Annotation of embedaddon/pcre/doc/pcrelimits.3, revision 1.1
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
! 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
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