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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 12-Mar-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files
36        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
65        (a) It was defining its arguments as char * instead of void *.
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
98    13. Some tidying changes to the testing mechanism:
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
119    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string did not allow for this case. They now check for it specially.
139    Version 7.0 19-Dec-06
140    ---------------------
142     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
143        moving to gcc 4.1.1.
145     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
146        sys/time.h, which is documented as needed for this function. It doesn't
147        seem to matter on Linux, but it showed up on some releases of OS X.
149     3. It seems that there are systems where bytes whose values are greater than
150        127 match isprint() in the "C" locale. The "C" locale should be the
151        default when a C program starts up. In most systems, only ASCII printing
152        characters match isprint(). This difference caused the output from pcretest
153        to vary, making some of the tests fail. I have changed pcretest so that:
155        (a) When it is outputting text in the compiled version of a pattern, bytes
156            other than 32-126 are always shown as hex escapes.
158        (b) When it is outputting text that is a matched part of a subject string,
159            it does the same, unless a different locale has been set for the match
160            (using the /L modifier). In this case, it uses isprint() to decide.
162     4. Fixed a major bug that caused incorrect computation of the amount of memory
163        required for a compiled pattern when options that changed within the
164        pattern affected the logic of the preliminary scan that determines the
165        length. The relevant options are -x, and -i in UTF-8 mode. The result was
166        that the computed length was too small. The symptoms of this bug were
167        either the PCRE error "internal error: code overflow" from pcre_compile(),
168        or a glibc crash with a message such as "pcretest: free(): invalid next
169        size (fast)". Examples of patterns that provoked this bug (shown in
170        pcretest format) are:
172          /(?-x: )/x
173          /(?x)(?-x: \s*#\s*)/
174          /((?i)[\x{c0}])/8
175          /(?i:[\x{c0}])/8
177        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
178        is now done differently.
180     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
181        wrapper classes; (b) implement a new function in the C++ scanner that is
182        more efficient than the old way of doing things because it avoids levels of
183        recursion in the regex matching; (c) add a paragraph to the documentation
184        for the FullMatch() function.
186     6. The escape sequence \n was being treated as whatever was defined as
187        "newline". Not only was this contrary to the documentation, which states
188        that \n is character 10 (hex 0A), but it also went horribly wrong when
189        "newline" was defined as CRLF. This has been fixed.
191     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
192        was being set to -1 for the "end of line" case (supposedly a value that no
193        character can have). Though this value is never used (the check for end of
194        line is "zero bytes in current character"), it caused compiler complaints.
195        I've changed it to 0xffffffff.
197     8. In pcre_version.c, the version string was being built by a sequence of
198        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
199        string (as it is for production releases) called a macro with an empty
200        argument. The C standard says the result of this is undefined. The gcc
201        compiler treats it as an empty string (which was what was wanted) but it is
202        reported that Visual C gives an error. The source has been hacked around to
203        avoid this problem.
205     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
206        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
207        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
208        of them did).
210    10. Originally, pcretest opened its input and output without "b"; then I was
211        told that "b" was needed in some environments, so it was added for release
212        5.0 to both the input and output. (It makes no difference on Unix-like
213        systems.) Later I was told that it is wrong for the input on Windows. I've
214        now abstracted the modes into two macros, to make it easier to fiddle with
215        them, and removed "b" from the input mode under Windows.
217    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
219    12. Added -help and --help to pcretest as an official way of being reminded
220        of the options.
222    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
223        and pcrecpp.cc because they annoy compilers at high warning levels.
225    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
227    15. Fixed an occurrence of == in configure.ac that should have been = (shell
228        scripts are not C programs :-) and which was not noticed because it works
229        on Linux.
231    16. pcretest is supposed to handle any length of pattern and data line (as one
232        line or as a continued sequence of lines) by extending its input buffer if
233        necessary. This feature was broken for very long pattern lines, leading to
234        a string of junk being passed to pcre_compile() if the pattern was longer
235        than about 50K.
237    17. I have done a major re-factoring of the way pcre_compile() computes the
238        amount of memory needed for a compiled pattern. Previously, there was code
239        that made a preliminary scan of the pattern in order to do this. That was
240        OK when PCRE was new, but as the facilities have expanded, it has become
241        harder and harder to keep it in step with the real compile phase, and there
242        have been a number of bugs (see for example, 4 above). I have now found a
243        cunning way of running the real compile function in a "fake" mode that
244        enables it to compute how much memory it would need, while actually only
245        ever using a few hundred bytes of working memory and without too many
246        tests of the mode. This should make future maintenance and development
247        easier. A side effect of this work is that the limit of 200 on the nesting
248        depth of parentheses has been removed (though this was never a serious
249        limitation, I suspect). However, there is a downside: pcre_compile() now
250        runs more slowly than before (30% or more, depending on the pattern). I
251        hope this isn't a big issue. There is no effect on runtime performance.
253    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
254        newline (only possible for the last line of a file) and it was a
255        pattern that set a locale (followed by /Lsomething), pcretest crashed.
257    19. Added additional timing features to pcretest. (1) The -tm option now times
258        matching only, not compiling. (2) Both -t and -tm can be followed, as a
259        separate command line item, by a number that specifies the number of
260        repeats to use when timing. The default is 50000; this gives better
261        precision, but takes uncomfortably long for very large patterns.
263    20. Extended pcre_study() to be more clever in cases where a branch of a
264        subpattern has no definite first character. For example, (a*|b*)[cd] would
265        previously give no result from pcre_study(). Now it recognizes that the
266        first character must be a, b, c, or d.
268    21. There was an incorrect error "recursive call could loop indefinitely" if
269        a subpattern (or the entire pattern) that was being tested for matching an
270        empty string contained only one non-empty item after a nested subpattern.
271        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
272        incorrectly, because the \d was being skipped in the check.
274    22. The pcretest program now has a new pattern option /B and a command line
275        option -b, which is equivalent to adding /B to every pattern. This causes
276        it to show the compiled bytecode, without the additional information that
277        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
278        is the same as /B/I).
280    23. A new optimization is now able automatically to treat some sequences such
281        as a*b as a*+b. More specifically, if something simple (such as a character
282        or a simple class like \d) has an unlimited quantifier, and is followed by
283        something that cannot possibly match the quantified thing, the quantifier
284        is automatically "possessified".
286    24. A recursive reference to a subpattern whose number was greater than 39
287        went wrong under certain circumstances in UTF-8 mode. This bug could also
288        have affected the operation of pcre_study().
290    25. Realized that a little bit of performance could be had by replacing
291        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
293    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
295    27. Possessive quantifiers such as a++ were previously implemented by turning
296        them into atomic groups such as ($>a+). Now they have their own opcodes,
297        which improves performance. This includes the automatically created ones
298        from 23 above.
300    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
301        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
302        the first matched character to be a colon. This applied both to named and
303        numbered groups.
305    29. The ucpinternal.h header file was missing its idempotency #ifdef.
307    30. I was sent a "project" file called libpcre.a.dev which I understand makes
308        building PCRE on Windows easier, so I have included it in the distribution.
310    31. There is now a check in pcretest against a ridiculously large number being
311        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
312        loop, the loop is abandoned.
314    32. Forward references to subpatterns in conditions such as (?(2)...) where
315        subpattern 2 is defined later cause pcre_compile() to search forwards in
316        the pattern for the relevant set of parentheses. This search went wrong
317        when there were unescaped parentheses in a character class, parentheses
318        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
320    33. "Subroutine" calls and backreferences were previously restricted to
321        referencing subpatterns earlier in the regex. This restriction has now
322        been removed.
324    34. Added a number of extra features that are going to be in Perl 5.10. On the
325        whole, these are just syntactic alternatives for features that PCRE had
326        previously implemented using the Python syntax or my own invention. The
327        other formats are all retained for compatibility.
329        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
330            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
331            also .NET compatible.
333        (b) A recursion or subroutine call to a named group can now be defined as
334            (?&name) as well as (?P>name).
336        (c) A backreference to a named group can now be defined as \k<name> or
337            \k'name' as well as (?P=name). The new forms, as well as being in Perl
338            5.10, are also .NET compatible.
340        (d) A conditional reference to a named group can now use the syntax
341            (?(<name>) or (?('name') as well as (?(name).
343        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
344            groups (named and numbered) that are never evaluated inline, but can be
345            called as "subroutines" from elsewhere. In effect, the DEFINE condition
346            is always false. There may be only one alternative in such a group.
348        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
349            as the simple (?(R). The condition is true only if the most recent
350            recursion is that of the given number or name. It does not search out
351            through the entire recursion stack.
353        (g) The escape \gN or \g{N} has been added, where N is a positive or
354            negative number, specifying an absolute or relative reference.
356    35. Tidied to get rid of some further signed/unsigned compiler warnings and
357        some "unreachable code" warnings.
359    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
360        things, this adds five new scripts.
362    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
363        There were also incompatibilities regarding the handling of \Q..\E inside
364        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
365        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
367    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
368        matches an empty string, and forcibly breaks the loop. There were bugs in
369        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
370        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
371        separate and independent bugs (that affected different cases) have been
372        fixed.
374    39. Refactored the code to abolish the use of different opcodes for small
375        capturing bracket numbers. This is a tidy that I avoided doing when I
376        removed the limit on the number of capturing brackets for 3.5 back in 2001.
377        The new approach is not only tidier, it makes it possible to reduce the
378        memory needed to fix the previous bug (38).
