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revision 654 by ph10, Tue Aug 2 11:00:40 2011 UTC revision 724 by ph10, Sun Oct 9 16:23:45 2011 UTC
# Line 10  versions 5.10 and above. Line 10  versions 5.10 and above.
10  .P  .P
11  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
12  it does have are given in the  it does have are given in the
 .\" HTML <a href="pcre.html#utf8support">  
 .\" </a>  
 section on UTF-8 support  
 .\"  
 in the main  
13  .\" HREF  .\" HREF
14  \fBpcre\fP  \fBpcreunicode\fP
15  .\"  .\"
16  page.  page.
17  .P  .P
# Line 84  the Line 79  the
79  .\"  .\"
80  documentation for details.  documentation for details.
81  .P  .P
82  10. Subpatterns that are called recursively or as "subroutines" are always  10. Subpatterns that are called as subroutines (whether or not recursively) are
83  treated as atomic groups in PCRE. This is like Python, but unlike Perl. There  always treated as atomic groups in PCRE. This is like Python, but unlike Perl.
84  is a discussion of an example that explains this in more detail in the  Captured values that are set outside a subroutine call can be reference from
85    inside in PCRE, but not in Perl. There is a discussion that explains these
86    differences in more detail in the
87  .\" HTML <a href="pcrepattern.html#recursiondifference">  .\" HTML <a href="pcrepattern.html#recursiondifference">
88  .\" </a>  .\" </a>
89  section on recursion differences from Perl  section on recursion differences from Perl
# Line 97  in the Line 94  in the
94  .\"  .\"
95  page.  page.
96  .P  .P
97  11. There are some differences that are concerned with the settings of captured  11. If (*THEN) is present in a group that is called as a subroutine, its action
98    is limited to that group, even if the group does not contain any | characters.
99    .P
100    12. There are some differences that are concerned with the settings of captured
101  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
102  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".
103  .P  .P
104  12. PCRE's handling of duplicate subpattern numbers and duplicate subpattern  13. PCRE's handling of duplicate subpattern numbers and duplicate subpattern
105  names is not as general as Perl's. This is a consequence of the fact the PCRE  names is not as general as Perl's. This is a consequence of the fact the PCRE
106  works internally just with numbers, using an external table to translate  works internally just with numbers, using an external table to translate
107  between numbers and names. In particular, a pattern such as (?|(?<a>A)|(?<b)B),  between numbers and names. In particular, a pattern such as (?|(?<a>A)|(?<b)B),
# Line 111  would not be possible to distinguish whi Line 111  would not be possible to distinguish whi
111  names map to capturing subpattern number 1. To avoid this confusing situation,  names map to capturing subpattern number 1. To avoid this confusing situation,
112  an error is given at compile time.  an error is given at compile time.
113  .P  .P
114  13. Perl recognizes comments in some places that PCRE does not, for example,  14. Perl recognizes comments in some places that PCRE does not, for example,
115  between the ( and ? at the start of a subpattern. If the /x modifier is set,  between the ( and ? at the start of a subpattern. If the /x modifier is set,
116  Perl allows whitespace between ( and ? but PCRE never does, even if the  Perl allows whitespace between ( and ? but PCRE never does, even if the
117  PCRE_EXTENDED option is set.  PCRE_EXTENDED option is set.
118  .P  .P
119  14. PCRE provides some extensions to the Perl regular expression facilities.  15. PCRE provides some extensions to the Perl regular expression facilities.
120  Perl 5.10 includes new features that are not in earlier versions of Perl, some  Perl 5.10 includes new features that are not in earlier versions of Perl, some
121  of which (such as named parentheses) have been in PCRE for some time. This list  of which (such as named parentheses) have been in PCRE for some time. This list
122  is with respect to Perl 5.10:  is with respect to Perl 5.10:
# Line 150  by the PCRE_BSR_ANYCRLF option. Line 150  by the PCRE_BSR_ANYCRLF option.
150  (i) The partial matching facility is PCRE-specific.  (i) The partial matching facility is PCRE-specific.
151  .sp  .sp
152  (j) Patterns compiled by PCRE can be saved and re-used at a later time, even on  (j) Patterns compiled by PCRE can be saved and re-used at a later time, even on
153  different hosts that have the other endianness.  different hosts that have the other endianness. However, this does not apply to
154    optimized data created by the just-in-time compiler.
155  .sp  .sp
156  (k) The alternative matching function (\fBpcre_dfa_exec()\fP) matches in a  (k) The alternative matching function (\fBpcre_dfa_exec()\fP) matches in a
157  different way and is not Perl-compatible.  different way and is not Perl-compatible.
# Line 173  Cambridge CB2 3QH, England. Line 174  Cambridge CB2 3QH, England.
174  .rs  .rs
175  .sp  .sp
176  .nf  .nf
177  Last updated: 24 July 2011  Last updated: 09 October 2011
178  Copyright (c) 1997-2011 University of Cambridge.  Copyright (c) 1997-2011 University of Cambridge.
179  .fi  .fi

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