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revision 92 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 93 by nigel, Sat Feb 24 21:41:42 2007 UTC
# Line 23  man page, in case the conversion went wr Line 23  man page, in case the conversion went wr
23  <P>  <P>
24  The PCRE library is a set of functions that implement regular expression  The PCRE library is a set of functions that implement regular expression
25  pattern matching using the same syntax and semantics as Perl, with just a few  pattern matching using the same syntax and semantics as Perl, with just a few
26  differences. The current implementation of PCRE (release 6.x) corresponds  differences. (Certain features that appeared in Python and PCRE before they
27  approximately with Perl 5.8, including support for UTF-8 encoded strings and  appeared in Perl are also available using the Python syntax.)
 Unicode general category properties. However, this support has to be explicitly  
 enabled; it is not the default.  
28  </P>  </P>
29  <P>  <P>
30  In addition to the Perl-compatible matching function, PCRE also contains an  The current implementation of PCRE (release 7.x) corresponds approximately with
31    Perl 5.10, including support for UTF-8 encoded strings and Unicode general
32    category properties. However, UTF-8 and Unicode support has to be explicitly
33    enabled; it is not the default. The Unicode tables correspond to Unicode
34    release 5.0.0.
35    </P>
36    <P>
37    In addition to the Perl-compatible matching function, PCRE contains an
38  alternative matching function that matches the same compiled patterns in a  alternative matching function that matches the same compiled patterns in a
39  different way. In certain circumstances, the alternative function has some  different way. In certain circumstances, the alternative function has some
40  advantages. For a discussion of the two matching algorithms, see the  advantages. For a discussion of the two matching algorithms, see the
# Line 114  internal linkage size of 3 or 4 (see the Line 119  internal linkage size of 3 or 4 (see the
119  distribution and the  distribution and the
120  <a href="pcrebuild.html"><b>pcrebuild</b></a>  <a href="pcrebuild.html"><b>pcrebuild</b></a>
121  documentation for details). In these cases the limit is substantially larger.  documentation for details). In these cases the limit is substantially larger.
122  However, the speed of execution will be slower.  However, the speed of execution is slower.
123  </P>  </P>
124  <P>  <P>
125  All values in repeating quantifiers must be less than 65536. The maximum  All values in repeating quantifiers must be less than 65536. The maximum
# Line 122  compiled length of subpattern with an ex Line 127  compiled length of subpattern with an ex
127  maximum number of capturing subpatterns is 65535.  maximum number of capturing subpatterns is 65535.
128  </P>  </P>
129  <P>  <P>
130  There is no limit to the number of non-capturing subpatterns, but the maximum  There is no limit to the number of parenthesized subpatterns, but there can be
131  depth of nesting of all kinds of parenthesized subpattern, including capturing  no more than 65535 capturing subpatterns.
 subpatterns, assertions, and other types of subpattern, is 200.  
132  </P>  </P>
133  <P>  <P>
134  The maximum length of name for a named subpattern is 32, and the maximum number  The maximum length of name for a named subpattern is 32 characters, and the
135  of named subpatterns is 10000.  maximum number of named subpatterns is 10000.
136  </P>  </P>
137  <P>  <P>
138  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
# Line 158  instead of just strings of bytes. Line 162  instead of just strings of bytes.
162  <P>  <P>
163  If you compile PCRE with UTF-8 support, but do not use it at run time, the  If you compile PCRE with UTF-8 support, but do not use it at run time, the
164  library will be a bit bigger, but the additional run time overhead is limited  library will be a bit bigger, but the additional run time overhead is limited
165  to testing the PCRE_UTF8 flag in several places, so should not be very large.  to testing the PCRE_UTF8 flag occasionally, so should not be very big.
166  </P>  </P>
167  <P>  <P>
168  If PCRE is built with Unicode character property support (which implies UTF-8  If PCRE is built with Unicode character property support (which implies UTF-8
# Line 238  Philip Hazel Line 242  Philip Hazel
242  <br>  <br>
243  University Computing Service,  University Computing Service,
244  <br>  <br>
245  Cambridge CB2 3QG, England.  Cambridge CB2 3QH, England.
246  </P>  </P>
247  <P>  <P>
248  Putting an actual email address here seems to have been a spam magnet, so I've  Putting an actual email address here seems to have been a spam magnet, so I've
249  taken it away. If you want to email me, use my initial and surname, separated  taken it away. If you want to email me, use my initial and surname, separated
250  by a dot, at the domain ucs.cam.ac.uk.  by a dot, at the domain ucs.cam.ac.uk.
251  Last updated: 05 June 2006  Last updated: 23 November 2006
252  <br>  <br>
253  Copyright &copy; 1997-2006 University of Cambridge.  Copyright &copy; 1997-2006 University of Cambridge.
254  <p>  <p>

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