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revision 83 by nigel, Sat Feb 24 21:41:06 2007 UTC revision 275 by ph10, Wed Nov 21 15:35:09 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.
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). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
46    Version 7.4 21-Sep-07
47    ---------------------
49    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
50        means that a class such as [\s] counted as "explicit reference to CR or
51        LF". That isn't really right - the whole point of the change was to try to
52        help when there was an actual mention of one of the two characters. So now
53        the change happens only if \r or \n (or a literal CR or LF) character is
54        encountered.
56    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
57        of both had grown to the point where there were only 3 bits left.
58        Fortunately, there was spare space in the data structure, and so I have
59        moved the internal flags into a new 16-bit field to free up more option
60        bits.
62    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
63        but did not set the internal JCHANGED flag - either of these is enough to
64        control the way the "get" function works - but the PCRE_INFO_JCHANGED
65        facility is supposed to tell if (?J) was ever used, so now (?J) at the
66        start sets both bits.
68    4.  Added options (at build time, compile time, exec time) to change \R from
69        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
71    5.  doc/pcresyntax.html was missing from the distribution.
73    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
74        compatibility, even though it is no longer used.
76    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
77        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
78        windows.h file is present (where different names are used). [This was
79        reversed later after testing - see 16 below.]
81    8.  Changed all #include <config.h> to #include "config.h". There were also
82        some further <pcre.h> cases that I changed to "pcre.h".
84    9.  When pcregrep was used with the --colour option, it missed the line ending
85        sequence off the lines that it output.
87    10. It was pointed out to me that arrays of string pointers cause lots of
88        relocations when a shared library is dynamically loaded. A technique of
89        using a single long string with a table of offsets can drastically reduce
90        these. I have refactored PCRE in four places to do this. The result is
91        dramatic:
93          Originally:                          290
94          After changing UCP table:            187
95          After changing error message table:   43
96          After changing table of "verbs"       36
97          After changing table of Posix names   22
99        Thanks to the folks working on Gregex for glib for this insight.
101    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
102        unicode-properties was also set.
104    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
106    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
107        checked only for CRLF.
109    14. Added casts to pcretest.c to avoid compiler warnings.
111    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
113    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
114        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
115        entirely. This removes changes made in 7 above.
117    17. The CMake files have been updated, and there is now more information about
118        building with CMake in the NON-UNIX-USE document.
121    Version 7.3 28-Aug-07
122    ---------------------
124     1. In the rejigging of the build system that eventually resulted in 7.1, the
125        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
126        brackets there is not right, since it causes compilers to look for an
127        installed pcre.h, not the version that is in the source that is being
128        compiled (which of course may be different). I have changed it back to:
130          #include "pcre.h"
132        I have a vague recollection that the change was concerned with compiling in
133        different directories, but in the new build system, that is taken care of
134        by the VPATH setting the Makefile.
136     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
137        when the subject happened to end in the byte 0x85 (e.g. if the last
138        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
139        characters but of course it shouldn't be taken as a newline when it is part
140        of another character. The bug was that, for an unlimited repeat of . in
141        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
142        characters when looking for a newline.
144     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
146     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
147        in debug output.
149     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
150        long printing in the pcrecpp unittest when running under MinGW.
152     6. ESC_K was left out of the EBCDIC table.
154     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
155        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
156        limit also applies to "virtual nesting" when a pattern is recursive, and in
157        this case 1000 isn't so big. I have been able to remove this limit at the
158        expense of backing off one optimization in certain circumstances. Normally,
159        when pcre_exec() would call its internal match() function recursively and
160        immediately return the result unconditionally, it uses a "tail recursion"
161        feature to save stack. However, when a subpattern that can match an empty
162        string has an unlimited repetition quantifier, it no longer makes this
163        optimization. That gives it a stack frame in which to save the data for
164        checking that an empty string has been matched. Previously this was taken
165        from the 1000-entry workspace that had been reserved. So now there is no
166        explicit limit, but more stack is used.
168     8. Applied Daniel's patches to solve problems with the import/export magic
169        syntax that is required for Windows, and which was going wrong for the
170        pcreposix and pcrecpp parts of the library. These were overlooked when this
171        problem was solved for the main library.
173     9. There were some crude static tests to avoid integer overflow when computing
174        the size of patterns that contain repeated groups with explicit upper
175        limits. As the maximum quantifier is 65535, the maximum group length was
176        set at 30,000 so that the product of these two numbers did not overflow a
177        32-bit integer. However, it turns out that people want to use groups that
178        are longer than 30,000 bytes (though not repeat them that many times).
179        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
180        made it possible to implement the integer overflow checks in a much more
181        dynamic way, which I have now done. The artificial limitation on group
182        length has been removed - we now have only the limit on the total length of
183        the compiled pattern, which depends on the LINK_SIZE setting.
185    10. Fixed a bug in the documentation for get/copy named substring when
186        duplicate names are permitted. If none of the named substrings are set, the
187        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
188        empty string.
190    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
191        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
192        because the ] is interpreted as the first data character and the
193        terminating ] is not found. PCRE has been made compatible with Perl in this
194        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
195        cause memory overwriting.
