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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 268 by ph10, Thu Nov 15 10:28:09 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.5 12-Nov-07
5    ---------------------
6    
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."
9    
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.
13    
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
16    
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.
20    
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).
25    
26    
27    Version 7.4 21-Sep-07
28    ---------------------
29    
30    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
31        means that a class such as [\s] counted as "explicit reference to CR or
32        LF". That isn't really right - the whole point of the change was to try to
33        help when there was an actual mention of one of the two characters. So now
34        the change happens only if \r or \n (or a literal CR or LF) character is
35        encountered.
36    
37    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
38        of both had grown to the point where there were only 3 bits left.
39        Fortunately, there was spare space in the data structure, and so I have
40        moved the internal flags into a new 16-bit field to free up more option
41        bits.
42    
43    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
44        but did not set the internal JCHANGED flag - either of these is enough to
45        control the way the "get" function works - but the PCRE_INFO_JCHANGED
46        facility is supposed to tell if (?J) was ever used, so now (?J) at the
47        start sets both bits.
48    
49    4.  Added options (at build time, compile time, exec time) to change \R from
50        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
51    
52    5.  doc/pcresyntax.html was missing from the distribution.
53    
54    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
55        compatibility, even though it is no longer used.
56    
57    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
58        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
59        windows.h file is present (where different names are used). [This was
60        reversed later after testing - see 16 below.]
61    
62    8.  Changed all #include <config.h> to #include "config.h". There were also
63        some further <pcre.h> cases that I changed to "pcre.h".
64    
65    9.  When pcregrep was used with the --colour option, it missed the line ending
66        sequence off the lines that it output.
67    
68    10. It was pointed out to me that arrays of string pointers cause lots of
69        relocations when a shared library is dynamically loaded. A technique of
70        using a single long string with a table of offsets can drastically reduce
71        these. I have refactored PCRE in four places to do this. The result is
72        dramatic:
73    
74          Originally:                          290
75          After changing UCP table:            187
76          After changing error message table:   43
77          After changing table of "verbs"       36
78          After changing table of Posix names   22
79    
80        Thanks to the folks working on Gregex for glib for this insight.
81    
82    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
83        unicode-properties was also set.
84    
85    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
86    
87    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
88        checked only for CRLF.
89    
90    14. Added casts to pcretest.c to avoid compiler warnings.
91    
92    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
93    
94    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
95        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
96        entirely. This removes changes made in 7 above.
97    
98    17. The CMake files have been updated, and there is now more information about
99        building with CMake in the NON-UNIX-USE document.
100    
101    
102    Version 7.3 28-Aug-07
103    ---------------------
104    
105     1. In the rejigging of the build system that eventually resulted in 7.1, the
106        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
107        brackets there is not right, since it causes compilers to look for an
108        installed pcre.h, not the version that is in the source that is being
109        compiled (which of course may be different). I have changed it back to:
110    
111          #include "pcre.h"
112    
113        I have a vague recollection that the change was concerned with compiling in
114        different directories, but in the new build system, that is taken care of
115        by the VPATH setting the Makefile.
116    
117     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
118        when the subject happened to end in the byte 0x85 (e.g. if the last
119        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
120        characters but of course it shouldn't be taken as a newline when it is part
121        of another character. The bug was that, for an unlimited repeat of . in
122        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
123        characters when looking for a newline.
124    
125     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
126    
127     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
128        in debug output.
129    
130     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
131        long printing in the pcrecpp unittest when running under MinGW.
132    
133     6. ESC_K was left out of the EBCDIC table.
134    
135     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
136        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
137        limit also applies to "virtual nesting" when a pattern is recursive, and in
138        this case 1000 isn't so big. I have been able to remove this limit at the
139        expense of backing off one optimization in certain circumstances. Normally,
140        when pcre_exec() would call its internal match() function recursively and
141        immediately return the result unconditionally, it uses a "tail recursion"
142        feature to save stack. However, when a subpattern that can match an empty
143        string has an unlimited repetition quantifier, it no longer makes this
144        optimization. That gives it a stack frame in which to save the data for
145        checking that an empty string has been matched. Previously this was taken
146        from the 1000-entry workspace that had been reserved. So now there is no
147        explicit limit, but more stack is used.
148    
149     8. Applied Daniel's patches to solve problems with the import/export magic
150        syntax that is required for Windows, and which was going wrong for the
151        pcreposix and pcrecpp parts of the library. These were overlooked when this
152        problem was solved for the main library.
