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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 284 by ph10, Fri Dec 7 20:01:16 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".
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
48    11. The program that makes PCRE's Unicode character property table had a bug
49        which caused it to generate incorrect table entries for sequences of
50        characters that have the same character type, but are in different scripts.
51        It amalgamated them into a single range, with the script of the first of
52        them. In other words, some characters were in the wrong script. There were
53        thirteen such cases, affecting characters in the following ranges:
55          U+002b0 - U+002c1
56          U+0060c - U+0060d
57          U+0061e - U+00612
58          U+0064b - U+0065e
59          U+0074d - U+0076d
60          U+01800 - U+01805
61          U+01d00 - U+01d77
62          U+01d9b - U+01dbf
63          U+0200b - U+0200f
64          U+030fc - U+030fe
65          U+03260 - U+0327f
66          U+0fb46 - U+0fbb1
67          U+10450 - U+1049d
69    12. The -o option (show only the matching part of a line) for pcregrep was not
70        compatible with GNU grep in that, if there was more than one match in a
71        line, it showed only the first of them. It now behaves in the same way as
72        GNU grep.
74    13. If the -o and -v options were combined for pcregrep, it printed a blank
75        line for every non-matching line. GNU grep prints nothing, and pcregrep now
76        does the same. The return code can be used to tell if there were any
77        non-matching lines.
79    14. The pattern (?=something)(?R) was not being diagnosed as a potentially
80        infinitely looping recursion. The bug was that positive lookaheads were not
81        being skipped when checking for a possible empty match (negative lookaheads
82        and both kinds of lookbehind were skipped).
84    15. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
85        inclusion of <windows.h> to before rather than after the definition of
86        INVALID_FILE_ATTRIBUTES (patch from David Byron).
89    Version 7.4 21-Sep-07
90    ---------------------
92    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
93        means that a class such as [\s] counted as "explicit reference to CR or
94        LF". That isn't really right - the whole point of the change was to try to
95        help when there was an actual mention of one of the two characters. So now
96        the change happens only if \r or \n (or a literal CR or LF) character is
97        encountered.
99    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
100        of both had grown to the point where there were only 3 bits left.
101        Fortunately, there was spare space in the data structure, and so I have
102        moved the internal flags into a new 16-bit field to free up more option
103        bits.
105    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
106        but did not set the internal JCHANGED flag - either of these is enough to
107        control the way the "get" function works - but the PCRE_INFO_JCHANGED
108        facility is supposed to tell if (?J) was ever used, so now (?J) at the
109        start sets both bits.
111    4.  Added options (at build time, compile time, exec time) to change \R from
112        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
114    5.  doc/pcresyntax.html was missing from the distribution.
116    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
117        compatibility, even though it is no longer used.
119    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
120        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
121        windows.h file is present (where different names are used). [This was
122        reversed later after testing - see 16 below.]
124    8.  Changed all #include <config.h> to #include "config.h". There were also
125        some further <pcre.h> cases that I changed to "pcre.h".
127    9.  When pcregrep was used with the --colour option, it missed the line ending
128        sequence off the lines that it output.
130    10. It was pointed out to me that arrays of string pointers cause lots of
131        relocations when a shared library is dynamically loaded. A technique of
132        using a single long string with a table of offsets can drastically reduce
133        these. I have refactored PCRE in four places to do this. The result is
134        dramatic:
136          Originally:                          290
137          After changing UCP table:            187
138          After changing error message table:   43
139          After changing table of "verbs"       36
140          After changing table of Posix names   22
142        Thanks to the folks working on Gregex for glib for this insight.
144    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
145        unicode-properties was also set.
147    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
149    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
150        checked only for CRLF.
152    14. Added casts to pcretest.c to avoid compiler warnings.
154    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
156    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
157        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
158        entirely. This removes changes made in 7 above.
160    17. The CMake files have been updated, and there is now more information about
161        building with CMake in the NON-UNIX-USE document.
164    Version 7.3 28-Aug-07
165    ---------------------
167     1. In the rejigging of the build system that eventually resulted in 7.1, the
168        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
169        brackets there is not right, since it causes compilers to look for an
170        installed pcre.h, not the version that is in the source that is being
171        compiled (which of course may be different). I have changed it back to:
173          #include "pcre.h"
175        I have a vague recollection that the change was concerned with compiling in
176        different directories, but in the new build system, that is taken care of
177        by the VPATH setting the Makefile.
