/[pcre]/code/trunk/doc/pcrelimits.3
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revision 678 by ph10, Sun Aug 28 15:23:03 2011 UTC revision 858 by ph10, Sun Jan 8 17:55:38 2012 UTC
# Line 7  PCRE - Perl-compatible regular expressio Line 7  PCRE - Perl-compatible regular expressio
7  There are some size limitations in PCRE but it is hoped that they will never in  There are some size limitations in PCRE but it is hoped that they will never in
8  practice be relevant.  practice be relevant.
9  .P  .P
10  The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is  The maximum length of a compiled pattern is approximately 64K data units (bytes
11  compiled with the default internal linkage size of 2. If you want to process  for the 8-bit library, 16-bit units for the 16-bit library) if PCRE is compiled
12    with the default internal linkage size of 2 bytes. If you want to process
13  regular expressions that are truly enormous, you can compile PCRE with an  regular expressions that are truly enormous, you can compile PCRE with an
14  internal linkage size of 3 or 4 (see the \fBREADME\fP file in the source  internal linkage size of 3 or 4 (when building the 16-bit library, 3 is rounded
15  distribution and the  up to 4). See the \fBREADME\fP file in the source distribution and the
16  .\" HREF  .\" HREF
17  \fBpcrebuild\fP  \fBpcrebuild\fP
18  .\"  .\"
19  documentation for details). In these cases the limit is substantially larger.  documentation for details. In these cases the limit is substantially larger.
20  However, the speed of execution is slower.  However, the speed of execution is slower.
21  .P  .P
22  All values in repeating quantifiers must be less than 65536.  All values in repeating quantifiers must be less than 65536.
# Line 23  All values in repeating quantifiers must Line 24  All values in repeating quantifiers must
24  There is no limit to the number of parenthesized subpatterns, but there can be  There is no limit to the number of parenthesized subpatterns, but there can be
25  no more than 65535 capturing subpatterns.  no more than 65535 capturing subpatterns.
26  .P  .P
27    There is a limit to the number of forward references to subsequent subpatterns
28    of around 200,000. Repeated forward references with fixed upper limits, for
29    example, (?2){0,100} when subpattern number 2 is to the right, are included in
30    the count. There is no limit to the number of backward references.
31    .P
32  The maximum length of name for a named subpattern is 32 characters, and the  The maximum length of name for a named subpattern is 32 characters, and the
33  maximum number of named subpatterns is 10000.  maximum number of named subpatterns is 10000.
34  .P  .P
# Line 52  Cambridge CB2 3QH, England. Line 58  Cambridge CB2 3QH, England.
58  .rs  .rs
59  .sp  .sp
60  .nf  .nf
61  Last updated: 24 August 2011  Last updated: 08 January 2012
62  Copyright (c) 1997-2011 University of Cambridge.  Copyright (c) 1997-2012 University of Cambridge.
63  .fi  .fi

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