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revision 165 by ph10, Wed May 9 10:50:57 2007 UTC revision 256 by ph10, Wed Sep 19 08:57:53 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.
29    5.  doc/pcresyntax.html was missing from the distribution.
31    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
32        compatibility, even though it is no longer used.
34    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
35        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
36        windows.h file is present (where different names are used).
38    8.  Changed all #include <config.h> to #include "config.h". There were also
39        some further <pcre.h> cases that I changed to "pcre.h".
41    9.  When pcregrep was used with the --colour option, it missed the line ending
42        sequence off the lines that it output.
44    10. It was pointed out to me that arrays of string pointers cause lots of
45        relocations when a shared library is dynamically loaded. A technique of
46        using a single long string with a table of offsets can drastically reduce
47        these. I have refactored PCRE in four places to do this. The result is
48        dramatic:
50          Originally:                          290
51          After changing UCP table:            187
52          After changing error message table:   43
53          After changing table of "verbs"       36
54          After changing table of Posix names   22
56        Thanks to the folks working on Gregex for glib for this insight.
58    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
59        unicode-properties was also set.
61    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
63    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
64        checked only for CRLF.
66    14. Added casts to pcretest.c to avoid compiler warnings.
68    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
71    Version 7.3 28-Aug-07
72    ---------------------
74     1. In the rejigging of the build system that eventually resulted in 7.1, the
75        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
76        brackets there is not right, since it causes compilers to look for an
77        installed pcre.h, not the version that is in the source that is being
78        compiled (which of course may be different). I have changed it back to:
80          #include "pcre.h"
82        I have a vague recollection that the change was concerned with compiling in
83        different directories, but in the new build system, that is taken care of
84        by the VPATH setting the Makefile.
86     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
87        when the subject happened to end in the byte 0x85 (e.g. if the last
88        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
89        characters but of course it shouldn't be taken as a newline when it is part
90        of another character. The bug was that, for an unlimited repeat of . in
91        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
92        characters when looking for a newline.
94     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
96     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
97        in debug output.
99     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
100        long printing in the pcrecpp unittest when running under MinGW.
102     6. ESC_K was left out of the EBCDIC table.
104     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
105        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
106        limit also applies to "virtual nesting" when a pattern is recursive, and in
107        this case 1000 isn't so big. I have been able to remove this limit at the
108        expense of backing off one optimization in certain circumstances. Normally,
109        when pcre_exec() would call its internal match() function recursively and
110        immediately return the result unconditionally, it uses a "tail recursion"
111        feature to save stack. However, when a subpattern that can match an empty
112        string has an unlimited repetition quantifier, it no longer makes this
113        optimization. That gives it a stack frame in which to save the data for
114        checking that an empty string has been matched. Previously this was taken
115        from the 1000-entry workspace that had been reserved. So now there is no
116        explicit limit, but more stack is used.
118     8. Applied Daniel's patches to solve problems with the import/export magic
119        syntax that is required for Windows, and which was going wrong for the
120        pcreposix and pcrecpp parts of the library. These were overlooked when this
121        problem was solved for the main library.
123     9. There were some crude static tests to avoid integer overflow when computing
124        the size of patterns that contain repeated groups with explicit upper
125        limits. As the maximum quantifier is 65535, the maximum group length was
126        set at 30,000 so that the product of these two numbers did not overflow a
127        32-bit integer. However, it turns out that people want to use groups that
128        are longer than 30,000 bytes (though not repeat them that many times).
129        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
130        made it possible to implement the integer overflow checks in a much more
131        dynamic way, which I have now done. The artificial limitation on group
132        length has been removed - we now have only the limit on the total length of
133        the compiled pattern, which depends on the LINK_SIZE setting.
135    10. Fixed a bug in the documentation for get/copy named substring when
136        duplicate names are permitted. If none of the named substrings are set, the
137        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
138        empty string.
140    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
141        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
142        because the ] is interpreted as the first data character and the
143        terminating ] is not found. PCRE has been made compatible with Perl in this
144        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
145        cause memory overwriting.
