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.TH PCRELIMITS 3 | .TH PCRELIMITS 3 "05 November 2013" "PCRE 8.34" |
.SH NAME |
.SH NAME |
PCRE - Perl-compatible regular expressions |
PCRE - Perl-compatible regular expressions |
.SH "SIZE AND OTHER LIMITATIONS" |
.SH "SIZE AND OTHER LIMITATIONS" |
Line 7 PCRE - Perl-compatible regular expressions
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Line 7 PCRE - Perl-compatible regular expressions
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There are some size limitations in PCRE but it is hoped that they will never in |
There are some size limitations in PCRE but it is hoped that they will never in |
practice be relevant. |
practice be relevant. |
.P |
.P |
The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is | The maximum length of a compiled pattern is approximately 64K data units (bytes |
compiled with the default internal linkage size of 2. If you want to process | for the 8-bit library, 16-bit units for the 16-bit library, and 32-bit units for |
regular expressions that are truly enormous, you can compile PCRE with an | the 32-bit library) if PCRE is compiled with the default internal linkage size, |
internal linkage size of 3 or 4 (see the \fBREADME\fP file in the source | which is 2 bytes for the 8-bit and 16-bit libraries, and 4 bytes for the 32-bit |
distribution and the | library. If you want to process regular expressions that are truly enormous, |
| you can compile PCRE with an internal linkage size of 3 or 4 (when building the |
| 16-bit or 32-bit library, 3 is rounded up to 4). See the \fBREADME\fP file in |
| the source distribution and the |
.\" HREF |
.\" HREF |
\fBpcrebuild\fP |
\fBpcrebuild\fP |
.\" |
.\" |
documentation for details). In these cases the limit is substantially larger. | documentation for details. In these cases the limit is substantially larger. |
However, the speed of execution is slower. |
However, the speed of execution is slower. |
.P |
.P |
All values in repeating quantifiers must be less than 65536. |
All values in repeating quantifiers must be less than 65536. |
.P |
.P |
There is no limit to the number of parenthesized subpatterns, but there can be |
There is no limit to the number of parenthesized subpatterns, but there can be |
no more than 65535 capturing subpatterns. | no more than 65535 capturing subpatterns. There is, however, a limit to the |
| depth of nesting of parenthesized subpatterns of all kinds. This is imposed in |
| order to limit the amount of system stack used at compile time. The limit can |
| be specified when PCRE is built; the default is 250. |
.P |
.P |
There is a limit to the number of forward references to subsequent subpatterns |
There is a limit to the number of forward references to subsequent subpatterns |
of around 200,000. Repeated forward references with fixed upper limits, for |
of around 200,000. Repeated forward references with fixed upper limits, for |
Line 31 the count. There is no limit to the number of backward
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Line 37 the count. There is no limit to the number of backward
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The maximum length of name for a named subpattern is 32 characters, and the |
The maximum length of name for a named subpattern is 32 characters, and the |
maximum number of named subpatterns is 10000. |
maximum number of named subpatterns is 10000. |
.P |
.P |
|
The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb |
|
is 255 for the 8-bit library and 65535 for the 16-bit and 32-bit libraries. |
|
.P |
The maximum length of a subject string is the largest positive number that an |
The maximum length of a subject string is the largest positive number that an |
integer variable can hold. However, when using the traditional matching |
integer variable can hold. However, when using the traditional matching |
function, PCRE uses recursion to handle subpatterns and indefinite repetition. |
function, PCRE uses recursion to handle subpatterns and indefinite repetition. |
Line 57 Cambridge CB2 3QH, England.
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Line 66 Cambridge CB2 3QH, England.
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.rs |
.rs |
.sp |
.sp |
.nf |
.nf |
Last updated: 30 November 2011 | Last updated: 05 November 2013 |
Copyright (c) 1997-2011 University of Cambridge. | Copyright (c) 1997-2013 University of Cambridge. |
.fi |
.fi |