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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 256 by ph10, Wed Sep 19 08:57:53 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.4 10-Sep-07
5    ---------------------
6    
7    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
8        means that a class such as [\s] counted as "explicit reference to CR or
9        LF". That isn't really right - the whole point of the change was to try to
10        help when there was an actual mention of one of the two characters. So now
11        the change happens only if \r or \n (or a literal CR or LF) character is
12        encountered.
13    
14    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
15        of both had grown to the point where there were only 3 bits left.
16        Fortunately, there was spare space in the data structure, and so I have
17        moved the internal flags into a new 16-bit field to free up more option
18        bits.
19    
20    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
21        but did not set the internal JCHANGED flag - either of these is enough to
22        control the way the "get" function works - but the PCRE_INFO_JCHANGED
23        facility is supposed to tell if (?J) was ever used, so now (?J) at the
24        start sets both bits.
25    
26    4.  Added options (at build time, compile time, exec time) to change \R from
27        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
28    
29    5.  doc/pcresyntax.html was missing from the distribution.
30    
31    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
32        compatibility, even though it is no longer used.
33    
34    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
35        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
36        windows.h file is present (where different names are used).
37    
38    8.  Changed all #include <config.h> to #include "config.h". There were also
39        some further <pcre.h> cases that I changed to "pcre.h".
40    
41    9.  When pcregrep was used with the --colour option, it missed the line ending
42        sequence off the lines that it output.
43    
44    10. It was pointed out to me that arrays of string pointers cause lots of
45        relocations when a shared library is dynamically loaded. A technique of
46        using a single long string with a table of offsets can drastically reduce
47        these. I have refactored PCRE in four places to do this. The result is
48        dramatic:
49    
50          Originally:                          290
51          After changing UCP table:            187
52          After changing error message table:   43
53          After changing table of "verbs"       36
54          After changing table of Posix names   22
55    
56        Thanks to the folks working on Gregex for glib for this insight.
57    
58    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
59        unicode-properties was also set.
60    
61    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
62    
63    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
64        checked only for CRLF.
65    
66    14. Added casts to pcretest.c to avoid compiler warnings.
67    
68    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
69    
70    
71    Version 7.3 28-Aug-07
72    ---------------------
73    
74     1. In the rejigging of the build system that eventually resulted in 7.1, the
75        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
76        brackets there is not right, since it causes compilers to look for an
77        installed pcre.h, not the version that is in the source that is being
78        compiled (which of course may be different). I have changed it back to:
79    
80          #include "pcre.h"
81    
82        I have a vague recollection that the change was concerned with compiling in
83        different directories, but in the new build system, that is taken care of
84        by the VPATH setting the Makefile.
85    
86     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
87        when the subject happened to end in the byte 0x85 (e.g. if the last
88        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
89        characters but of course it shouldn't be taken as a newline when it is part
90        of another character. The bug was that, for an unlimited repeat of . in
91        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
92        characters when looking for a newline.
93    
94     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
95    
96     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
97        in debug output.
98    
99     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
100        long printing in the pcrecpp unittest when running under MinGW.
101    
102     6. ESC_K was left out of the EBCDIC table.
103    
104     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
105        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
106        limit also applies to "virtual nesting" when a pattern is recursive, and in
107        this case 1000 isn't so big. I have been able to remove this limit at the
108        expense of backing off one optimization in certain circumstances. Normally,
109        when pcre_exec() would call its internal match() function recursively and
110        immediately return the result unconditionally, it uses a "tail recursion"
111        feature to save stack. However, when a subpattern that can match an empty
112        string has an unlimited repetition quantifier, it no longer makes this
113        optimization. That gives it a stack frame in which to save the data for
114        checking that an empty string has been matched. Previously this was taken
115        from the 1000-entry workspace that had been reserved. So now there is no
116        explicit limit, but more stack is used.
117    
118     8. Applied Daniel's patches to solve problems with the import/export magic
119        syntax that is required for Windows, and which was going wrong for the
120        pcreposix and pcrecpp parts of the library. These were overlooked when this
121        problem was solved for the main library.
122    
123     9. There were some crude static tests to avoid integer overflow when computing
124        the size of patterns that contain repeated groups with explicit upper
125        limits. As the maximum quantifier is 65535, the maximum group length was
126        set at 30,000 so that the product of these two numbers did not overflow a
127        32-bit integer. However, it turns out that people want to use groups that
128        are longer than 30,000 bytes (though not repeat them that many times).
