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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 05-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 maintain/132html script that I use to
25        generate HTML has been updated to handle .nf/.fi and to complain if it
26        encounters .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, for the benefit
30        of those who have to compile without Autotools (compare pcre.h).
32     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
33        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
34        makevp.bat for the current PCRE, using the additional files !compile.txt,
35        !linklib.txt, and pcregexp.pas.
38    Version 7.0 19-Dec-06
39    ---------------------
41     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
42        moving to gcc 4.1.1.
44     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
45        sys/time.h, which is documented as needed for this function. It doesn't
46        seem to matter on Linux, but it showed up on some releases of OS X.
48     3. It seems that there are systems where bytes whose values are greater than
49        127 match isprint() in the "C" locale. The "C" locale should be the
50        default when a C program starts up. In most systems, only ASCII printing
51        characters match isprint(). This difference caused the output from pcretest
52        to vary, making some of the tests fail. I have changed pcretest so that:
54        (a) When it is outputting text in the compiled version of a pattern, bytes
55            other than 32-126 are always shown as hex escapes.
57        (b) When it is outputting text that is a matched part of a subject string,
58            it does the same, unless a different locale has been set for the match
59            (using the /L modifier). In this case, it uses isprint() to decide.
61     4. Fixed a major bug that caused incorrect computation of the amount of memory
62        required for a compiled pattern when options that changed within the
63        pattern affected the logic of the preliminary scan that determines the
64        length. The relevant options are -x, and -i in UTF-8 mode. The result was
65        that the computed length was too small. The symptoms of this bug were
66        either the PCRE error "internal error: code overflow" from pcre_compile(),
67        or a glibc crash with a message such as "pcretest: free(): invalid next
68        size (fast)". Examples of patterns that provoked this bug (shown in
69        pcretest format) are:
71          /(?-x: )/x
72          /(?x)(?-x: \s*#\s*)/
73          /((?i)[\x{c0}])/8
74          /(?i:[\x{c0}])/8
76        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
77        is now done differently.
79     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
80        wrapper classes; (b) implement a new function in the C++ scanner that is
81        more efficient than the old way of doing things because it avoids levels of
82        recursion in the regex matching; (c) add a paragraph to the documentation
83        for the FullMatch() function.
85     6. The escape sequence \n was being treated as whatever was defined as
86        "newline". Not only was this contrary to the documentation, which states
87        that \n is character 10 (hex 0A), but it also went horribly wrong when
88        "newline" was defined as CRLF. This has been fixed.
90     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
91        was being set to -1 for the "end of line" case (supposedly a value that no
92        character can have). Though this value is never used (the check for end of
93        line is "zero bytes in current character"), it caused compiler complaints.
94        I've changed it to 0xffffffff.
96     8. In pcre_version.c, the version string was being built by a sequence of
97        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
98        string (as it is for production releases) called a macro with an empty
99        argument. The C standard says the result of this is undefined. The gcc
100        compiler treats it as an empty string (which was what was wanted) but it is
101        reported that Visual C gives an error. The source has been hacked around to
102        avoid this problem.
104     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
105        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
106        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
107        of them did).
109    10. Originally, pcretest opened its input and output without "b"; then I was
110        told that "b" was needed in some environments, so it was added for release
111        5.0 to both the input and output. (It makes no difference on Unix-like
112        systems.) Later I was told that it is wrong for the input on Windows. I've
113        now abstracted the modes into two macros, to make it easier to fiddle with
114        them, and removed "b" from the input mode under Windows.
116    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
118    12. Added -help and --help to pcretest as an official way of being reminded
119        of the options.
121    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
122        and pcrecpp.cc because they annoy compilers at high warning levels.
124    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
126    15. Fixed an occurrence of == in configure.ac that should have been = (shell
127        scripts are not C programs :-) and which was not noticed because it works
128        on Linux.
130    16. pcretest is supposed to handle any length of pattern and data line (as one
131        line or as a continued sequence of lines) by extending its input buffer if
132        necessary. This feature was broken for very long pattern lines, leading to
133        a string of junk being passed to pcre_compile() if the pattern was longer
134        than about 50K.
136    17. I have done a major re-factoring of the way pcre_compile() computes the
137        amount of memory needed for a compiled pattern. Previously, there was code
138        that made a preliminary scan of the pattern in order to do this. That was
139        OK when PCRE was new, but as the facilities have expanded, it has become
140        harder and harder to keep it in step with the real compile phase, and there
141        have been a number of bugs (see for example, 4 above). I have now found a
142        cunning way of running the real compile function in a "fake" mode that
143        enables it to compute how much memory it would need, while actually only
144        ever using a few hundred bytes of working memory and without too many
145        tests of the mode. This should make future maintenance and development
146        easier. A side effect of this work is that the limit of 200 on the nesting
147        depth of parentheses has been removed (though this was never a serious
148        limitation, I suspect). However, there is a downside: pcre_compile() now
149        runs more slowly than before (30% or more, depending on the pattern). I
150        hope this isn't a big issue. There is no effect on runtime performance.
152    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
153        newline (only possible for the last line of a file) and it was a
154        pattern that set a locale (followed by /Lsomething), pcretest crashed.
156    19. Added additional timing features to pcretest. (1) The -tm option now times
157        matching only, not compiling. (2) Both -t and -tm can be followed, as a
158        separate command line item, by a number that specifies the number of
159        repeats to use when timing. The default is 50000; this gives better
160        precision, but takes uncomfortably long for very large patterns.
162    20. Extended pcre_study() to be more clever in cases where a branch of a
163        subpattern has no definite first character. For example, (a*|b*)[cd] would
164        previously give no result from pcre_study(). Now it recognizes that the
165        first character must be a, b, c, or d.
167    21. There was an incorrect error "recursive call could loop indefinitely" if
168        a subpattern (or the entire pattern) that was being tested for matching an
169        empty string contained only one non-empty item after a nested subpattern.
170        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
171        incorrectly, because the \d was being skipped in the check.
173    22. The pcretest program now has a new pattern option /B and a command line
174        option -b, which is equivalent to adding /B to every pattern. This causes
175        it to show the compiled bytecode, without the additional information that
176        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
177        is the same as /B/I).
179    23. A new optimization is now able automatically to treat some sequences such
180        as a*b as a*+b. More specifically, if something simple (such as a character
181        or a simple class like \d) has an unlimited quantifier, and is followed by
182        something that cannot possibly match the quantified thing, the quantifier
183        is automatically "possessified".
185    24. A recursive reference to a subpattern whose number was greater than 39
186        went wrong under certain circumstances in UTF-8 mode. This bug could also
187        have affected the operation of pcre_study().
189    25. Realized that a little bit of performance could be had by replacing
190        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
192    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
194    27. Possessive quantifiers such as a++ were previously implemented by turning
195        them into atomic groups such as ($>a+). Now they have their own opcodes,
196        which improves performance. This includes the automatically created ones
197        from 23 above.
199    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
200        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
201        the first matched character to be a colon. This applied both to named and
202        numbered groups.
204    29. The ucpinternal.h header file was missing its idempotency #ifdef.
206    30. I was sent a "project" file called libpcre.a.dev which I understand makes
207        building PCRE on Windows easier, so I have included it in the distribution.
209    31. There is now a check in pcretest against a ridiculously large number being
210        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
211        loop, the loop is abandoned.
213    32. Forward references to subpatterns in conditions such as (?(2)...) where
214        subpattern 2 is defined later cause pcre_compile() to search forwards in
215        the pattern for the relevant set of parentheses. This search went wrong
216        when there were unescaped parentheses in a character class, parentheses
217        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
219    33. "Subroutine" calls and backreferences were previously restricted to
220        referencing subpatterns earlier in the regex. This restriction has now
221        been removed.
223    34. Added a number of extra features that are going to be in Perl 5.10. On the
224        whole, these are just syntactic alternatives for features that PCRE had
225        previously implemented using the Python syntax or my own invention. The
226        other formats are all retained for compatibility.
228        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
229            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
230            also .NET compatible.
232        (b) A recursion or subroutine call to a named group can now be defined as
233            (?&name) as well as (?P>name).
235        (c) A backreference to a named group can now be defined as \k<name> or
236            \k'name' as well as (?P=name). The new forms, as well as being in Perl
237            5.10, are also .NET compatible.
239        (d) A conditional reference to a named group can now use the syntax
240            (?(<name>) or (?('name') as well as (?(name).
242        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
243            groups (named and numbered) that are never evaluated inline, but can be
244            called as "subroutines" from elsewhere. In effect, the DEFINE condition
245            is always false. There may be only one alternative in such a group.
247        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
248            as the simple (?(R). The condition is true only if the most recent
249            recursion is that of the given number or name. It does not search out
250            through the entire recursion stack.
252        (g) The escape \gN or \g{N} has been added, where N is a positive or
253            negative number, specifying an absolute or relative reference.
255    35. Tidied to get rid of some further signed/unsigned compiler warnings and
256        some "unreachable code" warnings.
258    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
259        things, this adds five new scripts.
261    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
262        There were also incompatibilities regarding the handling of \Q..\E inside
263        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
264        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
266    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
267        matches an empty string, and forcibly breaks the loop. There were bugs in
268        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
269        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
270        separate and independent bugs (that affected different cases) have been
271        fixed.
273    39. Refactored the code to abolish the use of different opcodes for small
274        capturing bracket numbers. This is a tidy that I avoided doing when I
275        removed the limit on the number of capturing brackets for 3.5 back in 2001.
