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Contents of /code/tags/pcre-7.5/NEWS

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Sat Feb 24 21:41:34 2007 UTC (12 years, 8 months ago) by nigel
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Load pcre-6.7 into code/trunk.
1 News about PCRE releases
2 ------------------------
4 Release 6.7 04-Jul-06
5 ---------------------
7 The main additions to this release are the ability to use the same name for
8 multiple sets of parentheses, and support for CRLF line endings in both the
9 library and pcregrep (and in pcretest for testing).
11 Thanks to Ian Taylor, the stack usage for many kinds of pattern has been
12 significantly reduced for certain subject strings.
15 Release 6.5 01-Feb-06
16 ---------------------
18 Important changes in this release:
20 1. A number of new features have been added to pcregrep.
22 2. The Unicode property tables have been updated to Unicode 4.1.0, and the
23 supported properties have been extended with script names such as "Arabic",
24 and the derived properties "Any" and "L&". This has necessitated a change to
25 the interal format of compiled patterns. Any saved compiled patterns that
26 use \p or \P must be recompiled.
28 3. The specification of recursion in patterns has been changed so that all
29 recursive subpatterns are automatically treated as atomic groups. Thus, for
30 example, (?R) is treated as if it were (?>(?R)). This is necessary because
31 otherwise there are situations where recursion does not work.
33 See the ChangeLog for a complete list of changes, which include a number of bug
34 fixes and tidies.
37 Release 6.0 07-Jun-05
38 ---------------------
40 The release number has been increased to 6.0 because of the addition of several
41 major new pieces of functionality.
43 A new function, pcre_dfa_exec(), which implements pattern matching using a DFA
44 algorithm, has been added. This has a number of advantages for certain cases,
45 though it does run more slowly, and lacks the ability to capture substrings. On
46 the other hand, it does find all matches, not just the first, and it works
47 better for partial matching. The pcrematching man page discusses the
48 differences.
50 The pcretest program has been enhanced so that it can make use of the new
51 pcre_dfa_exec() matching function and the extra features it provides.
53 The distribution now includes a C++ wrapper library. This is built
54 automatically if a C++ compiler is found. The pcrecpp man page discusses this
55 interface.
57 The code itself has been re-organized into many more files, one for each
58 function, so it no longer requires everything to be linked in when static
59 linkage is used. As a consequence, some internal functions have had to have
60 their names exposed. These functions all have names starting with _pcre_. They
61 are undocumented, and are not intended for use by outside callers.
63 The pcregrep program has been enhanced with new functionality such as
64 multiline-matching and options for output more matching context. See the
65 ChangeLog for a complete list of changes to the library and the utility
66 programs.
69 Release 5.0 13-Sep-04
70 ---------------------
72 The licence under which PCRE is released has been changed to the more
73 conventional "BSD" licence.
75 In the code, some bugs have been fixed, and there are also some major changes
76 in this release (which is why I've increased the number to 5.0). Some changes
77 are internal rearrangements, and some provide a number of new facilities. The
78 new features are:
80 1. There's an "automatic callout" feature that inserts callouts before every
81 item in the regex, and there's a new callout field that gives the position
82 in the pattern - useful for debugging and tracing.
84 2. The extra_data structure can now be used to pass in a set of character
85 tables at exec time. This is useful if compiled regex are saved and re-used
86 at a later time when the tables may not be at the same address. If the
87 default internal tables are used, the pointer saved with the compiled
88 pattern is now set to NULL, which means that you don't need to do anything
89 special unless you are using custom tables.
91 3. It is possible, with some restrictions on the content of the regex, to
92 request "partial" matching. A special return code is given if all of the
93 subject string matched part of the regex. This could be useful for testing
94 an input field as it is being typed.
96 4. There is now some optional support for Unicode character properties, which
97 means that the patterns items such as \p{Lu} and \X can now be used. Only
98 the general category properties are supported. If PCRE is compiled with this
99 support, an additional 90K data structure is include, which increases the
100 size of the library dramatically.
102 5. There is support for saving compiled patterns and re-using them later.
104 6. There is support for running regular expressions that were compiled on a
105 different host with the opposite endianness.
107 7. The pcretest program has been extended to accommodate the new features.
109 The main internal rearrangement is that sequences of literal characters are no
110 longer handled as strings. Instead, each character is handled on its own. This
111 makes some UTF-8 handling easier, and makes the support of partial matching
112 possible. Compiled patterns containing long literal strings will be larger as a
113 result of this change; I hope that performance will not be much affected.
116 Release 4.5 01-Dec-03
117 ---------------------
119 Again mainly a bug-fix and tidying release, with only a couple of new features:
121 1. It's possible now to compile PCRE so that it does not use recursive
122 function calls when matching. Instead it gets memory from the heap. This slows
123 things down, but may be necessary on systems with limited stacks.
