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revision 19 by nigel, Sat Feb 24 21:38:33 2007 UTC revision 123 by ph10, Mon Mar 12 15:19:06 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 12-Mar-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files !compile.txt,
36        !linklib.txt, and pcregexp.pas.
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
65        (a) It was defining its arguments as char * instead of void *.
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
98    13. Some tidying changes to the testing mechanism:
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
120    Version 7.0 19-Dec-06
121    ---------------------
123     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
124        moving to gcc 4.1.1.
126     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
127        sys/time.h, which is documented as needed for this function. It doesn't
128        seem to matter on Linux, but it showed up on some releases of OS X.
130     3. It seems that there are systems where bytes whose values are greater than
131        127 match isprint() in the "C" locale. The "C" locale should be the
132        default when a C program starts up. In most systems, only ASCII printing
133        characters match isprint(). This difference caused the output from pcretest
134        to vary, making some of the tests fail. I have changed pcretest so that:
136        (a) When it is outputting text in the compiled version of a pattern, bytes
137            other than 32-126 are always shown as hex escapes.
139        (b) When it is outputting text that is a matched part of a subject string,
140            it does the same, unless a different locale has been set for the match
141            (using the /L modifier). In this case, it uses isprint() to decide.
143     4. Fixed a major bug that caused incorrect computation of the amount of memory
144        required for a compiled pattern when options that changed within the
145        pattern affected the logic of the preliminary scan that determines the
146        length. The relevant options are -x, and -i in UTF-8 mode. The result was
147        that the computed length was too small. The symptoms of this bug were
148        either the PCRE error "internal error: code overflow" from pcre_compile(),
149        or a glibc crash with a message such as "pcretest: free(): invalid next
150        size (fast)". Examples of patterns that provoked this bug (shown in
151        pcretest format) are:
153          /(?-x: )/x
154          /(?x)(?-x: \s*#\s*)/
155          /((?i)[\x{c0}])/8
156          /(?i:[\x{c0}])/8
158        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
159        is now done differently.
161     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
162        wrapper classes; (b) implement a new function in the C++ scanner that is
163        more efficient than the old way of doing things because it avoids levels of
164        recursion in the regex matching; (c) add a paragraph to the documentation
165        for the FullMatch() function.
167     6. The escape sequence \n was being treated as whatever was defined as
168        "newline". Not only was this contrary to the documentation, which states
169        that \n is character 10 (hex 0A), but it also went horribly wrong when
170        "newline" was defined as CRLF. This has been fixed.
172     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
173        was being set to -1 for the "end of line" case (supposedly a value that no
174        character can have). Though this value is never used (the check for end of
175        line is "zero bytes in current character"), it caused compiler complaints.
176        I've changed it to 0xffffffff.
178     8. In pcre_version.c, the version string was being built by a sequence of
179        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
180        string (as it is for production releases) called a macro with an empty
181        argument. The C standard says the result of this is undefined. The gcc
182        compiler treats it as an empty string (which was what was wanted) but it is
183        reported that Visual C gives an error. The source has been hacked around to
184        avoid this problem.
186     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
187        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
188        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
189        of them did).
191    10. Originally, pcretest opened its input and output without "b"; then I was
192        told that "b" was needed in some environments, so it was added for release
193        5.0 to both the input and output. (It makes no difference on Unix-like
194        systems.) Later I was told that it is wrong for the input on Windows. I've
195        now abstracted the modes into two macros, to make it easier to fiddle with
196        them, and removed "b" from the input mode under Windows.
198    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
200    12. Added -help and --help to pcretest as an official way of being reminded
201        of the options.
203    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
204        and pcrecpp.cc because they annoy compilers at high warning levels.
206    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
208    15. Fixed an occurrence of == in configure.ac that should have been = (shell
209        scripts are not C programs :-) and which was not noticed because it works
210        on Linux.
212    16. pcretest is supposed to handle any length of pattern and data line (as one
213        line or as a continued sequence of lines) by extending its input buffer if
214        necessary. This feature was broken for very long pattern lines, leading to
215        a string of junk being passed to pcre_compile() if the pattern was longer
216        than about 50K.
218    17. I have done a major re-factoring of the way pcre_compile() computes the
219        amount of memory needed for a compiled pattern. Previously, there was code
220        that made a preliminary scan of the pattern in order to do this. That was
221        OK when PCRE was new, but as the facilities have expanded, it has become
222        harder and harder to keep it in step with the real compile phase, and there
223        have been a number of bugs (see for example, 4 above). I have now found a
224        cunning way of running the real compile function in a "fake" mode that
225        enables it to compute how much memory it would need, while actually only
226        ever using a few hundred bytes of working memory and without too many
227        tests of the mode. This should make future maintenance and development
228        easier. A side effect of this work is that the limit of 200 on the nesting
229        depth of parentheses has been removed (though this was never a serious
230        limitation, I suspect). However, there is a downside: pcre_compile() now
231        runs more slowly than before (30% or more, depending on the pattern). I
232        hope this isn't a big issue. There is no effect on runtime performance.
234    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
235        newline (only possible for the last line of a file) and it was a
236        pattern that set a locale (followed by /Lsomething), pcretest crashed.
238    19. Added additional timing features to pcretest. (1) The -tm option now times
239        matching only, not compiling. (2) Both -t and -tm can be followed, as a
240        separate command line item, by a number that specifies the number of
241        repeats to use when timing. The default is 50000; this gives better
242        precision, but takes uncomfortably long for very large patterns.
244    20. Extended pcre_study() to be more clever in cases where a branch of a
245        subpattern has no definite first character. For example, (a*|b*)[cd] would
246        previously give no result from pcre_study(). Now it recognizes that the
247        first character must be a, b, c, or d.
249    21. There was an incorrect error "recursive call could loop indefinitely" if
250        a subpattern (or the entire pattern) that was being tested for matching an
251        empty string contained only one non-empty item after a nested subpattern.
252        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
253        incorrectly, because the \d was being skipped in the check.
255    22. The pcretest program now has a new pattern option /B and a command line
256        option -b, which is equivalent to adding /B to every pattern. This causes
257        it to show the compiled bytecode, without the additional information that
258        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
259        is the same as /B/I).
261    23. A new optimization is now able automatically to treat some sequences such
262        as a*b as a*+b. More specifically, if something simple (such as a character
263        or a simple class like \d) has an unlimited quantifier, and is followed by
264        something that cannot possibly match the quantified thing, the quantifier
265        is automatically "possessified".
267    24. A recursive reference to a subpattern whose number was greater than 39
268        went wrong under certain circumstances in UTF-8 mode. This bug could also
269        have affected the operation of pcre_study().
271    25. Realized that a little bit of performance could be had by replacing
272        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
274    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
276    27. Possessive quantifiers such as a++ were previously implemented by turning
277        them into atomic groups such as ($>a+). Now they have their own opcodes,
278        which improves performance. This includes the automatically created ones
279        from 23 above.
281    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
282        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
283        the first matched character to be a colon. This applied both to named and
284        numbered groups.
286    29. The ucpinternal.h header file was missing its idempotency #ifdef.
288    30. I was sent a "project" file called libpcre.a.dev which I understand makes
289        building PCRE on Windows easier, so I have included it in the distribution.
291    31. There is now a check in pcretest against a ridiculously large number being
292        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
293        loop, the loop is abandoned.
295    32. Forward references to subpatterns in conditions such as (?(2)...) where
296        subpattern 2 is defined later cause pcre_compile() to search forwards in
297        the pattern for the relevant set of parentheses. This search went wrong
298        when there were unescaped parentheses in a character class, parentheses
299        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
301    33. "Subroutine" calls and backreferences were previously restricted to
302        referencing subpatterns earlier in the regex. This restriction has now
303        been removed.
305    34. Added a number of extra features that are going to be in Perl 5.10. On the
306        whole, these are just syntactic alternatives for features that PCRE had
307        previously implemented using the Python syntax or my own invention. The
308        other formats are all retained for compatibility.
310        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
311            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
312            also .NET compatible.
314        (b) A recursion or subroutine call to a named group can now be defined as
315            (?&name) as well as (?P>name).
317        (c) A backreference to a named group can now be defined as \k<name> or
318            \k'name' as well as (?P=name). The new forms, as well as being in Perl
319            5.10, are also .NET compatible.
321        (d) A conditional reference to a named group can now use the syntax
322            (?(<name>) or (?('name') as well as (?(name).
324        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
325            groups (named and numbered) that are never evaluated inline, but can be
326            called as "subroutines" from elsewhere. In effect, the DEFINE condition
327            is always false. There may be only one alternative in such a group.
329        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
330            as the simple (?(R). The condition is true only if the most recent
331            recursion is that of the given number or name. It does not search out
332            through the entire recursion stack.
334        (g) The escape \gN or \g{N} has been added, where N is a positive or
335            negative number, specifying an absolute or relative reference.
337    35. Tidied to get rid of some further signed/unsigned compiler warnings and
338        some "unreachable code" warnings.
340    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
341        things, this adds five new scripts.
343    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
344        There were also incompatibilities regarding the handling of \Q..\E inside
345        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
346        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
348    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
349        matches an empty string, and forcibly breaks the loop. There were bugs in
350        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
351        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
352        separate and independent bugs (that affected different cases) have been
353        fixed.
355    39. Refactored the code to abolish the use of different opcodes for small
356        capturing bracket numbers. This is a tidy that I avoided doing when I
357        removed the limit on the number of capturing brackets for 3.5 back in 2001.
