/[pcre]/code/trunk/doc/html/pcre.html

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-revision 535 by ph10,
Thu Jun  3 19:18:24 2010 UTC
+revision 654 by ph10,
Tue Aug  2 11:00:40 2011 UTC
 Line 30 
 support for one or two .NET and Onigurum
  for requesting some minor changes that give better JavaScript compatibility.
  </P>
  <P>
- The current implementation of PCRE corresponds approximately with Perl
+ The current implementation of PCRE corresponds approximately with Perl 5.12,
-.10/5.11, including support for UTF-8 encoded strings and Unicode general
+ including support for UTF-8 encoded strings and Unicode general category
- category properties. However, UTF-8 and Unicode support has to be explicitly
+ properties. However, UTF-8 and Unicode support has to be explicitly enabled; it
- enabled; it is not the default. The Unicode tables correspond to Unicode
+ is not the default. The Unicode tables correspond to Unicode release 6.0.0.
- release 5.2.0.
  </P>
  <P>
  In addition to the Perl-compatible matching function, PCRE contains an
-Line 208 
 the whole surrogate thing is a fudge for
+Line 207 
 the whole surrogate thing is a fudge for
  UTF-8.)
  </P>
  <P>
- If an invalid UTF-8 string is passed to PCRE, an error return
+ If an invalid UTF-8 string is passed to PCRE, an error return is given. At
- (PCRE_ERROR_BADUTF8) is given. In some situations, you may already know that
+ compile time, the only additional information is the offset to the first byte
- your strings are valid, and therefore want to skip these checks in order to
+ of the failing character. The runtime functions (<b>pcre_exec()</b> and
- improve performance. If you set the PCRE_NO_UTF8_CHECK flag at compile time or
+ <b>pcre_dfa_exec()</b>), pass back this information as well as a more detailed
- at run time, PCRE assumes that the pattern or subject it is given
+ reason code if the caller has provided memory in which to do this.
- (respectively) contains only valid UTF-8 codes. In this case, it does not
+ </P>
- diagnose an invalid UTF-8 string.
+ <P>
+ In some situations, you may already know that your strings are valid, and
+ therefore want to skip these checks in order to improve performance. If you set
+ the PCRE_NO_UTF8_CHECK flag at compile time or at run time, PCRE assumes that
+ the pattern or subject it is given (respectively) contains only valid UTF-8
+ codes. In this case, it does not diagnose an invalid UTF-8 string.
  </P>
  <P>
  If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, what
-Line 260 
 test characters of any code value, but,
+Line 264 
 test characters of any code value, but,
  recognizes as digits, spaces, or word characters remain the same set as before,
  all with values less than 256. This remains true even when PCRE is built to
  include Unicode property support, because to do otherwise would slow down PCRE
- in many common cases. Note that this also applies to \b, because it is defined
+ in many common cases. Note in particular that this applies to \b and \B,
- in terms of \w and \W. If you really want to test for a wider sense of, say,
+ because they are defined in terms of \w and \W. If you really want to test
- "digit", you can use explicit Unicode property tests such as \p{Nd}.
+ for a wider sense of, say, "digit", you can use explicit Unicode property tests
- Alternatively, if you set the PCRE_UCP option, the way that the character
+ such as \p{Nd}. Alternatively, if you set the PCRE_UCP option, the way that
- escapes work is changed so that Unicode properties are used to determine which
+ the character escapes work is changed so that Unicode properties are used to
- characters match. There are more details in the section on
+ determine which characters match. There are more details in the section on
  <a href="pcrepattern.html#genericchartypes">generic character types</a>
  in the
  <a href="pcrepattern.html"><b>pcrepattern</b></a>
-Line 276 
 documentation.
+Line 280 
 documentation.
  low-valued characters, unless the PCRE_UCP option is set.
  </P>
  <P>
-. However, the Perl 5.10 horizontal and vertical whitespace matching escapes
+. However, the horizontal and vertical whitespace matching escapes (\h, \H,
- (\h, \H, \v, and \V) do match all the appropriate Unicode characters,
+ \v, and \V) do match all the appropriate Unicode characters, whether or not
- whether or not PCRE_UCP is set.
+ PCRE_UCP is set.
  </P>
  <P>
 . Case-insensitive matching applies only to characters whose values are less
-Line 286 
 than 128, unless PCRE is built with Unic
+Line 290 
 than 128, unless PCRE is built with Unic
  property support is available, PCRE still uses its own character tables when
  checking the case of low-valued characters, so as not to degrade performance.
  The Unicode property information is used only for characters with higher
- values. Even when Unicode property support is available, PCRE supports
+ values. Furthermore, PCRE supports case-insensitive matching only when there is
- case-insensitive matching only when there is a one-to-one mapping between a
+ a one-to-one mapping between a letter's cases. There are a small number of
- letter's cases. There are a small number of many-to-one mappings in Unicode;
+ many-to-one mappings in Unicode; these are not supported by PCRE.
- these are not supported by PCRE.
  </P>
  <br><a name="SEC5" href="#TOC1">AUTHOR</a><br>
  <P>
-Line 307 
 two digits 10, at the domain cam.ac.uk.
+Line 310 
 two digits 10, at the domain cam.ac.uk.
  </P>
  <br><a name="SEC6" href="#TOC1">REVISION</a><br>
  <P>
- Last updated: 12 May 2010
+ Last updated: 07 May 2011
  <br>
- Copyright &copy; 1997-2010 University of Cambridge.
+ Copyright &copy; 1997-2011 University of Cambridge.
  <br>
  <p>
  Return to the <a href="index.html">PCRE index page</a>.

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