153    
154     9. There were some crude static tests to avoid integer overflow when computing
155        the size of patterns that contain repeated groups with explicit upper
156        limits. As the maximum quantifier is 65535, the maximum group length was
157        set at 30,000 so that the product of these two numbers did not overflow a
158        32-bit integer. However, it turns out that people want to use groups that
159        are longer than 30,000 bytes (though not repeat them that many times).
160        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
161        made it possible to implement the integer overflow checks in a much more
162        dynamic way, which I have now done. The artificial limitation on group
163        length has been removed - we now have only the limit on the total length of
164        the compiled pattern, which depends on the LINK_SIZE setting.
165    
166    10. Fixed a bug in the documentation for get/copy named substring when
167        duplicate names are permitted. If none of the named substrings are set, the
168        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
169        empty string.
170    
171    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
172        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
173        because the ] is interpreted as the first data character and the
174        terminating ] is not found. PCRE has been made compatible with Perl in this
175        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
176        cause memory overwriting.
177    
178    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
179        string has been matched (to stop an infinite loop). It was not recognizing
180        a conditional subpattern that could match an empty string if that
181        subpattern was within another subpattern. For example, it looped when
182        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
183        condition was not nested. This bug has been fixed.
184    
185    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
186        past the start of the subject in the presence of bytes with the top bit
187        set, for example "\x8aBCD".
188    
189    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
190        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
191    
192    14. Optimized (?!) to (*FAIL).
193    
194    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
195        This restricts code points to be within the range 0 to 0x10FFFF, excluding
196        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
197        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
198        does: it's just the validity check that is more restrictive.
199    
200    16. Inserted checks for integer overflows during escape sequence (backslash)
201        processing, and also fixed erroneous offset values for syntax errors during
202        backslash processing.
203    
204    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
205        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
206    
207    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
208        caused an overrun.
209    
210    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
211        something other than just ASCII characters) inside a group that had an
212        unlimited repeat caused a loop at compile time (while checking to see
213        whether the group could match an empty string).
214    
215    20. Debugging a pattern containing \p or \P could cause a crash. For example,
216        [\P{Any}] did so. (Error in the code for printing property names.)
217    
218    21. An orphan \E inside a character class could cause a crash.
219    
220    22. A repeated capturing bracket such as (A)? could cause a wild memory
221        reference during compilation.
222    
223    23. There are several functions in pcre_compile() that scan along a compiled
224        expression for various reasons (e.g. to see if it's fixed length for look
225        behind). There were bugs in these functions when a repeated \p or \P was
226        present in the pattern. These operators have additional parameters compared
227        with \d, etc, and these were not being taken into account when moving along
228        the compiled data. Specifically:
229    
230        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
231            length.
232    
233        (b) An item such as \pL+ within a repeated group could cause crashes or
234            loops.
235    
236        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
237            "reference to non-existent subpattern" error.
238    
239        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
240    
241    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
242        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
243    
244    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
245    
246    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
247        character were causing crashes (broken optimization).
248    
249    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
250        \p or \P) caused a compile-time loop.
251    
252    28. More problems have arisen in unanchored patterns when CRLF is a valid line
253        break. For example, the unstudied pattern [\r\n]A does not match the string
254        "\r\nA" because change 7.0/46 below moves the current point on by two
255        characters after failing to match at the start. However, the pattern \nA
256        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
257        the same is true. There doesn't seem any very clean way out of this, but
258        what I have chosen to do makes the common cases work: PCRE now takes note
259        of whether there can be an explicit match for \r or \n anywhere in the
260        pattern, and if so, 7.0/46 no longer applies. As part of this change,
261        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
262        pattern has explicit CR or LF references.
263    
264    29. Added (*CR) etc for changing newline setting at start of pattern.
265    
266    
267    Version 7.2 19-Jun-07
268    ---------------------
269    
270     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
271        which is apparently normally available under Windows.
272    
273     2. Re-jig the pcregrep tests with different newline settings in an attempt
274        to make them independent of the local environment's newline setting.
275    
276     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
277    
278     4. Some of the "internals" tests were previously cut out when the link size
279        was not 2, because the output contained actual offsets. The recent new
280        "Z" feature of pcretest means that these can be cut out, making the tests
281        usable with all link sizes.
282    
283     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
284        stack recursion. This gives a massive performance boost under BSD, but just
285        a small improvement under Linux. However, it saves one field in the frame
286        in all cases.