179     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
180        when the subject happened to end in the byte 0x85 (e.g. if the last
181        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
182        characters but of course it shouldn't be taken as a newline when it is part
183        of another character. The bug was that, for an unlimited repeat of . in
184        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
185        characters when looking for a newline.
187     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
189     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
190        in debug output.
192     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
193        long printing in the pcrecpp unittest when running under MinGW.
195     6. ESC_K was left out of the EBCDIC table.
197     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
198        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
199        limit also applies to "virtual nesting" when a pattern is recursive, and in
200        this case 1000 isn't so big. I have been able to remove this limit at the
201        expense of backing off one optimization in certain circumstances. Normally,
202        when pcre_exec() would call its internal match() function recursively and
203        immediately return the result unconditionally, it uses a "tail recursion"
204        feature to save stack. However, when a subpattern that can match an empty
205        string has an unlimited repetition quantifier, it no longer makes this
206        optimization. That gives it a stack frame in which to save the data for
207        checking that an empty string has been matched. Previously this was taken
208        from the 1000-entry workspace that had been reserved. So now there is no
209        explicit limit, but more stack is used.
211     8. Applied Daniel's patches to solve problems with the import/export magic
212        syntax that is required for Windows, and which was going wrong for the
213        pcreposix and pcrecpp parts of the library. These were overlooked when this
214        problem was solved for the main library.
216     9. There were some crude static tests to avoid integer overflow when computing
217        the size of patterns that contain repeated groups with explicit upper
218        limits. As the maximum quantifier is 65535, the maximum group length was
219        set at 30,000 so that the product of these two numbers did not overflow a
220        32-bit integer. However, it turns out that people want to use groups that
221        are longer than 30,000 bytes (though not repeat them that many times).
222        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
223        made it possible to implement the integer overflow checks in a much more
224        dynamic way, which I have now done. The artificial limitation on group
225        length has been removed - we now have only the limit on the total length of
226        the compiled pattern, which depends on the LINK_SIZE setting.
228    10. Fixed a bug in the documentation for get/copy named substring when
229        duplicate names are permitted. If none of the named substrings are set, the
230        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
231        empty string.
233    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
234        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
235        because the ] is interpreted as the first data character and the
236        terminating ] is not found. PCRE has been made compatible with Perl in this
237        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
238        cause memory overwriting.
240    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
241        string has been matched (to stop an infinite loop). It was not recognizing
242        a conditional subpattern that could match an empty string if that
243        subpattern was within another subpattern. For example, it looped when
244        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
245        condition was not nested. This bug has been fixed.
247    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
248        past the start of the subject in the presence of bytes with the top bit
249        set, for example "\x8aBCD".
251    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
252        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
254    14. Optimized (?!) to (*FAIL).
256    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
257        This restricts code points to be within the range 0 to 0x10FFFF, excluding
258        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
259        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
260        does: it's just the validity check that is more restrictive.
262    16. Inserted checks for integer overflows during escape sequence (backslash)
263        processing, and also fixed erroneous offset values for syntax errors during
264        backslash processing.
266    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
267        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
269    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
270        caused an overrun.
272    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
273        something other than just ASCII characters) inside a group that had an
274        unlimited repeat caused a loop at compile time (while checking to see
275        whether the group could match an empty string).
277    20. Debugging a pattern containing \p or \P could cause a crash. For example,
278        [\P{Any}] did so. (Error in the code for printing property names.)
280    21. An orphan \E inside a character class could cause a crash.
282    22. A repeated capturing bracket such as (A)? could cause a wild memory
283        reference during compilation.
285    23. There are several functions in pcre_compile() that scan along a compiled
286        expression for various reasons (e.g. to see if it's fixed length for look
287        behind). There were bugs in these functions when a repeated \p or \P was
288        present in the pattern. These operators have additional parameters compared
289        with \d, etc, and these were not being taken into account when moving along
290        the compiled data. Specifically:
292        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
293            length.
295        (b) An item such as \pL+ within a repeated group could cause crashes or
296            loops.
298        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
299            "reference to non-existent subpattern" error.
301        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
303    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
304        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
306    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
308    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
309        character were causing crashes (broken optimization).
311    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
312        \p or \P) caused a compile-time loop.
314    28. More problems have arisen in unanchored patterns when CRLF is a valid line
315        break. For example, the unstudied pattern [\r\n]A does not match the string
316        "\r\nA" because change 7.0/46 below moves the current point on by two
317        characters after failing to match at the start. However, the pattern \nA
318        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
319        the same is true. There doesn't seem any very clean way out of this, but
320        what I have chosen to do makes the common cases work: PCRE now takes note
321        of whether there can be an explicit match for \r or \n anywhere in the
322        pattern, and if so, 7.0/46 no longer applies. As part of this change,
323        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
324        pattern has explicit CR or LF references.
