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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 267 by ph10, Wed Nov 14 11:48:49 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.5 12-Nov-07
5    ---------------------
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
22    Version 7.4 21-Sep-07
23    ---------------------
25    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
26        means that a class such as [\s] counted as "explicit reference to CR or
27        LF". That isn't really right - the whole point of the change was to try to
28        help when there was an actual mention of one of the two characters. So now
29        the change happens only if \r or \n (or a literal CR or LF) character is
30        encountered.
32    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
33        of both had grown to the point where there were only 3 bits left.
34        Fortunately, there was spare space in the data structure, and so I have
35        moved the internal flags into a new 16-bit field to free up more option
36        bits.
38    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
39        but did not set the internal JCHANGED flag - either of these is enough to
40        control the way the "get" function works - but the PCRE_INFO_JCHANGED
41        facility is supposed to tell if (?J) was ever used, so now (?J) at the
42        start sets both bits.
44    4.  Added options (at build time, compile time, exec time) to change \R from
45        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
47    5.  doc/pcresyntax.html was missing from the distribution.
49    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
50        compatibility, even though it is no longer used.
52    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
53        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
54        windows.h file is present (where different names are used). [This was
55        reversed later after testing - see 16 below.]
57    8.  Changed all #include <config.h> to #include "config.h". There were also
58        some further <pcre.h> cases that I changed to "pcre.h".
60    9.  When pcregrep was used with the --colour option, it missed the line ending
61        sequence off the lines that it output.
63    10. It was pointed out to me that arrays of string pointers cause lots of
64        relocations when a shared library is dynamically loaded. A technique of
65        using a single long string with a table of offsets can drastically reduce
66        these. I have refactored PCRE in four places to do this. The result is
67        dramatic:
69          Originally:                          290
70          After changing UCP table:            187
71          After changing error message table:   43
72          After changing table of "verbs"       36
73          After changing table of Posix names   22
75        Thanks to the folks working on Gregex for glib for this insight.
77    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
78        unicode-properties was also set.
80    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
82    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
83        checked only for CRLF.
85    14. Added casts to pcretest.c to avoid compiler warnings.
87    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
89    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
90        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
91        entirely. This removes changes made in 7 above.
93    17. The CMake files have been updated, and there is now more information about
94        building with CMake in the NON-UNIX-USE document.
97    Version 7.3 28-Aug-07
98    ---------------------
100     1. In the rejigging of the build system that eventually resulted in 7.1, the
101        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
102        brackets there is not right, since it causes compilers to look for an
103        installed pcre.h, not the version that is in the source that is being
104        compiled (which of course may be different). I have changed it back to:
106          #include "pcre.h"
108        I have a vague recollection that the change was concerned with compiling in
109        different directories, but in the new build system, that is taken care of
110        by the VPATH setting the Makefile.
112     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
113        when the subject happened to end in the byte 0x85 (e.g. if the last
114        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
115        characters but of course it shouldn't be taken as a newline when it is part
116        of another character. The bug was that, for an unlimited repeat of . in
117        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
118        characters when looking for a newline.
120     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
122     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
123        in debug output.
125     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
126        long printing in the pcrecpp unittest when running under MinGW.
128     6. ESC_K was left out of the EBCDIC table.
130     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
131        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
132        limit also applies to "virtual nesting" when a pattern is recursive, and in
133        this case 1000 isn't so big. I have been able to remove this limit at the
134        expense of backing off one optimization in certain circumstances. Normally,
135        when pcre_exec() would call its internal match() function recursively and
136        immediately return the result unconditionally, it uses a "tail recursion"
137        feature to save stack. However, when a subpattern that can match an empty
138        string has an unlimited repetition quantifier, it no longer makes this
139        optimization. That gives it a stack frame in which to save the data for
140        checking that an empty string has been matched. Previously this was taken
141        from the 1000-entry workspace that had been reserved. So now there is no
142        explicit limit, but more stack is used.
144     8. Applied Daniel's patches to solve problems with the import/export magic
145        syntax that is required for Windows, and which was going wrong for the
146        pcreposix and pcrecpp parts of the library. These were overlooked when this
147        problem was solved for the main library.
