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1.1       misho       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
1.1.1.2 ! misho      10: The maximum length of a compiled pattern is approximately 64K data units (bytes
        !            11: for the 8-bit library, 16-bit units for the 16-bit library) if PCRE is compiled
        !            12: with the default internal linkage size of 2 bytes. If you want to process
1.1       misho      13: regular expressions that are truly enormous, you can compile PCRE with an
1.1.1.2 ! misho      14: internal linkage size of 3 or 4 (when building the 16-bit library, 3 is rounded
        !            15: up to 4). See the \fBREADME\fP file in the source distribution and the
1.1       misho      16: .\" HREF
                     17: \fBpcrebuild\fP
                     18: .\"
1.1.1.2 ! misho      19: documentation for details. In these cases the limit is substantially larger.
1.1       misho      20: However, the speed of execution is slower.
                     21: .P
                     22: All values in repeating quantifiers must be less than 65536.
                     23: .P
                     24: There is no limit to the number of parenthesized subpatterns, but there can be
                     25: no more than 65535 capturing subpatterns.
                     26: .P
                     27: There is a limit to the number of forward references to subsequent subpatterns
                     28: of around 200,000. Repeated forward references with fixed upper limits, for
                     29: example, (?2){0,100} when subpattern number 2 is to the right, are included in
                     30: the count. There is no limit to the number of backward references.
                     31: .P
                     32: The maximum length of name for a named subpattern is 32 characters, and the
                     33: maximum number of named subpatterns is 10000.
                     34: .P
                     35: The maximum length of a subject string is the largest positive number that an
                     36: integer variable can hold. However, when using the traditional matching
                     37: function, PCRE uses recursion to handle subpatterns and indefinite repetition.
                     38: This means that the available stack space may limit the size of a subject
                     39: string that can be processed by certain patterns. For a discussion of stack
                     40: issues, see the
                     41: .\" HREF
                     42: \fBpcrestack\fP
                     43: .\"
                     44: documentation.
                     45: .
                     46: .
                     47: .SH AUTHOR
                     48: .rs
                     49: .sp
                     50: .nf
                     51: Philip Hazel
                     52: University Computing Service
                     53: Cambridge CB2 3QH, England.
                     54: .fi
                     55: .
                     56: .
                     57: .SH REVISION
                     58: .rs
                     59: .sp
                     60: .nf
1.1.1.2 ! misho      61: Last updated: 08 January 2012
        !            62: Copyright (c) 1997-2012 University of Cambridge.
1.1       misho      63: .fi