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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 01-May-07
5    ---------------------
7     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
8        which is apparently normally available under Windows.
11    Version 7.1 24-Apr-07
12    ---------------------
14     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
15        that is more "standard", making use of automake and other Autotools. There
16        is some re-arrangement of the files and adjustment of comments consequent
17        on this.
19     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
20        for recursive directory scanning broke on some systems because the files
21        are not scanned in any specific order and on different systems the order
22        was different. A call to "sort" has been inserted into RunGrepTest for the
23        approprate test as a short-term fix. In the longer term there may be an
24        alternative.
26     3. I had an email from Eric Raymond about problems translating some of PCRE's
27        man pages to HTML (despite the fact that I distribute HTML pages, some
28        people do their own conversions for various reasons). The problems
29        concerned the use of low-level troff macros .br and .in. I have therefore
30        removed all such uses from the man pages (some were redundant, some could
31        be replaced by .nf/.fi pairs). The 132html script that I use to generate
32        HTML has been updated to handle .nf/.fi and to complain if it encounters
33        .br or .in.
35     4. Updated comments in configure.ac that get placed in config.h.in and also
36        arranged for config.h to be included in the distribution, with the name
37        config.h.generic, for the benefit of those who have to compile without
38        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
40     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
41        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
42        makevp.bat for the current PCRE, using the additional files
43        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
45     6. A Windows user reported a minor discrepancy with test 2, which turned out
46        to be caused by a trailing space on an input line that had got lost in his
47        copy. The trailing space was an accident, so I've just removed it.
49     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
50        that is needed.
52     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
53        as "const" (a) because they are and (b) because it helps the PHP
54        maintainers who have recently made a script to detect big data structures
55        in the php code that should be moved to the .rodata section. I remembered
56        to update Builducptable as well, so it won't revert if ucptable.h is ever
57        re-created.
59     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
60        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
61        order to be able to cut out the UTF-8 tables in the latter when UTF-8
62        support is not required. This saves 1.5-2K of code, which is important in
63        some applications.
65        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
66        so as not to refer to the tables, even though these functions will never be
67        called when UTF-8 support is disabled. Otherwise there are problems with a
68        shared library.
70    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
72        (a) It was defining its arguments as char * instead of void *.
74        (b) It was assuming that all moves were upwards in memory; this was true
75            a long time ago when I wrote it, but is no longer the case.
77        The emulated memove() is provided for those environments that have neither
78        memmove() nor bcopy(). I didn't think anyone used it these days, but that
79        is clearly not the case, as these two bugs were recently reported.
81    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
82        and Detrail to create the HTML documentation, the .txt form of the man
83        pages, and it removes trailing spaces from listed files. It also creates
84        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
85        case, it wraps all the #defines with #ifndefs. This script should be run
86        before "make dist".
88    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
89        with Unicode property support.
91        (a) For a maximizing quantifier, if the two different cases of the
92            character were of different lengths in their UTF-8 codings (there are
93            some cases like this - I found 11), and the matching function had to
94            back up over a mixture of the two cases, it incorrectly assumed they
95            were both the same length.
97        (b) When PCRE was configured to use the heap rather than the stack for
98            recursion during matching, it was not correctly preserving the data for
99            the other case of a UTF-8 character when checking ahead for a match
100            while processing a minimizing repeat. If the check also involved
101            matching a wide character, but failed, corruption could cause an
102            erroneous result when trying to check for a repeat of the original
103            character.
105    13. Some tidying changes to the testing mechanism:
107        (a) The RunTest script now detects the internal link size and whether there
108            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
109            values substituted by "configure". (The RunGrepTest script already did
110            this for UTF-8.) The configure.ac script no longer substitutes the
111            relevant variables.
113        (b) The debugging options /B and /D in pcretest show the compiled bytecode
114            with length and offset values. This means that the output is different
115            for different internal link sizes. Test 2 is skipped for link sizes
116            other than 2 because of this, bypassing the problem. Unfortunately,
117            there was also a test in test 3 (the locale tests) that used /B and
118            failed for link sizes other than 2. Rather than cut the whole test out,
119            I have added a new /Z option to pcretest that replaces the length and
120            offset values with spaces. This is now used to make test 3 independent
121            of link size. (Test 2 will be tidied up later.)
123    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
124        segmentation fault instead of returning the appropriate error message.
126    15. In multiline mode when the newline sequence was set to "any", the pattern
127        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
128        This doesn't seem right; it now treats the CRLF combination as the line
129        ending, and so does not match in that case. It's only a pattern such as ^$
130        that would hit this one: something like ^ABC$ would have failed after \r
131        and then tried again after \r\n.
133    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
134        in an attempt to make files that differ only in their line terminators
135        compare equal. This works on Linux.
137    17. Under certain error circumstances pcregrep might try to free random memory
138        as it exited. This is now fixed, thanks to valgrind.
