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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.
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing).
26    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
27        this is right because (?- can be followed by option settings as well as by
28        digits. I have, however, made the messages clearer.
31    Version 7.4 21-Sep-07
32    ---------------------
34    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
35        means that a class such as [\s] counted as "explicit reference to CR or
36        LF". That isn't really right - the whole point of the change was to try to
37        help when there was an actual mention of one of the two characters. So now
38        the change happens only if \r or \n (or a literal CR or LF) character is
39        encountered.
41    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
42        of both had grown to the point where there were only 3 bits left.
43        Fortunately, there was spare space in the data structure, and so I have
44        moved the internal flags into a new 16-bit field to free up more option
45        bits.
47    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
48        but did not set the internal JCHANGED flag - either of these is enough to
49        control the way the "get" function works - but the PCRE_INFO_JCHANGED
50        facility is supposed to tell if (?J) was ever used, so now (?J) at the
51        start sets both bits.
53    4.  Added options (at build time, compile time, exec time) to change \R from
54        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
56    5.  doc/pcresyntax.html was missing from the distribution.
58    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
59        compatibility, even though it is no longer used.
61    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
62        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
63        windows.h file is present (where different names are used). [This was
64        reversed later after testing - see 16 below.]
66    8.  Changed all #include <config.h> to #include "config.h". There were also
67        some further <pcre.h> cases that I changed to "pcre.h".
69    9.  When pcregrep was used with the --colour option, it missed the line ending
70        sequence off the lines that it output.
72    10. It was pointed out to me that arrays of string pointers cause lots of
73        relocations when a shared library is dynamically loaded. A technique of
74        using a single long string with a table of offsets can drastically reduce
75        these. I have refactored PCRE in four places to do this. The result is
76        dramatic:
78          Originally:                          290
79          After changing UCP table:            187
80          After changing error message table:   43
81          After changing table of "verbs"       36
82          After changing table of Posix names   22
84        Thanks to the folks working on Gregex for glib for this insight.
86    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
87        unicode-properties was also set.
89    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
91    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
92        checked only for CRLF.
94    14. Added casts to pcretest.c to avoid compiler warnings.
96    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
98    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
99        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
100        entirely. This removes changes made in 7 above.
102    17. The CMake files have been updated, and there is now more information about
103        building with CMake in the NON-UNIX-USE document.
106    Version 7.3 28-Aug-07
107    ---------------------
109     1. In the rejigging of the build system that eventually resulted in 7.1, the
110        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
111        brackets there is not right, since it causes compilers to look for an
112        installed pcre.h, not the version that is in the source that is being
113        compiled (which of course may be different). I have changed it back to:
115          #include "pcre.h"
117        I have a vague recollection that the change was concerned with compiling in
118        different directories, but in the new build system, that is taken care of
119        by the VPATH setting the Makefile.
121     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
122        when the subject happened to end in the byte 0x85 (e.g. if the last
123        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
124        characters but of course it shouldn't be taken as a newline when it is part
125        of another character. The bug was that, for an unlimited repeat of . in
126        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
127        characters when looking for a newline.
129     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
131     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
132        in debug output.
134     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
135        long printing in the pcrecpp unittest when running under MinGW.
137     6. ESC_K was left out of the EBCDIC table.
139     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
140        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
141        limit also applies to "virtual nesting" when a pattern is recursive, and in
142        this case 1000 isn't so big. I have been able to remove this limit at the
143        expense of backing off one optimization in certain circumstances. Normally,
144        when pcre_exec() would call its internal match() function recursively and
145        immediately return the result unconditionally, it uses a "tail recursion"
146        feature to save stack. However, when a subpattern that can match an empty
147        string has an unlimited repetition quantifier, it no longer makes this
148        optimization. That gives it a stack frame in which to save the data for
149        checking that an empty string has been matched. Previously this was taken
150        from the 1000-entry workspace that had been reserved. So now there is no
151        explicit limit, but more stack is used.
153     8. Applied Daniel's patches to solve problems with the import/export magic
154        syntax that is required for Windows, and which was going wrong for the
155        pcreposix and pcrecpp parts of the library. These were overlooked when this
156        problem was solved for the main library.
