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revision 165 by ph10, Wed May 9 10:50:57 2007 UTC revision 231 by ph10, Tue Sep 11 11:15:33 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 7.2 01-May-07  Version 7.4 10-Sep-07
5    ---------------------
7    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
8        means that a class such as [\s] counted as "explicit reference to CR or
9        LF". That isn't really right - the whole point of the change was to try to
10        help when there was an actual mention of one of the two characters. So now
11        the change happens only if \r or \n (or a literal CR or LF) character is
12        encountered.
14    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
15        of both had grown to the point where there were only 3 bits left.
16        Fortunately, there was spare space in the data structure, and so I have
17        moved the internal flags into a new 16-bit field to free up more option
18        bits.
20    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
21        but did not set the internal JCHANGED flag - either of these is enough to
22        control the way the "get" function works - but the PCRE_INFO_JCHANGED
23        facility is supposed to tell if (?J) was ever used, so now (?J) at the
24        start sets both bits.
26    4.  Added options (at build time, compile time, exec time) to change \R from
27        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
30    Version 7.3 28-Aug-07
31    ---------------------
33     1. In the rejigging of the build system that eventually resulted in 7.1, the
34        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
35        brackets there is not right, since it causes compilers to look for an
36        installed pcre.h, not the version that is in the source that is being
37        compiled (which of course may be different). I have changed it back to:
39          #include "pcre.h"
41        I have a vague recollection that the change was concerned with compiling in
42        different directories, but in the new build system, that is taken care of
43        by the VPATH setting the Makefile.
45     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
46        when the subject happened to end in the byte 0x85 (e.g. if the last
47        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
48        characters but of course it shouldn't be taken as a newline when it is part
49        of another character. The bug was that, for an unlimited repeat of . in
50        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
51        characters when looking for a newline.
53     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
55     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
56        in debug output.
58     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
59        long printing in the pcrecpp unittest when running under MinGW.
61     6. ESC_K was left out of the EBCDIC table.
63     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
64        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
65        limit also applies to "virtual nesting" when a pattern is recursive, and in
66        this case 1000 isn't so big. I have been able to remove this limit at the
67        expense of backing off one optimization in certain circumstances. Normally,
68        when pcre_exec() would call its internal match() function recursively and
69        immediately return the result unconditionally, it uses a "tail recursion"
70        feature to save stack. However, when a subpattern that can match an empty
71        string has an unlimited repetition quantifier, it no longer makes this
72        optimization. That gives it a stack frame in which to save the data for
73        checking that an empty string has been matched. Previously this was taken
74        from the 1000-entry workspace that had been reserved. So now there is no
75        explicit limit, but more stack is used.
77     8. Applied Daniel's patches to solve problems with the import/export magic
78        syntax that is required for Windows, and which was going wrong for the
79        pcreposix and pcrecpp parts of the library. These were overlooked when this
80        problem was solved for the main library.
82     9. There were some crude static tests to avoid integer overflow when computing
83        the size of patterns that contain repeated groups with explicit upper
84        limits. As the maximum quantifier is 65535, the maximum group length was
85        set at 30,000 so that the product of these two numbers did not overflow a
86        32-bit integer. However, it turns out that people want to use groups that
87        are longer than 30,000 bytes (though not repeat them that many times).
88        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
89        made it possible to implement the integer overflow checks in a much more
90        dynamic way, which I have now done. The artificial limitation on group
91        length has been removed - we now have only the limit on the total length of
92        the compiled pattern, which depends on the LINK_SIZE setting.
94    10. Fixed a bug in the documentation for get/copy named substring when
95        duplicate names are permitted. If none of the named substrings are set, the
96        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
97        empty string.
99    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
100        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
101        because the ] is interpreted as the first data character and the
102        terminating ] is not found. PCRE has been made compatible with Perl in this
103        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
104        cause memory overwriting.
106    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
107        string has been matched (to stop an infinite loop). It was not recognizing
108        a conditional subpattern that could match an empty string if that
109        subpattern was within another subpattern. For example, it looped when
110        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
111        condition was not nested. This bug has been fixed.
113    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
114        past the start of the subject in the presence of bytes with the top bit
115        set, for example "\x8aBCD".
