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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