
- length; that is, the longest matching string is first. If there were
- too many matches to fit into the ovector, the yield of the function is
+ The matched strings are stored in the ovector in reverse order of
+ length; that is, the longest matching string is first. If there were
+ too many matches to fit into the ovector, the yield of the function is
zero, and the vector is filled with the longest matches.
- NOTE: PCRE2's "auto-possessification" optimization usually applies to
- character repeats at the end of a pattern (as well as internally). For
- example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
- matching, this means that only one possible match is found. If you
- really do want multiple matches in such cases, either use an ungreedy
- repeat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when
+ NOTE: PCRE2's "auto-possessification" optimization usually applies to
+ character repeats at the end of a pattern (as well as internally). For
+ example, the pattern "a\d+" is compiled as if it were "a\d++". For DFA
+ matching, this means that only one possible match is found. If you
+ really do want multiple matches in such cases, either use an ungreedy
+ repeat such as "a\d+?" or set the PCRE2_NO_AUTO_POSSESS option when
compiling.
Error returns from pcre2_dfa_match()
The pcre2_dfa_match() function returns a negative number when it fails.
- Many of the errors are the same as for pcre2_match(), as described
+ Many of the errors are the same as for pcre2_match(), as described
above. There are in addition the following errors that are specific to
pcre2_dfa_match():
PCRE2_ERROR_DFA_UITEM
- This return is given if pcre2_dfa_match() encounters an item in the
- pattern that it does not support, for instance, the use of \C in a UTF
+ This return is given if pcre2_dfa_match() encounters an item in the
+ pattern that it does not support, for instance, the use of \C in a UTF
mode or a backreference.
PCRE2_ERROR_DFA_UCOND
- This return is given if pcre2_dfa_match() encounters a condition item
+ This return is given if pcre2_dfa_match() encounters a condition item
that uses a backreference for the condition, or a test for recursion in
a specific group. These are not supported.
PCRE2_ERROR_DFA_WSSIZE
- This return is given if pcre2_dfa_match() runs out of space in the
+ This return is given if pcre2_dfa_match() runs out of space in the
workspace vector.
PCRE2_ERROR_DFA_RECURSE
- When a recursive subpattern is processed, the matching function calls
+ When a recursive subpattern is processed, the matching function calls
itself recursively, using private memory for the ovector and workspace.
- This error is given if the internal ovector is not large enough. This
+ This error is given if the internal ovector is not large enough. This
should be extremely rare, as a vector of size 1000 is used.
PCRE2_ERROR_DFA_BADRESTART
- When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
- some plausibility checks are made on the contents of the workspace,
- which should contain data about the previous partial match. If any of
+ When pcre2_dfa_match() is called with the PCRE2_DFA_RESTART option,
+ some plausibility checks are made on the contents of the workspace,
+ which should contain data about the previous partial match. If any of
these checks fail, this error is given.
SEE ALSO
- pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
+ pcre2build(3), pcre2callout(3), pcre2demo(3), pcre2matching(3),
pcre2partial(3), pcre2posix(3), pcre2sample(3), pcre2unicode(3).
@@ -3521,7 +3542,7 @@
REVISION
- Last updated: 27 July 2018
+ Last updated: 03 August 2018
Copyright (c) 1997-2018 University of Cambridge.
------------------------------------------------------------------------------
@@ -7192,9 +7213,10 @@
The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL,
PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options
- (which are Perl-compatible) can be changed from within the pattern by a
- sequence of Perl option letters enclosed between "(?" and ")". The
- option letters are
+ can be changed from within the pattern by a sequence of letters
+ enclosed between "(?" and ")". These options are Perl-compatible, and
+ are described in detail in the pcre2api documentation. The option let-
+ ters are:
i for PCRE2_CASELESS
m for PCRE2_MULTILINE
@@ -7204,36 +7226,36 @@
xx for PCRE2_EXTENDED_MORE
For example, (?im) sets caseless, multiline matching. It is also possi-
- ble to unset these options by preceding the relevant letters with a
+ ble to unset these options by preceding the relevant letters with a
hyphen, for example (?-im). The two "extended" options are not indepen-
dent; unsetting either one cancels the effects of both of them.
- A combined setting and unsetting such as (?im-sx), which sets
- PCRE2_CASELESS and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and
- PCRE2_EXTENDED, is also permitted. Only one hyphen may appear in the
- options string. If a letter appears both before and after the hyphen,
- the option is unset. An empty options setting "(?)" is allowed. Need-
+ A combined setting and unsetting such as (?im-sx), which sets
+ PCRE2_CASELESS and PCRE2_MULTILINE while unsetting PCRE2_DOTALL and
+ PCRE2_EXTENDED, is also permitted. Only one hyphen may appear in the
+ options string. If a letter appears both before and after the hyphen,
+ the option is unset. An empty options setting "(?)" is allowed. Need-
less to say, it has no effect.
- If the first character following (? is a circumflex, it causes all of
- the above options to be unset. Thus, (?^) is equivalent to (?-imnsx).
- Letters may follow the circumflex to cause some options to be re-
+ If the first character following (? is a circumflex, it causes all of
+ the above options to be unset. Thus, (?^) is equivalent to (?-imnsx).
+ Letters may follow the circumflex to cause some options to be re-
instated, but a hyphen may not appear.
- The PCRE2-specific options PCRE2_DUPNAMES and PCRE2_UNGREEDY can be
- changed in the same way as the Perl-compatible options by using the
+ The PCRE2-specific options PCRE2_DUPNAMES and PCRE2_UNGREEDY can be
+ changed in the same way as the Perl-compatible options by using the
characters J and U respectively. However, these are not unset by (?^).
- When one of these option changes occurs at top level (that is, not
- inside subpattern parentheses), the change applies to the remainder of
- the pattern that follows. An option change within a subpattern (see
- below for a description of subpatterns) affects only that part of the
+ When one of these option changes occurs at top level (that is, not
+ inside subpattern parentheses), the change applies to the remainder of
+ the pattern that follows. An option change within a subpattern (see
+ below for a description of subpatterns) affects only that part of the
subpattern that follows it, so
(a(?i)b)c
- matches abc and aBc and no other strings (assuming PCRE2_CASELESS is
- not used). By this means, options can be made to have different set-
+ matches abc and aBc and no other strings (assuming PCRE2_CASELESS is
+ not used). By this means, options can be made to have different set-
tings in different parts of the pattern. Any changes made in one alter-
native do carry on into subsequent branches within the same subpattern.
For example,
@@ -7240,13 +7262,13 @@
(a(?i)b|c)
- matches "ab", "aB", "c", and "C", even though when matching "C" the
- first branch is abandoned before the option setting. This is because
- the effects of option settings happen at compile time. There would be
+ matches "ab", "aB", "c", and "C", even though when matching "C" the
+ first branch is abandoned before the option setting. This is because
+ the effects of option settings happen at compile time. There would be
some very weird behaviour otherwise.
- As a convenient shorthand, if any option settings are required at the
- start of a non-capturing subpattern (see the next section), the option
+ As a convenient shorthand, if any option settings are required at the
+ start of a non-capturing subpattern (see the next section), the option
letters may appear between the "?" and the ":". Thus the two patterns
(?i:saturday|sunday)
@@ -7254,14 +7276,14 @@
match exactly the same set of strings.
- Note: There are other PCRE2-specific options that can be set by the
+ Note: There are other PCRE2-specific options that can be set by the
application when the compiling function is called. The pattern can con-
- tain special leading sequences such as (*CRLF) to override what the
- application has set or what has been defaulted. Details are given in
- the section entitled "Newline sequences" above. There are also the
- (*UTF) and (*UCP) leading sequences that can be used to set UTF and
- Unicode property modes; they are equivalent to setting the PCRE2_UTF
- and PCRE2_UCP options, respectively. However, the application can set
+ tain special leading sequences such as (*CRLF) to override what the
+ application has set or what has been defaulted. Details are given in
+ the section entitled "Newline sequences" above. There are also the
+ (*UTF) and (*UCP) leading sequences that can be used to set UTF and
+ Unicode property modes; they are equivalent to setting the PCRE2_UTF
+ and PCRE2_UCP options, respectively. However, the application can set
the PCRE2_NEVER_UTF and PCRE2_NEVER_UCP options, which lock out the use
of the (*UTF) and (*UCP) sequences.
