pcrecompat specification

From f3bf8d3110b852b8f338898c3237d16a74360cf3 Mon Sep 17 00:00:00 2001 From: Jay Berkenbilt Date: Sat, 10 Oct 2009 17:41:30 +0000 Subject: remove files not needed for building git-svn-id: svn+q:///qpdf/trunk@767 71b93d88-0707-0410-a8cf-f5a4172ac649 --- external-libs/pcre/doc/html/pcrecompat.html | 136 ---------------------------- 1 file changed, 136 deletions(-) delete mode 100644 external-libs/pcre/doc/html/pcrecompat.html (limited to 'external-libs/pcre/doc/html/pcrecompat.html') diff --git a/external-libs/pcre/doc/html/pcrecompat.html b/external-libs/pcre/doc/html/pcrecompat.html deleted file mode 100644 index 1ec22038..00000000 --- a/external-libs/pcre/doc/html/pcrecompat.html +++ /dev/null @@ -1,136 +0,0 @@ - - -pcrecompat specification - - -This HTML document has been generated automatically from the original man page. -If there is any nonsense in it, please consult the man page, in case the -conversion went wrong.
-

DIFFERENCES FROM PERL -

-
DIFFERENCES FROM PERL
-

-This document describes the differences in the ways that PCRE and Perl handle -regular expressions. The differences described here are with respect to Perl -5.8. -

-1. PCRE does not have full UTF-8 support. Details of what it does have are -given in the -section on UTF-8 support -in the main -pcre -page. -

-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. -

-3. Capturing subpatterns that occur inside negative lookahead assertions are -counted, but their entries in the offsets vector are never set. Perl sets its -numerical variables from any such patterns that are matched before the -assertion fails to match something (thereby succeeding), but only if the -negative lookahead assertion contains just one branch. -

-4. Though binary zero characters are supported in the subject string, they are -not allowed in a pattern string because it is passed as a normal C string, -terminated by zero. The escape sequence "\0" can be used in the pattern to -represent a binary zero. -

-5. The following Perl escape sequences are not supported: \l, \u, \L, -\U, \P, \p, \N, and \X. 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. -

-6. PCRE does support the \Q...\E escape for quoting substrings. Characters in -between are treated as literals. This is slightly different from Perl in that $ -and @ are also handled as literals inside the quotes. In Perl, they cause -variable interpolation (but of course PCRE does not have variables). Note the -following examples: -

-    Pattern            PCRE matches      Perl matches
-

-    \Qabc$xyz\E        abc$xyz           abc followed by the
-                                           contents of $xyz
-    \Qabc\$xyz\E       abc\$xyz          abc\$xyz
-    \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
-

-The \Q...\E sequence is recognized both inside and outside character classes. -

-7. Fairly obviously, PCRE does not support the (?{code}) and (?p{code}) -constructions. However, there is some experimental support for recursive -patterns using the non-Perl items (?R), (?number) and (?P>name). Also, the PCRE -"callout" feature allows an external function to be called during pattern -matching. -

-8. 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". -

-9. PCRE provides some extensions to the Perl regular expression facilities: -

-(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. -

-(b) If PCRE_DOLLAR_ENDONLY is set and PCRE_MULTILINE is not set, the $ -meta-character matches only at the very end of the string. -

-(d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is -inverted, that is, by default they are not greedy, but if followed by a -question mark they are. -

-(e) PCRE_ANCHORED can be used to force a pattern to be tried only at the first -matching position in the subject string. -

-(f) The PCRE_NOTBOL, PCRE_NOTEOL, PCRE_NOTEMPTY, and PCRE_NO_AUTO_CAPTURE -options for pcre_exec() have no Perl equivalents. -

-(g) The (?R), (?number), and (?P>name) constructs allows for recursive pattern -matching (Perl can do this using the (?p{code}) construct, which PCRE cannot -support.) -

-(h) PCRE supports named capturing substrings, using the Python syntax. -

-(i) PCRE supports the possessive quantifier "++" syntax, taken from Sun's Java -package. -

-(j) The (R) condition, for testing recursion, is a PCRE extension. -

-(k) The callout facility is PCRE-specific. -