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revision 19 by nigel, Sat Feb 24 21:38:33 2007 UTC revision 340 by ph10, Fri Apr 18 20:00:21 2008 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.7 05-Mar-08
5    ---------------------
7    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
8        a string to a long long, pretend we don't even have a long long." This is
9        done by checking for the strtoq, strtoll, and _strtoi64 functions.
11    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
12        pre-7.6 versions, which defined a global no_arg variable instead of putting
13        it in the RE class. (See also #8 below.)
15    3.  Remove a line of dead code, identified by coverity and reported by Nuno
16        Lopes.
18    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
20        (1) The include/exclude patterns were being applied to the whole pathnames
21            of files, instead of just to the final components.
23        (2) If there was more than one level of directory, the subdirectories were
24            skipped unless they satisfied the include/exclude conditions. This is
25            inconsistent with GNU grep (and could even be seen as contrary to the
26            pcregrep specification - which I improved to make it absolutely clear).
27            The action now is always to scan all levels of directory, and just
28            apply the include/exclude patterns to regular files.
30    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
31        --exclude_dir in the tests to avoid scanning .svn directories.
33    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
34        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
35        doesn't support NULs in patterns.
37    7.  Added some missing "const"s to declarations of static tables in
38        pcre_compile.c and pcre_dfa_exec.c.
40    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
41        caused by fix #2  above. (Subsequently also a second patch to fix the
42        first patch. And a third patch - this was a messy problem.)
44    9.  Applied Craig's patch to remove the use of push_back().
46    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
47        matching function regexec().
49    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
50        which, however, unlike Perl's \g{...}, are subroutine calls, not back
51        references. PCRE supports relative numbers with this syntax (I don't think
52        Oniguruma does).
54    12. Previously, a group with a zero repeat such as (...){0} was completely
55        omitted from the compiled regex. However, this means that if the group
56        was called as a subroutine from elsewhere in the pattern, things went wrong
57        (an internal error was given). Such groups are now left in the compiled
58        pattern, with a new opcode that causes them to be skipped at execution
59        time.
61    13. Added the PCRE_JAVASCRIPT_COMPAT option. This currently does two things:
62        (a) A lone ] character is dis-allowed (Perl treats it as data).
63        (b) A back reference to an unmatched subpattern matches an empty string
64            (Perl fails the current match path).
66    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
67        non-existent subpattern following a character class starting with ']' and
68        containing () gave an internal compiling error instead of "reference to
69        non-existent subpattern". Fortunately, when the pattern did exist, the
70        compiled code was correct. (When scanning forwards to check for the
71        existencd of the subpattern, it was treating the data ']' as terminating
72        the class, so got the count wrong. When actually compiling, the reference
73        was subsequently set up correctly.)
76    Version 7.6 28-Jan-08
77    ---------------------
79    1.  A character class containing a very large number of characters with
80        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
81        overflow.
83    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
84        HAVE_LONG_LONG is not defined.
86    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
87        bring them up to date and include new features. This patch includes:
89        - Fixed PH's badly added libz and libbz2 support.
90        - Fixed a problem with static linking.
91        - Added pcredemo. [But later removed - see 7 below.]
92        - Fixed dftables problem and added an option.
93        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
94            HAVE_LONG_LONG.
95        - Added readline support for pcretest.
96        - Added an listing of the option settings after cmake has run.
98    4.  A user submitted a patch to Makefile that makes it easy to create
99        "pcre.dll" under mingw when using Configure/Make. I added stuff to
100        Makefile.am that cause it to include this special target, without
101        affecting anything else. Note that the same mingw target plus all
102        the other distribution libraries and programs are now supported
103        when configuring with CMake (see 6 below) instead of with
104        Configure/Make.
106    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
107        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
108        exported in the Windows port". It has not yet been confirmed that the patch
109        solves the problem, but it does no harm.
111    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
112        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
113        with CMake, and also correct the comment about stack recursion.
115    7.  Remove the automatic building of pcredemo from the ./configure system and
116        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
117        of a program that users should build themselves after PCRE is installed, so
118        building it automatically is not really right. What is more, it gave
119        trouble in some build environments.
121    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
124    Version 7.5 10-Jan-08
125    ---------------------
127    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
128        values in parens when parsing an RE using the C++ wrapper."
130    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
131        Characters greater than 255 were excluded from the class instead of being
132        included.
134    3.  The same bug as (2) above applied to negated POSIX classes such as
135        [:^space:].
137    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
138        defined or documented. It seems to have been a typo for PCRE_STATIC, so
139        I have changed it.
141    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
142        first named subpattern) and a construct such as (?&a) would reference the
143        first named subpattern whose name started with "a" (in other words, the
144        length check was missing). Both these problems are fixed. "Subpattern name
145        expected" is now given for (?&) (a zero-length name), and this patch also
146        makes it give the same error for \k'' (previously it complained that that
147        was a reference to a non-existent subpattern).
149    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
150        this is right because (?- can be followed by option settings as well as by
151        digits. I have, however, made the messages clearer.
153    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
154        than the number used in the conditional) now cause a compile-time error.
155        This is actually not compatible with Perl, which accepts such patterns, but
156        treats the conditional as always being FALSE (as PCRE used to), but it
157        seems to me that giving a diagnostic is better.
159    8.  Change "alphameric" to the more common word "alphanumeric" in comments
160        and messages.
162    9.  Fix two occurrences of "backslash" in comments that should have been
163        "backspace".
165    10. Remove two redundant lines of code that can never be obeyed (their function
166        was moved elsewhere).
168    11. The program that makes PCRE's Unicode character property table had a bug
169        which caused it to generate incorrect table entries for sequences of
170        characters that have the same character type, but are in different scripts.
171        It amalgamated them into a single range, with the script of the first of
172        them. In other words, some characters were in the wrong script. There were
173        thirteen such cases, affecting characters in the following ranges:
175          U+002b0 - U+002c1
176          U+0060c - U+0060d
177          U+0061e - U+00612
178          U+0064b - U+0065e
179          U+0074d - U+0076d
180          U+01800 - U+01805
181          U+01d00 - U+01d77
182          U+01d9b - U+01dbf
183          U+0200b - U+0200f
184          U+030fc - U+030fe
185          U+03260 - U+0327f
186          U+0fb46 - U+0fbb1
187          U+10450 - U+1049d
189    12. The -o option (show only the matching part of a line) for pcregrep was not
190        compatible with GNU grep in that, if there was more than one match in a
191        line, it showed only the first of them. It now behaves in the same way as
192        GNU grep.
194    13. If the -o and -v options were combined for pcregrep, it printed a blank
195        line for every non-matching line. GNU grep prints nothing, and pcregrep now
196        does the same. The return code can be used to tell if there were any
197        non-matching lines.
199    14. Added --file-offsets and --line-offsets to pcregrep.
201    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
202        infinitely looping recursion. The bug was that positive lookaheads were not
203        being skipped when checking for a possible empty match (negative lookaheads
204        and both kinds of lookbehind were skipped).
206    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
207        inclusion of <windows.h> to before rather than after the definition of
208        INVALID_FILE_ATTRIBUTES (patch from David Byron).
210    17. Specifying a possessive quantifier with a specific limit for a Unicode
211        character property caused pcre_compile() to compile bad code, which led at
212        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
213        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
214        caused the error; without that there was no problem.
216    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
218    19. Added --enable-pcretest-libreadline.
220    20. In pcrecpp.cc, the variable 'count' was incremented twice in
221        RE::GlobalReplace(). As a result, the number of replacements returned was
222        double what it should be. I removed one of the increments, but Craig sent a
223        later patch that removed the other one (the right fix) and added unit tests
224        that check the return values (which was not done before).
226    21. Several CMake things:
228        (1) Arranged that, when cmake is used on Unix, the libraries end up with
229            the names libpcre and libpcreposix, not just pcre and pcreposix.
231        (2) The above change means that pcretest and pcregrep are now correctly
232            linked with the newly-built libraries, not previously installed ones.
236    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
237        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
238        UTF-8 newline character). The key issue is that the pattern starts .*;
239        this means that the match must be either at the beginning, or after a
240        newline. The bug was in the code for advancing after a failed match and
241        checking that the new position followed a newline. It was not taking
242        account of UTF-8 characters correctly.
244    23. PCRE was behaving differently from Perl in the way it recognized POSIX
245        character classes. PCRE was not treating the sequence [:...:] as a
246        character class unless the ... were all letters. Perl, however, seems to
247        allow any characters between [: and :], though of course it rejects as
248        unknown any "names" that contain non-letters, because all the known class
249        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
250        for example, whereas PCRE did not - it did not recognize a POSIX character
251        class. This seemed a bit dangerous, so the code has been changed to be
252        closer to Perl. The behaviour is not identical to Perl, because PCRE will
253        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
254        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
255        Perl does, and where it didn't before.
257    24. Rewrite so as to remove the single use of %n from pcregrep because in some
258        Windows environments %n is disabled by default.
261    Version 7.4 21-Sep-07
262    ---------------------
264    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
265        means that a class such as [\s] counted as "explicit reference to CR or
266        LF". That isn't really right - the whole point of the change was to try to
267        help when there was an actual mention of one of the two characters. So now
268        the change happens only if \r or \n (or a literal CR or LF) character is
269        encountered.
271    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
272        of both had grown to the point where there were only 3 bits left.
273        Fortunately, there was spare space in the data structure, and so I have
274        moved the internal flags into a new 16-bit field to free up more option
275        bits.
277    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
278        but did not set the internal JCHANGED flag - either of these is enough to
279        control the way the "get" function works - but the PCRE_INFO_JCHANGED
280        facility is supposed to tell if (?J) was ever used, so now (?J) at the
281        start sets both bits.
283    4.  Added options (at build time, compile time, exec time) to change \R from
284        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
286    5.  doc/pcresyntax.html was missing from the distribution.
288    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
289        compatibility, even though it is no longer used.
291    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
292        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
293        windows.h file is present (where different names are used). [This was
294        reversed later after testing - see 16 below.]
296    8.  Changed all #include <config.h> to #include "config.h". There were also
297        some further <pcre.h> cases that I changed to "pcre.h".
299    9.  When pcregrep was used with the --colour option, it missed the line ending
300        sequence off the lines that it output.
302    10. It was pointed out to me that arrays of string pointers cause lots of
303        relocations when a shared library is dynamically loaded. A technique of
304        using a single long string with a table of offsets can drastically reduce
305        these. I have refactored PCRE in four places to do this. The result is
306        dramatic:
308          Originally:                          290
309          After changing UCP table:            187
310          After changing error message table:   43
311          After changing table of "verbs"       36
312          After changing table of Posix names   22
314        Thanks to the folks working on Gregex for glib for this insight.
316    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
317        unicode-properties was also set.
319    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
321    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
322        checked only for CRLF.
324    14. Added casts to pcretest.c to avoid compiler warnings.
326    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
328    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
329        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
330        entirely. This removes changes made in 7 above.
332    17. The CMake files have been updated, and there is now more information about
333        building with CMake in the NON-UNIX-USE document.
336    Version 7.3 28-Aug-07
337    ---------------------
339     1. In the rejigging of the build system that eventually resulted in 7.1, the
340        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
341        brackets there is not right, since it causes compilers to look for an
342        installed pcre.h, not the version that is in the source that is being
343        compiled (which of course may be different). I have changed it back to:
345          #include "pcre.h"
347        I have a vague recollection that the change was concerned with compiling in
348        different directories, but in the new build system, that is taken care of
349        by the VPATH setting the Makefile.
351     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
352        when the subject happened to end in the byte 0x85 (e.g. if the last
353        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
354        characters but of course it shouldn't be taken as a newline when it is part
355        of another character. The bug was that, for an unlimited repeat of . in
356        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
357        characters when looking for a newline.
359     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
361     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
362        in debug output.
364     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
365        long printing in the pcrecpp unittest when running under MinGW.
367     6. ESC_K was left out of the EBCDIC table.
369     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
370        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
371        limit also applies to "virtual nesting" when a pattern is recursive, and in
372        this case 1000 isn't so big. I have been able to remove this limit at the
373        expense of backing off one optimization in certain circumstances. Normally,
374        when pcre_exec() would call its internal match() function recursively and
375        immediately return the result unconditionally, it uses a "tail recursion"
376        feature to save stack. However, when a subpattern that can match an empty
377        string has an unlimited repetition quantifier, it no longer makes this
378        optimization. That gives it a stack frame in which to save the data for
379        checking that an empty string has been matched. Previously this was taken
380        from the 1000-entry workspace that had been reserved. So now there is no
381        explicit limit, but more stack is used.
