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News about PCRE releases
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------------------------
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Release 5.0 13-Sep-04
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---------------------
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The licence under which PCRE is released has been changed to the more
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conventional "BSD" licence.
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In the code, some bugs have been fixed, and there are also some major changes
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in this release (which is why I've increased the number to 5.0). Some changes
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are internal rearrangements, and some provide a number of new facilities. The
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new features are:
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1. There's an "automatic callout" feature that inserts callouts before every
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item in the regex, and there's a new callout field that gives the position
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in the pattern - useful for debugging and tracing.
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2. The extra_data structure can now be used to pass in a set of character
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tables at exec time. This is useful if compiled regex are saved and re-used
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at a later time when the tables may not be at the same address. If the
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default internal tables are used, the pointer saved with the compiled
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pattern is now set to NULL, which means that you don't need to do anything
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special unless you are using custom tables.
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3. It is possible, with some restrictions on the content of the regex, to
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request "partial" matching. A special return code is given if all of the
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subject string matched part of the regex. This could be useful for testing
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an input field as it is being typed.
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4. There is now some optional support for Unicode character properties, which
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means that the patterns items such as \p{Lu} and \X can now be used. Only
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the general category properties are supported. If PCRE is compiled with this
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support, an additional 90K data structure is include, which increases the
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size of the library dramatically.
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5. There is support for saving compiled patterns and re-using them later.
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6. There is support for running regular expressions that were compiled on a
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different host with the opposite endianness.
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7. The pcretest program has been extended to accommodate the new features.
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The main internal rearrangement is that sequences of literal characters are no
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longer handled as strings. Instead, each character is handled on its own. This
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makes some UTF-8 handling easier, and makes the support of partial matching
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possible. Compiled patterns containing long literal strings will be larger as a
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result of this change; I hope that performance will not be much affected.
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Release 4.5 01-Dec-03
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---------------------
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Again mainly a bug-fix and tidying release, with only a couple of new features:
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1. It's possible now to compile PCRE so that it does not use recursive
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function calls when matching. Instead it gets memory from the heap. This slows
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things down, but may be necessary on systems with limited stacks.
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2. UTF-8 string checking has been tightened to reject overlong sequences and to
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check that a starting offset points to the start of a character. Failure of the
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latter returns a new error code: PCRE_ERROR_BADUTF8_OFFSET.
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3. PCRE can now be compiled for systems that use EBCDIC code.
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Release 4.4 21-Aug-03
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---------------------
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This is mainly a bug-fix and tidying release. The only new feature is that PCRE
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checks UTF-8 strings for validity by default. There is an option to suppress
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this, just in case anybody wants that teeny extra bit of performance.
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Releases 4.1 - 4.3
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------------------
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Sorry, I forgot about updating the NEWS file for these releases. Please take a
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look at ChangeLog.
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Release 4.0 17-Feb-03
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---------------------
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There have been a lot of changes for the 4.0 release, adding additional
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functionality and mending bugs. Below is a list of the highlights of the new
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functionality. For full details of these features, please consult the
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documentation. For a complete list of changes, see the ChangeLog file.
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1. Support for Perl's \Q...\E escapes.
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2. "Possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java
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package. They provide some syntactic sugar for simple cases of "atomic
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grouping".
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3. Support for the \G assertion. It is true when the current matching position
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is at the start point of the match.
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4. A new feature that provides some of the functionality that Perl provides
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with (?{...}). The facility is termed a "callout". The way it is done in PCRE
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is for the caller to provide an optional function, by setting pcre_callout to
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its entry point. To get the function called, the regex must include (?C) at
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appropriate points.
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5. Support for recursive calls to individual subpatterns. This makes it really
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easy to get totally confused.
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6. Support for named subpatterns. The Python syntax (?P<name>...) is used to
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name a group.
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7. Several extensions to UTF-8 support; it is now fairly complete. There is an
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option for pcregrep to make it operate in UTF-8 mode.
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8. The single man page has been split into a number of separate man pages.
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These also give rise to individual HTML pages which are put in a separate
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directory. There is an index.html page that lists them all. Some hyperlinking
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between the pages has been installed.
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Release 3.5 15-Aug-01
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---------------------
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1. The configuring system has been upgraded to use later versions of autoconf
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and libtool. By default it builds both a shared and a static library if the OS
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supports it. You can use --disable-shared or --disable-static on the configure
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command if you want only one of them.
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2. The pcretest utility is now installed along with pcregrep because it is
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useful for users (to test regexs) and by doing this, it automatically gets
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relinked by libtool. The documentation has been turned into a man page, so
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there are now .1, .txt, and .html versions in /doc.
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3. Upgrades to pcregrep:
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(i) Added long-form option names like gnu grep.
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(ii) Added --help to list all options with an explanatory phrase.
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(iii) Added -r, --recursive to recurse into sub-directories.
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(iv) Added -f, --file to read patterns from a file.
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4. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
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script, to force use of CR or LF instead of \n in the source. On non-Unix
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systems, the value can be set in config.h.
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5. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
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absolute limit. Changed the text of the error message to make this clear, and
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likewise updated the man page.
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6. The limit of 99 on the number of capturing subpatterns has been removed.
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The new limit is 65535, which I hope will not be a "real" limit.
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Release 3.3 01-Aug-00
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---------------------
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There is some support for UTF-8 character strings. This is incomplete and
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experimental. The documentation describes what is and what is not implemented.
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Otherwise, this is just a bug-fixing release.
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Release 3.0 01-Feb-00
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---------------------
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1. A "configure" script is now used to configure PCRE for Unix systems. It
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builds a Makefile, a config.h file, and the pcre-config script.
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2. PCRE is built as a shared library by default.
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3. There is support for POSIX classes such as [:alpha:].
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5. There is an experimental recursion feature.
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----------------------------------------------------------------------------
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IMPORTANT FOR THOSE UPGRADING FROM VERSIONS BEFORE 2.00
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Please note that there has been a change in the API such that a larger
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ovector is required at matching time, to provide some additional workspace.
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The new man page has details. This change was necessary in order to support
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some of the new functionality in Perl 5.005.
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IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.00
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Another (I hope this is the last!) change has been made to the API for the
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pcre_compile() function. An additional argument has been added to make it
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possible to pass over a pointer to character tables built in the current
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locale by pcre_maketables(). To use the default tables, this new arguement
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should be passed as NULL.
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IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05
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Yet another (and again I hope this really is the last) change has been made
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to the API for the pcre_exec() function. An additional argument has been
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added to make it possible to start the match other than at the start of the
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subject string. This is important if there are lookbehinds. The new man
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page has the details, but you just want to convert existing programs, all
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you need to do is to stick in a new fifth argument to pcre_exec(), with a
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value of zero. For example, change
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pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)
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to
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pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)
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****
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