197    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
198        string has been matched (to stop an infinite loop). It was not recognizing
199        a conditional subpattern that could match an empty string if that
200        subpattern was within another subpattern. For example, it looped when
201        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
202        condition was not nested. This bug has been fixed.
204    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
205        past the start of the subject in the presence of bytes with the top bit
206        set, for example "\x8aBCD".
208    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
209        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
211    14. Optimized (?!) to (*FAIL).
213    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
214        This restricts code points to be within the range 0 to 0x10FFFF, excluding
215        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
216        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
217        does: it's just the validity check that is more restrictive.
219    16. Inserted checks for integer overflows during escape sequence (backslash)
220        processing, and also fixed erroneous offset values for syntax errors during
221        backslash processing.
223    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
224        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
226    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
227        caused an overrun.
229    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
230        something other than just ASCII characters) inside a group that had an
231        unlimited repeat caused a loop at compile time (while checking to see
232        whether the group could match an empty string).
234    20. Debugging a pattern containing \p or \P could cause a crash. For example,
235        [\P{Any}] did so. (Error in the code for printing property names.)
237    21. An orphan \E inside a character class could cause a crash.
239    22. A repeated capturing bracket such as (A)? could cause a wild memory
240        reference during compilation.
242    23. There are several functions in pcre_compile() that scan along a compiled
243        expression for various reasons (e.g. to see if it's fixed length for look
244        behind). There were bugs in these functions when a repeated \p or \P was
245        present in the pattern. These operators have additional parameters compared
246        with \d, etc, and these were not being taken into account when moving along
247        the compiled data. Specifically:
249        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
250            length.
252        (b) An item such as \pL+ within a repeated group could cause crashes or
253            loops.
255        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
256            "reference to non-existent subpattern" error.
258        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
260    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
261        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
263    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
265    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
266        character were causing crashes (broken optimization).
268    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
269        \p or \P) caused a compile-time loop.
271    28. More problems have arisen in unanchored patterns when CRLF is a valid line
272        break. For example, the unstudied pattern [\r\n]A does not match the string
273        "\r\nA" because change 7.0/46 below moves the current point on by two
274        characters after failing to match at the start. However, the pattern \nA
275        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
276        the same is true. There doesn't seem any very clean way out of this, but
277        what I have chosen to do makes the common cases work: PCRE now takes note
278        of whether there can be an explicit match for \r or \n anywhere in the
279        pattern, and if so, 7.0/46 no longer applies. As part of this change,
280        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
281        pattern has explicit CR or LF references.
283    29. Added (*CR) etc for changing newline setting at start of pattern.
286    Version 7.2 19-Jun-07
287    ---------------------
289     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
290        which is apparently normally available under Windows.
292     2. Re-jig the pcregrep tests with different newline settings in an attempt
293        to make them independent of the local environment's newline setting.
295     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
297     4. Some of the "internals" tests were previously cut out when the link size
298        was not 2, because the output contained actual offsets. The recent new
299        "Z" feature of pcretest means that these can be cut out, making the tests
300        usable with all link sizes.
302     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
303        stack recursion. This gives a massive performance boost under BSD, but just
304        a small improvement under Linux. However, it saves one field in the frame
305        in all cases.
307     6. Added more features from the forthcoming Perl 5.10:
309        (a) (?-n) (where n is a string of digits) is a relative subroutine or
310            recursion call. It refers to the nth most recently opened parentheses.
312        (b) (?+n) is also a relative subroutine call; it refers to the nth next
313            to be opened parentheses.
315        (c) Conditions that refer to capturing parentheses can be specified
316            relatively, for example, (?(-2)... or (?(+3)...
318        (d) \K resets the start of the current match so that everything before
319            is not part of it.
321        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
323        (f) \g{name} is another synonym - part of Perl 5.10's unification of
324            reference syntax.
326        (g) (?| introduces a group in which the numbering of parentheses in each
327            alternative starts with the same number.
329        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
331     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
334     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
335        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
336        for detecting groups that can match an empty string.
338     9. A pattern with a very large number of alternatives (more than several
339        hundred) was running out of internal workspace during the pre-compile
340        phase, where pcre_compile() figures out how much memory will be needed. A
341        bit of new cunning has reduced the workspace needed for groups with
342        alternatives. The 1000-alternative test pattern now uses 12 bytes of
343        workspace instead of running out of the 4096 that are available.
345    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
347    11. Applied patch from Google to remove an optimization that didn't quite work.
348        The report of the bug said:
350          pcrecpp::RE("a*").FullMatch("aaa") matches, while
351          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
352          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
354    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
355        it matched the wrong number of bytes.
358    Version 7.1 24-Apr-07
359    ---------------------
361     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
362        that is more "standard", making use of automake and other Autotools. There
363        is some re-arrangement of the files and adjustment of comments consequent
364        on this.
366     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
367        for recursive directory scanning broke on some systems because the files
368        are not scanned in any specific order and on different systems the order
369        was different. A call to "sort" has been inserted into RunGrepTest for the
370        approprate test as a short-term fix. In the longer term there may be an
371        alternative.
