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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 8.11 10-Oct-2010
5    ------------------------
7    1.  (*THEN) was not working properly if there were untried alternatives prior
8        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
9        backtracked to try for "b" instead of moving to the next alternative branch
10        at the same level (in this case, to look for "c"). The Perl documentation
11        is clear that when (*THEN) is backtracked onto, it goes to the "next
12        alternative in the innermost enclosing group".
14    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
15        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
16        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
17        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
18        (*THEN).
20    3.  If \s appeared in a character class, it removed the VT character from
21        the class, even if it had been included by some previous item, for example
22        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
23        of \s, but is part of the POSIX "space" class.)
25    4.  A partial match never returns an empty string (because you can always
26        match an empty string at the end of the subject); however the checking for
27        an empty string was starting at the "start of match" point. This has been
28        changed to the "earliest inspected character" point, because the returned
29        data for a partial match starts at this character. This means that, for
30        example, /(?<=abc)def/ gives a partial match for the subject "abc"
31        (previously it gave "no match").
33    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
34        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
35        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
36        has an implication that the given string is incomplete (because a partial
37        match is preferred over a full match). For this reason, these items now
38        give a partial match in this situation. [Aside: previously, the one case
39        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
40        match rather than a full match, which was wrong by the old rules, but is
41        now correct.]
43    6.  There was a bug in the handling of #-introduced comments, recognized when
44        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
45        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
46        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
47        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
48        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
49        places in pcre_compile().
51    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
52        comments when looking ahead for named forward references to subpatterns,
53        the only newline sequence it recognized was NL. It now handles newlines
54        according to the set newline convention.
56    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
57        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
58        cater for a lack of strerror(). These oversights have been fixed.
60    9.  Added --match-limit and --recursion-limit to pcregrep.
62    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
65    Version 8.10 25-Jun-2010
66    ------------------------
68    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
69        THEN.
71    2.  (*ACCEPT) was not working when inside an atomic group.
73    3.  Inside a character class, \B is treated as a literal by default, but
74        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
75        causes the error). The code is unchanged, but I tidied the documentation.
77    4.  Inside a character class, PCRE always treated \R and \X as literals,
78        whereas Perl faults them if its -w option is set. I have changed PCRE so
79        that it faults them when PCRE_EXTRA is set.
81    5.  Added support for \N, which always matches any character other than
82        newline. (It is the same as "." when PCRE_DOTALL is not set.)
84    6.  When compiling pcregrep with newer versions of gcc which may have
85        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
86        declared with attribute warn_unused_result" were given. Just casting the
87        result to (void) does not stop the warnings; a more elaborate fudge is
88        needed. I've used a macro to implement this.
90    7.  Minor change to pcretest.c to avoid a compiler warning.
92    8.  Added four artifical Unicode properties to help with an option to make
93        \s etc use properties (see next item). The new properties are: Xan
94        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
96    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
97        use Unicode properties. (*UCP) at the start of a pattern can be used to set
98        this option. Modified pcretest to add /W to test this facility. Added
99        REG_UCP to make it available via the POSIX interface.
101    10. Added --line-buffered to pcregrep.
103    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
104        studied, and the match started with a letter with a code point greater than
105        127 whose first byte was different to the first byte of the other case of
106        the letter, the other case of this starting letter was not recognized
107        (#976).
109    12. If a pattern that was studied started with a repeated Unicode property
110        test, for example, \p{Nd}+, there was the theoretical possibility of
111        setting up an incorrect bitmap of starting bytes, but fortunately it could
112        not have actually happened in practice until change 8 above was made (it
113        added property types that matched character-matching opcodes).
115    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
116        possible starting bytes for non-anchored patterns.
118    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
119        \R, and also a number of cases that involve Unicode properties, both
120        explicit and implicit when PCRE_UCP is set.
122    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
123        input, it could crash or give wrong results if characters with values
124        greater than 0xc0 were present in the subject string. (Detail: it assumed
125        UTF-8 input when processing these items.)
127    16. Added a lot of (int) casts to avoid compiler warnings in systems where
128        size_t is 64-bit (#991).
130    17. Added a check for running out of memory when PCRE is compiled with
131        --disable-stack-for-recursion (#990).
133    18. If the last data line in a file for pcretest does not have a newline on
134        the end, a newline was missing in the output.
136    19. The default pcre_chartables.c file recognizes only ASCII characters (values
137        less than 128) in its various bitmaps. However, there is a facility for
138        generating tables according to the current locale when PCRE is compiled. It
139        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
140        characters, are recognized by isspace() and therefore were getting set in
141        these tables, and indeed these tables seem to approximate to ISO 8859. This
142        caused a problem in UTF-8 mode when pcre_study() was used to create a list
143        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
144        which of course cannot start UTF-8 characters. I have changed the code so
145        that only real ASCII characters (less than 128) and the correct starting
146        bytes for UTF-8 encodings are set for characters greater than 127 when in
147        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
148        altogether.)
150    20. Added the /T option to pcretest so as to be able to run tests with non-
151        standard character tables, thus making it possible to include the tests
152        used for 19 above in the standard set of tests.
154    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
155        reference to a subpattern the other side of a comment that contains an
156        opening parenthesis caused either an internal compiling error, or a
157        reference to the wrong subpattern.
160    Version 8.02 19-Mar-2010
161    ------------------------
163    1.  The Unicode data tables have been updated to Unicode 5.2.0.
165    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
166        configured.
168    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
169        original author of that file, following a query about its status.
171    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
172        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
174    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
175        quantifier applied to a forward-referencing subroutine call, could compile
176        incorrect code or give the error "internal error: previously-checked
177        referenced subpattern not found".
179    6.  Both MS Visual Studio and Symbian OS have problems with initializing
180        variables to point to external functions. For these systems, therefore,
181        pcre_malloc etc. are now initialized to local functions that call the
182        relevant global functions.
184    7.  There were two entries missing in the vectors called coptable and poptable
185        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
186        I've fixed the data, and added a kludgy way of testing at compile time that
187        the lengths are correct (equal to the number of opcodes).
189    8.  Following on from 7, I added a similar kludge to check the length of the
190        eint vector in pcreposix.c.
192    9.  Error texts for pcre_compile() are held as one long string to avoid too
193        much relocation at load time. To find a text, the string is searched,
194        counting zeros. There was no check for running off the end of the string,
195        which could happen if a new error number was added without updating the
196        string.
198    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
200    11. \K was not working if it appeared in an atomic group or in a group that
201        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
202        \K is "not well defined" if used in an assertion. PCRE now accepts it if
203        the assertion is positive, but not if it is negative.
205    12. Change 11 fortuitously reduced the size of the stack frame used in the
206        "match()" function of pcre_exec.c by one pointer. Forthcoming
207        implementation of support for (*MARK) will need an extra pointer on the
208        stack; I have reserved it now, so that the stack frame size does not
209        decrease.
211    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
212        item in branch that calls a recursion is a subroutine call - as in the
213        second branch in the above example - was incorrectly given the compile-
214        time error "recursive call could loop indefinitely" because pcre_compile()
215        was not correctly checking the subroutine for matching a non-empty string.
217    14. The checks for overrunning compiling workspace could trigger after an
218        overrun had occurred. This is a "should never occur" error, but it can be
219        triggered by pathological patterns such as hundreds of nested parentheses.