@@ -7275,18 +7297,18 @@
cat(aract|erpillar|)
- matches "cataract", "caterpillar", or "cat". Without the parentheses,
+ matches "cataract", "caterpillar", or "cat". Without the parentheses,
it would match "cataract", "erpillar" or an empty string.
- 2. It sets up the subpattern as a capturing subpattern. This means
+ 2. It sets up the subpattern as a capturing subpattern. This means
that, when the whole pattern matches, the portion of the subject string
- that matched the subpattern is passed back to the caller, separately
- from the portion that matched the whole pattern. (This applies only to
- the traditional matching function; the DFA matching function does not
+ that matched the subpattern is passed back to the caller, separately
+ from the portion that matched the whole pattern. (This applies only to
+ the traditional matching function; the DFA matching function does not
support capturing.)
Opening parentheses are counted from left to right (starting from 1) to
- obtain numbers for the capturing subpatterns. For example, if the
+ obtain numbers for the capturing subpatterns. For example, if the
string "the red king" is matched against the pattern
the ((red|white) (king|queen))
@@ -7294,12 +7316,12 @@
the captured substrings are "red king", "red", and "king", and are num-
bered 1, 2, and 3, respectively.
- The fact that plain parentheses fulfil two functions is not always
- helpful. There are often times when a grouping subpattern is required
- without a capturing requirement. If an opening parenthesis is followed
- by a question mark and a colon, the subpattern does not do any captur-
- ing, and is not counted when computing the number of any subsequent
- capturing subpatterns. For example, if the string "the white queen" is
+ The fact that plain parentheses fulfil two functions is not always
+ helpful. There are often times when a grouping subpattern is required
+ without a capturing requirement. If an opening parenthesis is followed
+ by a question mark and a colon, the subpattern does not do any captur-
+ ing, and is not counted when computing the number of any subsequent
+ capturing subpatterns. For example, if the string "the white queen" is
matched against the pattern
the ((?:red|white) (king|queen))
@@ -7307,8 +7329,8 @@
the captured substrings are "white queen" and "queen", and are numbered
1 and 2. The maximum number of capturing subpatterns is 65535.
- As a convenient shorthand, if any option settings are required at the
- start of a non-capturing subpattern, the option letters may appear
+ As a convenient shorthand, if any option settings are required at the
+ start of a non-capturing subpattern, the option letters may appear
between the "?" and the ":". Thus the two patterns
(?i:saturday|sunday)
@@ -7315,9 +7337,9 @@
(?:(?i)saturday|sunday)
match exactly the same set of strings. Because alternative branches are
- tried from left to right, and options are not reset until the end of
- the subpattern is reached, an option setting in one branch does affect
- subsequent branches, so the above patterns match "SUNDAY" as well as
+ tried from left to right, and options are not reset until the end of
+ the subpattern is reached, an option setting in one branch does affect
+ subsequent branches, so the above patterns match "SUNDAY" as well as
"Saturday".
@@ -7324,20 +7346,20 @@
DUPLICATE SUBPATTERN NUMBERS
Perl 5.10 introduced a feature whereby each alternative in a subpattern
- uses the same numbers for its capturing parentheses. Such a subpattern
- starts with (?| and is itself a non-capturing subpattern. For example,
+ uses the same numbers for its capturing parentheses. Such a subpattern
+ starts with (?| and is itself a non-capturing subpattern. For example,
consider this pattern:
(?|(Sat)ur|(Sun))day
- Because the two alternatives are inside a (?| group, both sets of cap-
- turing parentheses are numbered one. Thus, when the pattern matches,
- you can look at captured substring number one, whichever alternative
- matched. This construct is useful when you want to capture part, but
+ Because the two alternatives are inside a (?| group, both sets of cap-
+ turing parentheses are numbered one. Thus, when the pattern matches,
+ you can look at captured substring number one, whichever alternative
+ matched. This construct is useful when you want to capture part, but
not all, of one of a number of alternatives. Inside a (?| group, paren-
- theses are numbered as usual, but the number is reset at the start of
- each branch. The numbers of any capturing parentheses that follow the
- subpattern start after the highest number used in any branch. The fol-
+ theses are numbered as usual, but the number is reset at the start of
+ each branch. The numbers of any capturing parentheses that follow the
+ subpattern start after the highest number used in any branch. The fol-
lowing example is taken from the Perl documentation. The numbers under-
neath show in which buffer the captured content will be stored.
@@ -7345,14 +7367,14 @@
/ ( a ) (?| x ( y ) z | (p (q) r) | (t) u (v) ) ( z ) /x
# 1 2 2 3 2 3 4
- A backreference to a numbered subpattern uses the most recent value
- that is set for that number by any subpattern. The following pattern
+ A backreference to a numbered subpattern uses the most recent value
+ that is set for that number by any subpattern. The following pattern
matches "abcabc" or "defdef":
/(?|(abc)|(def))\1/
- In contrast, a subroutine call to a numbered subpattern always refers
- to the first one in the pattern with the given number. The following
+ In contrast, a subroutine call to a numbered subpattern always refers
+ to the first one in the pattern with the given number. The following
pattern matches "abcabc" or "defabc":
/(?|(abc)|(def))(?1)/
@@ -7360,47 +7382,47 @@
A relative reference such as (?-1) is no different: it is just a conve-
nient way of computing an absolute group number.
- If a condition test for a subpattern's having matched refers to a non-
- unique number, the test is true if any of the subpatterns of that num-
+ If a condition test for a subpattern's having matched refers to a non-
+ unique number, the test is true if any of the subpatterns of that num-
ber have matched.
- An alternative approach to using this "branch reset" feature is to use
+ An alternative approach to using this "branch reset" feature is to use
duplicate named subpatterns, as described in the next section.
NAMED SUBPATTERNS
- Identifying capturing parentheses by number is simple, but it can be
- very hard to keep track of the numbers in complicated regular expres-
- sions. Furthermore, if an expression is modified, the numbers may
+ Identifying capturing parentheses by number is simple, but it can be
+ very hard to keep track of the numbers in complicated regular expres-
+ sions. Furthermore, if an expression is modified, the numbers may
change. To help with this difficulty, PCRE2 supports the naming of sub-
patterns. This feature was not added to Perl until release 5.10. Python
- had the feature earlier, and PCRE1 introduced it at release 4.0, using
- the Python syntax. PCRE2 supports both the Perl and the Python syntax.
- Perl allows identically numbered subpatterns to have different names,
+ had the feature earlier, and PCRE1 introduced it at release 4.0, using
+ the Python syntax. PCRE2 supports both the Perl and the Python syntax.
+ Perl allows identically numbered subpatterns to have different names,
but PCRE2 does not.
- In PCRE2, a subpattern can be named in one of three ways: (?<name>...)
- or (?'name'...) as in Perl, or (?P<name>...) as in Python. References
+ In PCRE2, a subpattern can be named in one of three ways: (?<name>...)
+ or (?'name'...) as in Perl, or (?P<name>...) as in Python. References
to capturing parentheses from other parts of the pattern, such as back-
- references, recursion, and conditions, can be made by name as well as
+ references, recursion, and conditions, can be made by name as well as
by number.
- Names consist of up to 32 alphanumeric characters and underscores, but
- must start with a non-digit. Named capturing parentheses are still
- allocated numbers as well as names, exactly as if the names were not
+ Names consist of up to 32 alphanumeric characters and underscores, but
+ must start with a non-digit. Named capturing parentheses are still
+ allocated numbers as well as names, exactly as if the names were not
present. The PCRE2 API provides function calls for extracting the name-
- to-number translation table from a compiled pattern. There are also
+ to-number translation table from a compiled pattern. There are also
convenience functions for extracting a captured substring by name.
- By default, a name must be unique within a pattern, but it is possible
- to relax this constraint by setting the PCRE2_DUPNAMES option at com-
- pile time. (Duplicate names are also always permitted for subpatterns
- with the same number, set up as described in the previous section.)