149     9. There were some crude static tests to avoid integer overflow when computing
150        the size of patterns that contain repeated groups with explicit upper
151        limits. As the maximum quantifier is 65535, the maximum group length was
152        set at 30,000 so that the product of these two numbers did not overflow a
153        32-bit integer. However, it turns out that people want to use groups that
154        are longer than 30,000 bytes (though not repeat them that many times).
155        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
156        made it possible to implement the integer overflow checks in a much more
157        dynamic way, which I have now done. The artificial limitation on group
158        length has been removed - we now have only the limit on the total length of
159        the compiled pattern, which depends on the LINK_SIZE setting.
161    10. Fixed a bug in the documentation for get/copy named substring when
162        duplicate names are permitted. If none of the named substrings are set, the
163        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
164        empty string.
166    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
167        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
168        because the ] is interpreted as the first data character and the
169        terminating ] is not found. PCRE has been made compatible with Perl in this
170        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
171        cause memory overwriting.
173    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
174        string has been matched (to stop an infinite loop). It was not recognizing
175        a conditional subpattern that could match an empty string if that
176        subpattern was within another subpattern. For example, it looped when
177        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
178        condition was not nested. This bug has been fixed.
180    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
181        past the start of the subject in the presence of bytes with the top bit
182        set, for example "\x8aBCD".
184    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
185        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
187    14. Optimized (?!) to (*FAIL).
189    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
190        This restricts code points to be within the range 0 to 0x10FFFF, excluding
191        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
192        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
193        does: it's just the validity check that is more restrictive.
195    16. Inserted checks for integer overflows during escape sequence (backslash)
196        processing, and also fixed erroneous offset values for syntax errors during
197        backslash processing.
199    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
200        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
202    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
203        caused an overrun.
205    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
206        something other than just ASCII characters) inside a group that had an
207        unlimited repeat caused a loop at compile time (while checking to see
208        whether the group could match an empty string).
210    20. Debugging a pattern containing \p or \P could cause a crash. For example,
211        [\P{Any}] did so. (Error in the code for printing property names.)
213    21. An orphan \E inside a character class could cause a crash.
215    22. A repeated capturing bracket such as (A)? could cause a wild memory
216        reference during compilation.
218    23. There are several functions in pcre_compile() that scan along a compiled
219        expression for various reasons (e.g. to see if it's fixed length for look
220        behind). There were bugs in these functions when a repeated \p or \P was
221        present in the pattern. These operators have additional parameters compared
222        with \d, etc, and these were not being taken into account when moving along
223        the compiled data. Specifically:
225        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
226            length.
228        (b) An item such as \pL+ within a repeated group could cause crashes or
229            loops.
231        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
232            "reference to non-existent subpattern" error.
234        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
236    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
237        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
239    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
241    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
242        character were causing crashes (broken optimization).
244    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
245        \p or \P) caused a compile-time loop.
247    28. More problems have arisen in unanchored patterns when CRLF is a valid line
248        break. For example, the unstudied pattern [\r\n]A does not match the string
249        "\r\nA" because change 7.0/46 below moves the current point on by two
250        characters after failing to match at the start. However, the pattern \nA
251        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
252        the same is true. There doesn't seem any very clean way out of this, but
253        what I have chosen to do makes the common cases work: PCRE now takes note
254        of whether there can be an explicit match for \r or \n anywhere in the
255        pattern, and if so, 7.0/46 no longer applies. As part of this change,
256        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
257        pattern has explicit CR or LF references.
259    29. Added (*CR) etc for changing newline setting at start of pattern.
262    Version 7.2 19-Jun-07
263    ---------------------
265     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
266        which is apparently normally available under Windows.
268     2. Re-jig the pcregrep tests with different newline settings in an attempt
269        to make them independent of the local environment's newline setting.
271     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
273     4. Some of the "internals" tests were previously cut out when the link size
274        was not 2, because the output contained actual offsets. The recent new
275        "Z" feature of pcretest means that these can be cut out, making the tests
276        usable with all link sizes.
278     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
279        stack recursion. This gives a massive performance boost under BSD, but just
280        a small improvement under Linux. However, it saves one field in the frame
281        in all cases.
283     6. Added more features from the forthcoming Perl 5.10:
285        (a) (?-n) (where n is a string of digits) is a relative subroutine or
286            recursion call. It refers to the nth most recently opened parentheses.
