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revision 661 by ph10, Sun Aug 21 09:00:54 2011 UTC revision 771 by ph10, Tue Nov 29 15:34:12 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.20  Version 8.21
5  ------------  ------------
7  1. Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had  1.  Updating the JIT compiler.
8  a POSIX class. After further experiments with Perl, which convinced me that  
9  Perl has bugs and confusions, a closing square bracket is no longer allowed in  2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10  a POSIX name.      are added as well.
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14        calling _pcre_jit_exec. Some extra comments are added.
16    4.  Mark settings inside atomic groups that do not contain any capturing
17        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18        was introduced by change 18 for 8.20.
20    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
23    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25        This bug was probably introduced by change 9 of 8.13.
27    7.  While fixing 6 above, I noticed that a number of other items were being
28        incorrectly rejected as "not fixed length". This arose partly because newer
29        opcodes had not been added to the fixed-length checking code. I have (a)
30        corrected the bug and added tests for these items, and (b) arranged for an
31        error to occur if an unknown opcode is encountered while checking for fixed
32        length instead of just assuming "not fixed length". The items that were
33        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
37    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38        being incorrectly compiled and would have given unpredicatble results.
40    9.  A possessively repeated subpattern with minimum repeat count greater than
41        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43        the first (A) could occur when it should not.
45    10. Add a cast and remove a redundant test from the code.
47    11. JIT should use pcre_malloc/pcre_free for allocation.
49    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
50        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
51        is anything other than /usr, -L is still shown).
53    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
55    14. Perl does not support \N without a following name in a [] class; PCRE now
56        also gives an error.
58    15. If a forward reference was repeated with an upper limit of around 2000,
59        it caused the error "internal error: overran compiling workspace". This
60        is now checked, and causes "too many forward references" instead.
62    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
63        incorrectly expecting the subject to contain another "a" after the start.
65    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
66        in the match, the SKIP should be ignored. This was not happening; instead
67        the SKIP was being treated as NOMATCH. For patterns such as
68        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
69        tested.
71    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
72        now much more compatible with Perl, in particular in cases where the result
73        is a non-match for a non-anchored pattern. For example, if
74        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
75        "m", where previously it did not return a name. A side effect of this
76        change is that for partial matches, the last encountered mark name is
77        returned, as for non matches. A number of tests that were previously not
78        Perl-compatible have been moved into the Perl-compatible test files. The
79        refactoring has had the pleasing side effect of removing one argument from
80        the match() function, thus reducing its stack requirements.
83    Version 8.20 21-Oct-2011
84    ------------------------
86    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
87        a POSIX class. After further experiments with Perl, which convinced me that
88        Perl has bugs and confusions, a closing square bracket is no longer allowed
89        in a POSIX name. This bug also affected patterns with classes that started
90        with full stops.
92    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
93        captured substring, but while checking the failing first alternative,
94        substring 1 is temporarily captured. If the output vector supplied to
95        pcre_exec() was not big enough for this capture, the yield of the function
96        was still zero ("insufficient space for captured substrings"). This cannot
97        be totally fixed without adding another stack variable, which seems a lot
98        of expense for a edge case. However, I have improved the situation in cases
99        such as /(a)(b)x|abc/ matched against "abc", where the return code
100        indicates that fewer than the maximum number of slots in the ovector have
101        been set.
103    3.  Related to (2) above: when there are more back references in a pattern than
104        slots in the output vector, pcre_exec() uses temporary memory during
105        matching, and copies in the captures as far as possible afterwards. It was
106        using the entire output vector, but this conflicts with the specification
107        that only 2/3 is used for passing back captured substrings. Now it uses
108        only the first 2/3, for compatibility. This is, of course, another edge
109        case.
111    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
112        main code base, and can be used by building with --enable-jit. When this is
113        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
114        runtime --no-jit option is given.
116    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
117        ovector, the return from the function was zero, implying that there were
118        other matches that did not fit. The correct "exactly full" value is now
119        returned.
121    6.  If a subpattern that was called recursively or as a subroutine contained
122        (*PRUNE) or any other control that caused it to give a non-standard return,
123        invalid errors such as "Error -26 (nested recursion at the same subject
124        position)" or even infinite loops could occur.
126    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
127        computing the minimum length on reaching *ACCEPT, and so ended up with the
128        wrong value of 1 rather than 0. Further investigation indicates that
129        computing a minimum subject length in the presence of *ACCEPT is difficult
130        (think back references, subroutine calls), and so I have changed the code
131        so that no minimum is registered for a pattern that contains *ACCEPT.
133    8.  If (*THEN) was present in the first (true) branch of a conditional group,
134        it was not handled as intended. [But see 16 below.]
136    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
137        Sheri Pierce.
139    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
140        the first byte in a match must be "a".
142    11. Change 17 for 8.13 increased the recursion depth for patterns like
143        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
144        pattern contains any instances of (*THEN). If it does not, the old
145        optimizations are restored. It would be nice to do this on a per-group
146        basis, but at the moment that is not feasible.
148    12. In some environments, the output of pcretest -C is CRLF terminated. This
149        broke RunTest's code that checks for the link size. A single white space
150        character after the value is now allowed for.
152    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
153        For "fr", it uses the Windows-specific input and output files.
155    14. If (*THEN) appeared in a group that was called recursively or as a
156        subroutine, it did not work as intended. [But see next item.]
158    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
159        pattern fragments (but not containing any | characters). If A and B are
160        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
161        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
162        D. In other words, Perl considers parentheses that do not contain any |
163        characters to be part of a surrounding alternative, whereas PCRE was
164        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
165        differently. PCRE now behaves in the same way as Perl, except in the case
166        of subroutine/recursion calls such as (?1) which have in any case always
167        been different (but PCRE had them first :-).
169    16. Related to 15 above: Perl does not treat the | in a conditional group as
170        creating alternatives. Such a group is treated in the same way as an
171        ordinary group without any | characters when processing (*THEN). PCRE has
172        been changed to match Perl's behaviour.
174    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
175        RunGrepTest script failed.
177    18. Change 22 for version 13 caused atomic groups to use more stack. This is
178        inevitable for groups that contain captures, but it can lead to a lot of
179        stack use in large patterns. The old behaviour has been restored for atomic
180        groups that do not contain any capturing parentheses.
182    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
183        suppress the check for a minimum subject length at run time. (If it was
184        given to pcre_exec() or pcre_dfa_exec() it did work.)
186    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
187        fail to work when decoding hex characters in data strings in EBCDIC
188        environments.
190    21. It appears that in at least one Mac OS environment, the isxdigit() function
191        is implemented as a macro that evaluates to its argument more than once,
192        contravening the C 90 Standard (I haven't checked a later standard). There
193        was an instance in pcretest which caused it to go wrong when processing
194        \x{...} escapes in subject strings. The has been rewritten to avoid using
195        things like p++ in the argument of isxdigit().
198  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 107  Version 8.13 16-Aug-2011 Line 292  Version 8.13 16-Aug-2011
292      tail recursion to cut down on stack usage. Unfortunately, now that there is      tail recursion to cut down on stack usage. Unfortunately, now that there is
293      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
294      no longer possible because the return has to be checked for (*THEN). These      no longer possible because the return has to be checked for (*THEN). These
295      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
297  18. If a pattern containing \R was studied, it was assumed that \R always  18. If a pattern containing \R was studied, it was assumed that \R always
298      matched two bytes, thus causing the minimum subject length to be      matched two bytes, thus causing the minimum subject length to be

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