- Duplicate names can be useful for patterns where only one instance of
+ By default, a name must be unique within a pattern, but it is possible
+ to relax this constraint by setting the PCRE2_DUPNAMES option at com-
+ pile time. (Duplicate names are also always permitted for subpatterns
+ with the same number, set up as described in the previous section.)
+ Duplicate names can be useful for patterns where only one instance of
the named parentheses can match. Suppose you want to match the name of
- a weekday, either as a 3-letter abbreviation or as the full name, and
- in both cases you want to extract the abbreviation. This pattern
+ a weekday, either as a 3-letter abbreviation or as the full name, and
+ in both cases you want to extract the abbreviation. This pattern
(ignoring the line breaks) does the job:
(?<DN>Mon|Fri|Sun)(?:day)?|
@@ -7409,18 +7431,18 @@
(?<DN>Thu)(?:rsday)?|
(?<DN>Sat)(?:urday)?
- There are five capturing substrings, but only one is ever set after a
+ There are five capturing substrings, but only one is ever set after a
match. (An alternative way of solving this problem is to use a "branch
reset" subpattern, as described in the previous section.)
- The convenience functions for extracting the data by name returns the
- substring for the first (and in this example, the only) subpattern of
- that name that matched. This saves searching to find which numbered
+ The convenience functions for extracting the data by name returns the
+ substring for the first (and in this example, the only) subpattern of
+ that name that matched. This saves searching to find which numbered
subpattern it was.
If you make a backreference to a non-unique named subpattern from else-
- where in the pattern, the subpatterns to which the name refers are
- checked in the order in which they appear in the overall pattern. The
+ where in the pattern, the subpatterns to which the name refers are
+ checked in the order in which they appear in the overall pattern. The
first one that is set is used for the reference. For example, this pat-
tern matches both "foofoo" and "barbar" but not "foobar" or "barfoo":
@@ -7428,22 +7450,22 @@
If you make a subroutine call to a non-unique named subpattern, the one
- that corresponds to the first occurrence of the name is used. In the
+ that corresponds to the first occurrence of the name is used. In the
absence of duplicate numbers (see the previous section) this is the one
with the lowest number.
If you use a named reference in a condition test (see the section about
conditions below), either to check whether a subpattern has matched, or
- to check for recursion, all subpatterns with the same name are tested.
- If the condition is true for any one of them, the overall condition is
- true. This is the same behaviour as testing by number. For further
- details of the interfaces for handling named subpatterns, see the
+ to check for recursion, all subpatterns with the same name are tested.
+ If the condition is true for any one of them, the overall condition is
+ true. This is the same behaviour as testing by number. For further
+ details of the interfaces for handling named subpatterns, see the
pcre2api documentation.
Warning: You cannot use different names to distinguish between two sub-
- patterns with the same number because PCRE2 uses only the numbers when
+ patterns with the same number because PCRE2 uses only the numbers when
matching. For this reason, an error is given at compile time if differ-
- ent names are given to subpatterns with the same number. However, you
+ ent names are given to subpatterns with the same number. However, you
can always give the same name to subpatterns with the same number, even
when PCRE2_DUPNAMES is not set.
@@ -7450,7 +7472,7 @@
REPETITION
- Repetition is specified by quantifiers, which can follow any of the
+ Repetition is specified by quantifiers, which can follow any of the
following items:
a literal data character
@@ -7464,17 +7486,17 @@
a parenthesized subpattern (including most assertions)
a subroutine call to a subpattern (recursive or otherwise)
- The general repetition quantifier specifies a minimum and maximum num-
- ber of permitted matches, by giving the two numbers in curly brackets
- (braces), separated by a comma. The numbers must be less than 65536,
+ The general repetition quantifier specifies a minimum and maximum num-
+ ber of permitted matches, by giving the two numbers in curly brackets
+ (braces), separated by a comma. The numbers must be less than 65536,
and the first must be less than or equal to the second. For example:
z{2,4}
- matches "zz", "zzz", or "zzzz". A closing brace on its own is not a
- special character. If the second number is omitted, but the comma is
- present, there is no upper limit; if the second number and the comma
- are both omitted, the quantifier specifies an exact number of required
+ matches "zz", "zzz", or "zzzz". A closing brace on its own is not a
+ special character. If the second number is omitted, but the comma is
+ present, there is no upper limit; if the second number and the comma
+ are both omitted, the quantifier specifies an exact number of required
matches. Thus
[aeiou]{3,}
@@ -7483,26 +7505,26 @@
\d{8}
- matches exactly 8 digits. An opening curly bracket that appears in a
- position where a quantifier is not allowed, or one that does not match
- the syntax of a quantifier, is taken as a literal character. For exam-
+ matches exactly 8 digits. An opening curly bracket that appears in a
+ position where a quantifier is not allowed, or one that does not match
+ the syntax of a quantifier, is taken as a literal character. For exam-
ple, {,6} is not a quantifier, but a literal string of four characters.
In UTF modes, quantifiers apply to characters rather than to individual
- code units. Thus, for example, \x{100}{2} matches two characters, each
+ code units. Thus, for example, \x{100}{2} matches two characters, each
of which is represented by a two-byte sequence in a UTF-8 string. Simi-
- larly, \X{3} matches three Unicode extended grapheme clusters, each of
- which may be several code units long (and they may be of different
+ larly, \X{3} matches three Unicode extended grapheme clusters, each of
+ which may be several code units long (and they may be of different
lengths).
The quantifier {0} is permitted, causing the expression to behave as if
the previous item and the quantifier were not present. This may be use-
- ful for subpatterns that are referenced as subroutines from elsewhere
+ ful for subpatterns that are referenced as subroutines from elsewhere
in the pattern (but see also the section entitled "Defining subpatterns
- for use by reference only" below). Items other than subpatterns that
+ for use by reference only" below). Items other than subpatterns that
have a {0} quantifier are omitted from the compiled pattern.
- For convenience, the three most common quantifiers have single-charac-
+ For convenience, the three most common quantifiers have single-charac-
ter abbreviations:
* is equivalent to {0,}
@@ -7509,24 +7531,24 @@
+ is equivalent to {1,}
? is equivalent to {0,1}
- It is possible to construct infinite loops by following a subpattern
+ It is possible to construct infinite loops by following a subpattern
that can match no characters with a quantifier that has no upper limit,
for example:
(a?)*
- Earlier versions of Perl and PCRE1 used to give an error at compile
+ Earlier versions of Perl and PCRE1 used to give an error at compile
time for such patterns. However, because there are cases where this can
be useful, such patterns are now accepted, but if any repetition of the
- subpattern does in fact match no characters, the loop is forcibly bro-
+ subpattern does in fact match no characters, the loop is forcibly bro-
ken.
- By default, the quantifiers are "greedy", that is, they match as much
- as possible (up to the maximum number of permitted times), without
- causing the rest of the pattern to fail. The classic example of where
+ By default, the quantifiers are "greedy", that is, they match as much
+ as possible (up to the maximum number of permitted times), without
+ causing the rest of the pattern to fail. The classic example of where
this gives problems is in trying to match comments in C programs. These
- appear between /* and */ and within the comment, individual * and /
- characters may appear. An attempt to match C comments by applying the
+ appear between /* and */ and within the comment, individual * and /
+ characters may appear. An attempt to match C comments by applying the
pattern
/\*.*\*/
@@ -7535,19 +7557,19 @@
/* first comment */ not comment /* second comment */
- fails, because it matches the entire string owing to the greediness of
+ fails, because it matches the entire string owing to the greediness of
the .* item.
If a quantifier is followed by a question mark, it ceases to be greedy,
- and instead matches the minimum number of times possible, so the pat-
+ and instead matches the minimum number of times possible, so the pat-
tern
/\*.*?\*/
- does the right thing with the C comments. The meaning of the various
- quantifiers is not otherwise changed, just the preferred number of
- matches. Do not confuse this use of question mark with its use as a
- quantifier in its own right. Because it has two uses, it can sometimes
+ does the right thing with the C comments. The meaning of the various
+ quantifiers is not otherwise changed, just the preferred number of
+ matches. Do not confuse this use of question mark with its use as a
+ quantifier in its own right. Because it has two uses, it can sometimes
appear doubled, as in
\d??\d
@@ -7556,45 +7578,45 @@
only way the rest of the pattern matches.
