UNLOZE/sourcemod
9
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Updated PCRE source to version 8.32 (bug 5593).

Browse Source
This commit is contained in:
Nicholas Hastings
2013-03-17 11:32:03 -04:00
parent ed6d8521e6
commit 6ce00034a2
340 changed files with 154241 additions and 63858 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tools/pcre/doc/html/pcrecompat.html
+75 -38
View File
@@ -17,23 +17,22 @@ DIFFERENCES BETWEEN PCRE AND PERL
</b><br>
<P>
This document describes the differences in the ways that PCRE and Perl handle
regular expressions. The differences described here are mainly with respect to
Perl 5.8, though PCRE versions 7.0 and later contain some features that are
expected to be in the forthcoming Perl 5.10.
regular expressions. The differences described here are with respect to Perl
versions 5.10 and above.
</P>
<P>
1. PCRE has only a subset of Perl's UTF-8 and Unicode support. Details of what
it does have are given in the
<a href="pcre.html#utf8support">section on UTF-8 support</a>
in the main
<a href="pcre.html"><b>pcre</b></a>
1. PCRE has only a subset of Perl's Unicode support. Details of what it does
have are given in the
<a href="pcreunicode.html"><b>pcreunicode</b></a>
page.
</P>
<P>
2. PCRE does not allow repeat quantifiers on lookahead assertions. Perl permits
them, but they do not mean what you might think. For example, (?!a){3} does
not assert that the next three characters are not "a". It just asserts that the
next character is not "a" three times.
2. PCRE allows repeat quantifiers only on parenthesized assertions, but they do
not mean what you might think. For example, (?!a){3} does not assert that the
next three characters are not "a". It just asserts that the next character is
not "a" three times (in principle: PCRE optimizes this to run the assertion
just once). Perl allows repeat quantifiers on other assertions such as \b, but
these do not seem to have any use.
</P>
<P>
3. Capturing subpatterns that occur inside negative lookahead assertions are
@@ -50,16 +49,22 @@ represent a binary zero.
</P>
<P>
5. The following Perl escape sequences are not supported: \l, \u, \L,
\U, and \N. In fact these are implemented by Perl's general string-handling
and are not part of its pattern matching engine. If any of these are
encountered by PCRE, an error is generated.
\U, and \N when followed by a character name or Unicode value. (\N on its
own, matching a non-newline character, is supported.) In fact these are
implemented by Perl's general string-handling and are not part of its pattern
matching engine. If any of these are encountered by PCRE, an error is
generated by default. However, if the PCRE_JAVASCRIPT_COMPAT option is set,
\U and \u are interpreted as JavaScript interprets them.
</P>
<P>
6. The Perl escape sequences \p, \P, and \X are supported only if PCRE is
built with Unicode character property support. The properties that can be
tested with \p and \P are limited to the general category properties such as
Lu and Nd, script names such as Greek or Han, and the derived properties Any
and L&.
and L&. PCRE does support the Cs (surrogate) property, which Perl does not; the
Perl documentation says "Because Perl hides the need for the user to understand
the internal representation of Unicode characters, there is no need to
implement the somewhat messy concept of surrogates."
</P>
<P>
7. PCRE does support the \Q...\E escape for quoting substrings. Characters in
@@ -79,37 +84,67 @@ The \Q...\E sequence is recognized both inside and outside character classes.
<P>
8. Fairly obviously, PCRE does not support the (?{code}) and (??{code})
constructions. However, there is support for recursive patterns. This is not
available in Perl 5.8, but will be in Perl 5.10. Also, the PCRE "callout"
available in Perl 5.8, but it is in Perl 5.10. Also, the PCRE "callout"
feature allows an external function to be called during pattern matching. See
the
<a href="pcrecallout.html"><b>pcrecallout</b></a>
documentation for details.
</P>
<P>
9. Subpatterns that are called recursively or as "subroutines" are always
treated as atomic groups in PCRE. This is like Python, but unlike Perl.
9. Subpatterns that are called as subroutines (whether or not recursively) are
always treated as atomic groups in PCRE. This is like Python, but unlike Perl.
Captured values that are set outside a subroutine call can be reference from
inside in PCRE, but not in Perl. There is a discussion that explains these
differences in more detail in the
<a href="pcrepattern.html#recursiondifference">section on recursion differences from Perl</a>
in the
<a href="pcrepattern.html"><b>pcrepattern</b></a>
page.