287    
288     6. Added more features from the forthcoming Perl 5.10:
289    
290        (a) (?-n) (where n is a string of digits) is a relative subroutine or
291            recursion call. It refers to the nth most recently opened parentheses.
292    
293        (b) (?+n) is also a relative subroutine call; it refers to the nth next
294            to be opened parentheses.
295    
296        (c) Conditions that refer to capturing parentheses can be specified
297            relatively, for example, (?(-2)... or (?(+3)...
298    
299        (d) \K resets the start of the current match so that everything before
300            is not part of it.
301    
302        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
303    
304        (f) \g{name} is another synonym - part of Perl 5.10's unification of
305            reference syntax.
306    
307        (g) (?| introduces a group in which the numbering of parentheses in each
308            alternative starts with the same number.
309    
310        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
311    
312     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
313        PCRE_INFO_JCHANGED.
314    
315     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
316        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
317        for detecting groups that can match an empty string.
318    
319     9. A pattern with a very large number of alternatives (more than several
320        hundred) was running out of internal workspace during the pre-compile
321        phase, where pcre_compile() figures out how much memory will be needed. A
322        bit of new cunning has reduced the workspace needed for groups with
323        alternatives. The 1000-alternative test pattern now uses 12 bytes of
324        workspace instead of running out of the 4096 that are available.
325    
326    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
327    
328    11. Applied patch from Google to remove an optimization that didn't quite work.
329        The report of the bug said:
330    
331          pcrecpp::RE("a*").FullMatch("aaa") matches, while
332          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
333          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
334    
335    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
336        it matched the wrong number of bytes.
337    
338    
339    Version 7.1 24-Apr-07
340    ---------------------
341    
342     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
343        that is more "standard", making use of automake and other Autotools. There
344        is some re-arrangement of the files and adjustment of comments consequent
345        on this.
346    
347     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
348        for recursive directory scanning broke on some systems because the files
349        are not scanned in any specific order and on different systems the order
350        was different. A call to "sort" has been inserted into RunGrepTest for the
351        approprate test as a short-term fix. In the longer term there may be an
352        alternative.
353    
354     3. I had an email from Eric Raymond about problems translating some of PCRE's
355        man pages to HTML (despite the fact that I distribute HTML pages, some
356        people do their own conversions for various reasons). The problems
357        concerned the use of low-level troff macros .br and .in. I have therefore
358        removed all such uses from the man pages (some were redundant, some could
359        be replaced by .nf/.fi pairs). The 132html script that I use to generate
360        HTML has been updated to handle .nf/.fi and to complain if it encounters
361        .br or .in.
362    
363     4. Updated comments in configure.ac that get placed in config.h.in and also
364        arranged for config.h to be included in the distribution, with the name
365        config.h.generic, for the benefit of those who have to compile without
366        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
367    
368     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
369        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
370        makevp.bat for the current PCRE, using the additional files
371        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
372    
373     6. A Windows user reported a minor discrepancy with test 2, which turned out
374        to be caused by a trailing space on an input line that had got lost in his
375        copy. The trailing space was an accident, so I've just removed it.
376    
377     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
378        that is needed.
379    
380     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
381        as "const" (a) because they are and (b) because it helps the PHP
382        maintainers who have recently made a script to detect big data structures
383        in the php code that should be moved to the .rodata section. I remembered
384        to update Builducptable as well, so it won't revert if ucptable.h is ever
385        re-created.
386    
387     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
388        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
389        order to be able to cut out the UTF-8 tables in the latter when UTF-8
390        support is not required. This saves 1.5-2K of code, which is important in
391        some applications.
392    
393        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
394        so as not to refer to the tables, even though these functions will never be
395        called when UTF-8 support is disabled. Otherwise there are problems with a
396        shared library.
397    
398    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
399    
400        (a) It was defining its arguments as char * instead of void *.
401    
402        (b) It was assuming that all moves were upwards in memory; this was true
403            a long time ago when I wrote it, but is no longer the case.
404    
405        The emulated memove() is provided for those environments that have neither
406        memmove() nor bcopy(). I didn't think anyone used it these days, but that
407        is clearly not the case, as these two bugs were recently reported.
408    
409    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
410        and Detrail to create the HTML documentation, the .txt form of the man
411        pages, and it removes trailing spaces from listed files. It also creates
412        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
413        case, it wraps all the #defines with #ifndefs. This script should be run
414        before "make dist".
415    
416    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
417        with Unicode property support.