380    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
381        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
382        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
383        mode.
385    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
386        report.
388    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
389        copy construction and assignment in the C++ wrapper.
391    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
392        couple of bugs that could have given wrong results in the "--newline=crlf"
393        case.
395    44. Added a number of casts and did some reorganization of signed/unsigned int
396        variables following suggestions from Dair Grant. Also renamed the variable
397        "this" as "item" because it is a C++ keyword.
399    45. Arranged for dftables to add
401          #include "pcre_internal.h"
403        to pcre_chartables.c because without it, gcc 4.x may remove the array
404        definition from the final binary if PCRE is built into a static library and
405        dead code stripping is activated.
407    46. For an unanchored pattern, if a match attempt fails at the start of a
408        newline sequence, and the newline setting is CRLF or ANY, and the next two
409        characters are CRLF, advance by two characters instead of one.
412    Version 6.7 04-Jul-06
413    ---------------------
415     1. In order to handle tests when input lines are enormously long, pcretest has
416        been re-factored so that it automatically extends its buffers when
417        necessary. The code is crude, but this _is_ just a test program. The
418        default size has been increased from 32K to 50K.
420     2. The code in pcre_study() was using the value of the re argument before
421        testing it for NULL. (Of course, in any sensible call of the function, it
422        won't be NULL.)
424     3. The memmove() emulation function in pcre_internal.h, which is used on
425        systems that lack both memmove() and bcopy() - that is, hardly ever -
426        was missing a "static" storage class specifier.
428     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
429        containing an extended class (one that cannot be represented by a bitmap
430        because it contains high-valued characters or Unicode property items, e.g.
431        [\pZ]). Almost always one would set UTF-8 mode when processing such a
432        pattern, but PCRE should not loop if you do not (it no longer does).
433        [Detail: two cases were found: (a) a repeated subpattern containing an
434        extended class; (b) a recursive reference to a subpattern that followed a
435        previous extended class. It wasn't skipping over the extended class
436        correctly when UTF-8 mode was not set.]
438     5. A negated single-character class was not being recognized as fixed-length
439        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
440        compile error "lookbehind assertion is not fixed length".
442     6. The RunPerlTest auxiliary script was showing an unexpected difference
443        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
444        write a Perl script that can interpret lines of an input file either as
445        byte characters or as UTF-8, which is what "perltest" was being required to
446        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
447        can't do is switch easily at run time between having the "use utf8;" pragma
448        or not. In the end, I fudged it by using the RunPerlTest script to insert
449        "use utf8;" explicitly for the UTF-8 tests.
451     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
452        the end of the subject string, contrary to the documentation and to what
453        Perl does. This was true of both matching functions. Now it matches only at
454        the start of the subject and immediately after *internal* newlines.
456     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
457        a pointer to an int instead of a pointer to an unsigned long int. This
458        caused problems on 64-bit systems.
460     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
461        instance of the 'standard' template library not being so standard".
463    10. There was no check on the number of named subpatterns nor the maximum
464        length of a subpattern name. The product of these values is used to compute
465        the size of the memory block for a compiled pattern. By supplying a very
466        long subpattern name and a large number of named subpatterns, the size
467        computation could be caused to overflow. This is now prevented by limiting
468        the length of names to 32 characters, and the number of named subpatterns
469        to 10,000.
471    11. Subpatterns that are repeated with specific counts have to be replicated in
472        the compiled pattern. The size of memory for this was computed from the
473        length of the subpattern and the repeat count. The latter is limited to
474        65535, but there was no limit on the former, meaning that integer overflow
475        could in principle occur. The compiled length of a repeated subpattern is
476        now limited to 30,000 bytes in order to prevent this.
478    12. Added the optional facility to have named substrings with the same name.
480    13. Added the ability to use a named substring as a condition, using the
481        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
482        are numbers (not recommended). Forward references are permitted.
484    14. Added forward references in named backreferences (if you see what I mean).
486    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
487        pattern could run off the end of the subject. For example, the pattern
488        "(?s)(.{1,5})"8 did this with the subject "ab".
490    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
491        PCRE_CASELESS was set when matching characters that were quantified with ?
492        or *.
494    17. A character class other than a single negated character that had a minimum
495        but no maximum quantifier - for example [ab]{6,} - was not handled
496        correctly by pce_dfa_exec(). It would match only one character.
498    18. A valid (though odd) pattern that looked like a POSIX character
499        class but used an invalid character after [ (for example [[,abc,]]) caused
500        pcre_compile() to give the error "Failed: internal error: code overflow" or
501        in some cases to crash with a glibc free() error. This could even happen if
502        the pattern terminated after [[ but there just happened to be a sequence of
503        letters, a binary zero, and a closing ] in the memory that followed.
505    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
506        over the years. Originally (before any Unicode support), just the bottom 8
507        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
508        output from "man perlunicode" includes this:
510          The regular expression compiler produces polymorphic opcodes.  That
511          is, the pattern adapts to the data and automatically switches to
512          the Unicode character scheme when presented with Unicode data--or
513          instead uses a traditional byte scheme when presented with byte
514          data.
516        Sadly, a wide octal escape does not cause a switch, and in a string with
517        no other multibyte characters, these octal escapes are treated as before.
518        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
519        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
520        Unicode string.
522        I have not perpetrated such confusion in PCRE. Up till now, it took just
523        the bottom 8 bits, as in old Perl. I have now made octal escapes with
524        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
525        translate to the appropriate multibyte character.
527    29. Applied some refactoring to reduce the number of warnings from Microsoft
528        and Borland compilers. This has included removing the fudge introduced
529        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
530        a warning about an unused variable.
532    21. PCRE has not included VT (character 0x0b) in the set of whitespace
533        characters since release 4.0, because Perl (from release 5.004) does not.
534        [Or at least, is documented not to: some releases seem to be in conflict
535        with the documentation.] However, when a pattern was studied with
536        pcre_study() and all its branches started with \s, PCRE still included VT
537        as a possible starting character. Of course, this did no harm; it just
538        caused an unnecessary match attempt.
540    22. Removed a now-redundant internal flag bit that recorded the fact that case
541        dependency changed within the pattern. This was once needed for "required
542        byte" processing, but is no longer used. This recovers a now-scarce options
543        bit. Also moved the least significant internal flag bit to the most-
544        significant bit of the word, which was not previously used (hangover from
545        the days when it was an int rather than a uint) to free up another bit for
546        the future.
548    23. Added support for CRLF line endings as well as CR and LF. As well as the
549        default being selectable at build time, it can now be changed at runtime
550        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
551        specify that it is scanning data with non-default line endings.
553    24. Changed the definition of CXXLINK to make it agree with the definition of
554        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
556    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
557        recursions. This makes a big different to stack usage for some patterns.
559    26. If a subpattern containing a named recursion or subroutine reference such
560        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
561        the space required for the compiled pattern went wrong and gave too small a
562        value. Depending on the environment, this could lead to "Failed: internal
563        error: code overflow at offset 49" or "glibc detected double free or
564        corruption" errors.
566    27. Applied patches from Google (a) to support the new newline modes and (b) to
567        advance over multibyte UTF-8 characters in GlobalReplace.
569    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
570        difference for some implementation of PCRE in some Windows version.
572    29. Added some extra testing facilities to pcretest:
574        \q<number>   in a data line sets the "match limit" value
575        \Q<number>   in a data line sets the "match recursion limt" value
576        -S <number>  sets the stack size, where <number> is in megabytes
578        The -S option isn't available for Windows.
581    Version 6.6 06-Feb-06
582    ---------------------
584     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
585        in pcreposix.h. I have copied the definition from pcre.h.
587     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
588        because pcre.h is no longer a built file.
590     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
591        not normally included in the compiled code.
594    Version 6.5 01-Feb-06
595    ---------------------
597     1. When using the partial match feature with pcre_dfa_exec(), it was not
598        anchoring the second and subsequent partial matches at the new starting
599        point. This could lead to incorrect results. For example, with the pattern
600        /1234/, partially matching against "123" and then "a4" gave a match.
602     2. Changes to pcregrep:
604        (a) All non-match returns from pcre_exec() were being treated as failures
605            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
606            error message is output. Some extra information is given for the
607            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
608            probably the only errors that are likely to be caused by users (by
609            specifying a regex that has nested indefinite repeats, for instance).
610            If there are more than 20 of these errors, pcregrep is abandoned.
612        (b) A binary zero was treated as data while matching, but terminated the
613            output line if it was written out. This has been fixed: binary zeroes
614            are now no different to any other data bytes.
616        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
617            used to set a locale for matching. The --locale=xxxx long option has
618            been added (no short equivalent) to specify a locale explicitly on the
619            pcregrep command, overriding the environment variables.
621        (d) When -B was used with -n, some line numbers in the output were one less
622            than they should have been.
624        (e) Added the -o (--only-matching) option.
626        (f) If -A or -C was used with -c (count only), some lines of context were
627            accidentally printed for the final match.
629        (g) Added the -H (--with-filename) option.
631        (h) The combination of options -rh failed to suppress file names for files
632            that were found from directory arguments.
634        (i) Added the -D (--devices) and -d (--directories) options.
636        (j) Added the -F (--fixed-strings) option.
638        (k) Allow "-" to be used as a file name for -f as well as for a data file.
640        (l) Added the --colo(u)r option.
642        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
643            is not present by default.