140    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
141        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
142        was because its rules for how to advance for /g after matching an empty
143        string at the end of a line did not allow for this case. They now check for
144        it specially.
146    20. pcretest is supposed to handle patterns and data of any length, by
147        extending its buffers when necessary. It was getting this wrong when the
148        buffer for a data line had to be extended.
150    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
151        CRLF as a newline sequence.
153    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
154        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
155        I have nevertheless tidied it up.
157    23. Added some casts to kill warnings from HP-UX ia64 compiler.
159    24. Added a man page for pcre-config.
162    Version 7.0 19-Dec-06
163    ---------------------
165     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
166        moving to gcc 4.1.1.
168     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
169        sys/time.h, which is documented as needed for this function. It doesn't
170        seem to matter on Linux, but it showed up on some releases of OS X.
172     3. It seems that there are systems where bytes whose values are greater than
173        127 match isprint() in the "C" locale. The "C" locale should be the
174        default when a C program starts up. In most systems, only ASCII printing
175        characters match isprint(). This difference caused the output from pcretest
176        to vary, making some of the tests fail. I have changed pcretest so that:
178        (a) When it is outputting text in the compiled version of a pattern, bytes
179            other than 32-126 are always shown as hex escapes.
181        (b) When it is outputting text that is a matched part of a subject string,
182            it does the same, unless a different locale has been set for the match
183            (using the /L modifier). In this case, it uses isprint() to decide.
185     4. Fixed a major bug that caused incorrect computation of the amount of memory
186        required for a compiled pattern when options that changed within the
187        pattern affected the logic of the preliminary scan that determines the
188        length. The relevant options are -x, and -i in UTF-8 mode. The result was
189        that the computed length was too small. The symptoms of this bug were
190        either the PCRE error "internal error: code overflow" from pcre_compile(),
191        or a glibc crash with a message such as "pcretest: free(): invalid next
192        size (fast)". Examples of patterns that provoked this bug (shown in
193        pcretest format) are:
195          /(?-x: )/x
196          /(?x)(?-x: \s*#\s*)/
197          /((?i)[\x{c0}])/8
198          /(?i:[\x{c0}])/8
200        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
201        is now done differently.
203     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
204        wrapper classes; (b) implement a new function in the C++ scanner that is
205        more efficient than the old way of doing things because it avoids levels of
206        recursion in the regex matching; (c) add a paragraph to the documentation
207        for the FullMatch() function.
209     6. The escape sequence \n was being treated as whatever was defined as
210        "newline". Not only was this contrary to the documentation, which states
211        that \n is character 10 (hex 0A), but it also went horribly wrong when
212        "newline" was defined as CRLF. This has been fixed.
214     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
215        was being set to -1 for the "end of line" case (supposedly a value that no
216        character can have). Though this value is never used (the check for end of
217        line is "zero bytes in current character"), it caused compiler complaints.
218        I've changed it to 0xffffffff.
220     8. In pcre_version.c, the version string was being built by a sequence of
221        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
222        string (as it is for production releases) called a macro with an empty
223        argument. The C standard says the result of this is undefined. The gcc
224        compiler treats it as an empty string (which was what was wanted) but it is
225        reported that Visual C gives an error. The source has been hacked around to
226        avoid this problem.
228     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
229        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
230        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
231        of them did).
233    10. Originally, pcretest opened its input and output without "b"; then I was
234        told that "b" was needed in some environments, so it was added for release
235        5.0 to both the input and output. (It makes no difference on Unix-like
236        systems.) Later I was told that it is wrong for the input on Windows. I've
237        now abstracted the modes into two macros, to make it easier to fiddle with
238        them, and removed "b" from the input mode under Windows.
240    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
242    12. Added -help and --help to pcretest as an official way of being reminded
243        of the options.
245    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
246        and pcrecpp.cc because they annoy compilers at high warning levels.
248    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
250    15. Fixed an occurrence of == in configure.ac that should have been = (shell
251        scripts are not C programs :-) and which was not noticed because it works
252        on Linux.
254    16. pcretest is supposed to handle any length of pattern and data line (as one
255        line or as a continued sequence of lines) by extending its input buffer if
256        necessary. This feature was broken for very long pattern lines, leading to
257        a string of junk being passed to pcre_compile() if the pattern was longer
258        than about 50K.
260    17. I have done a major re-factoring of the way pcre_compile() computes the
261        amount of memory needed for a compiled pattern. Previously, there was code
262        that made a preliminary scan of the pattern in order to do this. That was
263        OK when PCRE was new, but as the facilities have expanded, it has become
264        harder and harder to keep it in step with the real compile phase, and there
265        have been a number of bugs (see for example, 4 above). I have now found a
266        cunning way of running the real compile function in a "fake" mode that
267        enables it to compute how much memory it would need, while actually only
268        ever using a few hundred bytes of working memory and without too many
269        tests of the mode. This should make future maintenance and development
270        easier. A side effect of this work is that the limit of 200 on the nesting
271        depth of parentheses has been removed (though this was never a serious
272        limitation, I suspect). However, there is a downside: pcre_compile() now
273        runs more slowly than before (30% or more, depending on the pattern). I
274        hope this isn't a big issue. There is no effect on runtime performance.