129        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
130        made it possible to implement the integer overflow checks in a much more
131        dynamic way, which I have now done. The artificial limitation on group
132        length has been removed - we now have only the limit on the total length of
133        the compiled pattern, which depends on the LINK_SIZE setting.
134    
135    10. Fixed a bug in the documentation for get/copy named substring when
136        duplicate names are permitted. If none of the named substrings are set, the
137        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
138        empty string.
139    
140    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
141        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
142        because the ] is interpreted as the first data character and the
143        terminating ] is not found. PCRE has been made compatible with Perl in this
144        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
145        cause memory overwriting.
146    
147    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
148        string has been matched (to stop an infinite loop). It was not recognizing
149        a conditional subpattern that could match an empty string if that
150        subpattern was within another subpattern. For example, it looped when
151        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
152        condition was not nested. This bug has been fixed.
153    
154    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
155        past the start of the subject in the presence of bytes with the top bit
156        set, for example "\x8aBCD".
157    
158    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
159        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
160    
161    14. Optimized (?!) to (*FAIL).
162    
163    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
164        This restricts code points to be within the range 0 to 0x10FFFF, excluding
165        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
166        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
167        does: it's just the validity check that is more restrictive.
168    
169    16. Inserted checks for integer overflows during escape sequence (backslash)
170        processing, and also fixed erroneous offset values for syntax errors during
171        backslash processing.
172    
173    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
174        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
175    
176    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
177        caused an overrun.
178    
179    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
180        something other than just ASCII characters) inside a group that had an
181        unlimited repeat caused a loop at compile time (while checking to see
182        whether the group could match an empty string).
183    
184    20. Debugging a pattern containing \p or \P could cause a crash. For example,
185        [\P{Any}] did so. (Error in the code for printing property names.)
186    
187    21. An orphan \E inside a character class could cause a crash.
188    
189    22. A repeated capturing bracket such as (A)? could cause a wild memory
190        reference during compilation.
191    
192    23. There are several functions in pcre_compile() that scan along a compiled
193        expression for various reasons (e.g. to see if it's fixed length for look
194        behind). There were bugs in these functions when a repeated \p or \P was
195        present in the pattern. These operators have additional parameters compared
196        with \d, etc, and these were not being taken into account when moving along
197        the compiled data. Specifically:
198    
199        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
200            length.
201    
202        (b) An item such as \pL+ within a repeated group could cause crashes or
203            loops.
204    
205        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
206            "reference to non-existent subpattern" error.
207    
208        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
209    
210    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
211        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
212    
213    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
214    
215    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
216        character were causing crashes (broken optimization).
217    
218    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
219        \p or \P) caused a compile-time loop.
220    
221    28. More problems have arisen in unanchored patterns when CRLF is a valid line
222        break. For example, the unstudied pattern [\r\n]A does not match the string
223        "\r\nA" because change 7.0/46 below moves the current point on by two
224        characters after failing to match at the start. However, the pattern \nA
225        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
226        the same is true. There doesn't seem any very clean way out of this, but
227        what I have chosen to do makes the common cases work: PCRE now takes note
228        of whether there can be an explicit match for \r or \n anywhere in the
229        pattern, and if so, 7.0/46 no longer applies. As part of this change,
230        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
231        pattern has explicit CR or LF references.
232    
233    29. Added (*CR) etc for changing newline setting at start of pattern.
234    
235    
236    Version 7.2 19-Jun-07
237    ---------------------
238    
239     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
240        which is apparently normally available under Windows.
241    
242     2. Re-jig the pcregrep tests with different newline settings in an attempt
243        to make them independent of the local environment's newline setting.
244    
245     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
246    
247     4. Some of the "internals" tests were previously cut out when the link size
248        was not 2, because the output contained actual offsets. The recent new
249        "Z" feature of pcretest means that these can be cut out, making the tests
250        usable with all link sizes.
251    
252     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
253        stack recursion. This gives a massive performance boost under BSD, but just
254        a small improvement under Linux. However, it saves one field in the frame
255        in all cases.
256    
257     6. Added more features from the forthcoming Perl 5.10:
258    
259        (a) (?-n) (where n is a string of digits) is a relative subroutine or
260            recursion call. It refers to the nth most recently opened parentheses.
261    
262        (b) (?+n) is also a relative subroutine call; it refers to the nth next
263            to be opened parentheses.
