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revision 419 by ph10, Wed Aug 12 10:45:33 2009 UTC revision 476 by ph10, Sun Jan 3 15:37:24 2010 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.00 ??-???-??  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
30    5.  The C++ GlobalReplace function was not working like Perl for the special
31        situation when an empty string is matched. It now does the fancy magic
32        stuff that is necessary.
34    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
35        removed. (These were left over from very, very early versions of PCRE.)
37    7.  Some cosmetic changes to the code to make life easier when compiling it
38        as part of something else:
40        (a) Change DEBUG to PCRE_DEBUG.
42        (b) In pcre_compile(), rename the member of the "branch_chain" structure
43            called "current" as "current_branch", to prevent a collision with the
44            Linux macro when compiled as a kernel module.
46        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
47            prevent a collision with the Linux macro when compiled as a kernel
48            module.
50    8.  In pcre_compile() there are some checks for integer overflows that used to
51        cast potentially large values to (double). This has been changed to that
52        when building, a check for int64_t is made, and if it is found, it is used
53        instead, thus avoiding the use of floating point arithmetic. (There is no
54        other use of FP in PCRE.) If int64_t is not found, the fallback is to
55        double.
57    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
58        2005 (difference between two addresses compared to an unsigned value).
62    Version 8.00 19-Oct-09
63  ----------------------  ----------------------
65  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
66      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
67      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
68      error.      error.
70  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
71      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
72      in a Windows environment.      in a Windows environment.
74    3.  The pcregrep --count option prints the count for each file even when it is
75        zero, as does GNU grep. However, pcregrep was also printing all files when
76        --files-with-matches was added. Now, when both options are given, it prints
77        counts only for those files that have at least one match. (GNU grep just
78        prints the file name in this circumstance, but including the count seems
79        more useful - otherwise, why use --count?) Also ensured that the
80        combination -clh just lists non-zero counts, with no names.
82    4.  The long form of the pcregrep -F option was incorrectly implemented as
83        --fixed_strings instead of --fixed-strings. This is an incompatible change,
84        but it seems right to fix it, and I didn't think it was worth preserving
85        the old behaviour.
87    5.  The command line items --regex=pattern and --regexp=pattern were not
88        recognized by pcregrep, which required --regex pattern or --regexp pattern
89        (with a space rather than an '='). The man page documented the '=' forms,
90        which are compatible with GNU grep; these now work.
92    6.  No libpcreposix.pc file was created for pkg-config; there was just
93        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
95    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
96        when UCP support is not needed, by modifying the Python script that
97        generates it from Unicode data files. This should not matter if the module
98        is correctly used as a library, but I received one complaint about 50K of
99        unwanted data. My guess is that the person linked everything into his
100        program rather than using a library. Anyway, it does no harm.
102    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
103        was a minimum greater than 1 for a wide character in a possessive
104        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
105        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
106        character. Chaos in the form of incorrect output or a compiling loop could
107        result.
109    9.  The restrictions on what a pattern can contain when partial matching is
110        requested for pcre_exec() have been removed. All patterns can now be
111        partially matched by this function. In addition, if there are at least two
112        slots in the offset vector, the offset of the earliest inspected character
113        for the match and the offset of the end of the subject are set in them when
114        PCRE_ERROR_PARTIAL is returned.
116    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
117        synonymous with PCRE_PARTIAL, for backwards compatibility, and
118        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
119        and may be more useful for multi-segment matching.
121    11. Partial matching with pcre_exec() is now more intuitive. A partial match
122        used to be given if ever the end of the subject was reached; now it is
123        given only if matching could not proceed because another character was
124        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
125        string "Z", which now yields "no match" instead of "partial match". In the
126        case of pcre_dfa_exec(), "no match" is given if every matching path for the
127        final character ended with (*FAIL).
129    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
130        if the pattern had a "must contain" character that was already found in the
131        earlier partial match, unless partial matching was again requested. For
132        example, with the pattern /dog.(body)?/, the "must contain" character is
133        "g". If the first part-match was for the string "dog", restarting with
134        "sbody" failed. This bug has been fixed.
136    13. The string returned by pcre_dfa_exec() after a partial match has been
137        changed so that it starts at the first inspected character rather than the
138        first character of the match. This makes a difference only if the pattern
139        starts with a lookbehind assertion or \b or \B (\K is not supported by
140        pcre_dfa_exec()). It's an incompatible change, but it makes the two
141        matching functions compatible, and I think it's the right thing to do.
143    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
144        so that the demonstration program is easily available in environments where
145        PCRE has not been installed from source.
147    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
148        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
149        library.
151    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
152        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
153        is not the first non-POSIX option to be added. Clearly some people find
154        these options useful.
156    17. If a caller to the POSIX matching function regexec() passes a non-zero
157        value for nmatch with a NULL value for pmatch, the value of
158        nmatch is forced to zero.
160    18. RunGrepTest did not have a test for the availability of the -u option of
161        the diff command, as RunTest does. It now checks in the same way as
162        RunTest, and also checks for the -b option.
164    19. If an odd number of negated classes containing just a single character
165        interposed, within parentheses, between a forward reference to a named
166        subpattern and the definition of the subpattern, compilation crashed with
167        an internal error, complaining that it could not find the referenced
168        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
169        [The bug was that it was starting one character too far in when skipping
170        over the character class, thus treating the ] as data rather than
171        terminating the class. This meant it could skip too much.]
173    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
174        /g option in pcretest when the pattern contains \K, which makes it possible
175        to have an empty string match not at the start, even when the pattern is
176        anchored. Updated pcretest and pcredemo to use this option.
178    21. If the maximum number of capturing subpatterns in a recursion was greater
179        than the maximum at the outer level, the higher number was returned, but
180        with unset values at the outer level. The correct (outer level) value is
181        now given.
183    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
184        PCRE did not set those parentheses (unlike Perl). I have now found a way to
185        make it do so. The string so far is captured, making this feature
186        compatible with Perl.
188    23. The tests have been re-organized, adding tests 11 and 12, to make it
189        possible to check the Perl 5.10 features against Perl 5.10.
191    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
192        pattern matches a fixed length string. PCRE did not allow this; now it
193        does. Neither allows recursion.
195    25. I finally figured out how to implement a request to provide the minimum
196        length of subject string that was needed in order to match a given pattern.
197        (It was back references and recursion that I had previously got hung up
198        on.) This code has now been added to pcre_study(); it finds a lower bound
199        to the length of subject needed. It is not necessarily the greatest lower
200        bound, but using it to avoid searching strings that are too short does give
201        some useful speed-ups. The value is available to calling programs via
202        pcre_fullinfo().
204    26. While implementing 25, I discovered to my embarrassment that pcretest had
205        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
206        study optimizations had never been tested with that matching function.
207        Oops. What is worse, even when it was passed study data, there was a bug in
208        pcre_dfa_exec() that meant it never actually used it. Double oops. There
209        were also very few tests of studied patterns with pcre_dfa_exec().
211    27. If (?| is used to create subpatterns with duplicate numbers, they are now
212        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
213        on the other side of the coin, they are no longer allowed to have different
214        names, because these cannot be distinguished in PCRE, and this has caused
215        confusion. (This is a difference from Perl.)
217    28. When duplicate subpattern names are present (necessarily with different
218        numbers, as required by 27 above), and a test is made by name in a
219        conditional pattern, either for a subpattern having been matched, or for
220        recursion in such a pattern, all the associated numbered subpatterns are
221        tested, and the overall condition is true if the condition is true for any
222        one of them. This is the way Perl works, and is also more like the way
223        testing by number works.
226  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09

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