276    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
277        newline (only possible for the last line of a file) and it was a
278        pattern that set a locale (followed by /Lsomething), pcretest crashed.
280    19. Added additional timing features to pcretest. (1) The -tm option now times
281        matching only, not compiling. (2) Both -t and -tm can be followed, as a
282        separate command line item, by a number that specifies the number of
283        repeats to use when timing. The default is 50000; this gives better
284        precision, but takes uncomfortably long for very large patterns.
286    20. Extended pcre_study() to be more clever in cases where a branch of a
287        subpattern has no definite first character. For example, (a*|b*)[cd] would
288        previously give no result from pcre_study(). Now it recognizes that the
289        first character must be a, b, c, or d.
291    21. There was an incorrect error "recursive call could loop indefinitely" if
292        a subpattern (or the entire pattern) that was being tested for matching an
293        empty string contained only one non-empty item after a nested subpattern.
294        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
295        incorrectly, because the \d was being skipped in the check.
297    22. The pcretest program now has a new pattern option /B and a command line
298        option -b, which is equivalent to adding /B to every pattern. This causes
299        it to show the compiled bytecode, without the additional information that
300        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
301        is the same as /B/I).
303    23. A new optimization is now able automatically to treat some sequences such
304        as a*b as a*+b. More specifically, if something simple (such as a character
305        or a simple class like \d) has an unlimited quantifier, and is followed by
306        something that cannot possibly match the quantified thing, the quantifier
307        is automatically "possessified".
309    24. A recursive reference to a subpattern whose number was greater than 39
310        went wrong under certain circumstances in UTF-8 mode. This bug could also
311        have affected the operation of pcre_study().
313    25. Realized that a little bit of performance could be had by replacing
314        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
316    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
318    27. Possessive quantifiers such as a++ were previously implemented by turning
319        them into atomic groups such as ($>a+). Now they have their own opcodes,
320        which improves performance. This includes the automatically created ones
321        from 23 above.
323    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
324        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
325        the first matched character to be a colon. This applied both to named and
326        numbered groups.
328    29. The ucpinternal.h header file was missing its idempotency #ifdef.
330    30. I was sent a "project" file called libpcre.a.dev which I understand makes
331        building PCRE on Windows easier, so I have included it in the distribution.
333    31. There is now a check in pcretest against a ridiculously large number being
334        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
335        loop, the loop is abandoned.
337    32. Forward references to subpatterns in conditions such as (?(2)...) where
338        subpattern 2 is defined later cause pcre_compile() to search forwards in
339        the pattern for the relevant set of parentheses. This search went wrong
340        when there were unescaped parentheses in a character class, parentheses
341        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
343    33. "Subroutine" calls and backreferences were previously restricted to
344        referencing subpatterns earlier in the regex. This restriction has now
345        been removed.
347    34. Added a number of extra features that are going to be in Perl 5.10. On the
348        whole, these are just syntactic alternatives for features that PCRE had
349        previously implemented using the Python syntax or my own invention. The
350        other formats are all retained for compatibility.
352        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
353            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
354            also .NET compatible.
356        (b) A recursion or subroutine call to a named group can now be defined as
357            (?&name) as well as (?P>name).
359        (c) A backreference to a named group can now be defined as \k<name> or
360            \k'name' as well as (?P=name). The new forms, as well as being in Perl
361            5.10, are also .NET compatible.
363        (d) A conditional reference to a named group can now use the syntax
364            (?(<name>) or (?('name') as well as (?(name).
366        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
367            groups (named and numbered) that are never evaluated inline, but can be
368            called as "subroutines" from elsewhere. In effect, the DEFINE condition
369            is always false. There may be only one alternative in such a group.
371        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
372            as the simple (?(R). The condition is true only if the most recent
373            recursion is that of the given number or name. It does not search out
374            through the entire recursion stack.
376        (g) The escape \gN or \g{N} has been added, where N is a positive or
377            negative number, specifying an absolute or relative reference.
379    35. Tidied to get rid of some further signed/unsigned compiler warnings and
380        some "unreachable code" warnings.
382    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
383        things, this adds five new scripts.
385    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
386        There were also incompatibilities regarding the handling of \Q..\E inside
387        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
388        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
390    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
391        matches an empty string, and forcibly breaks the loop. There were bugs in
392        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
393        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
394        separate and independent bugs (that affected different cases) have been
395        fixed.
397    39. Refactored the code to abolish the use of different opcodes for small
398        capturing bracket numbers. This is a tidy that I avoided doing when I
399        removed the limit on the number of capturing brackets for 3.5 back in 2001.
400        The new approach is not only tidier, it makes it possible to reduce the
401        memory needed to fix the previous bug (38).
