update to pcre 7.9

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@13706 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/pcre/doc/html/pcre.html

@@ -18,18 +18,26 @@ man page, in case the conversion went wrong.
 <li><a name="TOC3" href="#SEC3">LIMITATIONS</a>
 <li><a name="TOC4" href="#SEC4">UTF-8 AND UNICODE PROPERTY SUPPORT</a>
 <li><a name="TOC5" href="#SEC5">AUTHOR</a>
+<li><a name="TOC6" href="#SEC6">REVISION</a>
 </ul>
 <br><a name="SEC1" href="#TOC1">INTRODUCTION</a><br>
 <P>
 The PCRE library is a set of functions that implement regular expression
 pattern matching using the same syntax and semantics as Perl, with just a few
-differences. The current implementation of PCRE (release 6.x) corresponds
-approximately with Perl 5.8, including support for UTF-8 encoded strings and
-Unicode general category properties. However, this support has to be explicitly
-enabled; it is not the default.
+differences. Certain features that appeared in Python and PCRE before they
+appeared in Perl are also available using the Python syntax. There is also some
+support for certain .NET and Oniguruma syntax items, and there is an option for
+requesting some minor changes that give better JavaScript compatibility.
 </P>
 <P>
-In addition to the Perl-compatible matching function, PCRE also contains an
+The current implementation of PCRE (release 7.x) corresponds approximately with
+Perl 5.10, including support for UTF-8 encoded strings and Unicode general
+category properties. However, UTF-8 and Unicode support has to be explicitly
+enabled; it is not the default. The Unicode tables correspond to Unicode
+release 5.1.
+</P>
+<P>
+In addition to the Perl-compatible matching function, PCRE contains an
 alternative matching function that matches the same compiled patterns in a
 different way. In certain circumstances, the alternative function has some
 advantages. For a discussion of the two matching algorithms, see the
@@ -52,7 +60,9 @@ supported by PCRE are given in separate documents. See the
 <a href="pcrepattern.html"><b>pcrepattern</b></a>
 and
 <a href="pcrecompat.html"><b>pcrecompat</b></a>
-pages.
+pages. There is a syntax summary in the
+<a href="pcresyntax.html"><b>pcresyntax</b></a>
+page.
 </P>
 <P>
 Some features of PCRE can be included, excluded, or changed when the library is
@@ -82,6 +92,7 @@ all the sections are concatenated, for ease of searching. The sections are as
 follows:
 <pre>
   pcre              this document
+  pcre-config       show PCRE installation configuration information
   pcreapi           details of PCRE's native C API
   pcrebuild         options for building PCRE
   pcrecallout       details of the callout feature
@@ -91,6 +102,7 @@ follows:
   pcrematching      discussion of the two matching algorithms
   pcrepartial       details of the partial matching facility
   pcrepattern       syntax and semantics of supported regular expressions
+  pcresyntax        quick syntax reference
   pcreperform       discussion of performance issues
   pcreposix         the POSIX-compatible C API
   pcreprecompile    details of saving and re-using precompiled patterns
@@ -114,21 +126,18 @@ internal linkage size of 3 or 4 (see the <b>README</b> file in the source
 distribution and the
 <a href="pcrebuild.html"><b>pcrebuild</b></a>
 documentation for details). In these cases the limit is substantially larger.
-However, the speed of execution will be slower.
+However, the speed of execution is slower.
 </P>
 <P>
-All values in repeating quantifiers must be less than 65536. The maximum
-compiled length of subpattern with an explicit repeat count is 30000 bytes. The
-maximum number of capturing subpatterns is 65535.
+All values in repeating quantifiers must be less than 65536.
 </P>
 <P>
-There is no limit to the number of non-capturing subpatterns, but the maximum
-depth of nesting of all kinds of parenthesized subpattern, including capturing
-subpatterns, assertions, and other types of subpattern, is 200.
+There is no limit to the number of parenthesized subpatterns, but there can be
+no more than 65535 capturing subpatterns.
 </P>
 <P>
-The maximum length of name for a named subpattern is 32, and the maximum number
-of named subpatterns is 10000.
+The maximum length of name for a named subpattern is 32 characters, and the
+maximum number of named subpatterns is 10000.
 </P>
 <P>
 The maximum length of a subject string is the largest positive number that an
@@ -151,14 +160,15 @@ category properties was added.
 In order process UTF-8 strings, you must build PCRE to include UTF-8 support in
 the code, and, in addition, you must call
 <a href="pcre_compile.html"><b>pcre_compile()</b></a>
-with the PCRE_UTF8 option flag. When you do this, both the pattern and any
-subject strings that are matched against it are treated as UTF-8 strings
-instead of just strings of bytes.
+with the PCRE_UTF8 option flag, or the pattern must start with the sequence
+(*UTF8). When either of these is the case, both the pattern and any subject
+strings that are matched against it are treated as UTF-8 strings instead of
+just strings of bytes.
 </P>
 <P>
 If you compile PCRE with UTF-8 support, but do not use it at run time, the
 library will be a bit bigger, but the additional run time overhead is limited
-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.
 </P>
 <P>
 If PCRE is built with Unicode character property support (which implies UTF-8
@@ -172,56 +182,95 @@ documentation. Only the short names for properties are supported. For example,
 \p{L} matches a letter. Its Perl synonym, \p{Letter}, is not supported.
 Furthermore, in Perl, many properties may optionally be prefixed by "Is", for
 compatibility with Perl 5.6. PCRE does not support this.