220        The checks now trigger 100 bytes before the end of the workspace.
222    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
225    Version 8.01 19-Jan-2010
226    ------------------------
228    1.  If a pattern contained a conditional subpattern with only one branch (in
229        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
230        computed the wrong minimum data length (which is of course zero for such
231        subpatterns). This could cause incorrect "no match" results.
233    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
234        the pattern is reset in the first branch, pcre_compile() failed with
235        "internal error: code overflow at offset...". This happened only when
236        the reset was to the original external option setting. (An optimization
237        abstracts leading options settings into an external setting, which was the
238        cause of this.)
240    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
241        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
242        assertion pattern did not match (meaning that the assertion was true), it
243        was incorrectly treated as false if the SKIP had been reached during the
244        matching. This also applied to assertions used as conditions.
246    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
247        assertion subpattern, including such a pattern used as a condition,
248        unpredictable results occurred, instead of the error return
251    5.  The C++ GlobalReplace function was not working like Perl for the special
252        situation when an empty string is matched. It now does the fancy magic
253        stuff that is necessary.
255    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
256        removed. (These were left over from very, very early versions of PCRE.)
258    7.  Some cosmetic changes to the code to make life easier when compiling it
259        as part of something else:
261        (a) Change DEBUG to PCRE_DEBUG.
263        (b) In pcre_compile(), rename the member of the "branch_chain" structure
264            called "current" as "current_branch", to prevent a collision with the
265            Linux macro when compiled as a kernel module.
267        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
268            prevent a collision with the Linux macro when compiled as a kernel
269            module.
271    8.  In pcre_compile() there are some checks for integer overflows that used to
272        cast potentially large values to (double). This has been changed to that
273        when building, a check for int64_t is made, and if it is found, it is used
274        instead, thus avoiding the use of floating point arithmetic. (There is no
275        other use of FP in PCRE.) If int64_t is not found, the fallback is to
276        double.
278    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
279        2005 (difference between two addresses compared to an unsigned value).
281    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
282        custom one, because of the following reported problem in Windows:
284          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
285              under Win32.
286          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
287              therefore missing the function definition.
288          - The compiler thus generates a "C" signature for the test function.
289          - The linker fails to find the "C" function.
290          - PCRE fails to configure if asked to do so against libbz2.
292    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
293        messages were output:
295          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
296          rerunning libtoolize, to keep the correct libtool macros in-tree.
297          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
299        I have done both of these things.
301    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
302        most of the time, it *can* run out if it is given a pattern that contains a
303        runaway infinite recursion. I updated the discussion in the pcrestack man
304        page.
306    13. Now that we have gone to the x.xx style of version numbers, the minor
307        version may start with zero. Using 08 or 09 is a bad idea because users
308        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
309        interpreted as invalid octal numbers. I've updated the previous comment in
310        configure.ac, and also added a check that gives an error if 08 or 09 are
311        used.
313    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
314        causing partial matching to fail when the end of the subject matched \W
315        in a UTF-8 pattern where \W was quantified with a minimum of 3.
317    15. There were some discrepancies between the declarations in pcre_internal.h
318        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
319        their definitions. The declarations used "const uschar *" and the
320        definitions used USPTR. Even though USPTR is normally defined as "const
321        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
322        reported that: "This difference in casting confuses some C++ compilers, for
323        example, SunCC recognizes above declarations as different functions and
324        generates broken code for hbpcre." I have changed the declarations to use
325        USPTR.
327    16. GNU libtool is named differently on some systems. The autogen.sh script now
328        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
329        (FreeBSD).
331    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
332        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
333        comment: "Figure out how to create a longlong from a string: strtoll and
334        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
335        instance, but it only takes 2 args instead of 3!"
337    18. A subtle bug concerned with back references has been fixed by a change of
338        specification, with a corresponding code fix. A pattern such as
339        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
340        refers, was giving matches when it shouldn't. For example, xa=xaaa would
341        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
342        same bug. Such groups have to be quantified to be useful, or contained
343        inside another quantified group. (If there's no repetition, the reference
344        can never match.) The problem arises because, having left the group and
345        moved on to the rest of the pattern, a later failure that backtracks into
346        the group uses the captured value from the final iteration of the group
347        rather than the correct earlier one. I have fixed this in PCRE by forcing
348        any group that contains a reference to itself to be an atomic group; that
349        is, there cannot be any backtracking into it once it has completed. This is
350        similar to recursive and subroutine calls.
353    Version 8.00 19-Oct-09
354    ----------------------
356    1.  The table for translating pcre_compile() error codes into POSIX error codes
357        was out-of-date, and there was no check on the pcre_compile() error code
358        being within the table. This could lead to an OK return being given in
359        error.
361    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
362        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
363        in a Windows environment.
365    3.  The pcregrep --count option prints the count for each file even when it is
366        zero, as does GNU grep. However, pcregrep was also printing all files when
367        --files-with-matches was added. Now, when both options are given, it prints
368        counts only for those files that have at least one match. (GNU grep just
369        prints the file name in this circumstance, but including the count seems
370        more useful - otherwise, why use --count?) Also ensured that the
371        combination -clh just lists non-zero counts, with no names.
373    4.  The long form of the pcregrep -F option was incorrectly implemented as
374        --fixed_strings instead of --fixed-strings. This is an incompatible change,
375        but it seems right to fix it, and I didn't think it was worth preserving
376        the old behaviour.
378    5.  The command line items --regex=pattern and --regexp=pattern were not
379        recognized by pcregrep, which required --regex pattern or --regexp pattern
380        (with a space rather than an '='). The man page documented the '=' forms,
381        which are compatible with GNU grep; these now work.
383    6.  No libpcreposix.pc file was created for pkg-config; there was just
384        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
386    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
387        when UCP support is not needed, by modifying the Python script that
388        generates it from Unicode data files. This should not matter if the module
389        is correctly used as a library, but I received one complaint about 50K of
390        unwanted data. My guess is that the person linked everything into his
391        program rather than using a library. Anyway, it does no harm.
393    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
394        was a minimum greater than 1 for a wide character in a possessive
395        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
396        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
397        character. Chaos in the form of incorrect output or a compiling loop could
398        result.
400    9.  The restrictions on what a pattern can contain when partial matching is
401        requested for pcre_exec() have been removed. All patterns can now be
402        partially matched by this function. In addition, if there are at least two
403        slots in the offset vector, the offset of the earliest inspected character
404        for the match and the offset of the end of the subject are set in them when
405        PCRE_ERROR_PARTIAL is returned.
407    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
408        synonymous with PCRE_PARTIAL, for backwards compatibility, and
409        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
410        and may be more useful for multi-segment matching.
412    11. Partial matching with pcre_exec() is now more intuitive. A partial match
413        used to be given if ever the end of the subject was reached; now it is
414        given only if matching could not proceed because another character was
415        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
416        string "Z", which now yields "no match" instead of "partial match". In the
417        case of pcre_dfa_exec(), "no match" is given if every matching path for the
418        final character ended with (*FAIL).
420    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
421        if the pattern had a "must contain" character that was already found in the
422        earlier partial match, unless partial matching was again requested. For
423        example, with the pattern /dog.(body)?/, the "must contain" character is
424        "g". If the first part-match was for the string "dog", restarting with
425        "sbody" failed. This bug has been fixed.
427    13. The string returned by pcre_dfa_exec() after a partial match has been
428        changed so that it starts at the first inspected character rather than the
429        first character of the match. This makes a difference only if the pattern
430        starts with a lookbehind assertion or \b or \B (\K is not supported by
431        pcre_dfa_exec()). It's an incompatible change, but it makes the two
432        matching functions compatible, and I think it's the right thing to do.
