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Revision 175 - (hide annotations) (download)
Mon Jun 11 13:38:38 2007 UTC (7 years, 6 months ago) by ph10
File size: 14906 byte(s)
Added the Perl 5.10 (?| "branch reset" feature.

1 nigel 41 News about PCRE releases
2     ------------------------
3    
4 ph10 122
5 ph10 157 Release 7.2 30-Apr-07
6     ---------------------
7    
8 ph10 172 WARNING: saved patterns that were compiled by earlier versions of PCRE must be
9 ph10 168 recompiled for use with 7.2 (necessitated by the addition of \K).
10    
11 ph10 159 Correction to the notes for 7.1: the note about shared libraries for Windows is
12     wrong. Previously, three libraries were built, but each could function
13     independently. For example, the pcreposix library also included all the
14     functions from the basic pcre library. The change is that the three libraries
15     are no longer independent. They are like the Unix libraries. To use the
16     pcreposix functions, for example, you need to link with both the pcreposix and
17 ph10 157 the basic pcre library.
18    
19 ph10 166 Some more features from Perl 5.10 have been added:
20 ph10 157
21 ph10 166 (?-n) and (?+n) relative references for recursion and subroutines.
22 ph10 172
23 ph10 167 (Not sure if this one is actually in Perl 5.10)
24 ph10 172 (?(-n) and (?(+n) relative references as conditions.
25    
26 ph10 168 \K to reset the start of the matched string; for example, (foo)\Kbar
27 ph10 175 matches bar preceded by foo, but only sets bar as the matched string.
28    
29     (?| introduces a group where the capturing parentheses in each alternative
30     start from the same number; for example, (?|(abc)|(xyz)) sets capturing
31     parentheses number 1 in both cases.
32 ph10 166
33    
34 ph10 155 Release 7.1 24-Apr-07
35 nigel 93 ---------------------
36    
37 ph10 155 There is only one new feature in this release: a linebreak setting of
38     PCRE_NEWLINE_ANYCRLF. It is a cut-down version of PCRE_NEWLINE_ANY, which
39     recognizes only CRLF, CR, and LF as linebreaks.
40 ph10 122
41 ph10 155 A few bugs are fixed (see ChangeLog for details), but the major change is a
42     complete re-implementation of the build system. This now has full Autotools
43     support and so is now "standard" in some sense. It should help with compiling
44     PCRE in a wide variety of environments.
45    
46 ph10 146 NOTE: when building shared libraries for Windows, three dlls are now built,
47     called libpcre, libpcreposix, and libpcrecpp. Previously, everything was
48     included in a single dll.
49    
50     Another important change is that the dftables auxiliary program is no longer
51 ph10 128 compiled and run at "make" time by default. Instead, a default set of character
52     tables (assuming ASCII coding) is used. If you want to use dftables to generate
53     the character tables as previously, add --enable-rebuild-chartables to the
54     "configure" command. You must do this if you are compiling PCRE to run on a
55     system that uses EBCDIC code.
56 ph10 122
57 ph10 128 There is a discussion about character tables in the README file. The default is
58     not to use dftables so that that there is no problem when cross-compiling.
59    
60    
61 ph10 122 Release 7.0 19-Dec-06
62     ---------------------
63    
64 nigel 93 This release has a new major number because there have been some internal
65     upheavals to facilitate the addition of new optimizations and other facilities,
66     and to make subsequent maintenance and extension easier. Compilation is likely
67     to be a bit slower, but there should be no major effect on runtime performance.
68     Previously compiled patterns are NOT upwards compatible with this release. If
69     you have saved compiled patterns from a previous release, you will have to
70     re-compile them. Important changes that are visible to users are:
71    
72     1. The Unicode property tables have been updated to Unicode 5.0.0, which adds
73     some more scripts.
74    
75     2. The option PCRE_NEWLINE_ANY causes PCRE to recognize any Unicode newline
76     sequence as a newline.
77    
78     3. The \R escape matches a single Unicode newline sequence as a single unit.
79    
80     4. New features that will appear in Perl 5.10 are now in PCRE. These include
81     alternative Perl syntax for named parentheses, and Perl syntax for
82     recursion.
83    
84     5. The C++ wrapper interface has been extended by the addition of a
85     QuoteMeta function and the ability to allow copy construction and
86     assignment.
87    
88     For a complete list of changes, see the ChangeLog file.
89    
90    
91 nigel 91 Release 6.7 04-Jul-06
92     ---------------------
93    
94     The main additions to this release are the ability to use the same name for
95     multiple sets of parentheses, and support for CRLF line endings in both the
96     library and pcregrep (and in pcretest for testing).
97    
98     Thanks to Ian Taylor, the stack usage for many kinds of pattern has been
99     significantly reduced for certain subject strings.
100    
101    
102 nigel 87 Release 6.5 01-Feb-06
103     ---------------------
104    
105     Important changes in this release:
106    
107     1. A number of new features have been added to pcregrep.