125 2. UTF-8 string checking has been tightened to reject overlong sequences and to
126 check that a starting offset points to the start of a character. Failure of the
127 latter returns a new error code: PCRE_ERROR_BADUTF8_OFFSET.
129 3. PCRE can now be compiled for systems that use EBCDIC code.
132 Release 4.4 21-Aug-03
133 ---------------------
135 This is mainly a bug-fix and tidying release. The only new feature is that PCRE
136 checks UTF-8 strings for validity by default. There is an option to suppress
137 this, just in case anybody wants that teeny extra bit of performance.
140 Releases 4.1 - 4.3
141 ------------------
143 Sorry, I forgot about updating the NEWS file for these releases. Please take a
144 look at ChangeLog.
147 Release 4.0 17-Feb-03
148 ---------------------
150 There have been a lot of changes for the 4.0 release, adding additional
151 functionality and mending bugs. Below is a list of the highlights of the new
152 functionality. For full details of these features, please consult the
153 documentation. For a complete list of changes, see the ChangeLog file.
155 1. Support for Perl's \Q...\E escapes.
157 2. "Possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java
158 package. They provide some syntactic sugar for simple cases of "atomic
159 grouping".
161 3. Support for the \G assertion. It is true when the current matching position
162 is at the start point of the match.
164 4. A new feature that provides some of the functionality that Perl provides
165 with (?{...}). The facility is termed a "callout". The way it is done in PCRE
166 is for the caller to provide an optional function, by setting pcre_callout to
167 its entry point. To get the function called, the regex must include (?C) at
168 appropriate points.
170 5. Support for recursive calls to individual subpatterns. This makes it really
171 easy to get totally confused.
173 6. Support for named subpatterns. The Python syntax (?P<name>...) is used to
174 name a group.
176 7. Several extensions to UTF-8 support; it is now fairly complete. There is an
177 option for pcregrep to make it operate in UTF-8 mode.
179 8. The single man page has been split into a number of separate man pages.
180 These also give rise to individual HTML pages which are put in a separate
181 directory. There is an index.html page that lists them all. Some hyperlinking
182 between the pages has been installed.
185 Release 3.5 15-Aug-01
186 ---------------------
188 1. The configuring system has been upgraded to use later versions of autoconf
189 and libtool. By default it builds both a shared and a static library if the OS
190 supports it. You can use --disable-shared or --disable-static on the configure
191 command if you want only one of them.
193 2. The pcretest utility is now installed along with pcregrep because it is
194 useful for users (to test regexs) and by doing this, it automatically gets
195 relinked by libtool. The documentation has been turned into a man page, so
196 there are now .1, .txt, and .html versions in /doc.
198 3. Upgrades to pcregrep:
199 (i) Added long-form option names like gnu grep.
200 (ii) Added --help to list all options with an explanatory phrase.
201 (iii) Added -r, --recursive to recurse into sub-directories.
202 (iv) Added -f, --file to read patterns from a file.
204 4. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
205 script, to force use of CR or LF instead of \n in the source. On non-Unix
206 systems, the value can be set in config.h.
208 5. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
209 absolute limit. Changed the text of the error message to make this clear, and
210 likewise updated the man page.
212 6. The limit of 99 on the number of capturing subpatterns has been removed.
213 The new limit is 65535, which I hope will not be a "real" limit.
216 Release 3.3 01-Aug-00
217 ---------------------
219 There is some support for UTF-8 character strings. This is incomplete and
220 experimental. The documentation describes what is and what is not implemented.
221 Otherwise, this is just a bug-fixing release.
224 Release 3.0 01-Feb-00
225 ---------------------
227 1. A "configure" script is now used to configure PCRE for Unix systems. It
228 builds a Makefile, a config.h file, and the pcre-config script.
230 2. PCRE is built as a shared library by default.
232 3. There is support for POSIX classes such as [:alpha:].
234 5. There is an experimental recursion feature.
236 ----------------------------------------------------------------------------
239 Please note that there has been a change in the API such that a larger
240 ovector is required at matching time, to provide some additional workspace.
241 The new man page has details. This change was necessary in order to support
242 some of the new functionality in Perl 5.005.
246 Another (I hope this is the last!) change has been made to the API for the
247 pcre_compile() function. An additional argument has been added to make it
248 possible to pass over a pointer to character tables built in the current
249 locale by pcre_maketables(). To use the default tables, this new arguement
250 should be passed as NULL.
254 Yet another (and again I hope this really is the last) change has been made
255 to the API for the pcre_exec() function. An additional argument has been
256 added to make it possible to start the match other than at the start of the
257 subject string. This is important if there are lookbehinds. The new man
258 page has the details, but you just want to convert existing programs, all
259 you need to do is to stick in a new fifth argument to pcre_exec(), with a
260 value of zero. For example, change
262 pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)
263 to
264 pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)
266 ****

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