383     8. Applied Daniel's patches to solve problems with the import/export magic
384        syntax that is required for Windows, and which was going wrong for the
385        pcreposix and pcrecpp parts of the library. These were overlooked when this
386        problem was solved for the main library.
388     9. There were some crude static tests to avoid integer overflow when computing
389        the size of patterns that contain repeated groups with explicit upper
390        limits. As the maximum quantifier is 65535, the maximum group length was
391        set at 30,000 so that the product of these two numbers did not overflow a
392        32-bit integer. However, it turns out that people want to use groups that
393        are longer than 30,000 bytes (though not repeat them that many times).
394        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
395        made it possible to implement the integer overflow checks in a much more
396        dynamic way, which I have now done. The artificial limitation on group
397        length has been removed - we now have only the limit on the total length of
398        the compiled pattern, which depends on the LINK_SIZE setting.
400    10. Fixed a bug in the documentation for get/copy named substring when
401        duplicate names are permitted. If none of the named substrings are set, the
402        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
403        empty string.
405    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
406        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
407        because the ] is interpreted as the first data character and the
408        terminating ] is not found. PCRE has been made compatible with Perl in this
409        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
410        cause memory overwriting.
412    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
413        string has been matched (to stop an infinite loop). It was not recognizing
414        a conditional subpattern that could match an empty string if that
415        subpattern was within another subpattern. For example, it looped when
416        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
417        condition was not nested. This bug has been fixed.
419    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
420        past the start of the subject in the presence of bytes with the top bit
421        set, for example "\x8aBCD".
423    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
424        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
426    14. Optimized (?!) to (*FAIL).
428    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
429        This restricts code points to be within the range 0 to 0x10FFFF, excluding
430        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
431        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
432        does: it's just the validity check that is more restrictive.
434    16. Inserted checks for integer overflows during escape sequence (backslash)
435        processing, and also fixed erroneous offset values for syntax errors during
436        backslash processing.
438    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
439        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
441    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
442        caused an overrun.
444    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
445        something other than just ASCII characters) inside a group that had an
446        unlimited repeat caused a loop at compile time (while checking to see
447        whether the group could match an empty string).
449    20. Debugging a pattern containing \p or \P could cause a crash. For example,
450        [\P{Any}] did so. (Error in the code for printing property names.)
452    21. An orphan \E inside a character class could cause a crash.
454    22. A repeated capturing bracket such as (A)? could cause a wild memory
455        reference during compilation.
457    23. There are several functions in pcre_compile() that scan along a compiled
458        expression for various reasons (e.g. to see if it's fixed length for look
459        behind). There were bugs in these functions when a repeated \p or \P was
460        present in the pattern. These operators have additional parameters compared
461        with \d, etc, and these were not being taken into account when moving along
462        the compiled data. Specifically:
464        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
465            length.
467        (b) An item such as \pL+ within a repeated group could cause crashes or
468            loops.
470        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
471            "reference to non-existent subpattern" error.
473        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
475    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
476        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
478    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
480    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
481        character were causing crashes (broken optimization).
483    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
484        \p or \P) caused a compile-time loop.
486    28. More problems have arisen in unanchored patterns when CRLF is a valid line
487        break. For example, the unstudied pattern [\r\n]A does not match the string
488        "\r\nA" because change 7.0/46 below moves the current point on by two
489        characters after failing to match at the start. However, the pattern \nA
490        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
491        the same is true. There doesn't seem any very clean way out of this, but
492        what I have chosen to do makes the common cases work: PCRE now takes note
493        of whether there can be an explicit match for \r or \n anywhere in the
494        pattern, and if so, 7.0/46 no longer applies. As part of this change,
495        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
496        pattern has explicit CR or LF references.
498    29. Added (*CR) etc for changing newline setting at start of pattern.
501    Version 7.2 19-Jun-07
502    ---------------------
504     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
505        which is apparently normally available under Windows.
507     2. Re-jig the pcregrep tests with different newline settings in an attempt
508        to make them independent of the local environment's newline setting.
510     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
512     4. Some of the "internals" tests were previously cut out when the link size
513        was not 2, because the output contained actual offsets. The recent new
514        "Z" feature of pcretest means that these can be cut out, making the tests
515        usable with all link sizes.
517     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
518        stack recursion. This gives a massive performance boost under BSD, but just
519        a small improvement under Linux. However, it saves one field in the frame
520        in all cases.
522     6. Added more features from the forthcoming Perl 5.10:
524        (a) (?-n) (where n is a string of digits) is a relative subroutine or
525            recursion call. It refers to the nth most recently opened parentheses.
527        (b) (?+n) is also a relative subroutine call; it refers to the nth next
528            to be opened parentheses.
530        (c) Conditions that refer to capturing parentheses can be specified
531            relatively, for example, (?(-2)... or (?(+3)...
533        (d) \K resets the start of the current match so that everything before
534            is not part of it.
536        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
538        (f) \g{name} is another synonym - part of Perl 5.10's unification of
539            reference syntax.
541        (g) (?| introduces a group in which the numbering of parentheses in each
542            alternative starts with the same number.
544        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
546     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
549     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
550        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
551        for detecting groups that can match an empty string.
553     9. A pattern with a very large number of alternatives (more than several
554        hundred) was running out of internal workspace during the pre-compile
555        phase, where pcre_compile() figures out how much memory will be needed. A
556        bit of new cunning has reduced the workspace needed for groups with
557        alternatives. The 1000-alternative test pattern now uses 12 bytes of
558        workspace instead of running out of the 4096 that are available.
560    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
562    11. Applied patch from Google to remove an optimization that didn't quite work.
563        The report of the bug said:
565          pcrecpp::RE("a*").FullMatch("aaa") matches, while
566          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
567          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
569    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
570        it matched the wrong number of bytes.
573    Version 7.1 24-Apr-07
574    ---------------------
576     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
577        that is more "standard", making use of automake and other Autotools. There
578        is some re-arrangement of the files and adjustment of comments consequent
579        on this.
581     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
582        for recursive directory scanning broke on some systems because the files
583        are not scanned in any specific order and on different systems the order
584        was different. A call to "sort" has been inserted into RunGrepTest for the
585        approprate test as a short-term fix. In the longer term there may be an
586        alternative.
588     3. I had an email from Eric Raymond about problems translating some of PCRE's
589        man pages to HTML (despite the fact that I distribute HTML pages, some
590        people do their own conversions for various reasons). The problems
591        concerned the use of low-level troff macros .br and .in. I have therefore
592        removed all such uses from the man pages (some were redundant, some could
593        be replaced by .nf/.fi pairs). The 132html script that I use to generate
594        HTML has been updated to handle .nf/.fi and to complain if it encounters
595        .br or .in.
597     4. Updated comments in configure.ac that get placed in config.h.in and also
598        arranged for config.h to be included in the distribution, with the name
599        config.h.generic, for the benefit of those who have to compile without
600        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
602     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
603        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
604        makevp.bat for the current PCRE, using the additional files
605        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
607     6. A Windows user reported a minor discrepancy with test 2, which turned out
608        to be caused by a trailing space on an input line that had got lost in his
609        copy. The trailing space was an accident, so I've just removed it.
611     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
612        that is needed.
614     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
615        as "const" (a) because they are and (b) because it helps the PHP
616        maintainers who have recently made a script to detect big data structures
617        in the php code that should be moved to the .rodata section. I remembered
618        to update Builducptable as well, so it won't revert if ucptable.h is ever
619        re-created.
621     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
622        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
623        order to be able to cut out the UTF-8 tables in the latter when UTF-8
624        support is not required. This saves 1.5-2K of code, which is important in
625        some applications.
627        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
628        so as not to refer to the tables, even though these functions will never be
629        called when UTF-8 support is disabled. Otherwise there are problems with a
630        shared library.
632    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
634        (a) It was defining its arguments as char * instead of void *.
636        (b) It was assuming that all moves were upwards in memory; this was true
637            a long time ago when I wrote it, but is no longer the case.
639        The emulated memove() is provided for those environments that have neither
640        memmove() nor bcopy(). I didn't think anyone used it these days, but that
641        is clearly not the case, as these two bugs were recently reported.
643    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
644        and Detrail to create the HTML documentation, the .txt form of the man
645        pages, and it removes trailing spaces from listed files. It also creates
646        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
647        case, it wraps all the #defines with #ifndefs. This script should be run
648        before "make dist".
650    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
651        with Unicode property support.
653        (a) For a maximizing quantifier, if the two different cases of the
654            character were of different lengths in their UTF-8 codings (there are
655            some cases like this - I found 11), and the matching function had to
656            back up over a mixture of the two cases, it incorrectly assumed they
657            were both the same length.
659        (b) When PCRE was configured to use the heap rather than the stack for
660            recursion during matching, it was not correctly preserving the data for
661            the other case of a UTF-8 character when checking ahead for a match
662            while processing a minimizing repeat. If the check also involved
663            matching a wide character, but failed, corruption could cause an
664            erroneous result when trying to check for a repeat of the original
665            character.
667    13. Some tidying changes to the testing mechanism:
669        (a) The RunTest script now detects the internal link size and whether there
670            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
671            values substituted by "configure". (The RunGrepTest script already did
672            this for UTF-8.) The configure.ac script no longer substitutes the
673            relevant variables.
675        (b) The debugging options /B and /D in pcretest show the compiled bytecode
676            with length and offset values. This means that the output is different
677            for different internal link sizes. Test 2 is skipped for link sizes
678            other than 2 because of this, bypassing the problem. Unfortunately,
679            there was also a test in test 3 (the locale tests) that used /B and
680            failed for link sizes other than 2. Rather than cut the whole test out,
681            I have added a new /Z option to pcretest that replaces the length and
682            offset values with spaces. This is now used to make test 3 independent
683            of link size. (Test 2 will be tidied up later.)
685    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
686        segmentation fault instead of returning the appropriate error message.
688    15. In multiline mode when the newline sequence was set to "any", the pattern
689        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
690        This doesn't seem right; it now treats the CRLF combination as the line
691        ending, and so does not match in that case. It's only a pattern such as ^$
692        that would hit this one: something like ^ABC$ would have failed after \r
693        and then tried again after \r\n.
695    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
696        in an attempt to make files that differ only in their line terminators
697        compare equal. This works on Linux.
699    17. Under certain error circumstances pcregrep might try to free random memory
700        as it exited. This is now fixed, thanks to valgrind.
702    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
703        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
704        was because its rules for how to advance for /g after matching an empty
705        string at the end of a line did not allow for this case. They now check for
706        it specially.
708    20. pcretest is supposed to handle patterns and data of any length, by
709        extending its buffers when necessary. It was getting this wrong when the
710        buffer for a data line had to be extended.
712    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
713        CRLF as a newline sequence.
715    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
716        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
717        I have nevertheless tidied it up.
719    23. Added some casts to kill warnings from HP-UX ia64 compiler.
721    24. Added a man page for pcre-config.
724    Version 7.0 19-Dec-06
725    ---------------------
727     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
728        moving to gcc 4.1.1.
730     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
731        sys/time.h, which is documented as needed for this function. It doesn't
732        seem to matter on Linux, but it showed up on some releases of OS X.
734     3. It seems that there are systems where bytes whose values are greater than
735        127 match isprint() in the "C" locale. The "C" locale should be the
736        default when a C program starts up. In most systems, only ASCII printing
737        characters match isprint(). This difference caused the output from pcretest
738        to vary, making some of the tests fail. I have changed pcretest so that:
740        (a) When it is outputting text in the compiled version of a pattern, bytes
741            other than 32-126 are always shown as hex escapes.
743        (b) When it is outputting text that is a matched part of a subject string,
744            it does the same, unless a different locale has been set for the match
745            (using the /L modifier). In this case, it uses isprint() to decide.