108    
109     2. The Unicode property tables have been updated to Unicode 4.1.0, and the
110     supported properties have been extended with script names such as "Arabic",
111     and the derived properties "Any" and "L&". This has necessitated a change to
112     the interal format of compiled patterns. Any saved compiled patterns that
113     use \p or \P must be recompiled.
114    
115     3. The specification of recursion in patterns has been changed so that all
116     recursive subpatterns are automatically treated as atomic groups. Thus, for
117     example, (?R) is treated as if it were (?>(?R)). This is necessary because
118     otherwise there are situations where recursion does not work.
119    
120     See the ChangeLog for a complete list of changes, which include a number of bug
121     fixes and tidies.
122    
123    
124 nigel 77 Release 6.0 07-Jun-05
125     ---------------------
126    
127     The release number has been increased to 6.0 because of the addition of several
128     major new pieces of functionality.
129    
130     A new function, pcre_dfa_exec(), which implements pattern matching using a DFA
131     algorithm, has been added. This has a number of advantages for certain cases,
132     though it does run more slowly, and lacks the ability to capture substrings. On
133     the other hand, it does find all matches, not just the first, and it works
134     better for partial matching. The pcrematching man page discusses the
135     differences.
136    
137     The pcretest program has been enhanced so that it can make use of the new
138     pcre_dfa_exec() matching function and the extra features it provides.
139    
140     The distribution now includes a C++ wrapper library. This is built
141     automatically if a C++ compiler is found. The pcrecpp man page discusses this
142     interface.
143    
144     The code itself has been re-organized into many more files, one for each
145     function, so it no longer requires everything to be linked in when static
146     linkage is used. As a consequence, some internal functions have had to have
147     their names exposed. These functions all have names starting with _pcre_. They
148     are undocumented, and are not intended for use by outside callers.
149    
150     The pcregrep program has been enhanced with new functionality such as
151     multiline-matching and options for output more matching context. See the
152     ChangeLog for a complete list of changes to the library and the utility
153     programs.
154    
155    
156 nigel 75 Release 5.0 13-Sep-04
157     ---------------------
158    
159     The licence under which PCRE is released has been changed to the more
160     conventional "BSD" licence.
161    
162     In the code, some bugs have been fixed, and there are also some major changes
163     in this release (which is why I've increased the number to 5.0). Some changes
164     are internal rearrangements, and some provide a number of new facilities. The
165     new features are:
166    
167     1. There's an "automatic callout" feature that inserts callouts before every
168     item in the regex, and there's a new callout field that gives the position
169     in the pattern - useful for debugging and tracing.
170    
171     2. The extra_data structure can now be used to pass in a set of character
172     tables at exec time. This is useful if compiled regex are saved and re-used
173     at a later time when the tables may not be at the same address. If the
174     default internal tables are used, the pointer saved with the compiled
175     pattern is now set to NULL, which means that you don't need to do anything
176     special unless you are using custom tables.
177    
178     3. It is possible, with some restrictions on the content of the regex, to
179     request "partial" matching. A special return code is given if all of the
180     subject string matched part of the regex. This could be useful for testing
181     an input field as it is being typed.
182    
183     4. There is now some optional support for Unicode character properties, which
184     means that the patterns items such as \p{Lu} and \X can now be used. Only
185     the general category properties are supported. If PCRE is compiled with this
186     support, an additional 90K data structure is include, which increases the
187     size of the library dramatically.
188    
189     5. There is support for saving compiled patterns and re-using them later.
190    
191     6. There is support for running regular expressions that were compiled on a
192     different host with the opposite endianness.
193    
194     7. The pcretest program has been extended to accommodate the new features.
195    
196     The main internal rearrangement is that sequences of literal characters are no
197     longer handled as strings. Instead, each character is handled on its own. This
198     makes some UTF-8 handling easier, and makes the support of partial matching
199     possible. Compiled patterns containing long literal strings will be larger as a
200     result of this change; I hope that performance will not be much affected.
201    
202    
203 nigel 73 Release 4.5 01-Dec-03
204     ---------------------
205    
206     Again mainly a bug-fix and tidying release, with only a couple of new features:
207    
208     1. It's possible now to compile PCRE so that it does not use recursive
209     function calls when matching. Instead it gets memory from the heap. This slows
210     things down, but may be necessary on systems with limited stacks.
211    
212     2. UTF-8 string checking has been tightened to reject overlong sequences and to
213     check that a starting offset points to the start of a character. Failure of the
214     latter returns a new error code: PCRE_ERROR_BADUTF8_OFFSET.
215    
216     3. PCRE can now be compiled for systems that use EBCDIC code.
217    
218    
219 nigel 71 Release 4.4 21-Aug-03
220     ---------------------
221    
222     This is mainly a bug-fix and tidying release. The only new feature is that PCRE
223     checks UTF-8 strings for validity by default. There is an option to suppress
224     this, just in case anybody wants that teeny extra bit of performance.