If the PCRE2_UNGREEDY option is set (an option that is not available in
- Perl), the quantifiers are not greedy by default, but individual ones
- can be made greedy by following them with a question mark. In other
+ Perl), the quantifiers are not greedy by default, but individual ones
+ can be made greedy by following them with a question mark. In other
words, it inverts the default behaviour.
- When a parenthesized subpattern is quantified with a minimum repeat
- count that is greater than 1 or with a limited maximum, more memory is
- required for the compiled pattern, in proportion to the size of the
+ When a parenthesized subpattern is quantified with a minimum repeat
+ count that is greater than 1 or with a limited maximum, more memory is
+ required for the compiled pattern, in proportion to the size of the
minimum or maximum.
- If a pattern starts with .* or .{0,} and the PCRE2_DOTALL option
- (equivalent to Perl's /s) is set, thus allowing the dot to match new-
- lines, the pattern is implicitly anchored, because whatever follows
- will be tried against every character position in the subject string,
- so there is no point in retrying the overall match at any position
+ If a pattern starts with .* or .{0,} and the PCRE2_DOTALL option
+ (equivalent to Perl's /s) is set, thus allowing the dot to match new-
+ lines, the pattern is implicitly anchored, because whatever follows
+ will be tried against every character position in the subject string,
+ so there is no point in retrying the overall match at any position
after the first. PCRE2 normally treats such a pattern as though it were
preceded by \A.
- In cases where it is known that the subject string contains no new-
- lines, it is worth setting PCRE2_DOTALL in order to obtain this opti-
+ In cases where it is known that the subject string contains no new-
+ lines, it is worth setting PCRE2_DOTALL in order to obtain this opti-
mization, or alternatively, using ^ to indicate anchoring explicitly.
- However, there are some cases where the optimization cannot be used.
- When .* is inside capturing parentheses that are the subject of a
- backreference elsewhere in the pattern, a match at the start may fail
+ However, there are some cases where the optimization cannot be used.
+ When .* is inside capturing parentheses that are the subject of a
+ backreference elsewhere in the pattern, a match at the start may fail
where a later one succeeds. Consider, for example:
(.*)abc\1
- If the subject is "xyz123abc123" the match point is the fourth charac-
+ If the subject is "xyz123abc123" the match point is the fourth charac-
ter. For this reason, such a pattern is not implicitly anchored.
- Another case where implicit anchoring is not applied is when the lead-
- ing .* is inside an atomic group. Once again, a match at the start may
+ Another case where implicit anchoring is not applied is when the lead-
+ ing .* is inside an atomic group. Once again, a match at the start may
fail where a later one succeeds. Consider this pattern:
(?>.*?a)b
- It matches "ab" in the subject "aab". The use of the backtracking con-
- trol verbs (*PRUNE) and (*SKIP) also disable this optimization, and
+ It matches "ab" in the subject "aab". The use of the backtracking con-
+ trol verbs (*PRUNE) and (*SKIP) also disable this optimization, and
there is an option, PCRE2_NO_DOTSTAR_ANCHOR, to do so explicitly.
When a capturing subpattern is repeated, the value captured is the sub-
@@ -7603,8 +7625,8 @@
(tweedle[dume]{3}\s*)+
has matched "tweedledum tweedledee" the value of the captured substring
- is "tweedledee". However, if there are nested capturing subpatterns,
- the corresponding captured values may have been set in previous itera-
+ is "tweedledee". However, if there are nested capturing subpatterns,
+ the corresponding captured values may have been set in previous itera-
tions. For example, after
(a|(b))+
@@ -7614,53 +7636,53 @@
ATOMIC GROUPING AND POSSESSIVE QUANTIFIERS
- With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
- repetition, failure of what follows normally causes the repeated item
- to be re-evaluated to see if a different number of repeats allows the
- rest of the pattern to match. Sometimes it is useful to prevent this,
- either to change the nature of the match, or to cause it fail earlier
- than it otherwise might, when the author of the pattern knows there is
+ With both maximizing ("greedy") and minimizing ("ungreedy" or "lazy")
+ repetition, failure of what follows normally causes the repeated item
+ to be re-evaluated to see if a different number of repeats allows the
+ rest of the pattern to match. Sometimes it is useful to prevent this,
+ either to change the nature of the match, or to cause it fail earlier
+ than it otherwise might, when the author of the pattern knows there is
no point in carrying on.
- Consider, for example, the pattern \d+foo when applied to the subject
+ Consider, for example, the pattern \d+foo when applied to the subject
line
123456bar
After matching all 6 digits and then failing to match "foo", the normal
- action of the matcher is to try again with only 5 digits matching the
- \d+ item, and then with 4, and so on, before ultimately failing.
- "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides
- the means for specifying that once a subpattern has matched, it is not
+ action of the matcher is to try again with only 5 digits matching the
+ \d+ item, and then with 4, and so on, before ultimately failing.
+ "Atomic grouping" (a term taken from Jeffrey Friedl's book) provides
+ the means for specifying that once a subpattern has matched, it is not
to be re-evaluated in this way.
- If we use atomic grouping for the previous example, the matcher gives
- up immediately on failing to match "foo" the first time. The notation
+ If we use atomic grouping for the previous example, the matcher gives
+ up immediately on failing to match "foo" the first time. The notation
is a kind of special parenthesis, starting with (?> as in this example:
(?>\d+)foo
- This kind of parenthesis "locks up" the part of the pattern it con-
- tains once it has matched, and a failure further into the pattern is
- prevented from backtracking into it. Backtracking past it to previous
+ This kind of parenthesis "locks up" the part of the pattern it con-
+ tains once it has matched, and a failure further into the pattern is
+ prevented from backtracking into it. Backtracking past it to previous
items, however, works as normal.
- An alternative description is that a subpattern of this type matches
- exactly the string of characters that an identical standalone pattern
+ An alternative description is that a subpattern of this type matches
+ exactly the string of characters that an identical standalone pattern
would match, if anchored at the current point in the subject string.
Atomic grouping subpatterns are not capturing subpatterns. Simple cases
such as the above example can be thought of as a maximizing repeat that
- must swallow everything it can. So, while both \d+ and \d+? are pre-
- pared to adjust the number of digits they match in order to make the
+ must swallow everything it can. So, while both \d+ and \d+? are pre-
+ pared to adjust the number of digits they match in order to make the
rest of the pattern match, (?>\d+) can only match an entire sequence of
digits.
- Atomic groups in general can of course contain arbitrarily complicated
- subpatterns, and can be nested. However, when the subpattern for an
+ Atomic groups in general can of course contain arbitrarily complicated
+ subpatterns, and can be nested. However, when the subpattern for an
atomic group is just a single repeated item, as in the example above, a
- simpler notation, called a "possessive quantifier" can be used. This
- consists of an additional + character following a quantifier. Using
+ simpler notation, called a "possessive quantifier" can be used. This
+ consists of an additional + character following a quantifier. Using
this notation, the previous example can be rewritten as
\d++foo
@@ -7670,46 +7692,46 @@
(abc|xyz){2,3}+
- Possessive quantifiers are always greedy; the setting of the
- PCRE2_UNGREEDY option is ignored. They are a convenient notation for
- the simpler forms of atomic group. However, there is no difference in
+ Possessive quantifiers are always greedy; the setting of the
+ PCRE2_UNGREEDY option is ignored. They are a convenient notation for
+ the simpler forms of atomic group. However, there is no difference in
the meaning of a possessive quantifier and the equivalent atomic group,
- though there may be a performance difference; possessive quantifiers
+ though there may be a performance difference; possessive quantifiers
should be slightly faster.
- The possessive quantifier syntax is an extension to the Perl 5.8 syn-
- tax. Jeffrey Friedl originated the idea (and the name) in the first
+ The possessive quantifier syntax is an extension to the Perl 5.8 syn-
+ tax. Jeffrey Friedl originated the idea (and the name) in the first
edition of his book. Mike McCloskey liked it, so implemented it when he
built Sun's Java package, and PCRE1 copied it from there. It ultimately
found its way into Perl at release 5.10.