747     4. Fixed a major bug that caused incorrect computation of the amount of memory
748        required for a compiled pattern when options that changed within the
749        pattern affected the logic of the preliminary scan that determines the
750        length. The relevant options are -x, and -i in UTF-8 mode. The result was
751        that the computed length was too small. The symptoms of this bug were
752        either the PCRE error "internal error: code overflow" from pcre_compile(),
753        or a glibc crash with a message such as "pcretest: free(): invalid next
754        size (fast)". Examples of patterns that provoked this bug (shown in
755        pcretest format) are:
757          /(?-x: )/x
758          /(?x)(?-x: \s*#\s*)/
759          /((?i)[\x{c0}])/8
760          /(?i:[\x{c0}])/8
762        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
763        is now done differently.
765     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
766        wrapper classes; (b) implement a new function in the C++ scanner that is
767        more efficient than the old way of doing things because it avoids levels of
768        recursion in the regex matching; (c) add a paragraph to the documentation
769        for the FullMatch() function.
771     6. The escape sequence \n was being treated as whatever was defined as
772        "newline". Not only was this contrary to the documentation, which states
773        that \n is character 10 (hex 0A), but it also went horribly wrong when
774        "newline" was defined as CRLF. This has been fixed.
776     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
777        was being set to -1 for the "end of line" case (supposedly a value that no
778        character can have). Though this value is never used (the check for end of
779        line is "zero bytes in current character"), it caused compiler complaints.
780        I've changed it to 0xffffffff.
782     8. In pcre_version.c, the version string was being built by a sequence of
783        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
784        string (as it is for production releases) called a macro with an empty
785        argument. The C standard says the result of this is undefined. The gcc
786        compiler treats it as an empty string (which was what was wanted) but it is
787        reported that Visual C gives an error. The source has been hacked around to
788        avoid this problem.
790     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
791        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
792        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
793        of them did).
795    10. Originally, pcretest opened its input and output without "b"; then I was
796        told that "b" was needed in some environments, so it was added for release
797        5.0 to both the input and output. (It makes no difference on Unix-like
798        systems.) Later I was told that it is wrong for the input on Windows. I've
799        now abstracted the modes into two macros, to make it easier to fiddle with
800        them, and removed "b" from the input mode under Windows.
802    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
804    12. Added -help and --help to pcretest as an official way of being reminded
805        of the options.
807    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
808        and pcrecpp.cc because they annoy compilers at high warning levels.
810    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
812    15. Fixed an occurrence of == in configure.ac that should have been = (shell
813        scripts are not C programs :-) and which was not noticed because it works
814        on Linux.
816    16. pcretest is supposed to handle any length of pattern and data line (as one
817        line or as a continued sequence of lines) by extending its input buffer if
818        necessary. This feature was broken for very long pattern lines, leading to
819        a string of junk being passed to pcre_compile() if the pattern was longer
820        than about 50K.
822    17. I have done a major re-factoring of the way pcre_compile() computes the
823        amount of memory needed for a compiled pattern. Previously, there was code
824        that made a preliminary scan of the pattern in order to do this. That was
825        OK when PCRE was new, but as the facilities have expanded, it has become
826        harder and harder to keep it in step with the real compile phase, and there
827        have been a number of bugs (see for example, 4 above). I have now found a
828        cunning way of running the real compile function in a "fake" mode that
829        enables it to compute how much memory it would need, while actually only
830        ever using a few hundred bytes of working memory and without too many
831        tests of the mode. This should make future maintenance and development
832        easier. A side effect of this work is that the limit of 200 on the nesting
833        depth of parentheses has been removed (though this was never a serious
834        limitation, I suspect). However, there is a downside: pcre_compile() now
835        runs more slowly than before (30% or more, depending on the pattern). I
836        hope this isn't a big issue. There is no effect on runtime performance.
838    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
839        newline (only possible for the last line of a file) and it was a
840        pattern that set a locale (followed by /Lsomething), pcretest crashed.
842    19. Added additional timing features to pcretest. (1) The -tm option now times
843        matching only, not compiling. (2) Both -t and -tm can be followed, as a
844        separate command line item, by a number that specifies the number of
845        repeats to use when timing. The default is 50000; this gives better
846        precision, but takes uncomfortably long for very large patterns.
848    20. Extended pcre_study() to be more clever in cases where a branch of a
849        subpattern has no definite first character. For example, (a*|b*)[cd] would
850        previously give no result from pcre_study(). Now it recognizes that the
851        first character must be a, b, c, or d.
853    21. There was an incorrect error "recursive call could loop indefinitely" if
854        a subpattern (or the entire pattern) that was being tested for matching an
855        empty string contained only one non-empty item after a nested subpattern.
856        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
857        incorrectly, because the \d was being skipped in the check.
859    22. The pcretest program now has a new pattern option /B and a command line
860        option -b, which is equivalent to adding /B to every pattern. This causes
861        it to show the compiled bytecode, without the additional information that
862        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
863        is the same as /B/I).
865    23. A new optimization is now able automatically to treat some sequences such
866        as a*b as a*+b. More specifically, if something simple (such as a character
867        or a simple class like \d) has an unlimited quantifier, and is followed by
868        something that cannot possibly match the quantified thing, the quantifier
869        is automatically "possessified".
871    24. A recursive reference to a subpattern whose number was greater than 39
872        went wrong under certain circumstances in UTF-8 mode. This bug could also
873        have affected the operation of pcre_study().
875    25. Realized that a little bit of performance could be had by replacing
876        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
878    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
880    27. Possessive quantifiers such as a++ were previously implemented by turning
881        them into atomic groups such as ($>a+). Now they have their own opcodes,
882        which improves performance. This includes the automatically created ones
883        from 23 above.
885    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
886        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
887        the first matched character to be a colon. This applied both to named and
888        numbered groups.
890    29. The ucpinternal.h header file was missing its idempotency #ifdef.
892    30. I was sent a "project" file called libpcre.a.dev which I understand makes
893        building PCRE on Windows easier, so I have included it in the distribution.
895    31. There is now a check in pcretest against a ridiculously large number being
896        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
897        loop, the loop is abandoned.
899    32. Forward references to subpatterns in conditions such as (?(2)...) where
900        subpattern 2 is defined later cause pcre_compile() to search forwards in
901        the pattern for the relevant set of parentheses. This search went wrong
902        when there were unescaped parentheses in a character class, parentheses
903        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
905    33. "Subroutine" calls and backreferences were previously restricted to
906        referencing subpatterns earlier in the regex. This restriction has now
907        been removed.
909    34. Added a number of extra features that are going to be in Perl 5.10. On the
910        whole, these are just syntactic alternatives for features that PCRE had
911        previously implemented using the Python syntax or my own invention. The
912        other formats are all retained for compatibility.
914        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
915            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
916            also .NET compatible.
918        (b) A recursion or subroutine call to a named group can now be defined as
919            (?&name) as well as (?P>name).
921        (c) A backreference to a named group can now be defined as \k<name> or
922            \k'name' as well as (?P=name). The new forms, as well as being in Perl
923            5.10, are also .NET compatible.
925        (d) A conditional reference to a named group can now use the syntax
926            (?(<name>) or (?('name') as well as (?(name).
928        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
929            groups (named and numbered) that are never evaluated inline, but can be
930            called as "subroutines" from elsewhere. In effect, the DEFINE condition
931            is always false. There may be only one alternative in such a group.
933        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
934            as the simple (?(R). The condition is true only if the most recent
935            recursion is that of the given number or name. It does not search out
936            through the entire recursion stack.
938        (g) The escape \gN or \g{N} has been added, where N is a positive or
939            negative number, specifying an absolute or relative reference.
941    35. Tidied to get rid of some further signed/unsigned compiler warnings and
942        some "unreachable code" warnings.
944    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
945        things, this adds five new scripts.
947    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
948        There were also incompatibilities regarding the handling of \Q..\E inside
949        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
950        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
952    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
953        matches an empty string, and forcibly breaks the loop. There were bugs in
954        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
955        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
956        separate and independent bugs (that affected different cases) have been
957        fixed.
959    39. Refactored the code to abolish the use of different opcodes for small
960        capturing bracket numbers. This is a tidy that I avoided doing when I
961        removed the limit on the number of capturing brackets for 3.5 back in 2001.
962        The new approach is not only tidier, it makes it possible to reduce the
963        memory needed to fix the previous bug (38).
965    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
966        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
967        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
968        mode.
970    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
971        report.
973    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
974        copy construction and assignment in the C++ wrapper.
976    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
977        couple of bugs that could have given wrong results in the "--newline=crlf"
978        case.
980    44. Added a number of casts and did some reorganization of signed/unsigned int
981        variables following suggestions from Dair Grant. Also renamed the variable
982        "this" as "item" because it is a C++ keyword.
984    45. Arranged for dftables to add
986          #include "pcre_internal.h"
988        to pcre_chartables.c because without it, gcc 4.x may remove the array
989        definition from the final binary if PCRE is built into a static library and
990        dead code stripping is activated.
992    46. For an unanchored pattern, if a match attempt fails at the start of a
993        newline sequence, and the newline setting is CRLF or ANY, and the next two
994        characters are CRLF, advance by two characters instead of one.
997    Version 6.7 04-Jul-06
998    ---------------------
1000     1. In order to handle tests when input lines are enormously long, pcretest has
1001        been re-factored so that it automatically extends its buffers when
1002        necessary. The code is crude, but this _is_ just a test program. The
1003        default size has been increased from 32K to 50K.
1005     2. The code in pcre_study() was using the value of the re argument before
1006        testing it for NULL. (Of course, in any sensible call of the function, it
1007        won't be NULL.)
1009     3. The memmove() emulation function in pcre_internal.h, which is used on
1010        systems that lack both memmove() and bcopy() - that is, hardly ever -
1011        was missing a "static" storage class specifier.
1013     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1014        containing an extended class (one that cannot be represented by a bitmap
1015        because it contains high-valued characters or Unicode property items, e.g.
1016        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1017        pattern, but PCRE should not loop if you do not (it no longer does).
1018        [Detail: two cases were found: (a) a repeated subpattern containing an
1019        extended class; (b) a recursive reference to a subpattern that followed a
1020        previous extended class. It wasn't skipping over the extended class
1021        correctly when UTF-8 mode was not set.]
1023     5. A negated single-character class was not being recognized as fixed-length
1024        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1025        compile error "lookbehind assertion is not fixed length".
1027     6. The RunPerlTest auxiliary script was showing an unexpected difference
1028        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1029        write a Perl script that can interpret lines of an input file either as
1030        byte characters or as UTF-8, which is what "perltest" was being required to
1031        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1032        can't do is switch easily at run time between having the "use utf8;" pragma
1033        or not. In the end, I fudged it by using the RunPerlTest script to insert
1034        "use utf8;" explicitly for the UTF-8 tests.
1036     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1037        the end of the subject string, contrary to the documentation and to what
1038        Perl does. This was true of both matching functions. Now it matches only at
1039        the start of the subject and immediately after *internal* newlines.
1041     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1042        a pointer to an int instead of a pointer to an unsigned long int. This
1043        caused problems on 64-bit systems.
1045     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1046        instance of the 'standard' template library not being so standard".
1048    10. There was no check on the number of named subpatterns nor the maximum
1049        length of a subpattern name. The product of these values is used to compute
1050        the size of the memory block for a compiled pattern. By supplying a very
1051        long subpattern name and a large number of named subpatterns, the size
1052        computation could be caused to overflow. This is now prevented by limiting
1053        the length of names to 32 characters, and the number of named subpatterns
1054        to 10,000.
1056    11. Subpatterns that are repeated with specific counts have to be replicated in
1057        the compiled pattern. The size of memory for this was computed from the
1058        length of the subpattern and the repeat count. The latter is limited to
1059        65535, but there was no limit on the former, meaning that integer overflow
1060        could in principle occur. The compiled length of a repeated subpattern is
1061        now limited to 30,000 bytes in order to prevent this.
1063    12. Added the optional facility to have named substrings with the same name.
1065    13. Added the ability to use a named substring as a condition, using the
1066        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1067        are numbers (not recommended). Forward references are permitted.
1069    14. Added forward references in named backreferences (if you see what I mean).
1071    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1072        pattern could run off the end of the subject. For example, the pattern
1073        "(?s)(.{1,5})"8 did this with the subject "ab".
1075    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1076        PCRE_CASELESS was set when matching characters that were quantified with ?
1077        or *.
