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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.00 ??-???-??  Version 8.12 12-Jan-2011
5    ------------------------
6    
7    1.  Fixed some typos in the markup of the man pages, and wrote a script that
8        checks for such things as part of the documentation building process.
9    
10    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
11        --match-limit and --recursion-limit options (added for 8.11). In
12        particular, this made one of the standard tests crash. (The integer value
13        went into the wrong half of a long int.)
14    
15    3.  If the --colour option was given to pcregrep with -v (invert match), it
16        did strange things, either producing crazy output, or crashing. It should,
17        of course, ignore a request for colour when reporting lines that do not
18        match.
19    
20    4.  If pcregrep was compiled under Windows, there was a reference to the
21        function pcregrep_exit() before it was defined. I am assuming this was
22        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
23        reported by a user. I've moved the definition above the reference.
24    
25    
26    Version 8.11 10-Dec-2010
27    ------------------------
28    
29    1.  (*THEN) was not working properly if there were untried alternatives prior
30        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
31        backtracked to try for "b" instead of moving to the next alternative branch
32        at the same level (in this case, to look for "c"). The Perl documentation
33        is clear that when (*THEN) is backtracked onto, it goes to the "next
34        alternative in the innermost enclosing group".
35    
36    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
37        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
38        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
39        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
40        (*THEN).
41    
42    3.  If \s appeared in a character class, it removed the VT character from
43        the class, even if it had been included by some previous item, for example
44        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
45        of \s, but is part of the POSIX "space" class.)
46    
47    4.  A partial match never returns an empty string (because you can always
48        match an empty string at the end of the subject); however the checking for
49        an empty string was starting at the "start of match" point. This has been
50        changed to the "earliest inspected character" point, because the returned
51        data for a partial match starts at this character. This means that, for
52        example, /(?<=abc)def/ gives a partial match for the subject "abc"
53        (previously it gave "no match").
54    
55    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
56        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
57        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
58        has an implication that the given string is incomplete (because a partial
59        match is preferred over a full match). For this reason, these items now
60        give a partial match in this situation. [Aside: previously, the one case
61        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
62        match rather than a full match, which was wrong by the old rules, but is
63        now correct.]
64    
65    6.  There was a bug in the handling of #-introduced comments, recognized when
66        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
67        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
68        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
69        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
70        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
71        places in pcre_compile().
72    
73    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
74        comments when looking ahead for named forward references to subpatterns,
75        the only newline sequence it recognized was NL. It now handles newlines
76        according to the set newline convention.
77    
78    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
79        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
80        cater for a lack of strerror(). These oversights have been fixed.
81    
82    9.  Added --match-limit and --recursion-limit to pcregrep.
83    
84    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
85    
86    11. When the -o option was used, pcregrep was setting a return code of 1, even
87        when matches were found, and --line-buffered was not being honoured.
88    
89    12. Added an optional parentheses number to the -o and --only-matching options
90        of pcregrep.
91    
92    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
93        can match an empty string. The code to do it in pcretest and pcredemo
94        needed fixing:
95    
96        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
97            only one byte after an empty string match just before CRLF (this case
98            just got forgotten; "any" and "anycrlf" were OK).
99    
100        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
101            mode when an empty string match preceded an ASCII character followed by
102            a non-ASCII character. (The code for advancing by one character rather
103            than one byte was nonsense.)
104    
105        (c) The pcredemo.c sample program did not have any code at all to handle
106            the cases when CRLF is a valid newline sequence.
107    
108    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
109        as a starting offset was within the subject string. There is now a new
110        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
111        negative or greater than the length of the string. In order to test this,
112        pcretest is extended to allow the setting of negative starting offsets.
113    
114    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
115        starting offset points to the beginning of a UTF-8 character was
116        unnecessarily clumsy. I tidied it up.
117    
118    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
119        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
120    
121    17. Nobody had reported that the --include_dir option, which was added in
122        release 7.7 should have been called --include-dir (hyphen, not underscore)
123        for compatibility with GNU grep. I have changed it to --include-dir, but
124        left --include_dir as an undocumented synonym, and the same for
125        --exclude-dir, though that is not available in GNU grep, at least as of
126        release 2.5.4.
127    
128    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
129        characters from a string of bytes) have been redefined so as not to use
130        loops, in order to improve performance in some environments. At the same
131        time, I abstracted some of the common code into auxiliary macros to save
132        repetition (this should not affect the compiled code).
133    
134    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
135        compile-time error is now given if \c is not followed by an ASCII
136        character, that is, a byte less than 128. (In EBCDIC mode, the code is
137        different, and any byte value is allowed.)
