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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 102 by ph10, Tue Mar 6 15:50:45 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 05-Mar-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The maintain/132html script that I use to
25        generate HTML has been updated to handle .nf/.fi and to complain if it
26        encounters .br or .in.
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, for the benefit
30        of those who have to compile without Autotools (compare pcre.h).
32     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
33        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
34        makevp.bat for the current PCRE, using the additional files !compile.txt,
35        !linklib.txt, and pcregexp.pas.
37     6. A Windows user reported a minor discrepancy with test 2, which turned out
38        to be caused by a trailing space on an input line that had got lost in his
39        copy. The trailing space was an accident, so I've just removed it.
42    Version 7.0 19-Dec-06
43    ---------------------
45     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
46        moving to gcc 4.1.1.
48     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
49        sys/time.h, which is documented as needed for this function. It doesn't
50        seem to matter on Linux, but it showed up on some releases of OS X.
52     3. It seems that there are systems where bytes whose values are greater than
53        127 match isprint() in the "C" locale. The "C" locale should be the
54        default when a C program starts up. In most systems, only ASCII printing
55        characters match isprint(). This difference caused the output from pcretest
56        to vary, making some of the tests fail. I have changed pcretest so that:
58        (a) When it is outputting text in the compiled version of a pattern, bytes
59            other than 32-126 are always shown as hex escapes.
61        (b) When it is outputting text that is a matched part of a subject string,
62            it does the same, unless a different locale has been set for the match
63            (using the /L modifier). In this case, it uses isprint() to decide.
65     4. Fixed a major bug that caused incorrect computation of the amount of memory
66        required for a compiled pattern when options that changed within the
67        pattern affected the logic of the preliminary scan that determines the
68        length. The relevant options are -x, and -i in UTF-8 mode. The result was
69        that the computed length was too small. The symptoms of this bug were
70        either the PCRE error "internal error: code overflow" from pcre_compile(),
71        or a glibc crash with a message such as "pcretest: free(): invalid next
72        size (fast)". Examples of patterns that provoked this bug (shown in
73        pcretest format) are:
75          /(?-x: )/x
76          /(?x)(?-x: \s*#\s*)/
77          /((?i)[\x{c0}])/8
78          /(?i:[\x{c0}])/8
80        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
81        is now done differently.
83     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
84        wrapper classes; (b) implement a new function in the C++ scanner that is
85        more efficient than the old way of doing things because it avoids levels of
86        recursion in the regex matching; (c) add a paragraph to the documentation
87        for the FullMatch() function.
89     6. The escape sequence \n was being treated as whatever was defined as
90        "newline". Not only was this contrary to the documentation, which states
91        that \n is character 10 (hex 0A), but it also went horribly wrong when
92        "newline" was defined as CRLF. This has been fixed.
94     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
95        was being set to -1 for the "end of line" case (supposedly a value that no
96        character can have). Though this value is never used (the check for end of
97        line is "zero bytes in current character"), it caused compiler complaints.
98        I've changed it to 0xffffffff.
100     8. In pcre_version.c, the version string was being built by a sequence of
101        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
102        string (as it is for production releases) called a macro with an empty
103        argument. The C standard says the result of this is undefined. The gcc
104        compiler treats it as an empty string (which was what was wanted) but it is
105        reported that Visual C gives an error. The source has been hacked around to
106        avoid this problem.
108     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
109        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
110        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
111        of them did).
113    10. Originally, pcretest opened its input and output without "b"; then I was
114        told that "b" was needed in some environments, so it was added for release
115        5.0 to both the input and output. (It makes no difference on Unix-like
116        systems.) Later I was told that it is wrong for the input on Windows. I've
117        now abstracted the modes into two macros, to make it easier to fiddle with
118        them, and removed "b" from the input mode under Windows.
120    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
122    12. Added -help and --help to pcretest as an official way of being reminded
123        of the options.
125    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
126        and pcrecpp.cc because they annoy compilers at high warning levels.
128    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
130    15. Fixed an occurrence of == in configure.ac that should have been = (shell
131        scripts are not C programs :-) and which was not noticed because it works
132        on Linux.
134    16. pcretest is supposed to handle any length of pattern and data line (as one
135        line or as a continued sequence of lines) by extending its input buffer if
136        necessary. This feature was broken for very long pattern lines, leading to
137        a string of junk being passed to pcre_compile() if the pattern was longer
138        than about 50K.
140    17. I have done a major re-factoring of the way pcre_compile() computes the
141        amount of memory needed for a compiled pattern. Previously, there was code
142        that made a preliminary scan of the pattern in order to do this. That was
143        OK when PCRE was new, but as the facilities have expanded, it has become
144        harder and harder to keep it in step with the real compile phase, and there
145        have been a number of bugs (see for example, 4 above). I have now found a
146        cunning way of running the real compile function in a "fake" mode that
147        enables it to compute how much memory it would need, while actually only
148        ever using a few hundred bytes of working memory and without too many
149        tests of the mode. This should make future maintenance and development
150        easier. A side effect of this work is that the limit of 200 on the nesting
151        depth of parentheses has been removed (though this was never a serious
152        limitation, I suspect). However, there is a downside: pcre_compile() now
153        runs more slowly than before (30% or more, depending on the pattern). I
154        hope this isn't a big issue. There is no effect on runtime performance.
156    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
157        newline (only possible for the last line of a file) and it was a
158        pattern that set a locale (followed by /Lsomething), pcretest crashed.
