Annotation of embedaddon/pcre/doc/pcrelimits.3, revision 1.1.1.4
1.1.1.4 ! misho 1: .TH PCRELIMITS 3 "24 June 2012" "PCRE 8.30"
1.1 misho 2: .SH NAME
3: PCRE - Perl-compatible regular expressions
4: .SH "SIZE AND OTHER LIMITATIONS"
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
1.1.1.2 misho 10: The maximum length of a compiled pattern is approximately 64K data units (bytes
1.1.1.4 ! misho 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
1.1 misho 17: .\" HREF
18: \fBpcrebuild\fP
19: .\"
1.1.1.2 misho 20: documentation for details. In these cases the limit is substantially larger.
1.1 misho 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
1.1.1.3 misho 36: The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb
1.1.1.4 ! misho 37: is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit library.
1.1.1.3 misho 38: .P
1.1 misho 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: .
51: .SH AUTHOR
52: .rs
53: .sp
54: .nf
55: Philip Hazel
56: University Computing Service
57: Cambridge CB2 3QH, England.
58: .fi
59: .
60: .
61: .SH REVISION
62: .rs
63: .sp
64: .nf
1.1.1.3 misho 65: Last updated: 04 May 2012
1.1.1.2 misho 66: Copyright (c) 1997-2012 University of Cambridge.
1.1 misho 67: .fi
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