138    
139    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
140        START_OPTIMIZE option, which is now allowed at compile time - but just
141        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
142        to pcregrep and other applications that have no direct access to PCRE
143        options. The new /Y option in pcretest sets this option when calling
144        pcre_compile().
145    
146    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
147        back references. Groups containing recursive back references were forced to
148        be atomic by that change, but in the case of named groups, the amount of
149        memory required was incorrectly computed, leading to "Failed: internal
150        error: code overflow". This has been fixed.
151    
152    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
153        pcretest.c, to avoid build problems in some Borland environments.
154    
155    
156    Version 8.10 25-Jun-2010
157    ------------------------
158    
159    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
160        THEN.
161    
162    2.  (*ACCEPT) was not working when inside an atomic group.
163    
164    3.  Inside a character class, \B is treated as a literal by default, but
165        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
166        causes the error). The code is unchanged, but I tidied the documentation.
167    
168    4.  Inside a character class, PCRE always treated \R and \X as literals,
169        whereas Perl faults them if its -w option is set. I have changed PCRE so
170        that it faults them when PCRE_EXTRA is set.
171    
172    5.  Added support for \N, which always matches any character other than
173        newline. (It is the same as "." when PCRE_DOTALL is not set.)
174    
175    6.  When compiling pcregrep with newer versions of gcc which may have
176        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
177        declared with attribute warn_unused_result" were given. Just casting the
178        result to (void) does not stop the warnings; a more elaborate fudge is
179        needed. I've used a macro to implement this.
180    
181    7.  Minor change to pcretest.c to avoid a compiler warning.
182    
183    8.  Added four artifical Unicode properties to help with an option to make
184        \s etc use properties (see next item). The new properties are: Xan
185        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
186    
187    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
188        use Unicode properties. (*UCP) at the start of a pattern can be used to set
189        this option. Modified pcretest to add /W to test this facility. Added
190        REG_UCP to make it available via the POSIX interface.
191    
192    10. Added --line-buffered to pcregrep.
193    
194    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
195        studied, and the match started with a letter with a code point greater than
196        127 whose first byte was different to the first byte of the other case of
197        the letter, the other case of this starting letter was not recognized
198        (#976).
199    
200    12. If a pattern that was studied started with a repeated Unicode property
201        test, for example, \p{Nd}+, there was the theoretical possibility of
202        setting up an incorrect bitmap of starting bytes, but fortunately it could
203        not have actually happened in practice until change 8 above was made (it
204        added property types that matched character-matching opcodes).
205    
206    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
207        possible starting bytes for non-anchored patterns.
208    
209    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
210        \R, and also a number of cases that involve Unicode properties, both
211        explicit and implicit when PCRE_UCP is set.
212    
213    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
214        input, it could crash or give wrong results if characters with values
215        greater than 0xc0 were present in the subject string. (Detail: it assumed
216        UTF-8 input when processing these items.)
217    
218    16. Added a lot of (int) casts to avoid compiler warnings in systems where
219        size_t is 64-bit (#991).
220    
221    17. Added a check for running out of memory when PCRE is compiled with
222        --disable-stack-for-recursion (#990).
223    
224    18. If the last data line in a file for pcretest does not have a newline on
225        the end, a newline was missing in the output.
226    
227    19. The default pcre_chartables.c file recognizes only ASCII characters (values
228        less than 128) in its various bitmaps. However, there is a facility for
229        generating tables according to the current locale when PCRE is compiled. It
230        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
231        characters, are recognized by isspace() and therefore were getting set in
232        these tables, and indeed these tables seem to approximate to ISO 8859. This
233        caused a problem in UTF-8 mode when pcre_study() was used to create a list
234        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
235        which of course cannot start UTF-8 characters. I have changed the code so
236        that only real ASCII characters (less than 128) and the correct starting
237        bytes for UTF-8 encodings are set for characters greater than 127 when in
238        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
239        altogether.)
240    
241    20. Added the /T option to pcretest so as to be able to run tests with non-
242        standard character tables, thus making it possible to include the tests
243        used for 19 above in the standard set of tests.
244    
245    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
246        reference to a subpattern the other side of a comment that contains an
247        opening parenthesis caused either an internal compiling error, or a
248        reference to the wrong subpattern.
249    
250    
251    Version 8.02 19-Mar-2010
252    ------------------------
253    
254    1.  The Unicode data tables have been updated to Unicode 5.2.0.
255    
256    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
257        configured.
258    
259    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
260        original author of that file, following a query about its status.