225    
226    
227     Releases 4.1 - 4.3
228     ------------------
229    
230     Sorry, I forgot about updating the NEWS file for these releases. Please take a
231     look at ChangeLog.
232    
233    
234 nigel 63 Release 4.0 17-Feb-03
235     ---------------------
236    
237     There have been a lot of changes for the 4.0 release, adding additional
238     functionality and mending bugs. Below is a list of the highlights of the new
239     functionality. For full details of these features, please consult the
240     documentation. For a complete list of changes, see the ChangeLog file.
241    
242     1. Support for Perl's \Q...\E escapes.
243    
244     2. "Possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java
245     package. They provide some syntactic sugar for simple cases of "atomic
246     grouping".
247    
248     3. Support for the \G assertion. It is true when the current matching position
249     is at the start point of the match.
250    
251     4. A new feature that provides some of the functionality that Perl provides
252     with (?{...}). The facility is termed a "callout". The way it is done in PCRE
253     is for the caller to provide an optional function, by setting pcre_callout to
254     its entry point. To get the function called, the regex must include (?C) at
255     appropriate points.
256    
257     5. Support for recursive calls to individual subpatterns. This makes it really
258     easy to get totally confused.
259    
260     6. Support for named subpatterns. The Python syntax (?P<name>...) is used to
261     name a group.
262    
263     7. Several extensions to UTF-8 support; it is now fairly complete. There is an
264     option for pcregrep to make it operate in UTF-8 mode.
265    
266     8. The single man page has been split into a number of separate man pages.
267     These also give rise to individual HTML pages which are put in a separate
268     directory. There is an index.html page that lists them all. Some hyperlinking
269     between the pages has been installed.
270    
271    
272 nigel 53 Release 3.5 15-Aug-01
273     ---------------------
274    
275     1. The configuring system has been upgraded to use later versions of autoconf
276     and libtool. By default it builds both a shared and a static library if the OS
277     supports it. You can use --disable-shared or --disable-static on the configure
278     command if you want only one of them.
279    
280     2. The pcretest utility is now installed along with pcregrep because it is
281     useful for users (to test regexs) and by doing this, it automatically gets
282     relinked by libtool. The documentation has been turned into a man page, so
283     there are now .1, .txt, and .html versions in /doc.
284    
285     3. Upgrades to pcregrep:
286     (i) Added long-form option names like gnu grep.
287     (ii) Added --help to list all options with an explanatory phrase.
288     (iii) Added -r, --recursive to recurse into sub-directories.
289     (iv) Added -f, --file to read patterns from a file.
290    
291     4. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
292     script, to force use of CR or LF instead of \n in the source. On non-Unix
293     systems, the value can be set in config.h.
294    
295     5. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
296     absolute limit. Changed the text of the error message to make this clear, and
297     likewise updated the man page.
298    
299     6. The limit of 99 on the number of capturing subpatterns has been removed.
300     The new limit is 65535, which I hope will not be a "real" limit.
301    
302    
303 nigel 49 Release 3.3 01-Aug-00
304     ---------------------
305    
306     There is some support for UTF-8 character strings. This is incomplete and
307     experimental. The documentation describes what is and what is not implemented.
308     Otherwise, this is just a bug-fixing release.
309    
310    
311 nigel 43 Release 3.0 01-Feb-00
312     ---------------------
313 nigel 41
314 nigel 43 1. A "configure" script is now used to configure PCRE for Unix systems. It
315     builds a Makefile, a config.h file, and the pcre-config script.
316    
317     2. PCRE is built as a shared library by default.
318    
319     3. There is support for POSIX classes such as [:alpha:].
320    
321     5. There is an experimental recursion feature.
322    
323 nigel 41 ----------------------------------------------------------------------------
324     IMPORTANT FOR THOSE UPGRADING FROM VERSIONS BEFORE 2.00
325    
326     Please note that there has been a change in the API such that a larger
327     ovector is required at matching time, to provide some additional workspace.
328     The new man page has details. This change was necessary in order to support
329     some of the new functionality in Perl 5.005.
330    
331     IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.00
332    
333     Another (I hope this is the last!) change has been made to the API for the
334     pcre_compile() function. An additional argument has been added to make it
335     possible to pass over a pointer to character tables built in the current
336     locale by pcre_maketables(). To use the default tables, this new arguement
337     should be passed as NULL.
338    
339     IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05
340    
341     Yet another (and again I hope this really is the last) change has been made
342     to the API for the pcre_exec() function. An additional argument has been
343     added to make it possible to start the match other than at the start of the
344     subject string. This is important if there are lookbehinds. The new man
345     page has the details, but you just want to convert existing programs, all
346     you need to do is to stick in a new fifth argument to pcre_exec(), with a
347     value of zero. For example, change
348    
349     pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)
350     to
351     pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)
352    
353     ****

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