264    
265        (c) Conditions that refer to capturing parentheses can be specified
266            relatively, for example, (?(-2)... or (?(+3)...
267    
268        (d) \K resets the start of the current match so that everything before
269            is not part of it.
270    
271        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
272    
273        (f) \g{name} is another synonym - part of Perl 5.10's unification of
274            reference syntax.
275    
276        (g) (?| introduces a group in which the numbering of parentheses in each
277            alternative starts with the same number.
278    
279        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
280    
281     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
282        PCRE_INFO_JCHANGED.
283    
284     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
285        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
286        for detecting groups that can match an empty string.
287    
288     9. A pattern with a very large number of alternatives (more than several
289        hundred) was running out of internal workspace during the pre-compile
290        phase, where pcre_compile() figures out how much memory will be needed. A
291        bit of new cunning has reduced the workspace needed for groups with
292        alternatives. The 1000-alternative test pattern now uses 12 bytes of
293        workspace instead of running out of the 4096 that are available.
294    
295    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
296    
297    11. Applied patch from Google to remove an optimization that didn't quite work.
298        The report of the bug said:
299    
300          pcrecpp::RE("a*").FullMatch("aaa") matches, while
301          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
302          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
303    
304    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
305        it matched the wrong number of bytes.
306    
307    
308    Version 7.1 24-Apr-07
309    ---------------------
310    
311     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
312        that is more "standard", making use of automake and other Autotools. There
313        is some re-arrangement of the files and adjustment of comments consequent
314        on this.
315    
316     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
317        for recursive directory scanning broke on some systems because the files
318        are not scanned in any specific order and on different systems the order
319        was different. A call to "sort" has been inserted into RunGrepTest for the
320        approprate test as a short-term fix. In the longer term there may be an
321        alternative.
322    
323     3. I had an email from Eric Raymond about problems translating some of PCRE's
324        man pages to HTML (despite the fact that I distribute HTML pages, some
325        people do their own conversions for various reasons). The problems
326        concerned the use of low-level troff macros .br and .in. I have therefore
327        removed all such uses from the man pages (some were redundant, some could
328        be replaced by .nf/.fi pairs). The 132html script that I use to generate
329        HTML has been updated to handle .nf/.fi and to complain if it encounters
330        .br or .in.
331    
332     4. Updated comments in configure.ac that get placed in config.h.in and also
333        arranged for config.h to be included in the distribution, with the name
334        config.h.generic, for the benefit of those who have to compile without
335        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
336    
337     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
338        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
339        makevp.bat for the current PCRE, using the additional files
340        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
341    
342     6. A Windows user reported a minor discrepancy with test 2, which turned out
343        to be caused by a trailing space on an input line that had got lost in his
344        copy. The trailing space was an accident, so I've just removed it.
345    
346     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
347        that is needed.
348    
349     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
350        as "const" (a) because they are and (b) because it helps the PHP
351        maintainers who have recently made a script to detect big data structures
352        in the php code that should be moved to the .rodata section. I remembered
353        to update Builducptable as well, so it won't revert if ucptable.h is ever
354        re-created.
355    
356     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
357        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
358        order to be able to cut out the UTF-8 tables in the latter when UTF-8
359        support is not required. This saves 1.5-2K of code, which is important in
360        some applications.
361    
362        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
363        so as not to refer to the tables, even though these functions will never be
364        called when UTF-8 support is disabled. Otherwise there are problems with a
365        shared library.
366    
367    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
368    
369        (a) It was defining its arguments as char * instead of void *.
370    
371        (b) It was assuming that all moves were upwards in memory; this was true
372            a long time ago when I wrote it, but is no longer the case.
373    
374        The emulated memove() is provided for those environments that have neither
375        memmove() nor bcopy(). I didn't think anyone used it these days, but that
376        is clearly not the case, as these two bugs were recently reported.
377    
378    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
379        and Detrail to create the HTML documentation, the .txt form of the man
380        pages, and it removes trailing spaces from listed files. It also creates
381        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
382        case, it wraps all the #defines with #ifndefs. This script should be run
383        before "make dist".
384    
385    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
386        with Unicode property support.
387    
388        (a) For a maximizing quantifier, if the two different cases of the
389            character were of different lengths in their UTF-8 codings (there are
390            some cases like this - I found 11), and the matching function had to
391            back up over a mixture of the two cases, it incorrectly assumed they
392            were both the same length.