158     9. There were some crude static tests to avoid integer overflow when computing
159        the size of patterns that contain repeated groups with explicit upper
160        limits. As the maximum quantifier is 65535, the maximum group length was
161        set at 30,000 so that the product of these two numbers did not overflow a
162        32-bit integer. However, it turns out that people want to use groups that
163        are longer than 30,000 bytes (though not repeat them that many times).
164        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
165        made it possible to implement the integer overflow checks in a much more
166        dynamic way, which I have now done. The artificial limitation on group
167        length has been removed - we now have only the limit on the total length of
168        the compiled pattern, which depends on the LINK_SIZE setting.
170    10. Fixed a bug in the documentation for get/copy named substring when
171        duplicate names are permitted. If none of the named substrings are set, the
172        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
173        empty string.
175    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
176        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
177        because the ] is interpreted as the first data character and the
178        terminating ] is not found. PCRE has been made compatible with Perl in this
179        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
180        cause memory overwriting.
182    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
183        string has been matched (to stop an infinite loop). It was not recognizing
184        a conditional subpattern that could match an empty string if that
185        subpattern was within another subpattern. For example, it looped when
186        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
187        condition was not nested. This bug has been fixed.
189    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
190        past the start of the subject in the presence of bytes with the top bit
191        set, for example "\x8aBCD".
193    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
194        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
196    14. Optimized (?!) to (*FAIL).
198    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
199        This restricts code points to be within the range 0 to 0x10FFFF, excluding
200        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
201        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
202        does: it's just the validity check that is more restrictive.
204    16. Inserted checks for integer overflows during escape sequence (backslash)
205        processing, and also fixed erroneous offset values for syntax errors during
206        backslash processing.
208    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
209        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
211    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
212        caused an overrun.
214    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
215        something other than just ASCII characters) inside a group that had an
216        unlimited repeat caused a loop at compile time (while checking to see
217        whether the group could match an empty string).
219    20. Debugging a pattern containing \p or \P could cause a crash. For example,
220        [\P{Any}] did so. (Error in the code for printing property names.)
222    21. An orphan \E inside a character class could cause a crash.
224    22. A repeated capturing bracket such as (A)? could cause a wild memory
225        reference during compilation.
227    23. There are several functions in pcre_compile() that scan along a compiled
228        expression for various reasons (e.g. to see if it's fixed length for look
229        behind). There were bugs in these functions when a repeated \p or \P was
230        present in the pattern. These operators have additional parameters compared
231        with \d, etc, and these were not being taken into account when moving along
232        the compiled data. Specifically:
234        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
235            length.
237        (b) An item such as \pL+ within a repeated group could cause crashes or
238            loops.
240        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
241            "reference to non-existent subpattern" error.
243        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
245    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
246        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
248    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
250    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
251        character were causing crashes (broken optimization).
253    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
254        \p or \P) caused a compile-time loop.
256    28. More problems have arisen in unanchored patterns when CRLF is a valid line
257        break. For example, the unstudied pattern [\r\n]A does not match the string
258        "\r\nA" because change 7.0/46 below moves the current point on by two
259        characters after failing to match at the start. However, the pattern \nA
260        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
261        the same is true. There doesn't seem any very clean way out of this, but
262        what I have chosen to do makes the common cases work: PCRE now takes note
263        of whether there can be an explicit match for \r or \n anywhere in the
264        pattern, and if so, 7.0/46 no longer applies. As part of this change,
265        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
266        pattern has explicit CR or LF references.
268    29. Added (*CR) etc for changing newline setting at start of pattern.
271    Version 7.2 19-Jun-07
272    ---------------------
274     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
275        which is apparently normally available under Windows.
277     2. Re-jig the pcregrep tests with different newline settings in an attempt
278        to make them independent of the local environment's newline setting.
280     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
282     4. Some of the "internals" tests were previously cut out when the link size
283        was not 2, because the output contained actual offsets. The recent new
284        "Z" feature of pcretest means that these can be cut out, making the tests
285        usable with all link sizes.
287     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
288        stack recursion. This gives a massive performance boost under BSD, but just
289        a small improvement under Linux. However, it saves one field in the frame
290        in all cases.
292     6. Added more features from the forthcoming Perl 5.10:
294        (a) (?-n) (where n is a string of digits) is a relative subroutine or
295            recursion call. It refers to the nth most recently opened parentheses.