276        The new approach is not only tidier, it makes it possible to reduce the
277        memory needed to fix the previous bug (38).
279    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
280        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
281        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
282        mode.
284    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
285        report.
287    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
288        copy construction and assignment in the C++ wrapper.
290    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
291        couple of bugs that could have given wrong results in the "--newline=crlf"
292        case.
294    44. Added a number of casts and did some reorganization of signed/unsigned int
295        variables following suggestions from Dair Grant. Also renamed the variable
296        "this" as "item" because it is a C++ keyword.
298    45. Arranged for dftables to add
300          #include "pcre_internal.h"
302        to pcre_chartables.c because without it, gcc 4.x may remove the array
303        definition from the final binary if PCRE is built into a static library and
304        dead code stripping is activated.
306    46. For an unanchored pattern, if a match attempt fails at the start of a
307        newline sequence, and the newline setting is CRLF or ANY, and the next two
308        characters are CRLF, advance by two characters instead of one.
311    Version 6.7 04-Jul-06
312    ---------------------
314     1. In order to handle tests when input lines are enormously long, pcretest has
315        been re-factored so that it automatically extends its buffers when
316        necessary. The code is crude, but this _is_ just a test program. The
317        default size has been increased from 32K to 50K.
319     2. The code in pcre_study() was using the value of the re argument before
320        testing it for NULL. (Of course, in any sensible call of the function, it
321        won't be NULL.)
323     3. The memmove() emulation function in pcre_internal.h, which is used on
324        systems that lack both memmove() and bcopy() - that is, hardly ever -
325        was missing a "static" storage class specifier.
327     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
328        containing an extended class (one that cannot be represented by a bitmap
329        because it contains high-valued characters or Unicode property items, e.g.
330        [\pZ]). Almost always one would set UTF-8 mode when processing such a
331        pattern, but PCRE should not loop if you do not (it no longer does).
332        [Detail: two cases were found: (a) a repeated subpattern containing an
333        extended class; (b) a recursive reference to a subpattern that followed a
334        previous extended class. It wasn't skipping over the extended class
335        correctly when UTF-8 mode was not set.]
337     5. A negated single-character class was not being recognized as fixed-length
338        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
339        compile error "lookbehind assertion is not fixed length".
341     6. The RunPerlTest auxiliary script was showing an unexpected difference
342        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
343        write a Perl script that can interpret lines of an input file either as
344        byte characters or as UTF-8, which is what "perltest" was being required to
345        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
346        can't do is switch easily at run time between having the "use utf8;" pragma
347        or not. In the end, I fudged it by using the RunPerlTest script to insert
348        "use utf8;" explicitly for the UTF-8 tests.
350     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
351        the end of the subject string, contrary to the documentation and to what
352        Perl does. This was true of both matching functions. Now it matches only at
353        the start of the subject and immediately after *internal* newlines.
355     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
356        a pointer to an int instead of a pointer to an unsigned long int. This
357        caused problems on 64-bit systems.
359     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
360        instance of the 'standard' template library not being so standard".
362    10. There was no check on the number of named subpatterns nor the maximum
363        length of a subpattern name. The product of these values is used to compute
364        the size of the memory block for a compiled pattern. By supplying a very
365        long subpattern name and a large number of named subpatterns, the size
366        computation could be caused to overflow. This is now prevented by limiting
367        the length of names to 32 characters, and the number of named subpatterns
368        to 10,000.
370    11. Subpatterns that are repeated with specific counts have to be replicated in
371        the compiled pattern. The size of memory for this was computed from the
372        length of the subpattern and the repeat count. The latter is limited to
373        65535, but there was no limit on the former, meaning that integer overflow
374        could in principle occur. The compiled length of a repeated subpattern is
375        now limited to 30,000 bytes in order to prevent this.
377    12. Added the optional facility to have named substrings with the same name.
379    13. Added the ability to use a named substring as a condition, using the
380        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
381        are numbers (not recommended). Forward references are permitted.
383    14. Added forward references in named backreferences (if you see what I mean).
385    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
386        pattern could run off the end of the subject. For example, the pattern
387        "(?s)(.{1,5})"8 did this with the subject "ab".
389    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
390        PCRE_CASELESS was set when matching characters that were quantified with ?
391        or *.
393    17. A character class other than a single negated character that had a minimum
394        but no maximum quantifier - for example [ab]{6,} - was not handled
395        correctly by pce_dfa_exec(). It would match only one character.
397    18. A valid (though odd) pattern that looked like a POSIX character
398        class but used an invalid character after [ (for example [[,abc,]]) caused
399        pcre_compile() to give the error "Failed: internal error: code overflow" or
400        in some cases to crash with a glibc free() error. This could even happen if
401        the pattern terminated after [[ but there just happened to be a sequence of
402        letters, a binary zero, and a closing ] in the memory that followed.
404    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
405        over the years. Originally (before any Unicode support), just the bottom 8
406        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
407        output from "man perlunicode" includes this:
409          The regular expression compiler produces polymorphic opcodes.  That
410          is, the pattern adapts to the data and automatically switches to
411          the Unicode character scheme when presented with Unicode data--or
412          instead uses a traditional byte scheme when presented with byte
413          data.
415        Sadly, a wide octal escape does not cause a switch, and in a string with
416        no other multibyte characters, these octal escapes are treated as before.
417        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
418        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
419        Unicode string.
421        I have not perpetrated such confusion in PCRE. Up till now, it took just
422        the bottom 8 bits, as in old Perl. I have now made octal escapes with
423        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
424        translate to the appropriate multibyte character.
426    29. Applied some refactoring to reduce the number of warnings from Microsoft
427        and Borland compilers. This has included removing the fudge introduced
428        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
429        a warning about an unused variable.
431    21. PCRE has not included VT (character 0x0b) in the set of whitespace
432        characters since release 4.0, because Perl (from release 5.004) does not.
433        [Or at least, is documented not to: some releases seem to be in conflict
434        with the documentation.] However, when a pattern was studied with
435        pcre_study() and all its branches started with \s, PCRE still included VT
436        as a possible starting character. Of course, this did no harm; it just
437        caused an unnecessary match attempt.
439    22. Removed a now-redundant internal flag bit that recorded the fact that case
440        dependency changed within the pattern. This was once needed for "required
441        byte" processing, but is no longer used. This recovers a now-scarce options
442        bit. Also moved the least significant internal flag bit to the most-
443        significant bit of the word, which was not previously used (hangover from
444        the days when it was an int rather than a uint) to free up another bit for
445        the future.
447    23. Added support for CRLF line endings as well as CR and LF. As well as the
448        default being selectable at build time, it can now be changed at runtime
449        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
450        specify that it is scanning data with non-default line endings.
452    24. Changed the definition of CXXLINK to make it agree with the definition of
453        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
455    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
456        recursions. This makes a big different to stack usage for some patterns.
458    26. If a subpattern containing a named recursion or subroutine reference such
459        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
460        the space required for the compiled pattern went wrong and gave too small a
461        value. Depending on the environment, this could lead to "Failed: internal
462        error: code overflow at offset 49" or "glibc detected double free or
463        corruption" errors.
465    27. Applied patches from Google (a) to support the new newline modes and (b) to
466        advance over multibyte UTF-8 characters in GlobalReplace.
468    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
469        difference for some implementation of PCRE in some Windows version.
471    29. Added some extra testing facilities to pcretest:
473        \q<number>   in a data line sets the "match limit" value
474        \Q<number>   in a data line sets the "match recursion limt" value
475        -S <number>  sets the stack size, where <number> is in megabytes
477        The -S option isn't available for Windows.
480    Version 6.6 06-Feb-06
481    ---------------------
483     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
484        in pcreposix.h. I have copied the definition from pcre.h.
486     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
487        because pcre.h is no longer a built file.
489     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
490        not normally included in the compiled code.
493    Version 6.5 01-Feb-06
494    ---------------------
496     1. When using the partial match feature with pcre_dfa_exec(), it was not
497        anchoring the second and subsequent partial matches at the new starting
498        point. This could lead to incorrect results. For example, with the pattern
499        /1234/, partially matching against "123" and then "a4" gave a match.
501     2. Changes to pcregrep:
503        (a) All non-match returns from pcre_exec() were being treated as failures
504            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
505            error message is output. Some extra information is given for the
506            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
507            probably the only errors that are likely to be caused by users (by
508            specifying a regex that has nested indefinite repeats, for instance).
509            If there are more than 20 of these errors, pcregrep is abandoned.
511        (b) A binary zero was treated as data while matching, but terminated the
512            output line if it was written out. This has been fixed: binary zeroes
513            are now no different to any other data bytes.
515        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
516            used to set a locale for matching. The --locale=xxxx long option has
517            been added (no short equivalent) to specify a locale explicitly on the
518            pcregrep command, overriding the environment variables.
520        (d) When -B was used with -n, some line numbers in the output were one less
521            than they should have been.
523        (e) Added the -o (--only-matching) option.
525        (f) If -A or -C was used with -c (count only), some lines of context were
526            accidentally printed for the final match.
528        (g) Added the -H (--with-filename) option.
530        (h) The combination of options -rh failed to suppress file names for files
531            that were found from directory arguments.
533        (i) Added the -D (--devices) and -d (--directories) options.
535        (j) Added the -F (--fixed-strings) option.
537        (k) Allow "-" to be used as a file name for -f as well as for a data file.
539        (l) Added the --colo(u)r option.
541        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
542            is not present by default.