393    
394        (b) When PCRE was configured to use the heap rather than the stack for
395            recursion during matching, it was not correctly preserving the data for
396            the other case of a UTF-8 character when checking ahead for a match
397            while processing a minimizing repeat. If the check also involved
398            matching a wide character, but failed, corruption could cause an
399            erroneous result when trying to check for a repeat of the original
400            character.
401    
402    13. Some tidying changes to the testing mechanism:
403    
404        (a) The RunTest script now detects the internal link size and whether there
405            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
406            values substituted by "configure". (The RunGrepTest script already did
407            this for UTF-8.) The configure.ac script no longer substitutes the
408            relevant variables.
409    
410        (b) The debugging options /B and /D in pcretest show the compiled bytecode
411            with length and offset values. This means that the output is different
412            for different internal link sizes. Test 2 is skipped for link sizes
413            other than 2 because of this, bypassing the problem. Unfortunately,
414            there was also a test in test 3 (the locale tests) that used /B and
415            failed for link sizes other than 2. Rather than cut the whole test out,
416            I have added a new /Z option to pcretest that replaces the length and
417            offset values with spaces. This is now used to make test 3 independent
418            of link size. (Test 2 will be tidied up later.)
419    
420    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
421        segmentation fault instead of returning the appropriate error message.
422    
423    15. In multiline mode when the newline sequence was set to "any", the pattern
424        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
425        This doesn't seem right; it now treats the CRLF combination as the line
426        ending, and so does not match in that case. It's only a pattern such as ^$
427        that would hit this one: something like ^ABC$ would have failed after \r
428        and then tried again after \r\n.
429    
430    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
431        in an attempt to make files that differ only in their line terminators
432        compare equal. This works on Linux.
433    
434    17. Under certain error circumstances pcregrep might try to free random memory
435        as it exited. This is now fixed, thanks to valgrind.
436    
437    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
438        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
439        was because its rules for how to advance for /g after matching an empty
440        string at the end of a line did not allow for this case. They now check for
441        it specially.
442    
443    20. pcretest is supposed to handle patterns and data of any length, by
444        extending its buffers when necessary. It was getting this wrong when the
445        buffer for a data line had to be extended.
446    
447    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
448        CRLF as a newline sequence.
449    
450    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
451        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
452        I have nevertheless tidied it up.
453    
454    23. Added some casts to kill warnings from HP-UX ia64 compiler.
455    
456    24. Added a man page for pcre-config.
457    
458    
459    Version 7.0 19-Dec-06
460    ---------------------
461    
462     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
463        moving to gcc 4.1.1.
464    
465     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
466        sys/time.h, which is documented as needed for this function. It doesn't
467        seem to matter on Linux, but it showed up on some releases of OS X.
468    
469     3. It seems that there are systems where bytes whose values are greater than
470        127 match isprint() in the "C" locale. The "C" locale should be the
471        default when a C program starts up. In most systems, only ASCII printing
472        characters match isprint(). This difference caused the output from pcretest
473        to vary, making some of the tests fail. I have changed pcretest so that:
474    
475        (a) When it is outputting text in the compiled version of a pattern, bytes
476            other than 32-126 are always shown as hex escapes.
477    
478        (b) When it is outputting text that is a matched part of a subject string,
479            it does the same, unless a different locale has been set for the match
480            (using the /L modifier). In this case, it uses isprint() to decide.
481    
482     4. Fixed a major bug that caused incorrect computation of the amount of memory
483        required for a compiled pattern when options that changed within the
484        pattern affected the logic of the preliminary scan that determines the
485        length. The relevant options are -x, and -i in UTF-8 mode. The result was
486        that the computed length was too small. The symptoms of this bug were
487        either the PCRE error "internal error: code overflow" from pcre_compile(),
488        or a glibc crash with a message such as "pcretest: free(): invalid next
489        size (fast)". Examples of patterns that provoked this bug (shown in
490        pcretest format) are:
491    
492          /(?-x: )/x
493          /(?x)(?-x: \s*#\s*)/
494          /((?i)[\x{c0}])/8
495          /(?i:[\x{c0}])/8
496    
497        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
498        is now done differently.
499    
500     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
501        wrapper classes; (b) implement a new function in the C++ scanner that is
502        more efficient than the old way of doing things because it avoids levels of
503        recursion in the regex matching; (c) add a paragraph to the documentation
504        for the FullMatch() function.