297        (b) (?+n) is also a relative subroutine call; it refers to the nth next
298            to be opened parentheses.
300        (c) Conditions that refer to capturing parentheses can be specified
301            relatively, for example, (?(-2)... or (?(+3)...
303        (d) \K resets the start of the current match so that everything before
304            is not part of it.
306        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
308        (f) \g{name} is another synonym - part of Perl 5.10's unification of
309            reference syntax.
311        (g) (?| introduces a group in which the numbering of parentheses in each
312            alternative starts with the same number.
314        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
316     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
319     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
320        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
321        for detecting groups that can match an empty string.
323     9. A pattern with a very large number of alternatives (more than several
324        hundred) was running out of internal workspace during the pre-compile
325        phase, where pcre_compile() figures out how much memory will be needed. A
326        bit of new cunning has reduced the workspace needed for groups with
327        alternatives. The 1000-alternative test pattern now uses 12 bytes of
328        workspace instead of running out of the 4096 that are available.
330    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
332    11. Applied patch from Google to remove an optimization that didn't quite work.
333        The report of the bug said:
335          pcrecpp::RE("a*").FullMatch("aaa") matches, while
336          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
337          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
339    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
340        it matched the wrong number of bytes.
343    Version 7.1 24-Apr-07
344    ---------------------
346     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
347        that is more "standard", making use of automake and other Autotools. There
348        is some re-arrangement of the files and adjustment of comments consequent
349        on this.
351     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
352        for recursive directory scanning broke on some systems because the files
353        are not scanned in any specific order and on different systems the order
354        was different. A call to "sort" has been inserted into RunGrepTest for the
355        approprate test as a short-term fix. In the longer term there may be an
356        alternative.
358     3. I had an email from Eric Raymond about problems translating some of PCRE's
359        man pages to HTML (despite the fact that I distribute HTML pages, some
360        people do their own conversions for various reasons). The problems
361        concerned the use of low-level troff macros .br and .in. I have therefore
362        removed all such uses from the man pages (some were redundant, some could
363        be replaced by .nf/.fi pairs). The 132html script that I use to generate
364        HTML has been updated to handle .nf/.fi and to complain if it encounters
365        .br or .in.
367     4. Updated comments in configure.ac that get placed in config.h.in and also
368        arranged for config.h to be included in the distribution, with the name
369        config.h.generic, for the benefit of those who have to compile without
370        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
372     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
373        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
374        makevp.bat for the current PCRE, using the additional files
375        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
377     6. A Windows user reported a minor discrepancy with test 2, which turned out
378        to be caused by a trailing space on an input line that had got lost in his
379        copy. The trailing space was an accident, so I've just removed it.
381     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
382        that is needed.
384     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
385        as "const" (a) because they are and (b) because it helps the PHP
386        maintainers who have recently made a script to detect big data structures
387        in the php code that should be moved to the .rodata section. I remembered
388        to update Builducptable as well, so it won't revert if ucptable.h is ever
389        re-created.
391     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
392        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
393        order to be able to cut out the UTF-8 tables in the latter when UTF-8
394        support is not required. This saves 1.5-2K of code, which is important in
395        some applications.
397        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
398        so as not to refer to the tables, even though these functions will never be
399        called when UTF-8 support is disabled. Otherwise there are problems with a
400        shared library.
402    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
404        (a) It was defining its arguments as char * instead of void *.
406        (b) It was assuming that all moves were upwards in memory; this was true
407            a long time ago when I wrote it, but is no longer the case.
409        The emulated memove() is provided for those environments that have neither
410        memmove() nor bcopy(). I didn't think anyone used it these days, but that
411        is clearly not the case, as these two bugs were recently reported.
413    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
414        and Detrail to create the HTML documentation, the .txt form of the man
415        pages, and it removes trailing spaces from listed files. It also creates
416        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
417        case, it wraps all the #defines with #ifndefs. This script should be run
418        before "make dist".
420    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
421        with Unicode property support.
423        (a) For a maximizing quantifier, if the two different cases of the
424            character were of different lengths in their UTF-8 codings (there are
425            some cases like this - I found 11), and the matching function had to
426            back up over a mixture of the two cases, it incorrectly assumed they
427            were both the same length.