418    
419        (a) For a maximizing quantifier, if the two different cases of the
420            character were of different lengths in their UTF-8 codings (there are
421            some cases like this - I found 11), and the matching function had to
422            back up over a mixture of the two cases, it incorrectly assumed they
423            were both the same length.
424    
425        (b) When PCRE was configured to use the heap rather than the stack for
426            recursion during matching, it was not correctly preserving the data for
427            the other case of a UTF-8 character when checking ahead for a match
428            while processing a minimizing repeat. If the check also involved
429            matching a wide character, but failed, corruption could cause an
430            erroneous result when trying to check for a repeat of the original
431            character.
432    
433    13. Some tidying changes to the testing mechanism:
434    
435        (a) The RunTest script now detects the internal link size and whether there
436            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
437            values substituted by "configure". (The RunGrepTest script already did
438            this for UTF-8.) The configure.ac script no longer substitutes the
439            relevant variables.
440    
441        (b) The debugging options /B and /D in pcretest show the compiled bytecode
442            with length and offset values. This means that the output is different
443            for different internal link sizes. Test 2 is skipped for link sizes
444            other than 2 because of this, bypassing the problem. Unfortunately,
445            there was also a test in test 3 (the locale tests) that used /B and
446            failed for link sizes other than 2. Rather than cut the whole test out,
447            I have added a new /Z option to pcretest that replaces the length and
448            offset values with spaces. This is now used to make test 3 independent
449            of link size. (Test 2 will be tidied up later.)
450    
451    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
452        segmentation fault instead of returning the appropriate error message.
453    
454    15. In multiline mode when the newline sequence was set to "any", the pattern
455        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
456        This doesn't seem right; it now treats the CRLF combination as the line
457        ending, and so does not match in that case. It's only a pattern such as ^$
458        that would hit this one: something like ^ABC$ would have failed after \r
459        and then tried again after \r\n.
460    
461    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
462        in an attempt to make files that differ only in their line terminators
463        compare equal. This works on Linux.
464    
465    17. Under certain error circumstances pcregrep might try to free random memory
466        as it exited. This is now fixed, thanks to valgrind.
467    
468    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
469        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
470        was because its rules for how to advance for /g after matching an empty
471        string at the end of a line did not allow for this case. They now check for
472        it specially.
473    
474    20. pcretest is supposed to handle patterns and data of any length, by
475        extending its buffers when necessary. It was getting this wrong when the
476        buffer for a data line had to be extended.
477    
478    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
479        CRLF as a newline sequence.
480    
481    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
482        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
483        I have nevertheless tidied it up.
484    
485    23. Added some casts to kill warnings from HP-UX ia64 compiler.
486    
487    24. Added a man page for pcre-config.
488    
489    
490    Version 7.0 19-Dec-06
491    ---------------------
492    
493     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
494        moving to gcc 4.1.1.
495    
496     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
497        sys/time.h, which is documented as needed for this function. It doesn't
498        seem to matter on Linux, but it showed up on some releases of OS X.
499    
500     3. It seems that there are systems where bytes whose values are greater than
501        127 match isprint() in the "C" locale. The "C" locale should be the
502        default when a C program starts up. In most systems, only ASCII printing
503        characters match isprint(). This difference caused the output from pcretest
504        to vary, making some of the tests fail. I have changed pcretest so that:
505    
506        (a) When it is outputting text in the compiled version of a pattern, bytes
507            other than 32-126 are always shown as hex escapes.
508    
509        (b) When it is outputting text that is a matched part of a subject string,
510            it does the same, unless a different locale has been set for the match
511            (using the /L modifier). In this case, it uses isprint() to decide.
512    
513     4. Fixed a major bug that caused incorrect computation of the amount of memory
514        required for a compiled pattern when options that changed within the
515        pattern affected the logic of the preliminary scan that determines the
516        length. The relevant options are -x, and -i in UTF-8 mode. The result was
517        that the computed length was too small. The symptoms of this bug were
518        either the PCRE error "internal error: code overflow" from pcre_compile(),
519        or a glibc crash with a message such as "pcretest: free(): invalid next
520        size (fast)". Examples of patterns that provoked this bug (shown in
521        pcretest format) are:
522    
523          /(?-x: )/x
524          /(?x)(?-x: \s*#\s*)/
525          /((?i)[\x{c0}])/8
526          /(?i:[\x{c0}])/8
527    
528        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
529        is now done differently.