326    29. Added (*CR) etc for changing newline setting at start of pattern.
329    Version 7.2 19-Jun-07
330    ---------------------
332     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
333        which is apparently normally available under Windows.
335     2. Re-jig the pcregrep tests with different newline settings in an attempt
336        to make them independent of the local environment's newline setting.
338     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
340     4. Some of the "internals" tests were previously cut out when the link size
341        was not 2, because the output contained actual offsets. The recent new
342        "Z" feature of pcretest means that these can be cut out, making the tests
343        usable with all link sizes.
345     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
346        stack recursion. This gives a massive performance boost under BSD, but just
347        a small improvement under Linux. However, it saves one field in the frame
348        in all cases.
350     6. Added more features from the forthcoming Perl 5.10:
352        (a) (?-n) (where n is a string of digits) is a relative subroutine or
353            recursion call. It refers to the nth most recently opened parentheses.
355        (b) (?+n) is also a relative subroutine call; it refers to the nth next
356            to be opened parentheses.
358        (c) Conditions that refer to capturing parentheses can be specified
359            relatively, for example, (?(-2)... or (?(+3)...
361        (d) \K resets the start of the current match so that everything before
362            is not part of it.
364        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
366        (f) \g{name} is another synonym - part of Perl 5.10's unification of
367            reference syntax.
369        (g) (?| introduces a group in which the numbering of parentheses in each
370            alternative starts with the same number.
372        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
374     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
377     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
378        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
379        for detecting groups that can match an empty string.
381     9. A pattern with a very large number of alternatives (more than several
382        hundred) was running out of internal workspace during the pre-compile
383        phase, where pcre_compile() figures out how much memory will be needed. A
384        bit of new cunning has reduced the workspace needed for groups with
385        alternatives. The 1000-alternative test pattern now uses 12 bytes of
386        workspace instead of running out of the 4096 that are available.
388    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
390    11. Applied patch from Google to remove an optimization that didn't quite work.
391        The report of the bug said:
393          pcrecpp::RE("a*").FullMatch("aaa") matches, while
394          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
395          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
397    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
398        it matched the wrong number of bytes.
401    Version 7.1 24-Apr-07
402    ---------------------
404     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
405        that is more "standard", making use of automake and other Autotools. There
406        is some re-arrangement of the files and adjustment of comments consequent
407        on this.
409     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
410        for recursive directory scanning broke on some systems because the files
411        are not scanned in any specific order and on different systems the order
412        was different. A call to "sort" has been inserted into RunGrepTest for the
413        approprate test as a short-term fix. In the longer term there may be an
414        alternative.
416     3. I had an email from Eric Raymond about problems translating some of PCRE's
417        man pages to HTML (despite the fact that I distribute HTML pages, some
418        people do their own conversions for various reasons). The problems
419        concerned the use of low-level troff macros .br and .in. I have therefore
420        removed all such uses from the man pages (some were redundant, some could
421        be replaced by .nf/.fi pairs). The 132html script that I use to generate
422        HTML has been updated to handle .nf/.fi and to complain if it encounters
423        .br or .in.
425     4. Updated comments in configure.ac that get placed in config.h.in and also
426        arranged for config.h to be included in the distribution, with the name
427        config.h.generic, for the benefit of those who have to compile without
428        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
430     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
431        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
432        makevp.bat for the current PCRE, using the additional files
433        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
435     6. A Windows user reported a minor discrepancy with test 2, which turned out
436        to be caused by a trailing space on an input line that had got lost in his
437        copy. The trailing space was an accident, so I've just removed it.
439     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
440        that is needed.
442     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
443        as "const" (a) because they are and (b) because it helps the PHP
444        maintainers who have recently made a script to detect big data structures
445        in the php code that should be moved to the .rodata section. I remembered
446        to update Builducptable as well, so it won't revert if ucptable.h is ever
447        re-created.
449     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
450        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
451        order to be able to cut out the UTF-8 tables in the latter when UTF-8
452        support is not required. This saves 1.5-2K of code, which is important in
453        some applications.
455        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
456        so as not to refer to the tables, even though these functions will never be
457        called when UTF-8 support is disabled. Otherwise there are problems with a
458        shared library.