373     3. I had an email from Eric Raymond about problems translating some of PCRE's
374        man pages to HTML (despite the fact that I distribute HTML pages, some
375        people do their own conversions for various reasons). The problems
376        concerned the use of low-level troff macros .br and .in. I have therefore
377        removed all such uses from the man pages (some were redundant, some could
378        be replaced by .nf/.fi pairs). The 132html script that I use to generate
379        HTML has been updated to handle .nf/.fi and to complain if it encounters
380        .br or .in.
382     4. Updated comments in configure.ac that get placed in config.h.in and also
383        arranged for config.h to be included in the distribution, with the name
384        config.h.generic, for the benefit of those who have to compile without
385        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
387     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
388        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
389        makevp.bat for the current PCRE, using the additional files
390        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
392     6. A Windows user reported a minor discrepancy with test 2, which turned out
393        to be caused by a trailing space on an input line that had got lost in his
394        copy. The trailing space was an accident, so I've just removed it.
396     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
397        that is needed.
399     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
400        as "const" (a) because they are and (b) because it helps the PHP
401        maintainers who have recently made a script to detect big data structures
402        in the php code that should be moved to the .rodata section. I remembered
403        to update Builducptable as well, so it won't revert if ucptable.h is ever
404        re-created.
406     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
407        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
408        order to be able to cut out the UTF-8 tables in the latter when UTF-8
409        support is not required. This saves 1.5-2K of code, which is important in
410        some applications.
412        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
413        so as not to refer to the tables, even though these functions will never be
414        called when UTF-8 support is disabled. Otherwise there are problems with a
415        shared library.
417    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
419        (a) It was defining its arguments as char * instead of void *.
421        (b) It was assuming that all moves were upwards in memory; this was true
422            a long time ago when I wrote it, but is no longer the case.
424        The emulated memove() is provided for those environments that have neither
425        memmove() nor bcopy(). I didn't think anyone used it these days, but that
426        is clearly not the case, as these two bugs were recently reported.
428    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
429        and Detrail to create the HTML documentation, the .txt form of the man
430        pages, and it removes trailing spaces from listed files. It also creates
431        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
432        case, it wraps all the #defines with #ifndefs. This script should be run
433        before "make dist".
435    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
436        with Unicode property support.
438        (a) For a maximizing quantifier, if the two different cases of the
439            character were of different lengths in their UTF-8 codings (there are
440            some cases like this - I found 11), and the matching function had to
441            back up over a mixture of the two cases, it incorrectly assumed they
442            were both the same length.
444        (b) When PCRE was configured to use the heap rather than the stack for
445            recursion during matching, it was not correctly preserving the data for
446            the other case of a UTF-8 character when checking ahead for a match
447            while processing a minimizing repeat. If the check also involved
448            matching a wide character, but failed, corruption could cause an
449            erroneous result when trying to check for a repeat of the original
450            character.
452    13. Some tidying changes to the testing mechanism:
454        (a) The RunTest script now detects the internal link size and whether there
455            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
456            values substituted by "configure". (The RunGrepTest script already did
457            this for UTF-8.) The configure.ac script no longer substitutes the
458            relevant variables.
460        (b) The debugging options /B and /D in pcretest show the compiled bytecode
461            with length and offset values. This means that the output is different
462            for different internal link sizes. Test 2 is skipped for link sizes
463            other than 2 because of this, bypassing the problem. Unfortunately,
464            there was also a test in test 3 (the locale tests) that used /B and
465            failed for link sizes other than 2. Rather than cut the whole test out,
466            I have added a new /Z option to pcretest that replaces the length and
467            offset values with spaces. This is now used to make test 3 independent
468            of link size. (Test 2 will be tidied up later.)
470    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
471        segmentation fault instead of returning the appropriate error message.
473    15. In multiline mode when the newline sequence was set to "any", the pattern
474        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
475        This doesn't seem right; it now treats the CRLF combination as the line
476        ending, and so does not match in that case. It's only a pattern such as ^$
477        that would hit this one: something like ^ABC$ would have failed after \r
478        and then tried again after \r\n.
480    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
481        in an attempt to make files that differ only in their line terminators
482        compare equal. This works on Linux.
484    17. Under certain error circumstances pcregrep might try to free random memory
485        as it exited. This is now fixed, thanks to valgrind.
487    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
488        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
489        was because its rules for how to advance for /g after matching an empty
490        string at the end of a line did not allow for this case. They now check for
491        it specially.
493    20. pcretest is supposed to handle patterns and data of any length, by
494        extending its buffers when necessary. It was getting this wrong when the
495        buffer for a data line had to be extended.
497    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
498        CRLF as a newline sequence.
500    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
501        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
502        I have nevertheless tidied it up.
504    23. Added some casts to kill warnings from HP-UX ia64 compiler.
506    24. Added a man page for pcre-config.
509    Version 7.0 19-Dec-06
510    ---------------------
512     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
513        moving to gcc 4.1.1.