530    
531     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
532        wrapper classes; (b) implement a new function in the C++ scanner that is
533        more efficient than the old way of doing things because it avoids levels of
534        recursion in the regex matching; (c) add a paragraph to the documentation
535        for the FullMatch() function.
536    
537     6. The escape sequence \n was being treated as whatever was defined as
538        "newline". Not only was this contrary to the documentation, which states
539        that \n is character 10 (hex 0A), but it also went horribly wrong when
540        "newline" was defined as CRLF. This has been fixed.
541    
542     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
543        was being set to -1 for the "end of line" case (supposedly a value that no
544        character can have). Though this value is never used (the check for end of
545        line is "zero bytes in current character"), it caused compiler complaints.
546        I've changed it to 0xffffffff.
547    
548     8. In pcre_version.c, the version string was being built by a sequence of
549        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
550        string (as it is for production releases) called a macro with an empty
551        argument. The C standard says the result of this is undefined. The gcc
552        compiler treats it as an empty string (which was what was wanted) but it is
553        reported that Visual C gives an error. The source has been hacked around to
554        avoid this problem.
555    
556     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
557        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
558        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
559        of them did).
560    
561    10. Originally, pcretest opened its input and output without "b"; then I was
562        told that "b" was needed in some environments, so it was added for release
563        5.0 to both the input and output. (It makes no difference on Unix-like
564        systems.) Later I was told that it is wrong for the input on Windows. I've
565        now abstracted the modes into two macros, to make it easier to fiddle with
566        them, and removed "b" from the input mode under Windows.
567    
568    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
569    
570    12. Added -help and --help to pcretest as an official way of being reminded
571        of the options.
572    
573    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
574        and pcrecpp.cc because they annoy compilers at high warning levels.
575    
576    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
577    
578    15. Fixed an occurrence of == in configure.ac that should have been = (shell
579        scripts are not C programs :-) and which was not noticed because it works
580        on Linux.
581    
582    16. pcretest is supposed to handle any length of pattern and data line (as one
583        line or as a continued sequence of lines) by extending its input buffer if
584        necessary. This feature was broken for very long pattern lines, leading to
585        a string of junk being passed to pcre_compile() if the pattern was longer
586        than about 50K.
587    
588    17. I have done a major re-factoring of the way pcre_compile() computes the
589        amount of memory needed for a compiled pattern. Previously, there was code
590        that made a preliminary scan of the pattern in order to do this. That was
591        OK when PCRE was new, but as the facilities have expanded, it has become
592        harder and harder to keep it in step with the real compile phase, and there
593        have been a number of bugs (see for example, 4 above). I have now found a
594        cunning way of running the real compile function in a "fake" mode that
595        enables it to compute how much memory it would need, while actually only
596        ever using a few hundred bytes of working memory and without too many
597        tests of the mode. This should make future maintenance and development
598        easier. A side effect of this work is that the limit of 200 on the nesting
599        depth of parentheses has been removed (though this was never a serious
600        limitation, I suspect). However, there is a downside: pcre_compile() now
601        runs more slowly than before (30% or more, depending on the pattern). I
602        hope this isn't a big issue. There is no effect on runtime performance.
603    
604    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
605        newline (only possible for the last line of a file) and it was a
606        pattern that set a locale (followed by /Lsomething), pcretest crashed.
607    
608    19. Added additional timing features to pcretest. (1) The -tm option now times
609        matching only, not compiling. (2) Both -t and -tm can be followed, as a
610        separate command line item, by a number that specifies the number of
611        repeats to use when timing. The default is 50000; this gives better
612        precision, but takes uncomfortably long for very large patterns.
613    
614    20. Extended pcre_study() to be more clever in cases where a branch of a
615        subpattern has no definite first character. For example, (a*|b*)[cd] would
616        previously give no result from pcre_study(). Now it recognizes that the
617        first character must be a, b, c, or d.
618    
619    21. There was an incorrect error "recursive call could loop indefinitely" if
620        a subpattern (or the entire pattern) that was being tested for matching an
621        empty string contained only one non-empty item after a nested subpattern.
622        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
623        incorrectly, because the \d was being skipped in the check.
624    
625    22. The pcretest program now has a new pattern option /B and a command line
626        option -b, which is equivalent to adding /B to every pattern. This causes
627        it to show the compiled bytecode, without the additional information that
628        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
629        is the same as /B/I).
630    
631    23. A new optimization is now able automatically to treat some sequences such
632        as a*b as a*+b. More specifically, if something simple (such as a character
633        or a simple class like \d) has an unlimited quantifier, and is followed by
634        something that cannot possibly match the quantified thing, the quantifier
635        is automatically "possessified".
