--- code/trunk/doc/html/pcre.html 2007/02/24 21:41:06 83 +++ code/trunk/doc/html/pcre.html 2007/02/24 21:41:34 91 @@ -95,6 +95,7 @@ pcreposix the POSIX-compatible C API pcreprecompile details of saving and re-using precompiled patterns pcresample discussion of the sample program + pcrestack discussion of stack usage pcretest description of the pcretest testing command In addition, in the "man" and HTML formats, there is a short page for each @@ -116,8 +117,9 @@ However, the speed of execution will be slower.

-All values in repeating quantifiers must be less than 65536. -The maximum number of capturing subpatterns is 65535. +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.

There is no limit to the number of non-capturing subpatterns, but the maximum @@ -125,11 +127,18 @@ subpatterns, assertions, and other types of subpattern, is 200.

+The maximum length of name for a named subpattern is 32, and the maximum number +of named subpatterns is 10000. +


The maximum length of a subject string is the largest positive number that an integer variable can hold. However, when using the traditional matching function, PCRE uses recursion to handle subpatterns and indefinite repetition. This means that the available stack space may limit the size of a subject -string that can be processed by certain patterns. +string that can be processed by certain patterns. For a discussion of stack +issues, see the +pcrestack +documentation.


@@ -156,10 +165,13 @@ 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: @@ -177,16 +189,12 @@ 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. +3. Octal numbers up to \777 are recognized, and match two-byte UTF-8 +characters for values greater than \177.

4. Repeat quantifiers apply to complete UTF-8 characters, not to individual @@ -219,7 +227,10 @@ 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.


@@ -233,9 +244,9 @@ 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: 05 June 2006
-Copyright © 1997-2005 University of Cambridge. +Copyright © 1997-2006 University of Cambridge.

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