358        The new approach is not only tidier, it makes it possible to reduce the
359        memory needed to fix the previous bug (38).
361    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
362        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
363        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
364        mode.
366    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
367        report.
369    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
370        copy construction and assignment in the C++ wrapper.
372    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
373        couple of bugs that could have given wrong results in the "--newline=crlf"
374        case.
376    44. Added a number of casts and did some reorganization of signed/unsigned int
377        variables following suggestions from Dair Grant. Also renamed the variable
378        "this" as "item" because it is a C++ keyword.
380    45. Arranged for dftables to add
382          #include "pcre_internal.h"
384        to pcre_chartables.c because without it, gcc 4.x may remove the array
385        definition from the final binary if PCRE is built into a static library and
386        dead code stripping is activated.
388    46. For an unanchored pattern, if a match attempt fails at the start of a
389        newline sequence, and the newline setting is CRLF or ANY, and the next two
390        characters are CRLF, advance by two characters instead of one.
393    Version 6.7 04-Jul-06
394    ---------------------
396     1. In order to handle tests when input lines are enormously long, pcretest has
397        been re-factored so that it automatically extends its buffers when
398        necessary. The code is crude, but this _is_ just a test program. The
399        default size has been increased from 32K to 50K.
401     2. The code in pcre_study() was using the value of the re argument before
402        testing it for NULL. (Of course, in any sensible call of the function, it
403        won't be NULL.)
405     3. The memmove() emulation function in pcre_internal.h, which is used on
406        systems that lack both memmove() and bcopy() - that is, hardly ever -
407        was missing a "static" storage class specifier.
409     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
410        containing an extended class (one that cannot be represented by a bitmap
411        because it contains high-valued characters or Unicode property items, e.g.
412        [\pZ]). Almost always one would set UTF-8 mode when processing such a
413        pattern, but PCRE should not loop if you do not (it no longer does).
414        [Detail: two cases were found: (a) a repeated subpattern containing an
415        extended class; (b) a recursive reference to a subpattern that followed a
416        previous extended class. It wasn't skipping over the extended class
417        correctly when UTF-8 mode was not set.]
419     5. A negated single-character class was not being recognized as fixed-length
420        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
421        compile error "lookbehind assertion is not fixed length".
423     6. The RunPerlTest auxiliary script was showing an unexpected difference
424        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
425        write a Perl script that can interpret lines of an input file either as
426        byte characters or as UTF-8, which is what "perltest" was being required to
427        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
428        can't do is switch easily at run time between having the "use utf8;" pragma
429        or not. In the end, I fudged it by using the RunPerlTest script to insert
430        "use utf8;" explicitly for the UTF-8 tests.
432     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
433        the end of the subject string, contrary to the documentation and to what
434        Perl does. This was true of both matching functions. Now it matches only at
435        the start of the subject and immediately after *internal* newlines.
437     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
438        a pointer to an int instead of a pointer to an unsigned long int. This
439        caused problems on 64-bit systems.
441     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
442        instance of the 'standard' template library not being so standard".
444    10. There was no check on the number of named subpatterns nor the maximum
445        length of a subpattern name. The product of these values is used to compute
446        the size of the memory block for a compiled pattern. By supplying a very
447        long subpattern name and a large number of named subpatterns, the size
448        computation could be caused to overflow. This is now prevented by limiting
449        the length of names to 32 characters, and the number of named subpatterns
450        to 10,000.
452    11. Subpatterns that are repeated with specific counts have to be replicated in
453        the compiled pattern. The size of memory for this was computed from the
454        length of the subpattern and the repeat count. The latter is limited to
455        65535, but there was no limit on the former, meaning that integer overflow
456        could in principle occur. The compiled length of a repeated subpattern is
457        now limited to 30,000 bytes in order to prevent this.
459    12. Added the optional facility to have named substrings with the same name.
461    13. Added the ability to use a named substring as a condition, using the
462        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
463        are numbers (not recommended). Forward references are permitted.
465    14. Added forward references in named backreferences (if you see what I mean).
467    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
468        pattern could run off the end of the subject. For example, the pattern
469        "(?s)(.{1,5})"8 did this with the subject "ab".
471    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
472        PCRE_CASELESS was set when matching characters that were quantified with ?
473        or *.
475    17. A character class other than a single negated character that had a minimum
476        but no maximum quantifier - for example [ab]{6,} - was not handled
477        correctly by pce_dfa_exec(). It would match only one character.
479    18. A valid (though odd) pattern that looked like a POSIX character
480        class but used an invalid character after [ (for example [[,abc,]]) caused
481        pcre_compile() to give the error "Failed: internal error: code overflow" or
482        in some cases to crash with a glibc free() error. This could even happen if
483        the pattern terminated after [[ but there just happened to be a sequence of
484        letters, a binary zero, and a closing ] in the memory that followed.
486    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
487        over the years. Originally (before any Unicode support), just the bottom 8
488        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
489        output from "man perlunicode" includes this:
491          The regular expression compiler produces polymorphic opcodes.  That
492          is, the pattern adapts to the data and automatically switches to
493          the Unicode character scheme when presented with Unicode data--or
494          instead uses a traditional byte scheme when presented with byte
495          data.
497        Sadly, a wide octal escape does not cause a switch, and in a string with
498        no other multibyte characters, these octal escapes are treated as before.
499        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
500        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
501        Unicode string.
503        I have not perpetrated such confusion in PCRE. Up till now, it took just
504        the bottom 8 bits, as in old Perl. I have now made octal escapes with
505        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
506        translate to the appropriate multibyte character.
508    29. Applied some refactoring to reduce the number of warnings from Microsoft
509        and Borland compilers. This has included removing the fudge introduced
510        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
511        a warning about an unused variable.
513    21. PCRE has not included VT (character 0x0b) in the set of whitespace
514        characters since release 4.0, because Perl (from release 5.004) does not.
515        [Or at least, is documented not to: some releases seem to be in conflict
516        with the documentation.] However, when a pattern was studied with
517        pcre_study() and all its branches started with \s, PCRE still included VT
518        as a possible starting character. Of course, this did no harm; it just
519        caused an unnecessary match attempt.
521    22. Removed a now-redundant internal flag bit that recorded the fact that case
522        dependency changed within the pattern. This was once needed for "required
523        byte" processing, but is no longer used. This recovers a now-scarce options
524        bit. Also moved the least significant internal flag bit to the most-
525        significant bit of the word, which was not previously used (hangover from
526        the days when it was an int rather than a uint) to free up another bit for
527        the future.
529    23. Added support for CRLF line endings as well as CR and LF. As well as the
530        default being selectable at build time, it can now be changed at runtime
531        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
532        specify that it is scanning data with non-default line endings.
534    24. Changed the definition of CXXLINK to make it agree with the definition of
535        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
537    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
538        recursions. This makes a big different to stack usage for some patterns.
540    26. If a subpattern containing a named recursion or subroutine reference such
541        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
542        the space required for the compiled pattern went wrong and gave too small a
543        value. Depending on the environment, this could lead to "Failed: internal
544        error: code overflow at offset 49" or "glibc detected double free or
545        corruption" errors.
547    27. Applied patches from Google (a) to support the new newline modes and (b) to
548        advance over multibyte UTF-8 characters in GlobalReplace.
550    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
551        difference for some implementation of PCRE in some Windows version.
553    29. Added some extra testing facilities to pcretest:
555        \q<number>   in a data line sets the "match limit" value
556        \Q<number>   in a data line sets the "match recursion limt" value
557        -S <number>  sets the stack size, where <number> is in megabytes
559        The -S option isn't available for Windows.
562    Version 6.6 06-Feb-06
563    ---------------------
565     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
566        in pcreposix.h. I have copied the definition from pcre.h.
568     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
569        because pcre.h is no longer a built file.
571     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
572        not normally included in the compiled code.
575    Version 6.5 01-Feb-06
576    ---------------------
578     1. When using the partial match feature with pcre_dfa_exec(), it was not
579        anchoring the second and subsequent partial matches at the new starting
580        point. This could lead to incorrect results. For example, with the pattern
581        /1234/, partially matching against "123" and then "a4" gave a match.
583     2. Changes to pcregrep:
585        (a) All non-match returns from pcre_exec() were being treated as failures
586            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
587            error message is output. Some extra information is given for the
588            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
589            probably the only errors that are likely to be caused by users (by
590            specifying a regex that has nested indefinite repeats, for instance).
591            If there are more than 20 of these errors, pcregrep is abandoned.
593        (b) A binary zero was treated as data while matching, but terminated the
594            output line if it was written out. This has been fixed: binary zeroes
595            are now no different to any other data bytes.
597        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
598            used to set a locale for matching. The --locale=xxxx long option has
599            been added (no short equivalent) to specify a locale explicitly on the
600            pcregrep command, overriding the environment variables.
602        (d) When -B was used with -n, some line numbers in the output were one less
603            than they should have been.
605        (e) Added the -o (--only-matching) option.
607        (f) If -A or -C was used with -c (count only), some lines of context were
608            accidentally printed for the final match.
610        (g) Added the -H (--with-filename) option.
612        (h) The combination of options -rh failed to suppress file names for files
613            that were found from directory arguments.
615        (i) Added the -D (--devices) and -d (--directories) options.
617        (j) Added the -F (--fixed-strings) option.
619        (k) Allow "-" to be used as a file name for -f as well as for a data file.
621        (l) Added the --colo(u)r option.