460    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
462        (a) It was defining its arguments as char * instead of void *.
464        (b) It was assuming that all moves were upwards in memory; this was true
465            a long time ago when I wrote it, but is no longer the case.
467        The emulated memove() is provided for those environments that have neither
468        memmove() nor bcopy(). I didn't think anyone used it these days, but that
469        is clearly not the case, as these two bugs were recently reported.
471    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
472        and Detrail to create the HTML documentation, the .txt form of the man
473        pages, and it removes trailing spaces from listed files. It also creates
474        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
475        case, it wraps all the #defines with #ifndefs. This script should be run
476        before "make dist".
478    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
479        with Unicode property support.
481        (a) For a maximizing quantifier, if the two different cases of the
482            character were of different lengths in their UTF-8 codings (there are
483            some cases like this - I found 11), and the matching function had to
484            back up over a mixture of the two cases, it incorrectly assumed they
485            were both the same length.
487        (b) When PCRE was configured to use the heap rather than the stack for
488            recursion during matching, it was not correctly preserving the data for
489            the other case of a UTF-8 character when checking ahead for a match
490            while processing a minimizing repeat. If the check also involved
491            matching a wide character, but failed, corruption could cause an
492            erroneous result when trying to check for a repeat of the original
493            character.
495    13. Some tidying changes to the testing mechanism:
497        (a) The RunTest script now detects the internal link size and whether there
498            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
499            values substituted by "configure". (The RunGrepTest script already did
500            this for UTF-8.) The configure.ac script no longer substitutes the
501            relevant variables.
503        (b) The debugging options /B and /D in pcretest show the compiled bytecode
504            with length and offset values. This means that the output is different
505            for different internal link sizes. Test 2 is skipped for link sizes
506            other than 2 because of this, bypassing the problem. Unfortunately,
507            there was also a test in test 3 (the locale tests) that used /B and
508            failed for link sizes other than 2. Rather than cut the whole test out,
509            I have added a new /Z option to pcretest that replaces the length and
510            offset values with spaces. This is now used to make test 3 independent
511            of link size. (Test 2 will be tidied up later.)
513    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
514        segmentation fault instead of returning the appropriate error message.
516    15. In multiline mode when the newline sequence was set to "any", the pattern
517        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
518        This doesn't seem right; it now treats the CRLF combination as the line
519        ending, and so does not match in that case. It's only a pattern such as ^$
520        that would hit this one: something like ^ABC$ would have failed after \r
521        and then tried again after \r\n.
523    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
524        in an attempt to make files that differ only in their line terminators
525        compare equal. This works on Linux.
527    17. Under certain error circumstances pcregrep might try to free random memory
528        as it exited. This is now fixed, thanks to valgrind.
530    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
531        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
532        was because its rules for how to advance for /g after matching an empty
533        string at the end of a line did not allow for this case. They now check for
534        it specially.
536    20. pcretest is supposed to handle patterns and data of any length, by
537        extending its buffers when necessary. It was getting this wrong when the
538        buffer for a data line had to be extended.
540    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
541        CRLF as a newline sequence.
543    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
544        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
545        I have nevertheless tidied it up.
547    23. Added some casts to kill warnings from HP-UX ia64 compiler.
549    24. Added a man page for pcre-config.
552    Version 7.0 19-Dec-06
553    ---------------------
555     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
556        moving to gcc 4.1.1.
558     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
559        sys/time.h, which is documented as needed for this function. It doesn't
560        seem to matter on Linux, but it showed up on some releases of OS X.
562     3. It seems that there are systems where bytes whose values are greater than
563        127 match isprint() in the "C" locale. The "C" locale should be the
564        default when a C program starts up. In most systems, only ASCII printing
565        characters match isprint(). This difference caused the output from pcretest
566        to vary, making some of the tests fail. I have changed pcretest so that:
568        (a) When it is outputting text in the compiled version of a pattern, bytes
569            other than 32-126 are always shown as hex escapes.
571        (b) When it is outputting text that is a matched part of a subject string,
572            it does the same, unless a different locale has been set for the match
573            (using the /L modifier). In this case, it uses isprint() to decide.
575     4. Fixed a major bug that caused incorrect computation of the amount of memory
576        required for a compiled pattern when options that changed within the
577        pattern affected the logic of the preliminary scan that determines the
578        length. The relevant options are -x, and -i in UTF-8 mode. The result was
579        that the computed length was too small. The symptoms of this bug were
580        either the PCRE error "internal error: code overflow" from pcre_compile(),
581        or a glibc crash with a message such as "pcretest: free(): invalid next
582        size (fast)". Examples of patterns that provoked this bug (shown in
583        pcretest format) are:
585          /(?-x: )/x
586          /(?x)(?-x: \s*#\s*)/
587          /((?i)[\x{c0}])/8
588          /(?i:[\x{c0}])/8
590        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
591        is now done differently.
