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pcre

    1: .TH PCRELIMITS 3
    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
   10: The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is
   11: compiled with the default internal linkage size of 2. If you want to process
   12: regular expressions that are truly enormous, you can compile PCRE with an
   13: internal linkage size of 3 or 4 (see the \fBREADME\fP file in the source
   14: distribution and the
   15: .\" HREF
   16: \fBpcrebuild\fP
   17: .\"
   18: documentation for details). In these cases the limit is substantially larger.
   19: However, the speed of execution is slower.
   20: .P
   21: All values in repeating quantifiers must be less than 65536.
   22: .P
   23: There is no limit to the number of parenthesized subpatterns, but there can be
   24: no more than 65535 capturing subpatterns.
   25: .P
   26: There is a limit to the number of forward references to subsequent subpatterns
   27: of around 200,000. Repeated forward references with fixed upper limits, for
   28: example, (?2){0,100} when subpattern number 2 is to the right, are included in
   29: the count. There is no limit to the number of backward references.
   30: .P
   31: The maximum length of name for a named subpattern is 32 characters, and the
   32: maximum number of named subpatterns is 10000.
   33: .P
   34: The maximum length of a subject string is the largest positive number that an
   35: integer variable can hold. However, when using the traditional matching
   36: function, PCRE uses recursion to handle subpatterns and indefinite repetition.
   37: This means that the available stack space may limit the size of a subject
   38: string that can be processed by certain patterns. For a discussion of stack
   39: issues, see the
   40: .\" HREF
   41: \fBpcrestack\fP
   42: .\"
   43: documentation.
   44: .
   45: .
   46: .SH AUTHOR
   47: .rs
   48: .sp
   49: .nf
   50: Philip Hazel
   51: University Computing Service
   52: Cambridge CB2 3QH, England.
   53: .fi
   54: .
   55: .
   56: .SH REVISION
   57: .rs
   58: .sp
   59: .nf
   60: Last updated: 30 November 2011
   61: Copyright (c) 1997-2011 University of Cambridge.
   62: .fi