429        (b) When PCRE was configured to use the heap rather than the stack for
430            recursion during matching, it was not correctly preserving the data for
431            the other case of a UTF-8 character when checking ahead for a match
432            while processing a minimizing repeat. If the check also involved
433            matching a wide character, but failed, corruption could cause an
434            erroneous result when trying to check for a repeat of the original
435            character.
437    13. Some tidying changes to the testing mechanism:
439        (a) The RunTest script now detects the internal link size and whether there
440            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
441            values substituted by "configure". (The RunGrepTest script already did
442            this for UTF-8.) The configure.ac script no longer substitutes the
443            relevant variables.
445        (b) The debugging options /B and /D in pcretest show the compiled bytecode
446            with length and offset values. This means that the output is different
447            for different internal link sizes. Test 2 is skipped for link sizes
448            other than 2 because of this, bypassing the problem. Unfortunately,
449            there was also a test in test 3 (the locale tests) that used /B and
450            failed for link sizes other than 2. Rather than cut the whole test out,
451            I have added a new /Z option to pcretest that replaces the length and
452            offset values with spaces. This is now used to make test 3 independent
453            of link size. (Test 2 will be tidied up later.)
455    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
456        segmentation fault instead of returning the appropriate error message.
458    15. In multiline mode when the newline sequence was set to "any", the pattern
459        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
460        This doesn't seem right; it now treats the CRLF combination as the line
461        ending, and so does not match in that case. It's only a pattern such as ^$
462        that would hit this one: something like ^ABC$ would have failed after \r
463        and then tried again after \r\n.
465    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
466        in an attempt to make files that differ only in their line terminators
467        compare equal. This works on Linux.
469    17. Under certain error circumstances pcregrep might try to free random memory
470        as it exited. This is now fixed, thanks to valgrind.
472    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
473        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
474        was because its rules for how to advance for /g after matching an empty
475        string at the end of a line did not allow for this case. They now check for
476        it specially.
478    20. pcretest is supposed to handle patterns and data of any length, by
479        extending its buffers when necessary. It was getting this wrong when the
480        buffer for a data line had to be extended.
482    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
483        CRLF as a newline sequence.
485    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
486        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
487        I have nevertheless tidied it up.
489    23. Added some casts to kill warnings from HP-UX ia64 compiler.
491    24. Added a man page for pcre-config.
494    Version 7.0 19-Dec-06
495    ---------------------
497     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
498        moving to gcc 4.1.1.
500     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
501        sys/time.h, which is documented as needed for this function. It doesn't
502        seem to matter on Linux, but it showed up on some releases of OS X.
504     3. It seems that there are systems where bytes whose values are greater than
505        127 match isprint() in the "C" locale. The "C" locale should be the
506        default when a C program starts up. In most systems, only ASCII printing
507        characters match isprint(). This difference caused the output from pcretest
508        to vary, making some of the tests fail. I have changed pcretest so that:
510        (a) When it is outputting text in the compiled version of a pattern, bytes
511            other than 32-126 are always shown as hex escapes.
513        (b) When it is outputting text that is a matched part of a subject string,
514            it does the same, unless a different locale has been set for the match
515            (using the /L modifier). In this case, it uses isprint() to decide.
517     4. Fixed a major bug that caused incorrect computation of the amount of memory
518        required for a compiled pattern when options that changed within the
519        pattern affected the logic of the preliminary scan that determines the
520        length. The relevant options are -x, and -i in UTF-8 mode. The result was
521        that the computed length was too small. The symptoms of this bug were
522        either the PCRE error "internal error: code overflow" from pcre_compile(),
523        or a glibc crash with a message such as "pcretest: free(): invalid next
524        size (fast)". Examples of patterns that provoked this bug (shown in
525        pcretest format) are:
527          /(?-x: )/x
528          /(?x)(?-x: \s*#\s*)/
529          /((?i)[\x{c0}])/8
530          /(?i:[\x{c0}])/8
532        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
533        is now done differently.
535     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
536        wrapper classes; (b) implement a new function in the C++ scanner that is
537        more efficient than the old way of doing things because it avoids levels of
538        recursion in the regex matching; (c) add a paragraph to the documentation
539        for the FullMatch() function.