288        (b) (?+n) is also a relative subroutine call; it refers to the nth next
289            to be opened parentheses.
291        (c) Conditions that refer to capturing parentheses can be specified
292            relatively, for example, (?(-2)... or (?(+3)...
294        (d) \K resets the start of the current match so that everything before
295            is not part of it.
297        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
299        (f) \g{name} is another synonym - part of Perl 5.10's unification of
300            reference syntax.
302        (g) (?| introduces a group in which the numbering of parentheses in each
303            alternative starts with the same number.
305        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
307     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
310     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
311        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
312        for detecting groups that can match an empty string.
314     9. A pattern with a very large number of alternatives (more than several
315        hundred) was running out of internal workspace during the pre-compile
316        phase, where pcre_compile() figures out how much memory will be needed. A
317        bit of new cunning has reduced the workspace needed for groups with
318        alternatives. The 1000-alternative test pattern now uses 12 bytes of
319        workspace instead of running out of the 4096 that are available.
321    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
323    11. Applied patch from Google to remove an optimization that didn't quite work.
324        The report of the bug said:
326          pcrecpp::RE("a*").FullMatch("aaa") matches, while
327          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
328          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
330    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
331        it matched the wrong number of bytes.
334    Version 7.1 24-Apr-07
335    ---------------------
337     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
338        that is more "standard", making use of automake and other Autotools. There
339        is some re-arrangement of the files and adjustment of comments consequent
340        on this.
342     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
343        for recursive directory scanning broke on some systems because the files
344        are not scanned in any specific order and on different systems the order
345        was different. A call to "sort" has been inserted into RunGrepTest for the
346        approprate test as a short-term fix. In the longer term there may be an
347        alternative.
349     3. I had an email from Eric Raymond about problems translating some of PCRE's
350        man pages to HTML (despite the fact that I distribute HTML pages, some
351        people do their own conversions for various reasons). The problems
352        concerned the use of low-level troff macros .br and .in. I have therefore
353        removed all such uses from the man pages (some were redundant, some could
354        be replaced by .nf/.fi pairs). The 132html script that I use to generate
355        HTML has been updated to handle .nf/.fi and to complain if it encounters
356        .br or .in.
358     4. Updated comments in configure.ac that get placed in config.h.in and also
359        arranged for config.h to be included in the distribution, with the name
360        config.h.generic, for the benefit of those who have to compile without
361        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
363     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
364        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
365        makevp.bat for the current PCRE, using the additional files
366        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
368     6. A Windows user reported a minor discrepancy with test 2, which turned out
369        to be caused by a trailing space on an input line that had got lost in his
370        copy. The trailing space was an accident, so I've just removed it.
372     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
373        that is needed.
375     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
376        as "const" (a) because they are and (b) because it helps the PHP
377        maintainers who have recently made a script to detect big data structures
378        in the php code that should be moved to the .rodata section. I remembered
379        to update Builducptable as well, so it won't revert if ucptable.h is ever
380        re-created.
382     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
383        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
384        order to be able to cut out the UTF-8 tables in the latter when UTF-8
385        support is not required. This saves 1.5-2K of code, which is important in
386        some applications.
388        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
389        so as not to refer to the tables, even though these functions will never be
390        called when UTF-8 support is disabled. Otherwise there are problems with a
391        shared library.
393    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
395        (a) It was defining its arguments as char * instead of void *.
397        (b) It was assuming that all moves were upwards in memory; this was true
398            a long time ago when I wrote it, but is no longer the case.
400        The emulated memove() is provided for those environments that have neither
401        memmove() nor bcopy(). I didn't think anyone used it these days, but that
402        is clearly not the case, as these two bugs were recently reported.
404    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
405        and Detrail to create the HTML documentation, the .txt form of the man
406        pages, and it removes trailing spaces from listed files. It also creates
407        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
408        case, it wraps all the #defines with #ifndefs. This script should be run
409        before "make dist".
411    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
412        with Unicode property support.
414        (a) For a maximizing quantifier, if the two different cases of the
415            character were of different lengths in their UTF-8 codings (there are
416            some cases like this - I found 11), and the matching function had to
417            back up over a mixture of the two cases, it incorrectly assumed they
418            were both the same length.