1079    17. A character class other than a single negated character that had a minimum
1080        but no maximum quantifier - for example [ab]{6,} - was not handled
1081        correctly by pce_dfa_exec(). It would match only one character.
1083    18. A valid (though odd) pattern that looked like a POSIX character
1084        class but used an invalid character after [ (for example [[,abc,]]) caused
1085        pcre_compile() to give the error "Failed: internal error: code overflow" or
1086        in some cases to crash with a glibc free() error. This could even happen if
1087        the pattern terminated after [[ but there just happened to be a sequence of
1088        letters, a binary zero, and a closing ] in the memory that followed.
1090    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1091        over the years. Originally (before any Unicode support), just the bottom 8
1092        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1093        output from "man perlunicode" includes this:
1095          The regular expression compiler produces polymorphic opcodes.  That
1096          is, the pattern adapts to the data and automatically switches to
1097          the Unicode character scheme when presented with Unicode data--or
1098          instead uses a traditional byte scheme when presented with byte
1099          data.
1101        Sadly, a wide octal escape does not cause a switch, and in a string with
1102        no other multibyte characters, these octal escapes are treated as before.
1103        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1104        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1105        Unicode string.
1107        I have not perpetrated such confusion in PCRE. Up till now, it took just
1108        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1109        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1110        translate to the appropriate multibyte character.
1112    29. Applied some refactoring to reduce the number of warnings from Microsoft
1113        and Borland compilers. This has included removing the fudge introduced
1114        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1115        a warning about an unused variable.
1117    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1118        characters since release 4.0, because Perl (from release 5.004) does not.
1119        [Or at least, is documented not to: some releases seem to be in conflict
1120        with the documentation.] However, when a pattern was studied with
1121        pcre_study() and all its branches started with \s, PCRE still included VT
1122        as a possible starting character. Of course, this did no harm; it just
1123        caused an unnecessary match attempt.
1125    22. Removed a now-redundant internal flag bit that recorded the fact that case
1126        dependency changed within the pattern. This was once needed for "required
1127        byte" processing, but is no longer used. This recovers a now-scarce options
1128        bit. Also moved the least significant internal flag bit to the most-
1129        significant bit of the word, which was not previously used (hangover from
1130        the days when it was an int rather than a uint) to free up another bit for
1131        the future.
1133    23. Added support for CRLF line endings as well as CR and LF. As well as the
1134        default being selectable at build time, it can now be changed at runtime
1135        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1136        specify that it is scanning data with non-default line endings.
1138    24. Changed the definition of CXXLINK to make it agree with the definition of
1139        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1141    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1142        recursions. This makes a big different to stack usage for some patterns.
1144    26. If a subpattern containing a named recursion or subroutine reference such
1145        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1146        the space required for the compiled pattern went wrong and gave too small a
1147        value. Depending on the environment, this could lead to "Failed: internal
1148        error: code overflow at offset 49" or "glibc detected double free or
1149        corruption" errors.
1151    27. Applied patches from Google (a) to support the new newline modes and (b) to
1152        advance over multibyte UTF-8 characters in GlobalReplace.
1154    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1155        difference for some implementation of PCRE in some Windows version.
1157    29. Added some extra testing facilities to pcretest:
1159        \q<number>   in a data line sets the "match limit" value
1160        \Q<number>   in a data line sets the "match recursion limt" value
1161        -S <number>  sets the stack size, where <number> is in megabytes
1163        The -S option isn't available for Windows.
1166    Version 6.6 06-Feb-06
1167    ---------------------
1169     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1170        in pcreposix.h. I have copied the definition from pcre.h.
1172     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1173        because pcre.h is no longer a built file.
1175     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1176        not normally included in the compiled code.
1179    Version 6.5 01-Feb-06
1180    ---------------------
1182     1. When using the partial match feature with pcre_dfa_exec(), it was not
1183        anchoring the second and subsequent partial matches at the new starting
1184        point. This could lead to incorrect results. For example, with the pattern
1185        /1234/, partially matching against "123" and then "a4" gave a match.
1187     2. Changes to pcregrep:
1189        (a) All non-match returns from pcre_exec() were being treated as failures
1190            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1191            error message is output. Some extra information is given for the
1192            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1193            probably the only errors that are likely to be caused by users (by
1194            specifying a regex that has nested indefinite repeats, for instance).
1195            If there are more than 20 of these errors, pcregrep is abandoned.
1197        (b) A binary zero was treated as data while matching, but terminated the
1198            output line if it was written out. This has been fixed: binary zeroes
1199            are now no different to any other data bytes.
1201        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1202            used to set a locale for matching. The --locale=xxxx long option has
1203            been added (no short equivalent) to specify a locale explicitly on the
1204            pcregrep command, overriding the environment variables.
1206        (d) When -B was used with -n, some line numbers in the output were one less
1207            than they should have been.
1209        (e) Added the -o (--only-matching) option.
1211        (f) If -A or -C was used with -c (count only), some lines of context were
1212            accidentally printed for the final match.
1214        (g) Added the -H (--with-filename) option.
1216        (h) The combination of options -rh failed to suppress file names for files
1217            that were found from directory arguments.
1219        (i) Added the -D (--devices) and -d (--directories) options.
1221        (j) Added the -F (--fixed-strings) option.
1223        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1225        (l) Added the --colo(u)r option.
1227        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1228            is not present by default.
1230     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1231        items such as (?R) or (?1), when the recursion could match a number of
1232        alternatives. If it matched one of the alternatives, but subsequently,
1233        outside the recursion, there was a failure, the code tried to back up into
1234        the recursion. However, because of the way PCRE is implemented, this is not
1235        possible, and the result was an incorrect result from the match.
1237        In order to prevent this happening, the specification of recursion has
1238        been changed so that all such subpatterns are automatically treated as
1239        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1241     4. I had overlooked the fact that, in some locales, there are characters for
1242        which isalpha() is true but neither isupper() nor islower() are true. In
1243        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1244        and ordfeminine) are like this. This affected the treatment of \w and \W
1245        when they appeared in character classes, but not when they appeared outside
1246        a character class. The bit map for "word" characters is now created
1247        separately from the results of isalnum() instead of just taking it from the
1248        upper, lower, and digit maps. (Plus the underscore character, of course.)
1250     5. The above bug also affected the handling of POSIX character classes such as
1251        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1252        permanent tables. Instead, the bit maps for such a class were previously
1253        created as the appropriate unions of the upper, lower, and digit bitmaps.
1254        Now they are created by subtraction from the [[:word:]] class, which has
1255        its own bitmap.
1257     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1258        It is created by subtracting the vertical space characters (\x09, \x0a,
1259        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1260        subtraction was done in the overall bitmap for a character class, meaning
1261        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1262        be recognized. This bug has been fixed.
1264     7. Patches from the folks at Google:
1266          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1267          real life, but is still worth protecting against".
1269          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1270          regular expressions".
1272          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1273          have it.
1275          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1276          "configure" and the latter not, in order to fix a problem somebody had
1277          with compiling the Arg class on HP-UX.
1279          (e) Improve the error-handling of the C++ wrapper a little bit.
1281          (f) New tests for checking recursion limiting.
1283     8. The pcre_memmove() function, which is used only if the environment does not
1284        have a standard memmove() function (and is therefore rarely compiled),
1285        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1286        returning a result (though PCRE never actually uses the result).
1288     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1289        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1290        returned instead of calling malloc() with an overflowing number that would
1291        most likely cause subsequent chaos.
1293    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1295    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1296        with this option is matched, the nmatch and pmatch options of regexec() are
1297        ignored.
1299    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1300        provided in case anyone wants to the the POSIX interface with UTF-8
1301        strings.
1303    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1304        C++ linking (needed for some HP-UX environments).
1306    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1307        (unused parameter) and in the pcre_printint() function (omitted "default"
1308        switch label when the default is to do nothing).
1310    15. Added some code to make it possible, when PCRE is compiled as a C++
1311        library, to replace subject pointers for pcre_exec() with a smart pointer
1312        class, thus making it possible to process discontinuous strings.
1314    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1315        much the same function. They were added by different people who were trying
1316        to make PCRE easy to compile on non-Unix systems. It has been suggested
1317        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1318        for compiling on Windows systems. I have therefore replaced it with
1319        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1320        defaults to "extern" for C or "extern C" for C++, which works fine on
1321        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1322        SCOPE with something explicit in config.h. In addition:
1324        (a) pcreposix.h still had just "extern" instead of either of these macros;
1325            I have replaced it with PCRE_DATA_SCOPE.
1327        (b) Functions such as _pcre_xclass(), which are internal to the library,
1328            but external in the C sense, all had PCRE_EXPORT in their definitions.
1329            This is apparently wrong for the Windows case, so I have removed it.
1330            (It makes no difference on Unix-like systems.)
1332    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1333        of recursive calls to match(). This is different to MATCH_LIMIT because
1334        that limits the total number of calls to match(), not all of which increase
1335        the depth of recursion. Limiting the recursion depth limits the amount of
1336        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1337        when PCRE is compiled, and changed at run time. A patch from Google adds
1338        this functionality to the C++ interface.
1340    18. Changes to the handling of Unicode character properties:
1342        (a) Updated the table to Unicode 4.1.0.
1344        (b) Recognize characters that are not in the table as "Cn" (undefined).
1346        (c) I revised the way the table is implemented to a much improved format
1347            which includes recognition of ranges. It now supports the ranges that
1348            are defined in UnicodeData.txt, and it also amalgamates other
1349            characters into ranges. This has reduced the number of entries in the
1350            table from around 16,000 to around 3,000, thus reducing its size
1351            considerably. I realized I did not need to use a tree structure after
1352            all - a binary chop search is just as efficient. Having reduced the
1353            number of entries, I extended their size from 6 bytes to 8 bytes to
1354            allow for more data.
1356        (d) Added support for Unicode script names via properties such as \p{Han}.
1358    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1359        matching that character.
1361    20. When matching a repeated Unicode property with a minimum greater than zero,
1362        (for example \pL{2,}), PCRE could look past the end of the subject if it
1363        reached it while seeking the minimum number of characters. This could
1364        happen only if some of the characters were more than one byte long, because
1365        there is a check for at least the minimum number of bytes.
1367    21. Refactored the implementation of \p and \P so as to be more general, to
1368        allow for more different types of property in future. This has changed the
1369        compiled form incompatibly. Anybody with saved compiled patterns that use
1370        \p or \P will have to recompile them.
1372    22. Added "Any" and "L&" to the supported property types.
1374    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1375        but give a compile time error if the value is greater than 0xff.
1377    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1378        accidentally not being installed or uninstalled.
1380    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1381        made were to insert the current release number. This seemed silly, because
1382        it made things harder for people building PCRE on systems that don't run
1383        "configure". I have turned pcre.h into a distributed file, no longer built
1384        by "configure", with the version identification directly included. There is
1385        no longer a pcre.h.in file.
1387        However, this change necessitated a change to the pcre-config script as
1388        well. It is built from pcre-config.in, and one of the substitutions was the
1389        release number. I have updated configure.ac so that ./configure now finds
1390        the release number by grepping pcre.h.
1392    26. Added the ability to run the tests under valgrind.
1395    Version 6.4 05-Sep-05
1396    ---------------------
1398     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1399        "--" to be printed when multiple files were scanned, even when none of the
1400        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1401        consider it to be a bug, and have restored the previous behaviour.
1403     2. A couple of code tidies to get rid of compiler warnings.
1405     3. The pcretest program used to cheat by referring to symbols in the library
1406        whose names begin with _pcre_. These are internal symbols that are not
1407        really supposed to be visible externally, and in some environments it is
1408        possible to suppress them. The cheating is now confined to including
1409        certain files from the library's source, which is a bit cleaner.
1411     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1412        file's purpose clearer.
1414     5. Reorganized pcre_ucp_findchar().
1417    Version 6.3 15-Aug-05
1418    ---------------------
1420     1. The file libpcre.pc.in did not have general read permission in the tarball.
1422     2. There were some problems when building without C++ support:
1424        (a) If C++ support was not built, "make install" and "make test" still
1425            tried to test it.
1427        (b) There were problems when the value of CXX was explicitly set. Some
1428            changes have been made to try to fix these, and ...
1430        (c) --disable-cpp can now be used to explicitly disable C++ support.