544     3. A nasty bug was discovered in the handling of recursive patterns, that is,
545        items such as (?R) or (?1), when the recursion could match a number of
546        alternatives. If it matched one of the alternatives, but subsequently,
547        outside the recursion, there was a failure, the code tried to back up into
548        the recursion. However, because of the way PCRE is implemented, this is not
549        possible, and the result was an incorrect result from the match.
551        In order to prevent this happening, the specification of recursion has
552        been changed so that all such subpatterns are automatically treated as
553        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
555     4. I had overlooked the fact that, in some locales, there are characters for
556        which isalpha() is true but neither isupper() nor islower() are true. In
557        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
558        and ordfeminine) are like this. This affected the treatment of \w and \W
559        when they appeared in character classes, but not when they appeared outside
560        a character class. The bit map for "word" characters is now created
561        separately from the results of isalnum() instead of just taking it from the
562        upper, lower, and digit maps. (Plus the underscore character, of course.)
564     5. The above bug also affected the handling of POSIX character classes such as
565        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
566        permanent tables. Instead, the bit maps for such a class were previously
567        created as the appropriate unions of the upper, lower, and digit bitmaps.
568        Now they are created by subtraction from the [[:word:]] class, which has
569        its own bitmap.
571     6. The [[:blank:]] character class matches horizontal, but not vertical space.
572        It is created by subtracting the vertical space characters (\x09, \x0a,
573        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
574        subtraction was done in the overall bitmap for a character class, meaning
575        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
576        be recognized. This bug has been fixed.
578     7. Patches from the folks at Google:
580          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
581          real life, but is still worth protecting against".
583          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
584          regular expressions".
586          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
587          have it.
589          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
590          "configure" and the latter not, in order to fix a problem somebody had
591          with compiling the Arg class on HP-UX.
593          (e) Improve the error-handling of the C++ wrapper a little bit.
595          (f) New tests for checking recursion limiting.
597     8. The pcre_memmove() function, which is used only if the environment does not
598        have a standard memmove() function (and is therefore rarely compiled),
599        contained two bugs: (a) use of int instead of size_t, and (b) it was not
600        returning a result (though PCRE never actually uses the result).
602     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
603        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
604        returned instead of calling malloc() with an overflowing number that would
605        most likely cause subsequent chaos.
607    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
609    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
610        with this option is matched, the nmatch and pmatch options of regexec() are
611        ignored.
613    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
614        provided in case anyone wants to the the POSIX interface with UTF-8
615        strings.
617    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
618        C++ linking (needed for some HP-UX environments).
620    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
621        (unused parameter) and in the pcre_printint() function (omitted "default"
622        switch label when the default is to do nothing).
624    15. Added some code to make it possible, when PCRE is compiled as a C++
625        library, to replace subject pointers for pcre_exec() with a smart pointer
626        class, thus making it possible to process discontinuous strings.
628    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
629        much the same function. They were added by different people who were trying
630        to make PCRE easy to compile on non-Unix systems. It has been suggested
631        that PCRE_EXPORT be abolished now that there is more automatic apparatus
632        for compiling on Windows systems. I have therefore replaced it with
633        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
634        defaults to "extern" for C or "extern C" for C++, which works fine on
635        Unix-like systems. It is now possible to override the value of PCRE_DATA_
636        SCOPE with something explicit in config.h. In addition:
638        (a) pcreposix.h still had just "extern" instead of either of these macros;
639            I have replaced it with PCRE_DATA_SCOPE.
641        (b) Functions such as _pcre_xclass(), which are internal to the library,
642            but external in the C sense, all had PCRE_EXPORT in their definitions.
643            This is apparently wrong for the Windows case, so I have removed it.
644            (It makes no difference on Unix-like systems.)
646    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
647        of recursive calls to match(). This is different to MATCH_LIMIT because
648        that limits the total number of calls to match(), not all of which increase
649        the depth of recursion. Limiting the recursion depth limits the amount of
650        stack (or heap if NO_RECURSE is set) that is used. The default can be set
651        when PCRE is compiled, and changed at run time. A patch from Google adds
652        this functionality to the C++ interface.
654    18. Changes to the handling of Unicode character properties:
656        (a) Updated the table to Unicode 4.1.0.
658        (b) Recognize characters that are not in the table as "Cn" (undefined).
660        (c) I revised the way the table is implemented to a much improved format
661            which includes recognition of ranges. It now supports the ranges that
662            are defined in UnicodeData.txt, and it also amalgamates other
663            characters into ranges. This has reduced the number of entries in the
664            table from around 16,000 to around 3,000, thus reducing its size
665            considerably. I realized I did not need to use a tree structure after
666            all - a binary chop search is just as efficient. Having reduced the
667            number of entries, I extended their size from 6 bytes to 8 bytes to
668            allow for more data.
670        (d) Added support for Unicode script names via properties such as \p{Han}.
672    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
673        matching that character.
675    20. When matching a repeated Unicode property with a minimum greater than zero,
676        (for example \pL{2,}), PCRE could look past the end of the subject if it
677        reached it while seeking the minimum number of characters. This could
678        happen only if some of the characters were more than one byte long, because
679        there is a check for at least the minimum number of bytes.
681    21. Refactored the implementation of \p and \P so as to be more general, to
682        allow for more different types of property in future. This has changed the
683        compiled form incompatibly. Anybody with saved compiled patterns that use
684        \p or \P will have to recompile them.
686    22. Added "Any" and "L&" to the supported property types.
688    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
689        but give a compile time error if the value is greater than 0xff.
691    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
692        accidentally not being installed or uninstalled.
694    25. The pcre.h file was built from pcre.h.in, but the only changes that were
695        made were to insert the current release number. This seemed silly, because
696        it made things harder for people building PCRE on systems that don't run
697        "configure". I have turned pcre.h into a distributed file, no longer built
698        by "configure", with the version identification directly included. There is
699        no longer a pcre.h.in file.
701        However, this change necessitated a change to the pcre-config script as
702        well. It is built from pcre-config.in, and one of the substitutions was the
703        release number. I have updated configure.ac so that ./configure now finds
704        the release number by grepping pcre.h.
706    26. Added the ability to run the tests under valgrind.
709    Version 6.4 05-Sep-05
710    ---------------------
712     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
713        "--" to be printed when multiple files were scanned, even when none of the
714        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
715        consider it to be a bug, and have restored the previous behaviour.
717     2. A couple of code tidies to get rid of compiler warnings.
719     3. The pcretest program used to cheat by referring to symbols in the library
720        whose names begin with _pcre_. These are internal symbols that are not
721        really supposed to be visible externally, and in some environments it is
722        possible to suppress them. The cheating is now confined to including
723        certain files from the library's source, which is a bit cleaner.
725     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
726        file's purpose clearer.
728     5. Reorganized pcre_ucp_findchar().
731    Version 6.3 15-Aug-05
732    ---------------------
734     1. The file libpcre.pc.in did not have general read permission in the tarball.
736     2. There were some problems when building without C++ support:
738        (a) If C++ support was not built, "make install" and "make test" still
739            tried to test it.
741        (b) There were problems when the value of CXX was explicitly set. Some
742            changes have been made to try to fix these, and ...
744        (c) --disable-cpp can now be used to explicitly disable C++ support.
746        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
747            backslash in a target when C++ was disabled. This confuses some
748            versions of "make", apparently. Using an intermediate variable solves
749            this. (Same for CPP_LOBJ.)
751     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
752        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
753        necessary on certain architectures.
755     4. Added a setting of -export-symbols-regex to the link command to remove
756        those symbols that are exported in the C sense, but actually are local
757        within the library, and not documented. Their names all begin with
758        "_pcre_". This is not a perfect job, because (a) we have to except some
759        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
760        available (and never for static libraries). I have made a note to try to
761        find a way round (a) in the future.
764    Version 6.2 01-Aug-05
765    ---------------------
767     1. There was no test for integer overflow of quantifier values. A construction
768        such as {1111111111111111} would give undefined results. What is worse, if
769        a minimum quantifier for a parenthesized subpattern overflowed and became
770        negative, the calculation of the memory size went wrong. This could have
771        led to memory overwriting.
773     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
775     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
776        operating environments where this matters.
778     4. Applied Giuseppe Maxia's patch to add additional features for controlling
779        PCRE options from within the C++ wrapper.
781     5. Named capturing subpatterns were not being correctly counted when a pattern
782        was compiled. This caused two problems: (a) If there were more than 100
783        such subpatterns, the calculation of the memory needed for the whole
784        compiled pattern went wrong, leading to an overflow error. (b) Numerical
785        back references of the form \12, where the number was greater than 9, were
786        not recognized as back references, even though there were sufficient
787        previous subpatterns.
789     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
790        versions of gcc, e.g. 2.95.4.
793    Version 6.1 21-Jun-05
794    ---------------------
796     1. There was one reference to the variable "posix" in pcretest.c that was not
797        surrounded by "#if !defined NOPOSIX".
799     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
800        the cross-check on the old pcre_info() function, for the benefit of the
801        cut-down version of PCRE that is currently imported into Exim.
803     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
804        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
805        patterns that start (?i) but I don't think that matters. The use of (?i) is
806        just an example; this all applies to the other options as well.
808     4. Since libtool seems to echo the compile commands it is issuing, the output
809        from "make" can be reduced a bit by putting "@" in front of each libtool
810        compile command.