505    
506     6. The escape sequence \n was being treated as whatever was defined as
507        "newline". Not only was this contrary to the documentation, which states
508        that \n is character 10 (hex 0A), but it also went horribly wrong when
509        "newline" was defined as CRLF. This has been fixed.
510    
511     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
512        was being set to -1 for the "end of line" case (supposedly a value that no
513        character can have). Though this value is never used (the check for end of
514        line is "zero bytes in current character"), it caused compiler complaints.
515        I've changed it to 0xffffffff.
516    
517     8. In pcre_version.c, the version string was being built by a sequence of
518        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
519        string (as it is for production releases) called a macro with an empty
520        argument. The C standard says the result of this is undefined. The gcc
521        compiler treats it as an empty string (which was what was wanted) but it is
522        reported that Visual C gives an error. The source has been hacked around to
523        avoid this problem.
524    
525     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
526        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
527        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
528        of them did).
529    
530    10. Originally, pcretest opened its input and output without "b"; then I was
531        told that "b" was needed in some environments, so it was added for release
532        5.0 to both the input and output. (It makes no difference on Unix-like
533        systems.) Later I was told that it is wrong for the input on Windows. I've
534        now abstracted the modes into two macros, to make it easier to fiddle with
535        them, and removed "b" from the input mode under Windows.
536    
537    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
538    
539    12. Added -help and --help to pcretest as an official way of being reminded
540        of the options.
541    
542    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
543        and pcrecpp.cc because they annoy compilers at high warning levels.
544    
545    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
546    
547    15. Fixed an occurrence of == in configure.ac that should have been = (shell
548        scripts are not C programs :-) and which was not noticed because it works
549        on Linux.
550    
551    16. pcretest is supposed to handle any length of pattern and data line (as one
552        line or as a continued sequence of lines) by extending its input buffer if
553        necessary. This feature was broken for very long pattern lines, leading to
554        a string of junk being passed to pcre_compile() if the pattern was longer
555        than about 50K.
556    
557    17. I have done a major re-factoring of the way pcre_compile() computes the
558        amount of memory needed for a compiled pattern. Previously, there was code
559        that made a preliminary scan of the pattern in order to do this. That was
560        OK when PCRE was new, but as the facilities have expanded, it has become
561        harder and harder to keep it in step with the real compile phase, and there
562        have been a number of bugs (see for example, 4 above). I have now found a
563        cunning way of running the real compile function in a "fake" mode that
564        enables it to compute how much memory it would need, while actually only
565        ever using a few hundred bytes of working memory and without too many
566        tests of the mode. This should make future maintenance and development
567        easier. A side effect of this work is that the limit of 200 on the nesting
568        depth of parentheses has been removed (though this was never a serious
569        limitation, I suspect). However, there is a downside: pcre_compile() now
570        runs more slowly than before (30% or more, depending on the pattern). I
571        hope this isn't a big issue. There is no effect on runtime performance.
572    
573    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
574        newline (only possible for the last line of a file) and it was a
575        pattern that set a locale (followed by /Lsomething), pcretest crashed.
576    
577    19. Added additional timing features to pcretest. (1) The -tm option now times
578        matching only, not compiling. (2) Both -t and -tm can be followed, as a
579        separate command line item, by a number that specifies the number of
580        repeats to use when timing. The default is 50000; this gives better
581        precision, but takes uncomfortably long for very large patterns.
582    
583    20. Extended pcre_study() to be more clever in cases where a branch of a
584        subpattern has no definite first character. For example, (a*|b*)[cd] would
585        previously give no result from pcre_study(). Now it recognizes that the
586        first character must be a, b, c, or d.
587    
588    21. There was an incorrect error "recursive call could loop indefinitely" if
589        a subpattern (or the entire pattern) that was being tested for matching an
590        empty string contained only one non-empty item after a nested subpattern.
591        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
592        incorrectly, because the \d was being skipped in the check.
593    
594    22. The pcretest program now has a new pattern option /B and a command line
595        option -b, which is equivalent to adding /B to every pattern. This causes
596        it to show the compiled bytecode, without the additional information that
597        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
598        is the same as /B/I).
599    
600    23. A new optimization is now able automatically to treat some sequences such
601        as a*b as a*+b. More specifically, if something simple (such as a character
602        or a simple class like \d) has an unlimited quantifier, and is followed by
603        something that cannot possibly match the quantified thing, the quantifier
604        is automatically "possessified".