593     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
594        wrapper classes; (b) implement a new function in the C++ scanner that is
595        more efficient than the old way of doing things because it avoids levels of
596        recursion in the regex matching; (c) add a paragraph to the documentation
597        for the FullMatch() function.
599     6. The escape sequence \n was being treated as whatever was defined as
600        "newline". Not only was this contrary to the documentation, which states
601        that \n is character 10 (hex 0A), but it also went horribly wrong when
602        "newline" was defined as CRLF. This has been fixed.
604     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
605        was being set to -1 for the "end of line" case (supposedly a value that no
606        character can have). Though this value is never used (the check for end of
607        line is "zero bytes in current character"), it caused compiler complaints.
608        I've changed it to 0xffffffff.
610     8. In pcre_version.c, the version string was being built by a sequence of
611        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
612        string (as it is for production releases) called a macro with an empty
613        argument. The C standard says the result of this is undefined. The gcc
614        compiler treats it as an empty string (which was what was wanted) but it is
615        reported that Visual C gives an error. The source has been hacked around to
616        avoid this problem.
618     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
619        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
620        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
621        of them did).
623    10. Originally, pcretest opened its input and output without "b"; then I was
624        told that "b" was needed in some environments, so it was added for release
625        5.0 to both the input and output. (It makes no difference on Unix-like
626        systems.) Later I was told that it is wrong for the input on Windows. I've
627        now abstracted the modes into two macros, to make it easier to fiddle with
628        them, and removed "b" from the input mode under Windows.
630    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
632    12. Added -help and --help to pcretest as an official way of being reminded
633        of the options.
635    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
636        and pcrecpp.cc because they annoy compilers at high warning levels.
638    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
640    15. Fixed an occurrence of == in configure.ac that should have been = (shell
641        scripts are not C programs :-) and which was not noticed because it works
642        on Linux.
644    16. pcretest is supposed to handle any length of pattern and data line (as one
645        line or as a continued sequence of lines) by extending its input buffer if
646        necessary. This feature was broken for very long pattern lines, leading to
647        a string of junk being passed to pcre_compile() if the pattern was longer
648        than about 50K.
650    17. I have done a major re-factoring of the way pcre_compile() computes the
651        amount of memory needed for a compiled pattern. Previously, there was code
652        that made a preliminary scan of the pattern in order to do this. That was
653        OK when PCRE was new, but as the facilities have expanded, it has become
654        harder and harder to keep it in step with the real compile phase, and there
655        have been a number of bugs (see for example, 4 above). I have now found a
656        cunning way of running the real compile function in a "fake" mode that
657        enables it to compute how much memory it would need, while actually only
658        ever using a few hundred bytes of working memory and without too many
659        tests of the mode. This should make future maintenance and development
660        easier. A side effect of this work is that the limit of 200 on the nesting
661        depth of parentheses has been removed (though this was never a serious
662        limitation, I suspect). However, there is a downside: pcre_compile() now
663        runs more slowly than before (30% or more, depending on the pattern). I
664        hope this isn't a big issue. There is no effect on runtime performance.
666    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
667        newline (only possible for the last line of a file) and it was a
668        pattern that set a locale (followed by /Lsomething), pcretest crashed.
670    19. Added additional timing features to pcretest. (1) The -tm option now times
671        matching only, not compiling. (2) Both -t and -tm can be followed, as a
672        separate command line item, by a number that specifies the number of
673        repeats to use when timing. The default is 50000; this gives better
674        precision, but takes uncomfortably long for very large patterns.
676    20. Extended pcre_study() to be more clever in cases where a branch of a
677        subpattern has no definite first character. For example, (a*|b*)[cd] would
678        previously give no result from pcre_study(). Now it recognizes that the
679        first character must be a, b, c, or d.
681    21. There was an incorrect error "recursive call could loop indefinitely" if
682        a subpattern (or the entire pattern) that was being tested for matching an
683        empty string contained only one non-empty item after a nested subpattern.
684        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
685        incorrectly, because the \d was being skipped in the check.