812     5. Patch from the folks at Google for configure.in to be a bit more thorough
813        in checking for a suitable C++ installation before trying to compile the
814        C++ stuff. This should fix a reported problem when a compiler was present,
815        but no suitable headers.
817     6. The man pages all had just "PCRE" as their title. I have changed them to
818        be the relevant file name. I have also arranged that these names are
819        retained in the file doc/pcre.txt, which is a concatenation in text format
820        of all the man pages except the little individual ones for each function.
822     7. The NON-UNIX-USE file had not been updated for the different set of source
823        files that come with release 6. I also added a few comments about the C++
824        wrapper.
827    Version 6.0 07-Jun-05
828    ---------------------
830     1. Some minor internal re-organization to help with my DFA experiments.
832     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
833        didn't matter for the library itself when fully configured, but did matter
834        when compiling without UCP support, or within Exim, where the ucp files are
835        not imported.
837     3. Refactoring of the library code to split up the various functions into
838        different source modules. The addition of the new DFA matching code (see
839        below) to a single monolithic source would have made it really too
840        unwieldy, quite apart from causing all the code to be include in a
841        statically linked application, when only some functions are used. This is
842        relevant even without the DFA addition now that patterns can be compiled in
843        one application and matched in another.
845        The downside of splitting up is that there have to be some external
846        functions and data tables that are used internally in different modules of
847        the library but which are not part of the API. These have all had their
848        names changed to start with "_pcre_" so that they are unlikely to clash
849        with other external names.
851     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
852        a different (DFA) algorithm. Although it is slower than the original
853        function, it does have some advantages for certain types of matching
854        problem.
856     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
857        including restarting after a partial match.
859     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
860        defined when compiling for Windows was sent to me. I have put it into the
861        code, though I have no means of testing or verifying it.
863     7. Added the pcre_refcount() auxiliary function.
865     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
866        match before or at the first newline in the subject string. In pcretest,
867        the /f option on a pattern can be used to set this.
869     9. A repeated \w when used in UTF-8 mode with characters greater than 256
870        would behave wrongly. This has been present in PCRE since release 4.0.
872    10. A number of changes to the pcregrep command:
874        (a) Refactored how -x works; insert ^(...)$ instead of setting
875            PCRE_ANCHORED and checking the length, in preparation for adding
876            something similar for -w.
878        (b) Added the -w (match as a word) option.
880        (c) Refactored the way lines are read and buffered so as to have more
881            than one at a time available.
883        (d) Implemented a pcregrep test script.
885        (e) Added the -M (multiline match) option. This allows patterns to match
886            over several lines of the subject. The buffering ensures that at least
887            8K, or the rest of the document (whichever is the shorter) is available
888            for matching (and similarly the previous 8K for lookbehind assertions).
890        (f) Changed the --help output so that it now says
892              -w, --word-regex(p)
894            instead of two lines, one with "regex" and the other with "regexp"
895            because that confused at least one person since the short forms are the
896            same. (This required a bit of code, as the output is generated
897            automatically from a table. It wasn't just a text change.)
899        (g) -- can be used to terminate pcregrep options if the next thing isn't an
900            option but starts with a hyphen. Could be a pattern or a path name
901            starting with a hyphen, for instance.
903        (h) "-" can be given as a file name to represent stdin.
905        (i) When file names are being printed, "(standard input)" is used for
906            the standard input, for compatibility with GNU grep. Previously
907            "<stdin>" was used.
909        (j) The option --label=xxx can be used to supply a name to be used for
910            stdin when file names are being printed. There is no short form.
912        (k) Re-factored the options decoding logic because we are going to add
913            two more options that take data. Such options can now be given in four
914            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
916        (l) Added the -A, -B, and -C options for requesting that lines of context
917            around matches be printed.
919        (m) Added the -L option to print the names of files that do not contain
920            any matching lines, that is, the complement of -l.
922        (n) The return code is 2 if any file cannot be opened, but pcregrep does
923            continue to scan other files.
925        (o) The -s option was incorrectly implemented. For compatibility with other
926            greps, it now suppresses the error message for a non-existent or non-
927            accessible file (but not the return code). There is a new option called
928            -q that suppresses the output of matching lines, which was what -s was
929            previously doing.
931        (p) Added --include and --exclude options to specify files for inclusion
932            and exclusion when recursing.
934    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
935        Hopefully, it now does.
937    12. Missing cast in pcre_study().
939    13. Added an "uninstall" target to the makefile.
941    14. Replaced "extern" in the function prototypes in Makefile.in with
942        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
943        world, but is set differently for Windows.
945    15. Added a second compiling function called pcre_compile2(). The only
946        difference is that it has an extra argument, which is a pointer to an
947        integer error code. When there is a compile-time failure, this is set
948        non-zero, in addition to the error test pointer being set to point to an
949        error message. The new argument may be NULL if no error number is required
950        (but then you may as well call pcre_compile(), which is now just a
951        wrapper). This facility is provided because some applications need a
952        numeric error indication, but it has also enabled me to tidy up the way
953        compile-time errors are handled in the POSIX wrapper.
955    16. Added VPATH=.libs to the makefile; this should help when building with one
956        prefix path and installing with another. (Or so I'm told by someone who
957        knows more about this stuff than I do.)
959    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
960        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
961        match everything, including newlines. This is not POSIX-compatible, but
962        somebody wanted the feature. From pcretest it can be activated by using
963        both the P and the s flags.
965    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
967    19. libpcre.pc was being incorrectly installed as executable.
969    20. A couple of places in pcretest check for end-of-line by looking for '\n';
970        it now also looks for '\r' so that it will work unmodified on Windows.
972    21. Added Google's contributed C++ wrapper to the distribution.
974    22. Added some untidy missing memory free() calls in pcretest, to keep
975        Electric Fence happy when testing.
979    Version 5.0 13-Sep-04
980    ---------------------
982     1. Internal change: literal characters are no longer packed up into items
983        containing multiple characters in a single byte-string. Each character
984        is now matched using a separate opcode. However, there may be more than one
985        byte in the character in UTF-8 mode.
987     2. The pcre_callout_block structure has two new fields: pattern_position and
988        next_item_length. These contain the offset in the pattern to the next match
989        item, and its length, respectively.
991     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
992        insertion of callouts before each pattern item. Added the /C option to
993        pcretest to make use of this.
995     4. On the advice of a Windows user, the lines
997          #if defined(_WIN32) || defined(WIN32)
998          _setmode( _fileno( stdout ), 0x8000 );
999          #endif  /* defined(_WIN32) || defined(WIN32) */
1001        have been added to the source of pcretest. This apparently does useful
1002        magic in relation to line terminators.
1004     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1005        for the benefit of those environments where the "b" makes a difference.
1007     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1008        to know about it. I have put a hack into configure.in that adds in code
1009        to set GCC=yes if CC=icc. This seems to end up at a point in the
1010        generated configure script that is early enough to affect the setting of
1011        compiler options, which is what is needed, but I have no means of testing
1012        whether it really works. (The user who reported this had patched the
1013        generated configure script, which of course I cannot do.)
1015        LATER: After change 22 below (new libtool files), the configure script
1016        seems to know about icc (and also ecc). Therefore, I have commented out
1017        this hack in configure.in.
1019     7. Added support for pkg-config (2 patches were sent in).
1021     8. Negated POSIX character classes that used a combination of internal tables
1022        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1023        [[:^ascii]]. Typically, they would match almost any characters. The other
1024        POSIX classes were not broken in this way.
1026     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1027        to find the match, as PCRE was deluded into thinking that the match had to
1028        start at the start point or following a newline. The same bug applied to
1029        patterns with negative forward assertions or any backward assertions
1030        preceding ".*" at the start, unless the pattern required a fixed first
1031        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1033    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1034        starting at the last subject character, bytes beyond the end of the subject
1035        string were read.
1037    11. Renamed the variable "class" as "classbits" to make life easier for C++
1038        users. (Previously there was a macro definition, but it apparently wasn't
1039        enough.)
1041    12. Added the new field "tables" to the extra data so that tables can be passed
1042        in at exec time, or the internal tables can be re-selected. This allows
1043        a compiled regex to be saved and re-used at a later time by a different
1044        program that might have everything at different addresses.
1046    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1047        -R library as well as a -L library.
1049    14. The debugging options of pcretest (-d on the command line or D on a
1050        pattern) showed incorrect output for anything following an extended class
1051        that contained multibyte characters and which was followed by a quantifier.
1053    15. Added optional support for general category Unicode character properties
1054        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1055        support. It adds about 90K to the size of the library. The meanings of the
1056        inbuilt class escapes such as \d and \s have NOT been changed.
1058    16. Updated pcredemo.c to include calls to free() to release the memory for the
1059        compiled pattern.
1061    17. The generated file chartables.c was being created in the source directory
1062        instead of in the building directory. This caused the build to fail if the
1063        source directory was different from the building directory, and was
1064        read-only.
1066    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1067        file. No doubt somebody will tell me if they don't make sense... Also added
1068        Dan Mooney's comments about building on OpenVMS.
1070    19. Added support for partial matching via the PCRE_PARTIAL option for
1071        pcre_exec() and the \P data escape in pcretest.
1073    20. Extended pcretest with 3 new pattern features:
1075        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1076              write the compiled pattern to the file whose name is "rest-of-line".
1077              This is a straight binary dump of the data, with the saved pointer to
1078              the character tables forced to be NULL. The study data, if any, is
1079              written too. After writing, pcretest reads a new pattern.