1432        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1433            backslash in a target when C++ was disabled. This confuses some
1434            versions of "make", apparently. Using an intermediate variable solves
1435            this. (Same for CPP_LOBJ.)
1437     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1438        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1439        necessary on certain architectures.
1441     4. Added a setting of -export-symbols-regex to the link command to remove
1442        those symbols that are exported in the C sense, but actually are local
1443        within the library, and not documented. Their names all begin with
1444        "_pcre_". This is not a perfect job, because (a) we have to except some
1445        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1446        available (and never for static libraries). I have made a note to try to
1447        find a way round (a) in the future.
1450    Version 6.2 01-Aug-05
1451    ---------------------
1453     1. There was no test for integer overflow of quantifier values. A construction
1454        such as {1111111111111111} would give undefined results. What is worse, if
1455        a minimum quantifier for a parenthesized subpattern overflowed and became
1456        negative, the calculation of the memory size went wrong. This could have
1457        led to memory overwriting.
1459     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1461     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1462        operating environments where this matters.
1464     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1465        PCRE options from within the C++ wrapper.
1467     5. Named capturing subpatterns were not being correctly counted when a pattern
1468        was compiled. This caused two problems: (a) If there were more than 100
1469        such subpatterns, the calculation of the memory needed for the whole
1470        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1471        back references of the form \12, where the number was greater than 9, were
1472        not recognized as back references, even though there were sufficient
1473        previous subpatterns.
1475     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1476        versions of gcc, e.g. 2.95.4.
1479    Version 6.1 21-Jun-05
1480    ---------------------
1482     1. There was one reference to the variable "posix" in pcretest.c that was not
1483        surrounded by "#if !defined NOPOSIX".
1485     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1486        the cross-check on the old pcre_info() function, for the benefit of the
1487        cut-down version of PCRE that is currently imported into Exim.
1489     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1490        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1491        patterns that start (?i) but I don't think that matters. The use of (?i) is
1492        just an example; this all applies to the other options as well.
1494     4. Since libtool seems to echo the compile commands it is issuing, the output
1495        from "make" can be reduced a bit by putting "@" in front of each libtool
1496        compile command.
1498     5. Patch from the folks at Google for configure.in to be a bit more thorough
1499        in checking for a suitable C++ installation before trying to compile the
1500        C++ stuff. This should fix a reported problem when a compiler was present,
1501        but no suitable headers.
1503     6. The man pages all had just "PCRE" as their title. I have changed them to
1504        be the relevant file name. I have also arranged that these names are
1505        retained in the file doc/pcre.txt, which is a concatenation in text format
1506        of all the man pages except the little individual ones for each function.
1508     7. The NON-UNIX-USE file had not been updated for the different set of source
1509        files that come with release 6. I also added a few comments about the C++
1510        wrapper.
1513    Version 6.0 07-Jun-05
1514    ---------------------
1516     1. Some minor internal re-organization to help with my DFA experiments.
1518     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1519        didn't matter for the library itself when fully configured, but did matter
1520        when compiling without UCP support, or within Exim, where the ucp files are
1521        not imported.
1523     3. Refactoring of the library code to split up the various functions into
1524        different source modules. The addition of the new DFA matching code (see
1525        below) to a single monolithic source would have made it really too
1526        unwieldy, quite apart from causing all the code to be include in a
1527        statically linked application, when only some functions are used. This is
1528        relevant even without the DFA addition now that patterns can be compiled in
1529        one application and matched in another.
1531        The downside of splitting up is that there have to be some external
1532        functions and data tables that are used internally in different modules of
1533        the library but which are not part of the API. These have all had their
1534        names changed to start with "_pcre_" so that they are unlikely to clash
1535        with other external names.
1537     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1538        a different (DFA) algorithm. Although it is slower than the original
1539        function, it does have some advantages for certain types of matching
1540        problem.
1542     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1543        including restarting after a partial match.
1545     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1546        defined when compiling for Windows was sent to me. I have put it into the
1547        code, though I have no means of testing or verifying it.
1549     7. Added the pcre_refcount() auxiliary function.
1551     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1552        match before or at the first newline in the subject string. In pcretest,
1553        the /f option on a pattern can be used to set this.
1555     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1556        would behave wrongly. This has been present in PCRE since release 4.0.
1558    10. A number of changes to the pcregrep command:
1560        (a) Refactored how -x works; insert ^(...)$ instead of setting
1561            PCRE_ANCHORED and checking the length, in preparation for adding
1562            something similar for -w.
1564        (b) Added the -w (match as a word) option.
1566        (c) Refactored the way lines are read and buffered so as to have more
1567            than one at a time available.
1569        (d) Implemented a pcregrep test script.
1571        (e) Added the -M (multiline match) option. This allows patterns to match
1572            over several lines of the subject. The buffering ensures that at least
1573            8K, or the rest of the document (whichever is the shorter) is available
1574            for matching (and similarly the previous 8K for lookbehind assertions).
1576        (f) Changed the --help output so that it now says
1578              -w, --word-regex(p)
1580            instead of two lines, one with "regex" and the other with "regexp"
1581            because that confused at least one person since the short forms are the
1582            same. (This required a bit of code, as the output is generated
1583            automatically from a table. It wasn't just a text change.)
1585        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1586            option but starts with a hyphen. Could be a pattern or a path name
1587            starting with a hyphen, for instance.
1589        (h) "-" can be given as a file name to represent stdin.
1591        (i) When file names are being printed, "(standard input)" is used for
1592            the standard input, for compatibility with GNU grep. Previously
1593            "<stdin>" was used.
1595        (j) The option --label=xxx can be used to supply a name to be used for
1596            stdin when file names are being printed. There is no short form.
1598        (k) Re-factored the options decoding logic because we are going to add
1599            two more options that take data. Such options can now be given in four
1600            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1602        (l) Added the -A, -B, and -C options for requesting that lines of context
1603            around matches be printed.
1605        (m) Added the -L option to print the names of files that do not contain
1606            any matching lines, that is, the complement of -l.
1608        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1609            continue to scan other files.
1611        (o) The -s option was incorrectly implemented. For compatibility with other
1612            greps, it now suppresses the error message for a non-existent or non-
1613            accessible file (but not the return code). There is a new option called
1614            -q that suppresses the output of matching lines, which was what -s was
1615            previously doing.
1617        (p) Added --include and --exclude options to specify files for inclusion
1618            and exclusion when recursing.
1620    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1621        Hopefully, it now does.
1623    12. Missing cast in pcre_study().
1625    13. Added an "uninstall" target to the makefile.
1627    14. Replaced "extern" in the function prototypes in Makefile.in with
1628        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1629        world, but is set differently for Windows.
1631    15. Added a second compiling function called pcre_compile2(). The only
1632        difference is that it has an extra argument, which is a pointer to an
1633        integer error code. When there is a compile-time failure, this is set
1634        non-zero, in addition to the error test pointer being set to point to an
1635        error message. The new argument may be NULL if no error number is required
1636        (but then you may as well call pcre_compile(), which is now just a
1637        wrapper). This facility is provided because some applications need a
1638        numeric error indication, but it has also enabled me to tidy up the way
1639        compile-time errors are handled in the POSIX wrapper.
1641    16. Added VPATH=.libs to the makefile; this should help when building with one
1642        prefix path and installing with another. (Or so I'm told by someone who
1643        knows more about this stuff than I do.)
1645    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1646        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1647        match everything, including newlines. This is not POSIX-compatible, but
1648        somebody wanted the feature. From pcretest it can be activated by using
1649        both the P and the s flags.
1651    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1653    19. libpcre.pc was being incorrectly installed as executable.
1655    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1656        it now also looks for '\r' so that it will work unmodified on Windows.
1658    21. Added Google's contributed C++ wrapper to the distribution.
1660    22. Added some untidy missing memory free() calls in pcretest, to keep
1661        Electric Fence happy when testing.
1665    Version 5.0 13-Sep-04
1666    ---------------------
1668     1. Internal change: literal characters are no longer packed up into items
1669        containing multiple characters in a single byte-string. Each character
1670        is now matched using a separate opcode. However, there may be more than one
1671        byte in the character in UTF-8 mode.
1673     2. The pcre_callout_block structure has two new fields: pattern_position and
1674        next_item_length. These contain the offset in the pattern to the next match
1675        item, and its length, respectively.
1677     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1678        insertion of callouts before each pattern item. Added the /C option to
1679        pcretest to make use of this.
1681     4. On the advice of a Windows user, the lines
1683          #if defined(_WIN32) || defined(WIN32)
1684          _setmode( _fileno( stdout ), 0x8000 );
1685          #endif  /* defined(_WIN32) || defined(WIN32) */
1687        have been added to the source of pcretest. This apparently does useful
1688        magic in relation to line terminators.
1690     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1691        for the benefit of those environments where the "b" makes a difference.
1693     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1694        to know about it. I have put a hack into configure.in that adds in code
1695        to set GCC=yes if CC=icc. This seems to end up at a point in the
1696        generated configure script that is early enough to affect the setting of
1697        compiler options, which is what is needed, but I have no means of testing
1698        whether it really works. (The user who reported this had patched the
1699        generated configure script, which of course I cannot do.)
1701        LATER: After change 22 below (new libtool files), the configure script
1702        seems to know about icc (and also ecc). Therefore, I have commented out
1703        this hack in configure.in.
1705     7. Added support for pkg-config (2 patches were sent in).
1707     8. Negated POSIX character classes that used a combination of internal tables
1708        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1709        [[:^ascii]]. Typically, they would match almost any characters. The other
1710        POSIX classes were not broken in this way.
1712     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1713        to find the match, as PCRE was deluded into thinking that the match had to
1714        start at the start point or following a newline. The same bug applied to
1715        patterns with negative forward assertions or any backward assertions
1716        preceding ".*" at the start, unless the pattern required a fixed first
1717        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1719    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1720        starting at the last subject character, bytes beyond the end of the subject
1721        string were read.
1723    11. Renamed the variable "class" as "classbits" to make life easier for C++
1724        users. (Previously there was a macro definition, but it apparently wasn't
1725        enough.)
1727    12. Added the new field "tables" to the extra data so that tables can be passed
1728        in at exec time, or the internal tables can be re-selected. This allows
1729        a compiled regex to be saved and re-used at a later time by a different
1730        program that might have everything at different addresses.
1732    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1733        -R library as well as a -L library.
1735    14. The debugging options of pcretest (-d on the command line or D on a
1736        pattern) showed incorrect output for anything following an extended class
1737        that contained multibyte characters and which was followed by a quantifier.
1739    15. Added optional support for general category Unicode character properties
1740        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1741        support. It adds about 90K to the size of the library. The meanings of the
1742        inbuilt class escapes such as \d and \s have NOT been changed.
1744    16. Updated pcredemo.c to include calls to free() to release the memory for the
1745        compiled pattern.
1747    17. The generated file chartables.c was being created in the source directory
1748        instead of in the building directory. This caused the build to fail if the
1749        source directory was different from the building directory, and was
1750        read-only.
1752    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1753        file. No doubt somebody will tell me if they don't make sense... Also added
1754        Dan Mooney's comments about building on OpenVMS.
1756    19. Added support for partial matching via the PCRE_PARTIAL option for
1757        pcre_exec() and the \P data escape in pcretest.
1759    20. Extended pcretest with 3 new pattern features:
1761        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1762              write the compiled pattern to the file whose name is "rest-of-line".
1763              This is a straight binary dump of the data, with the saved pointer to
1764              the character tables forced to be NULL. The study data, if any, is
1765              written too. After writing, pcretest reads a new pattern.
1767        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1768              compiled pattern from the given file. There must not be any
1769              occurrences of "<" in the file name (pretty unlikely); if there are,
1770              pcretest will instead treat the initial "<" as a pattern delimiter.
1771              After reading in the pattern, pcretest goes on to read data lines as
1772              usual.
1774        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1775              and 16-bit fields in a compiled pattern, to simulate a pattern that
1776              was compiled on a host of opposite endianness.
1778    21. The pcre-exec() function can now cope with patterns that were compiled on
1779        hosts of opposite endianness, with this restriction:
1781          As for any compiled expression that is saved and used later, the tables
1782          pointer field cannot be preserved; the extra_data field in the arguments
1783          to pcre_exec() should be used to pass in a tables address if a value
1784          other than the default internal tables were used at compile time.