261    
262    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
263        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
264    
265    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
266        quantifier applied to a forward-referencing subroutine call, could compile
267        incorrect code or give the error "internal error: previously-checked
268        referenced subpattern not found".
269    
270    6.  Both MS Visual Studio and Symbian OS have problems with initializing
271        variables to point to external functions. For these systems, therefore,
272        pcre_malloc etc. are now initialized to local functions that call the
273        relevant global functions.
274    
275    7.  There were two entries missing in the vectors called coptable and poptable
276        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
277        I've fixed the data, and added a kludgy way of testing at compile time that
278        the lengths are correct (equal to the number of opcodes).
279    
280    8.  Following on from 7, I added a similar kludge to check the length of the
281        eint vector in pcreposix.c.
282    
283    9.  Error texts for pcre_compile() are held as one long string to avoid too
284        much relocation at load time. To find a text, the string is searched,
285        counting zeros. There was no check for running off the end of the string,
286        which could happen if a new error number was added without updating the
287        string.
288    
289    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
290    
291    11. \K was not working if it appeared in an atomic group or in a group that
292        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
293        \K is "not well defined" if used in an assertion. PCRE now accepts it if
294        the assertion is positive, but not if it is negative.
295    
296    12. Change 11 fortuitously reduced the size of the stack frame used in the
297        "match()" function of pcre_exec.c by one pointer. Forthcoming
298        implementation of support for (*MARK) will need an extra pointer on the
299        stack; I have reserved it now, so that the stack frame size does not
300        decrease.
301    
302    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
303        item in branch that calls a recursion is a subroutine call - as in the
304        second branch in the above example - was incorrectly given the compile-
305        time error "recursive call could loop indefinitely" because pcre_compile()
306        was not correctly checking the subroutine for matching a non-empty string.
307    
308    14. The checks for overrunning compiling workspace could trigger after an
309        overrun had occurred. This is a "should never occur" error, but it can be
310        triggered by pathological patterns such as hundreds of nested parentheses.
311        The checks now trigger 100 bytes before the end of the workspace.
312    
313    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
314    
315    
316    Version 8.01 19-Jan-2010
317    ------------------------
318    
319    1.  If a pattern contained a conditional subpattern with only one branch (in
320        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
321        computed the wrong minimum data length (which is of course zero for such
322        subpatterns). This could cause incorrect "no match" results.
323    
324    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
325        the pattern is reset in the first branch, pcre_compile() failed with
326        "internal error: code overflow at offset...". This happened only when
327        the reset was to the original external option setting. (An optimization
328        abstracts leading options settings into an external setting, which was the
329        cause of this.)
330    
331    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
332        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
333        assertion pattern did not match (meaning that the assertion was true), it
334        was incorrectly treated as false if the SKIP had been reached during the
335        matching. This also applied to assertions used as conditions.
336    
337    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
338        assertion subpattern, including such a pattern used as a condition,
339        unpredictable results occurred, instead of the error return
340        PCRE_ERROR_DFA_UITEM.
341    
342    5.  The C++ GlobalReplace function was not working like Perl for the special
343        situation when an empty string is matched. It now does the fancy magic
344        stuff that is necessary.
345    
346    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
347        removed. (These were left over from very, very early versions of PCRE.)
348    
349    7.  Some cosmetic changes to the code to make life easier when compiling it
350        as part of something else:
351    
352        (a) Change DEBUG to PCRE_DEBUG.
353    
354        (b) In pcre_compile(), rename the member of the "branch_chain" structure
355            called "current" as "current_branch", to prevent a collision with the
356            Linux macro when compiled as a kernel module.
357    
358        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
359            prevent a collision with the Linux macro when compiled as a kernel
360            module.
361    
362    8.  In pcre_compile() there are some checks for integer overflows that used to
363        cast potentially large values to (double). This has been changed to that
364        when building, a check for int64_t is made, and if it is found, it is used
365        instead, thus avoiding the use of floating point arithmetic. (There is no
366        other use of FP in PCRE.) If int64_t is not found, the fallback is to
367        double.
368    
369    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
370        2005 (difference between two addresses compared to an unsigned value).
371    
372    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
373        custom one, because of the following reported problem in Windows:
374    
375          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
376              under Win32.
377          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
378              therefore missing the function definition.
379          - The compiler thus generates a "C" signature for the test function.
380          - The linker fails to find the "C" function.
381          - PCRE fails to configure if asked to do so against libbz2.
382    
383    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
384        messages were output:
385    
386          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
387          rerunning libtoolize, to keep the correct libtool macros in-tree.
