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Thu Sep 20 10:19:16 2007 UTC (8 years, 2 months ago) by ph10
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Documentation tidies and clarifications.
1 News about PCRE releases
2 ------------------------
5 Release 7.4 21-Sep-07
6 ---------------------
8 The only change of specification is the addition of options to control whether
9 \R matches any Unicode line ending (the default) or just CR, LF, and CRLF.
10 Otherwise, the changes are bug fixes and a refactoring to reduce the number of
11 relocations needed in a shared library.
14 Release 7.3 28-Aug-07
15 ---------------------
17 Most changes are bug fixes. Some that are not:
19 1. There is some support for Perl 5.10's experimental "backtracking control
20 verbs" such as (*PRUNE).
22 2. UTF-8 checking is now as per RFC 3629 instead of RFC 2279; this is more
23 restrictive in the strings it accepts.
25 3. Checking for potential integer overflow has been made more dynamic, and as a
26 consequence there is no longer a hard limit on the size of a subpattern that
27 has a limited repeat count.
29 4. When CRLF is a valid line-ending sequence, pcre_exec() and pcre_dfa_exec()
30 no longer advance by two characters instead of one when an unanchored match
31 fails at CRLF if there are explicit CR or LF matches within the pattern.
32 This gets rid of some anomalous effects that previously occurred.
34 5. Some PCRE-specific settings for varying the newline options at the start of
35 a pattern have been added.
38 Release 7.2 19-Jun-07
39 ---------------------
41 WARNING: saved patterns that were compiled by earlier versions of PCRE must be
42 recompiled for use with 7.2 (necessitated by the addition of \K, \h, \H, \v,
43 and \V).
45 Correction to the notes for 7.1: the note about shared libraries for Windows is
46 wrong. Previously, three libraries were built, but each could function
47 independently. For example, the pcreposix library also included all the
48 functions from the basic pcre library. The change is that the three libraries
49 are no longer independent. They are like the Unix libraries. To use the
50 pcreposix functions, for example, you need to link with both the pcreposix and
51 the basic pcre library.
53 Some more features from Perl 5.10 have been added:
55 (?-n) and (?+n) relative references for recursion and subroutines.
57 (?(-n) and (?(+n) relative references as conditions.
59 \k{name} and \g{name} are synonyms for \k<name>.
61 \K to reset the start of the matched string; for example, (foo)\Kbar
62 matches bar preceded by foo, but only sets bar as the matched string.
64 (?| introduces a group where the capturing parentheses in each alternative
65 start from the same number; for example, (?|(abc)|(xyz)) sets capturing
66 parentheses number 1 in both cases.
68 \h, \H, \v, \V match horizontal and vertical whitespace, respectively.
71 Release 7.1 24-Apr-07
72 ---------------------
74 There is only one new feature in this release: a linebreak setting of
75 PCRE_NEWLINE_ANYCRLF. It is a cut-down version of PCRE_NEWLINE_ANY, which
76 recognizes only CRLF, CR, and LF as linebreaks.
78 A few bugs are fixed (see ChangeLog for details), but the major change is a
79 complete re-implementation of the build system. This now has full Autotools
80 support and so is now "standard" in some sense. It should help with compiling
81 PCRE in a wide variety of environments.
83 NOTE: when building shared libraries for Windows, three dlls are now built,
84 called libpcre, libpcreposix, and libpcrecpp. Previously, everything was
85 included in a single dll.
87 Another important change is that the dftables auxiliary program is no longer
88 compiled and run at "make" time by default. Instead, a default set of character
89 tables (assuming ASCII coding) is used. If you want to use dftables to generate
90 the character tables as previously, add --enable-rebuild-chartables to the
91 "configure" command. You must do this if you are compiling PCRE to run on a
92 system that uses EBCDIC code.
94 There is a discussion about character tables in the README file. The default is
95 not to use dftables so that that there is no problem when cross-compiling.
98 Release 7.0 19-Dec-06
99 ---------------------
101 This release has a new major number because there have been some internal
102 upheavals to facilitate the addition of new optimizations and other facilities,
103 and to make subsequent maintenance and extension easier. Compilation is likely
104 to be a bit slower, but there should be no major effect on runtime performance.
105 Previously compiled patterns are NOT upwards compatible with this release. If
106 you have saved compiled patterns from a previous release, you will have to
107 re-compile them. Important changes that are visible to users are:
109 1. The Unicode property tables have been updated to Unicode 5.0.0, which adds
110 some more scripts.
112 2. The option PCRE_NEWLINE_ANY causes PCRE to recognize any Unicode newline
113 sequence as a newline.
115 3. The \R escape matches a single Unicode newline sequence as a single unit.
117 4. New features that will appear in Perl 5.10 are now in PCRE. These include
118 alternative Perl syntax for named parentheses, and Perl syntax for
119 recursion.
