Contents of /code/trunk/NEWS

News about PCRE releases
------------------------

Release 6.0 07-Jun-05
---------------------

The release number has been increased to 6.0 because of the addition of several
major new pieces of functionality.

A new function, pcre_dfa_exec(), which implements pattern matching using a DFA
algorithm, has been added. This has a number of advantages for certain cases,
though it does run more slowly, and lacks the ability to capture substrings. On
the other hand, it does find all matches, not just the first, and it works
better for partial matching. The pcrematching man page discusses the
differences.

The pcretest program has been enhanced so that it can make use of the new
pcre_dfa_exec() matching function and the extra features it provides.

The distribution now includes a C++ wrapper library. This is built
automatically if a C++ compiler is found. The pcrecpp man page discusses this
interface.

The code itself has been re-organized into many more files, one for each
function, so it no longer requires everything to be linked in when static
linkage is used. As a consequence, some internal functions have had to have
their names exposed. These functions all have names starting with _pcre_. They
are undocumented, and are not intended for use by outside callers.

The pcregrep program has been enhanced with new functionality such as
multiline-matching and options for output more matching context. See the
ChangeLog for a complete list of changes to the library and the utility
programs.


Release 5.0 13-Sep-04
---------------------

The licence under which PCRE is released has been changed to the more
conventional "BSD" licence.

In the code, some bugs have been fixed, and there are also some major changes
in this release (which is why I've increased the number to 5.0). Some changes
are internal rearrangements, and some provide a number of new facilities. The
new features are:

1. There's an "automatic callout" feature that inserts callouts before every
   item in the regex, and there's a new callout field that gives the position
   in the pattern - useful for debugging and tracing.

2. The extra_data structure can now be used to pass in a set of character
   tables at exec time. This is useful if compiled regex are saved and re-used
   at a later time when the tables may not be at the same address. If the
   default internal tables are used, the pointer saved with the compiled
   pattern is now set to NULL, which means that you don't need to do anything
   special unless you are using custom tables.

3. It is possible, with some restrictions on the content of the regex, to
   request "partial" matching. A special return code is given if all of the
   subject string matched part of the regex. This could be useful for testing
   an input field as it is being typed.

4. There is now some optional support for Unicode character properties, which
   means that the patterns items such as \p{Lu} and \X can now be used. Only
   the general category properties are supported. If PCRE is compiled with this
   support, an additional 90K data structure is include, which increases the
   size of the library dramatically.

5. There is support for saving compiled patterns and re-using them later.

6. There is support for running regular expressions that were compiled on a
   different host with the opposite endianness.

7. The pcretest program has been extended to accommodate the new features.

The main internal rearrangement is that sequences of literal characters are no
longer handled as strings. Instead, each character is handled on its own. This
makes some UTF-8 handling easier, and makes the support of partial matching
possible. Compiled patterns containing long literal strings will be larger as a
result of this change; I hope that performance will not be much affected.


Release 4.5 01-Dec-03
---------------------

Again mainly a bug-fix and tidying release, with only a couple of new features:

1. It's possible now to compile PCRE so that it does not use recursive
function calls when matching. Instead it gets memory from the heap. This slows
things down, but may be necessary on systems with limited stacks.

2. UTF-8 string checking has been tightened to reject overlong sequences and to
check that a starting offset points to the start of a character. Failure of the
latter returns a new error code: PCRE_ERROR_BADUTF8_OFFSET.

3. PCRE can now be compiled for systems that use EBCDIC code.


Release 4.4 21-Aug-03
---------------------

This is mainly a bug-fix and tidying release. The only new feature is that PCRE
checks UTF-8 strings for validity by default. There is an option to suppress
this, just in case anybody wants that teeny extra bit of performance.


Releases 4.1 - 4.3
------------------

Sorry, I forgot about updating the NEWS file for these releases. Please take a
look at ChangeLog.


Release 4.0 17-Feb-03
---------------------

There have been a lot of changes for the 4.0 release, adding additional
functionality and mending bugs. Below is a list of the highlights of the new
functionality. For full details of these features, please consult the
documentation. For a complete list of changes, see the ChangeLog file.

1. Support for Perl's \Q...\E escapes.

2. "Possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java
package. They provide some syntactic sugar for simple cases of "atomic
grouping".

3. Support for the \G assertion. It is true when the current matching position
is at the start point of the match.

4. A new feature that provides some of the functionality that Perl provides
with (?{...}). The facility is termed a "callout". The way it is done in PCRE
is for the caller to provide an optional function, by setting pcre_callout to
its entry point. To get the function called, the regex must include (?C) at
appropriate points.

5. Support for recursive calls to individual subpatterns. This makes it really
easy to get totally confused.

6. Support for named subpatterns. The Python syntax (?P<name>...) is used to
name a group.

7. Several extensions to UTF-8 support; it is now fairly complete. There is an
option for pcregrep to make it operate in UTF-8 mode.

8. The single man page has been split into a number of separate man pages.
These also give rise to individual HTML pages which are put in a separate
directory. There is an index.html page that lists them all. Some hyperlinking
between the pages has been installed.


Release 3.5 15-Aug-01
---------------------

1. The configuring system has been upgraded to use later versions of autoconf
and libtool. By default it builds both a shared and a static library if the OS
supports it. You can use --disable-shared or --disable-static on the configure
command if you want only one of them.

2. The pcretest utility is now installed along with pcregrep because it is
useful for users (to test regexs) and by doing this, it automatically gets
relinked by libtool. The documentation has been turned into a man page, so
there are now .1, .txt, and .html versions in /doc.

3. Upgrades to pcregrep:
   (i)   Added long-form option names like gnu grep.
   (ii)  Added --help to list all options with an explanatory phrase.
   (iii) Added -r, --recursive to recurse into sub-directories.
   (iv)  Added -f, --file to read patterns from a file.

4. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
script, to force use of CR or LF instead of \n in the source. On non-Unix
systems, the value can be set in config.h.

5. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
absolute limit. Changed the text of the error message to make this clear, and
likewise updated the man page.

6. The limit of 99 on the number of capturing subpatterns has been removed.
The new limit is 65535, which I hope will not be a "real" limit.


Release 3.3 01-Aug-00
---------------------

There is some support for UTF-8 character strings. This is incomplete and
experimental. The documentation describes what is and what is not implemented.
Otherwise, this is just a bug-fixing release.


Release 3.0 01-Feb-00
---------------------

1. A "configure" script is now used to configure PCRE for Unix systems. It
builds a Makefile, a config.h file, and the pcre-config script.

2. PCRE is built as a shared library by default.

3. There is support for POSIX classes such as [:alpha:].

5. There is an experimental recursion feature.

----------------------------------------------------------------------------
          IMPORTANT FOR THOSE UPGRADING FROM VERSIONS BEFORE 2.00

Please note that there has been a change in the API such that a larger
ovector is required at matching time, to provide some additional workspace.
The new man page has details. This change was necessary in order to support
some of the new functionality in Perl 5.005.

          IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.00

Another (I hope this is the last!) change has been made to the API for the
pcre_compile() function. An additional argument has been added to make it
possible to pass over a pointer to character tables built in the current
locale by pcre_maketables(). To use the default tables, this new arguement
should be passed as NULL.

          IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05

Yet another (and again I hope this really is the last) change has been made
to the API for the pcre_exec() function. An additional argument has been
added to make it possible to start the match other than at the start of the
subject string. This is important if there are lookbehinds. The new man
page has the details, but you just want to convert existing programs, all
you need to do is to stick in a new fifth argument to pcre_exec(), with a
value of zero. For example, change

  pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)
to
  pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)

****
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	****