1081        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1082              compiled pattern from the given file. There must not be any
1083              occurrences of "<" in the file name (pretty unlikely); if there are,
1084              pcretest will instead treat the initial "<" as a pattern delimiter.
1085              After reading in the pattern, pcretest goes on to read data lines as
1086              usual.
1088        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1089              and 16-bit fields in a compiled pattern, to simulate a pattern that
1090              was compiled on a host of opposite endianness.
1092    21. The pcre-exec() function can now cope with patterns that were compiled on
1093        hosts of opposite endianness, with this restriction:
1095          As for any compiled expression that is saved and used later, the tables
1096          pointer field cannot be preserved; the extra_data field in the arguments
1097          to pcre_exec() should be used to pass in a tables address if a value
1098          other than the default internal tables were used at compile time.
1100    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1101        now diagnosed as an error. Previously, most of the time, a negative number
1102        would have been treated as zero, but if in addition "ovector" was passed as
1103        NULL, a crash could occur.
1105    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1106        new versions from the libtool 1.5 distribution (the last one is a copy of
1107        a file called libtool.m4). This seems to have fixed the need to patch
1108        "configure" to support Darwin 1.3 (which I used to do). However, I still
1109        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1110        workstation).
1112    24. Changed the PCRE licence to be the more standard "BSD" licence.
1115    Version 4.5 01-Dec-03
1116    ---------------------
1118     1. There has been some re-arrangement of the code for the match() function so
1119        that it can be compiled in a version that does not call itself recursively.
1120        Instead, it keeps those local variables that need separate instances for
1121        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1122        needs to "recurse". Keeping track of where control must go is done by means
1123        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1124        hide most of the details from the main code, and operates only if
1125        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1126        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1127        operating.
1129        To make it easier for callers to provide specially tailored get/free
1130        functions for this usage, two new functions, pcre_stack_malloc, and
1131        pcre_stack_free, are used. They are always called in strict stacking order,
1132        and the size of block requested is always the same.
1134        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1135        PCRE has been compiled to use the stack or the heap for recursion. The
1136        -C option of pcretest uses this to show which version is compiled.
1138        A new data escape \S, is added to pcretest; it causes the amounts of store
1139        obtained and freed by both kinds of malloc/free at match time to be added
1140        to the output.
1142     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1143        what's available on my current Linux desktop machine.
1145     3. When matching a UTF-8 string, the test for a valid string at the start has
1146        been extended. If start_offset is not zero, PCRE now checks that it points
1147        to a byte that is the start of a UTF-8 character. If not, it returns
1148        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1149        this is necessary because there may be backward assertions in the pattern.
1150        When matching the same subject several times, it may save resources to use
1151        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1153     4. The code for checking the validity of UTF-8 strings has been tightened so
1154        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1155        containing "overlong sequences".
1157     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1158        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1159        should have been "&", but it just so happened that all the cases this let
1160        through by mistake were picked up later in the function.
1162     6. I had used a variable called "isblank" - this is a C99 function, causing
1163        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1165     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1166        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1167        so the version is shown; (c) stop "make test" echoing "./RunTest".
1169     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1171     9. The prototype for memmove() for systems that don't have it was using
1172        size_t, but the inclusion of the header that defines size_t was later. I've
1173        moved the #includes for the C headers earlier to avoid this.
1175    10. Added some adjustments to the code to make it easier to compiler on certain
1176        special systems:
1178          (a) Some "const" qualifiers were missing.
1179          (b) Added the macro EXPORT before all exported functions; by default this
1180              is defined to be empty.
1181          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1182              that it reads its output file name as an argument instead of writing
1183              to the standard output and assuming this can be redirected.
1185    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1186        class containing characters with values greater than 255, PCRE compilation
1187        went into a loop.
1189    12. A recursive reference to a subpattern that was within another subpattern
1190        that had a minimum quantifier of zero caused PCRE to crash. For example,
1191        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1192        recursion. If the recursively-called subpattern itself had a zero repeat,
1193        that was OK.
1195    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1196        buffer into which it was copied (for escape processing) was still set at
1197        1024, so long lines caused crashes.
1199    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1200        "internal error: code overflow...". This applied to any character class
1201        that was followed by a possessive quantifier.
1203    15. Modified the Makefile to add libpcre.la as a prerequisite for
1204        libpcreposix.la because I was told this is needed for a parallel build to
1205        work.
1207    16. If a pattern that contained .* following optional items at the start was
1208        studied, the wrong optimizing data was generated, leading to matching
1209        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1210        matching string must start with a or b or c. The correct conclusion for
1211        this pattern is that a match can start with any character.
1214    Version 4.4 13-Aug-03
1215    ---------------------
1217     1. In UTF-8 mode, a character class containing characters with values between
1218        127 and 255 was not handled correctly if the compiled pattern was studied.
1219        In fixing this, I have also improved the studying algorithm for such
1220        classes (slightly).
1222     2. Three internal functions had redundant arguments passed to them. Removal
1223        might give a very teeny performance improvement.
1225     3. Documentation bug: the value of the capture_top field in a callout is *one
1226        more than* the number of the hightest numbered captured substring.
1228     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1229        in incorrectly linking with a previously installed version. They now link
1230        explicitly with libpcre.la.
1232     5. configure.in no longer needs to recognize Cygwin specially.
1234     6. A problem in pcre.in for Windows platforms is fixed.
1236     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1237        pcretest, it used to include the size of the study block as part of its
1238        output. Unfortunately, the structure contains a field that has a different
1239        size on different hardware architectures. This meant that the tests that
1240        showed this size failed. As the block is currently always of a fixed size,
1241        this information isn't actually particularly useful in pcretest output, so
1242        I have just removed it.
1244     8. Three pre-processor statements accidentally did not start in column 1.
1245        Sadly, there are *still* compilers around that complain, even though
1246        standard C has not required this for well over a decade. Sigh.
1248     9. In pcretest, the code for checking callouts passed small integers in the
1249        callout_data field, which is a void * field. However, some picky compilers
1250        complained about the casts involved for this on 64-bit systems. Now
1251        pcretest passes the address of the small integer instead, which should get
1252        rid of the warnings.
1254    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1255        both compile and run time, and gives an error if an invalid UTF-8 sequence
1256        is found. There is a option for disabling this check in cases where the
1257        string is known to be correct and/or the maximum performance is wanted.
1259    11. In response to a bug report, I changed one line in Makefile.in from
1261            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1262        to
1263            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1265        to look similar to other lines, but I have no way of telling whether this
1266        is the right thing to do, as I do not use Windows. No doubt I'll get told
1267        if it's wrong...
1270    Version 4.3 21-May-03
1271    ---------------------
1273    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1274       Makefile.
1276    2. Some refactoring to improve the quality of the code:
1278       (i)   The utf8_table... variables are now declared "const".
1280       (ii)  The code for \cx, which used the "case flipping" table to upper case
1281             lower case letters, now just substracts 32. This is ASCII-specific,
1282             but the whole concept of \cx is ASCII-specific, so it seems
1283             reasonable.
1285       (iii) PCRE was using its character types table to recognize decimal and
1286             hexadecimal digits in the pattern. This is silly, because it handles
1287             only 0-9, a-f, and A-F, but the character types table is locale-
1288             specific, which means strange things might happen. A private
1289             table is now used for this - though it costs 256 bytes, a table is
1290             much faster than multiple explicit tests. Of course, the standard
1291             character types table is still used for matching digits in subject
1292             strings against \d.
1294       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1295             ending in _t are). So I've renamed it as ESC_tee.
1297    3. The first argument for regexec() in the POSIX wrapper should have been
1298       defined as "const".
1300    4. Changed pcretest to use malloc() for its buffers so that they can be
1301       Electric Fenced for debugging.
1303    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1304       to read one or more bytes before the start of the subject string. Often this
1305       had no effect on PCRE's behaviour, but in some circumstances it could
1306       provoke a segmentation fault.
1308    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1309       to try to read one or more bytes before the start of the subject string.
1311    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1312       UTF-8 support could misbehave in various ways if the subject string
1313       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1314       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1315       back over UTF-8 characters.)
1318    Version 4.2 14-Apr-03
1319    ---------------------
1321    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1323    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1324         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1325         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1326         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1327         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1328           and BUILD_EXEEXT
1329         Note: automatic setting of the BUILD variables is not yet working
1330         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1331           compile-time but not at link-time
1332         [LINK]: use for linking executables only
1333         make different versions for Windows and non-Windows
1334         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1335           libraries
1336         [LINK_FOR_BUILD]: new variable
1337         [OBJEXT]: use throughout
1338         [EXEEXT]: use throughout
1339         <winshared>: new target
1340         <wininstall>: new target
1341         <dftables.o>: use native compiler
1342         <dftables>: use native linker
1343         <install>: handle Windows platform correctly
1344         <clean>: ditto
1345         <check>: ditto
1346         copy DLL to top builddir before testing
1348       As part of these changes, -no-undefined was removed again. This was reported
1349       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1350       in any case.
1352    3. Some tidies to get rid of compiler warnings:
1354       . In the match_data structure, match_limit was an unsigned long int, whereas
1355         match_call_count was an int. I've made them both unsigned long ints.
1357       . In pcretest the fact that a const uschar * doesn't automatically cast to
1358         a void * provoked a warning.
1360       . Turning on some more compiler warnings threw up some "shadow" variables
1361         and a few more missing casts.
1363    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1364       option, a class that contained a single character with a value between 128
1365       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1367    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1368       option, a class that contained several characters, but with at least one
1369       whose value was between 128 and 255 caused PCRE to crash.