434    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
435        so that the demonstration program is easily available in environments where
436        PCRE has not been installed from source.
438    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
439        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
440        library.
442    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
443        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
444        is not the first non-POSIX option to be added. Clearly some people find
445        these options useful.
447    17. If a caller to the POSIX matching function regexec() passes a non-zero
448        value for nmatch with a NULL value for pmatch, the value of
449        nmatch is forced to zero.
451    18. RunGrepTest did not have a test for the availability of the -u option of
452        the diff command, as RunTest does. It now checks in the same way as
453        RunTest, and also checks for the -b option.
455    19. If an odd number of negated classes containing just a single character
456        interposed, within parentheses, between a forward reference to a named
457        subpattern and the definition of the subpattern, compilation crashed with
458        an internal error, complaining that it could not find the referenced
459        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
460        [The bug was that it was starting one character too far in when skipping
461        over the character class, thus treating the ] as data rather than
462        terminating the class. This meant it could skip too much.]
464    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
465        /g option in pcretest when the pattern contains \K, which makes it possible
466        to have an empty string match not at the start, even when the pattern is
467        anchored. Updated pcretest and pcredemo to use this option.
469    21. If the maximum number of capturing subpatterns in a recursion was greater
470        than the maximum at the outer level, the higher number was returned, but
471        with unset values at the outer level. The correct (outer level) value is
472        now given.
474    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
475        PCRE did not set those parentheses (unlike Perl). I have now found a way to
476        make it do so. The string so far is captured, making this feature
477        compatible with Perl.
479    23. The tests have been re-organized, adding tests 11 and 12, to make it
480        possible to check the Perl 5.10 features against Perl 5.10.
482    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
483        pattern matches a fixed length string. PCRE did not allow this; now it
484        does. Neither allows recursion.
486    25. I finally figured out how to implement a request to provide the minimum
487        length of subject string that was needed in order to match a given pattern.
488        (It was back references and recursion that I had previously got hung up
489        on.) This code has now been added to pcre_study(); it finds a lower bound
490        to the length of subject needed. It is not necessarily the greatest lower
491        bound, but using it to avoid searching strings that are too short does give
492        some useful speed-ups. The value is available to calling programs via
493        pcre_fullinfo().
495    26. While implementing 25, I discovered to my embarrassment that pcretest had
496        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
497        study optimizations had never been tested with that matching function.
498        Oops. What is worse, even when it was passed study data, there was a bug in
499        pcre_dfa_exec() that meant it never actually used it. Double oops. There
500        were also very few tests of studied patterns with pcre_dfa_exec().
502    27. If (?| is used to create subpatterns with duplicate numbers, they are now
503        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
504        on the other side of the coin, they are no longer allowed to have different
505        names, because these cannot be distinguished in PCRE, and this has caused
506        confusion. (This is a difference from Perl.)
508    28. When duplicate subpattern names are present (necessarily with different
509        numbers, as required by 27 above), and a test is made by name in a
510        conditional pattern, either for a subpattern having been matched, or for
511        recursion in such a pattern, all the associated numbered subpatterns are
512        tested, and the overall condition is true if the condition is true for any
513        one of them. This is the way Perl works, and is also more like the way
514        testing by number works.
517    Version 7.9 11-Apr-09
518    ---------------------
520    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
521        (pcretest), all targets were linked against these libraries. This included
522        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
523        libraries. This caused unwanted dependencies to be created. This problem
524        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
525        pcretest is linked with readline.
527    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
528        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
529        moved outside it again, because FALSE and TRUE are already defined in AIX,
530        but BOOL is not.
532    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
533        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
535    4.  The pcregrep documentation said spaces were inserted as well as colons (or
536        hyphens) following file names and line numbers when outputting matching
537        lines. This is not true; no spaces are inserted. I have also clarified the
538        wording for the --colour (or --color) option.
540    5.  In pcregrep, when --colour was used with -o, the list of matching strings
541        was not coloured; this is different to GNU grep, so I have changed it to be
542        the same.
544    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
545        each matching line was coloured. Now it goes on to look for further matches
546        of any of the test patterns, which is the same behaviour as GNU grep.
548    7.  A pattern that could match an empty string could cause pcregrep to loop; it
549        doesn't make sense to accept an empty string match in pcregrep, so I have
550        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
551        seems to be how GNU grep behaves.
553    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
554        start or after a newline", because the conditional assertion was not being
555        correctly handled. The rule now is that both the assertion and what follows
556        in the first alternative must satisfy the test.
558    9.  If auto-callout was enabled in a pattern with a conditional group whose
559        condition was an assertion, PCRE could crash during matching, both with
560        pcre_exec() and pcre_dfa_exec().
562    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
563        used for matching.
565    11. Unicode property support in character classes was not working for
566        characters (bytes) greater than 127 when not in UTF-8 mode.
568    12. Added the -M command line option to pcretest.
570    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
572    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
574    16. Added comments and documentation about mis-use of no_arg in the C++
575        wrapper.
577    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
578        from Martin Jerabek that uses macro names for all relevant character and
579        string constants.
581    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
582        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
583        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
584        these, but not everybody uses configure.
586    19. A conditional group that had only one branch was not being correctly
587        recognized as an item that could match an empty string. This meant that an
588        enclosing group might also not be so recognized, causing infinite looping
589        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
590        with the subject "ab", where knowledge that the repeated group can match
591        nothing is needed in order to break the loop.
593    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
594        exec(), but without supplying a callout function, matching went wrong.
596    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
597        leak if the size of the offset vector was greater than 30. When the vector
598        is smaller, the saved offsets during recursion go onto a local stack
599        vector, but for larger vectors malloc() is used. It was failing to free
600        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
601        error, in fact).
603    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
604        heapframe that is used only when UTF-8 support is enabled. This caused no
605        problem, but was untidy.
607    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
608        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
609        included within another project.
611    24. Steven Van Ingelgem's patches to add more options to the CMake support,
612        slightly modified by me:
614          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
615              not building pcregrep.
617          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
618              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
620    25. Forward references, both numeric and by name, in patterns that made use of
621        duplicate group numbers, could behave incorrectly or give incorrect errors,
622        because when scanning forward to find the reference group, PCRE was not
623        taking into account the duplicate group numbers. A pattern such as
624        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
626    26. Changed a few more instances of "const unsigned char *" to USPTR, making
627        the feature of a custom pointer more persuasive (as requested by a user).
629    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
630        pcretest.c, inside #ifndefs, because it seems they are sometimes already
631        pre-defined.
633    28. Added support for (*UTF8) at the start of a pattern.
635    29. Arrange for flags added by the "release type" setting in CMake to be shown
636        in the configuration summary.
639    Version 7.8 05-Sep-08
640    ---------------------
642    1.  Replaced UCP searching code with optimized version as implemented for Ad
643        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
644        stage table and inline lookup instead of a function, giving speed ups of 2
645        to 5 times on some simple patterns that I tested. Permission was given to
646        distribute the MultiStage2.py script that generates the tables (it's not in
647        the tarball, but is in the Subversion repository).
649    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
650        scripts.
652    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
653        a group with a zero qualifier. The result of the study could be incorrect,
654        or the function might crash, depending on the pattern.
656    4.  Caseless matching was not working for non-ASCII characters in back
657        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
658        It now works when Unicode Property Support is available.
660    5.  In pcretest, an escape such as \x{de} in the data was always generating
661        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
662        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
663        truncation.
