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Sat Feb 24 21:40:45 2007 UTC (7 years, 8 months ago) by nigel
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Load pcre-6.0 into code/trunk.

1 News about PCRE releases
2 ------------------------
3
4 Release 6.0 07-Jun-05
5 ---------------------
6
7 The release number has been increased to 6.0 because of the addition of several
8 major new pieces of functionality.
9
10 A new function, pcre_dfa_exec(), which implements pattern matching using a DFA
11 algorithm, has been added. This has a number of advantages for certain cases,
12 though it does run more slowly, and lacks the ability to capture substrings. On
13 the other hand, it does find all matches, not just the first, and it works
14 better for partial matching. The pcrematching man page discusses the
15 differences.
16
17 The pcretest program has been enhanced so that it can make use of the new
18 pcre_dfa_exec() matching function and the extra features it provides.
19
20 The distribution now includes a C++ wrapper library. This is built
21 automatically if a C++ compiler is found. The pcrecpp man page discusses this
22 interface.
23
24 The code itself has been re-organized into many more files, one for each
25 function, so it no longer requires everything to be linked in when static
26 linkage is used. As a consequence, some internal functions have had to have
27 their names exposed. These functions all have names starting with _pcre_. They
28 are undocumented, and are not intended for use by outside callers.
29
30 The pcregrep program has been enhanced with new functionality such as
31 multiline-matching and options for output more matching context. See the
32 ChangeLog for a complete list of changes to the library and the utility
33 programs.
34
35
36 Release 5.0 13-Sep-04
37 ---------------------
38
39 The licence under which PCRE is released has been changed to the more
40 conventional "BSD" licence.
41
42 In the code, some bugs have been fixed, and there are also some major changes
43 in this release (which is why I've increased the number to 5.0). Some changes
44 are internal rearrangements, and some provide a number of new facilities. The
45 new features are:
46
47 1. There's an "automatic callout" feature that inserts callouts before every
48 item in the regex, and there's a new callout field that gives the position
49 in the pattern - useful for debugging and tracing.
50
51 2. The extra_data structure can now be used to pass in a set of character
52 tables at exec time. This is useful if compiled regex are saved and re-used
53 at a later time when the tables may not be at the same address. If the
54 default internal tables are used, the pointer saved with the compiled
55 pattern is now set to NULL, which means that you don't need to do anything
56 special unless you are using custom tables.
57
58 3. It is possible, with some restrictions on the content of the regex, to
59 request "partial" matching. A special return code is given if all of the
60 subject string matched part of the regex. This could be useful for testing
61 an input field as it is being typed.
62
63 4. There is now some optional support for Unicode character properties, which
64 means that the patterns items such as \p{Lu} and \X can now be used. Only
65 the general category properties are supported. If PCRE is compiled with this
66 support, an additional 90K data structure is include, which increases the
67 size of the library dramatically.
68
69 5. There is support for saving compiled patterns and re-using them later.
70
71 6. There is support for running regular expressions that were compiled on a
72 different host with the opposite endianness.
73
74 7. The pcretest program has been extended to accommodate the new features.
75
76 The main internal rearrangement is that sequences of literal characters are no
77 longer handled as strings. Instead, each character is handled on its own. This
78 makes some UTF-8 handling easier, and makes the support of partial matching
79 possible. Compiled patterns containing long literal strings will be larger as a
80 result of this change; I hope that performance will not be much affected.
81
82
83 Release 4.5 01-Dec-03
84 ---------------------
85
86 Again mainly a bug-fix and tidying release, with only a couple of new features:
87
88 1. It's possible now to compile PCRE so that it does not use recursive
89 function calls when matching. Instead it gets memory from the heap. This slows
90 things down, but may be necessary on systems with limited stacks.
91
92 2. UTF-8 string checking has been tightened to reject overlong sequences and to
93 check that a starting offset points to the start of a character. Failure of the
94 latter returns a new error code: PCRE_ERROR_BADUTF8_OFFSET.
95
96 3. PCRE can now be compiled for systems that use EBCDIC code.
97
98
99 Release 4.4 21-Aug-03
100 ---------------------
101
102 This is mainly a bug-fix and tidying release. The only new feature is that PCRE
103 checks UTF-8 strings for validity by default. There is an option to suppress
104 this, just in case anybody wants that teeny extra bit of performance.
105
106
107 Releases 4.1 - 4.3
108 ------------------
109
110 Sorry, I forgot about updating the NEWS file for these releases. Please take a
111 look at ChangeLog.