623        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
624            is not present by default.
626     3. A nasty bug was discovered in the handling of recursive patterns, that is,
627        items such as (?R) or (?1), when the recursion could match a number of
628        alternatives. If it matched one of the alternatives, but subsequently,
629        outside the recursion, there was a failure, the code tried to back up into
630        the recursion. However, because of the way PCRE is implemented, this is not
631        possible, and the result was an incorrect result from the match.
633        In order to prevent this happening, the specification of recursion has
634        been changed so that all such subpatterns are automatically treated as
635        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
637     4. I had overlooked the fact that, in some locales, there are characters for
638        which isalpha() is true but neither isupper() nor islower() are true. In
639        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
640        and ordfeminine) are like this. This affected the treatment of \w and \W
641        when they appeared in character classes, but not when they appeared outside
642        a character class. The bit map for "word" characters is now created
643        separately from the results of isalnum() instead of just taking it from the
644        upper, lower, and digit maps. (Plus the underscore character, of course.)
646     5. The above bug also affected the handling of POSIX character classes such as
647        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
648        permanent tables. Instead, the bit maps for such a class were previously
649        created as the appropriate unions of the upper, lower, and digit bitmaps.
650        Now they are created by subtraction from the [[:word:]] class, which has
651        its own bitmap.
653     6. The [[:blank:]] character class matches horizontal, but not vertical space.
654        It is created by subtracting the vertical space characters (\x09, \x0a,
655        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
656        subtraction was done in the overall bitmap for a character class, meaning
657        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
658        be recognized. This bug has been fixed.
660     7. Patches from the folks at Google:
662          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
663          real life, but is still worth protecting against".
665          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
666          regular expressions".
668          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
669          have it.
671          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
672          "configure" and the latter not, in order to fix a problem somebody had
673          with compiling the Arg class on HP-UX.
675          (e) Improve the error-handling of the C++ wrapper a little bit.
677          (f) New tests for checking recursion limiting.
679     8. The pcre_memmove() function, which is used only if the environment does not
680        have a standard memmove() function (and is therefore rarely compiled),
681        contained two bugs: (a) use of int instead of size_t, and (b) it was not
682        returning a result (though PCRE never actually uses the result).
684     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
685        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
686        returned instead of calling malloc() with an overflowing number that would
687        most likely cause subsequent chaos.
689    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
691    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
692        with this option is matched, the nmatch and pmatch options of regexec() are
693        ignored.
695    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
696        provided in case anyone wants to the the POSIX interface with UTF-8
697        strings.
699    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
700        C++ linking (needed for some HP-UX environments).
702    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
703        (unused parameter) and in the pcre_printint() function (omitted "default"
704        switch label when the default is to do nothing).
706    15. Added some code to make it possible, when PCRE is compiled as a C++
707        library, to replace subject pointers for pcre_exec() with a smart pointer
708        class, thus making it possible to process discontinuous strings.
710    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
711        much the same function. They were added by different people who were trying
712        to make PCRE easy to compile on non-Unix systems. It has been suggested
713        that PCRE_EXPORT be abolished now that there is more automatic apparatus
714        for compiling on Windows systems. I have therefore replaced it with
715        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
716        defaults to "extern" for C or "extern C" for C++, which works fine on
717        Unix-like systems. It is now possible to override the value of PCRE_DATA_
718        SCOPE with something explicit in config.h. In addition:
720        (a) pcreposix.h still had just "extern" instead of either of these macros;
721            I have replaced it with PCRE_DATA_SCOPE.
723        (b) Functions such as _pcre_xclass(), which are internal to the library,
724            but external in the C sense, all had PCRE_EXPORT in their definitions.
725            This is apparently wrong for the Windows case, so I have removed it.
726            (It makes no difference on Unix-like systems.)
728    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
729        of recursive calls to match(). This is different to MATCH_LIMIT because
730        that limits the total number of calls to match(), not all of which increase
731        the depth of recursion. Limiting the recursion depth limits the amount of
732        stack (or heap if NO_RECURSE is set) that is used. The default can be set
733        when PCRE is compiled, and changed at run time. A patch from Google adds
734        this functionality to the C++ interface.
736    18. Changes to the handling of Unicode character properties:
738        (a) Updated the table to Unicode 4.1.0.
740        (b) Recognize characters that are not in the table as "Cn" (undefined).
742        (c) I revised the way the table is implemented to a much improved format
743            which includes recognition of ranges. It now supports the ranges that
744            are defined in UnicodeData.txt, and it also amalgamates other
745            characters into ranges. This has reduced the number of entries in the
746            table from around 16,000 to around 3,000, thus reducing its size
747            considerably. I realized I did not need to use a tree structure after
748            all - a binary chop search is just as efficient. Having reduced the
749            number of entries, I extended their size from 6 bytes to 8 bytes to
750            allow for more data.
752        (d) Added support for Unicode script names via properties such as \p{Han}.
754    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
755        matching that character.
757    20. When matching a repeated Unicode property with a minimum greater than zero,
758        (for example \pL{2,}), PCRE could look past the end of the subject if it
759        reached it while seeking the minimum number of characters. This could
760        happen only if some of the characters were more than one byte long, because
761        there is a check for at least the minimum number of bytes.
763    21. Refactored the implementation of \p and \P so as to be more general, to
764        allow for more different types of property in future. This has changed the
765        compiled form incompatibly. Anybody with saved compiled patterns that use
766        \p or \P will have to recompile them.
768    22. Added "Any" and "L&" to the supported property types.
770    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
771        but give a compile time error if the value is greater than 0xff.
773    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
774        accidentally not being installed or uninstalled.
776    25. The pcre.h file was built from pcre.h.in, but the only changes that were
777        made were to insert the current release number. This seemed silly, because
778        it made things harder for people building PCRE on systems that don't run
779        "configure". I have turned pcre.h into a distributed file, no longer built
780        by "configure", with the version identification directly included. There is
781        no longer a pcre.h.in file.
783        However, this change necessitated a change to the pcre-config script as
784        well. It is built from pcre-config.in, and one of the substitutions was the
785        release number. I have updated configure.ac so that ./configure now finds
786        the release number by grepping pcre.h.
788    26. Added the ability to run the tests under valgrind.
791    Version 6.4 05-Sep-05
792    ---------------------
794     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
795        "--" to be printed when multiple files were scanned, even when none of the
796        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
797        consider it to be a bug, and have restored the previous behaviour.
799     2. A couple of code tidies to get rid of compiler warnings.
801     3. The pcretest program used to cheat by referring to symbols in the library
802        whose names begin with _pcre_. These are internal symbols that are not
803        really supposed to be visible externally, and in some environments it is
804        possible to suppress them. The cheating is now confined to including
805        certain files from the library's source, which is a bit cleaner.
807     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
808        file's purpose clearer.
810     5. Reorganized pcre_ucp_findchar().
813    Version 6.3 15-Aug-05
814    ---------------------
816     1. The file libpcre.pc.in did not have general read permission in the tarball.
818     2. There were some problems when building without C++ support:
820        (a) If C++ support was not built, "make install" and "make test" still
821            tried to test it.
823        (b) There were problems when the value of CXX was explicitly set. Some
824            changes have been made to try to fix these, and ...
826        (c) --disable-cpp can now be used to explicitly disable C++ support.
828        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
829            backslash in a target when C++ was disabled. This confuses some
830            versions of "make", apparently. Using an intermediate variable solves
831            this. (Same for CPP_LOBJ.)
833     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
834        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
835        necessary on certain architectures.
837     4. Added a setting of -export-symbols-regex to the link command to remove
838        those symbols that are exported in the C sense, but actually are local
839        within the library, and not documented. Their names all begin with
840        "_pcre_". This is not a perfect job, because (a) we have to except some
841        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
842        available (and never for static libraries). I have made a note to try to
843        find a way round (a) in the future.
846    Version 6.2 01-Aug-05
847    ---------------------
849     1. There was no test for integer overflow of quantifier values. A construction
850        such as {1111111111111111} would give undefined results. What is worse, if
851        a minimum quantifier for a parenthesized subpattern overflowed and became
852        negative, the calculation of the memory size went wrong. This could have
853        led to memory overwriting.
855     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
857     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
858        operating environments where this matters.
860     4. Applied Giuseppe Maxia's patch to add additional features for controlling
861        PCRE options from within the C++ wrapper.
863     5. Named capturing subpatterns were not being correctly counted when a pattern
864        was compiled. This caused two problems: (a) If there were more than 100
865        such subpatterns, the calculation of the memory needed for the whole
866        compiled pattern went wrong, leading to an overflow error. (b) Numerical
867        back references of the form \12, where the number was greater than 9, were
868        not recognized as back references, even though there were sufficient
869        previous subpatterns.
871     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
872        versions of gcc, e.g. 2.95.4.
875    Version 6.1 21-Jun-05
876    ---------------------
878     1. There was one reference to the variable "posix" in pcretest.c that was not
879        surrounded by "#if !defined NOPOSIX".
881     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
882        the cross-check on the old pcre_info() function, for the benefit of the
883        cut-down version of PCRE that is currently imported into Exim.
885     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
886        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
887        patterns that start (?i) but I don't think that matters. The use of (?i) is
888        just an example; this all applies to the other options as well.
890     4. Since libtool seems to echo the compile commands it is issuing, the output
891        from "make" can be reduced a bit by putting "@" in front of each libtool
892        compile command.