645     3. A nasty bug was discovered in the handling of recursive patterns, that is,
646        items such as (?R) or (?1), when the recursion could match a number of
647        alternatives. If it matched one of the alternatives, but subsequently,
648        outside the recursion, there was a failure, the code tried to back up into
649        the recursion. However, because of the way PCRE is implemented, this is not
650        possible, and the result was an incorrect result from the match.
652        In order to prevent this happening, the specification of recursion has
653        been changed so that all such subpatterns are automatically treated as
654        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
656     4. I had overlooked the fact that, in some locales, there are characters for
657        which isalpha() is true but neither isupper() nor islower() are true. In
658        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
659        and ordfeminine) are like this. This affected the treatment of \w and \W
660        when they appeared in character classes, but not when they appeared outside
661        a character class. The bit map for "word" characters is now created
662        separately from the results of isalnum() instead of just taking it from the
663        upper, lower, and digit maps. (Plus the underscore character, of course.)
665     5. The above bug also affected the handling of POSIX character classes such as
666        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
667        permanent tables. Instead, the bit maps for such a class were previously
668        created as the appropriate unions of the upper, lower, and digit bitmaps.
669        Now they are created by subtraction from the [[:word:]] class, which has
670        its own bitmap.
672     6. The [[:blank:]] character class matches horizontal, but not vertical space.
673        It is created by subtracting the vertical space characters (\x09, \x0a,
674        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
675        subtraction was done in the overall bitmap for a character class, meaning
676        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
677        be recognized. This bug has been fixed.
679     7. Patches from the folks at Google:
681          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
682          real life, but is still worth protecting against".
684          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
685          regular expressions".
687          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
688          have it.
690          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
691          "configure" and the latter not, in order to fix a problem somebody had
692          with compiling the Arg class on HP-UX.
694          (e) Improve the error-handling of the C++ wrapper a little bit.
696          (f) New tests for checking recursion limiting.
698     8. The pcre_memmove() function, which is used only if the environment does not
699        have a standard memmove() function (and is therefore rarely compiled),
700        contained two bugs: (a) use of int instead of size_t, and (b) it was not
701        returning a result (though PCRE never actually uses the result).
703     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
704        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
705        returned instead of calling malloc() with an overflowing number that would
706        most likely cause subsequent chaos.
708    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
710    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
711        with this option is matched, the nmatch and pmatch options of regexec() are
712        ignored.
714    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
715        provided in case anyone wants to the the POSIX interface with UTF-8
716        strings.
718    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
719        C++ linking (needed for some HP-UX environments).
721    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
722        (unused parameter) and in the pcre_printint() function (omitted "default"
723        switch label when the default is to do nothing).
725    15. Added some code to make it possible, when PCRE is compiled as a C++
726        library, to replace subject pointers for pcre_exec() with a smart pointer
727        class, thus making it possible to process discontinuous strings.
729    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
730        much the same function. They were added by different people who were trying
731        to make PCRE easy to compile on non-Unix systems. It has been suggested
732        that PCRE_EXPORT be abolished now that there is more automatic apparatus
733        for compiling on Windows systems. I have therefore replaced it with
734        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
735        defaults to "extern" for C or "extern C" for C++, which works fine on
736        Unix-like systems. It is now possible to override the value of PCRE_DATA_
737        SCOPE with something explicit in config.h. In addition:
739        (a) pcreposix.h still had just "extern" instead of either of these macros;
740            I have replaced it with PCRE_DATA_SCOPE.
742        (b) Functions such as _pcre_xclass(), which are internal to the library,
743            but external in the C sense, all had PCRE_EXPORT in their definitions.
744            This is apparently wrong for the Windows case, so I have removed it.
745            (It makes no difference on Unix-like systems.)
747    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
748        of recursive calls to match(). This is different to MATCH_LIMIT because
749        that limits the total number of calls to match(), not all of which increase
750        the depth of recursion. Limiting the recursion depth limits the amount of
751        stack (or heap if NO_RECURSE is set) that is used. The default can be set
752        when PCRE is compiled, and changed at run time. A patch from Google adds
753        this functionality to the C++ interface.
755    18. Changes to the handling of Unicode character properties:
757        (a) Updated the table to Unicode 4.1.0.
759        (b) Recognize characters that are not in the table as "Cn" (undefined).
761        (c) I revised the way the table is implemented to a much improved format
762            which includes recognition of ranges. It now supports the ranges that
763            are defined in UnicodeData.txt, and it also amalgamates other
764            characters into ranges. This has reduced the number of entries in the
765            table from around 16,000 to around 3,000, thus reducing its size
766            considerably. I realized I did not need to use a tree structure after
767            all - a binary chop search is just as efficient. Having reduced the
768            number of entries, I extended their size from 6 bytes to 8 bytes to
769            allow for more data.
771        (d) Added support for Unicode script names via properties such as \p{Han}.
773    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
774        matching that character.
776    20. When matching a repeated Unicode property with a minimum greater than zero,
777        (for example \pL{2,}), PCRE could look past the end of the subject if it
778        reached it while seeking the minimum number of characters. This could
779        happen only if some of the characters were more than one byte long, because
780        there is a check for at least the minimum number of bytes.
782    21. Refactored the implementation of \p and \P so as to be more general, to
783        allow for more different types of property in future. This has changed the
784        compiled form incompatibly. Anybody with saved compiled patterns that use
785        \p or \P will have to recompile them.
787    22. Added "Any" and "L&" to the supported property types.
789    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
790        but give a compile time error if the value is greater than 0xff.
792    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
793        accidentally not being installed or uninstalled.
795    25. The pcre.h file was built from pcre.h.in, but the only changes that were
796        made were to insert the current release number. This seemed silly, because
797        it made things harder for people building PCRE on systems that don't run
798        "configure". I have turned pcre.h into a distributed file, no longer built
799        by "configure", with the version identification directly included. There is
800        no longer a pcre.h.in file.
802        However, this change necessitated a change to the pcre-config script as
803        well. It is built from pcre-config.in, and one of the substitutions was the
804        release number. I have updated configure.ac so that ./configure now finds
805        the release number by grepping pcre.h.
807    26. Added the ability to run the tests under valgrind.
810    Version 6.4 05-Sep-05
811    ---------------------
813     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
814        "--" to be printed when multiple files were scanned, even when none of the
815        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
816        consider it to be a bug, and have restored the previous behaviour.
818     2. A couple of code tidies to get rid of compiler warnings.
820     3. The pcretest program used to cheat by referring to symbols in the library
821        whose names begin with _pcre_. These are internal symbols that are not
822        really supposed to be visible externally, and in some environments it is
823        possible to suppress them. The cheating is now confined to including
824        certain files from the library's source, which is a bit cleaner.
826     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
827        file's purpose clearer.
829     5. Reorganized pcre_ucp_findchar().
832    Version 6.3 15-Aug-05
833    ---------------------
835     1. The file libpcre.pc.in did not have general read permission in the tarball.
837     2. There were some problems when building without C++ support:
839        (a) If C++ support was not built, "make install" and "make test" still
840            tried to test it.
842        (b) There were problems when the value of CXX was explicitly set. Some
843            changes have been made to try to fix these, and ...
845        (c) --disable-cpp can now be used to explicitly disable C++ support.
847        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
848            backslash in a target when C++ was disabled. This confuses some
849            versions of "make", apparently. Using an intermediate variable solves
850            this. (Same for CPP_LOBJ.)
852     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
853        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
854        necessary on certain architectures.
856     4. Added a setting of -export-symbols-regex to the link command to remove
857        those symbols that are exported in the C sense, but actually are local
858        within the library, and not documented. Their names all begin with
859        "_pcre_". This is not a perfect job, because (a) we have to except some
860        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
861        available (and never for static libraries). I have made a note to try to
862        find a way round (a) in the future.
865    Version 6.2 01-Aug-05
866    ---------------------
868     1. There was no test for integer overflow of quantifier values. A construction
869        such as {1111111111111111} would give undefined results. What is worse, if
870        a minimum quantifier for a parenthesized subpattern overflowed and became
871        negative, the calculation of the memory size went wrong. This could have
872        led to memory overwriting.
874     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
876     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
877        operating environments where this matters.
879     4. Applied Giuseppe Maxia's patch to add additional features for controlling
880        PCRE options from within the C++ wrapper.
882     5. Named capturing subpatterns were not being correctly counted when a pattern
883        was compiled. This caused two problems: (a) If there were more than 100
884        such subpatterns, the calculation of the memory needed for the whole
885        compiled pattern went wrong, leading to an overflow error. (b) Numerical
886        back references of the form \12, where the number was greater than 9, were
887        not recognized as back references, even though there were sufficient
888        previous subpatterns.
890     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
891        versions of gcc, e.g. 2.95.4.
894    Version 6.1 21-Jun-05
895    ---------------------
897     1. There was one reference to the variable "posix" in pcretest.c that was not
898        surrounded by "#if !defined NOPOSIX".
900     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
901        the cross-check on the old pcre_info() function, for the benefit of the
902        cut-down version of PCRE that is currently imported into Exim.
904     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
905        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
906        patterns that start (?i) but I don't think that matters. The use of (?i) is
907        just an example; this all applies to the other options as well.
909     4. Since libtool seems to echo the compile commands it is issuing, the output
910        from "make" can be reduced a bit by putting "@" in front of each libtool
911        compile command.
913     5. Patch from the folks at Google for configure.in to be a bit more thorough
914        in checking for a suitable C++ installation before trying to compile the
915        C++ stuff. This should fix a reported problem when a compiler was present,
916        but no suitable headers.