1786    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1787        now diagnosed as an error. Previously, most of the time, a negative number
1788        would have been treated as zero, but if in addition "ovector" was passed as
1789        NULL, a crash could occur.
1791    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1792        new versions from the libtool 1.5 distribution (the last one is a copy of
1793        a file called libtool.m4). This seems to have fixed the need to patch
1794        "configure" to support Darwin 1.3 (which I used to do). However, I still
1795        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1796        workstation).
1798    24. Changed the PCRE licence to be the more standard "BSD" licence.
1801    Version 4.5 01-Dec-03
1802    ---------------------
1804     1. There has been some re-arrangement of the code for the match() function so
1805        that it can be compiled in a version that does not call itself recursively.
1806        Instead, it keeps those local variables that need separate instances for
1807        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1808        needs to "recurse". Keeping track of where control must go is done by means
1809        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1810        hide most of the details from the main code, and operates only if
1811        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1812        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1813        operating.
1815        To make it easier for callers to provide specially tailored get/free
1816        functions for this usage, two new functions, pcre_stack_malloc, and
1817        pcre_stack_free, are used. They are always called in strict stacking order,
1818        and the size of block requested is always the same.
1820        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1821        PCRE has been compiled to use the stack or the heap for recursion. The
1822        -C option of pcretest uses this to show which version is compiled.
1824        A new data escape \S, is added to pcretest; it causes the amounts of store
1825        obtained and freed by both kinds of malloc/free at match time to be added
1826        to the output.
1828     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1829        what's available on my current Linux desktop machine.
1831     3. When matching a UTF-8 string, the test for a valid string at the start has
1832        been extended. If start_offset is not zero, PCRE now checks that it points
1833        to a byte that is the start of a UTF-8 character. If not, it returns
1834        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1835        this is necessary because there may be backward assertions in the pattern.
1836        When matching the same subject several times, it may save resources to use
1837        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1839     4. The code for checking the validity of UTF-8 strings has been tightened so
1840        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1841        containing "overlong sequences".
1843     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1844        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1845        should have been "&", but it just so happened that all the cases this let
1846        through by mistake were picked up later in the function.
1848     6. I had used a variable called "isblank" - this is a C99 function, causing
1849        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1851     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1852        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1853        so the version is shown; (c) stop "make test" echoing "./RunTest".
1855     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1857     9. The prototype for memmove() for systems that don't have it was using
1858        size_t, but the inclusion of the header that defines size_t was later. I've
1859        moved the #includes for the C headers earlier to avoid this.
1861    10. Added some adjustments to the code to make it easier to compiler on certain
1862        special systems:
1864          (a) Some "const" qualifiers were missing.
1865          (b) Added the macro EXPORT before all exported functions; by default this
1866              is defined to be empty.
1867          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1868              that it reads its output file name as an argument instead of writing
1869              to the standard output and assuming this can be redirected.
1871    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1872        class containing characters with values greater than 255, PCRE compilation
1873        went into a loop.
1875    12. A recursive reference to a subpattern that was within another subpattern
1876        that had a minimum quantifier of zero caused PCRE to crash. For example,
1877        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1878        recursion. If the recursively-called subpattern itself had a zero repeat,
1879        that was OK.
1881    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1882        buffer into which it was copied (for escape processing) was still set at
1883        1024, so long lines caused crashes.
1885    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1886        "internal error: code overflow...". This applied to any character class
1887        that was followed by a possessive quantifier.
1889    15. Modified the Makefile to add libpcre.la as a prerequisite for
1890        libpcreposix.la because I was told this is needed for a parallel build to
1891        work.
1893    16. If a pattern that contained .* following optional items at the start was
1894        studied, the wrong optimizing data was generated, leading to matching
1895        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1896        matching string must start with a or b or c. The correct conclusion for
1897        this pattern is that a match can start with any character.
1900    Version 4.4 13-Aug-03
1901    ---------------------
1903     1. In UTF-8 mode, a character class containing characters with values between
1904        127 and 255 was not handled correctly if the compiled pattern was studied.
1905        In fixing this, I have also improved the studying algorithm for such
1906        classes (slightly).
1908     2. Three internal functions had redundant arguments passed to them. Removal
1909        might give a very teeny performance improvement.
1911     3. Documentation bug: the value of the capture_top field in a callout is *one
1912        more than* the number of the hightest numbered captured substring.
1914     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1915        in incorrectly linking with a previously installed version. They now link
1916        explicitly with libpcre.la.
1918     5. configure.in no longer needs to recognize Cygwin specially.
1920     6. A problem in pcre.in for Windows platforms is fixed.
1922     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1923        pcretest, it used to include the size of the study block as part of its
1924        output. Unfortunately, the structure contains a field that has a different
1925        size on different hardware architectures. This meant that the tests that
1926        showed this size failed. As the block is currently always of a fixed size,
1927        this information isn't actually particularly useful in pcretest output, so
1928        I have just removed it.
1930     8. Three pre-processor statements accidentally did not start in column 1.
1931        Sadly, there are *still* compilers around that complain, even though
1932        standard C has not required this for well over a decade. Sigh.
1934     9. In pcretest, the code for checking callouts passed small integers in the
1935        callout_data field, which is a void * field. However, some picky compilers
1936        complained about the casts involved for this on 64-bit systems. Now
1937        pcretest passes the address of the small integer instead, which should get
1938        rid of the warnings.
1940    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1941        both compile and run time, and gives an error if an invalid UTF-8 sequence
1942        is found. There is a option for disabling this check in cases where the
1943        string is known to be correct and/or the maximum performance is wanted.
1945    11. In response to a bug report, I changed one line in Makefile.in from
1947            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1948        to
1949            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1951        to look similar to other lines, but I have no way of telling whether this
1952        is the right thing to do, as I do not use Windows. No doubt I'll get told
1953        if it's wrong...
1956    Version 4.3 21-May-03
1957    ---------------------
1959    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1960       Makefile.
1962    2. Some refactoring to improve the quality of the code:
1964       (i)   The utf8_table... variables are now declared "const".
1966       (ii)  The code for \cx, which used the "case flipping" table to upper case
1967             lower case letters, now just substracts 32. This is ASCII-specific,
1968             but the whole concept of \cx is ASCII-specific, so it seems
1969             reasonable.
1971       (iii) PCRE was using its character types table to recognize decimal and
1972             hexadecimal digits in the pattern. This is silly, because it handles
1973             only 0-9, a-f, and A-F, but the character types table is locale-
1974             specific, which means strange things might happen. A private
1975             table is now used for this - though it costs 256 bytes, a table is
1976             much faster than multiple explicit tests. Of course, the standard
1977             character types table is still used for matching digits in subject
1978             strings against \d.
1980       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1981             ending in _t are). So I've renamed it as ESC_tee.
1983    3. The first argument for regexec() in the POSIX wrapper should have been
1984       defined as "const".
1986    4. Changed pcretest to use malloc() for its buffers so that they can be
1987       Electric Fenced for debugging.
1989    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1990       to read one or more bytes before the start of the subject string. Often this
1991       had no effect on PCRE's behaviour, but in some circumstances it could
1992       provoke a segmentation fault.
1994    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1995       to try to read one or more bytes before the start of the subject string.
1997    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1998       UTF-8 support could misbehave in various ways if the subject string
1999       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2000       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2001       back over UTF-8 characters.)
2004    Version 4.2 14-Apr-03
2005    ---------------------
2007    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2009    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2010         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2011         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2012         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2013         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2014           and BUILD_EXEEXT
2015         Note: automatic setting of the BUILD variables is not yet working
2016         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2017           compile-time but not at link-time
2018         [LINK]: use for linking executables only
2019         make different versions for Windows and non-Windows
2020         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2021           libraries
2022         [LINK_FOR_BUILD]: new variable
2023         [OBJEXT]: use throughout
2024         [EXEEXT]: use throughout
2025         <winshared>: new target
2026         <wininstall>: new target
2027         <dftables.o>: use native compiler
2028         <dftables>: use native linker
2029         <install>: handle Windows platform correctly
2030         <clean>: ditto
2031         <check>: ditto
2032         copy DLL to top builddir before testing
2034       As part of these changes, -no-undefined was removed again. This was reported
2035       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2036       in any case.
2038    3. Some tidies to get rid of compiler warnings:
2040       . In the match_data structure, match_limit was an unsigned long int, whereas
2041         match_call_count was an int. I've made them both unsigned long ints.
2043       . In pcretest the fact that a const uschar * doesn't automatically cast to
2044         a void * provoked a warning.
2046       . Turning on some more compiler warnings threw up some "shadow" variables
2047         and a few more missing casts.
2049    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2050       option, a class that contained a single character with a value between 128
2051       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2053    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2054       option, a class that contained several characters, but with at least one
2055       whose value was between 128 and 255 caused PCRE to crash.
2058    Version 4.1 12-Mar-03
2059    ---------------------
2061    1. Compiling with gcc -pedantic found a couple of places where casts were
2062    needed, and a string in dftables.c that was longer than standard compilers are
2063    required to support.
2065    2. Compiling with Sun's compiler found a few more places where the code could
2066    be tidied up in order to avoid warnings.
2068    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2069    first of these names is deprecated in the latest Autoconf in favour of the name
2070    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2071    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2072    analogy I have changed it to CFLAGS_FOR_BUILD.
2074    4. Added -no-undefined to the linking command in the Makefile, because this is
2075    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2076    linking step for the pcreposix library.
2078    5. PCRE was failing to diagnose the case of two named groups with the same
2079    name.
2081    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2082    literal character that is needed in the subject for a match, and scans along to
2083    ensure that it is present before embarking on the full matching process. This
2084    saves time in cases of nested unlimited repeats that are never going to match.
2085    Problem: the scan can take a lot of time if the subject is very long (e.g.
2086    megabytes), thus penalizing straightforward matches. It is now done only if the
2087    amount of subject to be scanned is less than 1000 bytes.
2089    7. A lesser problem with the same optimization is that it was recording the
2090    first character of an anchored pattern as "needed", thus provoking a search
2091    right along the subject, even when the first match of the pattern was going to
2092    fail. The "needed" character is now not set for anchored patterns, unless it
2093    follows something in the pattern that is of non-fixed length. Thus, it still
2094    fulfils its original purpose of finding quick non-matches in cases of nested
2095    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2098    Version 4.0 17-Feb-03
2099    ---------------------
2101    1. If a comment in an extended regex that started immediately after a meta-item
2102    extended to the end of string, PCRE compiled incorrect data. This could lead to
2103    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2105    2. Moved to autoconf 2.53 and libtool 1.4.2.
2107    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2108    the special perltest8 script is no longer needed - all the tests can be run
2109    from a single perltest script.
2111    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2112    by \s. It has now been removed in PCRE. This means it isn't recognized as
2113    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2114    class [:space:] *does* include VT, thereby creating a mess.
2116    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2117    space and tab.
2119    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2120    its new features into the main test script, reducing the number of scripts.
2122    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2123    were backward compatible, and made the (?i) apply to the whole pattern, as if
2124    /i were given. Now it behaves more logically, and applies the option setting
2125    only to what follows. PCRE has been changed to follow suit. However, if it
2126    finds options settings right at the start of the pattern, it extracts them into
2127    the global options, as before. Thus, they show up in the info data.
2129    8. Added support for the \Q...\E escape sequence. Characters in between are
2130    treated as literals. This is slightly different from Perl in that $ and @ are
2131    also handled as literals inside the quotes. In Perl, they will cause variable
2132    interpolation. Note the following examples:
2134        Pattern            PCRE matches      Perl matches
2136        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2137        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2138        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2140    For compatibility with Perl, \Q...\E sequences are recognized inside character
2141    classes as well as outside them.
2143    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2144    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2145    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2146    signed/unsigned warnings.
2148    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2149    option for pcretest, so I've replaced it by a simple function that does just
2150    that job.
2152    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2153    "pcregrep -".
2155    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2156    Java package. This provides some syntactic sugar for simple cases of what my
2157    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2158    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2159    item, you can use this simplified notation. Note that only makes sense with
2160    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2161    greediness, whatever the setting of the PCRE_UNGREEDY option.
2163    13. A change of greediness default within a pattern was not taking effect at
2164    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2165    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2166    was abstracted outside.