515     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
516        sys/time.h, which is documented as needed for this function. It doesn't
517        seem to matter on Linux, but it showed up on some releases of OS X.
519     3. It seems that there are systems where bytes whose values are greater than
520        127 match isprint() in the "C" locale. The "C" locale should be the
521        default when a C program starts up. In most systems, only ASCII printing
522        characters match isprint(). This difference caused the output from pcretest
523        to vary, making some of the tests fail. I have changed pcretest so that:
525        (a) When it is outputting text in the compiled version of a pattern, bytes
526            other than 32-126 are always shown as hex escapes.
528        (b) When it is outputting text that is a matched part of a subject string,
529            it does the same, unless a different locale has been set for the match
530            (using the /L modifier). In this case, it uses isprint() to decide.
532     4. Fixed a major bug that caused incorrect computation of the amount of memory
533        required for a compiled pattern when options that changed within the
534        pattern affected the logic of the preliminary scan that determines the
535        length. The relevant options are -x, and -i in UTF-8 mode. The result was
536        that the computed length was too small. The symptoms of this bug were
537        either the PCRE error "internal error: code overflow" from pcre_compile(),
538        or a glibc crash with a message such as "pcretest: free(): invalid next
539        size (fast)". Examples of patterns that provoked this bug (shown in
540        pcretest format) are:
542          /(?-x: )/x
543          /(?x)(?-x: \s*#\s*)/
544          /((?i)[\x{c0}])/8
545          /(?i:[\x{c0}])/8
547        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
548        is now done differently.
550     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
551        wrapper classes; (b) implement a new function in the C++ scanner that is
552        more efficient than the old way of doing things because it avoids levels of
553        recursion in the regex matching; (c) add a paragraph to the documentation
554        for the FullMatch() function.
556     6. The escape sequence \n was being treated as whatever was defined as
557        "newline". Not only was this contrary to the documentation, which states
558        that \n is character 10 (hex 0A), but it also went horribly wrong when
559        "newline" was defined as CRLF. This has been fixed.
561     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
562        was being set to -1 for the "end of line" case (supposedly a value that no
563        character can have). Though this value is never used (the check for end of
564        line is "zero bytes in current character"), it caused compiler complaints.
565        I've changed it to 0xffffffff.
567     8. In pcre_version.c, the version string was being built by a sequence of
568        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
569        string (as it is for production releases) called a macro with an empty
570        argument. The C standard says the result of this is undefined. The gcc
571        compiler treats it as an empty string (which was what was wanted) but it is
572        reported that Visual C gives an error. The source has been hacked around to
573        avoid this problem.
575     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
576        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
577        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
578        of them did).
580    10. Originally, pcretest opened its input and output without "b"; then I was
581        told that "b" was needed in some environments, so it was added for release
582        5.0 to both the input and output. (It makes no difference on Unix-like
583        systems.) Later I was told that it is wrong for the input on Windows. I've
584        now abstracted the modes into two macros, to make it easier to fiddle with
585        them, and removed "b" from the input mode under Windows.
587    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
589    12. Added -help and --help to pcretest as an official way of being reminded
590        of the options.
592    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
593        and pcrecpp.cc because they annoy compilers at high warning levels.
595    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
597    15. Fixed an occurrence of == in configure.ac that should have been = (shell
598        scripts are not C programs :-) and which was not noticed because it works
599        on Linux.
601    16. pcretest is supposed to handle any length of pattern and data line (as one
602        line or as a continued sequence of lines) by extending its input buffer if
603        necessary. This feature was broken for very long pattern lines, leading to
604        a string of junk being passed to pcre_compile() if the pattern was longer
605        than about 50K.
607    17. I have done a major re-factoring of the way pcre_compile() computes the
608        amount of memory needed for a compiled pattern. Previously, there was code
609        that made a preliminary scan of the pattern in order to do this. That was
610        OK when PCRE was new, but as the facilities have expanded, it has become
611        harder and harder to keep it in step with the real compile phase, and there
612        have been a number of bugs (see for example, 4 above). I have now found a
613        cunning way of running the real compile function in a "fake" mode that
614        enables it to compute how much memory it would need, while actually only
615        ever using a few hundred bytes of working memory and without too many
616        tests of the mode. This should make future maintenance and development
617        easier. A side effect of this work is that the limit of 200 on the nesting
618        depth of parentheses has been removed (though this was never a serious
619        limitation, I suspect). However, there is a downside: pcre_compile() now
620        runs more slowly than before (30% or more, depending on the pattern). I
621        hope this isn't a big issue. There is no effect on runtime performance.
623    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
624        newline (only possible for the last line of a file) and it was a
625        pattern that set a locale (followed by /Lsomething), pcretest crashed.
627    19. Added additional timing features to pcretest. (1) The -tm option now times
628        matching only, not compiling. (2) Both -t and -tm can be followed, as a
629        separate command line item, by a number that specifies the number of
630        repeats to use when timing. The default is 50000; this gives better
631        precision, but takes uncomfortably long for very large patterns.
