pcre specification

From 582b500cd996c96054615870fd13d6ab0ea77428 Mon Sep 17 00:00:00 2001 From: Jay Berkenbilt Date: Sat, 10 Oct 2009 15:10:05 +0000 Subject: start integrating windows port git-svn-id: svn+q:///qpdf/trunk@757 71b93d88-0707-0410-a8cf-f5a4172ac649 --- external-libs/pcre/doc/html/pcre.html | 190 ++++++++++++++++++++++++++++++++++ 1 file changed, 190 insertions(+) create mode 100644 external-libs/pcre/doc/html/pcre.html (limited to 'external-libs/pcre/doc/html/pcre.html') diff --git a/external-libs/pcre/doc/html/pcre.html b/external-libs/pcre/doc/html/pcre.html new file mode 100644 index 00000000..bb0d3548 --- /dev/null +++ b/external-libs/pcre/doc/html/pcre.html @@ -0,0 +1,190 @@ + + +pcre specification + + +This HTML document has been generated automatically from the original man page. +If there is any nonsense in it, please consult the man page, in case the +conversion went wrong.
+

DESCRIPTION +
USER DOCUMENTATION +
LIMITATIONS +
UTF-8 SUPPORT +
AUTHOR +

+
DESCRIPTION
+

+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 4.x) corresponds +approximately with Perl 5.8, including support for UTF-8 encoded strings. +However, this support has to be explicitly enabled; it is not the default. +

+PCRE is written in C and released as a C library. However, a number of people +have written wrappers and interfaces of various kinds. A C++ class is included +in these contributions, which can be found in the Contrib directory at +the primary FTP site, which is: +

+ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre +

+Details of exactly which Perl regular expression features are and are not +supported by PCRE are given in separate documents. See the +pcrepattern +and +pcrecompat +pages. +

+Some features of PCRE can be included, excluded, or changed when the library is +built. The +pcre_config() +function makes it possible for a client to discover which features are +available. Documentation about building PCRE for various operating systems can +be found in the README file in the source distribution. +

+
USER DOCUMENTATION
+

+The user documentation for PCRE has been split up into a number of different +sections. In the "man" format, each of these is a separate "man page". In the +HTML format, each is a separate page, linked from the index page. In the plain +text format, all the sections are concatenated, for ease of searching. The +sections are as follows: +

+  pcre              this document
+  pcreapi           details of PCRE's native API
+  pcrebuild         options for building PCRE
+  pcrecallout       details of the callout feature
+  pcrecompat        discussion of Perl compatibility
+  pcregrep          description of the pcregrep command
+  pcrepattern       syntax and semantics of supported
+                      regular expressions
+  pcreperform       discussion of performance issues
+  pcreposix         the POSIX-compatible API
+  pcresample        discussion of the sample program
+  pcretest          the pcretest testing command
+

+In addition, in the "man" and HTML formats, there is a short page for each +library function, listing its arguments and results. +

+
LIMITATIONS
+

+There are some size limitations in PCRE but it is hoped that they will never in +practice be relevant. +

+The maximum length of a compiled pattern is 65539 (sic) bytes if PCRE is +compiled with the default internal linkage size of 2. If you want to process +regular expressions that are truly enormous, you can compile PCRE with an +internal linkage size of 3 or 4 (see the README file in the source +distribution and the +pcrebuild +documentation for details). If these cases the limit is substantially larger. +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. +

+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. +

+The maximum length of a subject string is the largest positive number that an +integer variable can hold. However, 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. +

+
UTF-8 SUPPORT
+

+Starting at release 3.3, PCRE has had some support for character strings +encoded in the UTF-8 format. For release 4.0 this has been greatly extended to +cover most common requirements. +

+In order process UTF-8 strings, you must build PCRE to include UTF-8 support in +the code, and, in addition, you must call +pcre_compile() +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. +

+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. +

+The following comments apply when PCRE is running in UTF-8 mode: +

+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. +

+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. +

+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 +bytes, for example: \x{100}{3}. +

+5. 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, +but its use can lead to some strange effects. +

+7. 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. +

+8. Case-insensitive matching applies only to characters whose values are less +than 256. PCRE does not support the notion of "case" for higher-valued +characters. +

+9. PCRE does not support the use of Unicode tables and properties or the Perl +escapes \p, \P, and \X. +

+
AUTHOR
+

+Philip Hazel <ph10@cam.ac.uk> +
+University Computing Service, +
+Cambridge CB2 3QG, England. +
+Phone: +44 1223 334714 +