- PCRE2 has an optimization that automatically "possessifies" certain
- simple pattern constructs. For example, the sequence A+B is treated as
- A++B because there is no point in backtracking into a sequence of A's
+ PCRE2 has an optimization that automatically "possessifies" certain
+ simple pattern constructs. For example, the sequence A+B is treated as
+ A++B because there is no point in backtracking into a sequence of A's
when B must follow. This feature can be disabled by the PCRE2_NO_AUTO-
POSSESS option, or starting the pattern with (*NO_AUTO_POSSESS).
- When a pattern contains an unlimited repeat inside a subpattern that
- can itself be repeated an unlimited number of times, the use of an
- atomic group is the only way to avoid some failing matches taking a
+ When a pattern contains an unlimited repeat inside a subpattern that
+ can itself be repeated an unlimited number of times, the use of an
+ atomic group is the only way to avoid some failing matches taking a
very long time indeed. The pattern
(\D+|<\d+>)*[!?]
- matches an unlimited number of substrings that either consist of non-
- digits, or digits enclosed in <>, followed by either ! or ?. When it
+ matches an unlimited number of substrings that either consist of non-
+ digits, or digits enclosed in <>, followed by either ! or ?. When it
matches, it runs quickly. However, if it is applied to
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
- it takes a long time before reporting failure. This is because the
- string can be divided between the internal \D+ repeat and the external
- * repeat in a large number of ways, and all have to be tried. (The
- example uses [!?] rather than a single character at the end, because
- both PCRE2 and Perl have an optimization that allows for fast failure
- when a single character is used. They remember the last single charac-
- ter that is required for a match, and fail early if it is not present
- in the string.) If the pattern is changed so that it uses an atomic
+ it takes a long time before reporting failure. This is because the
+ string can be divided between the internal \D+ repeat and the external
+ * repeat in a large number of ways, and all have to be tried. (The
+ example uses [!?] rather than a single character at the end, because
+ both PCRE2 and Perl have an optimization that allows for fast failure
+ when a single character is used. They remember the last single charac-
+ ter that is required for a match, and fail early if it is not present
+ in the string.) If the pattern is changed so that it uses an atomic
group, like this:
((?>\D+)|<\d+>)*[!?]
@@ -7720,29 +7742,29 @@
BACKREFERENCES
Outside a character class, a backslash followed by a digit greater than
- 0 (and possibly further digits) is a backreference to a capturing sub-
- pattern earlier (that is, to its left) in the pattern, provided there
+ 0 (and possibly further digits) is a backreference to a capturing sub-
+ pattern earlier (that is, to its left) in the pattern, provided there
have been that many previous capturing left parentheses.
- However, if the decimal number following the backslash is less than 8,
- it is always taken as a backreference, and causes an error only if
- there are not that many capturing left parentheses in the entire pat-
- tern. In other words, the parentheses that are referenced need not be
- to the left of the reference for numbers less than 8. A "forward back-
- reference" of this type can make sense when a repetition is involved
- and the subpattern to the right has participated in an earlier itera-
+ However, if the decimal number following the backslash is less than 8,
+ it is always taken as a backreference, and causes an error only if
+ there are not that many capturing left parentheses in the entire pat-
+ tern. In other words, the parentheses that are referenced need not be
+ to the left of the reference for numbers less than 8. A "forward back-
+ reference" of this type can make sense when a repetition is involved
+ and the subpattern to the right has participated in an earlier itera-
tion.
- It is not possible to have a numerical "forward backreference" to a
- subpattern whose number is 8 or more using this syntax because a
- sequence such as \50 is interpreted as a character defined in octal.
+ It is not possible to have a numerical "forward backreference" to a
+ subpattern whose number is 8 or more using this syntax because a
+ sequence such as \50 is interpreted as a character defined in octal.
See the subsection entitled "Non-printing characters" above for further
- details of the handling of digits following a backslash. There is no
- such problem when named parentheses are used. A backreference to any
+ details of the handling of digits following a backslash. There is no
+ such problem when named parentheses are used. A backreference to any
subpattern is possible using named parentheses (see below).
- Another way of avoiding the ambiguity inherent in the use of digits
- following a backslash is to use the \g escape sequence. This escape
+ Another way of avoiding the ambiguity inherent in the use of digits
+ following a backslash is to use the \g escape sequence. This escape
must be followed by a signed or unsigned number, optionally enclosed in
braces. These examples are all identical:
@@ -7750,9 +7772,9 @@
(ring), \g1
(ring), \g{1}
- An unsigned number specifies an absolute reference without the ambigu-
+ An unsigned number specifies an absolute reference without the ambigu-
ity that is present in the older syntax. It is also useful when literal
- digits follow the reference. A signed number is a relative reference.
+ digits follow the reference. A signed number is a relative reference.
Consider this example:
(abc(def)ghi)\g{-1}
@@ -7759,37 +7781,37 @@
The sequence \g{-1} is a reference to the most recently started captur-
ing subpattern before \g, that is, is it equivalent to \2 in this exam-
- ple. Similarly, \g{-2} would be equivalent to \1. The use of relative
- references can be helpful in long patterns, and also in patterns that
- are created by joining together fragments that contain references
+ ple. Similarly, \g{-2} would be equivalent to \1. The use of relative
+ references can be helpful in long patterns, and also in patterns that
+ are created by joining together fragments that contain references
within themselves.
- The sequence \g{+1} is a reference to the next capturing subpattern.
- This kind of forward reference can be useful it patterns that repeat.
+ The sequence \g{+1} is a reference to the next capturing subpattern.
+ This kind of forward reference can be useful it patterns that repeat.
Perl does not support the use of + in this way.
A backreference matches whatever actually matched the capturing subpat-
- tern in the current subject string, rather than anything matching the
- subpattern itself (see "Subpatterns as subroutines" below for a way of
+ tern in the current subject string, rather than anything matching the
+ subpattern itself (see "Subpatterns as subroutines" below for a way of
doing that). So the pattern
(sens|respons)e and \1ibility
- matches "sense and sensibility" and "response and responsibility", but
- not "sense and responsibility". If caseful matching is in force at the
- time of the backreference, the case of letters is relevant. For exam-
+ matches "sense and sensibility" and "response and responsibility", but
+ not "sense and responsibility". If caseful matching is in force at the
+ time of the backreference, the case of letters is relevant. For exam-
ple,
((?i)rah)\s+\1
- matches "rah rah" and "RAH RAH", but not "RAH rah", even though the
+ matches "rah rah" and "RAH RAH", but not "RAH rah", even though the
original capturing subpattern is matched caselessly.
- There are several different ways of writing backreferences to named
- subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or
- \k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's
- unified backreference syntax, in which \g can be used for both numeric
- and named references, is also supported. We could rewrite the above
+ There are several different ways of writing backreferences to named
+ subpatterns. The .NET syntax \k{name} and the Perl syntax \k<name> or
+ \k'name' are supported, as is the Python syntax (?P=name). Perl 5.10's
+ unified backreference syntax, in which \g can be used for both numeric
+ and named references, is also supported. We could rewrite the above
example in any of the following ways:
(?<p1>(?i)rah)\s+\k<p1>
@@ -7797,25 +7819,26 @@
(?P<p1>(?i)rah)\s+(?P=p1)
(?<p1>(?i)rah)\s+\g{p1}
- A subpattern that is referenced by name may appear in the pattern
+ A subpattern that is referenced by name may appear in the pattern
before or after the reference.
- There may be more than one backreference to the same subpattern. If a
- subpattern has not actually been used in a particular match, any back-
+ There may be more than one backreference to the same subpattern. If a
+ subpattern has not actually been used in a particular match, any back-
references to it always fail by default. For example, the pattern
(a|(bc))\2
- always fails if it starts to match "a" rather than "bc". However, if
+ always fails if it starts to match "a" rather than "bc". However, if
the PCRE2_MATCH_UNSET_BACKREF option is set at compile time, a backref-
erence to an unset value matches an empty string.
- Because there may be many capturing parentheses in a pattern, all dig-
- its following a backslash are taken as part of a potential backrefer-
- ence number. If the pattern continues with a digit character, some
- delimiter must be used to terminate the backreference. If the
- PCRE2_EXTENDED option is set, this can be white space. Otherwise, the
- \g{ syntax or an empty comment (see "Comments" below) can be used.
