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News about PCRE releases |
News about PCRE releases |
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Release 7.0 23-Nov-06 |
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This release has a new major number because there have been some internal |
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upheavals to facilitate the addition of new optimizations and other facilities, |
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and to make subsequent maintenance and extension easier. Compilation is likely |
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to be a bit slower, but there should be no major effect on runtime performance. |
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Previously compiled patterns are NOT upwards compatible with this release. If |
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you have saved compiled patterns from a previous release, you will have to |
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re-compile them. Important changes that are visible to users are: |
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1. The Unicode property tables have been updated to Unicode 5.0.0, which adds |
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some more scripts. |
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2. The option PCRE_NEWLINE_ANY causes PCRE to recognize any Unicode newline |
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sequence as a newline. |
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3. The \R escape matches a single Unicode newline sequence as a single unit. |
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4. New features that will appear in Perl 5.10 are now in PCRE. These include |
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alternative Perl syntax for named parentheses, and Perl syntax for |
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recursion. |
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5. The C++ wrapper interface has been extended by the addition of a |
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QuoteMeta function and the ability to allow copy construction and |
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assignment. |
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For a complete list of changes, see the ChangeLog file. |
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Release 6.7 04-Jul-06 |
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The main additions to this release are the ability to use the same name for |
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multiple sets of parentheses, and support for CRLF line endings in both the |
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library and pcregrep (and in pcretest for testing). |
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Thanks to Ian Taylor, the stack usage for many kinds of pattern has been |
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significantly reduced for certain subject strings. |
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Release 6.5 01-Feb-06 |
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Important changes in this release: |
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1. A number of new features have been added to pcregrep. |
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2. The Unicode property tables have been updated to Unicode 4.1.0, and the |
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supported properties have been extended with script names such as "Arabic", |
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and the derived properties "Any" and "L&". This has necessitated a change to |
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the interal format of compiled patterns. Any saved compiled patterns that |
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use \p or \P must be recompiled. |
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3. The specification of recursion in patterns has been changed so that all |
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recursive subpatterns are automatically treated as atomic groups. Thus, for |
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example, (?R) is treated as if it were (?>(?R)). This is necessary because |
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otherwise there are situations where recursion does not work. |
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See the ChangeLog for a complete list of changes, which include a number of bug |
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fixes and tidies. |
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Release 6.0 07-Jun-05 |
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The release number has been increased to 6.0 because of the addition of several |
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major new pieces of functionality. |
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A new function, pcre_dfa_exec(), which implements pattern matching using a DFA |
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algorithm, has been added. This has a number of advantages for certain cases, |
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though it does run more slowly, and lacks the ability to capture substrings. On |
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the other hand, it does find all matches, not just the first, and it works |
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better for partial matching. The pcrematching man page discusses the |
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differences. |
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The pcretest program has been enhanced so that it can make use of the new |
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pcre_dfa_exec() matching function and the extra features it provides. |
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The distribution now includes a C++ wrapper library. This is built |
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automatically if a C++ compiler is found. The pcrecpp man page discusses this |
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interface. |
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The code itself has been re-organized into many more files, one for each |
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function, so it no longer requires everything to be linked in when static |
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linkage is used. As a consequence, some internal functions have had to have |
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their names exposed. These functions all have names starting with _pcre_. They |
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are undocumented, and are not intended for use by outside callers. |
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The pcregrep program has been enhanced with new functionality such as |
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multiline-matching and options for output more matching context. See the |
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ChangeLog for a complete list of changes to the library and the utility |
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programs. |
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Release 5.0 13-Sep-04 |
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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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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 |
Release 4.4 21-Aug-03 |
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