1372    Version 4.1 12-Mar-03
1373    ---------------------
1375    1. Compiling with gcc -pedantic found a couple of places where casts were
1376    needed, and a string in dftables.c that was longer than standard compilers are
1377    required to support.
1379    2. Compiling with Sun's compiler found a few more places where the code could
1380    be tidied up in order to avoid warnings.
1382    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1383    first of these names is deprecated in the latest Autoconf in favour of the name
1384    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1385    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1386    analogy I have changed it to CFLAGS_FOR_BUILD.
1388    4. Added -no-undefined to the linking command in the Makefile, because this is
1389    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1390    linking step for the pcreposix library.
1392    5. PCRE was failing to diagnose the case of two named groups with the same
1393    name.
1395    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1396    literal character that is needed in the subject for a match, and scans along to
1397    ensure that it is present before embarking on the full matching process. This
1398    saves time in cases of nested unlimited repeats that are never going to match.
1399    Problem: the scan can take a lot of time if the subject is very long (e.g.
1400    megabytes), thus penalizing straightforward matches. It is now done only if the
1401    amount of subject to be scanned is less than 1000 bytes.
1403    7. A lesser problem with the same optimization is that it was recording the
1404    first character of an anchored pattern as "needed", thus provoking a search
1405    right along the subject, even when the first match of the pattern was going to
1406    fail. The "needed" character is now not set for anchored patterns, unless it
1407    follows something in the pattern that is of non-fixed length. Thus, it still
1408    fulfils its original purpose of finding quick non-matches in cases of nested
1409    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1412    Version 4.0 17-Feb-03
1413    ---------------------
1415    1. If a comment in an extended regex that started immediately after a meta-item
1416    extended to the end of string, PCRE compiled incorrect data. This could lead to
1417    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1419    2. Moved to autoconf 2.53 and libtool 1.4.2.
1421    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1422    the special perltest8 script is no longer needed - all the tests can be run
1423    from a single perltest script.
1425    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1426    by \s. It has now been removed in PCRE. This means it isn't recognized as
1427    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1428    class [:space:] *does* include VT, thereby creating a mess.
1430    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1431    space and tab.
1433    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1434    its new features into the main test script, reducing the number of scripts.
1436    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1437    were backward compatible, and made the (?i) apply to the whole pattern, as if
1438    /i were given. Now it behaves more logically, and applies the option setting
1439    only to what follows. PCRE has been changed to follow suit. However, if it
1440    finds options settings right at the start of the pattern, it extracts them into
1441    the global options, as before. Thus, they show up in the info data.
1443    8. Added support for the \Q...\E escape sequence. Characters in between are
1444    treated as literals. This is slightly different from Perl in that $ and @ are
1445    also handled as literals inside the quotes. In Perl, they will cause variable
1446    interpolation. Note the following examples:
1448        Pattern            PCRE matches      Perl matches
1450        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1451        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1452        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1454    For compatibility with Perl, \Q...\E sequences are recognized inside character
1455    classes as well as outside them.
1457    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1458    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1459    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1460    signed/unsigned warnings.
1462    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1463    option for pcretest, so I've replaced it by a simple function that does just
1464    that job.
1466    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1467    "pcregrep -".
1469    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1470    Java package. This provides some syntactic sugar for simple cases of what my
1471    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1472    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1473    item, you can use this simplified notation. Note that only makes sense with
1474    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1475    greediness, whatever the setting of the PCRE_UNGREEDY option.
1477    13. A change of greediness default within a pattern was not taking effect at
1478    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1479    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1480    was abstracted outside.
1482    14. PCRE now supports the \G assertion. It is true when the current matching
1483    position is at the start point of the match. This differs from \A when the
1484    starting offset is non-zero. Used with the /g option of pcretest (or similar
1485    code), it works in the same way as it does for Perl's /g option. If all
1486    alternatives of a regex begin with \G, the expression is anchored to the start
1487    match position, and the "anchored" flag is set in the compiled expression.
1489    15. Some bugs concerning the handling of certain option changes within patterns
1490    have been fixed. These applied to options other than (?ims). For example,
1491    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1492    been the other way round. Some of this was related to change 7 above.
1494    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1495    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1496    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1497    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1499    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1500    mode. Unlike ".", it always matches newline, whatever the setting of
1501    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1502    assertions. Perl allows it, but it doesn't (in general) work because it can't
1503    calculate the length of the lookbehind. At least, that's the case for Perl
1504    5.8.0 - I've been told they are going to document that it doesn't work in
1505    future.
1507    18. Added an error diagnosis for escapes that PCRE does not support: these are
1508    \L, \l, \N, \P, \p, \U, \u, and \X.
1510    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1511    reading past the end of the pattern in cases such as /[abcd/.
1513    20. PCRE was getting more memory than necessary for patterns with classes that
1514    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1516    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1517    compiling PCRE for use with Virtual Pascal.
1519    22. Small fix to the Makefile to make it work properly if the build is done
1520    outside the source tree.
1522    23. Added a new extension: a condition to go with recursion. If a conditional
1523    subpattern starts with (?(R) the "true" branch is used if recursion has
1524    happened, whereas the "false" branch is used only at the top level.
1526    24. When there was a very long string of literal characters (over 255 bytes
1527    without UTF support, over 250 bytes with UTF support), the computation of how
1528    much memory was required could be incorrect, leading to segfaults or other
1529    strange effects.
1531    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1532    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1533    there was a subsequent back reference to those brackets. This meant that, for
1534    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1535    possible to check for precisely this case. All we can do is abandon the
1536    optimization if .* occurs inside capturing brackets when there are any back
1537    references whatsoever. (See below for a better fix that came later.)
1539    26. The handling of the optimization for finding the first character of a
1540    non-anchored pattern, and for finding a character that is required later in the
1541    match were failing in some cases. This didn't break the matching; it just
1542    failed to optimize when it could. The way this is done has been re-implemented.
1544    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1546    28. Added a new feature that provides some of the functionality that Perl
1547    provides with (?{...}). The facility is termed a "callout". The way it is done
1548    in PCRE is for the caller to provide an optional function, by setting
1549    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1550    global variable. By default it is unset, which disables all calling out. To get
1551    the function called, the regex must include (?C) at appropriate points. This
1552    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1553    This provides a means of identifying different callout points. When PCRE
1554    reaches such a point in the regex, if pcre_callout has been set, the external
1555    function is called. It is provided with data in a structure called
1556    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1557    matching continues; if it returns a non-zero value, the match at the current
1558    point fails. However, backtracking will occur if possible. [This was changed
1559    later and other features added - see item 49 below.]
1561    29. pcretest is upgraded to test the callout functionality. It provides a
1562    callout function that displays information. By default, it shows the start of
1563    the match and the current position in the text. There are some new data escapes
1564    to vary what happens:
1566        \C+         in addition, show current contents of captured substrings
1567        \C-         do not supply a callout function
1568        \C!n        return 1 when callout number n is reached
1569        \C!n!m      return 1 when callout number n is reached for the mth time
1571    30. If pcregrep was called with the -l option and just a single file name, it
1572    output "<stdin>" if a match was found, instead of the file name.
1574    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1575    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1576    pcre_exec(). This saves a malloc/free per call. The default value of
1577    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1578    when configuring.
1580    32. The default maximum size of a compiled pattern is 64K. There have been a
1581    few cases of people hitting this limit. The code now uses macros to handle the
1582    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1583    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1584    configuring. Tests 2 and 5 work only with 2-byte links because they output
1585    debugging information about compiled patterns.
1587    33. Internal code re-arrangements:
1589    (a) Moved the debugging function for printing out a compiled regex into
1590        its own source file (printint.c) and used #include to pull it into
1591        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1592        separate copies.
1594    (b) Defined the list of op-code names for debugging as a macro in
1595        internal.h so that it is next to the definition of the opcodes.
1597    (c) Defined a table of op-code lengths for simpler skipping along compiled
1598        code. This is again a macro in internal.h so that it is next to the
1599        definition of the opcodes.
1601    34. Added support for recursive calls to individual subpatterns, along the
1602    lines of Robin Houston's patch (but implemented somewhat differently).
1604    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1605    allow it to read and process whole directories in Win32. This code was
1606    contributed by Lionel Fourquaux; it has not been tested by me.
1608    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1609    used to name a group. Names consist of alphanumerics and underscores, and must
1610    be unique. Back references use the syntax (?P=name) and recursive calls use
1611    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1612    numbers. The function pcre_fullinfo() can be used after compilation to extract
1613    a name/number map. There are three relevant calls:
1615      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1616      PCRE_INFO_NAMECOUNT            yields the number of entries
1617      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1619    The map is a vector of fixed-size entries. The size of each entry depends on
1620    the length of the longest name used. The first two bytes of each entry are the
1621    group number, most significant byte first. There follows the corresponding
1622    name, zero terminated. The names are in alphabetical order.
1624    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1625    case instead of 255. Making it the same both with and without UTF-8 support
1626    means that the same test output works with both.
1628    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1629    calling malloc() with a zero argument.
1631    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1632    optimization. I've improved things by keeping a bitmap of backreferences with
1633    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1634    fact referenced, the optimization can be applied. It is unlikely that a
1635    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1636    the match to follow \n) will appear inside brackets with a number greater than
1637    31, but if it does, any back reference > 31 suppresses the optimization.