918     6. The man pages all had just "PCRE" as their title. I have changed them to
919        be the relevant file name. I have also arranged that these names are
920        retained in the file doc/pcre.txt, which is a concatenation in text format
921        of all the man pages except the little individual ones for each function.
923     7. The NON-UNIX-USE file had not been updated for the different set of source
924        files that come with release 6. I also added a few comments about the C++
925        wrapper.
928    Version 6.0 07-Jun-05
929    ---------------------
931     1. Some minor internal re-organization to help with my DFA experiments.
933     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
934        didn't matter for the library itself when fully configured, but did matter
935        when compiling without UCP support, or within Exim, where the ucp files are
936        not imported.
938     3. Refactoring of the library code to split up the various functions into
939        different source modules. The addition of the new DFA matching code (see
940        below) to a single monolithic source would have made it really too
941        unwieldy, quite apart from causing all the code to be include in a
942        statically linked application, when only some functions are used. This is
943        relevant even without the DFA addition now that patterns can be compiled in
944        one application and matched in another.
946        The downside of splitting up is that there have to be some external
947        functions and data tables that are used internally in different modules of
948        the library but which are not part of the API. These have all had their
949        names changed to start with "_pcre_" so that they are unlikely to clash
950        with other external names.
952     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
953        a different (DFA) algorithm. Although it is slower than the original
954        function, it does have some advantages for certain types of matching
955        problem.
957     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
958        including restarting after a partial match.
960     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
961        defined when compiling for Windows was sent to me. I have put it into the
962        code, though I have no means of testing or verifying it.
964     7. Added the pcre_refcount() auxiliary function.
966     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
967        match before or at the first newline in the subject string. In pcretest,
968        the /f option on a pattern can be used to set this.
970     9. A repeated \w when used in UTF-8 mode with characters greater than 256
971        would behave wrongly. This has been present in PCRE since release 4.0.
973    10. A number of changes to the pcregrep command:
975        (a) Refactored how -x works; insert ^(...)$ instead of setting
976            PCRE_ANCHORED and checking the length, in preparation for adding
977            something similar for -w.
979        (b) Added the -w (match as a word) option.
981        (c) Refactored the way lines are read and buffered so as to have more
982            than one at a time available.
984        (d) Implemented a pcregrep test script.
986        (e) Added the -M (multiline match) option. This allows patterns to match
987            over several lines of the subject. The buffering ensures that at least
988            8K, or the rest of the document (whichever is the shorter) is available
989            for matching (and similarly the previous 8K for lookbehind assertions).
991        (f) Changed the --help output so that it now says
993              -w, --word-regex(p)
995            instead of two lines, one with "regex" and the other with "regexp"
996            because that confused at least one person since the short forms are the
997            same. (This required a bit of code, as the output is generated
998            automatically from a table. It wasn't just a text change.)
1000        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1001            option but starts with a hyphen. Could be a pattern or a path name
1002            starting with a hyphen, for instance.
1004        (h) "-" can be given as a file name to represent stdin.
1006        (i) When file names are being printed, "(standard input)" is used for
1007            the standard input, for compatibility with GNU grep. Previously
1008            "<stdin>" was used.
1010        (j) The option --label=xxx can be used to supply a name to be used for
1011            stdin when file names are being printed. There is no short form.
1013        (k) Re-factored the options decoding logic because we are going to add
1014            two more options that take data. Such options can now be given in four
1015            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1017        (l) Added the -A, -B, and -C options for requesting that lines of context
1018            around matches be printed.
1020        (m) Added the -L option to print the names of files that do not contain
1021            any matching lines, that is, the complement of -l.
1023        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1024            continue to scan other files.
1026        (o) The -s option was incorrectly implemented. For compatibility with other
1027            greps, it now suppresses the error message for a non-existent or non-
1028            accessible file (but not the return code). There is a new option called
1029            -q that suppresses the output of matching lines, which was what -s was
1030            previously doing.
1032        (p) Added --include and --exclude options to specify files for inclusion
1033            and exclusion when recursing.
1035    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1036        Hopefully, it now does.
1038    12. Missing cast in pcre_study().
1040    13. Added an "uninstall" target to the makefile.
1042    14. Replaced "extern" in the function prototypes in Makefile.in with
1043        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1044        world, but is set differently for Windows.
1046    15. Added a second compiling function called pcre_compile2(). The only
1047        difference is that it has an extra argument, which is a pointer to an
1048        integer error code. When there is a compile-time failure, this is set
1049        non-zero, in addition to the error test pointer being set to point to an
1050        error message. The new argument may be NULL if no error number is required
1051        (but then you may as well call pcre_compile(), which is now just a
1052        wrapper). This facility is provided because some applications need a
1053        numeric error indication, but it has also enabled me to tidy up the way
1054        compile-time errors are handled in the POSIX wrapper.
1056    16. Added VPATH=.libs to the makefile; this should help when building with one
1057        prefix path and installing with another. (Or so I'm told by someone who
1058        knows more about this stuff than I do.)
1060    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1061        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1062        match everything, including newlines. This is not POSIX-compatible, but
1063        somebody wanted the feature. From pcretest it can be activated by using
1064        both the P and the s flags.
1066    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1068    19. libpcre.pc was being incorrectly installed as executable.
1070    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1071        it now also looks for '\r' so that it will work unmodified on Windows.
1073    21. Added Google's contributed C++ wrapper to the distribution.
1075    22. Added some untidy missing memory free() calls in pcretest, to keep
1076        Electric Fence happy when testing.
1080    Version 5.0 13-Sep-04
1081    ---------------------
1083     1. Internal change: literal characters are no longer packed up into items
1084        containing multiple characters in a single byte-string. Each character
1085        is now matched using a separate opcode. However, there may be more than one
1086        byte in the character in UTF-8 mode.
1088     2. The pcre_callout_block structure has two new fields: pattern_position and
1089        next_item_length. These contain the offset in the pattern to the next match
1090        item, and its length, respectively.
1092     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1093        insertion of callouts before each pattern item. Added the /C option to
1094        pcretest to make use of this.
1096     4. On the advice of a Windows user, the lines
1098          #if defined(_WIN32) || defined(WIN32)
1099          _setmode( _fileno( stdout ), 0x8000 );
1100          #endif  /* defined(_WIN32) || defined(WIN32) */
1102        have been added to the source of pcretest. This apparently does useful
1103        magic in relation to line terminators.
1105     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1106        for the benefit of those environments where the "b" makes a difference.
1108     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1109        to know about it. I have put a hack into configure.in that adds in code
1110        to set GCC=yes if CC=icc. This seems to end up at a point in the
1111        generated configure script that is early enough to affect the setting of
1112        compiler options, which is what is needed, but I have no means of testing
1113        whether it really works. (The user who reported this had patched the
1114        generated configure script, which of course I cannot do.)
1116        LATER: After change 22 below (new libtool files), the configure script
1117        seems to know about icc (and also ecc). Therefore, I have commented out
1118        this hack in configure.in.
1120     7. Added support for pkg-config (2 patches were sent in).
1122     8. Negated POSIX character classes that used a combination of internal tables
1123        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1124        [[:^ascii]]. Typically, they would match almost any characters. The other
1125        POSIX classes were not broken in this way.
1127     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1128        to find the match, as PCRE was deluded into thinking that the match had to
1129        start at the start point or following a newline. The same bug applied to
1130        patterns with negative forward assertions or any backward assertions
1131        preceding ".*" at the start, unless the pattern required a fixed first
1132        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1134    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1135        starting at the last subject character, bytes beyond the end of the subject
1136        string were read.
1138    11. Renamed the variable "class" as "classbits" to make life easier for C++
1139        users. (Previously there was a macro definition, but it apparently wasn't
1140        enough.)
1142    12. Added the new field "tables" to the extra data so that tables can be passed
1143        in at exec time, or the internal tables can be re-selected. This allows
1144        a compiled regex to be saved and re-used at a later time by a different
1145        program that might have everything at different addresses.
1147    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1148        -R library as well as a -L library.
1150    14. The debugging options of pcretest (-d on the command line or D on a
1151        pattern) showed incorrect output for anything following an extended class
1152        that contained multibyte characters and which was followed by a quantifier.
1154    15. Added optional support for general category Unicode character properties
1155        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1156        support. It adds about 90K to the size of the library. The meanings of the
1157        inbuilt class escapes such as \d and \s have NOT been changed.
1159    16. Updated pcredemo.c to include calls to free() to release the memory for the
1160        compiled pattern.
1162    17. The generated file chartables.c was being created in the source directory
1163        instead of in the building directory. This caused the build to fail if the
1164        source directory was different from the building directory, and was
1165        read-only.
1167    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1168        file. No doubt somebody will tell me if they don't make sense... Also added
1169        Dan Mooney's comments about building on OpenVMS.
1171    19. Added support for partial matching via the PCRE_PARTIAL option for
1172        pcre_exec() and the \P data escape in pcretest.
1174    20. Extended pcretest with 3 new pattern features:
1176        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1177              write the compiled pattern to the file whose name is "rest-of-line".
1178              This is a straight binary dump of the data, with the saved pointer to
1179              the character tables forced to be NULL. The study data, if any, is
1180              written too. After writing, pcretest reads a new pattern.
1182        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1183              compiled pattern from the given file. There must not be any
1184              occurrences of "<" in the file name (pretty unlikely); if there are,
1185              pcretest will instead treat the initial "<" as a pattern delimiter.