117    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
118        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
120    14. Optimized (?!) to (*FAIL).
122    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
123        This restricts code points to be within the range 0 to 0x10FFFF, excluding
124        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
125        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
126        does: it's just the validity check that is more restrictive.
128    16. Inserted checks for integer overflows during escape sequence (backslash)
129        processing, and also fixed erroneous offset values for syntax errors during
130        backslash processing.
132    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
133        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
135    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
136        caused an overrun.
138    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
139        something other than just ASCII characters) inside a group that had an
140        unlimited repeat caused a loop at compile time (while checking to see
141        whether the group could match an empty string).
143    20. Debugging a pattern containing \p or \P could cause a crash. For example,
144        [\P{Any}] did so. (Error in the code for printing property names.)
146    21. An orphan \E inside a character class could cause a crash.
148    22. A repeated capturing bracket such as (A)? could cause a wild memory
149        reference during compilation.
151    23. There are several functions in pcre_compile() that scan along a compiled
152        expression for various reasons (e.g. to see if it's fixed length for look
153        behind). There were bugs in these functions when a repeated \p or \P was
154        present in the pattern. These operators have additional parameters compared
155        with \d, etc, and these were not being taken into account when moving along
156        the compiled data. Specifically:
158        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
159            length.
161        (b) An item such as \pL+ within a repeated group could cause crashes or
162            loops.
164        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
165            "reference to non-existent subpattern" error.
167        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
169    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
170        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
172    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
174    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
175        character were causing crashes (broken optimization).
177    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
178        \p or \P) caused a compile-time loop.
180    28. More problems have arisen in unanchored patterns when CRLF is a valid line
181        break. For example, the unstudied pattern [\r\n]A does not match the string
182        "\r\nA" because change 7.0/46 below moves the current point on by two
183        characters after failing to match at the start. However, the pattern \nA
184        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
185        the same is true. There doesn't seem any very clean way out of this, but
186        what I have chosen to do makes the common cases work: PCRE now takes note
187        of whether there can be an explicit match for \r or \n anywhere in the
188        pattern, and if so, 7.0/46 no longer applies. As part of this change,
189        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
190        pattern has explicit CR or LF references.
192    29. Added (*CR) etc for changing newline setting at start of pattern.
195    Version 7.2 19-Jun-07
196  ---------------------  ---------------------
198   1. If the fr_FR locale cannot be found for test 3, try the "french" locale,   1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
# Line 22  Version 7.2 01-May-07 Line 213  Version 7.2 01-May-07
213      a small improvement under Linux. However, it saves one field in the frame      a small improvement under Linux. However, it saves one field in the frame
214      in all cases.      in all cases.
216     6. Added more features from the forthcoming Perl 5.10:
218        (a) (?-n) (where n is a string of digits) is a relative subroutine or
219            recursion call. It refers to the nth most recently opened parentheses.
221        (b) (?+n) is also a relative subroutine call; it refers to the nth next
222            to be opened parentheses.
224        (c) Conditions that refer to capturing parentheses can be specified
225            relatively, for example, (?(-2)... or (?(+3)...
227        (d) \K resets the start of the current match so that everything before
228            is not part of it.
230        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
232        (f) \g{name} is another synonym - part of Perl 5.10's unification of
233            reference syntax.
235        (g) (?| introduces a group in which the numbering of parentheses in each
236            alternative starts with the same number.
238        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
240     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
243     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
244        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
245        for detecting groups that can match an empty string.
247     9. A pattern with a very large number of alternatives (more than several
248        hundred) was running out of internal workspace during the pre-compile
249        phase, where pcre_compile() figures out how much memory will be needed. A
250        bit of new cunning has reduced the workspace needed for groups with
251        alternatives. The 1000-alternative test pattern now uses 12 bytes of
252        workspace instead of running out of the 4096 that are available.
254    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
256    11. Applied patch from Google to remove an optimization that didn't quite work.
257        The report of the bug said:
259          pcrecpp::RE("a*").FullMatch("aaa") matches, while
260          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
261          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
263    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
264        it matched the wrong number of bytes.
267  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07
268  ---------------------  ---------------------

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