403    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
404        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
405        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
406        mode.
408    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
409        report.
411    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
412        copy construction and assignment in the C++ wrapper.
414    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
415        couple of bugs that could have given wrong results in the "--newline=crlf"
416        case.
418    44. Added a number of casts and did some reorganization of signed/unsigned int
419        variables following suggestions from Dair Grant. Also renamed the variable
420        "this" as "item" because it is a C++ keyword.
422    45. Arranged for dftables to add
424          #include "pcre_internal.h"
426        to pcre_chartables.c because without it, gcc 4.x may remove the array
427        definition from the final binary if PCRE is built into a static library and
428        dead code stripping is activated.
430    46. For an unanchored pattern, if a match attempt fails at the start of a
431        newline sequence, and the newline setting is CRLF or ANY, and the next two
432        characters are CRLF, advance by two characters instead of one.
435    Version 6.7 04-Jul-06
436    ---------------------
438     1. In order to handle tests when input lines are enormously long, pcretest has
439        been re-factored so that it automatically extends its buffers when
440        necessary. The code is crude, but this _is_ just a test program. The
441        default size has been increased from 32K to 50K.
443     2. The code in pcre_study() was using the value of the re argument before
444        testing it for NULL. (Of course, in any sensible call of the function, it
445        won't be NULL.)
447     3. The memmove() emulation function in pcre_internal.h, which is used on
448        systems that lack both memmove() and bcopy() - that is, hardly ever -
449        was missing a "static" storage class specifier.
451     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
452        containing an extended class (one that cannot be represented by a bitmap
453        because it contains high-valued characters or Unicode property items, e.g.
454        [\pZ]). Almost always one would set UTF-8 mode when processing such a
455        pattern, but PCRE should not loop if you do not (it no longer does).
456        [Detail: two cases were found: (a) a repeated subpattern containing an
457        extended class; (b) a recursive reference to a subpattern that followed a
458        previous extended class. It wasn't skipping over the extended class
459        correctly when UTF-8 mode was not set.]
461     5. A negated single-character class was not being recognized as fixed-length
462        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
463        compile error "lookbehind assertion is not fixed length".
465     6. The RunPerlTest auxiliary script was showing an unexpected difference
466        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
467        write a Perl script that can interpret lines of an input file either as
468        byte characters or as UTF-8, which is what "perltest" was being required to
469        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
470        can't do is switch easily at run time between having the "use utf8;" pragma
471        or not. In the end, I fudged it by using the RunPerlTest script to insert
472        "use utf8;" explicitly for the UTF-8 tests.
474     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
475        the end of the subject string, contrary to the documentation and to what
476        Perl does. This was true of both matching functions. Now it matches only at
477        the start of the subject and immediately after *internal* newlines.
479     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
480        a pointer to an int instead of a pointer to an unsigned long int. This
481        caused problems on 64-bit systems.
483     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
484        instance of the 'standard' template library not being so standard".
486    10. There was no check on the number of named subpatterns nor the maximum
487        length of a subpattern name. The product of these values is used to compute
488        the size of the memory block for a compiled pattern. By supplying a very
489        long subpattern name and a large number of named subpatterns, the size
490        computation could be caused to overflow. This is now prevented by limiting
491        the length of names to 32 characters, and the number of named subpatterns
492        to 10,000.
494    11. Subpatterns that are repeated with specific counts have to be replicated in
495        the compiled pattern. The size of memory for this was computed from the
496        length of the subpattern and the repeat count. The latter is limited to
497        65535, but there was no limit on the former, meaning that integer overflow
498        could in principle occur. The compiled length of a repeated subpattern is
499        now limited to 30,000 bytes in order to prevent this.
501    12. Added the optional facility to have named substrings with the same name.
503    13. Added the ability to use a named substring as a condition, using the
504        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
505        are numbers (not recommended). Forward references are permitted.
507    14. Added forward references in named backreferences (if you see what I mean).
509    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
510        pattern could run off the end of the subject. For example, the pattern
511        "(?s)(.{1,5})"8 did this with the subject "ab".
513    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
514        PCRE_CASELESS was set when matching characters that were quantified with ?
515        or *.
517    17. A character class other than a single negated character that had a minimum
518        but no maximum quantifier - for example [ab]{6,} - was not handled
519        correctly by pce_dfa_exec(). It would match only one character.
521    18. A valid (though odd) pattern that looked like a POSIX character
522        class but used an invalid character after [ (for example [[,abc,]]) caused
523        pcre_compile() to give the error "Failed: internal error: code overflow" or
524        in some cases to crash with a glibc free() error. This could even happen if
525        the pattern terminated after [[ but there just happened to be a sequence of
526        letters, a binary zero, and a closing ] in the memory that followed.