633    20. Extended pcre_study() to be more clever in cases where a branch of a
634        subpattern has no definite first character. For example, (a*|b*)[cd] would
635        previously give no result from pcre_study(). Now it recognizes that the
636        first character must be a, b, c, or d.
638    21. There was an incorrect error "recursive call could loop indefinitely" if
639        a subpattern (or the entire pattern) that was being tested for matching an
640        empty string contained only one non-empty item after a nested subpattern.
641        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
642        incorrectly, because the \d was being skipped in the check.
644    22. The pcretest program now has a new pattern option /B and a command line
645        option -b, which is equivalent to adding /B to every pattern. This causes
646        it to show the compiled bytecode, without the additional information that
647        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
648        is the same as /B/I).
650    23. A new optimization is now able automatically to treat some sequences such
651        as a*b as a*+b. More specifically, if something simple (such as a character
652        or a simple class like \d) has an unlimited quantifier, and is followed by
653        something that cannot possibly match the quantified thing, the quantifier
654        is automatically "possessified".
656    24. A recursive reference to a subpattern whose number was greater than 39
657        went wrong under certain circumstances in UTF-8 mode. This bug could also
658        have affected the operation of pcre_study().
660    25. Realized that a little bit of performance could be had by replacing
661        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
663    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
665    27. Possessive quantifiers such as a++ were previously implemented by turning
666        them into atomic groups such as ($>a+). Now they have their own opcodes,
667        which improves performance. This includes the automatically created ones
668        from 23 above.
670    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
671        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
672        the first matched character to be a colon. This applied both to named and
673        numbered groups.
675    29. The ucpinternal.h header file was missing its idempotency #ifdef.
677    30. I was sent a "project" file called libpcre.a.dev which I understand makes
678        building PCRE on Windows easier, so I have included it in the distribution.
680    31. There is now a check in pcretest against a ridiculously large number being
681        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
682        loop, the loop is abandoned.
684    32. Forward references to subpatterns in conditions such as (?(2)...) where
685        subpattern 2 is defined later cause pcre_compile() to search forwards in
686        the pattern for the relevant set of parentheses. This search went wrong
687        when there were unescaped parentheses in a character class, parentheses
688        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
690    33. "Subroutine" calls and backreferences were previously restricted to
691        referencing subpatterns earlier in the regex. This restriction has now
692        been removed.
694    34. Added a number of extra features that are going to be in Perl 5.10. On the
695        whole, these are just syntactic alternatives for features that PCRE had
696        previously implemented using the Python syntax or my own invention. The
697        other formats are all retained for compatibility.
699        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
700            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
701            also .NET compatible.
703        (b) A recursion or subroutine call to a named group can now be defined as
704            (?&name) as well as (?P>name).
706        (c) A backreference to a named group can now be defined as \k<name> or
707            \k'name' as well as (?P=name). The new forms, as well as being in Perl
708            5.10, are also .NET compatible.
710        (d) A conditional reference to a named group can now use the syntax
711            (?(<name>) or (?('name') as well as (?(name).
713        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
714            groups (named and numbered) that are never evaluated inline, but can be
715            called as "subroutines" from elsewhere. In effect, the DEFINE condition
716            is always false. There may be only one alternative in such a group.
718        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
719            as the simple (?(R). The condition is true only if the most recent
720            recursion is that of the given number or name. It does not search out
721            through the entire recursion stack.
723        (g) The escape \gN or \g{N} has been added, where N is a positive or
724            negative number, specifying an absolute or relative reference.
726    35. Tidied to get rid of some further signed/unsigned compiler warnings and
727        some "unreachable code" warnings.
729    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
730        things, this adds five new scripts.
732    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
733        There were also incompatibilities regarding the handling of \Q..\E inside
734        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
735        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
737    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
738        matches an empty string, and forcibly breaks the loop. There were bugs in
739        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
740        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
741        separate and independent bugs (that affected different cases) have been
742        fixed.
744    39. Refactored the code to abolish the use of different opcodes for small
745        capturing bracket numbers. This is a tidy that I avoided doing when I
746        removed the limit on the number of capturing brackets for 3.5 back in 2001.
747        The new approach is not only tidier, it makes it possible to reduce the
748        memory needed to fix the previous bug (38).
750    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
751        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
752        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
753        mode.
755    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
756        report.
758    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
759        copy construction and assignment in the C++ wrapper.
761    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
762        couple of bugs that could have given wrong results in the "--newline=crlf"
763        case.
765    44. Added a number of casts and did some reorganization of signed/unsigned int
766        variables following suggestions from Dair Grant. Also renamed the variable
767        "this" as "item" because it is a C++ keyword.
769    45. Arranged for dftables to add
771          #include "pcre_internal.h"
773        to pcre_chartables.c because without it, gcc 4.x may remove the array
774        definition from the final binary if PCRE is built into a static library and
775        dead code stripping is activated.
777    46. For an unanchored pattern, if a match attempt fails at the start of a
778        newline sequence, and the newline setting is CRLF or ANY, and the next two
779        characters are CRLF, advance by two characters instead of one.