665    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
667    7.  Added two (int) casts to pcregrep when printing the difference of two
668        pointers, in case they are 64-bit values.
670    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
671        test 2 if it fails.
673    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
674        and a #define of that name to empty if it is not externally set. This is to
675        allow users of MSVC to set it if necessary.
677    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
678        the convenience functions in the pcre_get.c source file.
680    11. An option change at the start of a pattern that had top-level alternatives
681        could cause overwriting and/or a crash. This command provoked a crash in
682        some environments:
684          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
686        This potential security problem was recorded as CVE-2008-2371.
688    12. For a pattern where the match had to start at the beginning or immediately
689        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
690        pcre_dfa_exec() could read past the end of the passed subject if there was
691        no match. To help with detecting such bugs (e.g. with valgrind), I modified
692        pcretest so that it places the subject at the end of its malloc-ed buffer.
694    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
695        exec() might read past the end of the data buffer in UTF-8 mode.
697    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
698        the data contained the byte 0x85 as part of a UTF-8 character within its
699        first line. This applied both to normal and DFA matching.
701    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
702        /^[^d]*?$/8 failed to match "abc".
704    16. Added a missing copyright notice to pcrecpp_internal.h.
706    17. Make it more clear in the documentation that values returned from
707        pcre_exec() in ovector are byte offsets, not character counts.
709    18. Tidied a few places to stop certain compilers from issuing warnings.
711    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
712        supplied by Stefan Weber. I made a further small update for 7.8 because
713        there is a change of source arrangements: the pcre_searchfuncs.c module is
714        replaced by pcre_ucd.c.
717    Version 7.7 07-May-08
718    ---------------------
720    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
721        a string to a long long, pretend we don't even have a long long." This is
722        done by checking for the strtoq, strtoll, and _strtoi64 functions.
724    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
725        pre-7.6 versions, which defined a global no_arg variable instead of putting
726        it in the RE class. (See also #8 below.)
728    3.  Remove a line of dead code, identified by coverity and reported by Nuno
729        Lopes.
731    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
733        (1) The include/exclude patterns were being applied to the whole pathnames
734            of files, instead of just to the final components.
736        (2) If there was more than one level of directory, the subdirectories were
737            skipped unless they satisfied the include/exclude conditions. This is
738            inconsistent with GNU grep (and could even be seen as contrary to the
739            pcregrep specification - which I improved to make it absolutely clear).
740            The action now is always to scan all levels of directory, and just
741            apply the include/exclude patterns to regular files.
743    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
744        --exclude_dir in the tests to avoid scanning .svn directories.
746    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
747        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
748        doesn't support NULs in patterns.
750    7.  Added some missing "const"s to declarations of static tables in
751        pcre_compile.c and pcre_dfa_exec.c.
753    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
754        caused by fix #2  above. (Subsequently also a second patch to fix the
755        first patch. And a third patch - this was a messy problem.)
757    9.  Applied Craig's patch to remove the use of push_back().
759    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
760        matching function regexec().
762    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
763        which, however, unlike Perl's \g{...}, are subroutine calls, not back
764        references. PCRE supports relative numbers with this syntax (I don't think
765        Oniguruma does).
767    12. Previously, a group with a zero repeat such as (...){0} was completely
768        omitted from the compiled regex. However, this means that if the group
769        was called as a subroutine from elsewhere in the pattern, things went wrong
770        (an internal error was given). Such groups are now left in the compiled
771        pattern, with a new opcode that causes them to be skipped at execution
772        time.
774    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
775        to the way PCRE behaves:
777        (a) A lone ] character is dis-allowed (Perl treats it as data).
779        (b) A back reference to an unmatched subpattern matches an empty string
780            (Perl fails the current match path).
782        (c) A data ] in a character class must be notated as \] because if the
783            first data character in a class is ], it defines an empty class. (In
784            Perl it is not possible to have an empty class.) The empty class []
785            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
786            The negative empty class [^] matches any one character, independently
787            of the DOTALL setting.
789    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
790        non-existent subpattern following a character class starting with ']' and
791        containing () gave an internal compiling error instead of "reference to
792        non-existent subpattern". Fortunately, when the pattern did exist, the
793        compiled code was correct. (When scanning forwards to check for the
794        existencd of the subpattern, it was treating the data ']' as terminating
795        the class, so got the count wrong. When actually compiling, the reference
796        was subsequently set up correctly.)
798    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
799        it was being rejected as not supported by pcre_dfa_exec(), even though
800        other assertions are supported. I have made pcre_dfa_exec() support
801        (*FAIL).
803    16. The implementation of 13c above involved the invention of a new opcode,
804        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
805        cannot be changed at match time, I realized I could make a small
806        improvement to matching performance by compiling OP_ALLANY instead of
807        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
808        on the OP_ANY path.
810    17. Compiling pcretest on Windows with readline support failed without the
811        following two fixes: (1) Make the unistd.h include conditional on
812        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
814    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
815        ncurses library to be included for pcretest when ReadLine support is
816        requested, but also to allow for it to be overridden. This patch came from
817        Daniel Bergström.
819    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
820        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
821        any errors with the current Unicode tables. Thanks to Peter Kankowski for
822        spotting this.
825    Version 7.6 28-Jan-08
826    ---------------------
828    1.  A character class containing a very large number of characters with
829        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
830        overflow.
832    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
833        HAVE_LONG_LONG is not defined.
835    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
836        bring them up to date and include new features. This patch includes:
838        - Fixed PH's badly added libz and libbz2 support.
839        - Fixed a problem with static linking.
840        - Added pcredemo. [But later removed - see 7 below.]
841        - Fixed dftables problem and added an option.
842        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
843            HAVE_LONG_LONG.
844        - Added readline support for pcretest.
845        - Added an listing of the option settings after cmake has run.
847    4.  A user submitted a patch to Makefile that makes it easy to create
848        "pcre.dll" under mingw when using Configure/Make. I added stuff to
849        Makefile.am that cause it to include this special target, without
850        affecting anything else. Note that the same mingw target plus all
851        the other distribution libraries and programs are now supported
852        when configuring with CMake (see 6 below) instead of with
853        Configure/Make.
855    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
856        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
857        exported in the Windows port". It has not yet been confirmed that the patch
858        solves the problem, but it does no harm.
860    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
861        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
862        with CMake, and also correct the comment about stack recursion.
864    7.  Remove the automatic building of pcredemo from the ./configure system and
865        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
866        of a program that users should build themselves after PCRE is installed, so
867        building it automatically is not really right. What is more, it gave
868        trouble in some build environments.
870    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
873    Version 7.5 10-Jan-08
874    ---------------------
876    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
877        values in parens when parsing an RE using the C++ wrapper."
879    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
880        Characters greater than 255 were excluded from the class instead of being
881        included.
883    3.  The same bug as (2) above applied to negated POSIX classes such as
884        [:^space:].
886    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
887        defined or documented. It seems to have been a typo for PCRE_STATIC, so
888        I have changed it.
890    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
891        first named subpattern) and a construct such as (?&a) would reference the
892        first named subpattern whose name started with "a" (in other words, the
893        length check was missing). Both these problems are fixed. "Subpattern name
894        expected" is now given for (?&) (a zero-length name), and this patch also
895        makes it give the same error for \k'' (previously it complained that that
896        was a reference to a non-existent subpattern).
898    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
899        this is right because (?- can be followed by option settings as well as by
900        digits. I have, however, made the messages clearer.