528    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
529        over the years. Originally (before any Unicode support), just the bottom 8
530        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
531        output from "man perlunicode" includes this:
533          The regular expression compiler produces polymorphic opcodes.  That
534          is, the pattern adapts to the data and automatically switches to
535          the Unicode character scheme when presented with Unicode data--or
536          instead uses a traditional byte scheme when presented with byte
537          data.
539        Sadly, a wide octal escape does not cause a switch, and in a string with
540        no other multibyte characters, these octal escapes are treated as before.
541        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
542        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
543        Unicode string.
545        I have not perpetrated such confusion in PCRE. Up till now, it took just
546        the bottom 8 bits, as in old Perl. I have now made octal escapes with
547        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
548        translate to the appropriate multibyte character.
550    29. Applied some refactoring to reduce the number of warnings from Microsoft
551        and Borland compilers. This has included removing the fudge introduced
552        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
553        a warning about an unused variable.
555    21. PCRE has not included VT (character 0x0b) in the set of whitespace
556        characters since release 4.0, because Perl (from release 5.004) does not.
557        [Or at least, is documented not to: some releases seem to be in conflict
558        with the documentation.] However, when a pattern was studied with
559        pcre_study() and all its branches started with \s, PCRE still included VT
560        as a possible starting character. Of course, this did no harm; it just
561        caused an unnecessary match attempt.
563    22. Removed a now-redundant internal flag bit that recorded the fact that case
564        dependency changed within the pattern. This was once needed for "required
565        byte" processing, but is no longer used. This recovers a now-scarce options
566        bit. Also moved the least significant internal flag bit to the most-
567        significant bit of the word, which was not previously used (hangover from
568        the days when it was an int rather than a uint) to free up another bit for
569        the future.
571    23. Added support for CRLF line endings as well as CR and LF. As well as the
572        default being selectable at build time, it can now be changed at runtime
573        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
574        specify that it is scanning data with non-default line endings.
576    24. Changed the definition of CXXLINK to make it agree with the definition of
577        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
579    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
580        recursions. This makes a big different to stack usage for some patterns.
582    26. If a subpattern containing a named recursion or subroutine reference such
583        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
584        the space required for the compiled pattern went wrong and gave too small a
585        value. Depending on the environment, this could lead to "Failed: internal
586        error: code overflow at offset 49" or "glibc detected double free or
587        corruption" errors.
589    27. Applied patches from Google (a) to support the new newline modes and (b) to
590        advance over multibyte UTF-8 characters in GlobalReplace.
592    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
593        difference for some implementation of PCRE in some Windows version.
595    29. Added some extra testing facilities to pcretest:
597        \q<number>   in a data line sets the "match limit" value
598        \Q<number>   in a data line sets the "match recursion limt" value
599        -S <number>  sets the stack size, where <number> is in megabytes
601        The -S option isn't available for Windows.
604    Version 6.6 06-Feb-06
605    ---------------------
607     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
608        in pcreposix.h. I have copied the definition from pcre.h.
610     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
611        because pcre.h is no longer a built file.
613     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
614        not normally included in the compiled code.
617    Version 6.5 01-Feb-06
618    ---------------------
620     1. When using the partial match feature with pcre_dfa_exec(), it was not
621        anchoring the second and subsequent partial matches at the new starting
622        point. This could lead to incorrect results. For example, with the pattern
623        /1234/, partially matching against "123" and then "a4" gave a match.
625     2. Changes to pcregrep:
627        (a) All non-match returns from pcre_exec() were being treated as failures
628            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
629            error message is output. Some extra information is given for the
630            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
631            probably the only errors that are likely to be caused by users (by
632            specifying a regex that has nested indefinite repeats, for instance).
633            If there are more than 20 of these errors, pcregrep is abandoned.
635        (b) A binary zero was treated as data while matching, but terminated the
636            output line if it was written out. This has been fixed: binary zeroes
637            are now no different to any other data bytes.
639        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
640            used to set a locale for matching. The --locale=xxxx long option has
641            been added (no short equivalent) to specify a locale explicitly on the
642            pcregrep command, overriding the environment variables.
644        (d) When -B was used with -n, some line numbers in the output were one less
645            than they should have been.
647        (e) Added the -o (--only-matching) option.
649        (f) If -A or -C was used with -c (count only), some lines of context were
650            accidentally printed for the final match.
652        (g) Added the -H (--with-filename) option.
654        (h) The combination of options -rh failed to suppress file names for files
655            that were found from directory arguments.
657        (i) Added the -D (--devices) and -d (--directories) options.
659        (j) Added the -F (--fixed-strings) option.
661        (k) Allow "-" to be used as a file name for -f as well as for a data file.
663        (l) Added the --colo(u)r option.
665        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
666            is not present by default.
668     3. A nasty bug was discovered in the handling of recursive patterns, that is,
669        items such as (?R) or (?1), when the recursion could match a number of
670        alternatives. If it matched one of the alternatives, but subsequently,
671        outside the recursion, there was a failure, the code tried to back up into
672        the recursion. However, because of the way PCRE is implemented, this is not
673        possible, and the result was an incorrect result from the match.