782    Version 6.7 04-Jul-06
783    ---------------------
785     1. In order to handle tests when input lines are enormously long, pcretest has
786        been re-factored so that it automatically extends its buffers when
787        necessary. The code is crude, but this _is_ just a test program. The
788        default size has been increased from 32K to 50K.
790     2. The code in pcre_study() was using the value of the re argument before
791        testing it for NULL. (Of course, in any sensible call of the function, it
792        won't be NULL.)
794     3. The memmove() emulation function in pcre_internal.h, which is used on
795        systems that lack both memmove() and bcopy() - that is, hardly ever -
796        was missing a "static" storage class specifier.
798     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
799        containing an extended class (one that cannot be represented by a bitmap
800        because it contains high-valued characters or Unicode property items, e.g.
801        [\pZ]). Almost always one would set UTF-8 mode when processing such a
802        pattern, but PCRE should not loop if you do not (it no longer does).
803        [Detail: two cases were found: (a) a repeated subpattern containing an
804        extended class; (b) a recursive reference to a subpattern that followed a
805        previous extended class. It wasn't skipping over the extended class
806        correctly when UTF-8 mode was not set.]
808     5. A negated single-character class was not being recognized as fixed-length
809        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
810        compile error "lookbehind assertion is not fixed length".
812     6. The RunPerlTest auxiliary script was showing an unexpected difference
813        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
814        write a Perl script that can interpret lines of an input file either as
815        byte characters or as UTF-8, which is what "perltest" was being required to
816        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
817        can't do is switch easily at run time between having the "use utf8;" pragma
818        or not. In the end, I fudged it by using the RunPerlTest script to insert
819        "use utf8;" explicitly for the UTF-8 tests.
821     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
822        the end of the subject string, contrary to the documentation and to what
823        Perl does. This was true of both matching functions. Now it matches only at
824        the start of the subject and immediately after *internal* newlines.
826     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
827        a pointer to an int instead of a pointer to an unsigned long int. This
828        caused problems on 64-bit systems.
830     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
831        instance of the 'standard' template library not being so standard".
833    10. There was no check on the number of named subpatterns nor the maximum
834        length of a subpattern name. The product of these values is used to compute
835        the size of the memory block for a compiled pattern. By supplying a very
836        long subpattern name and a large number of named subpatterns, the size
837        computation could be caused to overflow. This is now prevented by limiting
838        the length of names to 32 characters, and the number of named subpatterns
839        to 10,000.
841    11. Subpatterns that are repeated with specific counts have to be replicated in
842        the compiled pattern. The size of memory for this was computed from the
843        length of the subpattern and the repeat count. The latter is limited to
844        65535, but there was no limit on the former, meaning that integer overflow
845        could in principle occur. The compiled length of a repeated subpattern is
846        now limited to 30,000 bytes in order to prevent this.
848    12. Added the optional facility to have named substrings with the same name.
850    13. Added the ability to use a named substring as a condition, using the
851        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
852        are numbers (not recommended). Forward references are permitted.
854    14. Added forward references in named backreferences (if you see what I mean).
856    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
857        pattern could run off the end of the subject. For example, the pattern
858        "(?s)(.{1,5})"8 did this with the subject "ab".
860    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
861        PCRE_CASELESS was set when matching characters that were quantified with ?
862        or *.
864    17. A character class other than a single negated character that had a minimum
865        but no maximum quantifier - for example [ab]{6,} - was not handled
866        correctly by pce_dfa_exec(). It would match only one character.
868    18. A valid (though odd) pattern that looked like a POSIX character
869        class but used an invalid character after [ (for example [[,abc,]]) caused
870        pcre_compile() to give the error "Failed: internal error: code overflow" or
871        in some cases to crash with a glibc free() error. This could even happen if
872        the pattern terminated after [[ but there just happened to be a sequence of
873        letters, a binary zero, and a closing ] in the memory that followed.
875    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
876        over the years. Originally (before any Unicode support), just the bottom 8
877        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
878        output from "man perlunicode" includes this:
880          The regular expression compiler produces polymorphic opcodes.  That
881          is, the pattern adapts to the data and automatically switches to
882          the Unicode character scheme when presented with Unicode data--or
883          instead uses a traditional byte scheme when presented with byte
884          data.
886        Sadly, a wide octal escape does not cause a switch, and in a string with
887        no other multibyte characters, these octal escapes are treated as before.
888        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
889        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
890        Unicode string.
892        I have not perpetrated such confusion in PCRE. Up till now, it took just
893        the bottom 8 bits, as in old Perl. I have now made octal escapes with
894        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
895        translate to the appropriate multibyte character.
897    29. Applied some refactoring to reduce the number of warnings from Microsoft
898        and Borland compilers. This has included removing the fudge introduced
899        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
900        a warning about an unused variable.
902    21. PCRE has not included VT (character 0x0b) in the set of whitespace
903        characters since release 4.0, because Perl (from release 5.004) does not.
904        [Or at least, is documented not to: some releases seem to be in conflict
905        with the documentation.] However, when a pattern was studied with
906        pcre_study() and all its branches started with \s, PCRE still included VT
907        as a possible starting character. Of course, this did no harm; it just
908        caused an unnecessary match attempt.