894     5. Patch from the folks at Google for configure.in to be a bit more thorough
895        in checking for a suitable C++ installation before trying to compile the
896        C++ stuff. This should fix a reported problem when a compiler was present,
897        but no suitable headers.
899     6. The man pages all had just "PCRE" as their title. I have changed them to
900        be the relevant file name. I have also arranged that these names are
901        retained in the file doc/pcre.txt, which is a concatenation in text format
902        of all the man pages except the little individual ones for each function.
904     7. The NON-UNIX-USE file had not been updated for the different set of source
905        files that come with release 6. I also added a few comments about the C++
906        wrapper.
909    Version 6.0 07-Jun-05
910    ---------------------
912     1. Some minor internal re-organization to help with my DFA experiments.
914     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
915        didn't matter for the library itself when fully configured, but did matter
916        when compiling without UCP support, or within Exim, where the ucp files are
917        not imported.
919     3. Refactoring of the library code to split up the various functions into
920        different source modules. The addition of the new DFA matching code (see
921        below) to a single monolithic source would have made it really too
922        unwieldy, quite apart from causing all the code to be include in a
923        statically linked application, when only some functions are used. This is
924        relevant even without the DFA addition now that patterns can be compiled in
925        one application and matched in another.
927        The downside of splitting up is that there have to be some external
928        functions and data tables that are used internally in different modules of
929        the library but which are not part of the API. These have all had their
930        names changed to start with "_pcre_" so that they are unlikely to clash
931        with other external names.
933     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
934        a different (DFA) algorithm. Although it is slower than the original
935        function, it does have some advantages for certain types of matching
936        problem.
938     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
939        including restarting after a partial match.
941     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
942        defined when compiling for Windows was sent to me. I have put it into the
943        code, though I have no means of testing or verifying it.
945     7. Added the pcre_refcount() auxiliary function.
947     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
948        match before or at the first newline in the subject string. In pcretest,
949        the /f option on a pattern can be used to set this.
951     9. A repeated \w when used in UTF-8 mode with characters greater than 256
952        would behave wrongly. This has been present in PCRE since release 4.0.
954    10. A number of changes to the pcregrep command:
956        (a) Refactored how -x works; insert ^(...)$ instead of setting
957            PCRE_ANCHORED and checking the length, in preparation for adding
958            something similar for -w.
960        (b) Added the -w (match as a word) option.
962        (c) Refactored the way lines are read and buffered so as to have more
963            than one at a time available.
965        (d) Implemented a pcregrep test script.
967        (e) Added the -M (multiline match) option. This allows patterns to match
968            over several lines of the subject. The buffering ensures that at least
969            8K, or the rest of the document (whichever is the shorter) is available
970            for matching (and similarly the previous 8K for lookbehind assertions).
972        (f) Changed the --help output so that it now says
974              -w, --word-regex(p)
976            instead of two lines, one with "regex" and the other with "regexp"
977            because that confused at least one person since the short forms are the
978            same. (This required a bit of code, as the output is generated
979            automatically from a table. It wasn't just a text change.)
981        (g) -- can be used to terminate pcregrep options if the next thing isn't an
982            option but starts with a hyphen. Could be a pattern or a path name
983            starting with a hyphen, for instance.
985        (h) "-" can be given as a file name to represent stdin.
987        (i) When file names are being printed, "(standard input)" is used for
988            the standard input, for compatibility with GNU grep. Previously
989            "<stdin>" was used.
991        (j) The option --label=xxx can be used to supply a name to be used for
992            stdin when file names are being printed. There is no short form.
994        (k) Re-factored the options decoding logic because we are going to add
995            two more options that take data. Such options can now be given in four
996            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
998        (l) Added the -A, -B, and -C options for requesting that lines of context
999            around matches be printed.
1001        (m) Added the -L option to print the names of files that do not contain
1002            any matching lines, that is, the complement of -l.
1004        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1005            continue to scan other files.
1007        (o) The -s option was incorrectly implemented. For compatibility with other
1008            greps, it now suppresses the error message for a non-existent or non-
1009            accessible file (but not the return code). There is a new option called
1010            -q that suppresses the output of matching lines, which was what -s was
1011            previously doing.
1013        (p) Added --include and --exclude options to specify files for inclusion
1014            and exclusion when recursing.
1016    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1017        Hopefully, it now does.
1019    12. Missing cast in pcre_study().
1021    13. Added an "uninstall" target to the makefile.
1023    14. Replaced "extern" in the function prototypes in Makefile.in with
1024        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1025        world, but is set differently for Windows.
1027    15. Added a second compiling function called pcre_compile2(). The only
1028        difference is that it has an extra argument, which is a pointer to an
1029        integer error code. When there is a compile-time failure, this is set
1030        non-zero, in addition to the error test pointer being set to point to an
1031        error message. The new argument may be NULL if no error number is required
1032        (but then you may as well call pcre_compile(), which is now just a
1033        wrapper). This facility is provided because some applications need a
1034        numeric error indication, but it has also enabled me to tidy up the way
1035        compile-time errors are handled in the POSIX wrapper.
1037    16. Added VPATH=.libs to the makefile; this should help when building with one
1038        prefix path and installing with another. (Or so I'm told by someone who
1039        knows more about this stuff than I do.)
1041    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1042        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1043        match everything, including newlines. This is not POSIX-compatible, but
1044        somebody wanted the feature. From pcretest it can be activated by using
1045        both the P and the s flags.
1047    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1049    19. libpcre.pc was being incorrectly installed as executable.
1051    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1052        it now also looks for '\r' so that it will work unmodified on Windows.
1054    21. Added Google's contributed C++ wrapper to the distribution.
1056    22. Added some untidy missing memory free() calls in pcretest, to keep
1057        Electric Fence happy when testing.
1061    Version 5.0 13-Sep-04
1062    ---------------------
1064     1. Internal change: literal characters are no longer packed up into items
1065        containing multiple characters in a single byte-string. Each character
1066        is now matched using a separate opcode. However, there may be more than one
1067        byte in the character in UTF-8 mode.
1069     2. The pcre_callout_block structure has two new fields: pattern_position and
1070        next_item_length. These contain the offset in the pattern to the next match
1071        item, and its length, respectively.
1073     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1074        insertion of callouts before each pattern item. Added the /C option to
1075        pcretest to make use of this.
1077     4. On the advice of a Windows user, the lines
1079          #if defined(_WIN32) || defined(WIN32)
1080          _setmode( _fileno( stdout ), 0x8000 );
1081          #endif  /* defined(_WIN32) || defined(WIN32) */
1083        have been added to the source of pcretest. This apparently does useful
1084        magic in relation to line terminators.
1086     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1087        for the benefit of those environments where the "b" makes a difference.
1089     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1090        to know about it. I have put a hack into configure.in that adds in code
1091        to set GCC=yes if CC=icc. This seems to end up at a point in the
1092        generated configure script that is early enough to affect the setting of
1093        compiler options, which is what is needed, but I have no means of testing
1094        whether it really works. (The user who reported this had patched the
1095        generated configure script, which of course I cannot do.)
1097        LATER: After change 22 below (new libtool files), the configure script
1098        seems to know about icc (and also ecc). Therefore, I have commented out
1099        this hack in configure.in.
1101     7. Added support for pkg-config (2 patches were sent in).
1103     8. Negated POSIX character classes that used a combination of internal tables
1104        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1105        [[:^ascii]]. Typically, they would match almost any characters. The other
1106        POSIX classes were not broken in this way.
1108     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1109        to find the match, as PCRE was deluded into thinking that the match had to
1110        start at the start point or following a newline. The same bug applied to
1111        patterns with negative forward assertions or any backward assertions
1112        preceding ".*" at the start, unless the pattern required a fixed first
1113        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1115    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1116        starting at the last subject character, bytes beyond the end of the subject
1117        string were read.
1119    11. Renamed the variable "class" as "classbits" to make life easier for C++
1120        users. (Previously there was a macro definition, but it apparently wasn't
1121        enough.)
1123    12. Added the new field "tables" to the extra data so that tables can be passed
1124        in at exec time, or the internal tables can be re-selected. This allows
1125        a compiled regex to be saved and re-used at a later time by a different
1126        program that might have everything at different addresses.
1128    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1129        -R library as well as a -L library.
1131    14. The debugging options of pcretest (-d on the command line or D on a
1132        pattern) showed incorrect output for anything following an extended class
1133        that contained multibyte characters and which was followed by a quantifier.
1135    15. Added optional support for general category Unicode character properties
1136        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1137        support. It adds about 90K to the size of the library. The meanings of the
1138        inbuilt class escapes such as \d and \s have NOT been changed.
1140    16. Updated pcredemo.c to include calls to free() to release the memory for the
1141        compiled pattern.
1143    17. The generated file chartables.c was being created in the source directory
1144        instead of in the building directory. This caused the build to fail if the
1145        source directory was different from the building directory, and was
1146        read-only.
1148    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1149        file. No doubt somebody will tell me if they don't make sense... Also added
1150        Dan Mooney's comments about building on OpenVMS.
1152    19. Added support for partial matching via the PCRE_PARTIAL option for
1153        pcre_exec() and the \P data escape in pcretest.
1155    20. Extended pcretest with 3 new pattern features:
1157        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1158              write the compiled pattern to the file whose name is "rest-of-line".
1159              This is a straight binary dump of the data, with the saved pointer to
1160              the character tables forced to be NULL. The study data, if any, is
1161              written too. After writing, pcretest reads a new pattern.
