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revision 687 by ph10, Tue Sep 6 16:09:43 2011 UTC revision 743 by ph10, Tue Nov 8 09:59:38 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.20  Version 8.21
5  ------------  ------------
6    
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  2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10     in a POSIX name.      are added as well.
11    
12  2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured  3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13     substring, but while checking the failing first alternative, substring 1 is      PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14     temporarily captured. If the output vector supplied to pcre_exec() was not      calling _pcre_jit_exec. Some extra comments are added.
15     big enough for this capture, the yield of the function was still zero  
16     ("insufficient space for captured substrings"). This cannot be totally fixed  4.  Mark settings inside atomic groups that do not contain any capturing
17     without adding another stack variable, which seems a lot of expense for a      parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18     edge case. However, I have improved the situation in cases such as      was introduced by change 18 for 8.20.
19     /(a)(b)x|abc/ matched against "abc", where the return code indicates that  
20     fewer than the maximum number of slots in the ovector have been set.  
21    Version 8.20 21-Oct-2011
22  3. Related to (2) above: when there are more back references in a pattern than  ------------------------
23     slots in the output vector, pcre_exec() uses temporary memory during  
24     matching, and copies in the captures as far as possible afterwards. It was  1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
25     using the entire output vector, but this conflicts with the specification      a POSIX class. After further experiments with Perl, which convinced me that
26     that only 2/3 is used for passing back captured substrings. Now it uses only      Perl has bugs and confusions, a closing square bracket is no longer allowed
27     the first 2/3, for compatibility. This is, of course, another edge case.      in a POSIX name. This bug also affected patterns with classes that started
28        with full stops.
29  4. Zoltan Herczeg's just-in-time compiler support has been integrated into the  
30     main code base, and can be used by building with --enable-jit. When this is  2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
31     done, pcregrep automatically uses it unless --disable-pcregrep-jit or the      captured substring, but while checking the failing first alternative,
32     runtime --no-jit option is given.      substring 1 is temporarily captured. If the output vector supplied to
33        pcre_exec() was not big enough for this capture, the yield of the function
34  5. When the number of matches in a pcre_dfa_exec() run exactly filled the      was still zero ("insufficient space for captured substrings"). This cannot
35     ovector, the return from the function was zero, implying that there were      be totally fixed without adding another stack variable, which seems a lot
36     other matches that did not fit. The correct "exactly full" value is now      of expense for a edge case. However, I have improved the situation in cases
37     returned.      such as /(a)(b)x|abc/ matched against "abc", where the return code
38        indicates that fewer than the maximum number of slots in the ovector have
39  6. If a subpattern that was called recursively or as a subroutine contained      been set.
40     (*PRUNE) or any other control that caused it to give a non-standard return,  
41     invalid errors such as "Error -26 (nested recursion at the same subject  3.  Related to (2) above: when there are more back references in a pattern than
42     position)" or even infinite loops could occur.      slots in the output vector, pcre_exec() uses temporary memory during
43        matching, and copies in the captures as far as possible afterwards. It was
44        using the entire output vector, but this conflicts with the specification
45        that only 2/3 is used for passing back captured substrings. Now it uses
46        only the first 2/3, for compatibility. This is, of course, another edge
47        case.
48    
49    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
50        main code base, and can be used by building with --enable-jit. When this is
51        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
52        runtime --no-jit option is given.
53    
54    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
55        ovector, the return from the function was zero, implying that there were
56        other matches that did not fit. The correct "exactly full" value is now
57        returned.
58    
59    6.  If a subpattern that was called recursively or as a subroutine contained
60        (*PRUNE) or any other control that caused it to give a non-standard return,
61        invalid errors such as "Error -26 (nested recursion at the same subject
62        position)" or even infinite loops could occur.
63    
64    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
65        computing the minimum length on reaching *ACCEPT, and so ended up with the
66        wrong value of 1 rather than 0. Further investigation indicates that
67        computing a minimum subject length in the presence of *ACCEPT is difficult
68        (think back references, subroutine calls), and so I have changed the code
69        so that no minimum is registered for a pattern that contains *ACCEPT.
70    
71    8.  If (*THEN) was present in the first (true) branch of a conditional group,
72        it was not handled as intended. [But see 16 below.]
73    
74    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
75        Sheri Pierce.
76    
77    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
78        the first byte in a match must be "a".
79    
80    11. Change 17 for 8.13 increased the recursion depth for patterns like
81        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
82        pattern contains any instances of (*THEN). If it does not, the old
83        optimizations are restored. It would be nice to do this on a per-group
84        basis, but at the moment that is not feasible.
85    
86    12. In some environments, the output of pcretest -C is CRLF terminated. This
87        broke RunTest's code that checks for the link size. A single white space
88        character after the value is now allowed for.
89    
90    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
91        For "fr", it uses the Windows-specific input and output files.
92    
93    14. If (*THEN) appeared in a group that was called recursively or as a
94        subroutine, it did not work as intended. [But see next item.]
95    
96    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
97        pattern fragments (but not containing any | characters). If A and B are
98        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
99        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
100        D. In other words, Perl considers parentheses that do not contain any |
101        characters to be part of a surrounding alternative, whereas PCRE was
102        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
103        differently. PCRE now behaves in the same way as Perl, except in the case
104        of subroutine/recursion calls such as (?1) which have in any case always
105        been different (but PCRE had them first :-).
106    
107    16. Related to 15 above: Perl does not treat the | in a conditional group as
108        creating alternatives. Such a group is treated in the same way as an
109        ordinary group without any | characters when processing (*THEN). PCRE has
110        been changed to match Perl's behaviour.
111    
112    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
113        RunGrepTest script failed.
114    
115    18. Change 22 for version 13 caused atomic groups to use more stack. This is
116        inevitable for groups that contain captures, but it can lead to a lot of
117        stack use in large patterns. The old behaviour has been restored for atomic
118        groups that do not contain any capturing parentheses.
119    
120    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
121        suppress the check for a minimum subject length at run time. (If it was
122        given to pcre_exec() or pcre_dfa_exec() it did work.)
123    
124    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
125        fail to work when decoding hex characters in data strings in EBCDIC
126        environments.
127    
128    21. It appears that in at least one Mac OS environment, the isxdigit() function
129        is implemented as a macro that evaluates to its argument more than once,
130        contravening the C 90 Standard (I haven't checked a later standard). There
131        was an instance in pcretest which caused it to go wrong when processing
132        \x{...} escapes in subject strings. The has been rewritten to avoid using
133        things like p++ in the argument of isxdigit().
134    
135    
136  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 139  Version 8.13 16-Aug-2011 Line 230  Version 8.13 16-Aug-2011
230      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
231      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
232      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
233      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
234    
235  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
236      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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