541     6. The escape sequence \n was being treated as whatever was defined as
542        "newline". Not only was this contrary to the documentation, which states
543        that \n is character 10 (hex 0A), but it also went horribly wrong when
544        "newline" was defined as CRLF. This has been fixed.
546     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
547        was being set to -1 for the "end of line" case (supposedly a value that no
548        character can have). Though this value is never used (the check for end of
549        line is "zero bytes in current character"), it caused compiler complaints.
550        I've changed it to 0xffffffff.
552     8. In pcre_version.c, the version string was being built by a sequence of
553        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
554        string (as it is for production releases) called a macro with an empty
555        argument. The C standard says the result of this is undefined. The gcc
556        compiler treats it as an empty string (which was what was wanted) but it is
557        reported that Visual C gives an error. The source has been hacked around to
558        avoid this problem.
560     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
561        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
562        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
563        of them did).
565    10. Originally, pcretest opened its input and output without "b"; then I was
566        told that "b" was needed in some environments, so it was added for release
567        5.0 to both the input and output. (It makes no difference on Unix-like
568        systems.) Later I was told that it is wrong for the input on Windows. I've
569        now abstracted the modes into two macros, to make it easier to fiddle with
570        them, and removed "b" from the input mode under Windows.
572    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
574    12. Added -help and --help to pcretest as an official way of being reminded
575        of the options.
577    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
578        and pcrecpp.cc because they annoy compilers at high warning levels.
580    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
582    15. Fixed an occurrence of == in configure.ac that should have been = (shell
583        scripts are not C programs :-) and which was not noticed because it works
584        on Linux.
586    16. pcretest is supposed to handle any length of pattern and data line (as one
587        line or as a continued sequence of lines) by extending its input buffer if
588        necessary. This feature was broken for very long pattern lines, leading to
589        a string of junk being passed to pcre_compile() if the pattern was longer
590        than about 50K.
592    17. I have done a major re-factoring of the way pcre_compile() computes the
593        amount of memory needed for a compiled pattern. Previously, there was code
594        that made a preliminary scan of the pattern in order to do this. That was
595        OK when PCRE was new, but as the facilities have expanded, it has become
596        harder and harder to keep it in step with the real compile phase, and there
597        have been a number of bugs (see for example, 4 above). I have now found a
598        cunning way of running the real compile function in a "fake" mode that
599        enables it to compute how much memory it would need, while actually only
600        ever using a few hundred bytes of working memory and without too many
601        tests of the mode. This should make future maintenance and development
602        easier. A side effect of this work is that the limit of 200 on the nesting
603        depth of parentheses has been removed (though this was never a serious
604        limitation, I suspect). However, there is a downside: pcre_compile() now
605        runs more slowly than before (30% or more, depending on the pattern). I
606        hope this isn't a big issue. There is no effect on runtime performance.
608    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
609        newline (only possible for the last line of a file) and it was a
610        pattern that set a locale (followed by /Lsomething), pcretest crashed.
612    19. Added additional timing features to pcretest. (1) The -tm option now times
613        matching only, not compiling. (2) Both -t and -tm can be followed, as a
614        separate command line item, by a number that specifies the number of
615        repeats to use when timing. The default is 50000; this gives better
616        precision, but takes uncomfortably long for very large patterns.
618    20. Extended pcre_study() to be more clever in cases where a branch of a
619        subpattern has no definite first character. For example, (a*|b*)[cd] would
620        previously give no result from pcre_study(). Now it recognizes that the
621        first character must be a, b, c, or d.
623    21. There was an incorrect error "recursive call could loop indefinitely" if
624        a subpattern (or the entire pattern) that was being tested for matching an
625        empty string contained only one non-empty item after a nested subpattern.
626        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
627        incorrectly, because the \d was being skipped in the check.
629    22. The pcretest program now has a new pattern option /B and a command line
630        option -b, which is equivalent to adding /B to every pattern. This causes
631        it to show the compiled bytecode, without the additional information that
632        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
633        is the same as /B/I).
635    23. A new optimization is now able automatically to treat some sequences such
636        as a*b as a*+b. More specifically, if something simple (such as a character
637        or a simple class like \d) has an unlimited quantifier, and is followed by
638        something that cannot possibly match the quantified thing, the quantifier
639        is automatically "possessified".
