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Revision 1055 - (show annotations)
Tue Oct 16 15:53:30 2012 UTC (7 years ago) by chpe
File size: 2324 byte(s)
pcre32: Add 32-bit library

Create libpcre32 that operates on 32-bit characters (UTF-32).

This turned out to be surprisingly simple after the UTF-16 support
was introduced; mostly just extra ifdefs and adjusting and adding
some tests.
1 .TH PCRELIMITS 3 "24 June 2012" "PCRE 8.30"
3 PCRE - Perl-compatible regular expressions
5 .rs
6 .sp
7 There are some size limitations in PCRE but it is hoped that they will never in
8 practice be relevant.
9 .P
10 The maximum length of a compiled pattern is approximately 64K data units (bytes
11 for the 8-bit library, 32-bit units for the 32-bit library, and 32-bit units for
12 the 32-bit library) if PCRE is compiled with the default internal linkage size
13 of 2 bytes. If you want to process regular expressions that are truly enormous,
14 you can compile PCRE with an internal linkage size of 3 or 4 (when building the
15 16-bit or 32-bit library, 3 is rounded up to 4). See the \fBREADME\fP file in
16 the source distribution and the
17 .\" HREF
18 \fBpcrebuild\fP
19 .\"
20 documentation for details. In these cases the limit is substantially larger.
21 However, the speed of execution is slower.
22 .P
23 All values in repeating quantifiers must be less than 65536.
24 .P
25 There is no limit to the number of parenthesized subpatterns, but there can be
26 no more than 65535 capturing subpatterns.
27 .P
28 There is a limit to the number of forward references to subsequent subpatterns
29 of around 200,000. Repeated forward references with fixed upper limits, for
30 example, (?2){0,100} when subpattern number 2 is to the right, are included in
31 the count. There is no limit to the number of backward references.
32 .P
33 The maximum length of name for a named subpattern is 32 characters, and the
34 maximum number of named subpatterns is 10000.
35 .P
36 The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb
37 is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit library.
38 .P
39 The maximum length of a subject string is the largest positive number that an
40 integer variable can hold. However, when using the traditional matching
41 function, PCRE uses recursion to handle subpatterns and indefinite repetition.
42 This means that the available stack space may limit the size of a subject
43 string that can be processed by certain patterns. For a discussion of stack
44 issues, see the
45 .\" HREF
46 \fBpcrestack\fP
47 .\"
48 documentation.
49 .
50 .
52 .rs
53 .sp
54 .nf
55 Philip Hazel
56 University Computing Service
57 Cambridge CB2 3QH, England.
58 .fi
59 .
60 .
62 .rs
63 .sp
64 .nf
65 Last updated: 04 May 2012
66 Copyright (c) 1997-2012 University of Cambridge.
67 .fi

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