2168    14. PCRE now supports the \G assertion. It is true when the current matching
2169    position is at the start point of the match. This differs from \A when the
2170    starting offset is non-zero. Used with the /g option of pcretest (or similar
2171    code), it works in the same way as it does for Perl's /g option. If all
2172    alternatives of a regex begin with \G, the expression is anchored to the start
2173    match position, and the "anchored" flag is set in the compiled expression.
2175    15. Some bugs concerning the handling of certain option changes within patterns
2176    have been fixed. These applied to options other than (?ims). For example,
2177    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2178    been the other way round. Some of this was related to change 7 above.
2180    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2181    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2182    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2183    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2185    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2186    mode. Unlike ".", it always matches newline, whatever the setting of
2187    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2188    assertions. Perl allows it, but it doesn't (in general) work because it can't
2189    calculate the length of the lookbehind. At least, that's the case for Perl
2190    5.8.0 - I've been told they are going to document that it doesn't work in
2191    future.
2193    18. Added an error diagnosis for escapes that PCRE does not support: these are
2194    \L, \l, \N, \P, \p, \U, \u, and \X.
2196    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2197    reading past the end of the pattern in cases such as /[abcd/.
2199    20. PCRE was getting more memory than necessary for patterns with classes that
2200    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2202    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2203    compiling PCRE for use with Virtual Pascal.
2205    22. Small fix to the Makefile to make it work properly if the build is done
2206    outside the source tree.
2208    23. Added a new extension: a condition to go with recursion. If a conditional
2209    subpattern starts with (?(R) the "true" branch is used if recursion has
2210    happened, whereas the "false" branch is used only at the top level.
2212    24. When there was a very long string of literal characters (over 255 bytes
2213    without UTF support, over 250 bytes with UTF support), the computation of how
2214    much memory was required could be incorrect, leading to segfaults or other
2215    strange effects.
2217    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2218    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2219    there was a subsequent back reference to those brackets. This meant that, for
2220    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2221    possible to check for precisely this case. All we can do is abandon the
2222    optimization if .* occurs inside capturing brackets when there are any back
2223    references whatsoever. (See below for a better fix that came later.)
2225    26. The handling of the optimization for finding the first character of a
2226    non-anchored pattern, and for finding a character that is required later in the
2227    match were failing in some cases. This didn't break the matching; it just
2228    failed to optimize when it could. The way this is done has been re-implemented.
2230    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2232    28. Added a new feature that provides some of the functionality that Perl
2233    provides with (?{...}). The facility is termed a "callout". The way it is done
2234    in PCRE is for the caller to provide an optional function, by setting
2235    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2236    global variable. By default it is unset, which disables all calling out. To get
2237    the function called, the regex must include (?C) at appropriate points. This
2238    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2239    This provides a means of identifying different callout points. When PCRE
2240    reaches such a point in the regex, if pcre_callout has been set, the external
2241    function is called. It is provided with data in a structure called
2242    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2243    matching continues; if it returns a non-zero value, the match at the current
2244    point fails. However, backtracking will occur if possible. [This was changed
2245    later and other features added - see item 49 below.]
2247    29. pcretest is upgraded to test the callout functionality. It provides a
2248    callout function that displays information. By default, it shows the start of
2249    the match and the current position in the text. There are some new data escapes
2250    to vary what happens:
2252        \C+         in addition, show current contents of captured substrings
2253        \C-         do not supply a callout function
2254        \C!n        return 1 when callout number n is reached
2255        \C!n!m      return 1 when callout number n is reached for the mth time
2257    30. If pcregrep was called with the -l option and just a single file name, it
2258    output "<stdin>" if a match was found, instead of the file name.
2260    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2261    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2262    pcre_exec(). This saves a malloc/free per call. The default value of
2263    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2264    when configuring.
2266    32. The default maximum size of a compiled pattern is 64K. There have been a
2267    few cases of people hitting this limit. The code now uses macros to handle the
2268    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2269    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2270    configuring. Tests 2 and 5 work only with 2-byte links because they output
2271    debugging information about compiled patterns.
2273    33. Internal code re-arrangements:
2275    (a) Moved the debugging function for printing out a compiled regex into
2276        its own source file (printint.c) and used #include to pull it into
2277        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2278        separate copies.
2280    (b) Defined the list of op-code names for debugging as a macro in
2281        internal.h so that it is next to the definition of the opcodes.
2283    (c) Defined a table of op-code lengths for simpler skipping along compiled
2284        code. This is again a macro in internal.h so that it is next to the
2285        definition of the opcodes.
2287    34. Added support for recursive calls to individual subpatterns, along the
2288    lines of Robin Houston's patch (but implemented somewhat differently).
2290    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2291    allow it to read and process whole directories in Win32. This code was
2292    contributed by Lionel Fourquaux; it has not been tested by me.
2294    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2295    used to name a group. Names consist of alphanumerics and underscores, and must
2296    be unique. Back references use the syntax (?P=name) and recursive calls use
2297    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2298    numbers. The function pcre_fullinfo() can be used after compilation to extract
2299    a name/number map. There are three relevant calls:
2301      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2302      PCRE_INFO_NAMECOUNT            yields the number of entries
2303      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2305    The map is a vector of fixed-size entries. The size of each entry depends on
2306    the length of the longest name used. The first two bytes of each entry are the
2307    group number, most significant byte first. There follows the corresponding
2308    name, zero terminated. The names are in alphabetical order.
2310    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2311    case instead of 255. Making it the same both with and without UTF-8 support
2312    means that the same test output works with both.
2314    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2315    calling malloc() with a zero argument.
2317    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2318    optimization. I've improved things by keeping a bitmap of backreferences with
2319    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2320    fact referenced, the optimization can be applied. It is unlikely that a
2321    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2322    the match to follow \n) will appear inside brackets with a number greater than
2323    31, but if it does, any back reference > 31 suppresses the optimization.
2325    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2326    of disabling numbered capturing parentheses. Any opening parenthesis that is
2327    not followed by ? behaves as if it were followed by ?: but named parentheses
2328    can still be used for capturing (and they will acquire numbers in the usual
2329    way).
2331    41. Redesigned the return codes from the match() function into yes/no/error so
2332    that errors can be passed back from deep inside the nested calls. A malloc
2333    failure while inside a recursive subpattern call now causes the
2334    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2336    42. It is now possible to set a limit on the number of times the match()
2337    function is called in a call to pcre_exec(). This facility makes it possible to
2338    limit the amount of recursion and backtracking, though not in a directly
2339    obvious way, because the match() function is used in a number of different
2340    circumstances. The count starts from zero for each position in the subject
2341    string (for non-anchored patterns). The default limit is, for compatibility, a
2342    large number, namely 10 000 000. You can change this in two ways:
2344    (a) When configuring PCRE before making, you can use --with-match-limit=n
2345        to set a default value for the compiled library.
2347    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2348        a different value is set. See 45 below.
2350    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2352    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2353    of things that can be changed at compile time. The first argument specifies
2354    what is wanted and the second points to where the information is to be placed.
2355    The current list of available information is:
2357      PCRE_CONFIG_UTF8
2359    The output is an integer that is set to one if UTF-8 support is available;
2360    otherwise it is set to zero.
2364    The output is an integer that it set to the value of the code that is used for
2365    newline. It is either LF (10) or CR (13).
2369    The output is an integer that contains the number of bytes used for internal
2370    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2374    The output is an integer that contains the threshold above which the POSIX
2375    interface uses malloc() for output vectors. See item 31 above.
2379    The output is an unsigned integer that contains the default limit of the number
2380    of match() calls in a pcre_exec() execution. See 42 above.
2382    44. pcretest has been upgraded by the addition of the -C option. This causes it
2383    to extract all the available output from the new pcre_config() function, and to
2384    output it. The program then exits immediately.
2386    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2387    order to support additional features. One way would have been to define
2388    pcre_exec2() (for example) with extra arguments, but this would not have been
2389    extensible, and would also have required all calls to the original function to
2390    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2391    is used for passing in "extra" data from pcre_study().
2393    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2394    contains the following fields:
2396      flags         a bitmap indicating which of the following fields are set
2397      study_data    opaque data from pcre_study()
2398      match_limit   a way of specifying a limit on match() calls for a specific
2399                      call to pcre_exec()
2400      callout_data  data for callouts (see 49 below)
2402    The flag bits are also defined in pcre.h, and are
2408    The pcre_study() function now returns one of these new pcre_extra blocks, with
2409    the actual study data pointed to by the study_data field, and the
2410    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2411    before. That is, this change is entirely upwards-compatible and requires no
2412    change to existing code.
2414    If you want to pass in additional data to pcre_exec(), you can either place it
2415    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2416    block.
2418    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2419    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2420    times with different match limits, until it finds the minimum value needed for
2421    pcre_exec() to complete. The value is then output. This can be instructive; for
2422    most simple matches the number is quite small, but for pathological cases it
2423    gets very large very quickly.
2425    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2426    returns the size of the data block pointed to by the study_data field in a
2427    pcre_extra block, that is, the value that was passed as the argument to
2428    pcre_malloc() when PCRE was getting memory in which to place the information
2429    created by pcre_study(). The fourth argument should point to a size_t variable.
2430    pcretest has been extended so that this information is shown after a successful
2431    pcre_study() call when information about the compiled regex is being displayed.
2433    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2434    because what follows is always an absolute path. (Later: it turns out that this
2435    is more than cosmetic for MinGW, because it doesn't like empty path
2436    components.)
2438    49. Some changes have been made to the callout feature (see 28 above):
2440    (i)  A callout function now has three choices for what it returns:
2442           0  =>  success, carry on matching
2443         > 0  =>  failure at this point, but backtrack if possible
2444         < 0  =>  serious error, return this value from pcre_exec()
2446         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2447         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2448         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2449         use by callout functions. It will never be used by PCRE itself.
2451    (ii) The pcre_extra structure (see 45 above) has a void * field called
2452         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2453         pcre_callout_block structure has a field of the same name. The contents of
2454         the field passed in the pcre_extra structure are passed to the callout
2455         function in the corresponding field in the callout block. This makes it
2456         easier to use the same callout-containing regex from multiple threads. For
2457         testing, the pcretest program has a new data escape
2459           \C*n        pass the number n (may be negative) as callout_data
2461         If the callout function in pcretest receives a non-zero value as
2462         callout_data, it returns that value.
2464    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2465    there were some redundant $(CFLAGS) in commands that are now specified as
2466    $(LINK), which already includes $(CFLAGS).
2468    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2469    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2470    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2471    one-byte characters throughout. Note that case-insensitive matching applies
2472    only to characters whose values are less than 256. PCRE doesn't support the
2473    notion of cases for higher-valued characters.
2475    (i)   A character class whose characters are all within 0-255 is handled as
2476          a bit map, and the map is inverted for negative classes. Previously, a
2477          character > 255 always failed to match such a class; however it should
2478          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2480    (ii)  A negated character class with a single character < 255 is coded as
2481          "not this character" (OP_NOT). This wasn't working properly when the test
2482          character was multibyte, either singly or repeated.
2484    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2485          mode, for example: \x{100}{2,3}.
2487    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2488          singly or repeated) now correctly test multibyte characters. However,
2489          PCRE doesn't recognize any characters with values greater than 255 as
2490          digits, spaces, or word characters. Such characters always match \D, \S,
2491          and \W, and never match \d, \s, or \w.
2493    (v)   Classes may now contain characters and character ranges with values
2494          greater than 255. For example: [ab\x{100}-\x{400}].
2496    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2497          PCRE in UTF-8 mode.
2499    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2500    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2501    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2502    value.)
2504    53. The single man page has become too large. I have therefore split it up into
2505    a number of separate man pages. These also give rise to individual HTML pages;
2506    these are now put in a separate directory, and there is an index.html page that
2507    lists them all. Some hyperlinking between the pages has been installed.
2509    54. Added convenience functions for handling named capturing parentheses.
2511    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2512    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2513    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2514    are faulted.
2516    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2517    calling configure. These values are used when compiling the dftables.c program
2518    which is run to generate the source of the default character tables. They
2519    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2520    you will need to set these values.
2522    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2525    Version 3.9 02-Jan-02
2526    ---------------------
2528    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2530    2. If --disable-static was given, the building process failed when trying to
2531    build pcretest and pcregrep. (For some reason it was using libtool to compile
2532    them, which is not right, as they aren't part of the library.)