1163        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1164              compiled pattern from the given file. There must not be any
1165              occurrences of "<" in the file name (pretty unlikely); if there are,
1166              pcretest will instead treat the initial "<" as a pattern delimiter.
1167              After reading in the pattern, pcretest goes on to read data lines as
1168              usual.
1170        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1171              and 16-bit fields in a compiled pattern, to simulate a pattern that
1172              was compiled on a host of opposite endianness.
1174    21. The pcre-exec() function can now cope with patterns that were compiled on
1175        hosts of opposite endianness, with this restriction:
1177          As for any compiled expression that is saved and used later, the tables
1178          pointer field cannot be preserved; the extra_data field in the arguments
1179          to pcre_exec() should be used to pass in a tables address if a value
1180          other than the default internal tables were used at compile time.
1182    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1183        now diagnosed as an error. Previously, most of the time, a negative number
1184        would have been treated as zero, but if in addition "ovector" was passed as
1185        NULL, a crash could occur.
1187    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1188        new versions from the libtool 1.5 distribution (the last one is a copy of
1189        a file called libtool.m4). This seems to have fixed the need to patch
1190        "configure" to support Darwin 1.3 (which I used to do). However, I still
1191        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1192        workstation).
1194    24. Changed the PCRE licence to be the more standard "BSD" licence.
1197    Version 4.5 01-Dec-03
1198    ---------------------
1200     1. There has been some re-arrangement of the code for the match() function so
1201        that it can be compiled in a version that does not call itself recursively.
1202        Instead, it keeps those local variables that need separate instances for
1203        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1204        needs to "recurse". Keeping track of where control must go is done by means
1205        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1206        hide most of the details from the main code, and operates only if
1207        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1208        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1209        operating.
1211        To make it easier for callers to provide specially tailored get/free
1212        functions for this usage, two new functions, pcre_stack_malloc, and
1213        pcre_stack_free, are used. They are always called in strict stacking order,
1214        and the size of block requested is always the same.
1216        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1217        PCRE has been compiled to use the stack or the heap for recursion. The
1218        -C option of pcretest uses this to show which version is compiled.
1220        A new data escape \S, is added to pcretest; it causes the amounts of store
1221        obtained and freed by both kinds of malloc/free at match time to be added
1222        to the output.
1224     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1225        what's available on my current Linux desktop machine.
1227     3. When matching a UTF-8 string, the test for a valid string at the start has
1228        been extended. If start_offset is not zero, PCRE now checks that it points
1229        to a byte that is the start of a UTF-8 character. If not, it returns
1230        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1231        this is necessary because there may be backward assertions in the pattern.
1232        When matching the same subject several times, it may save resources to use
1233        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1235     4. The code for checking the validity of UTF-8 strings has been tightened so
1236        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1237        containing "overlong sequences".
1239     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1240        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1241        should have been "&", but it just so happened that all the cases this let
1242        through by mistake were picked up later in the function.
1244     6. I had used a variable called "isblank" - this is a C99 function, causing
1245        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1247     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1248        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1249        so the version is shown; (c) stop "make test" echoing "./RunTest".
1251     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1253     9. The prototype for memmove() for systems that don't have it was using
1254        size_t, but the inclusion of the header that defines size_t was later. I've
1255        moved the #includes for the C headers earlier to avoid this.
1257    10. Added some adjustments to the code to make it easier to compiler on certain
1258        special systems:
1260          (a) Some "const" qualifiers were missing.
1261          (b) Added the macro EXPORT before all exported functions; by default this
1262              is defined to be empty.
1263          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1264              that it reads its output file name as an argument instead of writing
1265              to the standard output and assuming this can be redirected.
1267    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1268        class containing characters with values greater than 255, PCRE compilation
1269        went into a loop.
1271    12. A recursive reference to a subpattern that was within another subpattern
1272        that had a minimum quantifier of zero caused PCRE to crash. For example,
1273        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1274        recursion. If the recursively-called subpattern itself had a zero repeat,
1275        that was OK.
1277    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1278        buffer into which it was copied (for escape processing) was still set at
1279        1024, so long lines caused crashes.
1281    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1282        "internal error: code overflow...". This applied to any character class
1283        that was followed by a possessive quantifier.
1285    15. Modified the Makefile to add libpcre.la as a prerequisite for
1286        libpcreposix.la because I was told this is needed for a parallel build to
1287        work.
1289    16. If a pattern that contained .* following optional items at the start was
1290        studied, the wrong optimizing data was generated, leading to matching
1291        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1292        matching string must start with a or b or c. The correct conclusion for
1293        this pattern is that a match can start with any character.
1296    Version 4.4 13-Aug-03
1297    ---------------------
1299     1. In UTF-8 mode, a character class containing characters with values between
1300        127 and 255 was not handled correctly if the compiled pattern was studied.
1301        In fixing this, I have also improved the studying algorithm for such
1302        classes (slightly).
1304     2. Three internal functions had redundant arguments passed to them. Removal
1305        might give a very teeny performance improvement.
1307     3. Documentation bug: the value of the capture_top field in a callout is *one
1308        more than* the number of the hightest numbered captured substring.
1310     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1311        in incorrectly linking with a previously installed version. They now link
1312        explicitly with libpcre.la.
1314     5. configure.in no longer needs to recognize Cygwin specially.
1316     6. A problem in pcre.in for Windows platforms is fixed.
1318     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1319        pcretest, it used to include the size of the study block as part of its
1320        output. Unfortunately, the structure contains a field that has a different
1321        size on different hardware architectures. This meant that the tests that
1322        showed this size failed. As the block is currently always of a fixed size,
1323        this information isn't actually particularly useful in pcretest output, so
1324        I have just removed it.
1326     8. Three pre-processor statements accidentally did not start in column 1.
1327        Sadly, there are *still* compilers around that complain, even though
1328        standard C has not required this for well over a decade. Sigh.
1330     9. In pcretest, the code for checking callouts passed small integers in the
1331        callout_data field, which is a void * field. However, some picky compilers
1332        complained about the casts involved for this on 64-bit systems. Now
1333        pcretest passes the address of the small integer instead, which should get
1334        rid of the warnings.
1336    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1337        both compile and run time, and gives an error if an invalid UTF-8 sequence
1338        is found. There is a option for disabling this check in cases where the
1339        string is known to be correct and/or the maximum performance is wanted.
1341    11. In response to a bug report, I changed one line in Makefile.in from
1343            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1344        to
1345            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1347        to look similar to other lines, but I have no way of telling whether this
1348        is the right thing to do, as I do not use Windows. No doubt I'll get told
1349        if it's wrong...
1352    Version 4.3 21-May-03
1353    ---------------------
1355    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1356       Makefile.
1358    2. Some refactoring to improve the quality of the code:
1360       (i)   The utf8_table... variables are now declared "const".
1362       (ii)  The code for \cx, which used the "case flipping" table to upper case
1363             lower case letters, now just substracts 32. This is ASCII-specific,
1364             but the whole concept of \cx is ASCII-specific, so it seems
1365             reasonable.
1367       (iii) PCRE was using its character types table to recognize decimal and
1368             hexadecimal digits in the pattern. This is silly, because it handles
1369             only 0-9, a-f, and A-F, but the character types table is locale-
1370             specific, which means strange things might happen. A private
1371             table is now used for this - though it costs 256 bytes, a table is
1372             much faster than multiple explicit tests. Of course, the standard
1373             character types table is still used for matching digits in subject
1374             strings against \d.
1376       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1377             ending in _t are). So I've renamed it as ESC_tee.
1379    3. The first argument for regexec() in the POSIX wrapper should have been
1380       defined as "const".
1382    4. Changed pcretest to use malloc() for its buffers so that they can be
1383       Electric Fenced for debugging.
1385    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1386       to read one or more bytes before the start of the subject string. Often this
1387       had no effect on PCRE's behaviour, but in some circumstances it could
1388       provoke a segmentation fault.
1390    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1391       to try to read one or more bytes before the start of the subject string.
1393    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1394       UTF-8 support could misbehave in various ways if the subject string
1395       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1396       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1397       back over UTF-8 characters.)
1400    Version 4.2 14-Apr-03
1401    ---------------------
1403    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1405    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1406         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1407         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1408         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1409         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1410           and BUILD_EXEEXT
1411         Note: automatic setting of the BUILD variables is not yet working
1412         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1413           compile-time but not at link-time
1414         [LINK]: use for linking executables only
1415         make different versions for Windows and non-Windows
1416         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1417           libraries
1418         [LINK_FOR_BUILD]: new variable
1419         [OBJEXT]: use throughout
1420         [EXEEXT]: use throughout
1421         <winshared>: new target
1422         <wininstall>: new target
1423         <dftables.o>: use native compiler
1424         <dftables>: use native linker
1425         <install>: handle Windows platform correctly
1426         <clean>: ditto
1427         <check>: ditto
1428         copy DLL to top builddir before testing
1430       As part of these changes, -no-undefined was removed again. This was reported
1431       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1432       in any case.
1434    3. Some tidies to get rid of compiler warnings:
1436       . In the match_data structure, match_limit was an unsigned long int, whereas
1437         match_call_count was an int. I've made them both unsigned long ints.
1439       . In pcretest the fact that a const uschar * doesn't automatically cast to
1440         a void * provoked a warning.
1442       . Turning on some more compiler warnings threw up some "shadow" variables
1443         and a few more missing casts.