+<a name="utf8strings"></a></P>
+<br><b>
+Validity of UTF-8 strings
+</b><br>
+<P>
+When you set the PCRE_UTF8 flag, the strings passed as patterns and subjects
+are (by default) checked for validity on entry to the relevant functions. From
+release 7.3 of PCRE, the check is according the rules of RFC 3629, which are
+themselves derived from the Unicode specification. Earlier releases of PCRE
+followed the rules of RFC 2279, which allows the full range of 31-bit values (0
+to 0x7FFFFFFF). The current check allows only values in the range U+0 to
+U+10FFFF, excluding U+D800 to U+DFFF.
 </P>
 <P>
-The following comments apply when PCRE is running in UTF-8 mode:
+The excluded code points are the "Low Surrogate Area" of Unicode, of which the
+Unicode Standard says this: "The Low Surrogate Area does not contain any
+character assignments, consequently no character code charts or namelists are
+provided for this area. Surrogates are reserved for use with UTF-16 and then
+must be used in pairs." The code points that are encoded by UTF-16 pairs are
+available as independent code points in the UTF-8 encoding. (In other words,
+the whole surrogate thing is a fudge for UTF-16 which unfortunately messes up
+UTF-8.)
 </P>
 <P>
-1. When you set the PCRE_UTF8 flag, the strings passed as patterns and subjects
-are checked for validity on entry to the relevant functions. If an invalid
-UTF-8 string is passed, an error return is given. 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. If you pass an invalid UTF-8 string to
-PCRE when PCRE_NO_UTF8_CHECK is set, the results are undefined. Your program
-may crash.
+If an invalid UTF-8 string is passed to PCRE, an error return
+(PCRE_ERROR_BADUTF8) is given. 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>
-2. An unbraced hexadecimal escape sequence (such as \xb3) matches a two-byte
+If you pass an invalid UTF-8 string when PCRE_NO_UTF8_CHECK is set, what
+happens depends on why the string is invalid. If the string conforms to the
+"old" definition of UTF-8 (RFC 2279), it is processed as a string of characters
+in the range 0 to 0x7FFFFFFF. In other words, apart from the initial validity
+test, PCRE (when in UTF-8 mode) handles strings according to the more liberal
+rules of RFC 2279. However, if the string does not even conform to RFC 2279,
+the result is undefined. Your program may crash.
+</P>
+<P>
+If you want to process strings of values in the full range 0 to 0x7FFFFFFF,
+encoded in a UTF-8-like manner as per the old RFC, you can set
+PCRE_NO_UTF8_CHECK to bypass the more restrictive test. However, in this
+situation, you will have to apply your own validity check.
+</P>
+<br><b>
+General comments about UTF-8 mode
+</b><br>
+<P>
+1. An unbraced hexadecimal escape sequence (such as \xb3) matches a two-byte
 UTF-8 character if the value is greater than 127.
 </P>
 <P>
-3. Octal numbers up to \777 are recognized, and match two-byte UTF-8
+2. Octal numbers up to \777 are recognized, and match two-byte UTF-8
 characters for values greater than \177.
 </P>
 <P>
-4. Repeat quantifiers apply to complete UTF-8 characters, not to individual
+3. Repeat quantifiers apply to complete UTF-8 characters, not to individual
 bytes, for example: \x{100}{3}.
 </P>
 <P>
-5. The dot metacharacter matches one UTF-8 character instead of a single byte.
+4. The dot metacharacter matches one UTF-8 character instead of a single byte.
 </P>
 <P>
-6. The escape sequence \C can be used to match a single byte in UTF-8 mode,
+5. The escape sequence \C can be used to match a single byte in UTF-8 mode,
 but its use can lead to some strange effects. This facility is not available in
 the alternative matching function, <b>pcre_dfa_exec()</b>.
 </P>
 <P>
-7. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
+6. The character escapes \b, \B, \d, \D, \s, \S, \w, and \W correctly
 test characters of any code value, but the characters that PCRE 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 includes Unicode
 property support, because to do otherwise would slow down PCRE in many common
 cases. If you really want to test for a wider sense of, say, "digit", you
-must use Unicode property tests such as \p{Nd}.
+must use Unicode property tests such as \p{Nd}. Note that this also applies to
+\b, because it is defined in terms of \w and \W.
 </P>
 <P>
-8. Similarly, characters that match the POSIX named character classes are all
+7. Similarly, characters that match the POSIX named character classes are all
 low-valued characters.
 </P>
 <P>
+8. However, the Perl 5.10 horizontal and vertical whitespace matching escapes
+(\h, \H, \v, and \V) do match all the appropriate Unicode characters.
+</P>
+<P>
 9. Case-insensitive matching applies only to characters whose values are less
 than 128, unless PCRE is built with Unicode property support. Even when Unicode
 property support is available, PCRE still uses its own character tables when
@@ -236,17 +285,22 @@ these are not supported by PCRE.
 <P>
 Philip Hazel
 <br>
-University Computing Service,
+University Computing Service
+<br>
+Cambridge CB2 3QH, England.
 <br>
-Cambridge CB2 3QG, England.
 </P>
 <P>
 Putting an actual email address here seems to have been a spam magnet, so I've
-taken it away. If you want to email me, use my initial and surname, separated
-by a dot, at the domain ucs.cam.ac.uk.
-Last updated: 05 June 2006
+taken it away. If you want to email me, use my two initials, followed by the
+two digits 10, at the domain cam.ac.uk.
+</P>
+<br><a name="SEC6" href="#TOC1">REVISION</a><br>
+<P>
+Last updated: 11 April 2009
+<br>
+Copyright &copy; 1997-2009 University of Cambridge.
 <br>
-Copyright &copy; 1997-2006 University of Cambridge.
 <p>
 Return to the <a href="index.html">PCRE index page</a>.
 </p>