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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 8.01 11-Dec-09
5    ----------------------
6    
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).
11    
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.)
18    
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.
24    
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
28        PCRE_ERROR_DFA_UITEM.
29    
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.
33    
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.)
36    
37    7.  Some cosmetic changes to the code to make life easier when compiling it
38        as part of something else:
39    
40        (a) Change DEBUG to PCRE_DEBUG.
41    
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.
45    
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.
49    
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.
56    
57    
58    
59    Version 8.00 19-Oct-09
60    ----------------------
61    
62    1.  The table for translating pcre_compile() error codes into POSIX error codes
63        was out-of-date, and there was no check on the pcre_compile() error code
64        being within the table. This could lead to an OK return being given in
65        error.
66    
67    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
68        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
69        in a Windows environment.
70    
71    3.  The pcregrep --count option prints the count for each file even when it is
72        zero, as does GNU grep. However, pcregrep was also printing all files when
73        --files-with-matches was added. Now, when both options are given, it prints
74        counts only for those files that have at least one match. (GNU grep just
75        prints the file name in this circumstance, but including the count seems
76        more useful - otherwise, why use --count?) Also ensured that the
77        combination -clh just lists non-zero counts, with no names.
78    
79    4.  The long form of the pcregrep -F option was incorrectly implemented as
80        --fixed_strings instead of --fixed-strings. This is an incompatible change,
81        but it seems right to fix it, and I didn't think it was worth preserving
82        the old behaviour.
83    
84    5.  The command line items --regex=pattern and --regexp=pattern were not
85        recognized by pcregrep, which required --regex pattern or --regexp pattern
86        (with a space rather than an '='). The man page documented the '=' forms,
87        which are compatible with GNU grep; these now work.
88    
89    6.  No libpcreposix.pc file was created for pkg-config; there was just
90        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
91    
92    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
93        when UCP support is not needed, by modifying the Python script that
94        generates it from Unicode data files. This should not matter if the module
95        is correctly used as a library, but I received one complaint about 50K of
96        unwanted data. My guess is that the person linked everything into his
97        program rather than using a library. Anyway, it does no harm.
98    
99    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
100        was a minimum greater than 1 for a wide character in a possessive
101        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
102        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
103        character. Chaos in the form of incorrect output or a compiling loop could
104        result.
105    
106    9.  The restrictions on what a pattern can contain when partial matching is
107        requested for pcre_exec() have been removed. All patterns can now be
108        partially matched by this function. In addition, if there are at least two
109        slots in the offset vector, the offset of the earliest inspected character
110        for the match and the offset of the end of the subject are set in them when
111        PCRE_ERROR_PARTIAL is returned.
112    
113    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
114        synonymous with PCRE_PARTIAL, for backwards compatibility, and
115        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
116        and may be more useful for multi-segment matching.
117    
118    11. Partial matching with pcre_exec() is now more intuitive. A partial match
119        used to be given if ever the end of the subject was reached; now it is
120        given only if matching could not proceed because another character was
121        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
122        string "Z", which now yields "no match" instead of "partial match". In the
123        case of pcre_dfa_exec(), "no match" is given if every matching path for the
124        final character ended with (*FAIL).
125    
126    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
127        if the pattern had a "must contain" character that was already found in the
128        earlier partial match, unless partial matching was again requested. For
129        example, with the pattern /dog.(body)?/, the "must contain" character is
130        "g". If the first part-match was for the string "dog", restarting with
131        "sbody" failed. This bug has been fixed.
132    
133    13. The string returned by pcre_dfa_exec() after a partial match has been
134        changed so that it starts at the first inspected character rather than the
135        first character of the match. This makes a difference only if the pattern
136        starts with a lookbehind assertion or \b or \B (\K is not supported by
137        pcre_dfa_exec()). It's an incompatible change, but it makes the two
138        matching functions compatible, and I think it's the right thing to do.
139    
140    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
141        so that the demonstration program is easily available in environments where
142        PCRE has not been installed from source.
143    
144    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
145        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
146        library.
147    
148    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
149        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
150        is not the first non-POSIX option to be added. Clearly some people find
151        these options useful.
152    
153    17. If a caller to the POSIX matching function regexec() passes a non-zero
154        value for nmatch with a NULL value for pmatch, the value of
155        nmatch is forced to zero.
156    
157    18. RunGrepTest did not have a test for the availability of the -u option of
158        the diff command, as RunTest does. It now checks in the same way as
159        RunTest, and also checks for the -b option.
160    
161    19. If an odd number of negated classes containing just a single character
162        interposed, within parentheses, between a forward reference to a named
163        subpattern and the definition of the subpattern, compilation crashed with
164        an internal error, complaining that it could not find the referenced
165        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
166        [The bug was that it was starting one character too far in when skipping
167        over the character class, thus treating the ] as data rather than
168        terminating the class. This meant it could skip too much.]
169    
170    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
171        /g option in pcretest when the pattern contains \K, which makes it possible
172        to have an empty string match not at the start, even when the pattern is
173        anchored. Updated pcretest and pcredemo to use this option.
174    
175    21. If the maximum number of capturing subpatterns in a recursion was greater
176        than the maximum at the outer level, the higher number was returned, but
177        with unset values at the outer level. The correct (outer level) value is
178        now given.
179    
180    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
181        PCRE did not set those parentheses (unlike Perl). I have now found a way to
182        make it do so. The string so far is captured, making this feature
183        compatible with Perl.
184    
185    23. The tests have been re-organized, adding tests 11 and 12, to make it
186        possible to check the Perl 5.10 features against Perl 5.10.
187    
188    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
189        pattern matches a fixed length string. PCRE did not allow this; now it
190        does. Neither allows recursion.
191    
192    25. I finally figured out how to implement a request to provide the minimum
193        length of subject string that was needed in order to match a given pattern.
194        (It was back references and recursion that I had previously got hung up
195        on.) This code has now been added to pcre_study(); it finds a lower bound
196        to the length of subject needed. It is not necessarily the greatest lower
197        bound, but using it to avoid searching strings that are too short does give
198        some useful speed-ups. The value is available to calling programs via
199        pcre_fullinfo().
200    
201    26. While implementing 25, I discovered to my embarrassment that pcretest had
202        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
203        study optimizations had never been tested with that matching function.
204        Oops. What is worse, even when it was passed study data, there was a bug in
205        pcre_dfa_exec() that meant it never actually used it. Double oops. There
206        were also very few tests of studied patterns with pcre_dfa_exec().
207    
208    27. If (?| is used to create subpatterns with duplicate numbers, they are now
209        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
210        on the other side of the coin, they are no longer allowed to have different
211        names, because these cannot be distinguished in PCRE, and this has caused
212        confusion. (This is a difference from Perl.)
213    
214    28. When duplicate subpattern names are present (necessarily with different
215        numbers, as required by 27 above), and a test is made by name in a
216        conditional pattern, either for a subpattern having been matched, or for
217        recursion in such a pattern, all the associated numbered subpatterns are
218        tested, and the overall condition is true if the condition is true for any
219        one of them. This is the way Perl works, and is also more like the way
220        testing by number works.
221    
222    
223  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
224  ---------------------  ---------------------
225    

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