1186              After reading in the pattern, pcretest goes on to read data lines as
1187              usual.
1189        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1190              and 16-bit fields in a compiled pattern, to simulate a pattern that
1191              was compiled on a host of opposite endianness.
1193    21. The pcre-exec() function can now cope with patterns that were compiled on
1194        hosts of opposite endianness, with this restriction:
1196          As for any compiled expression that is saved and used later, the tables
1197          pointer field cannot be preserved; the extra_data field in the arguments
1198          to pcre_exec() should be used to pass in a tables address if a value
1199          other than the default internal tables were used at compile time.
1201    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1202        now diagnosed as an error. Previously, most of the time, a negative number
1203        would have been treated as zero, but if in addition "ovector" was passed as
1204        NULL, a crash could occur.
1206    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1207        new versions from the libtool 1.5 distribution (the last one is a copy of
1208        a file called libtool.m4). This seems to have fixed the need to patch
1209        "configure" to support Darwin 1.3 (which I used to do). However, I still
1210        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1211        workstation).
1213    24. Changed the PCRE licence to be the more standard "BSD" licence.
1216    Version 4.5 01-Dec-03
1217    ---------------------
1219     1. There has been some re-arrangement of the code for the match() function so
1220        that it can be compiled in a version that does not call itself recursively.
1221        Instead, it keeps those local variables that need separate instances for
1222        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1223        needs to "recurse". Keeping track of where control must go is done by means
1224        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1225        hide most of the details from the main code, and operates only if
1226        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1227        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1228        operating.
1230        To make it easier for callers to provide specially tailored get/free
1231        functions for this usage, two new functions, pcre_stack_malloc, and
1232        pcre_stack_free, are used. They are always called in strict stacking order,
1233        and the size of block requested is always the same.
1235        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1236        PCRE has been compiled to use the stack or the heap for recursion. The
1237        -C option of pcretest uses this to show which version is compiled.
1239        A new data escape \S, is added to pcretest; it causes the amounts of store
1240        obtained and freed by both kinds of malloc/free at match time to be added
1241        to the output.
1243     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1244        what's available on my current Linux desktop machine.
1246     3. When matching a UTF-8 string, the test for a valid string at the start has
1247        been extended. If start_offset is not zero, PCRE now checks that it points
1248        to a byte that is the start of a UTF-8 character. If not, it returns
1249        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1250        this is necessary because there may be backward assertions in the pattern.
1251        When matching the same subject several times, it may save resources to use
1252        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1254     4. The code for checking the validity of UTF-8 strings has been tightened so
1255        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1256        containing "overlong sequences".
1258     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1259        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1260        should have been "&", but it just so happened that all the cases this let
1261        through by mistake were picked up later in the function.
1263     6. I had used a variable called "isblank" - this is a C99 function, causing
1264        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1266     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1267        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1268        so the version is shown; (c) stop "make test" echoing "./RunTest".
1270     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1272     9. The prototype for memmove() for systems that don't have it was using
1273        size_t, but the inclusion of the header that defines size_t was later. I've
1274        moved the #includes for the C headers earlier to avoid this.
1276    10. Added some adjustments to the code to make it easier to compiler on certain
1277        special systems:
1279          (a) Some "const" qualifiers were missing.
1280          (b) Added the macro EXPORT before all exported functions; by default this
1281              is defined to be empty.
1282          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1283              that it reads its output file name as an argument instead of writing
1284              to the standard output and assuming this can be redirected.
1286    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1287        class containing characters with values greater than 255, PCRE compilation
1288        went into a loop.
1290    12. A recursive reference to a subpattern that was within another subpattern
1291        that had a minimum quantifier of zero caused PCRE to crash. For example,
1292        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1293        recursion. If the recursively-called subpattern itself had a zero repeat,
1294        that was OK.
1296    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1297        buffer into which it was copied (for escape processing) was still set at
1298        1024, so long lines caused crashes.
1300    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1301        "internal error: code overflow...". This applied to any character class
1302        that was followed by a possessive quantifier.
1304    15. Modified the Makefile to add libpcre.la as a prerequisite for
1305        libpcreposix.la because I was told this is needed for a parallel build to
1306        work.
1308    16. If a pattern that contained .* following optional items at the start was
1309        studied, the wrong optimizing data was generated, leading to matching
1310        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1311        matching string must start with a or b or c. The correct conclusion for
1312        this pattern is that a match can start with any character.
1315    Version 4.4 13-Aug-03
1316    ---------------------
1318     1. In UTF-8 mode, a character class containing characters with values between
1319        127 and 255 was not handled correctly if the compiled pattern was studied.
1320        In fixing this, I have also improved the studying algorithm for such
1321        classes (slightly).
1323     2. Three internal functions had redundant arguments passed to them. Removal
1324        might give a very teeny performance improvement.
1326     3. Documentation bug: the value of the capture_top field in a callout is *one
1327        more than* the number of the hightest numbered captured substring.
1329     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1330        in incorrectly linking with a previously installed version. They now link
1331        explicitly with libpcre.la.
1333     5. configure.in no longer needs to recognize Cygwin specially.
1335     6. A problem in pcre.in for Windows platforms is fixed.
1337     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1338        pcretest, it used to include the size of the study block as part of its
1339        output. Unfortunately, the structure contains a field that has a different
1340        size on different hardware architectures. This meant that the tests that
1341        showed this size failed. As the block is currently always of a fixed size,
1342        this information isn't actually particularly useful in pcretest output, so
1343        I have just removed it.
1345     8. Three pre-processor statements accidentally did not start in column 1.
1346        Sadly, there are *still* compilers around that complain, even though
1347        standard C has not required this for well over a decade. Sigh.
1349     9. In pcretest, the code for checking callouts passed small integers in the
1350        callout_data field, which is a void * field. However, some picky compilers
1351        complained about the casts involved for this on 64-bit systems. Now
1352        pcretest passes the address of the small integer instead, which should get
1353        rid of the warnings.
1355    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1356        both compile and run time, and gives an error if an invalid UTF-8 sequence
1357        is found. There is a option for disabling this check in cases where the
1358        string is known to be correct and/or the maximum performance is wanted.
1360    11. In response to a bug report, I changed one line in Makefile.in from
1362            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1363        to
1364            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1366        to look similar to other lines, but I have no way of telling whether this
1367        is the right thing to do, as I do not use Windows. No doubt I'll get told
1368        if it's wrong...
1371    Version 4.3 21-May-03
1372    ---------------------
1374    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1375       Makefile.
1377    2. Some refactoring to improve the quality of the code:
1379       (i)   The utf8_table... variables are now declared "const".
1381       (ii)  The code for \cx, which used the "case flipping" table to upper case
1382             lower case letters, now just substracts 32. This is ASCII-specific,
1383             but the whole concept of \cx is ASCII-specific, so it seems
1384             reasonable.
1386       (iii) PCRE was using its character types table to recognize decimal and
1387             hexadecimal digits in the pattern. This is silly, because it handles
1388             only 0-9, a-f, and A-F, but the character types table is locale-
1389             specific, which means strange things might happen. A private
1390             table is now used for this - though it costs 256 bytes, a table is
1391             much faster than multiple explicit tests. Of course, the standard
1392             character types table is still used for matching digits in subject
1393             strings against \d.
1395       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1396             ending in _t are). So I've renamed it as ESC_tee.
1398    3. The first argument for regexec() in the POSIX wrapper should have been
1399       defined as "const".
1401    4. Changed pcretest to use malloc() for its buffers so that they can be
1402       Electric Fenced for debugging.
1404    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1405       to read one or more bytes before the start of the subject string. Often this
1406       had no effect on PCRE's behaviour, but in some circumstances it could
1407       provoke a segmentation fault.
1409    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1410       to try to read one or more bytes before the start of the subject string.
1412    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1413       UTF-8 support could misbehave in various ways if the subject string
1414       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1415       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1416       back over UTF-8 characters.)
1419    Version 4.2 14-Apr-03
1420    ---------------------
1422    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1424    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1425         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1426         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1427         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1428         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1429           and BUILD_EXEEXT
1430         Note: automatic setting of the BUILD variables is not yet working
1431         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1432           compile-time but not at link-time
1433         [LINK]: use for linking executables only
1434         make different versions for Windows and non-Windows
1435         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1436           libraries
1437         [LINK_FOR_BUILD]: new variable
1438         [OBJEXT]: use throughout
1439         [EXEEXT]: use throughout
1440         <winshared>: new target
1441         <wininstall>: new target
1442         <dftables.o>: use native compiler
1443         <dftables>: use native linker
1444         <install>: handle Windows platform correctly
1445         <clean>: ditto
1446         <check>: ditto
1447         copy DLL to top builddir before testing
1449       As part of these changes, -no-undefined was removed again. This was reported
1450       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1451       in any case.
1453    3. Some tidies to get rid of compiler warnings:
1455       . In the match_data structure, match_limit was an unsigned long int, whereas
1456         match_call_count was an int. I've made them both unsigned long ints.
1458       . In pcretest the fact that a const uschar * doesn't automatically cast to
1459         a void * provoked a warning.
1461       . Turning on some more compiler warnings threw up some "shadow" variables
1462         and a few more missing casts.
1464    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1465       option, a class that contained a single character with a value between 128
1466       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1468    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1469       option, a class that contained several characters, but with at least one
1470       whose value was between 128 and 255 caused PCRE to crash.