1639    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1640    of disabling numbered capturing parentheses. Any opening parenthesis that is
1641    not followed by ? behaves as if it were followed by ?: but named parentheses
1642    can still be used for capturing (and they will acquire numbers in the usual
1643    way).
1645    41. Redesigned the return codes from the match() function into yes/no/error so
1646    that errors can be passed back from deep inside the nested calls. A malloc
1647    failure while inside a recursive subpattern call now causes the
1648    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1650    42. It is now possible to set a limit on the number of times the match()
1651    function is called in a call to pcre_exec(). This facility makes it possible to
1652    limit the amount of recursion and backtracking, though not in a directly
1653    obvious way, because the match() function is used in a number of different
1654    circumstances. The count starts from zero for each position in the subject
1655    string (for non-anchored patterns). The default limit is, for compatibility, a
1656    large number, namely 10 000 000. You can change this in two ways:
1658    (a) When configuring PCRE before making, you can use --with-match-limit=n
1659        to set a default value for the compiled library.
1661    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1662        a different value is set. See 45 below.
1664    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1666    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1667    of things that can be changed at compile time. The first argument specifies
1668    what is wanted and the second points to where the information is to be placed.
1669    The current list of available information is:
1671      PCRE_CONFIG_UTF8
1673    The output is an integer that is set to one if UTF-8 support is available;
1674    otherwise it is set to zero.
1678    The output is an integer that it set to the value of the code that is used for
1679    newline. It is either LF (10) or CR (13).
1683    The output is an integer that contains the number of bytes used for internal
1684    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1688    The output is an integer that contains the threshold above which the POSIX
1689    interface uses malloc() for output vectors. See item 31 above.
1693    The output is an unsigned integer that contains the default limit of the number
1694    of match() calls in a pcre_exec() execution. See 42 above.
1696    44. pcretest has been upgraded by the addition of the -C option. This causes it
1697    to extract all the available output from the new pcre_config() function, and to
1698    output it. The program then exits immediately.
1700    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1701    order to support additional features. One way would have been to define
1702    pcre_exec2() (for example) with extra arguments, but this would not have been
1703    extensible, and would also have required all calls to the original function to
1704    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1705    is used for passing in "extra" data from pcre_study().
1707    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1708    contains the following fields:
1710      flags         a bitmap indicating which of the following fields are set
1711      study_data    opaque data from pcre_study()
1712      match_limit   a way of specifying a limit on match() calls for a specific
1713                      call to pcre_exec()
1714      callout_data  data for callouts (see 49 below)
1716    The flag bits are also defined in pcre.h, and are
1722    The pcre_study() function now returns one of these new pcre_extra blocks, with
1723    the actual study data pointed to by the study_data field, and the
1724    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1725    before. That is, this change is entirely upwards-compatible and requires no
1726    change to existing code.
1728    If you want to pass in additional data to pcre_exec(), you can either place it
1729    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1730    block.
1732    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1733    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1734    times with different match limits, until it finds the minimum value needed for
1735    pcre_exec() to complete. The value is then output. This can be instructive; for
1736    most simple matches the number is quite small, but for pathological cases it
1737    gets very large very quickly.
1739    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1740    returns the size of the data block pointed to by the study_data field in a
1741    pcre_extra block, that is, the value that was passed as the argument to
1742    pcre_malloc() when PCRE was getting memory in which to place the information
1743    created by pcre_study(). The fourth argument should point to a size_t variable.
1744    pcretest has been extended so that this information is shown after a successful
1745    pcre_study() call when information about the compiled regex is being displayed.
1747    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1748    because what follows is always an absolute path. (Later: it turns out that this
1749    is more than cosmetic for MinGW, because it doesn't like empty path
1750    components.)
1752    49. Some changes have been made to the callout feature (see 28 above):
1754    (i)  A callout function now has three choices for what it returns:
1756           0  =>  success, carry on matching
1757         > 0  =>  failure at this point, but backtrack if possible
1758         < 0  =>  serious error, return this value from pcre_exec()
1760         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1761         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1762         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1763         use by callout functions. It will never be used by PCRE itself.
1765    (ii) The pcre_extra structure (see 45 above) has a void * field called
1766         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1767         pcre_callout_block structure has a field of the same name. The contents of
1768         the field passed in the pcre_extra structure are passed to the callout
1769         function in the corresponding field in the callout block. This makes it
1770         easier to use the same callout-containing regex from multiple threads. For
1771         testing, the pcretest program has a new data escape
1773           \C*n        pass the number n (may be negative) as callout_data
1775         If the callout function in pcretest receives a non-zero value as
1776         callout_data, it returns that value.
1778    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1779    there were some redundant $(CFLAGS) in commands that are now specified as
1780    $(LINK), which already includes $(CFLAGS).
1782    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1783    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1784    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1785    one-byte characters throughout. Note that case-insensitive matching applies
1786    only to characters whose values are less than 256. PCRE doesn't support the
1787    notion of cases for higher-valued characters.
1789    (i)   A character class whose characters are all within 0-255 is handled as
1790          a bit map, and the map is inverted for negative classes. Previously, a
1791          character > 255 always failed to match such a class; however it should
1792          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1794    (ii)  A negated character class with a single character < 255 is coded as
1795          "not this character" (OP_NOT). This wasn't working properly when the test
1796          character was multibyte, either singly or repeated.
1798    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1799          mode, for example: \x{100}{2,3}.
1801    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1802          singly or repeated) now correctly test multibyte characters. However,
1803          PCRE doesn't recognize any characters with values greater than 255 as
1804          digits, spaces, or word characters. Such characters always match \D, \S,
1805          and \W, and never match \d, \s, or \w.
1807    (v)   Classes may now contain characters and character ranges with values
1808          greater than 255. For example: [ab\x{100}-\x{400}].
1810    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1811          PCRE in UTF-8 mode.
1813    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1814    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1815    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1816    value.)
1818    53. The single man page has become too large. I have therefore split it up into
1819    a number of separate man pages. These also give rise to individual HTML pages;
1820    these are now put in a separate directory, and there is an index.html page that
1821    lists them all. Some hyperlinking between the pages has been installed.
1823    54. Added convenience functions for handling named capturing parentheses.
1825    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1826    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1827    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1828    are faulted.
1830    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1831    calling configure. These values are used when compiling the dftables.c program
1832    which is run to generate the source of the default character tables. They
1833    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1834    you will need to set these values.
1836    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1839    Version 3.9 02-Jan-02
1840    ---------------------
1842    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1844    2. If --disable-static was given, the building process failed when trying to
1845    build pcretest and pcregrep. (For some reason it was using libtool to compile
1846    them, which is not right, as they aren't part of the library.)
1849    Version 3.8 18-Dec-01
1850    ---------------------
1852    1. The experimental UTF-8 code was completely screwed up. It was packing the
1853    bytes in the wrong order. How dumb can you get?
1856    Version 3.7 29-Oct-01
1857    ---------------------
1859    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1860    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1861    this didn't happen under Solaris 8, where I normally test things.
1863    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1864    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1865    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1866    this fix an hour or so after the initial 3.7 release.)
1869    Version 3.6 23-Oct-01
1870    ---------------------
1872    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1873    offsets passed as NULL with zero offset count.
1875    2. The config.guess and config.sub files had not been updated when I moved to
1876    the latest autoconf.
1879    Version 3.5 15-Aug-01
1880    ---------------------
1882    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1883    had been forgotten.
1885    2. By using declared but undefined structures, we can avoid using "void"
1886    definitions in pcre.h while keeping the internal definitions of the structures
1887    private.
1889    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1890    user point of view, this means that both static and shared libraries are built
1891    by default, but this can be individually controlled. More of the work of
1892    handling this static/shared cases is now inside libtool instead of PCRE's make
1893    file.
1895    4. The pcretest utility is now installed along with pcregrep because it is
1896    useful for users (to test regexs) and by doing this, it automatically gets
1897    relinked by libtool. The documentation has been turned into a man page, so
1898    there are now .1, .txt, and .html versions in /doc.
1900    5. Upgrades to pcregrep:
1901       (i)   Added long-form option names like gnu grep.
1902       (ii)  Added --help to list all options with an explanatory phrase.
1903       (iii) Added -r, --recursive to recurse into sub-directories.
1904       (iv)  Added -f, --file to read patterns from a file.
1906    6. pcre_exec() was referring to its "code" argument before testing that
1907    argument for NULL (and giving an error if it was NULL).
1909    7. Upgraded Makefile.in to allow for compiling in a different directory from
1910    the source directory.
1912    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1913    options bits, the pointer it was passed was to an int instead of to an unsigned
1914    long int. This mattered only on 64-bit systems.
1916    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1917    generated) instead of pcre.in, which it its source. Also made the same change
1918    in several of the .c files.
1920    10. A new release of gcc defines printf() as a macro, which broke pcretest
1921    because it had an ifdef in the middle of a string argument for printf(). Fixed
1922    by using separate calls to printf().
1924    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1925    script, to force use of CR or LF instead of \n in the source. On non-Unix
1926    systems, the value can be set in config.h.
1928    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1929    absolute limit. Changed the text of the error message to make this clear, and
1930    likewise updated the man page.
1932    13. The limit of 99 on the number of capturing subpatterns has been removed.
1933    The new limit is 65535, which I hope will not be a "real" limit.
1936    Version 3.4 22-Aug-00
1937    ---------------------
1939    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1941    2. Diagnose condition (?(0) as an error instead of crashing on matching.