910    22. Removed a now-redundant internal flag bit that recorded the fact that case
911        dependency changed within the pattern. This was once needed for "required
912        byte" processing, but is no longer used. This recovers a now-scarce options
913        bit. Also moved the least significant internal flag bit to the most-
914        significant bit of the word, which was not previously used (hangover from
915        the days when it was an int rather than a uint) to free up another bit for
916        the future.
918    23. Added support for CRLF line endings as well as CR and LF. As well as the
919        default being selectable at build time, it can now be changed at runtime
920        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
921        specify that it is scanning data with non-default line endings.
923    24. Changed the definition of CXXLINK to make it agree with the definition of
924        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
926    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
927        recursions. This makes a big different to stack usage for some patterns.
929    26. If a subpattern containing a named recursion or subroutine reference such
930        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
931        the space required for the compiled pattern went wrong and gave too small a
932        value. Depending on the environment, this could lead to "Failed: internal
933        error: code overflow at offset 49" or "glibc detected double free or
934        corruption" errors.
936    27. Applied patches from Google (a) to support the new newline modes and (b) to
937        advance over multibyte UTF-8 characters in GlobalReplace.
939    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
940        difference for some implementation of PCRE in some Windows version.
942    29. Added some extra testing facilities to pcretest:
944        \q<number>   in a data line sets the "match limit" value
945        \Q<number>   in a data line sets the "match recursion limt" value
946        -S <number>  sets the stack size, where <number> is in megabytes
948        The -S option isn't available for Windows.
951    Version 6.6 06-Feb-06
952    ---------------------
954     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
955        in pcreposix.h. I have copied the definition from pcre.h.
957     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
958        because pcre.h is no longer a built file.
960     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
961        not normally included in the compiled code.
964    Version 6.5 01-Feb-06
965    ---------------------
967     1. When using the partial match feature with pcre_dfa_exec(), it was not
968        anchoring the second and subsequent partial matches at the new starting
969        point. This could lead to incorrect results. For example, with the pattern
970        /1234/, partially matching against "123" and then "a4" gave a match.
972     2. Changes to pcregrep:
974        (a) All non-match returns from pcre_exec() were being treated as failures
975            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
976            error message is output. Some extra information is given for the
977            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
978            probably the only errors that are likely to be caused by users (by
979            specifying a regex that has nested indefinite repeats, for instance).
980            If there are more than 20 of these errors, pcregrep is abandoned.
982        (b) A binary zero was treated as data while matching, but terminated the
983            output line if it was written out. This has been fixed: binary zeroes
984            are now no different to any other data bytes.
986        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
987            used to set a locale for matching. The --locale=xxxx long option has
988            been added (no short equivalent) to specify a locale explicitly on the
989            pcregrep command, overriding the environment variables.
991        (d) When -B was used with -n, some line numbers in the output were one less
992            than they should have been.
994        (e) Added the -o (--only-matching) option.
996        (f) If -A or -C was used with -c (count only), some lines of context were
997            accidentally printed for the final match.
999        (g) Added the -H (--with-filename) option.
1001        (h) The combination of options -rh failed to suppress file names for files
1002            that were found from directory arguments.
1004        (i) Added the -D (--devices) and -d (--directories) options.
1006        (j) Added the -F (--fixed-strings) option.
1008        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1010        (l) Added the --colo(u)r option.
1012        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1013            is not present by default.
1015     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1016        items such as (?R) or (?1), when the recursion could match a number of
1017        alternatives. If it matched one of the alternatives, but subsequently,
1018        outside the recursion, there was a failure, the code tried to back up into
1019        the recursion. However, because of the way PCRE is implemented, this is not
1020        possible, and the result was an incorrect result from the match.
1022        In order to prevent this happening, the specification of recursion has
1023        been changed so that all such subpatterns are automatically treated as
1024        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1026     4. I had overlooked the fact that, in some locales, there are characters for
1027        which isalpha() is true but neither isupper() nor islower() are true. In
1028        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1029        and ordfeminine) are like this. This affected the treatment of \w and \W
1030        when they appeared in character classes, but not when they appeared outside
1031        a character class. The bit map for "word" characters is now created
1032        separately from the results of isalnum() instead of just taking it from the
1033        upper, lower, and digit maps. (Plus the underscore character, of course.)
1035     5. The above bug also affected the handling of POSIX character classes such as
1036        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1037        permanent tables. Instead, the bit maps for such a class were previously
1038        created as the appropriate unions of the upper, lower, and digit bitmaps.
1039        Now they are created by subtraction from the [[:word:]] class, which has
1040        its own bitmap.
1042     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1043        It is created by subtracting the vertical space characters (\x09, \x0a,
1044        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1045        subtraction was done in the overall bitmap for a character class, meaning
1046        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1047        be recognized. This bug has been fixed.
1049     7. Patches from the folks at Google:
1051          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1052          real life, but is still worth protecting against".
1054          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1055          regular expressions".
1057          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1058          have it.
1060          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1061          "configure" and the latter not, in order to fix a problem somebody had
1062          with compiling the Arg class on HP-UX.