675        In order to prevent this happening, the specification of recursion has
676        been changed so that all such subpatterns are automatically treated as
677        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
679     4. I had overlooked the fact that, in some locales, there are characters for
680        which isalpha() is true but neither isupper() nor islower() are true. In
681        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
682        and ordfeminine) are like this. This affected the treatment of \w and \W
683        when they appeared in character classes, but not when they appeared outside
684        a character class. The bit map for "word" characters is now created
685        separately from the results of isalnum() instead of just taking it from the
686        upper, lower, and digit maps. (Plus the underscore character, of course.)
688     5. The above bug also affected the handling of POSIX character classes such as
689        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
690        permanent tables. Instead, the bit maps for such a class were previously
691        created as the appropriate unions of the upper, lower, and digit bitmaps.
692        Now they are created by subtraction from the [[:word:]] class, which has
693        its own bitmap.
695     6. The [[:blank:]] character class matches horizontal, but not vertical space.
696        It is created by subtracting the vertical space characters (\x09, \x0a,
697        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
698        subtraction was done in the overall bitmap for a character class, meaning
699        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
700        be recognized. This bug has been fixed.
702     7. Patches from the folks at Google:
704          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
705          real life, but is still worth protecting against".
707          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
708          regular expressions".
710          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
711          have it.
713          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
714          "configure" and the latter not, in order to fix a problem somebody had
715          with compiling the Arg class on HP-UX.
717          (e) Improve the error-handling of the C++ wrapper a little bit.
719          (f) New tests for checking recursion limiting.
721     8. The pcre_memmove() function, which is used only if the environment does not
722        have a standard memmove() function (and is therefore rarely compiled),
723        contained two bugs: (a) use of int instead of size_t, and (b) it was not
724        returning a result (though PCRE never actually uses the result).
726     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
727        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
728        returned instead of calling malloc() with an overflowing number that would
729        most likely cause subsequent chaos.
731    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
733    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
734        with this option is matched, the nmatch and pmatch options of regexec() are
735        ignored.
737    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
738        provided in case anyone wants to the the POSIX interface with UTF-8
739        strings.
741    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
742        C++ linking (needed for some HP-UX environments).
744    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
745        (unused parameter) and in the pcre_printint() function (omitted "default"
746        switch label when the default is to do nothing).
748    15. Added some code to make it possible, when PCRE is compiled as a C++
749        library, to replace subject pointers for pcre_exec() with a smart pointer
750        class, thus making it possible to process discontinuous strings.
752    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
753        much the same function. They were added by different people who were trying
754        to make PCRE easy to compile on non-Unix systems. It has been suggested
755        that PCRE_EXPORT be abolished now that there is more automatic apparatus
756        for compiling on Windows systems. I have therefore replaced it with
757        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
758        defaults to "extern" for C or "extern C" for C++, which works fine on
759        Unix-like systems. It is now possible to override the value of PCRE_DATA_
760        SCOPE with something explicit in config.h. In addition:
762        (a) pcreposix.h still had just "extern" instead of either of these macros;
763            I have replaced it with PCRE_DATA_SCOPE.
765        (b) Functions such as _pcre_xclass(), which are internal to the library,
766            but external in the C sense, all had PCRE_EXPORT in their definitions.
767            This is apparently wrong for the Windows case, so I have removed it.
768            (It makes no difference on Unix-like systems.)
770    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
771        of recursive calls to match(). This is different to MATCH_LIMIT because
772        that limits the total number of calls to match(), not all of which increase
773        the depth of recursion. Limiting the recursion depth limits the amount of
774        stack (or heap if NO_RECURSE is set) that is used. The default can be set
775        when PCRE is compiled, and changed at run time. A patch from Google adds
776        this functionality to the C++ interface.
778    18. Changes to the handling of Unicode character properties:
780        (a) Updated the table to Unicode 4.1.0.
782        (b) Recognize characters that are not in the table as "Cn" (undefined).
784        (c) I revised the way the table is implemented to a much improved format
785            which includes recognition of ranges. It now supports the ranges that
786            are defined in UnicodeData.txt, and it also amalgamates other
787            characters into ranges. This has reduced the number of entries in the
788            table from around 16,000 to around 3,000, thus reducing its size
789            considerably. I realized I did not need to use a tree structure after
790            all - a binary chop search is just as efficient. Having reduced the
791            number of entries, I extended their size from 6 bytes to 8 bytes to
792            allow for more data.
794        (d) Added support for Unicode script names via properties such as \p{Han}.
796    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
797        matching that character.
799    20. When matching a repeated Unicode property with a minimum greater than zero,
800        (for example \pL{2,}), PCRE could look past the end of the subject if it
801        reached it while seeking the minimum number of characters. This could
802        happen only if some of the characters were more than one byte long, because
803        there is a check for at least the minimum number of bytes.