388          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
389    
390        I have done both of these things.
391    
392    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
393        most of the time, it *can* run out if it is given a pattern that contains a
394        runaway infinite recursion. I updated the discussion in the pcrestack man
395        page.
396    
397    13. Now that we have gone to the x.xx style of version numbers, the minor
398        version may start with zero. Using 08 or 09 is a bad idea because users
399        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
400        interpreted as invalid octal numbers. I've updated the previous comment in
401        configure.ac, and also added a check that gives an error if 08 or 09 are
402        used.
403    
404    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
405        causing partial matching to fail when the end of the subject matched \W
406        in a UTF-8 pattern where \W was quantified with a minimum of 3.
407    
408    15. There were some discrepancies between the declarations in pcre_internal.h
409        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
410        their definitions. The declarations used "const uschar *" and the
411        definitions used USPTR. Even though USPTR is normally defined as "const
412        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
413        reported that: "This difference in casting confuses some C++ compilers, for
414        example, SunCC recognizes above declarations as different functions and
415        generates broken code for hbpcre." I have changed the declarations to use
416        USPTR.
417    
418    16. GNU libtool is named differently on some systems. The autogen.sh script now
419        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
420        (FreeBSD).
421    
422    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
423        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
424        comment: "Figure out how to create a longlong from a string: strtoll and
425        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
426        instance, but it only takes 2 args instead of 3!"
427    
428    18. A subtle bug concerned with back references has been fixed by a change of
429        specification, with a corresponding code fix. A pattern such as
430        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
431        refers, was giving matches when it shouldn't. For example, xa=xaaa would
432        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
433        same bug. Such groups have to be quantified to be useful, or contained
434        inside another quantified group. (If there's no repetition, the reference
435        can never match.) The problem arises because, having left the group and
436        moved on to the rest of the pattern, a later failure that backtracks into
437        the group uses the captured value from the final iteration of the group
438        rather than the correct earlier one. I have fixed this in PCRE by forcing
439        any group that contains a reference to itself to be an atomic group; that
440        is, there cannot be any backtracking into it once it has completed. This is
441        similar to recursive and subroutine calls.
442    
443    
444    Version 8.00 19-Oct-09
445  ----------------------  ----------------------
446    
447  1.  The table for translating pcre_compile() error codes into POSIX error codes  1.  The table for translating pcre_compile() error codes into POSIX error codes
448      was out-of-date, and there was no check on the pcre_compile() error code      was out-of-date, and there was no check on the pcre_compile() error code
449      being within the table. This could lead to an OK return being given in      being within the table. This could lead to an OK return being given in
450      error.      error.
451    
452    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
453        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
454        in a Windows environment.
455    
456    3.  The pcregrep --count option prints the count for each file even when it is
457        zero, as does GNU grep. However, pcregrep was also printing all files when
458        --files-with-matches was added. Now, when both options are given, it prints
459        counts only for those files that have at least one match. (GNU grep just
460        prints the file name in this circumstance, but including the count seems
461        more useful - otherwise, why use --count?) Also ensured that the
462        combination -clh just lists non-zero counts, with no names.
463    
464    4.  The long form of the pcregrep -F option was incorrectly implemented as
465        --fixed_strings instead of --fixed-strings. This is an incompatible change,
466        but it seems right to fix it, and I didn't think it was worth preserving
467        the old behaviour.
468    
469    5.  The command line items --regex=pattern and --regexp=pattern were not
470        recognized by pcregrep, which required --regex pattern or --regexp pattern
471        (with a space rather than an '='). The man page documented the '=' forms,
472        which are compatible with GNU grep; these now work.
473    
474    6.  No libpcreposix.pc file was created for pkg-config; there was just
475        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
476    
477    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
478        when UCP support is not needed, by modifying the Python script that
479        generates it from Unicode data files. This should not matter if the module
480        is correctly used as a library, but I received one complaint about 50K of
481        unwanted data. My guess is that the person linked everything into his
482        program rather than using a library. Anyway, it does no harm.
483    
484    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
485        was a minimum greater than 1 for a wide character in a possessive
486        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
487        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
488        character. Chaos in the form of incorrect output or a compiling loop could
489        result.
490    
491    9.  The restrictions on what a pattern can contain when partial matching is
492        requested for pcre_exec() have been removed. All patterns can now be
493        partially matched by this function. In addition, if there are at least two
494        slots in the offset vector, the offset of the earliest inspected character
495        for the match and the offset of the end of the subject are set in them when
496        PCRE_ERROR_PARTIAL is returned.
497    
498    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
499        synonymous with PCRE_PARTIAL, for backwards compatibility, and
500        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
501        and may be more useful for multi-segment matching.
