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revision 681 by ph10, Tue Sep 6 09:16:32 2011 UTC revision 738 by ph10, Fri Oct 21 09:04:01 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.20  Version 8.20 21-Oct-2011
5  ------------  ------------------------
6    
7    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
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
10        in a POSIX name. This bug also affected patterns with classes that started
11        with full stops.
12    
13    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
14        captured substring, but while checking the failing first alternative,
15        substring 1 is temporarily captured. If the output vector supplied to
16        pcre_exec() was not big enough for this capture, the yield of the function
17        was still zero ("insufficient space for captured substrings"). This cannot
18        be totally fixed without adding another stack variable, which seems a lot
19        of expense for a edge case. However, I have improved the situation in cases
20        such as /(a)(b)x|abc/ matched against "abc", where the return code
21        indicates that fewer than the maximum number of slots in the ovector have
22        been set.
23    
24    3.  Related to (2) above: when there are more back references in a pattern than
25        slots in the output vector, pcre_exec() uses temporary memory during
26        matching, and copies in the captures as far as possible afterwards. It was
27        using the entire output vector, but this conflicts with the specification
28        that only 2/3 is used for passing back captured substrings. Now it uses
29        only the first 2/3, for compatibility. This is, of course, another edge
30        case.
31    
32  1. Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had  4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
33     a POSIX class. After further experiments with Perl, which convinced me that      main code base, and can be used by building with --enable-jit. When this is
34     Perl has bugs and confusions, a closing square bracket is no longer allowed      done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
35     in a POSIX name.      runtime --no-jit option is given.
36    
37  2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured  5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
38     substring, but while checking the failing first alternative, substring 1 is      ovector, the return from the function was zero, implying that there were
39     temporarily captured. If the output vector supplied to pcre_exec() was not      other matches that did not fit. The correct "exactly full" value is now
40     big enough for this capture, the yield of the function was still zero      returned.
41     ("insufficient space for captured substrings"). This cannot be totally fixed  
42     without adding another stack variable, which seems a lot of expense for a  6.  If a subpattern that was called recursively or as a subroutine contained
43     edge case. However, I have improved the situation in cases such as      (*PRUNE) or any other control that caused it to give a non-standard return,
44     /(a)(b)x|abc/ matched against "abc", where the return code indicates that      invalid errors such as "Error -26 (nested recursion at the same subject
45     fewer than the maximum number of slots in the ovector have been set.      position)" or even infinite loops could occur.
46    
47  3. Related to (2) above: when there are more back references in a pattern than  7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
48     slots in the output vector, pcre_exec() uses temporary memory during      computing the minimum length on reaching *ACCEPT, and so ended up with the
49     matching, and copies in the captures as far as possible afterwards. It was      wrong value of 1 rather than 0. Further investigation indicates that
50     using the entire output vector, but this conflicts with the specification      computing a minimum subject length in the presence of *ACCEPT is difficult
51     that only 2/3 is used for passing back captured substrings. Now it uses only      (think back references, subroutine calls), and so I have changed the code
52     the first 2/3, for compatibility. This is, of course, another edge case.      so that no minimum is registered for a pattern that contains *ACCEPT.
53    
54  4. Zoltan Herczeg's just-in-time compiler support has been integrated into the  8.  If (*THEN) was present in the first (true) branch of a conditional group,
55     main code base, and can be used by building with --enable-jit.      it was not handled as intended. [But see 16 below.]
56    
57  5. When the number of matches in a pcre_dfa_exec() run exactly filled the  9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
58     ovector, the return from the function was zero, implying that there were      Sheri Pierce.
59     other matches that did not fit. The correct "exactly full" value is now  
60     returned.  10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
61        the first byte in a match must be "a".
62  6. If a subpattern that was called recursively or as a subroutine contained  
63     (*PRUNE) or any other control that caused it to give a non-standard return,  11. Change 17 for 8.13 increased the recursion depth for patterns like
64     invalid errors such as "Error -26 (nested recursion at the same subject      /a(?:.)*?a/ drastically. I've improved things by remembering whether a
65     position)" or even infinite loops could occur.      pattern contains any instances of (*THEN). If it does not, the old
66        optimizations are restored. It would be nice to do this on a per-group
67        basis, but at the moment that is not feasible.
68    
69    12. In some environments, the output of pcretest -C is CRLF terminated. This
70        broke RunTest's code that checks for the link size. A single white space
71        character after the value is now allowed for.
72    
73    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
74        For "fr", it uses the Windows-specific input and output files.
75    
76    14. If (*THEN) appeared in a group that was called recursively or as a
77        subroutine, it did not work as intended. [But see next item.]
78    
79    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
80        pattern fragments (but not containing any | characters). If A and B are
81        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
82        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
83        D. In other words, Perl considers parentheses that do not contain any |
84        characters to be part of a surrounding alternative, whereas PCRE was
85        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
86        differently. PCRE now behaves in the same way as Perl, except in the case
87        of subroutine/recursion calls such as (?1) which have in any case always
88        been different (but PCRE had them first :-).
89    
90    16. Related to 15 above: Perl does not treat the | in a conditional group as
91        creating alternatives. Such a group is treated in the same way as an
92        ordinary group without any | characters when processing (*THEN). PCRE has
93        been changed to match Perl's behaviour.
94    
95    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
96        RunGrepTest script failed.
97    
98    18. Change 22 for version 13 caused atomic groups to use more stack. This is
99        inevitable for groups that contain captures, but it can lead to a lot of
100        stack use in large patterns. The old behaviour has been restored for atomic
101        groups that do not contain any capturing parentheses.
102    
103    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
104        suppress the check for a minimum subject length at run time. (If it was
105        given to pcre_exec() or pcre_dfa_exec() it did work.)
106    
107    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
108        fail to work when decoding hex characters in data strings in EBCDIC
109        environments.
110    
111    21. It appears that in at least one Mac OS environment, the isxdigit() function
112        is implemented as a macro that evaluates to its argument more than once,
113        contravening the C 90 Standard (I haven't checked a later standard). There
114        was an instance in pcretest which caused it to go wrong when processing
115        \x{...} escapes in subject strings. The has been rewritten to avoid using
116        things like p++ in the argument of isxdigit().
117    
118    
119  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 137  Version 8.13 16-Aug-2011 Line 213  Version 8.13 16-Aug-2011
213      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
214      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
215      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
216      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
217    
218  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
219      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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