1064          (e) Improve the error-handling of the C++ wrapper a little bit.
1066          (f) New tests for checking recursion limiting.
1068     8. The pcre_memmove() function, which is used only if the environment does not
1069        have a standard memmove() function (and is therefore rarely compiled),
1070        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1071        returning a result (though PCRE never actually uses the result).
1073     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1074        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1075        returned instead of calling malloc() with an overflowing number that would
1076        most likely cause subsequent chaos.
1078    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1080    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1081        with this option is matched, the nmatch and pmatch options of regexec() are
1082        ignored.
1084    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1085        provided in case anyone wants to the the POSIX interface with UTF-8
1086        strings.
1088    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1089        C++ linking (needed for some HP-UX environments).
1091    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1092        (unused parameter) and in the pcre_printint() function (omitted "default"
1093        switch label when the default is to do nothing).
1095    15. Added some code to make it possible, when PCRE is compiled as a C++
1096        library, to replace subject pointers for pcre_exec() with a smart pointer
1097        class, thus making it possible to process discontinuous strings.
1099    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1100        much the same function. They were added by different people who were trying
1101        to make PCRE easy to compile on non-Unix systems. It has been suggested
1102        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1103        for compiling on Windows systems. I have therefore replaced it with
1104        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1105        defaults to "extern" for C or "extern C" for C++, which works fine on
1106        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1107        SCOPE with something explicit in config.h. In addition:
1109        (a) pcreposix.h still had just "extern" instead of either of these macros;
1110            I have replaced it with PCRE_DATA_SCOPE.
1112        (b) Functions such as _pcre_xclass(), which are internal to the library,
1113            but external in the C sense, all had PCRE_EXPORT in their definitions.
1114            This is apparently wrong for the Windows case, so I have removed it.
1115            (It makes no difference on Unix-like systems.)
1117    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1118        of recursive calls to match(). This is different to MATCH_LIMIT because
1119        that limits the total number of calls to match(), not all of which increase
1120        the depth of recursion. Limiting the recursion depth limits the amount of
1121        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1122        when PCRE is compiled, and changed at run time. A patch from Google adds
1123        this functionality to the C++ interface.
1125    18. Changes to the handling of Unicode character properties:
1127        (a) Updated the table to Unicode 4.1.0.
1129        (b) Recognize characters that are not in the table as "Cn" (undefined).
1131        (c) I revised the way the table is implemented to a much improved format
1132            which includes recognition of ranges. It now supports the ranges that
1133            are defined in UnicodeData.txt, and it also amalgamates other
1134            characters into ranges. This has reduced the number of entries in the
1135            table from around 16,000 to around 3,000, thus reducing its size
1136            considerably. I realized I did not need to use a tree structure after
1137            all - a binary chop search is just as efficient. Having reduced the
1138            number of entries, I extended their size from 6 bytes to 8 bytes to
1139            allow for more data.
1141        (d) Added support for Unicode script names via properties such as \p{Han}.
1143    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1144        matching that character.
1146    20. When matching a repeated Unicode property with a minimum greater than zero,
1147        (for example \pL{2,}), PCRE could look past the end of the subject if it
1148        reached it while seeking the minimum number of characters. This could
1149        happen only if some of the characters were more than one byte long, because
1150        there is a check for at least the minimum number of bytes.
1152    21. Refactored the implementation of \p and \P so as to be more general, to
1153        allow for more different types of property in future. This has changed the
1154        compiled form incompatibly. Anybody with saved compiled patterns that use
1155        \p or \P will have to recompile them.
1157    22. Added "Any" and "L&" to the supported property types.
1159    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1160        but give a compile time error if the value is greater than 0xff.
1162    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1163        accidentally not being installed or uninstalled.
1165    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1166        made were to insert the current release number. This seemed silly, because
1167        it made things harder for people building PCRE on systems that don't run
1168        "configure". I have turned pcre.h into a distributed file, no longer built
1169        by "configure", with the version identification directly included. There is
1170        no longer a pcre.h.in file.
1172        However, this change necessitated a change to the pcre-config script as
1173        well. It is built from pcre-config.in, and one of the substitutions was the
1174        release number. I have updated configure.ac so that ./configure now finds
1175        the release number by grepping pcre.h.
1177    26. Added the ability to run the tests under valgrind.
1180    Version 6.4 05-Sep-05
1181    ---------------------
1183     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1184        "--" to be printed when multiple files were scanned, even when none of the
1185        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1186        consider it to be a bug, and have restored the previous behaviour.
1188     2. A couple of code tidies to get rid of compiler warnings.
1190     3. The pcretest program used to cheat by referring to symbols in the library
1191        whose names begin with _pcre_. These are internal symbols that are not
1192        really supposed to be visible externally, and in some environments it is
1193        possible to suppress them. The cheating is now confined to including
1194        certain files from the library's source, which is a bit cleaner.
1196     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1197        file's purpose clearer.
1199     5. Reorganized pcre_ucp_findchar().
1202  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
1203  ---------------------  ---------------------

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