1473    Version 4.1 12-Mar-03
1474    ---------------------
1476    1. Compiling with gcc -pedantic found a couple of places where casts were
1477    needed, and a string in dftables.c that was longer than standard compilers are
1478    required to support.
1480    2. Compiling with Sun's compiler found a few more places where the code could
1481    be tidied up in order to avoid warnings.
1483    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1484    first of these names is deprecated in the latest Autoconf in favour of the name
1485    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1486    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1487    analogy I have changed it to CFLAGS_FOR_BUILD.
1489    4. Added -no-undefined to the linking command in the Makefile, because this is
1490    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1491    linking step for the pcreposix library.
1493    5. PCRE was failing to diagnose the case of two named groups with the same
1494    name.
1496    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1497    literal character that is needed in the subject for a match, and scans along to
1498    ensure that it is present before embarking on the full matching process. This
1499    saves time in cases of nested unlimited repeats that are never going to match.
1500    Problem: the scan can take a lot of time if the subject is very long (e.g.
1501    megabytes), thus penalizing straightforward matches. It is now done only if the
1502    amount of subject to be scanned is less than 1000 bytes.
1504    7. A lesser problem with the same optimization is that it was recording the
1505    first character of an anchored pattern as "needed", thus provoking a search
1506    right along the subject, even when the first match of the pattern was going to
1507    fail. The "needed" character is now not set for anchored patterns, unless it
1508    follows something in the pattern that is of non-fixed length. Thus, it still
1509    fulfils its original purpose of finding quick non-matches in cases of nested
1510    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1513    Version 4.0 17-Feb-03
1514    ---------------------
1516    1. If a comment in an extended regex that started immediately after a meta-item
1517    extended to the end of string, PCRE compiled incorrect data. This could lead to
1518    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1520    2. Moved to autoconf 2.53 and libtool 1.4.2.
1522    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1523    the special perltest8 script is no longer needed - all the tests can be run
1524    from a single perltest script.
1526    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1527    by \s. It has now been removed in PCRE. This means it isn't recognized as
1528    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1529    class [:space:] *does* include VT, thereby creating a mess.
1531    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1532    space and tab.
1534    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1535    its new features into the main test script, reducing the number of scripts.
1537    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1538    were backward compatible, and made the (?i) apply to the whole pattern, as if
1539    /i were given. Now it behaves more logically, and applies the option setting
1540    only to what follows. PCRE has been changed to follow suit. However, if it
1541    finds options settings right at the start of the pattern, it extracts them into
1542    the global options, as before. Thus, they show up in the info data.
1544    8. Added support for the \Q...\E escape sequence. Characters in between are
1545    treated as literals. This is slightly different from Perl in that $ and @ are
1546    also handled as literals inside the quotes. In Perl, they will cause variable
1547    interpolation. Note the following examples:
1549        Pattern            PCRE matches      Perl matches
1551        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1552        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1553        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1555    For compatibility with Perl, \Q...\E sequences are recognized inside character
1556    classes as well as outside them.
1558    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1559    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1560    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1561    signed/unsigned warnings.
1563    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1564    option for pcretest, so I've replaced it by a simple function that does just
1565    that job.
1567    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1568    "pcregrep -".
1570    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1571    Java package. This provides some syntactic sugar for simple cases of what my
1572    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1573    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1574    item, you can use this simplified notation. Note that only makes sense with
1575    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1576    greediness, whatever the setting of the PCRE_UNGREEDY option.
1578    13. A change of greediness default within a pattern was not taking effect at
1579    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1580    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1581    was abstracted outside.
1583    14. PCRE now supports the \G assertion. It is true when the current matching
1584    position is at the start point of the match. This differs from \A when the
1585    starting offset is non-zero. Used with the /g option of pcretest (or similar
1586    code), it works in the same way as it does for Perl's /g option. If all
1587    alternatives of a regex begin with \G, the expression is anchored to the start
1588    match position, and the "anchored" flag is set in the compiled expression.
1590    15. Some bugs concerning the handling of certain option changes within patterns
1591    have been fixed. These applied to options other than (?ims). For example,
1592    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1593    been the other way round. Some of this was related to change 7 above.
1595    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1596    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1597    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1598    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1600    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1601    mode. Unlike ".", it always matches newline, whatever the setting of
1602    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1603    assertions. Perl allows it, but it doesn't (in general) work because it can't
1604    calculate the length of the lookbehind. At least, that's the case for Perl
1605    5.8.0 - I've been told they are going to document that it doesn't work in
1606    future.
1608    18. Added an error diagnosis for escapes that PCRE does not support: these are
1609    \L, \l, \N, \P, \p, \U, \u, and \X.
1611    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1612    reading past the end of the pattern in cases such as /[abcd/.
1614    20. PCRE was getting more memory than necessary for patterns with classes that
1615    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1617    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1618    compiling PCRE for use with Virtual Pascal.
1620    22. Small fix to the Makefile to make it work properly if the build is done
1621    outside the source tree.
1623    23. Added a new extension: a condition to go with recursion. If a conditional
1624    subpattern starts with (?(R) the "true" branch is used if recursion has
1625    happened, whereas the "false" branch is used only at the top level.
1627    24. When there was a very long string of literal characters (over 255 bytes
1628    without UTF support, over 250 bytes with UTF support), the computation of how
1629    much memory was required could be incorrect, leading to segfaults or other
1630    strange effects.
1632    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1633    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1634    there was a subsequent back reference to those brackets. This meant that, for
1635    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1636    possible to check for precisely this case. All we can do is abandon the
1637    optimization if .* occurs inside capturing brackets when there are any back
1638    references whatsoever. (See below for a better fix that came later.)
1640    26. The handling of the optimization for finding the first character of a
1641    non-anchored pattern, and for finding a character that is required later in the
1642    match were failing in some cases. This didn't break the matching; it just
1643    failed to optimize when it could. The way this is done has been re-implemented.
1645    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1647    28. Added a new feature that provides some of the functionality that Perl
1648    provides with (?{...}). The facility is termed a "callout". The way it is done
1649    in PCRE is for the caller to provide an optional function, by setting
1650    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1651    global variable. By default it is unset, which disables all calling out. To get
1652    the function called, the regex must include (?C) at appropriate points. This
1653    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1654    This provides a means of identifying different callout points. When PCRE
1655    reaches such a point in the regex, if pcre_callout has been set, the external
1656    function is called. It is provided with data in a structure called
1657    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1658    matching continues; if it returns a non-zero value, the match at the current
1659    point fails. However, backtracking will occur if possible. [This was changed
1660    later and other features added - see item 49 below.]
1662    29. pcretest is upgraded to test the callout functionality. It provides a
1663    callout function that displays information. By default, it shows the start of
1664    the match and the current position in the text. There are some new data escapes
1665    to vary what happens:
1667        \C+         in addition, show current contents of captured substrings
1668        \C-         do not supply a callout function
1669        \C!n        return 1 when callout number n is reached
1670        \C!n!m      return 1 when callout number n is reached for the mth time
1672    30. If pcregrep was called with the -l option and just a single file name, it
1673    output "<stdin>" if a match was found, instead of the file name.
1675    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1676    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1677    pcre_exec(). This saves a malloc/free per call. The default value of
1678    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1679    when configuring.
1681    32. The default maximum size of a compiled pattern is 64K. There have been a
1682    few cases of people hitting this limit. The code now uses macros to handle the
1683    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1684    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1685    configuring. Tests 2 and 5 work only with 2-byte links because they output
1686    debugging information about compiled patterns.
1688    33. Internal code re-arrangements:
1690    (a) Moved the debugging function for printing out a compiled regex into
1691        its own source file (printint.c) and used #include to pull it into
1692        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1693        separate copies.
1695    (b) Defined the list of op-code names for debugging as a macro in
1696        internal.h so that it is next to the definition of the opcodes.
1698    (c) Defined a table of op-code lengths for simpler skipping along compiled
1699        code. This is again a macro in internal.h so that it is next to the
1700        definition of the opcodes.
1702    34. Added support for recursive calls to individual subpatterns, along the
1703    lines of Robin Houston's patch (but implemented somewhat differently).
1705    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1706    allow it to read and process whole directories in Win32. This code was
1707    contributed by Lionel Fourquaux; it has not been tested by me.
1709    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1710    used to name a group. Names consist of alphanumerics and underscores, and must
1711    be unique. Back references use the syntax (?P=name) and recursive calls use
1712    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1713    numbers. The function pcre_fullinfo() can be used after compilation to extract
1714    a name/number map. There are three relevant calls:
1716      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1717      PCRE_INFO_NAMECOUNT            yields the number of entries
1718      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1720    The map is a vector of fixed-size entries. The size of each entry depends on
1721    the length of the longest name used. The first two bytes of each entry are the
1722    group number, most significant byte first. There follows the corresponding
1723    name, zero terminated. The names are in alphabetical order.
1725    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1726    case instead of 255. Making it the same both with and without UTF-8 support
1727    means that the same test output works with both.
1729    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1730    calling malloc() with a zero argument.
1732    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1733    optimization. I've improved things by keeping a bitmap of backreferences with
1734    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1735    fact referenced, the optimization can be applied. It is unlikely that a
1736    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1737    the match to follow \n) will appear inside brackets with a number greater than
1738    31, but if it does, any back reference > 31 suppresses the optimization.
1740    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1741    of disabling numbered capturing parentheses. Any opening parenthesis that is
1742    not followed by ? behaves as if it were followed by ?: but named parentheses
1743    can still be used for capturing (and they will acquire numbers in the usual
1744    way).