+ Because there may be many capturing parentheses in a pattern, all dig-
+ its following a backslash are taken as part of a potential backrefer-
+ ence number. If the pattern continues with a digit character, some
+ delimiter must be used to terminate the backreference. If the
+ PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is set, this can be white
+ space. Otherwise, the \g{ syntax or an empty comment (see "Comments"
+ below) can be used.
Recursive backreferences
@@ -8245,17 +8268,17 @@
The sequence (?# marks the start of a comment that continues up to the
next closing parenthesis. Nested parentheses are not permitted. If the
- PCRE2_EXTENDED option is set, an unescaped # character also introduces
- a comment, which in this case continues to immediately after the next
- newline character or character sequence in the pattern. Which charac-
- ters are interpreted as newlines is controlled by an option passed to
- the compiling function or by a special sequence at the start of the
- pattern, as described in the section entitled "Newline conventions"
- above. Note that the end of this type of comment is a literal newline
- sequence in the pattern; escape sequences that happen to represent a
- newline do not count. For example, consider this pattern when
- PCRE2_EXTENDED is set, and the default newline convention (a single
- linefeed character) is in force:
+ PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is set, an unescaped #
+ character also introduces a comment, which in this case continues to
+ immediately after the next newline character or character sequence in
+ the pattern. Which characters are interpreted as newlines is controlled
+ by an option passed to the compiling function or by a special sequence
+ at the start of the pattern, as described in the section entitled "New-
+ line conventions" above. Note that the end of this type of comment is a
+ literal newline sequence in the pattern; escape sequences that happen
+ to represent a newline do not count. For example, consider this pattern
+ when PCRE2_EXTENDED is set, and the default newline convention (a sin-
+ gle linefeed character) is in force:
abc #comment \n still comment
@@ -8602,10 +8625,10 @@
A closing parenthesis can be included in a name either as \) or between
\Q and \E. In addition to backslash processing, if the PCRE2_EXTENDED
- option is also set, unescaped whitespace in verb names is skipped, and
- #-comments are recognized, exactly as in the rest of the pattern.
- PCRE2_EXTENDED does not affect verb names unless PCRE2_ALT_VERBNAMES is
- also set.
+ or PCRE2_EXTENDED_MORE option is also set, unescaped whitespace in verb
+ names is skipped, and #-comments are recognized, exactly as in the rest
+ of the pattern. PCRE2_EXTENDED and PCRE2_EXTENDED_MORE do not affect
+ verb names unless PCRE2_ALT_VERBNAMES is also set.
The maximum length of a name is 255 in the 8-bit library and 65535 in
the 16-bit and 32-bit libraries. If the name is empty, that is, if the
@@ -9049,7 +9072,7 @@
REVISION
- Last updated: 28 July 2018
+ Last updated: 03 August 2018
Copyright (c) 1997-2018 University of Cambridge.
------------------------------------------------------------------------------
@@ -10151,6 +10174,8 @@
OPTION SETTING
+ Changes of these options within a group are automatically cancelled at
+ the end of the group.
(?i) caseless
(?J) allow duplicate names
@@ -10163,14 +10188,14 @@
(?-...) unset option(s)
(?^) unset imnsx options
- Unsetting x or xx unsets both. Several options may be set at once, and
+ Unsetting x or xx unsets both. Several options may be set at once, and
a mixture of setting and unsetting such as (?i-x) is allowed, but there
may be only one hyphen. Setting (but no unsetting) is allowed after (?^
for example (?^in). An option setting may appear at the start of a non-
capturing group, for example (?i:...).
- The following are recognized only at the very start of a pattern or
- after one of the newline or \R options with similar syntax. More than
+ The following are recognized only at the very start of a pattern or
+ after one of the newline or \R options with similar syntax. More than
one of them may appear. For the first three, d is a decimal number.
(*LIMIT_DEPTH=d) set the backtracking limit to d
@@ -10185,17 +10210,17 @@
(*UTF) set appropriate UTF mode for the library in use
(*UCP) set PCRE2_UCP (use Unicode properties for \d etc)
- Note that LIMIT_DEPTH, LIMIT_HEAP, and LIMIT_MATCH can only reduce the
- value of the limits set by the caller of pcre2_match() or
- pcre2_dfa_match(), not increase them. LIMIT_RECURSION is an obsolete
+ Note that LIMIT_DEPTH, LIMIT_HEAP, and LIMIT_MATCH can only reduce the
+ value of the limits set by the caller of pcre2_match() or
+ pcre2_dfa_match(), not increase them. LIMIT_RECURSION is an obsolete
synonym for LIMIT_DEPTH. The application can lock out the use of (*UTF)
- and (*UCP) by setting the PCRE2_NEVER_UTF or PCRE2_NEVER_UCP options,
+ and (*UCP) by setting the PCRE2_NEVER_UTF or PCRE2_NEVER_UCP options,
respectively, at compile time.
NEWLINE CONVENTION
- These are recognized only at the very start of the pattern or after
+ These are recognized only at the very start of the pattern or after
option settings with a similar syntax.
(*CR) carriage return only
@@ -10208,7 +10233,7 @@
WHAT \R MATCHES
- These are recognized only at the very start of the pattern or after
+ These are recognized only at the very start of the pattern or after
option setting with a similar syntax.
(*BSR_ANYCRLF) CR, LF, or CRLF
@@ -10277,16 +10302,16 @@
(?(VERSION[>]=n.m) test PCRE2 version
(?(assert) assertion condition
- Note the ambiguity of (?(R) and (?(Rn) which might be named reference
- conditions or recursion tests. Such a condition is interpreted as a
+ Note the ambiguity of (?(R) and (?(Rn) which might be named reference
+ conditions or recursion tests. Such a condition is interpreted as a
reference condition if the relevant named group exists.
BACKTRACKING CONTROL
- All backtracking control verbs may be in the form (*VERB:NAME). For
- (*MARK) the name is mandatory, for the others it is optional. (*SKIP)
- changes its behaviour if :NAME is present. The others just set a name
+ All backtracking control verbs may be in the form (*VERB:NAME). For
+ (*MARK) the name is mandatory, for the others it is optional. (*SKIP)
+ changes its behaviour if :NAME is present. The others just set a name
for passing back to the caller, but this is not a name that (*SKIP) can
see. The following act immediately they are reached:
@@ -10294,7 +10319,7 @@
(*FAIL) force backtrack; synonym (*F)
(*MARK:NAME) set name to be passed back; synonym (*:NAME)
- The following act only when a subsequent match failure causes a back-
+ The following act only when a subsequent match failure causes a back-
track to reach them. They all force a match failure, but they differ in
what happens afterwards. Those that advance the start-of-match point do
so only if the pattern is not anchored.
@@ -10306,7 +10331,7 @@
(*MARK:NAME); if not found, the (*SKIP) is ignored
(*THEN) local failure, backtrack to next alternation
- The effect of one of these verbs in a group called as a subroutine is
+ The effect of one of these verbs in a group called as a subroutine is
confined to the subroutine call.
@@ -10317,14 +10342,14 @@
(?C"text") callout with string data
The allowed string delimiters are ` ' " ^ % # $ (which are the same for
- the start and the end), and the starting delimiter { matched with the
- ending delimiter }. To encode the ending delimiter within the string,
+ the start and the end), and the starting delimiter { matched with the
+ ending delimiter }. To encode the ending delimiter within the string,
double it.
SEE ALSO
- pcre2pattern(3), pcre2api(3), pcre2callout(3), pcre2matching(3),
+ pcre2pattern(3), pcre2api(3), pcre2callout(3), pcre2matching(3),
pcre2(3).
@@ -10337,7 +10362,7 @@
REVISION
- Last updated: 28 July 2018
+ Last updated: 01 August 2018
Copyright (c) 1997-2018 University of Cambridge.
------------------------------------------------------------------------------
Modified: code/trunk/doc/pcre2api.3
===================================================================
--- code/trunk/doc/pcre2api.3 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/doc/pcre2api.3 2018-08-03 09:38:36 UTC (rev 977)
@@ -1,4 +1,4 @@
-.TH PCRE2API 3 "27 July 2018" "PCRE2 10.32"
+.TH PCRE2API 3 "03 August 2018" "PCRE2 10.32"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.sp
@@ -775,10 +775,10 @@
page for details.