641    24. A recursive reference to a subpattern whose number was greater than 39
642        went wrong under certain circumstances in UTF-8 mode. This bug could also
643        have affected the operation of pcre_study().
645    25. Realized that a little bit of performance could be had by replacing
646        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
648    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
650    27. Possessive quantifiers such as a++ were previously implemented by turning
651        them into atomic groups such as ($>a+). Now they have their own opcodes,
652        which improves performance. This includes the automatically created ones
653        from 23 above.
655    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
656        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
657        the first matched character to be a colon. This applied both to named and
658        numbered groups.
660    29. The ucpinternal.h header file was missing its idempotency #ifdef.
662    30. I was sent a "project" file called libpcre.a.dev which I understand makes
663        building PCRE on Windows easier, so I have included it in the distribution.
665    31. There is now a check in pcretest against a ridiculously large number being
666        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
667        loop, the loop is abandoned.
669    32. Forward references to subpatterns in conditions such as (?(2)...) where
670        subpattern 2 is defined later cause pcre_compile() to search forwards in
671        the pattern for the relevant set of parentheses. This search went wrong
672        when there were unescaped parentheses in a character class, parentheses
673        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
675    33. "Subroutine" calls and backreferences were previously restricted to
676        referencing subpatterns earlier in the regex. This restriction has now
677        been removed.
679    34. Added a number of extra features that are going to be in Perl 5.10. On the
680        whole, these are just syntactic alternatives for features that PCRE had
681        previously implemented using the Python syntax or my own invention. The
682        other formats are all retained for compatibility.
684        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
685            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
686            also .NET compatible.
688        (b) A recursion or subroutine call to a named group can now be defined as
689            (?&name) as well as (?P>name).
691        (c) A backreference to a named group can now be defined as \k<name> or
692            \k'name' as well as (?P=name). The new forms, as well as being in Perl
693            5.10, are also .NET compatible.
695        (d) A conditional reference to a named group can now use the syntax
696            (?(<name>) or (?('name') as well as (?(name).
698        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
699            groups (named and numbered) that are never evaluated inline, but can be
700            called as "subroutines" from elsewhere. In effect, the DEFINE condition
701            is always false. There may be only one alternative in such a group.
703        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
704            as the simple (?(R). The condition is true only if the most recent
705            recursion is that of the given number or name. It does not search out
706            through the entire recursion stack.
708        (g) The escape \gN or \g{N} has been added, where N is a positive or
709            negative number, specifying an absolute or relative reference.
711    35. Tidied to get rid of some further signed/unsigned compiler warnings and
712        some "unreachable code" warnings.
714    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
715        things, this adds five new scripts.
717    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
718        There were also incompatibilities regarding the handling of \Q..\E inside
719        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
720        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
722    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
723        matches an empty string, and forcibly breaks the loop. There were bugs in
724        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
725        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
726        separate and independent bugs (that affected different cases) have been
727        fixed.
729    39. Refactored the code to abolish the use of different opcodes for small
730        capturing bracket numbers. This is a tidy that I avoided doing when I
731        removed the limit on the number of capturing brackets for 3.5 back in 2001.
732        The new approach is not only tidier, it makes it possible to reduce the
733        memory needed to fix the previous bug (38).
735    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
736        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
737        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
738        mode.
740    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
741        report.
743    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
744        copy construction and assignment in the C++ wrapper.
746    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
747        couple of bugs that could have given wrong results in the "--newline=crlf"
748        case.
750    44. Added a number of casts and did some reorganization of signed/unsigned int
751        variables following suggestions from Dair Grant. Also renamed the variable
752        "this" as "item" because it is a C++ keyword.
754    45. Arranged for dftables to add
756          #include "pcre_internal.h"
758        to pcre_chartables.c because without it, gcc 4.x may remove the array
759        definition from the final binary if PCRE is built into a static library and
760        dead code stripping is activated.
762    46. For an unanchored pattern, if a match attempt fails at the start of a
763        newline sequence, and the newline setting is CRLF or ANY, and the next two
764        characters are CRLF, advance by two characters instead of one.
767  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
768  ---------------------  ---------------------

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