805    21. Refactored the implementation of \p and \P so as to be more general, to
806        allow for more different types of property in future. This has changed the
807        compiled form incompatibly. Anybody with saved compiled patterns that use
808        \p or \P will have to recompile them.
810    22. Added "Any" and "L&" to the supported property types.
812    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
813        but give a compile time error if the value is greater than 0xff.
815    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
816        accidentally not being installed or uninstalled.
818    25. The pcre.h file was built from pcre.h.in, but the only changes that were
819        made were to insert the current release number. This seemed silly, because
820        it made things harder for people building PCRE on systems that don't run
821        "configure". I have turned pcre.h into a distributed file, no longer built
822        by "configure", with the version identification directly included. There is
823        no longer a pcre.h.in file.
825        However, this change necessitated a change to the pcre-config script as
826        well. It is built from pcre-config.in, and one of the substitutions was the
827        release number. I have updated configure.ac so that ./configure now finds
828        the release number by grepping pcre.h.
830    26. Added the ability to run the tests under valgrind.
833    Version 6.4 05-Sep-05
834    ---------------------
836     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
837        "--" to be printed when multiple files were scanned, even when none of the
838        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
839        consider it to be a bug, and have restored the previous behaviour.
841     2. A couple of code tidies to get rid of compiler warnings.
843     3. The pcretest program used to cheat by referring to symbols in the library
844        whose names begin with _pcre_. These are internal symbols that are not
845        really supposed to be visible externally, and in some environments it is
846        possible to suppress them. The cheating is now confined to including
847        certain files from the library's source, which is a bit cleaner.
849     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
850        file's purpose clearer.
852     5. Reorganized pcre_ucp_findchar().
855    Version 6.3 15-Aug-05
856    ---------------------
858     1. The file libpcre.pc.in did not have general read permission in the tarball.
860     2. There were some problems when building without C++ support:
862        (a) If C++ support was not built, "make install" and "make test" still
863            tried to test it.
865        (b) There were problems when the value of CXX was explicitly set. Some
866            changes have been made to try to fix these, and ...
868        (c) --disable-cpp can now be used to explicitly disable C++ support.
870        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
871            backslash in a target when C++ was disabled. This confuses some
872            versions of "make", apparently. Using an intermediate variable solves
873            this. (Same for CPP_LOBJ.)
875     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
876        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
877        necessary on certain architectures.
879     4. Added a setting of -export-symbols-regex to the link command to remove
880        those symbols that are exported in the C sense, but actually are local
881        within the library, and not documented. Their names all begin with
882        "_pcre_". This is not a perfect job, because (a) we have to except some
883        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
884        available (and never for static libraries). I have made a note to try to
885        find a way round (a) in the future.
888    Version 6.2 01-Aug-05
889    ---------------------
891     1. There was no test for integer overflow of quantifier values. A construction
892        such as {1111111111111111} would give undefined results. What is worse, if
893        a minimum quantifier for a parenthesized subpattern overflowed and became
894        negative, the calculation of the memory size went wrong. This could have
895        led to memory overwriting.
897     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
899     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
900        operating environments where this matters.
902     4. Applied Giuseppe Maxia's patch to add additional features for controlling
903        PCRE options from within the C++ wrapper.
905     5. Named capturing subpatterns were not being correctly counted when a pattern
906        was compiled. This caused two problems: (a) If there were more than 100
907        such subpatterns, the calculation of the memory needed for the whole
908        compiled pattern went wrong, leading to an overflow error. (b) Numerical
909        back references of the form \12, where the number was greater than 9, were
910        not recognized as back references, even though there were sufficient
911        previous subpatterns.
913     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
914        versions of gcc, e.g. 2.95.4.
917    Version 6.1 21-Jun-05
918    ---------------------
920     1. There was one reference to the variable "posix" in pcretest.c that was not
921        surrounded by "#if !defined NOPOSIX".
923     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
924        the cross-check on the old pcre_info() function, for the benefit of the
925        cut-down version of PCRE that is currently imported into Exim.
927     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
928        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
929        patterns that start (?i) but I don't think that matters. The use of (?i) is
930        just an example; this all applies to the other options as well.
932     4. Since libtool seems to echo the compile commands it is issuing, the output
933        from "make" can be reduced a bit by putting "@" in front of each libtool
934        compile command.
936     5. Patch from the folks at Google for configure.in to be a bit more thorough
937        in checking for a suitable C++ installation before trying to compile the
938        C++ stuff. This should fix a reported problem when a compiler was present,
939        but no suitable headers.
941     6. The man pages all had just "PCRE" as their title. I have changed them to
942        be the relevant file name. I have also arranged that these names are
943        retained in the file doc/pcre.txt, which is a concatenation in text format
944        of all the man pages except the little individual ones for each function.
946     7. The NON-UNIX-USE file had not been updated for the different set of source
947        files that come with release 6. I also added a few comments about the C++
948        wrapper.