902    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
903        than the number used in the conditional) now cause a compile-time error.
904        This is actually not compatible with Perl, which accepts such patterns, but
905        treats the conditional as always being FALSE (as PCRE used to), but it
906        seems to me that giving a diagnostic is better.
908    8.  Change "alphameric" to the more common word "alphanumeric" in comments
909        and messages.
911    9.  Fix two occurrences of "backslash" in comments that should have been
912        "backspace".
914    10. Remove two redundant lines of code that can never be obeyed (their function
915        was moved elsewhere).
917    11. The program that makes PCRE's Unicode character property table had a bug
918        which caused it to generate incorrect table entries for sequences of
919        characters that have the same character type, but are in different scripts.
920        It amalgamated them into a single range, with the script of the first of
921        them. In other words, some characters were in the wrong script. There were
922        thirteen such cases, affecting characters in the following ranges:
924          U+002b0 - U+002c1
925          U+0060c - U+0060d
926          U+0061e - U+00612
927          U+0064b - U+0065e
928          U+0074d - U+0076d
929          U+01800 - U+01805
930          U+01d00 - U+01d77
931          U+01d9b - U+01dbf
932          U+0200b - U+0200f
933          U+030fc - U+030fe
934          U+03260 - U+0327f
935          U+0fb46 - U+0fbb1
936          U+10450 - U+1049d
938    12. The -o option (show only the matching part of a line) for pcregrep was not
939        compatible with GNU grep in that, if there was more than one match in a
940        line, it showed only the first of them. It now behaves in the same way as
941        GNU grep.
943    13. If the -o and -v options were combined for pcregrep, it printed a blank
944        line for every non-matching line. GNU grep prints nothing, and pcregrep now
945        does the same. The return code can be used to tell if there were any
946        non-matching lines.
948    14. Added --file-offsets and --line-offsets to pcregrep.
950    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
951        infinitely looping recursion. The bug was that positive lookaheads were not
952        being skipped when checking for a possible empty match (negative lookaheads
953        and both kinds of lookbehind were skipped).
955    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
956        inclusion of <windows.h> to before rather than after the definition of
957        INVALID_FILE_ATTRIBUTES (patch from David Byron).
959    17. Specifying a possessive quantifier with a specific limit for a Unicode
960        character property caused pcre_compile() to compile bad code, which led at
961        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
962        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
963        caused the error; without that there was no problem.
965    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
967    19. Added --enable-pcretest-libreadline.
969    20. In pcrecpp.cc, the variable 'count' was incremented twice in
970        RE::GlobalReplace(). As a result, the number of replacements returned was
971        double what it should be. I removed one of the increments, but Craig sent a
972        later patch that removed the other one (the right fix) and added unit tests
973        that check the return values (which was not done before).
975    21. Several CMake things:
977        (1) Arranged that, when cmake is used on Unix, the libraries end up with
978            the names libpcre and libpcreposix, not just pcre and pcreposix.
980        (2) The above change means that pcretest and pcregrep are now correctly
981            linked with the newly-built libraries, not previously installed ones.
985    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
986        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
987        UTF-8 newline character). The key issue is that the pattern starts .*;
988        this means that the match must be either at the beginning, or after a
989        newline. The bug was in the code for advancing after a failed match and
990        checking that the new position followed a newline. It was not taking
991        account of UTF-8 characters correctly.
993    23. PCRE was behaving differently from Perl in the way it recognized POSIX
994        character classes. PCRE was not treating the sequence [:...:] as a
995        character class unless the ... were all letters. Perl, however, seems to
996        allow any characters between [: and :], though of course it rejects as
997        unknown any "names" that contain non-letters, because all the known class
998        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
999        for example, whereas PCRE did not - it did not recognize a POSIX character
1000        class. This seemed a bit dangerous, so the code has been changed to be
1001        closer to Perl. The behaviour is not identical to Perl, because PCRE will
1002        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
1003        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
1004        Perl does, and where it didn't before.
1006    24. Rewrite so as to remove the single use of %n from pcregrep because in some
1007        Windows environments %n is disabled by default.
1010    Version 7.4 21-Sep-07
1011    ---------------------
1013    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
1014        means that a class such as [\s] counted as "explicit reference to CR or
1015        LF". That isn't really right - the whole point of the change was to try to
1016        help when there was an actual mention of one of the two characters. So now
1017        the change happens only if \r or \n (or a literal CR or LF) character is
1018        encountered.
1020    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
1021        of both had grown to the point where there were only 3 bits left.
1022        Fortunately, there was spare space in the data structure, and so I have
1023        moved the internal flags into a new 16-bit field to free up more option
1024        bits.
1026    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
1027        but did not set the internal JCHANGED flag - either of these is enough to
1028        control the way the "get" function works - but the PCRE_INFO_JCHANGED
1029        facility is supposed to tell if (?J) was ever used, so now (?J) at the
1030        start sets both bits.
1032    4.  Added options (at build time, compile time, exec time) to change \R from
1033        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
1035    5.  doc/pcresyntax.html was missing from the distribution.
1037    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
1038        compatibility, even though it is no longer used.
1040    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
1041        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
1042        windows.h file is present (where different names are used). [This was
1043        reversed later after testing - see 16 below.]
1045    8.  Changed all #include <config.h> to #include "config.h". There were also
1046        some further <pcre.h> cases that I changed to "pcre.h".
1048    9.  When pcregrep was used with the --colour option, it missed the line ending
1049        sequence off the lines that it output.
1051    10. It was pointed out to me that arrays of string pointers cause lots of
1052        relocations when a shared library is dynamically loaded. A technique of
1053        using a single long string with a table of offsets can drastically reduce
1054        these. I have refactored PCRE in four places to do this. The result is
1055        dramatic:
1057          Originally:                          290
1058          After changing UCP table:            187
1059          After changing error message table:   43
1060          After changing table of "verbs"       36
1061          After changing table of Posix names   22
1063        Thanks to the folks working on Gregex for glib for this insight.
1065    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
1066        unicode-properties was also set.
1068    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
1070    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
1071        checked only for CRLF.
1073    14. Added casts to pcretest.c to avoid compiler warnings.
1075    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
1077    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
1078        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
1079        entirely. This removes changes made in 7 above.
1081    17. The CMake files have been updated, and there is now more information about
1082        building with CMake in the NON-UNIX-USE document.
1085    Version 7.3 28-Aug-07
1086    ---------------------
1088     1. In the rejigging of the build system that eventually resulted in 7.1, the
1089        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
1090        brackets there is not right, since it causes compilers to look for an
1091        installed pcre.h, not the version that is in the source that is being
1092        compiled (which of course may be different). I have changed it back to:
1094          #include "pcre.h"
1096        I have a vague recollection that the change was concerned with compiling in
1097        different directories, but in the new build system, that is taken care of
1098        by the VPATH setting the Makefile.
1100     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
1101        when the subject happened to end in the byte 0x85 (e.g. if the last
1102        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
1103        characters but of course it shouldn't be taken as a newline when it is part
1104        of another character. The bug was that, for an unlimited repeat of . in
1105        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
1106        characters when looking for a newline.
1108     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
1110     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
1111        in debug output.
1113     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
1114        long printing in the pcrecpp unittest when running under MinGW.
1116     6. ESC_K was left out of the EBCDIC table.