.P
When a pattern is compiled with the PCRE2_EXTENDED or PCRE2_EXTENDED_MORE
-option, the newline convention affects the recognition of white space and the
-end of internal comments starting with #. The value is saved with the compiled
-pattern for subsequent use by the JIT compiler and by the two interpreted
-matching functions, \fIpcre2_match()\fP and \fIpcre2_dfa_match()\fP.
+option, the newline convention affects the recognition of the end of internal
+comments starting with #. The value is saved with the compiled pattern for
+subsequent use by the JIT compiler and by the two interpreted matching
+functions, \fIpcre2_match()\fP and \fIpcre2_dfa_match()\fP.
.sp
.nf
.B int pcre2_set_parens_nest_limit(pcre2_compile_context *\fIccontext\fP,
@@ -1356,9 +1356,9 @@
option is set, normal backslash processing is applied to verb names and only an
unescaped closing parenthesis terminates the name. A closing parenthesis can be
included in a name either as \e) or between \eQ and \eE. If the PCRE2_EXTENDED
-or PCRE2_EXTENDED_MORE option is set, unescaped whitespace in verb names is
-skipped and #-comments are recognized in this mode, exactly as in the rest of
-the pattern.
+or PCRE2_EXTENDED_MORE option is set with PCRE2_ALT_VERBNAMES, unescaped
+whitespace in verb names is skipped and #-comments are recognized, exactly as
+in the rest of the pattern.
.sp
PCRE2_AUTO_CALLOUT
.sp
@@ -1445,15 +1445,36 @@
parenthesized subpatterns, nor within numerical quantifiers such as {1,3}.
Ignorable white space is permitted between an item and a following quantifier
and between a quantifier and a following + that indicates possessiveness.
+PCRE2_EXTENDED is equivalent to Perl's /x option, and it can be changed within
+a pattern by a (?x) option setting.
.P
-PCRE2_EXTENDED also causes characters between an unescaped # outside a
-character class and the next newline, inclusive, to be ignored, which makes it
-possible to include comments inside complicated patterns. Note that the end of
-this type of comment is a literal newline sequence in the pattern; escape
-sequences that happen to represent a newline do not count. PCRE2_EXTENDED is
-equivalent to Perl's /x option, and it can be changed within a pattern by a
-(?x) option setting.
+When PCRE2 is compiled without Unicode support, PCRE2_EXTENDED recognizes as
+white space only those characters with code points less than 256 that are
+flagged as white space in its low-character table. The table is normally
+created by
+.\" HREF
+\fBpcre2_maketables()\fP,
+.\"
+which uses the \fBisspace()\fP function to identify space characters. In most
+ASCII environments, the relevant characters are those with code points 0x0009
+(tab), 0x000A (linefeed), 0x000B (vertical tab), 0x000C (formfeed), 0x000D
+(carriage return), and 0x0020 (space).
.P
+When PCRE2 is compiled with Unicode support, in addition to these characters,
+five more Unicode "Pattern White Space" characters are recognized by
+PCRE2_EXTENDED. These are U+0085 (next line), U+200E (left-to-right mark),
+U+200F (right-to-left mark), U+2028 (line separator), and U+2029 (paragraph
+separator). This set of characters is the same as recognized by Perl's /x
+option. Note that the horizontal and vertical space characters that are matched
+by the \eh and \ev escapes in patterns are a much bigger set.
+.P
+As well as ignoring most white space, PCRE2_EXTENDED also causes characters
+between an unescaped # outside a character class and the next newline,
+inclusive, to be ignored, which makes it possible to include comments inside
+complicated patterns. Note that the end of this type of comment is a literal
+newline sequence in the pattern; escape sequences that happen to represent a
+newline do not count.
+.P
Which characters are interpreted as newlines can be specified by a setting in
the compile context that is passed to \fBpcre2_compile()\fP or by a special
sequence at the start of the pattern, as described in the section entitled
@@ -1467,9 +1488,11 @@
PCRE2_EXTENDED_MORE
.sp
This option has the effect of PCRE2_EXTENDED, but, in addition, unescaped space
-and horizontal tab characters are ignored inside a character class.
-PCRE2_EXTENDED_MORE is equivalent to Perl's 5.26 /xx option, and it can be
-changed within a pattern by a (?xx) option setting.
+and horizontal tab characters are ignored inside a character class. Note: only
+these two characters are ignored, not the full set of pattern white space
+characters that are ignored outside a character class. PCRE2_EXTENDED_MORE is
+equivalent to Perl's /xx option, and it can be changed within a pattern by a
+(?xx) option setting.
.sp
PCRE2_FIRSTLINE
.sp
@@ -3641,6 +3664,6 @@
.rs
.sp
.nf
-Last updated: 27 July 2018
+Last updated: 03 August 2018
Copyright (c) 1997-2018 University of Cambridge.
.fi
Modified: code/trunk/doc/pcre2pattern.3
===================================================================
--- code/trunk/doc/pcre2pattern.3 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/doc/pcre2pattern.3 2018-08-03 09:38:36 UTC (rev 977)
@@ -1,4 +1,4 @@
-.TH PCRE2PATTERN 3 "28 July 2018" "PCRE2 10.32"
+.TH PCRE2PATTERN 3 "03 August 2018" "PCRE2 10.32"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.SH "PCRE2 REGULAR EXPRESSION DETAILS"
@@ -1627,9 +1627,13 @@
.rs
.sp
The settings of the PCRE2_CASELESS, PCRE2_MULTILINE, PCRE2_DOTALL,
-PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options (which
-are Perl-compatible) can be changed from within the pattern by a sequence of
-Perl option letters enclosed between "(?" and ")". The option letters are
+PCRE2_EXTENDED, PCRE2_EXTENDED_MORE, and PCRE2_NO_AUTO_CAPTURE options can be
+changed from within the pattern by a sequence of letters enclosed between "(?"
+and ")". These options are Perl-compatible, and are described in detail in the
+.\" HREF
+\fBpcre2api\fP
+.\"
+documentation. The option letters are:
.sp
i for PCRE2_CASELESS
m for PCRE2_MULTILINE
@@ -2273,8 +2277,9 @@
Because there may be many capturing parentheses in a pattern, all digits
following a backslash are taken as part of a potential backreference number.
If the pattern continues with a digit character, some delimiter must be used to
-terminate the backreference. If the PCRE2_EXTENDED option is set, this can be
-white space. Otherwise, the \eg{ syntax or an empty comment (see
+terminate the backreference. If the PCRE2_EXTENDED or PCRE2_EXTENDED_MORE
+option is set, this can be white space. Otherwise, the \eg{ syntax or an empty
+comment (see
.\" HTML <a href="#comments">
.\" </a>
"Comments"
@@ -2762,12 +2767,12 @@
.P
The sequence (?# marks the start of a comment that continues up to the next
closing parenthesis. Nested parentheses are not permitted. If the
-PCRE2_EXTENDED option is set, an unescaped # character also introduces a
-comment, which in this case continues to immediately after the next newline
-character or character sequence in the pattern. Which characters are
-interpreted as newlines is controlled by an option passed to the compiling
-function or by a special sequence at the start of the pattern, as described in
-the section entitled
+PCRE2_EXTENDED or PCRE2_EXTENDED_MORE option is set, an unescaped # character
+also introduces a comment, which in this case continues to immediately after
+the next newline character or character sequence in the pattern. Which
+characters are interpreted as newlines is controlled by an option passed to the
+compiling function or by a special sequence at the start of the pattern, as
+described in the section entitled
.\" HTML <a href="#newlines">
.\" </a>
"Newline conventions"
@@ -3132,10 +3137,11 @@
are faulted.
.P
A closing parenthesis can be included in a name either as \e) or between \eQ
-and \eE. In addition to backslash processing, if the PCRE2_EXTENDED option is
-also set, unescaped whitespace in verb names is skipped, and #-comments are
-recognized, exactly as in the rest of the pattern. PCRE2_EXTENDED does not
-affect verb names unless PCRE2_ALT_VERBNAMES is also set.