1944    Version 3.3 01-Aug-00
1945    ---------------------
1947    1. If an octal character was given, but the value was greater than \377, it
1948    was not getting masked to the least significant bits, as documented. This could
1949    lead to crashes in some systems.
1951    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
1952    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
1954    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
1955    These just pass their arguments on to (pcre_free)(), but they are provided
1956    because some uses of PCRE bind it to non-C systems that can call its functions,
1957    but cannot call free() or pcre_free() directly.
1959    4. Add "make test" as a synonym for "make check". Corrected some comments in
1960    the Makefile.
1962    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
1963    Makefile.
1965    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
1966    command called pgrep for grepping around the active processes.
1968    7. Added the beginnings of support for UTF-8 character strings.
1970    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
1971    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
1972    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
1973    out for the ar command.)
1976    Version 3.2 12-May-00
1977    ---------------------
1979    This is purely a bug fixing release.
1981    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
1982    of ZA. This was just one example of several cases that could provoke this bug,
1983    which was introduced by change 9 of version 2.00. The code for breaking
1984    infinite loops after an iteration that matches an empty string was't working
1985    correctly.
1987    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
1988    when matched against abbab (for example). After matching an empty string, it
1989    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
1990    caused it to match further down the string than it should.
1992    3. The code contained an inclusion of sys/types.h. It isn't clear why this
1993    was there because it doesn't seem to be needed, and it causes trouble on some
1994    systems, as it is not a Standard C header. It has been removed.
1996    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
1997    were reported on the Macintosh. The changes were from
1999      while ((c = *(++ptr)) != 0 && c != '\n');
2000    to
2001      while ((c = *(++ptr)) != 0 && c != '\n') ;
2003    Totally extraordinary, but if that's what it takes...
2005    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2006    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2007    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2008    assumes the way PCRE uses memmove() (always moving upwards).
2010    6. PCRE is being used in one environment where strchr() is not available. There
2011    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2012    faster code anyway.
2015    Version 3.1 09-Feb-00
2016    ---------------------
2018    The only change in this release is the fixing of some bugs in Makefile.in for
2019    the "install" target:
2021    (1) It was failing to install pcreposix.h.
2023    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2026    Version 3.0 01-Feb-00
2027    ---------------------
2029    1. Add support for the /+ modifier to perltest (to output $` like it does in
2030    pcretest).
2032    2. Add support for the /g modifier to perltest.
2034    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2035    matches null strings.
2037    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2038    pattern. Perl treats empty patterns specially - it reuses the most recent
2039    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2040    effect.
2042    5. The POSIX interface was broken in that it was just handing over the POSIX
2043    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2044    required a bigger vector, with some working space on the end. This means that
2045    the POSIX wrapper now has to get and free some memory, and copy the results.
2047    6. Added some simple autoconf support, placing the test data and the
2048    documentation in separate directories, re-organizing some of the
2049    information files, and making it build pcre-config (a GNU standard). Also added
2050    libtool support for building PCRE as a shared library, which is now the
2051    default.
2053    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2054    09 are not valid octal constants. Single digits will be used for minor values
2055    less than 10.
2057    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2058    existing programs that set these in the POSIX interface can use PCRE without
2059    modification.
2061    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2062    return all that pcre_info() returns, plus additional data. The pcre_info()
2063    function is retained for compatibility, but is considered to be obsolete.
2065    10. Added experimental recursion feature (?R) to handle one common case that
2066    Perl 5.6 will be able to do with (?p{...}).
2068    11. Added support for POSIX character classes like [:alpha:], which Perl is
2069    adopting.
2072    Version 2.08 31-Aug-99
2073    ----------------------
2075    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2076    trying to match at the startoffset position, but instead was moving forward to
2077    the next newline as if a previous match had failed.
2079    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2080    and could get into a loop if a null string was matched other than at the start
2081    of the subject.
2083    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2084    be distinguished at compile time, and for completeness also added PCRE_DATE.
2086    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2087    in GnuWin32 environments.
2090    Version 2.07 29-Jul-99
2091    ----------------------
2093    1. The documentation is now supplied in plain text form and HTML as well as in
2094    the form of man page sources.
2096    2. C++ compilers don't like assigning (void *) values to other pointer types.
2097    In particular this affects malloc(). Although there is no problem in Standard
2098    C, I've put in casts to keep C++ compilers happy.
2100    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2101    should be (const char *).
2103    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2104    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2105    However, I haven't made this a standard facility. The documentation doesn't
2106    mention it, and the Makefile doesn't support it.
2108    5. The Makefile now contains an "install" target, with editable destinations at
2109    the top of the file. The pcretest program is not installed.
2111    6. pgrep -V now gives the PCRE version number and date.
2113    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2114    causing the entire string to be ignored, instead of just the last character.
2116    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2117    non-matching string, it can take a very, very long time, even for strings of
2118    quite modest length, because of the nested recursion. PCRE now does better in
2119    some of these cases. It does this by remembering the last required literal
2120    character in the pattern, and pre-searching the subject to ensure it is present
2121    before running the real match. In other words, it applies a heuristic to detect
2122    some types of certain failure quickly, and in the above example, if presented
2123    with a string that has no trailing " it gives "no match" very quickly.
2125    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2126    other alternatives are tried instead.
2129    Version 2.06 09-Jun-99
2130    ----------------------
2132    1. Change pcretest's output for amount of store used to show just the code
2133    space, because the remainder (the data block) varies in size between 32-bit and
2134    64-bit systems.
2136    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2137    start matching at. This allows lookbehinds to work when searching for multiple
2138    occurrences in a string.
2140    3. Added additional options to pcretest for testing multiple occurrences:
2142       /+   outputs the rest of the string that follows a match
2143       /g   loops for multiple occurrences, using the new startoffset argument
2144       /G   loops for multiple occurrences by passing an incremented pointer
2146    4. PCRE wasn't doing the "first character" optimization for patterns starting
2147    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2148    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2149    the letter 'x'. On long subject strings, this gives a significant speed-up.
2152    Version 2.05 21-Apr-99
2153    ----------------------
2155    1. Changed the type of magic_number from int to long int so that it works
2156    properly on 16-bit systems.
2158    2. Fixed a bug which caused patterns starting with .* not to work correctly
2159    when the subject string contained newline characters. PCRE was assuming
2160    anchoring for such patterns in all cases, which is not correct because .* will
2161    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2162    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2163    must be retried after every newline in the subject.
2166    Version 2.04 18-Feb-99
2167    ----------------------
2169    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2170    computation of the store needed to hold the pattern was incorrect (too large).
2171    If such patterns were nested a few deep, this could multiply and become a real
2172    problem.
2174    2. Added /M option to pcretest to show the memory requirement of a specific
2175    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2177    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2178    compiled in such a way that the backtracking after subsequent failure was
2179    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2180    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2183    Version 2.03 02-Feb-99
2184    ----------------------
2186    1. Fixed typo and small mistake in man page.
2188    2. Added 4th condition (GPL supersedes if conflict) and created separate
2189    LICENCE file containing the conditions.
2191    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2192    Perl, that is the internal \ allows the delimiter to be included in the
2193    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2194    the final delimiter, add \ to the end of the pattern (to test the error).
2196    4. Added the convenience functions for extracting substrings after a successful
2197    match. Updated pcretest to make it able to test these functions.
2200    Version 2.02 14-Jan-99
2201    ----------------------
2203    1. Initialized the working variables associated with each extraction so that
2204    their saving and restoring doesn't refer to uninitialized store.
2206    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2207    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2208    fix the problem.
2210    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2211    calls, and wasn't printing the correct value for compiling calls. Increased the
2212    default value of LOOPREPEAT, and the number of significant figures in the
2213    times.
2215    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2217    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2218    a building problem on Windows NT with a FAT file system.
2221    Version 2.01 21-Oct-98
2222    ----------------------
2224    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2225    to character tables built by pcre_maketables() in the current locale. If NULL
2226    is passed, the default tables are used.
2229    Version 2.00 24-Sep-98
2230    ----------------------
2232    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2233    it any more.
2235    2. Allow quantification of (?>) groups, and make it work correctly.
2237    3. The first character computation wasn't working for (?>) groups.
2239    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2240    end of the subject) and add 5.005's \z, which really does match only at the
2241    very end of the subject.
2243    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2245    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2246    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2247    localized options. All options to pcre_study() were also removed.
2249    7. Add other new features from 5.005:
2251       $(?<=           positive lookbehind
2252       $(?<!           negative lookbehind
2253       (?imsx-imsx)    added the unsetting capability
2254                       such a setting is global if at outer level; local otherwise
2255       (?imsx-imsx:)   non-capturing groups with option setting
2256       (?(cond)re|re)  conditional pattern matching
2258       A backreference to itself in a repeated group matches the previous
2259       captured string.
2261    8. General tidying up of studying (both automatic and via "study")
2262    consequential on the addition of new assertions.
2264    9. As in 5.005, unlimited repeated groups that could match an empty substring
2265    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2266    runtime if any iteration does actually match an empty substring.
2268    10. Include the RunTest script in the distribution.
2270    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2271    discrepancies, some of which were old and were also with respect to 5.004. They
2272    have now been fixed.
2275    Version 1.09 28-Apr-98
2276    ----------------------
2278    1. A negated single character class followed by a quantifier with a minimum
2279    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2280    program crashes, or just wrong answers. This did not apply to negated classes
2281    containing more than one character, or to minima other than one.
2284  Version 1.08 27-Mar-98  Version 1.08 27-Mar-98
2285  ----------------------  ----------------------

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