1118     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
1119        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
1120        limit also applies to "virtual nesting" when a pattern is recursive, and in
1121        this case 1000 isn't so big. I have been able to remove this limit at the
1122        expense of backing off one optimization in certain circumstances. Normally,
1123        when pcre_exec() would call its internal match() function recursively and
1124        immediately return the result unconditionally, it uses a "tail recursion"
1125        feature to save stack. However, when a subpattern that can match an empty
1126        string has an unlimited repetition quantifier, it no longer makes this
1127        optimization. That gives it a stack frame in which to save the data for
1128        checking that an empty string has been matched. Previously this was taken
1129        from the 1000-entry workspace that had been reserved. So now there is no
1130        explicit limit, but more stack is used.
1132     8. Applied Daniel's patches to solve problems with the import/export magic
1133        syntax that is required for Windows, and which was going wrong for the
1134        pcreposix and pcrecpp parts of the library. These were overlooked when this
1135        problem was solved for the main library.
1137     9. There were some crude static tests to avoid integer overflow when computing
1138        the size of patterns that contain repeated groups with explicit upper
1139        limits. As the maximum quantifier is 65535, the maximum group length was
1140        set at 30,000 so that the product of these two numbers did not overflow a
1141        32-bit integer. However, it turns out that people want to use groups that
1142        are longer than 30,000 bytes (though not repeat them that many times).
1143        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
1144        made it possible to implement the integer overflow checks in a much more
1145        dynamic way, which I have now done. The artificial limitation on group
1146        length has been removed - we now have only the limit on the total length of
1147        the compiled pattern, which depends on the LINK_SIZE setting.
1149    10. Fixed a bug in the documentation for get/copy named substring when
1150        duplicate names are permitted. If none of the named substrings are set, the
1151        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
1152        empty string.
1154    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
1155        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
1156        because the ] is interpreted as the first data character and the
1157        terminating ] is not found. PCRE has been made compatible with Perl in this
1158        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
1159        cause memory overwriting.
1161    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
1162        string has been matched (to stop an infinite loop). It was not recognizing
1163        a conditional subpattern that could match an empty string if that
1164        subpattern was within another subpattern. For example, it looped when
1165        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
1166        condition was not nested. This bug has been fixed.
1168    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
1169        past the start of the subject in the presence of bytes with the top bit
1170        set, for example "\x8aBCD".
1172    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
1173        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
1175    14. Optimized (?!) to (*FAIL).
1177    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
1178        This restricts code points to be within the range 0 to 0x10FFFF, excluding
1179        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
1180        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
1181        does: it's just the validity check that is more restrictive.
1183    16. Inserted checks for integer overflows during escape sequence (backslash)
1184        processing, and also fixed erroneous offset values for syntax errors during
1185        backslash processing.
1187    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
1188        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
1190    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
1191        caused an overrun.
1193    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
1194        something other than just ASCII characters) inside a group that had an
1195        unlimited repeat caused a loop at compile time (while checking to see
1196        whether the group could match an empty string).
1198    20. Debugging a pattern containing \p or \P could cause a crash. For example,
1199        [\P{Any}] did so. (Error in the code for printing property names.)
1201    21. An orphan \E inside a character class could cause a crash.
1203    22. A repeated capturing bracket such as (A)? could cause a wild memory
1204        reference during compilation.
1206    23. There are several functions in pcre_compile() that scan along a compiled
1207        expression for various reasons (e.g. to see if it's fixed length for look
1208        behind). There were bugs in these functions when a repeated \p or \P was
1209        present in the pattern. These operators have additional parameters compared
1210        with \d, etc, and these were not being taken into account when moving along
1211        the compiled data. Specifically:
1213        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
1214            length.
1216        (b) An item such as \pL+ within a repeated group could cause crashes or
1217            loops.
1219        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
1220            "reference to non-existent subpattern" error.
1222        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
1224    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
1225        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
1227    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
1229    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
1230        character were causing crashes (broken optimization).
1232    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
1233        \p or \P) caused a compile-time loop.
1235    28. More problems have arisen in unanchored patterns when CRLF is a valid line
1236        break. For example, the unstudied pattern [\r\n]A does not match the string
1237        "\r\nA" because change 7.0/46 below moves the current point on by two
1238        characters after failing to match at the start. However, the pattern \nA
1239        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
1240        the same is true. There doesn't seem any very clean way out of this, but
1241        what I have chosen to do makes the common cases work: PCRE now takes note
1242        of whether there can be an explicit match for \r or \n anywhere in the
1243        pattern, and if so, 7.0/46 no longer applies. As part of this change,
1244        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
1245        pattern has explicit CR or LF references.
1247    29. Added (*CR) etc for changing newline setting at start of pattern.
1250    Version 7.2 19-Jun-07
1251    ---------------------
1253     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
1254        which is apparently normally available under Windows.
1256     2. Re-jig the pcregrep tests with different newline settings in an attempt
1257        to make them independent of the local environment's newline setting.
1259     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
1261     4. Some of the "internals" tests were previously cut out when the link size
1262        was not 2, because the output contained actual offsets. The recent new
1263        "Z" feature of pcretest means that these can be cut out, making the tests
1264        usable with all link sizes.
1266     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
1267        stack recursion. This gives a massive performance boost under BSD, but just
1268        a small improvement under Linux. However, it saves one field in the frame
1269        in all cases.
1271     6. Added more features from the forthcoming Perl 5.10:
1273        (a) (?-n) (where n is a string of digits) is a relative subroutine or
1274            recursion call. It refers to the nth most recently opened parentheses.
1276        (b) (?+n) is also a relative subroutine call; it refers to the nth next
1277            to be opened parentheses.
1279        (c) Conditions that refer to capturing parentheses can be specified
1280            relatively, for example, (?(-2)... or (?(+3)...
1282        (d) \K resets the start of the current match so that everything before
1283            is not part of it.
1285        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
1287        (f) \g{name} is another synonym - part of Perl 5.10's unification of
1288            reference syntax.
1290        (g) (?| introduces a group in which the numbering of parentheses in each
1291            alternative starts with the same number.
1293        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
1295     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
1298     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
1299        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
1300        for detecting groups that can match an empty string.
1302     9. A pattern with a very large number of alternatives (more than several
1303        hundred) was running out of internal workspace during the pre-compile
1304        phase, where pcre_compile() figures out how much memory will be needed. A
1305        bit of new cunning has reduced the workspace needed for groups with
1306        alternatives. The 1000-alternative test pattern now uses 12 bytes of
1307        workspace instead of running out of the 4096 that are available.
1309    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
1311    11. Applied patch from Google to remove an optimization that didn't quite work.
1312        The report of the bug said:
1314          pcrecpp::RE("a*").FullMatch("aaa") matches, while
1315          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
1316          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
1318    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
1319        it matched the wrong number of bytes.
1322    Version 7.1 24-Apr-07
1323    ---------------------
1325     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
1326        that is more "standard", making use of automake and other Autotools. There
1327        is some re-arrangement of the files and adjustment of comments consequent
1328        on this.
1330     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
1331        for recursive directory scanning broke on some systems because the files
1332        are not scanned in any specific order and on different systems the order
1333        was different. A call to "sort" has been inserted into RunGrepTest for the
1334        approprate test as a short-term fix. In the longer term there may be an
1335        alternative.