147    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
148        string has been matched (to stop an infinite loop). It was not recognizing
149        a conditional subpattern that could match an empty string if that
150        subpattern was within another subpattern. For example, it looped when
151        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
152        condition was not nested. This bug has been fixed.
154    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
155        past the start of the subject in the presence of bytes with the top bit
156        set, for example "\x8aBCD".
158    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
159        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
161    14. Optimized (?!) to (*FAIL).
163    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
164        This restricts code points to be within the range 0 to 0x10FFFF, excluding
165        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
166        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
167        does: it's just the validity check that is more restrictive.
169    16. Inserted checks for integer overflows during escape sequence (backslash)
170        processing, and also fixed erroneous offset values for syntax errors during
171        backslash processing.
173    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
174        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
176    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
177        caused an overrun.
179    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
180        something other than just ASCII characters) inside a group that had an
181        unlimited repeat caused a loop at compile time (while checking to see
182        whether the group could match an empty string).
184    20. Debugging a pattern containing \p or \P could cause a crash. For example,
185        [\P{Any}] did so. (Error in the code for printing property names.)
187    21. An orphan \E inside a character class could cause a crash.
189    22. A repeated capturing bracket such as (A)? could cause a wild memory
190        reference during compilation.
192    23. There are several functions in pcre_compile() that scan along a compiled
193        expression for various reasons (e.g. to see if it's fixed length for look
194        behind). There were bugs in these functions when a repeated \p or \P was
195        present in the pattern. These operators have additional parameters compared
196        with \d, etc, and these were not being taken into account when moving along
197        the compiled data. Specifically:
199        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
200            length.
202        (b) An item such as \pL+ within a repeated group could cause crashes or
203            loops.
205        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
206            "reference to non-existent subpattern" error.
208        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
210    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
211        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
213    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
215    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
216        character were causing crashes (broken optimization).
218    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
219        \p or \P) caused a compile-time loop.
221    28. More problems have arisen in unanchored patterns when CRLF is a valid line
222        break. For example, the unstudied pattern [\r\n]A does not match the string
223        "\r\nA" because change 7.0/46 below moves the current point on by two
224        characters after failing to match at the start. However, the pattern \nA
225        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
226        the same is true. There doesn't seem any very clean way out of this, but
227        what I have chosen to do makes the common cases work: PCRE now takes note
228        of whether there can be an explicit match for \r or \n anywhere in the
229        pattern, and if so, 7.0/46 no longer applies. As part of this change,
230        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
231        pattern has explicit CR or LF references.
233    29. Added (*CR) etc for changing newline setting at start of pattern.
236    Version 7.2 19-Jun-07
237  ---------------------  ---------------------
239   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 254  Version 7.2 01-May-07
254      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
255      in all cases.      in all cases.
257     6. Added more features from the forthcoming Perl 5.10:
259        (a) (?-n) (where n is a string of digits) is a relative subroutine or
260            recursion call. It refers to the nth most recently opened parentheses.
262        (b) (?+n) is also a relative subroutine call; it refers to the nth next
263            to be opened parentheses.
265        (c) Conditions that refer to capturing parentheses can be specified
266            relatively, for example, (?(-2)... or (?(+3)...
268        (d) \K resets the start of the current match so that everything before
269            is not part of it.
271        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
273        (f) \g{name} is another synonym - part of Perl 5.10's unification of
274            reference syntax.
276        (g) (?| introduces a group in which the numbering of parentheses in each
277            alternative starts with the same number.
279        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
281     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
284     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
285        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
286        for detecting groups that can match an empty string.
288     9. A pattern with a very large number of alternatives (more than several
289        hundred) was running out of internal workspace during the pre-compile
290        phase, where pcre_compile() figures out how much memory will be needed. A
291        bit of new cunning has reduced the workspace needed for groups with
292        alternatives. The 1000-alternative test pattern now uses 12 bytes of
293        workspace instead of running out of the 4096 that are available.
295    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
297    11. Applied patch from Google to remove an optimization that didn't quite work.
298        The report of the bug said:
300          pcrecpp::RE("a*").FullMatch("aaa") matches, while
301          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
302          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
304    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
305        it matched the wrong number of bytes.
308  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07
309  ---------------------  ---------------------

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