687    22. The pcretest program now has a new pattern option /B and a command line
688        option -b, which is equivalent to adding /B to every pattern. This causes
689        it to show the compiled bytecode, without the additional information that
690        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
691        is the same as /B/I).
693    23. A new optimization is now able automatically to treat some sequences such
694        as a*b as a*+b. More specifically, if something simple (such as a character
695        or a simple class like \d) has an unlimited quantifier, and is followed by
696        something that cannot possibly match the quantified thing, the quantifier
697        is automatically "possessified".
699    24. A recursive reference to a subpattern whose number was greater than 39
700        went wrong under certain circumstances in UTF-8 mode. This bug could also
701        have affected the operation of pcre_study().
703    25. Realized that a little bit of performance could be had by replacing
704        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
706    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
708    27. Possessive quantifiers such as a++ were previously implemented by turning
709        them into atomic groups such as ($>a+). Now they have their own opcodes,
710        which improves performance. This includes the automatically created ones
711        from 23 above.
713    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
714        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
715        the first matched character to be a colon. This applied both to named and
716        numbered groups.
718    29. The ucpinternal.h header file was missing its idempotency #ifdef.
720    30. I was sent a "project" file called libpcre.a.dev which I understand makes
721        building PCRE on Windows easier, so I have included it in the distribution.
723    31. There is now a check in pcretest against a ridiculously large number being
724        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
725        loop, the loop is abandoned.
727    32. Forward references to subpatterns in conditions such as (?(2)...) where
728        subpattern 2 is defined later cause pcre_compile() to search forwards in
729        the pattern for the relevant set of parentheses. This search went wrong
730        when there were unescaped parentheses in a character class, parentheses
731        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
733    33. "Subroutine" calls and backreferences were previously restricted to
734        referencing subpatterns earlier in the regex. This restriction has now
735        been removed.
737    34. Added a number of extra features that are going to be in Perl 5.10. On the
738        whole, these are just syntactic alternatives for features that PCRE had
739        previously implemented using the Python syntax or my own invention. The
740        other formats are all retained for compatibility.
742        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
743            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
744            also .NET compatible.
746        (b) A recursion or subroutine call to a named group can now be defined as
747            (?&name) as well as (?P>name).
749        (c) A backreference to a named group can now be defined as \k<name> or
750            \k'name' as well as (?P=name). The new forms, as well as being in Perl
751            5.10, are also .NET compatible.
753        (d) A conditional reference to a named group can now use the syntax
754            (?(<name>) or (?('name') as well as (?(name).
756        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
757            groups (named and numbered) that are never evaluated inline, but can be
758            called as "subroutines" from elsewhere. In effect, the DEFINE condition
759            is always false. There may be only one alternative in such a group.
761        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
762            as the simple (?(R). The condition is true only if the most recent
763            recursion is that of the given number or name. It does not search out
764            through the entire recursion stack.
766        (g) The escape \gN or \g{N} has been added, where N is a positive or
767            negative number, specifying an absolute or relative reference.
769    35. Tidied to get rid of some further signed/unsigned compiler warnings and
770        some "unreachable code" warnings.
772    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
773        things, this adds five new scripts.
775    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
776        There were also incompatibilities regarding the handling of \Q..\E inside
777        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
778        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
780    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
781        matches an empty string, and forcibly breaks the loop. There were bugs in
782        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
783        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
784        separate and independent bugs (that affected different cases) have been
785        fixed.
787    39. Refactored the code to abolish the use of different opcodes for small
788        capturing bracket numbers. This is a tidy that I avoided doing when I
789        removed the limit on the number of capturing brackets for 3.5 back in 2001.
790        The new approach is not only tidier, it makes it possible to reduce the
791        memory needed to fix the previous bug (38).
793    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
794        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
795        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
796        mode.
798    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
799        report.
801    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
802        copy construction and assignment in the C++ wrapper.
804    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
805        couple of bugs that could have given wrong results in the "--newline=crlf"
806        case.
808    44. Added a number of casts and did some reorganization of signed/unsigned int
809        variables following suggestions from Dair Grant. Also renamed the variable
810        "this" as "item" because it is a C++ keyword.
812    45. Arranged for dftables to add
814          #include "pcre_internal.h"
816        to pcre_chartables.c because without it, gcc 4.x may remove the array
817        definition from the final binary if PCRE is built into a static library and
818        dead code stripping is activated.
820    46. For an unanchored pattern, if a match attempt fails at the start of a
821        newline sequence, and the newline setting is CRLF or ANY, and the next two
822        characters are CRLF, advance by two characters instead of one.
825  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
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