160    19. Added additional timing features to pcretest. (1) The -tm option now times
161        matching only, not compiling. (2) Both -t and -tm can be followed, as a
162        separate command line item, by a number that specifies the number of
163        repeats to use when timing. The default is 50000; this gives better
164        precision, but takes uncomfortably long for very large patterns.
166    20. Extended pcre_study() to be more clever in cases where a branch of a
167        subpattern has no definite first character. For example, (a*|b*)[cd] would
168        previously give no result from pcre_study(). Now it recognizes that the
169        first character must be a, b, c, or d.
171    21. There was an incorrect error "recursive call could loop indefinitely" if
172        a subpattern (or the entire pattern) that was being tested for matching an
173        empty string contained only one non-empty item after a nested subpattern.
174        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
175        incorrectly, because the \d was being skipped in the check.
177    22. The pcretest program now has a new pattern option /B and a command line
178        option -b, which is equivalent to adding /B to every pattern. This causes
179        it to show the compiled bytecode, without the additional information that
180        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
181        is the same as /B/I).
183    23. A new optimization is now able automatically to treat some sequences such
184        as a*b as a*+b. More specifically, if something simple (such as a character
185        or a simple class like \d) has an unlimited quantifier, and is followed by
186        something that cannot possibly match the quantified thing, the quantifier
187        is automatically "possessified".
189    24. A recursive reference to a subpattern whose number was greater than 39
190        went wrong under certain circumstances in UTF-8 mode. This bug could also
191        have affected the operation of pcre_study().
193    25. Realized that a little bit of performance could be had by replacing
194        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
196    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
198    27. Possessive quantifiers such as a++ were previously implemented by turning
199        them into atomic groups such as ($>a+). Now they have their own opcodes,
200        which improves performance. This includes the automatically created ones
201        from 23 above.
203    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
204        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
205        the first matched character to be a colon. This applied both to named and
206        numbered groups.
208    29. The ucpinternal.h header file was missing its idempotency #ifdef.
210    30. I was sent a "project" file called libpcre.a.dev which I understand makes
211        building PCRE on Windows easier, so I have included it in the distribution.
213    31. There is now a check in pcretest against a ridiculously large number being
214        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
215        loop, the loop is abandoned.
217    32. Forward references to subpatterns in conditions such as (?(2)...) where
218        subpattern 2 is defined later cause pcre_compile() to search forwards in
219        the pattern for the relevant set of parentheses. This search went wrong
220        when there were unescaped parentheses in a character class, parentheses
221        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
223    33. "Subroutine" calls and backreferences were previously restricted to
224        referencing subpatterns earlier in the regex. This restriction has now
225        been removed.
227    34. Added a number of extra features that are going to be in Perl 5.10. On the
228        whole, these are just syntactic alternatives for features that PCRE had
229        previously implemented using the Python syntax or my own invention. The
230        other formats are all retained for compatibility.
232        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
233            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
234            also .NET compatible.
236        (b) A recursion or subroutine call to a named group can now be defined as
237            (?&name) as well as (?P>name).
239        (c) A backreference to a named group can now be defined as \k<name> or
240            \k'name' as well as (?P=name). The new forms, as well as being in Perl
241            5.10, are also .NET compatible.
243        (d) A conditional reference to a named group can now use the syntax
244            (?(<name>) or (?('name') as well as (?(name).
246        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
247            groups (named and numbered) that are never evaluated inline, but can be
248            called as "subroutines" from elsewhere. In effect, the DEFINE condition
249            is always false. There may be only one alternative in such a group.
251        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
252            as the simple (?(R). The condition is true only if the most recent
253            recursion is that of the given number or name. It does not search out
254            through the entire recursion stack.
256        (g) The escape \gN or \g{N} has been added, where N is a positive or
257            negative number, specifying an absolute or relative reference.
259    35. Tidied to get rid of some further signed/unsigned compiler warnings and
260        some "unreachable code" warnings.
262    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
263        things, this adds five new scripts.
265    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
266        There were also incompatibilities regarding the handling of \Q..\E inside
267        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
268        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
270    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
271        matches an empty string, and forcibly breaks the loop. There were bugs in
272        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
273        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
274        separate and independent bugs (that affected different cases) have been
275        fixed.
277    39. Refactored the code to abolish the use of different opcodes for small
278        capturing bracket numbers. This is a tidy that I avoided doing when I
279        removed the limit on the number of capturing brackets for 3.5 back in 2001.
280        The new approach is not only tidier, it makes it possible to reduce the
281        memory needed to fix the previous bug (38).
283    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
284        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
285        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
286        mode.
288    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
289        report.
291    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
292        copy construction and assignment in the C++ wrapper.
294    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
295        couple of bugs that could have given wrong results in the "--newline=crlf"
296        case.
298    44. Added a number of casts and did some reorganization of signed/unsigned int
299        variables following suggestions from Dair Grant. Also renamed the variable
300        "this" as "item" because it is a C++ keyword.
302    45. Arranged for dftables to add
304          #include "pcre_internal.h"
306        to pcre_chartables.c because without it, gcc 4.x may remove the array
307        definition from the final binary if PCRE is built into a static library and
308        dead code stripping is activated.
310    46. For an unanchored pattern, if a match attempt fails at the start of a
311        newline sequence, and the newline setting is CRLF or ANY, and the next two
312        characters are CRLF, advance by two characters instead of one.
315  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
316  ---------------------  ---------------------

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