420        (b) When PCRE was configured to use the heap rather than the stack for
421            recursion during matching, it was not correctly preserving the data for
422            the other case of a UTF-8 character when checking ahead for a match
423            while processing a minimizing repeat. If the check also involved
424            matching a wide character, but failed, corruption could cause an
425            erroneous result when trying to check for a repeat of the original
426            character.
428    13. Some tidying changes to the testing mechanism:
430        (a) The RunTest script now detects the internal link size and whether there
431            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
432            values substituted by "configure". (The RunGrepTest script already did
433            this for UTF-8.) The configure.ac script no longer substitutes the
434            relevant variables.
436        (b) The debugging options /B and /D in pcretest show the compiled bytecode
437            with length and offset values. This means that the output is different
438            for different internal link sizes. Test 2 is skipped for link sizes
439            other than 2 because of this, bypassing the problem. Unfortunately,
440            there was also a test in test 3 (the locale tests) that used /B and
441            failed for link sizes other than 2. Rather than cut the whole test out,
442            I have added a new /Z option to pcretest that replaces the length and
443            offset values with spaces. This is now used to make test 3 independent
444            of link size. (Test 2 will be tidied up later.)
446    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
447        segmentation fault instead of returning the appropriate error message.
449    15. In multiline mode when the newline sequence was set to "any", the pattern
450        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
451        This doesn't seem right; it now treats the CRLF combination as the line
452        ending, and so does not match in that case. It's only a pattern such as ^$
453        that would hit this one: something like ^ABC$ would have failed after \r
454        and then tried again after \r\n.
456    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
457        in an attempt to make files that differ only in their line terminators
458        compare equal. This works on Linux.
460    17. Under certain error circumstances pcregrep might try to free random memory
461        as it exited. This is now fixed, thanks to valgrind.
463    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
464        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
465        was because its rules for how to advance for /g after matching an empty
466        string at the end of a line did not allow for this case. They now check for
467        it specially.
469    20. pcretest is supposed to handle patterns and data of any length, by
470        extending its buffers when necessary. It was getting this wrong when the
471        buffer for a data line had to be extended.
473    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
474        CRLF as a newline sequence.
476    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
477        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
478        I have nevertheless tidied it up.
480    23. Added some casts to kill warnings from HP-UX ia64 compiler.
482    24. Added a man page for pcre-config.
485    Version 7.0 19-Dec-06
486    ---------------------
488     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
489        moving to gcc 4.1.1.
491     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
492        sys/time.h, which is documented as needed for this function. It doesn't
493        seem to matter on Linux, but it showed up on some releases of OS X.
495     3. It seems that there are systems where bytes whose values are greater than
496        127 match isprint() in the "C" locale. The "C" locale should be the
497        default when a C program starts up. In most systems, only ASCII printing
498        characters match isprint(). This difference caused the output from pcretest
499        to vary, making some of the tests fail. I have changed pcretest so that:
501        (a) When it is outputting text in the compiled version of a pattern, bytes
502            other than 32-126 are always shown as hex escapes.
504        (b) When it is outputting text that is a matched part of a subject string,
505            it does the same, unless a different locale has been set for the match
506            (using the /L modifier). In this case, it uses isprint() to decide.
508     4. Fixed a major bug that caused incorrect computation of the amount of memory
509        required for a compiled pattern when options that changed within the
510        pattern affected the logic of the preliminary scan that determines the
511        length. The relevant options are -x, and -i in UTF-8 mode. The result was
512        that the computed length was too small. The symptoms of this bug were
513        either the PCRE error "internal error: code overflow" from pcre_compile(),
514        or a glibc crash with a message such as "pcretest: free(): invalid next
515        size (fast)". Examples of patterns that provoked this bug (shown in
516        pcretest format) are:
518          /(?-x: )/x
519          /(?x)(?-x: \s*#\s*)/
520          /((?i)[\x{c0}])/8
521          /(?i:[\x{c0}])/8
523        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
524        is now done differently.
526     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
527        wrapper classes; (b) implement a new function in the C++ scanner that is
528        more efficient than the old way of doing things because it avoids levels of
529        recursion in the regex matching; (c) add a paragraph to the documentation
530        for the FullMatch() function.