1746    41. Redesigned the return codes from the match() function into yes/no/error so
1747    that errors can be passed back from deep inside the nested calls. A malloc
1748    failure while inside a recursive subpattern call now causes the
1749    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1751    42. It is now possible to set a limit on the number of times the match()
1752    function is called in a call to pcre_exec(). This facility makes it possible to
1753    limit the amount of recursion and backtracking, though not in a directly
1754    obvious way, because the match() function is used in a number of different
1755    circumstances. The count starts from zero for each position in the subject
1756    string (for non-anchored patterns). The default limit is, for compatibility, a
1757    large number, namely 10 000 000. You can change this in two ways:
1759    (a) When configuring PCRE before making, you can use --with-match-limit=n
1760        to set a default value for the compiled library.
1762    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1763        a different value is set. See 45 below.
1765    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1767    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1768    of things that can be changed at compile time. The first argument specifies
1769    what is wanted and the second points to where the information is to be placed.
1770    The current list of available information is:
1772      PCRE_CONFIG_UTF8
1774    The output is an integer that is set to one if UTF-8 support is available;
1775    otherwise it is set to zero.
1779    The output is an integer that it set to the value of the code that is used for
1780    newline. It is either LF (10) or CR (13).
1784    The output is an integer that contains the number of bytes used for internal
1785    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1789    The output is an integer that contains the threshold above which the POSIX
1790    interface uses malloc() for output vectors. See item 31 above.
1794    The output is an unsigned integer that contains the default limit of the number
1795    of match() calls in a pcre_exec() execution. See 42 above.
1797    44. pcretest has been upgraded by the addition of the -C option. This causes it
1798    to extract all the available output from the new pcre_config() function, and to
1799    output it. The program then exits immediately.
1801    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1802    order to support additional features. One way would have been to define
1803    pcre_exec2() (for example) with extra arguments, but this would not have been
1804    extensible, and would also have required all calls to the original function to
1805    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1806    is used for passing in "extra" data from pcre_study().
1808    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1809    contains the following fields:
1811      flags         a bitmap indicating which of the following fields are set
1812      study_data    opaque data from pcre_study()
1813      match_limit   a way of specifying a limit on match() calls for a specific
1814                      call to pcre_exec()
1815      callout_data  data for callouts (see 49 below)
1817    The flag bits are also defined in pcre.h, and are
1823    The pcre_study() function now returns one of these new pcre_extra blocks, with
1824    the actual study data pointed to by the study_data field, and the
1825    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1826    before. That is, this change is entirely upwards-compatible and requires no
1827    change to existing code.
1829    If you want to pass in additional data to pcre_exec(), you can either place it
1830    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1831    block.
1833    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1834    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1835    times with different match limits, until it finds the minimum value needed for
1836    pcre_exec() to complete. The value is then output. This can be instructive; for
1837    most simple matches the number is quite small, but for pathological cases it
1838    gets very large very quickly.
1840    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1841    returns the size of the data block pointed to by the study_data field in a
1842    pcre_extra block, that is, the value that was passed as the argument to
1843    pcre_malloc() when PCRE was getting memory in which to place the information
1844    created by pcre_study(). The fourth argument should point to a size_t variable.
1845    pcretest has been extended so that this information is shown after a successful
1846    pcre_study() call when information about the compiled regex is being displayed.
1848    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1849    because what follows is always an absolute path. (Later: it turns out that this
1850    is more than cosmetic for MinGW, because it doesn't like empty path
1851    components.)
1853    49. Some changes have been made to the callout feature (see 28 above):
1855    (i)  A callout function now has three choices for what it returns:
1857           0  =>  success, carry on matching
1858         > 0  =>  failure at this point, but backtrack if possible
1859         < 0  =>  serious error, return this value from pcre_exec()
1861         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1862         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1863         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1864         use by callout functions. It will never be used by PCRE itself.
1866    (ii) The pcre_extra structure (see 45 above) has a void * field called
1867         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1868         pcre_callout_block structure has a field of the same name. The contents of
1869         the field passed in the pcre_extra structure are passed to the callout
1870         function in the corresponding field in the callout block. This makes it
1871         easier to use the same callout-containing regex from multiple threads. For
1872         testing, the pcretest program has a new data escape
1874           \C*n        pass the number n (may be negative) as callout_data
1876         If the callout function in pcretest receives a non-zero value as
1877         callout_data, it returns that value.
1879    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1880    there were some redundant $(CFLAGS) in commands that are now specified as
1881    $(LINK), which already includes $(CFLAGS).
1883    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1884    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1885    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1886    one-byte characters throughout. Note that case-insensitive matching applies
1887    only to characters whose values are less than 256. PCRE doesn't support the
1888    notion of cases for higher-valued characters.
1890    (i)   A character class whose characters are all within 0-255 is handled as
1891          a bit map, and the map is inverted for negative classes. Previously, a
1892          character > 255 always failed to match such a class; however it should
1893          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1895    (ii)  A negated character class with a single character < 255 is coded as
1896          "not this character" (OP_NOT). This wasn't working properly when the test
1897          character was multibyte, either singly or repeated.
1899    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1900          mode, for example: \x{100}{2,3}.
1902    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1903          singly or repeated) now correctly test multibyte characters. However,
1904          PCRE doesn't recognize any characters with values greater than 255 as
1905          digits, spaces, or word characters. Such characters always match \D, \S,
1906          and \W, and never match \d, \s, or \w.
1908    (v)   Classes may now contain characters and character ranges with values
1909          greater than 255. For example: [ab\x{100}-\x{400}].
1911    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1912          PCRE in UTF-8 mode.
1914    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1915    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1916    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1917    value.)
1919    53. The single man page has become too large. I have therefore split it up into
1920    a number of separate man pages. These also give rise to individual HTML pages;
1921    these are now put in a separate directory, and there is an index.html page that
1922    lists them all. Some hyperlinking between the pages has been installed.
1924    54. Added convenience functions for handling named capturing parentheses.
1926    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1927    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1928    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1929    are faulted.
1931    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1932    calling configure. These values are used when compiling the dftables.c program
1933    which is run to generate the source of the default character tables. They
1934    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1935    you will need to set these values.
1937    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1940    Version 3.9 02-Jan-02
1941    ---------------------
1943    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1945    2. If --disable-static was given, the building process failed when trying to
1946    build pcretest and pcregrep. (For some reason it was using libtool to compile
1947    them, which is not right, as they aren't part of the library.)
1950    Version 3.8 18-Dec-01
1951    ---------------------
1953    1. The experimental UTF-8 code was completely screwed up. It was packing the
1954    bytes in the wrong order. How dumb can you get?
1957    Version 3.7 29-Oct-01
1958    ---------------------
1960    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1961    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1962    this didn't happen under Solaris 8, where I normally test things.
1964    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1965    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1966    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1967    this fix an hour or so after the initial 3.7 release.)
1970    Version 3.6 23-Oct-01
1971    ---------------------
1973    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1974    offsets passed as NULL with zero offset count.
1976    2. The config.guess and config.sub files had not been updated when I moved to
1977    the latest autoconf.
1980    Version 3.5 15-Aug-01
1981    ---------------------
1983    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1984    had been forgotten.
1986    2. By using declared but undefined structures, we can avoid using "void"
1987    definitions in pcre.h while keeping the internal definitions of the structures
1988    private.
1990    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1991    user point of view, this means that both static and shared libraries are built
1992    by default, but this can be individually controlled. More of the work of
1993    handling this static/shared cases is now inside libtool instead of PCRE's make
1994    file.
1996    4. The pcretest utility is now installed along with pcregrep because it is
1997    useful for users (to test regexs) and by doing this, it automatically gets
1998    relinked by libtool. The documentation has been turned into a man page, so
1999    there are now .1, .txt, and .html versions in /doc.
2001    5. Upgrades to pcregrep:
2002       (i)   Added long-form option names like gnu grep.
2003       (ii)  Added --help to list all options with an explanatory phrase.
2004       (iii) Added -r, --recursive to recurse into sub-directories.
2005       (iv)  Added -f, --file to read patterns from a file.
2007    6. pcre_exec() was referring to its "code" argument before testing that
2008    argument for NULL (and giving an error if it was NULL).
2010    7. Upgraded Makefile.in to allow for compiling in a different directory from
2011    the source directory.
2013    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2014    options bits, the pointer it was passed was to an int instead of to an unsigned
2015    long int. This mattered only on 64-bit systems.
2017    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2018    generated) instead of pcre.in, which it its source. Also made the same change
2019    in several of the .c files.
2021    10. A new release of gcc defines printf() as a macro, which broke pcretest
2022    because it had an ifdef in the middle of a string argument for printf(). Fixed
2023    by using separate calls to printf().
2025    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2026    script, to force use of CR or LF instead of \n in the source. On non-Unix
2027    systems, the value can be set in config.h.
2029    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2030    absolute limit. Changed the text of the error message to make this clear, and
2031    likewise updated the man page.
2033    13. The limit of 99 on the number of capturing subpatterns has been removed.
2034    The new limit is 65535, which I hope will not be a "real" limit.
2037    Version 3.4 22-Aug-00
2038    ---------------------
2040    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2042    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2045    Version 3.3 01-Aug-00
2046    ---------------------
2048    1. If an octal character was given, but the value was greater than \377, it
2049    was not getting masked to the least significant bits, as documented. This could
2050    lead to crashes in some systems.
