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revision 96 by nigel, Fri Mar 2 13:10:43 2007 UTC revision 211 by ph10, Thu Aug 9 09:52:43 2007 UTC
# Line 6  PCRE - Perl-compatible regular expressio Line 6  PCRE - Perl-compatible regular expressio
6  .sp  .sp
7  This document describes the differences in the ways that PCRE and Perl handle  This document describes the differences in the ways that PCRE and Perl handle
8  regular expressions. The differences described here are mainly with respect to  regular expressions. The differences described here are mainly with respect to
9  Perl 5.8, though PCRE version 7.0 contains some features that are expected to  Perl 5.8, though PCRE versions 7.0 and later contain some features that are
10  be in the forthcoming Perl 5.10.  expected to be in the forthcoming Perl 5.10.
11  .P  .P
12  1. PCRE has only a subset of Perl's UTF-8 and Unicode support. Details of what  1. PCRE has only a subset of Perl's UTF-8 and Unicode support. Details of what
13  it does have are given in the  it does have are given in the
# Line 81  treated as atomic groups in PCRE. This i Line 81  treated as atomic groups in PCRE. This i
81  strings when part of a pattern is repeated. For example, matching "aba" against  strings when part of a pattern is repeated. For example, matching "aba" against
82  the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b".  the pattern /^(a(b)?)+$/ in Perl leaves $2 unset, but in PCRE it is set to "b".
83  .P  .P
84  11. PCRE provides some extensions to the Perl regular expression facilities.  11. PCRE does support Perl 5.10's backtracking verbs (*ACCEPT), (*FAIL), (*F),
85    (*COMMIT), (*PRUNE), (*SKIP), and (*THEN), but only in the forms without an
86    argument. PCRE does not support (*MARK). If (*ACCEPT) is within capturing
87    parentheses, PCRE does not set that capture group; this is different to Perl.
88    .P
89    12. PCRE provides some extensions to the Perl regular expression facilities.
90  Perl 5.10 will include new features that are not in earlier versions, some of  Perl 5.10 will include new features that are not in earlier versions, some of
91  which (such as named parentheses) have been in PCRE for some time. This list is  which (such as named parentheses) have been in PCRE for some time. This list is
92  with respect to Perl 5.10:  with respect to Perl 5.10:
# Line 94  string. Perl requires them all to have t Line 99  string. Perl requires them all to have t
99  meta-character matches only at the very end of the string.  meta-character matches only at the very end of the string.
100  .sp  .sp
101  (c) If PCRE_EXTRA is set, a backslash followed by a letter with no special  (c) If PCRE_EXTRA is set, a backslash followed by a letter with no special
102  meaning is faulted. Otherwise, like Perl, the backslash is ignored. (Perl can  meaning is faulted. Otherwise, like Perl, the backslash is quietly ignored.
103  be made to issue a warning.)  (Perl can be made to issue a warning.)
104  .sp  .sp
105  (d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is  (d) If PCRE_UNGREEDY is set, the greediness of the repetition quantifiers is
106  inverted, that is, by default they are not greedy, but if followed by a  inverted, that is, by default they are not greedy, but if followed by a
# Line 116  different hosts that have the other endi Line 121  different hosts that have the other endi
121  .sp  .sp
122  (j) The alternative matching function (\fBpcre_dfa_exec()\fP) matches in a  (j) The alternative matching function (\fBpcre_dfa_exec()\fP) matches in a
123  different way and is not Perl-compatible.  different way and is not Perl-compatible.
124  .P  .
125  .in 0  .
126  Last updated: 28 November 2006  .SH AUTHOR
127  .br  .rs
128  Copyright (c) 1997-2006 University of Cambridge.  .sp
129    .nf
130    Philip Hazel
131    University Computing Service
132    Cambridge CB2 3QH, England.
133    .fi
134    .
135    .
136    .SH REVISION
137    .rs
138    .sp
139    .nf
140    Last updated: 08 August 2007
141    Copyright (c) 1997-2007 University of Cambridge.
142    .fi
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