605    
606    24. A recursive reference to a subpattern whose number was greater than 39
607        went wrong under certain circumstances in UTF-8 mode. This bug could also
608        have affected the operation of pcre_study().
609    
610    25. Realized that a little bit of performance could be had by replacing
611        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
612    
613    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
614    
615    27. Possessive quantifiers such as a++ were previously implemented by turning
616        them into atomic groups such as ($>a+). Now they have their own opcodes,
617        which improves performance. This includes the automatically created ones
618        from 23 above.
619    
620    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
621        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
622        the first matched character to be a colon. This applied both to named and
623        numbered groups.
624    
625    29. The ucpinternal.h header file was missing its idempotency #ifdef.
626    
627    30. I was sent a "project" file called libpcre.a.dev which I understand makes
628        building PCRE on Windows easier, so I have included it in the distribution.
629    
630    31. There is now a check in pcretest against a ridiculously large number being
631        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
632        loop, the loop is abandoned.
633    
634    32. Forward references to subpatterns in conditions such as (?(2)...) where
635        subpattern 2 is defined later cause pcre_compile() to search forwards in
636        the pattern for the relevant set of parentheses. This search went wrong
637        when there were unescaped parentheses in a character class, parentheses
638        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
639    
640    33. "Subroutine" calls and backreferences were previously restricted to
641        referencing subpatterns earlier in the regex. This restriction has now
642        been removed.
643    
644    34. Added a number of extra features that are going to be in Perl 5.10. On the
645        whole, these are just syntactic alternatives for features that PCRE had
646        previously implemented using the Python syntax or my own invention. The
647        other formats are all retained for compatibility.
648    
649        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
650            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
651            also .NET compatible.
652    
653        (b) A recursion or subroutine call to a named group can now be defined as
654            (?&name) as well as (?P>name).
655    
656        (c) A backreference to a named group can now be defined as \k<name> or
657            \k'name' as well as (?P=name). The new forms, as well as being in Perl
658            5.10, are also .NET compatible.
659    
660        (d) A conditional reference to a named group can now use the syntax
661            (?(<name>) or (?('name') as well as (?(name).
662    
663        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
664            groups (named and numbered) that are never evaluated inline, but can be
665            called as "subroutines" from elsewhere. In effect, the DEFINE condition
666            is always false. There may be only one alternative in such a group.
667    
668        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
669            as the simple (?(R). The condition is true only if the most recent
670            recursion is that of the given number or name. It does not search out
671            through the entire recursion stack.
672    
673        (g) The escape \gN or \g{N} has been added, where N is a positive or
674            negative number, specifying an absolute or relative reference.
675    
676    35. Tidied to get rid of some further signed/unsigned compiler warnings and
677        some "unreachable code" warnings.
678    
679    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
680        things, this adds five new scripts.
681    
682    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
683        There were also incompatibilities regarding the handling of \Q..\E inside
684        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
685        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
686    
687    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
688        matches an empty string, and forcibly breaks the loop. There were bugs in
689        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
690        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
691        separate and independent bugs (that affected different cases) have been
692        fixed.
693    
694    39. Refactored the code to abolish the use of different opcodes for small
695        capturing bracket numbers. This is a tidy that I avoided doing when I
696        removed the limit on the number of capturing brackets for 3.5 back in 2001.
697        The new approach is not only tidier, it makes it possible to reduce the
698        memory needed to fix the previous bug (38).
699    
700    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
701        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
702        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
703        mode.
704    
705    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
706        report.
707    
708    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
709        copy construction and assignment in the C++ wrapper.
710    
711    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
712        couple of bugs that could have given wrong results in the "--newline=crlf"
713        case.
714    
715    44. Added a number of casts and did some reorganization of signed/unsigned int
716        variables following suggestions from Dair Grant. Also renamed the variable
717        "this" as "item" because it is a C++ keyword.
718    
719    45. Arranged for dftables to add
720    
721          #include "pcre_internal.h"
722    
723        to pcre_chartables.c because without it, gcc 4.x may remove the array
724        definition from the final binary if PCRE is built into a static library and
725        dead code stripping is activated.
726    
727    46. For an unanchored pattern, if a match attempt fails at the start of a
728        newline sequence, and the newline setting is CRLF or ANY, and the next two
729        characters are CRLF, advance by two characters instead of one.
730    
731    
732  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
733  ---------------------  ---------------------
734    

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