502    
503    11. Partial matching with pcre_exec() is now more intuitive. A partial match
504        used to be given if ever the end of the subject was reached; now it is
505        given only if matching could not proceed because another character was
506        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
507        string "Z", which now yields "no match" instead of "partial match". In the
508        case of pcre_dfa_exec(), "no match" is given if every matching path for the
509        final character ended with (*FAIL).
510    
511    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
512        if the pattern had a "must contain" character that was already found in the
513        earlier partial match, unless partial matching was again requested. For
514        example, with the pattern /dog.(body)?/, the "must contain" character is
515        "g". If the first part-match was for the string "dog", restarting with
516        "sbody" failed. This bug has been fixed.
517    
518    13. The string returned by pcre_dfa_exec() after a partial match has been
519        changed so that it starts at the first inspected character rather than the
520        first character of the match. This makes a difference only if the pattern
521        starts with a lookbehind assertion or \b or \B (\K is not supported by
522        pcre_dfa_exec()). It's an incompatible change, but it makes the two
523        matching functions compatible, and I think it's the right thing to do.
524    
525    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
526        so that the demonstration program is easily available in environments where
527        PCRE has not been installed from source.
528    
529    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
530        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
531        library.
532    
533    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
534        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
535        is not the first non-POSIX option to be added. Clearly some people find
536        these options useful.
537    
538    17. If a caller to the POSIX matching function regexec() passes a non-zero
539        value for nmatch with a NULL value for pmatch, the value of
540        nmatch is forced to zero.
541    
542    18. RunGrepTest did not have a test for the availability of the -u option of
543        the diff command, as RunTest does. It now checks in the same way as
544        RunTest, and also checks for the -b option.
545    
546    19. If an odd number of negated classes containing just a single character
547        interposed, within parentheses, between a forward reference to a named
548        subpattern and the definition of the subpattern, compilation crashed with
549        an internal error, complaining that it could not find the referenced
550        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
551        [The bug was that it was starting one character too far in when skipping
552        over the character class, thus treating the ] as data rather than
553        terminating the class. This meant it could skip too much.]
554    
555    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
556        /g option in pcretest when the pattern contains \K, which makes it possible
557        to have an empty string match not at the start, even when the pattern is
558        anchored. Updated pcretest and pcredemo to use this option.
559    
560    21. If the maximum number of capturing subpatterns in a recursion was greater
561        than the maximum at the outer level, the higher number was returned, but
562        with unset values at the outer level. The correct (outer level) value is
563        now given.
564    
565    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
566        PCRE did not set those parentheses (unlike Perl). I have now found a way to
567        make it do so. The string so far is captured, making this feature
568        compatible with Perl.
569    
570    23. The tests have been re-organized, adding tests 11 and 12, to make it
571        possible to check the Perl 5.10 features against Perl 5.10.
572    
573    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
574        pattern matches a fixed length string. PCRE did not allow this; now it
575        does. Neither allows recursion.
576    
577    25. I finally figured out how to implement a request to provide the minimum
578        length of subject string that was needed in order to match a given pattern.
579        (It was back references and recursion that I had previously got hung up
580        on.) This code has now been added to pcre_study(); it finds a lower bound
581        to the length of subject needed. It is not necessarily the greatest lower
582        bound, but using it to avoid searching strings that are too short does give
583        some useful speed-ups. The value is available to calling programs via
584        pcre_fullinfo().
585    
586    26. While implementing 25, I discovered to my embarrassment that pcretest had
587        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
588        study optimizations had never been tested with that matching function.
589        Oops. What is worse, even when it was passed study data, there was a bug in
590        pcre_dfa_exec() that meant it never actually used it. Double oops. There
591        were also very few tests of studied patterns with pcre_dfa_exec().
592    
593    27. If (?| is used to create subpatterns with duplicate numbers, they are now
594        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
595        on the other side of the coin, they are no longer allowed to have different
596        names, because these cannot be distinguished in PCRE, and this has caused
597        confusion. (This is a difference from Perl.)
598    
599    28. When duplicate subpattern names are present (necessarily with different
600        numbers, as required by 27 above), and a test is made by name in a
601        conditional pattern, either for a subpattern having been matched, or for
602        recursion in such a pattern, all the associated numbered subpatterns are
603        tested, and the overall condition is true if the condition is true for any
604        one of them. This is the way Perl works, and is also more like the way
605        testing by number works.
606    
607    
608  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
609  ---------------------  ---------------------

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