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revision 83 by nigel, Sat Feb 24 21:41:06 2007 UTC revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC
# Line 95  follows: Line 95  follows:
95    pcreposix         the POSIX-compatible C API    pcreposix         the POSIX-compatible C API
96    pcreprecompile    details of saving and re-using precompiled patterns    pcreprecompile    details of saving and re-using precompiled patterns
97    pcresample        discussion of the sample program    pcresample        discussion of the sample program
98      pcrestack         discussion of stack usage
99    pcretest          description of the <b>pcretest</b> testing command    pcretest          description of the <b>pcretest</b> testing command
100  </pre>  </pre>
101  In addition, in the "man" and HTML formats, there is a short page for each  In addition, in the "man" and HTML formats, there is a short page for each
# Line 116  documentation for details). In these cas Line 117  documentation for details). In these cas
117  However, the speed of execution will be slower.  However, the speed of execution will be slower.
118  </P>  </P>
119  <P>  <P>
120  All values in repeating quantifiers must be less than 65536.  All values in repeating quantifiers must be less than 65536. The maximum
121  The maximum number of capturing subpatterns is 65535.  compiled length of subpattern with an explicit repeat count is 30000 bytes. The
122    maximum number of capturing subpatterns is 65535.
123  </P>  </P>
124  <P>  <P>
125  There is no limit to the number of non-capturing subpatterns, but the maximum  There is no limit to the number of non-capturing subpatterns, but the maximum
# Line 125  depth of nesting of all kinds of parenth Line 127  depth of nesting of all kinds of parenth
127  subpatterns, assertions, and other types of subpattern, is 200.  subpatterns, assertions, and other types of subpattern, is 200.
128  </P>  </P>
129  <P>  <P>
130    The maximum length of name for a named subpattern is 32, and the maximum number
131    of named subpatterns is 10000.
132    </P>
133    <P>
134  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
135  integer variable can hold. However, when using the traditional matching  integer variable can hold. However, when using the traditional matching
136  function, PCRE uses recursion to handle subpatterns and indefinite repetition.  function, PCRE uses recursion to handle subpatterns and indefinite repetition.
137  This means that the available stack space may limit the size of a subject  This means that the available stack space may limit the size of a subject
138  string that can be processed by certain patterns.  string that can be processed by certain patterns. For a discussion of stack
139    issues, see the
140    <a href="pcrestack.html"><b>pcrestack</b></a>
141    documentation.
142  <a name="utf8support"></a></P>  <a name="utf8support"></a></P>
143  <br><a name="SEC4" href="#TOC1">UTF-8 AND UNICODE PROPERTY SUPPORT</a><br>  <br><a name="SEC4" href="#TOC1">UTF-8 AND UNICODE PROPERTY SUPPORT</a><br>
144  <P>  <P>
# Line 156  If PCRE is built with Unicode character Line 165  If PCRE is built with Unicode character
165  support), the escape sequences \p{..}, \P{..}, and \X are supported.  support), the escape sequences \p{..}, \P{..}, and \X are supported.
166  The available properties that can be tested are limited to the general  The available properties that can be tested are limited to the general
167  category properties such as Lu for an upper case letter or Nd for a decimal  category properties such as Lu for an upper case letter or Nd for a decimal
168  number. A full list is given in the  number, the Unicode script names such as Arabic or Han, and the derived
169    properties Any and L&. A full list is given in the
170  <a href="pcrepattern.html"><b>pcrepattern</b></a>  <a href="pcrepattern.html"><b>pcrepattern</b></a>
171  documentation. The PCRE library is increased in size by about 90K when Unicode  documentation. Only the short names for properties are supported. For example,
172  property support is included.  \p{L} matches a letter. Its Perl synonym, \p{Letter}, is not supported.
173    Furthermore, in Perl, many properties may optionally be prefixed by "Is", for
174    compatibility with Perl 5.6. PCRE does not support this.
175  </P>  </P>
176  <P>  <P>
177  The following comments apply when PCRE is running in UTF-8 mode:  The following comments apply when PCRE is running in UTF-8 mode:
# Line 177  PCRE when PCRE_NO_UTF8_CHECK is set, the Line 189  PCRE when PCRE_NO_UTF8_CHECK is set, the
189  may crash.  may crash.
190  </P>  </P>
191  <P>  <P>
192  2. In a pattern, the escape sequence \x{...}, where the contents of the braces  2. An unbraced hexadecimal escape sequence (such as \xb3) matches a two-byte
193  is a string of hexadecimal digits, is interpreted as a UTF-8 character whose  UTF-8 character if the value is greater than 127.
 code number is the given hexadecimal number, for example: \x{1234}. If a  
 non-hexadecimal digit appears between the braces, the item is not recognized.  
 This escape sequence can be used either as a literal, or within a character  
 class.  
194  </P>  </P>
195  <P>  <P>
196  3. The original hexadecimal escape sequence, \xhh, matches a two-byte UTF-8  3. Octal numbers up to \777 are recognized, and match two-byte UTF-8
197  character if the value is greater than 127.  characters for values greater than \177.
198  </P>  </P>
199  <P>  <P>
200  4. Repeat quantifiers apply to complete UTF-8 characters, not to individual  4. Repeat quantifiers apply to complete UTF-8 characters, not to individual
# Line 219  than 128, unless PCRE is built with Unic Line 227  than 128, unless PCRE is built with Unic
227  property support is available, PCRE still uses its own character tables when  property support is available, PCRE still uses its own character tables when
228  checking the case of low-valued characters, so as not to degrade performance.  checking the case of low-valued characters, so as not to degrade performance.
229  The Unicode property information is used only for characters with higher  The Unicode property information is used only for characters with higher
230  values.  values. Even when Unicode property support is available, PCRE supports
231    case-insensitive matching only when there is a one-to-one mapping between a
232    letter's cases. There are a small number of many-to-one mappings in Unicode;
233    these are not supported by PCRE.
234  </P>  </P>
235  <br><a name="SEC5" href="#TOC1">AUTHOR</a><br>  <br><a name="SEC5" href="#TOC1">AUTHOR</a><br>
236  <P>  <P>
# Line 233  Cambridge CB2 3QG, England. Line 244  Cambridge CB2 3QG, England.
244  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
245  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
246  by a dot, at the domain ucs.cam.ac.uk.  by a dot, at the domain ucs.cam.ac.uk.
247  Last updated: 07 March 2005  Last updated: 05 June 2006
248  <br>  <br>
249  Copyright &copy; 1997-2005 University of Cambridge.  Copyright &copy; 1997-2006 University of Cambridge.
250  <p>  <p>
251  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
252  </p>  </p>

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