1445    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1446       option, a class that contained a single character with a value between 128
1447       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1449    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1450       option, a class that contained several characters, but with at least one
1451       whose value was between 128 and 255 caused PCRE to crash.
1454    Version 4.1 12-Mar-03
1455    ---------------------
1457    1. Compiling with gcc -pedantic found a couple of places where casts were
1458    needed, and a string in dftables.c that was longer than standard compilers are
1459    required to support.
1461    2. Compiling with Sun's compiler found a few more places where the code could
1462    be tidied up in order to avoid warnings.
1464    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1465    first of these names is deprecated in the latest Autoconf in favour of the name
1466    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1467    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1468    analogy I have changed it to CFLAGS_FOR_BUILD.
1470    4. Added -no-undefined to the linking command in the Makefile, because this is
1471    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1472    linking step for the pcreposix library.
1474    5. PCRE was failing to diagnose the case of two named groups with the same
1475    name.
1477    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1478    literal character that is needed in the subject for a match, and scans along to
1479    ensure that it is present before embarking on the full matching process. This
1480    saves time in cases of nested unlimited repeats that are never going to match.
1481    Problem: the scan can take a lot of time if the subject is very long (e.g.
1482    megabytes), thus penalizing straightforward matches. It is now done only if the
1483    amount of subject to be scanned is less than 1000 bytes.
1485    7. A lesser problem with the same optimization is that it was recording the
1486    first character of an anchored pattern as "needed", thus provoking a search
1487    right along the subject, even when the first match of the pattern was going to
1488    fail. The "needed" character is now not set for anchored patterns, unless it
1489    follows something in the pattern that is of non-fixed length. Thus, it still
1490    fulfils its original purpose of finding quick non-matches in cases of nested
1491    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1494    Version 4.0 17-Feb-03
1495    ---------------------
1497    1. If a comment in an extended regex that started immediately after a meta-item
1498    extended to the end of string, PCRE compiled incorrect data. This could lead to
1499    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1501    2. Moved to autoconf 2.53 and libtool 1.4.2.
1503    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1504    the special perltest8 script is no longer needed - all the tests can be run
1505    from a single perltest script.
1507    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1508    by \s. It has now been removed in PCRE. This means it isn't recognized as
1509    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1510    class [:space:] *does* include VT, thereby creating a mess.
1512    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1513    space and tab.
1515    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1516    its new features into the main test script, reducing the number of scripts.
1518    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1519    were backward compatible, and made the (?i) apply to the whole pattern, as if
1520    /i were given. Now it behaves more logically, and applies the option setting
1521    only to what follows. PCRE has been changed to follow suit. However, if it
1522    finds options settings right at the start of the pattern, it extracts them into
1523    the global options, as before. Thus, they show up in the info data.
1525    8. Added support for the \Q...\E escape sequence. Characters in between are
1526    treated as literals. This is slightly different from Perl in that $ and @ are
1527    also handled as literals inside the quotes. In Perl, they will cause variable
1528    interpolation. Note the following examples:
1530        Pattern            PCRE matches      Perl matches
1532        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1533        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1534        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1536    For compatibility with Perl, \Q...\E sequences are recognized inside character
1537    classes as well as outside them.
1539    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1540    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1541    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1542    signed/unsigned warnings.
1544    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1545    option for pcretest, so I've replaced it by a simple function that does just
1546    that job.
1548    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1549    "pcregrep -".
1551    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1552    Java package. This provides some syntactic sugar for simple cases of what my
1553    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1554    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1555    item, you can use this simplified notation. Note that only makes sense with
1556    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1557    greediness, whatever the setting of the PCRE_UNGREEDY option.
1559    13. A change of greediness default within a pattern was not taking effect at
1560    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1561    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1562    was abstracted outside.
1564    14. PCRE now supports the \G assertion. It is true when the current matching
1565    position is at the start point of the match. This differs from \A when the
1566    starting offset is non-zero. Used with the /g option of pcretest (or similar
1567    code), it works in the same way as it does for Perl's /g option. If all
1568    alternatives of a regex begin with \G, the expression is anchored to the start
1569    match position, and the "anchored" flag is set in the compiled expression.
1571    15. Some bugs concerning the handling of certain option changes within patterns
1572    have been fixed. These applied to options other than (?ims). For example,
1573    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1574    been the other way round. Some of this was related to change 7 above.
1576    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1577    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1578    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1579    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1581    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1582    mode. Unlike ".", it always matches newline, whatever the setting of
1583    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1584    assertions. Perl allows it, but it doesn't (in general) work because it can't
1585    calculate the length of the lookbehind. At least, that's the case for Perl
1586    5.8.0 - I've been told they are going to document that it doesn't work in
1587    future.
1589    18. Added an error diagnosis for escapes that PCRE does not support: these are
1590    \L, \l, \N, \P, \p, \U, \u, and \X.
1592    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1593    reading past the end of the pattern in cases such as /[abcd/.
1595    20. PCRE was getting more memory than necessary for patterns with classes that
1596    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1598    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1599    compiling PCRE for use with Virtual Pascal.
1601    22. Small fix to the Makefile to make it work properly if the build is done
1602    outside the source tree.
1604    23. Added a new extension: a condition to go with recursion. If a conditional
1605    subpattern starts with (?(R) the "true" branch is used if recursion has
1606    happened, whereas the "false" branch is used only at the top level.
1608    24. When there was a very long string of literal characters (over 255 bytes
1609    without UTF support, over 250 bytes with UTF support), the computation of how
1610    much memory was required could be incorrect, leading to segfaults or other
1611    strange effects.
1613    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1614    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1615    there was a subsequent back reference to those brackets. This meant that, for
1616    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1617    possible to check for precisely this case. All we can do is abandon the
1618    optimization if .* occurs inside capturing brackets when there are any back
1619    references whatsoever. (See below for a better fix that came later.)
1621    26. The handling of the optimization for finding the first character of a
1622    non-anchored pattern, and for finding a character that is required later in the
1623    match were failing in some cases. This didn't break the matching; it just
1624    failed to optimize when it could. The way this is done has been re-implemented.
1626    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1628    28. Added a new feature that provides some of the functionality that Perl
1629    provides with (?{...}). The facility is termed a "callout". The way it is done
1630    in PCRE is for the caller to provide an optional function, by setting
1631    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1632    global variable. By default it is unset, which disables all calling out. To get
1633    the function called, the regex must include (?C) at appropriate points. This
1634    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1635    This provides a means of identifying different callout points. When PCRE
1636    reaches such a point in the regex, if pcre_callout has been set, the external
1637    function is called. It is provided with data in a structure called
1638    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1639    matching continues; if it returns a non-zero value, the match at the current
1640    point fails. However, backtracking will occur if possible. [This was changed
1641    later and other features added - see item 49 below.]
1643    29. pcretest is upgraded to test the callout functionality. It provides a
1644    callout function that displays information. By default, it shows the start of
1645    the match and the current position in the text. There are some new data escapes
1646    to vary what happens:
1648        \C+         in addition, show current contents of captured substrings
1649        \C-         do not supply a callout function
1650        \C!n        return 1 when callout number n is reached
1651        \C!n!m      return 1 when callout number n is reached for the mth time
1653    30. If pcregrep was called with the -l option and just a single file name, it
1654    output "<stdin>" if a match was found, instead of the file name.
1656    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1657    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1658    pcre_exec(). This saves a malloc/free per call. The default value of
1659    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1660    when configuring.
1662    32. The default maximum size of a compiled pattern is 64K. There have been a
1663    few cases of people hitting this limit. The code now uses macros to handle the
1664    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1665    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1666    configuring. Tests 2 and 5 work only with 2-byte links because they output
1667    debugging information about compiled patterns.
1669    33. Internal code re-arrangements:
1671    (a) Moved the debugging function for printing out a compiled regex into
1672        its own source file (printint.c) and used #include to pull it into
1673        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1674        separate copies.
1676    (b) Defined the list of op-code names for debugging as a macro in
1677        internal.h so that it is next to the definition of the opcodes.
1679    (c) Defined a table of op-code lengths for simpler skipping along compiled
1680        code. This is again a macro in internal.h so that it is next to the
1681        definition of the opcodes.
1683    34. Added support for recursive calls to individual subpatterns, along the
1684    lines of Robin Houston's patch (but implemented somewhat differently).
1686    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1687    allow it to read and process whole directories in Win32. This code was
1688    contributed by Lionel Fourquaux; it has not been tested by me.
1690    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1691    used to name a group. Names consist of alphanumerics and underscores, and must
1692    be unique. Back references use the syntax (?P=name) and recursive calls use
1693    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1694    numbers. The function pcre_fullinfo() can be used after compilation to extract
1695    a name/number map. There are three relevant calls:
1697      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1698      PCRE_INFO_NAMECOUNT            yields the number of entries
1699      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1701    The map is a vector of fixed-size entries. The size of each entry depends on
1702    the length of the longest name used. The first two bytes of each entry are the
1703    group number, most significant byte first. There follows the corresponding
1704    name, zero terminated. The names are in alphabetical order.
1706    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1707    case instead of 255. Making it the same both with and without UTF-8 support
1708    means that the same test output works with both.
1710    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1711    calling malloc() with a zero argument.
1713    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1714    optimization. I've improved things by keeping a bitmap of backreferences with
1715    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1716    fact referenced, the optimization can be applied. It is unlikely that a
1717    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1718    the match to follow \n) will appear inside brackets with a number greater than
1719    31, but if it does, any back reference > 31 suppresses the optimization.
