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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 8.01 11-Dec-09
5    ----------------------
7    1.  If a pattern contained a conditional subpattern with only one branch (in
8        particular, this includes all (DEFINE) patterns), a call to pcre_study()
9        computed the wrong minimum data length (which is of course zero for such
10        subpatterns).
12    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
13        the pattern is reset in the first branch, pcre_compile() failed with
14        "internal error: code overflow at offset...". This happened only when
15        the reset was to the original external option setting. (An optimization
16        abstracts leading options settings into an external setting, which was the
17        cause of this.)
19    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
20        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
21        assertion pattern did not match (meaning that the assertion was true), it
22        was incorrectly treated as false if the SKIP had been reached during the
23        matching. This also applied to assertions used as conditions.
25    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
26        assertion subpattern, including such a pattern used as a condition,
27        unpredictable results occurred, instead of the error return
31    Version 8.00 19-Oct-09
32    ----------------------
34    1.  The table for translating pcre_compile() error codes into POSIX error codes
35        was out-of-date, and there was no check on the pcre_compile() error code
36        being within the table. This could lead to an OK return being given in
37        error.
39    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
40        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
41        in a Windows environment.
43    3.  The pcregrep --count option prints the count for each file even when it is
44        zero, as does GNU grep. However, pcregrep was also printing all files when
45        --files-with-matches was added. Now, when both options are given, it prints
46        counts only for those files that have at least one match. (GNU grep just
47        prints the file name in this circumstance, but including the count seems
48        more useful - otherwise, why use --count?) Also ensured that the
49        combination -clh just lists non-zero counts, with no names.
51    4.  The long form of the pcregrep -F option was incorrectly implemented as
52        --fixed_strings instead of --fixed-strings. This is an incompatible change,
53        but it seems right to fix it, and I didn't think it was worth preserving
54        the old behaviour.
56    5.  The command line items --regex=pattern and --regexp=pattern were not
57        recognized by pcregrep, which required --regex pattern or --regexp pattern
58        (with a space rather than an '='). The man page documented the '=' forms,
59        which are compatible with GNU grep; these now work.
61    6.  No libpcreposix.pc file was created for pkg-config; there was just
62        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
64    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
65        when UCP support is not needed, by modifying the Python script that
66        generates it from Unicode data files. This should not matter if the module
67        is correctly used as a library, but I received one complaint about 50K of
68        unwanted data. My guess is that the person linked everything into his
69        program rather than using a library. Anyway, it does no harm.
71    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
72        was a minimum greater than 1 for a wide character in a possessive
73        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
74        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
75        character. Chaos in the form of incorrect output or a compiling loop could
76        result.
78    9.  The restrictions on what a pattern can contain when partial matching is
79        requested for pcre_exec() have been removed. All patterns can now be
80        partially matched by this function. In addition, if there are at least two
81        slots in the offset vector, the offset of the earliest inspected character
82        for the match and the offset of the end of the subject are set in them when
83        PCRE_ERROR_PARTIAL is returned.
85    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
86        synonymous with PCRE_PARTIAL, for backwards compatibility, and
87        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
88        and may be more useful for multi-segment matching.
90    11. Partial matching with pcre_exec() is now more intuitive. A partial match
91        used to be given if ever the end of the subject was reached; now it is
92        given only if matching could not proceed because another character was
93        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
94        string "Z", which now yields "no match" instead of "partial match". In the
95        case of pcre_dfa_exec(), "no match" is given if every matching path for the
96        final character ended with (*FAIL).
98    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
99        if the pattern had a "must contain" character that was already found in the
100        earlier partial match, unless partial matching was again requested. For
101        example, with the pattern /dog.(body)?/, the "must contain" character is
102        "g". If the first part-match was for the string "dog", restarting with
103        "sbody" failed. This bug has been fixed.
105    13. The string returned by pcre_dfa_exec() after a partial match has been
106        changed so that it starts at the first inspected character rather than the
107        first character of the match. This makes a difference only if the pattern
108        starts with a lookbehind assertion or \b or \B (\K is not supported by
109        pcre_dfa_exec()). It's an incompatible change, but it makes the two
110        matching functions compatible, and I think it's the right thing to do.
112    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
113        so that the demonstration program is easily available in environments where
114        PCRE has not been installed from source.
116    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
117        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
118        library.
120    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
121        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
122        is not the first non-POSIX option to be added. Clearly some people find
123        these options useful.
125    17. If a caller to the POSIX matching function regexec() passes a non-zero
126        value for nmatch with a NULL value for pmatch, the value of
127        nmatch is forced to zero.
129    18. RunGrepTest did not have a test for the availability of the -u option of
130        the diff command, as RunTest does. It now checks in the same way as
131        RunTest, and also checks for the -b option.
133    19. If an odd number of negated classes containing just a single character
134        interposed, within parentheses, between a forward reference to a named
135        subpattern and the definition of the subpattern, compilation crashed with
136        an internal error, complaining that it could not find the referenced
137        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
138        [The bug was that it was starting one character too far in when skipping
139        over the character class, thus treating the ] as data rather than
140        terminating the class. This meant it could skip too much.]
142    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
143        /g option in pcretest when the pattern contains \K, which makes it possible
144        to have an empty string match not at the start, even when the pattern is
145        anchored. Updated pcretest and pcredemo to use this option.
147    21. If the maximum number of capturing subpatterns in a recursion was greater
148        than the maximum at the outer level, the higher number was returned, but
149        with unset values at the outer level. The correct (outer level) value is
150        now given.
152    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
153        PCRE did not set those parentheses (unlike Perl). I have now found a way to
154        make it do so. The string so far is captured, making this feature
155        compatible with Perl.
157    23. The tests have been re-organized, adding tests 11 and 12, to make it
158        possible to check the Perl 5.10 features against Perl 5.10.
160    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
161        pattern matches a fixed length string. PCRE did not allow this; now it
162        does. Neither allows recursion.
164    25. I finally figured out how to implement a request to provide the minimum
165        length of subject string that was needed in order to match a given pattern.
166        (It was back references and recursion that I had previously got hung up
167        on.) This code has now been added to pcre_study(); it finds a lower bound
168        to the length of subject needed. It is not necessarily the greatest lower
169        bound, but using it to avoid searching strings that are too short does give
170        some useful speed-ups. The value is available to calling programs via
171        pcre_fullinfo().
173    26. While implementing 25, I discovered to my embarrassment that pcretest had
174        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
175        study optimizations had never been tested with that matching function.
176        Oops. What is worse, even when it was passed study data, there was a bug in
177        pcre_dfa_exec() that meant it never actually used it. Double oops. There
178        were also very few tests of studied patterns with pcre_dfa_exec().
180    27. If (?| is used to create subpatterns with duplicate numbers, they are now
181        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
182        on the other side of the coin, they are no longer allowed to have different
183        names, because these cannot be distinguished in PCRE, and this has caused
184        confusion. (This is a difference from Perl.)
186    28. When duplicate subpattern names are present (necessarily with different
187        numbers, as required by 27 above), and a test is made by name in a
188        conditional pattern, either for a subpattern having been matched, or for
189        recursion in such a pattern, all the associated numbered subpatterns are
190        tested, and the overall condition is true if the condition is true for any
191        one of them. This is the way Perl works, and is also more like the way
192        testing by number works.
195  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
196  ---------------------  ---------------------

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