112
113
114 Release 4.0 17-Feb-03
115 ---------------------
116
117 There have been a lot of changes for the 4.0 release, adding additional
118 functionality and mending bugs. Below is a list of the highlights of the new
119 functionality. For full details of these features, please consult the
120 documentation. For a complete list of changes, see the ChangeLog file.
121
122 1. Support for Perl's \Q...\E escapes.
123
124 2. "Possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java
125 package. They provide some syntactic sugar for simple cases of "atomic
126 grouping".
127
128 3. Support for the \G assertion. It is true when the current matching position
129 is at the start point of the match.
130
131 4. A new feature that provides some of the functionality that Perl provides
132 with (?{...}). The facility is termed a "callout". The way it is done in PCRE
133 is for the caller to provide an optional function, by setting pcre_callout to
134 its entry point. To get the function called, the regex must include (?C) at
135 appropriate points.
136
137 5. Support for recursive calls to individual subpatterns. This makes it really
138 easy to get totally confused.
139
140 6. Support for named subpatterns. The Python syntax (?P<name>...) is used to
141 name a group.
142
143 7. Several extensions to UTF-8 support; it is now fairly complete. There is an
144 option for pcregrep to make it operate in UTF-8 mode.
145
146 8. The single man page has been split into a number of separate man pages.
147 These also give rise to individual HTML pages which are put in a separate
148 directory. There is an index.html page that lists them all. Some hyperlinking
149 between the pages has been installed.
150
151
152 Release 3.5 15-Aug-01
153 ---------------------
154
155 1. The configuring system has been upgraded to use later versions of autoconf
156 and libtool. By default it builds both a shared and a static library if the OS
157 supports it. You can use --disable-shared or --disable-static on the configure
158 command if you want only one of them.
159
160 2. The pcretest utility is now installed along with pcregrep because it is
161 useful for users (to test regexs) and by doing this, it automatically gets
162 relinked by libtool. The documentation has been turned into a man page, so
163 there are now .1, .txt, and .html versions in /doc.
164
165 3. Upgrades to pcregrep:
166 (i) Added long-form option names like gnu grep.
167 (ii) Added --help to list all options with an explanatory phrase.
168 (iii) Added -r, --recursive to recurse into sub-directories.
169 (iv) Added -f, --file to read patterns from a file.
170
171 4. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
172 script, to force use of CR or LF instead of \n in the source. On non-Unix
173 systems, the value can be set in config.h.
174
175 5. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
176 absolute limit. Changed the text of the error message to make this clear, and
177 likewise updated the man page.
178
179 6. The limit of 99 on the number of capturing subpatterns has been removed.
180 The new limit is 65535, which I hope will not be a "real" limit.
181
182
183 Release 3.3 01-Aug-00
184 ---------------------
185
186 There is some support for UTF-8 character strings. This is incomplete and
187 experimental. The documentation describes what is and what is not implemented.
188 Otherwise, this is just a bug-fixing release.
189
190
191 Release 3.0 01-Feb-00
192 ---------------------
193
194 1. A "configure" script is now used to configure PCRE for Unix systems. It
195 builds a Makefile, a config.h file, and the pcre-config script.
196
197 2. PCRE is built as a shared library by default.
198
199 3. There is support for POSIX classes such as [:alpha:].
200
201 5. There is an experimental recursion feature.
202
203 ----------------------------------------------------------------------------
204 IMPORTANT FOR THOSE UPGRADING FROM VERSIONS BEFORE 2.00
205
206 Please note that there has been a change in the API such that a larger
207 ovector is required at matching time, to provide some additional workspace.
208 The new man page has details. This change was necessary in order to support
209 some of the new functionality in Perl 5.005.
210
211 IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.00
212
213 Another (I hope this is the last!) change has been made to the API for the
214 pcre_compile() function. An additional argument has been added to make it
215 possible to pass over a pointer to character tables built in the current
216 locale by pcre_maketables(). To use the default tables, this new arguement
217 should be passed as NULL.
218
219 IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05
220
221 Yet another (and again I hope this really is the last) change has been made
222 to the API for the pcre_exec() function. An additional argument has been
223 added to make it possible to start the match other than at the start of the
224 subject string. This is important if there are lookbehinds. The new man
225 page has the details, but you just want to convert existing programs, all
226 you need to do is to stick in a new fifth argument to pcre_exec(), with a
227 value of zero. For example, change
228
229 pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)
230 to
231 pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)
232
233 ****

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