121 5. The C++ wrapper interface has been extended by the addition of a
122 QuoteMeta function and the ability to allow copy construction and
123 assignment.
125 For a complete list of changes, see the ChangeLog file.
128 Release 6.7 04-Jul-06
129 ---------------------
131 The main additions to this release are the ability to use the same name for
132 multiple sets of parentheses, and support for CRLF line endings in both the
133 library and pcregrep (and in pcretest for testing).
135 Thanks to Ian Taylor, the stack usage for many kinds of pattern has been
136 significantly reduced for certain subject strings.
139 Release 6.5 01-Feb-06
140 ---------------------
142 Important changes in this release:
144 1. A number of new features have been added to pcregrep.
146 2. The Unicode property tables have been updated to Unicode 4.1.0, and the
147 supported properties have been extended with script names such as "Arabic",
148 and the derived properties "Any" and "L&". This has necessitated a change to
149 the interal format of compiled patterns. Any saved compiled patterns that
150 use \p or \P must be recompiled.
152 3. The specification of recursion in patterns has been changed so that all
153 recursive subpatterns are automatically treated as atomic groups. Thus, for
154 example, (?R) is treated as if it were (?>(?R)). This is necessary because
155 otherwise there are situations where recursion does not work.
157 See the ChangeLog for a complete list of changes, which include a number of bug
158 fixes and tidies.
161 Release 6.0 07-Jun-05
162 ---------------------
164 The release number has been increased to 6.0 because of the addition of several
165 major new pieces of functionality.
167 A new function, pcre_dfa_exec(), which implements pattern matching using a DFA
168 algorithm, has been added. This has a number of advantages for certain cases,
169 though it does run more slowly, and lacks the ability to capture substrings. On
170 the other hand, it does find all matches, not just the first, and it works
171 better for partial matching. The pcrematching man page discusses the
172 differences.
174 The pcretest program has been enhanced so that it can make use of the new
175 pcre_dfa_exec() matching function and the extra features it provides.
177 The distribution now includes a C++ wrapper library. This is built
178 automatically if a C++ compiler is found. The pcrecpp man page discusses this
179 interface.
181 The code itself has been re-organized into many more files, one for each
182 function, so it no longer requires everything to be linked in when static
183 linkage is used. As a consequence, some internal functions have had to have
184 their names exposed. These functions all have names starting with _pcre_. They
185 are undocumented, and are not intended for use by outside callers.
187 The pcregrep program has been enhanced with new functionality such as
188 multiline-matching and options for output more matching context. See the
189 ChangeLog for a complete list of changes to the library and the utility
190 programs.
193 Release 5.0 13-Sep-04
194 ---------------------
196 The licence under which PCRE is released has been changed to the more
197 conventional "BSD" licence.
199 In the code, some bugs have been fixed, and there are also some major changes
200 in this release (which is why I've increased the number to 5.0). Some changes
201 are internal rearrangements, and some provide a number of new facilities. The
202 new features are:
204 1. There's an "automatic callout" feature that inserts callouts before every
205 item in the regex, and there's a new callout field that gives the position
206 in the pattern - useful for debugging and tracing.
208 2. The extra_data structure can now be used to pass in a set of character
209 tables at exec time. This is useful if compiled regex are saved and re-used
210 at a later time when the tables may not be at the same address. If the
211 default internal tables are used, the pointer saved with the compiled
212 pattern is now set to NULL, which means that you don't need to do anything
213 special unless you are using custom tables.
215 3. It is possible, with some restrictions on the content of the regex, to
216 request "partial" matching. A special return code is given if all of the
217 subject string matched part of the regex. This could be useful for testing
218 an input field as it is being typed.
220 4. There is now some optional support for Unicode character properties, which
221 means that the patterns items such as \p{Lu} and \X can now be used. Only
222 the general category properties are supported. If PCRE is compiled with this
223 support, an additional 90K data structure is include, which increases the
224 size of the library dramatically.
226 5. There is support for saving compiled patterns and re-using them later.
228 6. There is support for running regular expressions that were compiled on a
229 different host with the opposite endianness.
231 7. The pcretest program has been extended to accommodate the new features.
233 The main internal rearrangement is that sequences of literal characters are no
234 longer handled as strings. Instead, each character is handled on its own. This
235 makes some UTF-8 handling easier, and makes the support of partial matching
236 possible. Compiled patterns containing long literal strings will be larger as a
237 result of this change; I hope that performance will not be much affected.
240 Release 4.5 01-Dec-03
241 ---------------------
243 Again mainly a bug-fix and tidying release, with only a couple of new features:
245 1. It's possible now to compile PCRE so that it does not use recursive
246 function calls when matching. Instead it gets memory from the heap. This slows
247 things down, but may be necessary on systems with limited stacks.