532     6. The escape sequence \n was being treated as whatever was defined as
533        "newline". Not only was this contrary to the documentation, which states
534        that \n is character 10 (hex 0A), but it also went horribly wrong when
535        "newline" was defined as CRLF. This has been fixed.
537     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
538        was being set to -1 for the "end of line" case (supposedly a value that no
539        character can have). Though this value is never used (the check for end of
540        line is "zero bytes in current character"), it caused compiler complaints.
541        I've changed it to 0xffffffff.
543     8. In pcre_version.c, the version string was being built by a sequence of
544        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
545        string (as it is for production releases) called a macro with an empty
546        argument. The C standard says the result of this is undefined. The gcc
547        compiler treats it as an empty string (which was what was wanted) but it is
548        reported that Visual C gives an error. The source has been hacked around to
549        avoid this problem.
551     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
552        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
553        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
554        of them did).
556    10. Originally, pcretest opened its input and output without "b"; then I was
557        told that "b" was needed in some environments, so it was added for release
558        5.0 to both the input and output. (It makes no difference on Unix-like
559        systems.) Later I was told that it is wrong for the input on Windows. I've
560        now abstracted the modes into two macros, to make it easier to fiddle with
561        them, and removed "b" from the input mode under Windows.
563    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
565    12. Added -help and --help to pcretest as an official way of being reminded
566        of the options.
568    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
569        and pcrecpp.cc because they annoy compilers at high warning levels.
571    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
573    15. Fixed an occurrence of == in configure.ac that should have been = (shell
574        scripts are not C programs :-) and which was not noticed because it works
575        on Linux.
577    16. pcretest is supposed to handle any length of pattern and data line (as one
578        line or as a continued sequence of lines) by extending its input buffer if
579        necessary. This feature was broken for very long pattern lines, leading to
580        a string of junk being passed to pcre_compile() if the pattern was longer
581        than about 50K.
583    17. I have done a major re-factoring of the way pcre_compile() computes the
584        amount of memory needed for a compiled pattern. Previously, there was code
585        that made a preliminary scan of the pattern in order to do this. That was
586        OK when PCRE was new, but as the facilities have expanded, it has become
587        harder and harder to keep it in step with the real compile phase, and there
588        have been a number of bugs (see for example, 4 above). I have now found a
589        cunning way of running the real compile function in a "fake" mode that
590        enables it to compute how much memory it would need, while actually only
591        ever using a few hundred bytes of working memory and without too many
592        tests of the mode. This should make future maintenance and development
593        easier. A side effect of this work is that the limit of 200 on the nesting
594        depth of parentheses has been removed (though this was never a serious
595        limitation, I suspect). However, there is a downside: pcre_compile() now
596        runs more slowly than before (30% or more, depending on the pattern). I
597        hope this isn't a big issue. There is no effect on runtime performance.
599    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
600        newline (only possible for the last line of a file) and it was a
601        pattern that set a locale (followed by /Lsomething), pcretest crashed.
603    19. Added additional timing features to pcretest. (1) The -tm option now times
604        matching only, not compiling. (2) Both -t and -tm can be followed, as a
605        separate command line item, by a number that specifies the number of
606        repeats to use when timing. The default is 50000; this gives better
607        precision, but takes uncomfortably long for very large patterns.
609    20. Extended pcre_study() to be more clever in cases where a branch of a
610        subpattern has no definite first character. For example, (a*|b*)[cd] would
611        previously give no result from pcre_study(). Now it recognizes that the
612        first character must be a, b, c, or d.
614    21. There was an incorrect error "recursive call could loop indefinitely" if
615        a subpattern (or the entire pattern) that was being tested for matching an
616        empty string contained only one non-empty item after a nested subpattern.
617        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
618        incorrectly, because the \d was being skipped in the check.
620    22. The pcretest program now has a new pattern option /B and a command line
621        option -b, which is equivalent to adding /B to every pattern. This causes
622        it to show the compiled bytecode, without the additional information that
623        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
624        is the same as /B/I).
626    23. A new optimization is now able automatically to treat some sequences such
627        as a*b as a*+b. More specifically, if something simple (such as a character
628        or a simple class like \d) has an unlimited quantifier, and is followed by
629        something that cannot possibly match the quantified thing, the quantifier
630        is automatically "possessified".