1721    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1722    of disabling numbered capturing parentheses. Any opening parenthesis that is
1723    not followed by ? behaves as if it were followed by ?: but named parentheses
1724    can still be used for capturing (and they will acquire numbers in the usual
1725    way).
1727    41. Redesigned the return codes from the match() function into yes/no/error so
1728    that errors can be passed back from deep inside the nested calls. A malloc
1729    failure while inside a recursive subpattern call now causes the
1730    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1732    42. It is now possible to set a limit on the number of times the match()
1733    function is called in a call to pcre_exec(). This facility makes it possible to
1734    limit the amount of recursion and backtracking, though not in a directly
1735    obvious way, because the match() function is used in a number of different
1736    circumstances. The count starts from zero for each position in the subject
1737    string (for non-anchored patterns). The default limit is, for compatibility, a
1738    large number, namely 10 000 000. You can change this in two ways:
1740    (a) When configuring PCRE before making, you can use --with-match-limit=n
1741        to set a default value for the compiled library.
1743    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1744        a different value is set. See 45 below.
1746    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1748    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1749    of things that can be changed at compile time. The first argument specifies
1750    what is wanted and the second points to where the information is to be placed.
1751    The current list of available information is:
1753      PCRE_CONFIG_UTF8
1755    The output is an integer that is set to one if UTF-8 support is available;
1756    otherwise it is set to zero.
1760    The output is an integer that it set to the value of the code that is used for
1761    newline. It is either LF (10) or CR (13).
1765    The output is an integer that contains the number of bytes used for internal
1766    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1770    The output is an integer that contains the threshold above which the POSIX
1771    interface uses malloc() for output vectors. See item 31 above.
1775    The output is an unsigned integer that contains the default limit of the number
1776    of match() calls in a pcre_exec() execution. See 42 above.
1778    44. pcretest has been upgraded by the addition of the -C option. This causes it
1779    to extract all the available output from the new pcre_config() function, and to
1780    output it. The program then exits immediately.
1782    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1783    order to support additional features. One way would have been to define
1784    pcre_exec2() (for example) with extra arguments, but this would not have been
1785    extensible, and would also have required all calls to the original function to
1786    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1787    is used for passing in "extra" data from pcre_study().
1789    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1790    contains the following fields:
1792      flags         a bitmap indicating which of the following fields are set
1793      study_data    opaque data from pcre_study()
1794      match_limit   a way of specifying a limit on match() calls for a specific
1795                      call to pcre_exec()
1796      callout_data  data for callouts (see 49 below)
1798    The flag bits are also defined in pcre.h, and are
1804    The pcre_study() function now returns one of these new pcre_extra blocks, with
1805    the actual study data pointed to by the study_data field, and the
1806    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1807    before. That is, this change is entirely upwards-compatible and requires no
1808    change to existing code.
1810    If you want to pass in additional data to pcre_exec(), you can either place it
1811    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1812    block.
1814    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1815    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1816    times with different match limits, until it finds the minimum value needed for
1817    pcre_exec() to complete. The value is then output. This can be instructive; for
1818    most simple matches the number is quite small, but for pathological cases it
1819    gets very large very quickly.
1821    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1822    returns the size of the data block pointed to by the study_data field in a
1823    pcre_extra block, that is, the value that was passed as the argument to
1824    pcre_malloc() when PCRE was getting memory in which to place the information
1825    created by pcre_study(). The fourth argument should point to a size_t variable.
1826    pcretest has been extended so that this information is shown after a successful
1827    pcre_study() call when information about the compiled regex is being displayed.
1829    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1830    because what follows is always an absolute path. (Later: it turns out that this
1831    is more than cosmetic for MinGW, because it doesn't like empty path
1832    components.)
1834    49. Some changes have been made to the callout feature (see 28 above):
1836    (i)  A callout function now has three choices for what it returns:
1838           0  =>  success, carry on matching
1839         > 0  =>  failure at this point, but backtrack if possible
1840         < 0  =>  serious error, return this value from pcre_exec()
1842         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1843         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1844         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1845         use by callout functions. It will never be used by PCRE itself.
1847    (ii) The pcre_extra structure (see 45 above) has a void * field called
1848         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1849         pcre_callout_block structure has a field of the same name. The contents of
1850         the field passed in the pcre_extra structure are passed to the callout
1851         function in the corresponding field in the callout block. This makes it
1852         easier to use the same callout-containing regex from multiple threads. For
1853         testing, the pcretest program has a new data escape
1855           \C*n        pass the number n (may be negative) as callout_data
1857         If the callout function in pcretest receives a non-zero value as
1858         callout_data, it returns that value.
1860    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1861    there were some redundant $(CFLAGS) in commands that are now specified as
1862    $(LINK), which already includes $(CFLAGS).
1864    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1865    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1866    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1867    one-byte characters throughout. Note that case-insensitive matching applies
1868    only to characters whose values are less than 256. PCRE doesn't support the
1869    notion of cases for higher-valued characters.
1871    (i)   A character class whose characters are all within 0-255 is handled as
1872          a bit map, and the map is inverted for negative classes. Previously, a
1873          character > 255 always failed to match such a class; however it should
1874          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1876    (ii)  A negated character class with a single character < 255 is coded as
1877          "not this character" (OP_NOT). This wasn't working properly when the test
1878          character was multibyte, either singly or repeated.
1880    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1881          mode, for example: \x{100}{2,3}.
1883    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1884          singly or repeated) now correctly test multibyte characters. However,
1885          PCRE doesn't recognize any characters with values greater than 255 as
1886          digits, spaces, or word characters. Such characters always match \D, \S,
1887          and \W, and never match \d, \s, or \w.
1889    (v)   Classes may now contain characters and character ranges with values
1890          greater than 255. For example: [ab\x{100}-\x{400}].
1892    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1893          PCRE in UTF-8 mode.
1895    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1896    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1897    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1898    value.)
1900    53. The single man page has become too large. I have therefore split it up into
1901    a number of separate man pages. These also give rise to individual HTML pages;
1902    these are now put in a separate directory, and there is an index.html page that
1903    lists them all. Some hyperlinking between the pages has been installed.
1905    54. Added convenience functions for handling named capturing parentheses.
1907    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1908    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1909    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1910    are faulted.
1912    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1913    calling configure. These values are used when compiling the dftables.c program
1914    which is run to generate the source of the default character tables. They
1915    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1916    you will need to set these values.
1918    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1921    Version 3.9 02-Jan-02
1922    ---------------------
1924    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1926    2. If --disable-static was given, the building process failed when trying to
1927    build pcretest and pcregrep. (For some reason it was using libtool to compile
1928    them, which is not right, as they aren't part of the library.)
1931    Version 3.8 18-Dec-01
1932    ---------------------
1934    1. The experimental UTF-8 code was completely screwed up. It was packing the
1935    bytes in the wrong order. How dumb can you get?
1938    Version 3.7 29-Oct-01
1939    ---------------------
1941    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1942    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1943    this didn't happen under Solaris 8, where I normally test things.
1945    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1946    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1947    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1948    this fix an hour or so after the initial 3.7 release.)
1951    Version 3.6 23-Oct-01
1952    ---------------------
1954    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1955    offsets passed as NULL with zero offset count.
1957    2. The config.guess and config.sub files had not been updated when I moved to
1958    the latest autoconf.
1961    Version 3.5 15-Aug-01
1962    ---------------------
1964    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1965    had been forgotten.
1967    2. By using declared but undefined structures, we can avoid using "void"
1968    definitions in pcre.h while keeping the internal definitions of the structures
1969    private.
1971    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1972    user point of view, this means that both static and shared libraries are built
1973    by default, but this can be individually controlled. More of the work of
1974    handling this static/shared cases is now inside libtool instead of PCRE's make
1975    file.
1977    4. The pcretest utility is now installed along with pcregrep because it is
1978    useful for users (to test regexs) and by doing this, it automatically gets
1979    relinked by libtool. The documentation has been turned into a man page, so
1980    there are now .1, .txt, and .html versions in /doc.
1982    5. Upgrades to pcregrep:
1983       (i)   Added long-form option names like gnu grep.
1984       (ii)  Added --help to list all options with an explanatory phrase.
1985       (iii) Added -r, --recursive to recurse into sub-directories.
1986       (iv)  Added -f, --file to read patterns from a file.
1988    6. pcre_exec() was referring to its "code" argument before testing that
1989    argument for NULL (and giving an error if it was NULL).
1991    7. Upgraded Makefile.in to allow for compiling in a different directory from
1992    the source directory.
1994    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1995    options bits, the pointer it was passed was to an int instead of to an unsigned
1996    long int. This mattered only on 64-bit systems.
1998    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1999    generated) instead of pcre.in, which it its source. Also made the same change
2000    in several of the .c files.
2002    10. A new release of gcc defines printf() as a macro, which broke pcretest
2003    because it had an ifdef in the middle of a string argument for printf(). Fixed
2004    by using separate calls to printf().
2006    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2007    script, to force use of CR or LF instead of \n in the source. On non-Unix
2008    systems, the value can be set in config.h.
2010    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2011    absolute limit. Changed the text of the error message to make this clear, and
2012    likewise updated the man page.
2014    13. The limit of 99 on the number of capturing subpatterns has been removed.