2535    Version 3.8 18-Dec-01
2536    ---------------------
2538    1. The experimental UTF-8 code was completely screwed up. It was packing the
2539    bytes in the wrong order. How dumb can you get?
2542    Version 3.7 29-Oct-01
2543    ---------------------
2545    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2546    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2547    this didn't happen under Solaris 8, where I normally test things.
2549    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2550    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2551    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2552    this fix an hour or so after the initial 3.7 release.)
2555    Version 3.6 23-Oct-01
2556    ---------------------
2558    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2559    offsets passed as NULL with zero offset count.
2561    2. The config.guess and config.sub files had not been updated when I moved to
2562    the latest autoconf.
2565    Version 3.5 15-Aug-01
2566    ---------------------
2568    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2569    had been forgotten.
2571    2. By using declared but undefined structures, we can avoid using "void"
2572    definitions in pcre.h while keeping the internal definitions of the structures
2573    private.
2575    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2576    user point of view, this means that both static and shared libraries are built
2577    by default, but this can be individually controlled. More of the work of
2578    handling this static/shared cases is now inside libtool instead of PCRE's make
2579    file.
2581    4. The pcretest utility is now installed along with pcregrep because it is
2582    useful for users (to test regexs) and by doing this, it automatically gets
2583    relinked by libtool. The documentation has been turned into a man page, so
2584    there are now .1, .txt, and .html versions in /doc.
2586    5. Upgrades to pcregrep:
2587       (i)   Added long-form option names like gnu grep.
2588       (ii)  Added --help to list all options with an explanatory phrase.
2589       (iii) Added -r, --recursive to recurse into sub-directories.
2590       (iv)  Added -f, --file to read patterns from a file.
2592    6. pcre_exec() was referring to its "code" argument before testing that
2593    argument for NULL (and giving an error if it was NULL).
2595    7. Upgraded Makefile.in to allow for compiling in a different directory from
2596    the source directory.
2598    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2599    options bits, the pointer it was passed was to an int instead of to an unsigned
2600    long int. This mattered only on 64-bit systems.
2602    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2603    generated) instead of pcre.in, which it its source. Also made the same change
2604    in several of the .c files.
2606    10. A new release of gcc defines printf() as a macro, which broke pcretest
2607    because it had an ifdef in the middle of a string argument for printf(). Fixed
2608    by using separate calls to printf().
2610    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2611    script, to force use of CR or LF instead of \n in the source. On non-Unix
2612    systems, the value can be set in config.h.
2614    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2615    absolute limit. Changed the text of the error message to make this clear, and
2616    likewise updated the man page.
2618    13. The limit of 99 on the number of capturing subpatterns has been removed.
2619    The new limit is 65535, which I hope will not be a "real" limit.
2622    Version 3.4 22-Aug-00
2623    ---------------------
2625    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2627    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2630    Version 3.3 01-Aug-00
2631    ---------------------
2633    1. If an octal character was given, but the value was greater than \377, it
2634    was not getting masked to the least significant bits, as documented. This could
2635    lead to crashes in some systems.
2637    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2638    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2640    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2641    These just pass their arguments on to (pcre_free)(), but they are provided
2642    because some uses of PCRE bind it to non-C systems that can call its functions,
2643    but cannot call free() or pcre_free() directly.
2645    4. Add "make test" as a synonym for "make check". Corrected some comments in
2646    the Makefile.
2648    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2649    Makefile.
2651    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2652    command called pgrep for grepping around the active processes.
2654    7. Added the beginnings of support for UTF-8 character strings.
2656    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2657    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2658    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2659    out for the ar command.)
2662    Version 3.2 12-May-00
2663    ---------------------
2665    This is purely a bug fixing release.
2667    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2668    of ZA. This was just one example of several cases that could provoke this bug,
2669    which was introduced by change 9 of version 2.00. The code for breaking
2670    infinite loops after an iteration that matches an empty string was't working
2671    correctly.
2673    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2674    when matched against abbab (for example). After matching an empty string, it
2675    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2676    caused it to match further down the string than it should.
2678    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2679    was there because it doesn't seem to be needed, and it causes trouble on some
2680    systems, as it is not a Standard C header. It has been removed.
2682    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2683    were reported on the Macintosh. The changes were from
2685      while ((c = *(++ptr)) != 0 && c != '\n');
2686    to
2687      while ((c = *(++ptr)) != 0 && c != '\n') ;
2689    Totally extraordinary, but if that's what it takes...
2691    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2692    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2693    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2694    assumes the way PCRE uses memmove() (always moving upwards).
2696    6. PCRE is being used in one environment where strchr() is not available. There
2697    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2698    faster code anyway.
2701    Version 3.1 09-Feb-00
2702    ---------------------
2704    The only change in this release is the fixing of some bugs in Makefile.in for
2705    the "install" target:
2707    (1) It was failing to install pcreposix.h.
2709    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2712    Version 3.0 01-Feb-00
2713    ---------------------
2715    1. Add support for the /+ modifier to perltest (to output $` like it does in
2716    pcretest).
2718    2. Add support for the /g modifier to perltest.
2720    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2721    matches null strings.
2723    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2724    pattern. Perl treats empty patterns specially - it reuses the most recent
2725    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2726    effect.
2728    5. The POSIX interface was broken in that it was just handing over the POSIX
2729    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2730    required a bigger vector, with some working space on the end. This means that
2731    the POSIX wrapper now has to get and free some memory, and copy the results.
2733    6. Added some simple autoconf support, placing the test data and the
2734    documentation in separate directories, re-organizing some of the
2735    information files, and making it build pcre-config (a GNU standard). Also added
2736    libtool support for building PCRE as a shared library, which is now the
2737    default.
2739    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2740    09 are not valid octal constants. Single digits will be used for minor values
2741    less than 10.
2743    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2744    existing programs that set these in the POSIX interface can use PCRE without
2745    modification.
2747    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2748    return all that pcre_info() returns, plus additional data. The pcre_info()
2749    function is retained for compatibility, but is considered to be obsolete.
2751    10. Added experimental recursion feature (?R) to handle one common case that
2752    Perl 5.6 will be able to do with (?p{...}).
2754    11. Added support for POSIX character classes like [:alpha:], which Perl is
2755    adopting.
2758    Version 2.08 31-Aug-99
2759    ----------------------
2761    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2762    trying to match at the startoffset position, but instead was moving forward to
2763    the next newline as if a previous match had failed.
2765    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2766    and could get into a loop if a null string was matched other than at the start
2767    of the subject.
2769    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2770    be distinguished at compile time, and for completeness also added PCRE_DATE.
2772    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2773    in GnuWin32 environments.
2776    Version 2.07 29-Jul-99
2777    ----------------------
2779    1. The documentation is now supplied in plain text form and HTML as well as in
2780    the form of man page sources.
2782    2. C++ compilers don't like assigning (void *) values to other pointer types.
2783    In particular this affects malloc(). Although there is no problem in Standard
2784    C, I've put in casts to keep C++ compilers happy.
2786    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2787    should be (const char *).
2789    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2790    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2791    However, I haven't made this a standard facility. The documentation doesn't
2792    mention it, and the Makefile doesn't support it.
2794    5. The Makefile now contains an "install" target, with editable destinations at
2795    the top of the file. The pcretest program is not installed.
2797    6. pgrep -V now gives the PCRE version number and date.
2799    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2800    causing the entire string to be ignored, instead of just the last character.
2802    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2803    non-matching string, it can take a very, very long time, even for strings of
2804    quite modest length, because of the nested recursion. PCRE now does better in
2805    some of these cases. It does this by remembering the last required literal
2806    character in the pattern, and pre-searching the subject to ensure it is present
2807    before running the real match. In other words, it applies a heuristic to detect
2808    some types of certain failure quickly, and in the above example, if presented
2809    with a string that has no trailing " it gives "no match" very quickly.
2811    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2812    other alternatives are tried instead.
2815    Version 2.06 09-Jun-99
2816    ----------------------
2818    1. Change pcretest's output for amount of store used to show just the code
2819    space, because the remainder (the data block) varies in size between 32-bit and
2820    64-bit systems.
2822    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2823    start matching at. This allows lookbehinds to work when searching for multiple
2824    occurrences in a string.
2826    3. Added additional options to pcretest for testing multiple occurrences:
2828       /+   outputs the rest of the string that follows a match
2829       /g   loops for multiple occurrences, using the new startoffset argument
2830       /G   loops for multiple occurrences by passing an incremented pointer
2832    4. PCRE wasn't doing the "first character" optimization for patterns starting
2833    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2834    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2835    the letter 'x'. On long subject strings, this gives a significant speed-up.
2838    Version 2.05 21-Apr-99
2839    ----------------------
2841    1. Changed the type of magic_number from int to long int so that it works
2842    properly on 16-bit systems.
2844    2. Fixed a bug which caused patterns starting with .* not to work correctly
2845    when the subject string contained newline characters. PCRE was assuming
2846    anchoring for such patterns in all cases, which is not correct because .* will
2847    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2848    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2849    must be retried after every newline in the subject.
2852    Version 2.04 18-Feb-99
2853    ----------------------
2855    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2856    computation of the store needed to hold the pattern was incorrect (too large).
2857    If such patterns were nested a few deep, this could multiply and become a real
2858    problem.
2860    2. Added /M option to pcretest to show the memory requirement of a specific
2861    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2863    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2864    compiled in such a way that the backtracking after subsequent failure was
2865    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2866    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2869    Version 2.03 02-Feb-99
2870    ----------------------
2872    1. Fixed typo and small mistake in man page.
2874    2. Added 4th condition (GPL supersedes if conflict) and created separate
2875    LICENCE file containing the conditions.
2877    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2878    Perl, that is the internal \ allows the delimiter to be included in the
2879    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2880    the final delimiter, add \ to the end of the pattern (to test the error).
2882    4. Added the convenience functions for extracting substrings after a successful
2883    match. Updated pcretest to make it able to test these functions.
2886    Version 2.02 14-Jan-99
2887    ----------------------
2889    1. Initialized the working variables associated with each extraction so that
2890    their saving and restoring doesn't refer to uninitialized store.
2892    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2893    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2894    fix the problem.
2896    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2897    calls, and wasn't printing the correct value for compiling calls. Increased the
2898    default value of LOOPREPEAT, and the number of significant figures in the
2899    times.
2901    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2903    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2904    a building problem on Windows NT with a FAT file system.
2907    Version 2.01 21-Oct-98
2908    ----------------------
2910    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2911    to character tables built by pcre_maketables() in the current locale. If NULL
2912    is passed, the default tables are used.
2915    Version 2.00 24-Sep-98
2916    ----------------------
2918    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2919    it any more.
2921    2. Allow quantification of (?>) groups, and make it work correctly.
2923    3. The first character computation wasn't working for (?>) groups.
2925    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2926    end of the subject) and add 5.005's \z, which really does match only at the
2927    very end of the subject.
2929    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2931    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2932    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2933    localized options. All options to pcre_study() were also removed.
2935    7. Add other new features from 5.005:
2937       $(?<=           positive lookbehind
2938       $(?<!           negative lookbehind
2939       (?imsx-imsx)    added the unsetting capability
2940                       such a setting is global if at outer level; local otherwise
2941       (?imsx-imsx:)   non-capturing groups with option setting
2942       (?(cond)re|re)  conditional pattern matching
2944       A backreference to itself in a repeated group matches the previous
2945       captured string.
2947    8. General tidying up of studying (both automatic and via "study")
2948    consequential on the addition of new assertions.
2950    9. As in 5.005, unlimited repeated groups that could match an empty substring
2951    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2952    runtime if any iteration does actually match an empty substring.
2954    10. Include the RunTest script in the distribution.
2956    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2957    discrepancies, some of which were old and were also with respect to 5.004. They
2958    have now been fixed.
2961    Version 1.09 28-Apr-98
2962    ----------------------
2964    1. A negated single character class followed by a quantifier with a minimum
2965    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2966    program crashes, or just wrong answers. This did not apply to negated classes
2967    containing more than one character, or to minima other than one.
2970  Version 1.08 27-Mar-98  Version 1.08 27-Mar-98
2971  ----------------------  ----------------------

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