</P>
<P>
10. There are some differences that are concerned with the settings of captured
10. If any of the backtracking control verbs are used in an assertion or in a
subpattern that is called as a subroutine (whether or not recursively), their
effect is confined to that subpattern; it does not extend to the surrounding
pattern. This is not always the case in Perl. In particular, if (*THEN) is
present in a group that is called as a subroutine, its action is limited to
that group, even if the group does not contain any | characters. There is one
exception to this: the name from a *(MARK), (*PRUNE), or (*THEN) that is
encountered in a successful positive assertion <i>is</i> passed back when a
match succeeds (compare capturing parentheses in assertions). Note that such
subpatterns are processed as anchored at the point where they are tested.
</P>
<P>
11. There are some differences that are concerned with the settings of captured
strings when part of a pattern is repeated. For example, matching "aba" against
the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b".
</P>
<P>
11. PCRE does support Perl 5.10's backtracking verbs (*ACCEPT), (*FAIL), (*F),
(*COMMIT), (*PRUNE), (*SKIP), and (*THEN), but only in the forms without an
argument. PCRE does not support (*MARK). If (*ACCEPT) is within capturing
parentheses, PCRE does not set that capture group; this is different to Perl.
12. PCRE's handling of duplicate subpattern numbers and duplicate subpattern
names is not as general as Perl's. This is a consequence of the fact the PCRE
works internally just with numbers, using an external table to translate
between numbers and names. In particular, a pattern such as (?|(?&#60;a&#62;A)|(?&#60;b)B),
where the two capturing parentheses have the same number but different names,
is not supported, and causes an error at compile time. If it were allowed, it
would not be possible to distinguish which parentheses matched, because both
names map to capturing subpattern number 1. To avoid this confusing situation,
an error is given at compile time.
</P>
<P>
12. PCRE provides some extensions to the Perl regular expression facilities.
Perl 5.10 will include new features that are not in earlier versions, some of
which (such as named parentheses) have been in PCRE for some time. This list is
with respect to Perl 5.10:
13. Perl recognizes comments in some places that PCRE does not, for example,
between the ( and ? at the start of a subpattern. If the /x modifier is set,
Perl allows white space between ( and ? but PCRE never does, even if the
PCRE_EXTENDED option is set.
</P>
<P>
14. PCRE provides some extensions to the Perl regular expression facilities.
Perl 5.10 includes new features that are not in earlier versions of Perl, some
of which (such as named parentheses) have been in PCRE for some time. This list
is with respect to Perl 5.10:
<br>
<br>
(a) Although lookbehind assertions must match fixed length strings, each
alternative branch of a lookbehind assertion can match a different length of
string. Perl requires them all to have the same length.
(a) Although lookbehind assertions in PCRE must match fixed length strings,
each alternative branch of a lookbehind assertion can match a different length
of string. Perl requires them all to have the same length.
<br>
<br>
(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $
@@ -130,8 +165,8 @@ question mark they are.
only at the first matching position in the subject string.
<br>
<br>
(f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAPTURE
options for <b>pcre_exec()</b> have no Perl equivalents.
(f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, PCRE_NOTEMPTY_ATSTART, and
PCRE_NO_AUTO_CAPTURE options for <b>pcre_exec()</b> have no Perl equivalents.
<br>
<br>
(g) The \R escape sequence can be restricted to match only CR, LF, or CRLF
@@ -145,11 +180,13 @@ by the PCRE_BSR_ANYCRLF option.
<br>
<br>
(j) Patterns compiled by PCRE can be saved and re-used at a later time, even on
different hosts that have the other endianness.
different hosts that have the other endianness. However, this does not apply to
optimized data created by the just-in-time compiler.
<br>
<br>
(k) The alternative matching function (<b>pcre_dfa_exec()</b>) matches in a
different way and is not Perl-compatible.
(k) The alternative matching functions (<b>pcre_dfa_exec()</b>,
<b>pcre16_dfa_exec()</b> and <b>pcre32_dfa_exec()</b>,) match in a different way
and are not Perl-compatible.
<br>
<br>
(l) PCRE recognizes some special sequences such as (*CR) at the start of
@@ -170,9 +207,9 @@ Cambridge CB2 3QH, England.
REVISION
</b><br>
<P>
Last updated: 11 September 2007
Last updated: 25 August 2012
<br>
Copyright &copy; 1997-2007 University of Cambridge.
Copyright &copy; 1997-2012 University of Cambridge.
<br>
<p>
Return to the <a href="index.html">PCRE index page</a>.