+and \eE. In addition to backslash processing, if the PCRE2_EXTENDED or
+PCRE2_EXTENDED_MORE option is also set, unescaped whitespace in verb names is
+skipped, and #-comments are recognized, exactly as in the rest of the pattern.
+PCRE2_EXTENDED and PCRE2_EXTENDED_MORE do not affect verb names unless
+PCRE2_ALT_VERBNAMES is also set.
.P
The maximum length of a name is 255 in the 8-bit library and 65535 in the
16-bit and 32-bit libraries. If the name is empty, that is, if the closing
@@ -3614,6 +3620,6 @@
.rs
.sp
.nf
-Last updated: 28 July 2018
+Last updated: 03 August 2018
Copyright (c) 1997-2018 University of Cambridge.
.fi
Modified: code/trunk/doc/pcre2syntax.3
===================================================================
--- code/trunk/doc/pcre2syntax.3 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/doc/pcre2syntax.3 2018-08-03 09:38:36 UTC (rev 977)
@@ -1,4 +1,4 @@
-.TH PCRE2SYNTAX 3 "28 July 2018" "PCRE2 10.32"
+.TH PCRE2SYNTAX 3 "01 August 2018" "PCRE2 10.32"
.SH NAME
PCRE2 - Perl-compatible regular expressions (revised API)
.SH "PCRE2 REGULAR EXPRESSION SYNTAX SUMMARY"
@@ -421,6 +421,8 @@
.
.SH "OPTION SETTING"
.rs
+Changes of these options within a group are automatically cancelled at the end
+of the group.
.sp
(?i) caseless
(?J) allow duplicate names
@@ -619,6 +621,6 @@
.rs
.sp
.nf
-Last updated: 28 July 2018
+Last updated: 01 August 2018
Copyright (c) 1997-2018 University of Cambridge.
.fi
Modified: code/trunk/src/pcre2_compile.c
===================================================================
--- code/trunk/src/pcre2_compile.c 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/src/pcre2_compile.c 2018-08-03 09:38:36 UTC (rev 977)
@@ -2468,11 +2468,17 @@
/* EITHER: not both options set */
((options & (PCRE2_EXTENDED | PCRE2_ALT_VERBNAMES)) !=
(PCRE2_EXTENDED | PCRE2_ALT_VERBNAMES)) ||
- /* OR: character > 255 */
- c > 255 ||
- /* OR: not a # comment or white space */
- (c != CHAR_NUMBER_SIGN && (cb->ctypes[c] & ctype_space) == 0)
- ))
+#ifdef SUPPORT_UNICODE
+ /* OR: character > 255 AND not Unicode Pattern White Space */
+ (c > 255 && (c|1) != 0x200f && (c|1) != 0x2029) ||
+#endif
+ /* OR: not a # comment or isspace() white space */
+ (c < 256 && c != CHAR_NUMBER_SIGN && (cb->ctypes[c] & ctype_space) == 0
+#ifdef SUPPORT_UNICODE
+ /* and not CHAR_NEL when Unicode is supported */
+ && c != CHAR_NEL
+#endif
+ )))
{
PCRE2_SIZE verbnamelength;
@@ -2554,11 +2560,18 @@
/* Skip over whitespace and # comments in extended mode. Note that c is a
character, not a code unit, so we must not use MAX_255 to test its size
- because MAX_255 tests code units and is assumed TRUE in 8-bit mode. */
+ because MAX_255 tests code units and is assumed TRUE in 8-bit mode. The
+ whitespace characters are those designated as "Pattern White Space" by
+ Unicode, which are the isspace() characters plus CHAR_NEL (newline), which is
+ U+0085 in Unicode, plus U+200E, U+200F, U+2028, and U+2029. These are a
+ subset of space characters that match \h and \v. */
if ((options & PCRE2_EXTENDED) != 0)
{
if (c < 256 && (cb->ctypes[c] & ctype_space) != 0) continue;
+#ifdef SUPPORT_UNICODE
+ if (c == CHAR_NEL || (c|1) == 0x200f || (c|1) == 0x2029) continue;
+#endif
if (c == CHAR_NUMBER_SIGN)
{
while (ptr < ptrend)
Modified: code/trunk/testdata/testinput1
===================================================================
--- code/trunk/testdata/testinput1 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/testdata/testinput1 2018-08-03 09:38:36 UTC (rev 977)
@@ -6257,5 +6257,5 @@
\= Expect no match
aBCDEF
AbCDe f
-
+
# End of testinput1
Modified: code/trunk/testdata/testinput4
===================================================================
--- code/trunk/testdata/testinput4 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/testdata/testinput4 2018-08-03 09:38:36 UTC (rev 977)
@@ -2293,5 +2293,20 @@
/[\N{U+1234}]/utf
\x{1234}
+
+# Test the full list of Unicode "Pattern White Space" characters that are to
+# be ignored by /x. The pattern lines below may show up oddly in text editors
+# or when listed to the screen. Note that characters such as U+2002, which are
+# matched as space by \h and \v are *not* "Pattern White Space".
+/A
B/x,utf
+ AB
+
+/A B/x,utf
+ A\x{2002}B
+\= Expect no match
+ AB
+
+# -------
+
# End of testinput4
Modified: code/trunk/testdata/testinput5
===================================================================
--- code/trunk/testdata/testinput5 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/testdata/testinput5 2018-08-03 09:38:36 UTC (rev 977)
@@ -2093,4 +2093,19 @@
/\N{U}/
+# This tests the non-UTF Unicode NEL pattern whitespace character, only
+# recognized by PCRE2 with /x when there is Unicode support.
+
+/A
+??
+\x85B/x
+ AB
+
+# This tests Unicode Pattern White Space characters in verb names when they
+# are being processed with PCRE2_EXTENDED. Note: there are UTF-8 characters
+# with code points greater than 255 between A, B, and C in the pattern.
+
+/(*: AB
C)abc/x,utf,mark,alt_verbnames
+ abc
+
# End of testinput5
Modified: code/trunk/testdata/testoutput1
===================================================================
--- code/trunk/testdata/testoutput1 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/testdata/testoutput1 2018-08-03 09:38:36 UTC (rev 977)
@@ -9920,5 +9920,5 @@
No match
AbCDe f
No match
-
+
# End of testinput1
Modified: code/trunk/testdata/testoutput4
===================================================================
--- code/trunk/testdata/testoutput4 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/testdata/testoutput4 2018-08-03 09:38:36 UTC (rev 977)
@@ -3711,5 +3711,23 @@
/[\N{U+1234}]/utf
\x{1234}
0: \x{1234}
+
+# Test the full list of Unicode "Pattern White Space" characters that are to
+# be ignored by /x. The pattern lines below may show up oddly in text editors
+# or when listed to the screen. Note that characters such as U+2002, which are
+# matched as space by \h and \v are *not* "Pattern White Space".
+/A
B/x,utf
+ AB
+ 0: AB
+
+/A B/x,utf
+ A\x{2002}B
+ 0: A\x{2002}B
+\= Expect no match
+ AB
+No match
+
+# -------
+
# End of testinput4
Modified: code/trunk/testdata/testoutput5
===================================================================
--- code/trunk/testdata/testoutput5 2018-07-28 16:23:24 UTC (rev 976)
+++ code/trunk/testdata/testoutput5 2018-08-03 09:38:36 UTC (rev 977)
@@ -4758,4 +4758,22 @@
/\N{U}/
Failed: error 137 at offset 2: PCRE2 does not support \F, \L, \l, \N{name}, \U, or \u
+# This tests the non-UTF Unicode NEL pattern whitespace character, only
+# recognized by PCRE2 with /x when there is Unicode support.
+
+/A
+??
+\x85B/x
+ AB
+ 0: AB
+
+# This tests Unicode Pattern White Space characters in verb names when they
+# are being processed with PCRE2_EXTENDED. Note: there are UTF-8 characters
+# with code points greater than 255 between A, B, and C in the pattern.
+
+/(*: AB
C)abc/x,utf,mark,alt_verbnames
+ abc
+ 0: abc
+MK: ABC
+
# End of testinput5