1337     3. I had an email from Eric Raymond about problems translating some of PCRE's
1338        man pages to HTML (despite the fact that I distribute HTML pages, some
1339        people do their own conversions for various reasons). The problems
1340        concerned the use of low-level troff macros .br and .in. I have therefore
1341        removed all such uses from the man pages (some were redundant, some could
1342        be replaced by .nf/.fi pairs). The 132html script that I use to generate
1343        HTML has been updated to handle .nf/.fi and to complain if it encounters
1344        .br or .in.
1346     4. Updated comments in configure.ac that get placed in config.h.in and also
1347        arranged for config.h to be included in the distribution, with the name
1348        config.h.generic, for the benefit of those who have to compile without
1349        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
1351     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
1352        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
1353        makevp.bat for the current PCRE, using the additional files
1354        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
1356     6. A Windows user reported a minor discrepancy with test 2, which turned out
1357        to be caused by a trailing space on an input line that had got lost in his
1358        copy. The trailing space was an accident, so I've just removed it.
1360     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
1361        that is needed.
1363     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
1364        as "const" (a) because they are and (b) because it helps the PHP
1365        maintainers who have recently made a script to detect big data structures
1366        in the php code that should be moved to the .rodata section. I remembered
1367        to update Builducptable as well, so it won't revert if ucptable.h is ever
1368        re-created.
1370     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
1371        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
1372        order to be able to cut out the UTF-8 tables in the latter when UTF-8
1373        support is not required. This saves 1.5-2K of code, which is important in
1374        some applications.
1376        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
1377        so as not to refer to the tables, even though these functions will never be
1378        called when UTF-8 support is disabled. Otherwise there are problems with a
1379        shared library.
1381    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
1383        (a) It was defining its arguments as char * instead of void *.
1385        (b) It was assuming that all moves were upwards in memory; this was true
1386            a long time ago when I wrote it, but is no longer the case.
1388        The emulated memove() is provided for those environments that have neither
1389        memmove() nor bcopy(). I didn't think anyone used it these days, but that
1390        is clearly not the case, as these two bugs were recently reported.
1392    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
1393        and Detrail to create the HTML documentation, the .txt form of the man
1394        pages, and it removes trailing spaces from listed files. It also creates
1395        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
1396        case, it wraps all the #defines with #ifndefs. This script should be run
1397        before "make dist".
1399    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
1400        with Unicode property support.
1402        (a) For a maximizing quantifier, if the two different cases of the
1403            character were of different lengths in their UTF-8 codings (there are
1404            some cases like this - I found 11), and the matching function had to
1405            back up over a mixture of the two cases, it incorrectly assumed they
1406            were both the same length.
1408        (b) When PCRE was configured to use the heap rather than the stack for
1409            recursion during matching, it was not correctly preserving the data for
1410            the other case of a UTF-8 character when checking ahead for a match
1411            while processing a minimizing repeat. If the check also involved
1412            matching a wide character, but failed, corruption could cause an
1413            erroneous result when trying to check for a repeat of the original
1414            character.
1416    13. Some tidying changes to the testing mechanism:
1418        (a) The RunTest script now detects the internal link size and whether there
1419            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
1420            values substituted by "configure". (The RunGrepTest script already did
1421            this for UTF-8.) The configure.ac script no longer substitutes the
1422            relevant variables.
1424        (b) The debugging options /B and /D in pcretest show the compiled bytecode
1425            with length and offset values. This means that the output is different
1426            for different internal link sizes. Test 2 is skipped for link sizes
1427            other than 2 because of this, bypassing the problem. Unfortunately,
1428            there was also a test in test 3 (the locale tests) that used /B and
1429            failed for link sizes other than 2. Rather than cut the whole test out,
1430            I have added a new /Z option to pcretest that replaces the length and
1431            offset values with spaces. This is now used to make test 3 independent
1432            of link size. (Test 2 will be tidied up later.)
1434    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
1435        segmentation fault instead of returning the appropriate error message.
1437    15. In multiline mode when the newline sequence was set to "any", the pattern
1438        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
1439        This doesn't seem right; it now treats the CRLF combination as the line
1440        ending, and so does not match in that case. It's only a pattern such as ^$
1441        that would hit this one: something like ^ABC$ would have failed after \r
1442        and then tried again after \r\n.
1444    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
1445        in an attempt to make files that differ only in their line terminators
1446        compare equal. This works on Linux.
1448    17. Under certain error circumstances pcregrep might try to free random memory
1449        as it exited. This is now fixed, thanks to valgrind.
1451    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
1452        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
1453        was because its rules for how to advance for /g after matching an empty
1454        string at the end of a line did not allow for this case. They now check for
1455        it specially.
1457    20. pcretest is supposed to handle patterns and data of any length, by
1458        extending its buffers when necessary. It was getting this wrong when the
1459        buffer for a data line had to be extended.
1461    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
1462        CRLF as a newline sequence.
1464    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
1465        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
1466        I have nevertheless tidied it up.
1468    23. Added some casts to kill warnings from HP-UX ia64 compiler.
1470    24. Added a man page for pcre-config.
1473    Version 7.0 19-Dec-06
1474    ---------------------
1476     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
1477        moving to gcc 4.1.1.
1479     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
1480        sys/time.h, which is documented as needed for this function. It doesn't
1481        seem to matter on Linux, but it showed up on some releases of OS X.
1483     3. It seems that there are systems where bytes whose values are greater than
1484        127 match isprint() in the "C" locale. The "C" locale should be the
1485        default when a C program starts up. In most systems, only ASCII printing
1486        characters match isprint(). This difference caused the output from pcretest
1487        to vary, making some of the tests fail. I have changed pcretest so that:
1489        (a) When it is outputting text in the compiled version of a pattern, bytes
1490            other than 32-126 are always shown as hex escapes.
1492        (b) When it is outputting text that is a matched part of a subject string,
1493            it does the same, unless a different locale has been set for the match
1494            (using the /L modifier). In this case, it uses isprint() to decide.
1496     4. Fixed a major bug that caused incorrect computation of the amount of memory
1497        required for a compiled pattern when options that changed within the
1498        pattern affected the logic of the preliminary scan that determines the
1499        length. The relevant options are -x, and -i in UTF-8 mode. The result was
1500        that the computed length was too small. The symptoms of this bug were
1501        either the PCRE error "internal error: code overflow" from pcre_compile(),
1502        or a glibc crash with a message such as "pcretest: free(): invalid next
1503        size (fast)". Examples of patterns that provoked this bug (shown in
1504        pcretest format) are:
1506          /(?-x: )/x
1507          /(?x)(?-x: \s*#\s*)/
1508          /((?i)[\x{c0}])/8
1509          /(?i:[\x{c0}])/8
1511        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
1512        is now done differently.
1514     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
1515        wrapper classes; (b) implement a new function in the C++ scanner that is
1516        more efficient than the old way of doing things because it avoids levels of
1517        recursion in the regex matching; (c) add a paragraph to the documentation
1518        for the FullMatch() function.
1520     6. The escape sequence \n was being treated as whatever was defined as
1521        "newline". Not only was this contrary to the documentation, which states
1522        that \n is character 10 (hex 0A), but it also went horribly wrong when
1523        "newline" was defined as CRLF. This has been fixed.
1525     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
1526        was being set to -1 for the "end of line" case (supposedly a value that no
1527        character can have). Though this value is never used (the check for end of
1528        line is "zero bytes in current character"), it caused compiler complaints.
1529        I've changed it to 0xffffffff.
1531     8. In pcre_version.c, the version string was being built by a sequence of
1532        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
1533        string (as it is for production releases) called a macro with an empty
1534        argument. The C standard says the result of this is undefined. The gcc
1535        compiler treats it as an empty string (which was what was wanted) but it is
1536        reported that Visual C gives an error. The source has been hacked around to
1537        avoid this problem.
