Annotation of embedaddon/pcre/doc/html/pcrelimits.html, revision 1.1.1.4
1.1 misho 1: <html>
2: <head>
3: <title>pcrelimits specification</title>
4: </head>
5: <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6: <h1>pcrelimits man page</h1>
7: <p>
8: Return to the <a href="index.html">PCRE index page</a>.
9: </p>
10: <p>
11: This page is part of the PCRE HTML documentation. It was generated automatically
12: from the original man page. If there is any nonsense in it, please consult the
13: man page, in case the conversion went wrong.
14: <br>
15: <br><b>
16: SIZE AND OTHER LIMITATIONS
17: </b><br>
18: <P>
19: There are some size limitations in PCRE but it is hoped that they will never in
20: practice be relevant.
21: </P>
22: <P>
1.1.1.2 misho 23: The maximum length of a compiled pattern is approximately 64K data units (bytes
1.1.1.4 ! misho 24: for the 8-bit library, 32-bit units for the 32-bit library, and 32-bit units for
! 25: the 32-bit library) if PCRE is compiled with the default internal linkage size
! 26: of 2 bytes. If you want to process regular expressions that are truly enormous,
! 27: you can compile PCRE with an internal linkage size of 3 or 4 (when building the
! 28: 16-bit or 32-bit library, 3 is rounded up to 4). See the <b>README</b> file in
! 29: the source distribution and the
1.1 misho 30: <a href="pcrebuild.html"><b>pcrebuild</b></a>
1.1.1.2 misho 31: documentation for details. In these cases the limit is substantially larger.
1.1 misho 32: However, the speed of execution is slower.
33: </P>
34: <P>
35: All values in repeating quantifiers must be less than 65536.
36: </P>
37: <P>
38: There is no limit to the number of parenthesized subpatterns, but there can be
39: no more than 65535 capturing subpatterns.
40: </P>
41: <P>
42: There is a limit to the number of forward references to subsequent subpatterns
43: of around 200,000. Repeated forward references with fixed upper limits, for
44: example, (?2){0,100} when subpattern number 2 is to the right, are included in
45: the count. There is no limit to the number of backward references.
46: </P>
47: <P>
48: The maximum length of name for a named subpattern is 32 characters, and the
49: maximum number of named subpatterns is 10000.
50: </P>
51: <P>
1.1.1.3 misho 52: The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb
1.1.1.4 ! misho 53: is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit library.
1.1.1.3 misho 54: </P>
55: <P>
1.1 misho 56: The maximum length of a subject string is the largest positive number that an
57: integer variable can hold. However, when using the traditional matching
58: function, PCRE uses recursion to handle subpatterns and indefinite repetition.
59: This means that the available stack space may limit the size of a subject
60: string that can be processed by certain patterns. For a discussion of stack
61: issues, see the
62: <a href="pcrestack.html"><b>pcrestack</b></a>
63: documentation.
64: </P>
65: <br><b>
66: AUTHOR
67: </b><br>
68: <P>
69: Philip Hazel
70: <br>
71: University Computing Service
72: <br>
73: Cambridge CB2 3QH, England.
74: <br>
75: </P>
76: <br><b>
77: REVISION
78: </b><br>
79: <P>
1.1.1.3 misho 80: Last updated: 04 May 2012
1.1 misho 81: <br>
1.1.1.2 misho 82: Copyright © 1997-2012 University of Cambridge.
1.1 misho 83: <br>
84: <p>
85: Return to the <a href="index.html">PCRE index page</a>.
86: </p>
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