636    
637    24. A recursive reference to a subpattern whose number was greater than 39
638        went wrong under certain circumstances in UTF-8 mode. This bug could also
639        have affected the operation of pcre_study().
640    
641    25. Realized that a little bit of performance could be had by replacing
642        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
643    
644    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
645    
646    27. Possessive quantifiers such as a++ were previously implemented by turning
647        them into atomic groups such as ($>a+). Now they have their own opcodes,
648        which improves performance. This includes the automatically created ones
649        from 23 above.
650    
651    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
652        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
653        the first matched character to be a colon. This applied both to named and
654        numbered groups.
655    
656    29. The ucpinternal.h header file was missing its idempotency #ifdef.
657    
658    30. I was sent a "project" file called libpcre.a.dev which I understand makes
659        building PCRE on Windows easier, so I have included it in the distribution.
660    
661    31. There is now a check in pcretest against a ridiculously large number being
662        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
663        loop, the loop is abandoned.
664    
665    32. Forward references to subpatterns in conditions such as (?(2)...) where
666        subpattern 2 is defined later cause pcre_compile() to search forwards in
667        the pattern for the relevant set of parentheses. This search went wrong
668        when there were unescaped parentheses in a character class, parentheses
669        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
670    
671    33. "Subroutine" calls and backreferences were previously restricted to
672        referencing subpatterns earlier in the regex. This restriction has now
673        been removed.
674    
675    34. Added a number of extra features that are going to be in Perl 5.10. On the
676        whole, these are just syntactic alternatives for features that PCRE had
677        previously implemented using the Python syntax or my own invention. The
678        other formats are all retained for compatibility.
679    
680        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
681            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
682            also .NET compatible.
683    
684        (b) A recursion or subroutine call to a named group can now be defined as
685            (?&name) as well as (?P>name).
686    
687        (c) A backreference to a named group can now be defined as \k<name> or
688            \k'name' as well as (?P=name). The new forms, as well as being in Perl
689            5.10, are also .NET compatible.
690    
691        (d) A conditional reference to a named group can now use the syntax
692            (?(<name>) or (?('name') as well as (?(name).
693    
694        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
695            groups (named and numbered) that are never evaluated inline, but can be
696            called as "subroutines" from elsewhere. In effect, the DEFINE condition
697            is always false. There may be only one alternative in such a group.
698    
699        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
700            as the simple (?(R). The condition is true only if the most recent
701            recursion is that of the given number or name. It does not search out
702            through the entire recursion stack.
703    
704        (g) The escape \gN or \g{N} has been added, where N is a positive or
705            negative number, specifying an absolute or relative reference.
706    
707    35. Tidied to get rid of some further signed/unsigned compiler warnings and
708        some "unreachable code" warnings.
709    
710    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
711        things, this adds five new scripts.
712    
713    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
714        There were also incompatibilities regarding the handling of \Q..\E inside
715        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
716        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
717    
718    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
719        matches an empty string, and forcibly breaks the loop. There were bugs in
720        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
721        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
722        separate and independent bugs (that affected different cases) have been
723        fixed.
724    
725    39. Refactored the code to abolish the use of different opcodes for small
726        capturing bracket numbers. This is a tidy that I avoided doing when I
727        removed the limit on the number of capturing brackets for 3.5 back in 2001.
728        The new approach is not only tidier, it makes it possible to reduce the
729        memory needed to fix the previous bug (38).
730    
731    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
732        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
733        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
734        mode.
735    
736    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
737        report.
738    
739    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
740        copy construction and assignment in the C++ wrapper.
741    
742    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
743        couple of bugs that could have given wrong results in the "--newline=crlf"
744        case.
745    
746    44. Added a number of casts and did some reorganization of signed/unsigned int
747        variables following suggestions from Dair Grant. Also renamed the variable
748        "this" as "item" because it is a C++ keyword.
749    
750    45. Arranged for dftables to add
751    
752          #include "pcre_internal.h"
753    
754        to pcre_chartables.c because without it, gcc 4.x may remove the array
755        definition from the final binary if PCRE is built into a static library and
756        dead code stripping is activated.
757    
758    46. For an unanchored pattern, if a match attempt fails at the start of a
759        newline sequence, and the newline setting is CRLF or ANY, and the next two
760        characters are CRLF, advance by two characters instead of one.
761    
762    
763  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
764  ---------------------  ---------------------
765    

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