1539     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
1540        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
1541        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
1542        of them did).
1544    10. Originally, pcretest opened its input and output without "b"; then I was
1545        told that "b" was needed in some environments, so it was added for release
1546        5.0 to both the input and output. (It makes no difference on Unix-like
1547        systems.) Later I was told that it is wrong for the input on Windows. I've
1548        now abstracted the modes into two macros, to make it easier to fiddle with
1549        them, and removed "b" from the input mode under Windows.
1551    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
1553    12. Added -help and --help to pcretest as an official way of being reminded
1554        of the options.
1556    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
1557        and pcrecpp.cc because they annoy compilers at high warning levels.
1559    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
1561    15. Fixed an occurrence of == in configure.ac that should have been = (shell
1562        scripts are not C programs :-) and which was not noticed because it works
1563        on Linux.
1565    16. pcretest is supposed to handle any length of pattern and data line (as one
1566        line or as a continued sequence of lines) by extending its input buffer if
1567        necessary. This feature was broken for very long pattern lines, leading to
1568        a string of junk being passed to pcre_compile() if the pattern was longer
1569        than about 50K.
1571    17. I have done a major re-factoring of the way pcre_compile() computes the
1572        amount of memory needed for a compiled pattern. Previously, there was code
1573        that made a preliminary scan of the pattern in order to do this. That was
1574        OK when PCRE was new, but as the facilities have expanded, it has become
1575        harder and harder to keep it in step with the real compile phase, and there
1576        have been a number of bugs (see for example, 4 above). I have now found a
1577        cunning way of running the real compile function in a "fake" mode that
1578        enables it to compute how much memory it would need, while actually only
1579        ever using a few hundred bytes of working memory and without too many
1580        tests of the mode. This should make future maintenance and development
1581        easier. A side effect of this work is that the limit of 200 on the nesting
1582        depth of parentheses has been removed (though this was never a serious
1583        limitation, I suspect). However, there is a downside: pcre_compile() now
1584        runs more slowly than before (30% or more, depending on the pattern). I
1585        hope this isn't a big issue. There is no effect on runtime performance.
1587    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1588        newline (only possible for the last line of a file) and it was a
1589        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1591    19. Added additional timing features to pcretest. (1) The -tm option now times
1592        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1593        separate command line item, by a number that specifies the number of
1594        repeats to use when timing. The default is 50000; this gives better
1595        precision, but takes uncomfortably long for very large patterns.
1597    20. Extended pcre_study() to be more clever in cases where a branch of a
1598        subpattern has no definite first character. For example, (a*|b*)[cd] would
1599        previously give no result from pcre_study(). Now it recognizes that the
1600        first character must be a, b, c, or d.
1602    21. There was an incorrect error "recursive call could loop indefinitely" if
1603        a subpattern (or the entire pattern) that was being tested for matching an
1604        empty string contained only one non-empty item after a nested subpattern.
1605        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1606        incorrectly, because the \d was being skipped in the check.
1608    22. The pcretest program now has a new pattern option /B and a command line
1609        option -b, which is equivalent to adding /B to every pattern. This causes
1610        it to show the compiled bytecode, without the additional information that
1611        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1612        is the same as /B/I).
1614    23. A new optimization is now able automatically to treat some sequences such
1615        as a*b as a*+b. More specifically, if something simple (such as a character
1616        or a simple class like \d) has an unlimited quantifier, and is followed by
1617        something that cannot possibly match the quantified thing, the quantifier
1618        is automatically "possessified".
1620    24. A recursive reference to a subpattern whose number was greater than 39
1621        went wrong under certain circumstances in UTF-8 mode. This bug could also
1622        have affected the operation of pcre_study().
1624    25. Realized that a little bit of performance could be had by replacing
1625        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1627    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1629    27. Possessive quantifiers such as a++ were previously implemented by turning
1630        them into atomic groups such as ($>a+). Now they have their own opcodes,
1631        which improves performance. This includes the automatically created ones
1632        from 23 above.
1634    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1635        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1636        the first matched character to be a colon. This applied both to named and
1637        numbered groups.
1639    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1641    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1642        building PCRE on Windows easier, so I have included it in the distribution.
1644    31. There is now a check in pcretest against a ridiculously large number being
1645        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1646        loop, the loop is abandoned.
1648    32. Forward references to subpatterns in conditions such as (?(2)...) where
1649        subpattern 2 is defined later cause pcre_compile() to search forwards in
1650        the pattern for the relevant set of parentheses. This search went wrong
1651        when there were unescaped parentheses in a character class, parentheses
1652        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1654    33. "Subroutine" calls and backreferences were previously restricted to
1655        referencing subpatterns earlier in the regex. This restriction has now
1656        been removed.
1658    34. Added a number of extra features that are going to be in Perl 5.10. On the
1659        whole, these are just syntactic alternatives for features that PCRE had
1660        previously implemented using the Python syntax or my own invention. The
1661        other formats are all retained for compatibility.
1663        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1664            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1665            also .NET compatible.
1667        (b) A recursion or subroutine call to a named group can now be defined as
1668            (?&name) as well as (?P>name).
1670        (c) A backreference to a named group can now be defined as \k<name> or
1671            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1672            5.10, are also .NET compatible.
1674        (d) A conditional reference to a named group can now use the syntax
1675            (?(<name>) or (?('name') as well as (?(name).
1677        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1678            groups (named and numbered) that are never evaluated inline, but can be
1679            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1680            is always false. There may be only one alternative in such a group.
1682        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1683            as the simple (?(R). The condition is true only if the most recent
1684            recursion is that of the given number or name. It does not search out
1685            through the entire recursion stack.
1687        (g) The escape \gN or \g{N} has been added, where N is a positive or
1688            negative number, specifying an absolute or relative reference.
1690    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1691        some "unreachable code" warnings.
1693    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1694        things, this adds five new scripts.
1696    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1697        There were also incompatibilities regarding the handling of \Q..\E inside
1698        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1699        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1701    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1702        matches an empty string, and forcibly breaks the loop. There were bugs in
1703        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1704        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1705        separate and independent bugs (that affected different cases) have been
1706        fixed.
1708    39. Refactored the code to abolish the use of different opcodes for small
1709        capturing bracket numbers. This is a tidy that I avoided doing when I
1710        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1711        The new approach is not only tidier, it makes it possible to reduce the
1712        memory needed to fix the previous bug (38).
1714    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1715        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1716        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1717        mode.
1719    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1720        report.
1722    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1723        copy construction and assignment in the C++ wrapper.
1725    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1726        couple of bugs that could have given wrong results in the "--newline=crlf"
1727        case.
1729    44. Added a number of casts and did some reorganization of signed/unsigned int
1730        variables following suggestions from Dair Grant. Also renamed the variable
1731        "this" as "item" because it is a C++ keyword.
1733    45. Arranged for dftables to add
1735          #include "pcre_internal.h"
1737        to pcre_chartables.c because without it, gcc 4.x may remove the array
1738        definition from the final binary if PCRE is built into a static library and
1739        dead code stripping is activated.
1741    46. For an unanchored pattern, if a match attempt fails at the start of a
1742        newline sequence, and the newline setting is CRLF or ANY, and the next two
1743        characters are CRLF, advance by two characters instead of one.
1746  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
1747  ---------------------  ---------------------

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