2015    The new limit is 65535, which I hope will not be a "real" limit.
2018    Version 3.4 22-Aug-00
2019    ---------------------
2021    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2023    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2026    Version 3.3 01-Aug-00
2027    ---------------------
2029    1. If an octal character was given, but the value was greater than \377, it
2030    was not getting masked to the least significant bits, as documented. This could
2031    lead to crashes in some systems.
2033    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2034    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2036    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2037    These just pass their arguments on to (pcre_free)(), but they are provided
2038    because some uses of PCRE bind it to non-C systems that can call its functions,
2039    but cannot call free() or pcre_free() directly.
2041    4. Add "make test" as a synonym for "make check". Corrected some comments in
2042    the Makefile.
2044    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2045    Makefile.
2047    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2048    command called pgrep for grepping around the active processes.
2050    7. Added the beginnings of support for UTF-8 character strings.
2052    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2053    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2054    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2055    out for the ar command.)
2058    Version 3.2 12-May-00
2059    ---------------------
2061    This is purely a bug fixing release.
2063    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2064    of ZA. This was just one example of several cases that could provoke this bug,
2065    which was introduced by change 9 of version 2.00. The code for breaking
2066    infinite loops after an iteration that matches an empty string was't working
2067    correctly.
2069    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2070    when matched against abbab (for example). After matching an empty string, it
2071    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2072    caused it to match further down the string than it should.
2074    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2075    was there because it doesn't seem to be needed, and it causes trouble on some
2076    systems, as it is not a Standard C header. It has been removed.
2078    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2079    were reported on the Macintosh. The changes were from
2081      while ((c = *(++ptr)) != 0 && c != '\n');
2082    to
2083      while ((c = *(++ptr)) != 0 && c != '\n') ;
2085    Totally extraordinary, but if that's what it takes...
2087    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2088    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2089    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2090    assumes the way PCRE uses memmove() (always moving upwards).
2092    6. PCRE is being used in one environment where strchr() is not available. There
2093    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2094    faster code anyway.
2097    Version 3.1 09-Feb-00
2098    ---------------------
2100    The only change in this release is the fixing of some bugs in Makefile.in for
2101    the "install" target:
2103    (1) It was failing to install pcreposix.h.
2105    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2108    Version 3.0 01-Feb-00
2109    ---------------------
2111    1. Add support for the /+ modifier to perltest (to output $` like it does in
2112    pcretest).
2114    2. Add support for the /g modifier to perltest.
2116    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2117    matches null strings.
2119    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2120    pattern. Perl treats empty patterns specially - it reuses the most recent
2121    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2122    effect.
2124    5. The POSIX interface was broken in that it was just handing over the POSIX
2125    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2126    required a bigger vector, with some working space on the end. This means that
2127    the POSIX wrapper now has to get and free some memory, and copy the results.
2129    6. Added some simple autoconf support, placing the test data and the
2130    documentation in separate directories, re-organizing some of the
2131    information files, and making it build pcre-config (a GNU standard). Also added
2132    libtool support for building PCRE as a shared library, which is now the
2133    default.
2135    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2136    09 are not valid octal constants. Single digits will be used for minor values
2137    less than 10.
2139    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2140    existing programs that set these in the POSIX interface can use PCRE without
2141    modification.
2143    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2144    return all that pcre_info() returns, plus additional data. The pcre_info()
2145    function is retained for compatibility, but is considered to be obsolete.
2147    10. Added experimental recursion feature (?R) to handle one common case that
2148    Perl 5.6 will be able to do with (?p{...}).
2150    11. Added support for POSIX character classes like [:alpha:], which Perl is
2151    adopting.
2154    Version 2.08 31-Aug-99
2155    ----------------------
2157    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2158    trying to match at the startoffset position, but instead was moving forward to
2159    the next newline as if a previous match had failed.
2161    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2162    and could get into a loop if a null string was matched other than at the start
2163    of the subject.
2165    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2166    be distinguished at compile time, and for completeness also added PCRE_DATE.
2168    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2169    in GnuWin32 environments.
2172    Version 2.07 29-Jul-99
2173    ----------------------
2175    1. The documentation is now supplied in plain text form and HTML as well as in
2176    the form of man page sources.
2178    2. C++ compilers don't like assigning (void *) values to other pointer types.
2179    In particular this affects malloc(). Although there is no problem in Standard
2180    C, I've put in casts to keep C++ compilers happy.
2182    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2183    should be (const char *).
2185    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2186    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2187    However, I haven't made this a standard facility. The documentation doesn't
2188    mention it, and the Makefile doesn't support it.
2190    5. The Makefile now contains an "install" target, with editable destinations at
2191    the top of the file. The pcretest program is not installed.
2193    6. pgrep -V now gives the PCRE version number and date.
2195    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2196    causing the entire string to be ignored, instead of just the last character.
2198    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2199    non-matching string, it can take a very, very long time, even for strings of
2200    quite modest length, because of the nested recursion. PCRE now does better in
2201    some of these cases. It does this by remembering the last required literal
2202    character in the pattern, and pre-searching the subject to ensure it is present
2203    before running the real match. In other words, it applies a heuristic to detect
2204    some types of certain failure quickly, and in the above example, if presented
2205    with a string that has no trailing " it gives "no match" very quickly.
2207    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2208    other alternatives are tried instead.
2211    Version 2.06 09-Jun-99
2212    ----------------------
2214    1. Change pcretest's output for amount of store used to show just the code
2215    space, because the remainder (the data block) varies in size between 32-bit and
2216    64-bit systems.
2218    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2219    start matching at. This allows lookbehinds to work when searching for multiple
2220    occurrences in a string.
2222    3. Added additional options to pcretest for testing multiple occurrences:
2224       /+   outputs the rest of the string that follows a match
2225       /g   loops for multiple occurrences, using the new startoffset argument
2226       /G   loops for multiple occurrences by passing an incremented pointer
2228    4. PCRE wasn't doing the "first character" optimization for patterns starting
2229    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2230    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2231    the letter 'x'. On long subject strings, this gives a significant speed-up.
2234    Version 2.05 21-Apr-99
2235    ----------------------
2237    1. Changed the type of magic_number from int to long int so that it works
2238    properly on 16-bit systems.
2240    2. Fixed a bug which caused patterns starting with .* not to work correctly
2241    when the subject string contained newline characters. PCRE was assuming
2242    anchoring for such patterns in all cases, which is not correct because .* will
2243    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2244    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2245    must be retried after every newline in the subject.
2248    Version 2.04 18-Feb-99
2249    ----------------------
2251    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2252    computation of the store needed to hold the pattern was incorrect (too large).
2253    If such patterns were nested a few deep, this could multiply and become a real
2254    problem.
2256    2. Added /M option to pcretest to show the memory requirement of a specific
2257    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2259    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2260    compiled in such a way that the backtracking after subsequent failure was
2261    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2262    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2265    Version 2.03 02-Feb-99
2266    ----------------------
2268    1. Fixed typo and small mistake in man page.
2270    2. Added 4th condition (GPL supersedes if conflict) and created separate
2271    LICENCE file containing the conditions.
2273    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2274    Perl, that is the internal \ allows the delimiter to be included in the
2275    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2276    the final delimiter, add \ to the end of the pattern (to test the error).
2278    4. Added the convenience functions for extracting substrings after a successful
2279    match. Updated pcretest to make it able to test these functions.
2282    Version 2.02 14-Jan-99
2283    ----------------------
2285    1. Initialized the working variables associated with each extraction so that
2286    their saving and restoring doesn't refer to uninitialized store.
2288    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2289    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2290    fix the problem.
2292    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2293    calls, and wasn't printing the correct value for compiling calls. Increased the
2294    default value of LOOPREPEAT, and the number of significant figures in the
2295    times.
2297    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2299    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2300    a building problem on Windows NT with a FAT file system.
2303    Version 2.01 21-Oct-98
2304    ----------------------
2306    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2307    to character tables built by pcre_maketables() in the current locale. If NULL
2308    is passed, the default tables are used.
2311    Version 2.00 24-Sep-98
2312    ----------------------
2314    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2315    it any more.
2317    2. Allow quantification of (?>) groups, and make it work correctly.
2319    3. The first character computation wasn't working for (?>) groups.
2321    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2322    end of the subject) and add 5.005's \z, which really does match only at the
2323    very end of the subject.
2325    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2327    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2328    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2329    localized options. All options to pcre_study() were also removed.
2331    7. Add other new features from 5.005:
2333       $(?<=           positive lookbehind
2334       $(?<!           negative lookbehind
2335       (?imsx-imsx)    added the unsetting capability
2336                       such a setting is global if at outer level; local otherwise
2337       (?imsx-imsx:)   non-capturing groups with option setting
2338       (?(cond)re|re)  conditional pattern matching
2340       A backreference to itself in a repeated group matches the previous
2341       captured string.
2343    8. General tidying up of studying (both automatic and via "study")
2344    consequential on the addition of new assertions.
2346    9. As in 5.005, unlimited repeated groups that could match an empty substring
2347    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2348    runtime if any iteration does actually match an empty substring.
2350    10. Include the RunTest script in the distribution.
2352    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2353    discrepancies, some of which were old and were also with respect to 5.004. They
2354    have now been fixed.
2357    Version 1.09 28-Apr-98
2358    ----------------------
2360    1. A negated single character class followed by a quantifier with a minimum
2361    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2362    program crashes, or just wrong answers. This did not apply to negated classes
2363    containing more than one character, or to minima other than one.
2366  Version 1.08 27-Mar-98  Version 1.08 27-Mar-98
2367  ----------------------  ----------------------

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