249 2. UTF-8 string checking has been tightened to reject overlong sequences and to
250 check that a starting offset points to the start of a character. Failure of the
251 latter returns a new error code: PCRE_ERROR_BADUTF8_OFFSET.
253 3. PCRE can now be compiled for systems that use EBCDIC code.
256 Release 4.4 21-Aug-03
257 ---------------------
259 This is mainly a bug-fix and tidying release. The only new feature is that PCRE
260 checks UTF-8 strings for validity by default. There is an option to suppress
261 this, just in case anybody wants that teeny extra bit of performance.
264 Releases 4.1 - 4.3
265 ------------------
267 Sorry, I forgot about updating the NEWS file for these releases. Please take a
268 look at ChangeLog.
271 Release 4.0 17-Feb-03
272 ---------------------
274 There have been a lot of changes for the 4.0 release, adding additional
275 functionality and mending bugs. Below is a list of the highlights of the new
276 functionality. For full details of these features, please consult the
277 documentation. For a complete list of changes, see the ChangeLog file.
279 1. Support for Perl's \Q...\E escapes.
281 2. "Possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java
282 package. They provide some syntactic sugar for simple cases of "atomic
283 grouping".
285 3. Support for the \G assertion. It is true when the current matching position
286 is at the start point of the match.
288 4. A new feature that provides some of the functionality that Perl provides
289 with (?{...}). The facility is termed a "callout". The way it is done in PCRE
290 is for the caller to provide an optional function, by setting pcre_callout to
291 its entry point. To get the function called, the regex must include (?C) at
292 appropriate points.
294 5. Support for recursive calls to individual subpatterns. This makes it really
295 easy to get totally confused.
297 6. Support for named subpatterns. The Python syntax (?P<name>...) is used to
298 name a group.
300 7. Several extensions to UTF-8 support; it is now fairly complete. There is an
301 option for pcregrep to make it operate in UTF-8 mode.
303 8. The single man page has been split into a number of separate man pages.
304 These also give rise to individual HTML pages which are put in a separate
305 directory. There is an index.html page that lists them all. Some hyperlinking
306 between the pages has been installed.
309 Release 3.5 15-Aug-01
310 ---------------------
312 1. The configuring system has been upgraded to use later versions of autoconf
313 and libtool. By default it builds both a shared and a static library if the OS
314 supports it. You can use --disable-shared or --disable-static on the configure
315 command if you want only one of them.
317 2. The pcretest utility is now installed along with pcregrep because it is
318 useful for users (to test regexs) and by doing this, it automatically gets
319 relinked by libtool. The documentation has been turned into a man page, so
320 there are now .1, .txt, and .html versions in /doc.
322 3. Upgrades to pcregrep:
323 (i) Added long-form option names like gnu grep.
324 (ii) Added --help to list all options with an explanatory phrase.
325 (iii) Added -r, --recursive to recurse into sub-directories.
326 (iv) Added -f, --file to read patterns from a file.
328 4. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
329 script, to force use of CR or LF instead of \n in the source. On non-Unix
330 systems, the value can be set in config.h.
332 5. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
333 absolute limit. Changed the text of the error message to make this clear, and
334 likewise updated the man page.
336 6. The limit of 99 on the number of capturing subpatterns has been removed.
337 The new limit is 65535, which I hope will not be a "real" limit.
340 Release 3.3 01-Aug-00
341 ---------------------
343 There is some support for UTF-8 character strings. This is incomplete and
344 experimental. The documentation describes what is and what is not implemented.
345 Otherwise, this is just a bug-fixing release.
348 Release 3.0 01-Feb-00
349 ---------------------
351 1. A "configure" script is now used to configure PCRE for Unix systems. It
352 builds a Makefile, a config.h file, and the pcre-config script.
354 2. PCRE is built as a shared library by default.
356 3. There is support for POSIX classes such as [:alpha:].
358 5. There is an experimental recursion feature.
360 ----------------------------------------------------------------------------
363 Please note that there has been a change in the API such that a larger
364 ovector is required at matching time, to provide some additional workspace.
365 The new man page has details. This change was necessary in order to support
366 some of the new functionality in Perl 5.005.
370 Another (I hope this is the last!) change has been made to the API for the
371 pcre_compile() function. An additional argument has been added to make it
372 possible to pass over a pointer to character tables built in the current
373 locale by pcre_maketables(). To use the default tables, this new arguement
374 should be passed as NULL.
378 Yet another (and again I hope this really is the last) change has been made
379 to the API for the pcre_exec() function. An additional argument has been
380 added to make it possible to start the match other than at the start of the
381 subject string. This is important if there are lookbehinds. The new man
382 page has the details, but you just want to convert existing programs, all
383 you need to do is to stick in a new fifth argument to pcre_exec(), with a
384 value of zero. For example, change
386 pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)
387 to
388 pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)
390 ****


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