--- code/trunk/doc/html/pcre.html 2007/02/24 21:41:06 83 +++ code/trunk/doc/html/pcre.html 2007/02/24 21:41:21 87 @@ -156,10 +156,13 @@ support), the escape sequences \p{..}, \P{..}, and \X are supported. The available properties that can be tested are limited to the general category properties such as Lu for an upper case letter or Nd for a decimal -number. A full list is given in the +number, the Unicode script names such as Arabic or Han, and the derived +properties Any and L&. A full list is given in the pcrepattern -documentation. The PCRE library is increased in size by about 90K when Unicode -property support is included. +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.

The following comments apply when PCRE is running in UTF-8 mode: @@ -177,31 +180,23 @@ may crash.

-2. In a pattern, the escape sequence \x{...}, where the contents of the braces -is a string of hexadecimal digits, is interpreted as a UTF-8 character whose -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. +2. An unbraced hexadecimal escape sequence (such as \xb3) matches a two-byte +UTF-8 character if the value is greater than 127.

-3. The original hexadecimal escape sequence, \xhh, matches a two-byte UTF-8 -character if the value is greater than 127. -

-

-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}.

-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.

-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, pcre_dfa_exec().

-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 @@ -210,16 +205,19 @@ must use Unicode property tests such as \p{Nd}.

-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.

-9. Case-insensitive matching applies only to characters whose values are less +8. 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 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. +values. Even when Unicode property support is available, PCRE supports +case-insensitive matching only when there is a one-to-one mapping between a +letter's cases. There are a small number of many-to-one mappings in Unicode; +these are not supported by PCRE.


AUTHOR

@@ -233,9 +231,9 @@ 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: 07 March 2005 +Last updated: 24 January 2006
-Copyright © 1997-2005 University of Cambridge. +Copyright © 1997-2006 University of Cambridge.

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