2052    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2053    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2055    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2056    These just pass their arguments on to (pcre_free)(), but they are provided
2057    because some uses of PCRE bind it to non-C systems that can call its functions,
2058    but cannot call free() or pcre_free() directly.
2060    4. Add "make test" as a synonym for "make check". Corrected some comments in
2061    the Makefile.
2063    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2064    Makefile.
2066    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2067    command called pgrep for grepping around the active processes.
2069    7. Added the beginnings of support for UTF-8 character strings.
2071    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2072    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2073    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2074    out for the ar command.)
2077    Version 3.2 12-May-00
2078    ---------------------
2080    This is purely a bug fixing release.
2082    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2083    of ZA. This was just one example of several cases that could provoke this bug,
2084    which was introduced by change 9 of version 2.00. The code for breaking
2085    infinite loops after an iteration that matches an empty string was't working
2086    correctly.
2088    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2089    when matched against abbab (for example). After matching an empty string, it
2090    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2091    caused it to match further down the string than it should.
2093    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2094    was there because it doesn't seem to be needed, and it causes trouble on some
2095    systems, as it is not a Standard C header. It has been removed.
2097    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2098    were reported on the Macintosh. The changes were from
2100      while ((c = *(++ptr)) != 0 && c != '\n');
2101    to
2102      while ((c = *(++ptr)) != 0 && c != '\n') ;
2104    Totally extraordinary, but if that's what it takes...
2106    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2107    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2108    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2109    assumes the way PCRE uses memmove() (always moving upwards).
2111    6. PCRE is being used in one environment where strchr() is not available. There
2112    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2113    faster code anyway.
2116    Version 3.1 09-Feb-00
2117    ---------------------
2119    The only change in this release is the fixing of some bugs in Makefile.in for
2120    the "install" target:
2122    (1) It was failing to install pcreposix.h.
2124    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2127    Version 3.0 01-Feb-00
2128    ---------------------
2130    1. Add support for the /+ modifier to perltest (to output $` like it does in
2131    pcretest).
2133    2. Add support for the /g modifier to perltest.
2135    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2136    matches null strings.
2138    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2139    pattern. Perl treats empty patterns specially - it reuses the most recent
2140    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2141    effect.
2143    5. The POSIX interface was broken in that it was just handing over the POSIX
2144    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2145    required a bigger vector, with some working space on the end. This means that
2146    the POSIX wrapper now has to get and free some memory, and copy the results.
2148    6. Added some simple autoconf support, placing the test data and the
2149    documentation in separate directories, re-organizing some of the
2150    information files, and making it build pcre-config (a GNU standard). Also added
2151    libtool support for building PCRE as a shared library, which is now the
2152    default.
2154    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2155    09 are not valid octal constants. Single digits will be used for minor values
2156    less than 10.
2158    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2159    existing programs that set these in the POSIX interface can use PCRE without
2160    modification.
2162    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2163    return all that pcre_info() returns, plus additional data. The pcre_info()
2164    function is retained for compatibility, but is considered to be obsolete.
2166    10. Added experimental recursion feature (?R) to handle one common case that
2167    Perl 5.6 will be able to do with (?p{...}).
2169    11. Added support for POSIX character classes like [:alpha:], which Perl is
2170    adopting.
2173    Version 2.08 31-Aug-99
2174    ----------------------
2176    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2177    trying to match at the startoffset position, but instead was moving forward to
2178    the next newline as if a previous match had failed.
2180    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2181    and could get into a loop if a null string was matched other than at the start
2182    of the subject.
2184    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2185    be distinguished at compile time, and for completeness also added PCRE_DATE.
2187    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2188    in GnuWin32 environments.
2191    Version 2.07 29-Jul-99
2192    ----------------------
2194    1. The documentation is now supplied in plain text form and HTML as well as in
2195    the form of man page sources.
2197    2. C++ compilers don't like assigning (void *) values to other pointer types.
2198    In particular this affects malloc(). Although there is no problem in Standard
2199    C, I've put in casts to keep C++ compilers happy.
2201    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2202    should be (const char *).
2204    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2205    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2206    However, I haven't made this a standard facility. The documentation doesn't
2207    mention it, and the Makefile doesn't support it.
2209    5. The Makefile now contains an "install" target, with editable destinations at
2210    the top of the file. The pcretest program is not installed.
2212    6. pgrep -V now gives the PCRE version number and date.
2214    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2215    causing the entire string to be ignored, instead of just the last character.
2217    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2218    non-matching string, it can take a very, very long time, even for strings of
2219    quite modest length, because of the nested recursion. PCRE now does better in
2220    some of these cases. It does this by remembering the last required literal
2221    character in the pattern, and pre-searching the subject to ensure it is present
2222    before running the real match. In other words, it applies a heuristic to detect
2223    some types of certain failure quickly, and in the above example, if presented
2224    with a string that has no trailing " it gives "no match" very quickly.
2226    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2227    other alternatives are tried instead.
2230    Version 2.06 09-Jun-99
2231    ----------------------
2233    1. Change pcretest's output for amount of store used to show just the code
2234    space, because the remainder (the data block) varies in size between 32-bit and
2235    64-bit systems.
2237    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2238    start matching at. This allows lookbehinds to work when searching for multiple
2239    occurrences in a string.
2241    3. Added additional options to pcretest for testing multiple occurrences:
2243       /+   outputs the rest of the string that follows a match
2244       /g   loops for multiple occurrences, using the new startoffset argument
2245       /G   loops for multiple occurrences by passing an incremented pointer
2247    4. PCRE wasn't doing the "first character" optimization for patterns starting
2248    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2249    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2250    the letter 'x'. On long subject strings, this gives a significant speed-up.
2253    Version 2.05 21-Apr-99
2254    ----------------------
2256    1. Changed the type of magic_number from int to long int so that it works
2257    properly on 16-bit systems.
2259    2. Fixed a bug which caused patterns starting with .* not to work correctly
2260    when the subject string contained newline characters. PCRE was assuming
2261    anchoring for such patterns in all cases, which is not correct because .* will
2262    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2263    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2264    must be retried after every newline in the subject.
2267    Version 2.04 18-Feb-99
2268    ----------------------
2270    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2271    computation of the store needed to hold the pattern was incorrect (too large).
2272    If such patterns were nested a few deep, this could multiply and become a real
2273    problem.
2275    2. Added /M option to pcretest to show the memory requirement of a specific
2276    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2278    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2279    compiled in such a way that the backtracking after subsequent failure was
2280    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2281    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2284    Version 2.03 02-Feb-99
2285    ----------------------
2287    1. Fixed typo and small mistake in man page.
2289    2. Added 4th condition (GPL supersedes if conflict) and created separate
2290    LICENCE file containing the conditions.
2292    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2293    Perl, that is the internal \ allows the delimiter to be included in the
2294    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2295    the final delimiter, add \ to the end of the pattern (to test the error).
2297    4. Added the convenience functions for extracting substrings after a successful
2298    match. Updated pcretest to make it able to test these functions.
2301    Version 2.02 14-Jan-99
2302    ----------------------
2304    1. Initialized the working variables associated with each extraction so that
2305    their saving and restoring doesn't refer to uninitialized store.
2307    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2308    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2309    fix the problem.
2311    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2312    calls, and wasn't printing the correct value for compiling calls. Increased the
2313    default value of LOOPREPEAT, and the number of significant figures in the
2314    times.
2316    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2318    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2319    a building problem on Windows NT with a FAT file system.
2322    Version 2.01 21-Oct-98
2323    ----------------------
2325    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2326    to character tables built by pcre_maketables() in the current locale. If NULL
2327    is passed, the default tables are used.
2330    Version 2.00 24-Sep-98
2331    ----------------------
2333    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2334    it any more.
2336    2. Allow quantification of (?>) groups, and make it work correctly.
2338    3. The first character computation wasn't working for (?>) groups.
2340    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2341    end of the subject) and add 5.005's \z, which really does match only at the
2342    very end of the subject.
2344    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2346    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2347    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2348    localized options. All options to pcre_study() were also removed.
2350    7. Add other new features from 5.005:
2352       $(?<=           positive lookbehind
2353       $(?<!           negative lookbehind
2354       (?imsx-imsx)    added the unsetting capability
2355                       such a setting is global if at outer level; local otherwise
2356       (?imsx-imsx:)   non-capturing groups with option setting
2357       (?(cond)re|re)  conditional pattern matching
2359       A backreference to itself in a repeated group matches the previous
2360       captured string.
2362    8. General tidying up of studying (both automatic and via "study")
2363    consequential on the addition of new assertions.
2365    9. As in 5.005, unlimited repeated groups that could match an empty substring
2366    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2367    runtime if any iteration does actually match an empty substring.
2369    10. Include the RunTest script in the distribution.
2371    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2372    discrepancies, some of which were old and were also with respect to 5.004. They
2373    have now been fixed.
2376    Version 1.09 28-Apr-98
2377    ----------------------
2379    1. A negated single character class followed by a quantifier with a minimum
2380    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2381    program crashes, or just wrong answers. This did not apply to negated classes
2382    containing more than one character, or to minima other than one.
2385    Version 1.08 27-Mar-98
2386    ----------------------
2388    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2390    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2391    latter must appear before anything that relies on it in the pattern.
2394    Version 1.07 16-Feb-98
2395    ----------------------
2397    1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2398    repeat of a potentially empty string).
2401  Version 1.06 23-Jan-98  Version 1.06 23-Jan-98
2402  ----------------------  ----------------------

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