632    24. A recursive reference to a subpattern whose number was greater than 39
633        went wrong under certain circumstances in UTF-8 mode. This bug could also
634        have affected the operation of pcre_study().
636    25. Realized that a little bit of performance could be had by replacing
637        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
639    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
641    27. Possessive quantifiers such as a++ were previously implemented by turning
642        them into atomic groups such as ($>a+). Now they have their own opcodes,
643        which improves performance. This includes the automatically created ones
644        from 23 above.
646    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
647        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
648        the first matched character to be a colon. This applied both to named and
649        numbered groups.
651    29. The ucpinternal.h header file was missing its idempotency #ifdef.
653    30. I was sent a "project" file called libpcre.a.dev which I understand makes
654        building PCRE on Windows easier, so I have included it in the distribution.
656    31. There is now a check in pcretest against a ridiculously large number being
657        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
658        loop, the loop is abandoned.
660    32. Forward references to subpatterns in conditions such as (?(2)...) where
661        subpattern 2 is defined later cause pcre_compile() to search forwards in
662        the pattern for the relevant set of parentheses. This search went wrong
663        when there were unescaped parentheses in a character class, parentheses
664        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
666    33. "Subroutine" calls and backreferences were previously restricted to
667        referencing subpatterns earlier in the regex. This restriction has now
668        been removed.
670    34. Added a number of extra features that are going to be in Perl 5.10. On the
671        whole, these are just syntactic alternatives for features that PCRE had
672        previously implemented using the Python syntax or my own invention. The
673        other formats are all retained for compatibility.
675        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
676            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
677            also .NET compatible.
679        (b) A recursion or subroutine call to a named group can now be defined as
680            (?&name) as well as (?P>name).
682        (c) A backreference to a named group can now be defined as \k<name> or
683            \k'name' as well as (?P=name). The new forms, as well as being in Perl
684            5.10, are also .NET compatible.
686        (d) A conditional reference to a named group can now use the syntax
687            (?(<name>) or (?('name') as well as (?(name).
689        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
690            groups (named and numbered) that are never evaluated inline, but can be
691            called as "subroutines" from elsewhere. In effect, the DEFINE condition
692            is always false. There may be only one alternative in such a group.
694        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
695            as the simple (?(R). The condition is true only if the most recent
696            recursion is that of the given number or name. It does not search out
697            through the entire recursion stack.
699        (g) The escape \gN or \g{N} has been added, where N is a positive or
700            negative number, specifying an absolute or relative reference.
702    35. Tidied to get rid of some further signed/unsigned compiler warnings and
703        some "unreachable code" warnings.
705    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
706        things, this adds five new scripts.
708    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
709        There were also incompatibilities regarding the handling of \Q..\E inside
710        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
711        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
713    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
714        matches an empty string, and forcibly breaks the loop. There were bugs in
715        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
716        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
717        separate and independent bugs (that affected different cases) have been
718        fixed.
720    39. Refactored the code to abolish the use of different opcodes for small
721        capturing bracket numbers. This is a tidy that I avoided doing when I
722        removed the limit on the number of capturing brackets for 3.5 back in 2001.
723        The new approach is not only tidier, it makes it possible to reduce the
724        memory needed to fix the previous bug (38).
726    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
727        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
728        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
729        mode.
731    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
732        report.
734    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
735        copy construction and assignment in the C++ wrapper.
737    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
738        couple of bugs that could have given wrong results in the "--newline=crlf"
739        case.
741    44. Added a number of casts and did some reorganization of signed/unsigned int
742        variables following suggestions from Dair Grant. Also renamed the variable
743        "this" as "item" because it is a C++ keyword.
745    45. Arranged for dftables to add
747          #include "pcre_internal.h"
749        to pcre_chartables.c because without it, gcc 4.x may remove the array
750        definition from the final binary if PCRE is built into a static library and
751        dead code stripping is activated.
753    46. For an unanchored pattern, if a match attempt fails at the start of a
754        newline sequence, and the newline setting is CRLF or ANY, and the next two
755        characters are CRLF, advance by two characters instead of one.
758  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
759  ---------------------  ---------------------

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