951    Version 6.0 07-Jun-05
952    ---------------------
954     1. Some minor internal re-organization to help with my DFA experiments.
956     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
957        didn't matter for the library itself when fully configured, but did matter
958        when compiling without UCP support, or within Exim, where the ucp files are
959        not imported.
961     3. Refactoring of the library code to split up the various functions into
962        different source modules. The addition of the new DFA matching code (see
963        below) to a single monolithic source would have made it really too
964        unwieldy, quite apart from causing all the code to be include in a
965        statically linked application, when only some functions are used. This is
966        relevant even without the DFA addition now that patterns can be compiled in
967        one application and matched in another.
969        The downside of splitting up is that there have to be some external
970        functions and data tables that are used internally in different modules of
971        the library but which are not part of the API. These have all had their
972        names changed to start with "_pcre_" so that they are unlikely to clash
973        with other external names.
975     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
976        a different (DFA) algorithm. Although it is slower than the original
977        function, it does have some advantages for certain types of matching
978        problem.
980     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
981        including restarting after a partial match.
983     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
984        defined when compiling for Windows was sent to me. I have put it into the
985        code, though I have no means of testing or verifying it.
987     7. Added the pcre_refcount() auxiliary function.
989     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
990        match before or at the first newline in the subject string. In pcretest,
991        the /f option on a pattern can be used to set this.
993     9. A repeated \w when used in UTF-8 mode with characters greater than 256
994        would behave wrongly. This has been present in PCRE since release 4.0.
996    10. A number of changes to the pcregrep command:
998        (a) Refactored how -x works; insert ^(...)$ instead of setting
999            PCRE_ANCHORED and checking the length, in preparation for adding
1000            something similar for -w.
1002        (b) Added the -w (match as a word) option.
1004        (c) Refactored the way lines are read and buffered so as to have more
1005            than one at a time available.
1007        (d) Implemented a pcregrep test script.
1009        (e) Added the -M (multiline match) option. This allows patterns to match
1010            over several lines of the subject. The buffering ensures that at least
1011            8K, or the rest of the document (whichever is the shorter) is available
1012            for matching (and similarly the previous 8K for lookbehind assertions).
1014        (f) Changed the --help output so that it now says
1016              -w, --word-regex(p)
1018            instead of two lines, one with "regex" and the other with "regexp"
1019            because that confused at least one person since the short forms are the
1020            same. (This required a bit of code, as the output is generated
1021            automatically from a table. It wasn't just a text change.)
1023        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1024            option but starts with a hyphen. Could be a pattern or a path name
1025            starting with a hyphen, for instance.
1027        (h) "-" can be given as a file name to represent stdin.
1029        (i) When file names are being printed, "(standard input)" is used for
1030            the standard input, for compatibility with GNU grep. Previously
1031            "<stdin>" was used.
1033        (j) The option --label=xxx can be used to supply a name to be used for
1034            stdin when file names are being printed. There is no short form.
1036        (k) Re-factored the options decoding logic because we are going to add
1037            two more options that take data. Such options can now be given in four
1038            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1040        (l) Added the -A, -B, and -C options for requesting that lines of context
1041            around matches be printed.
1043        (m) Added the -L option to print the names of files that do not contain
1044            any matching lines, that is, the complement of -l.
1046        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1047            continue to scan other files.
1049        (o) The -s option was incorrectly implemented. For compatibility with other
1050            greps, it now suppresses the error message for a non-existent or non-
1051            accessible file (but not the return code). There is a new option called
1052            -q that suppresses the output of matching lines, which was what -s was
1053            previously doing.
1055        (p) Added --include and --exclude options to specify files for inclusion
1056            and exclusion when recursing.
1058    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1059        Hopefully, it now does.
1061    12. Missing cast in pcre_study().
1063    13. Added an "uninstall" target to the makefile.
1065    14. Replaced "extern" in the function prototypes in Makefile.in with
1066        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1067        world, but is set differently for Windows.
1069    15. Added a second compiling function called pcre_compile2(). The only
1070        difference is that it has an extra argument, which is a pointer to an
1071        integer error code. When there is a compile-time failure, this is set
1072        non-zero, in addition to the error test pointer being set to point to an
1073        error message. The new argument may be NULL if no error number is required
1074        (but then you may as well call pcre_compile(), which is now just a
1075        wrapper). This facility is provided because some applications need a
1076        numeric error indication, but it has also enabled me to tidy up the way
1077        compile-time errors are handled in the POSIX wrapper.
1079    16. Added VPATH=.libs to the makefile; this should help when building with one
1080        prefix path and installing with another. (Or so I'm told by someone who
1081        knows more about this stuff than I do.)
1083    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1084        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1085        match everything, including newlines. This is not POSIX-compatible, but
1086        somebody wanted the feature. From pcretest it can be activated by using
1087        both the P and the s flags.
1089    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1091    19. libpcre.pc was being incorrectly installed as executable.
1093    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1094        it now also looks for '\r' so that it will work unmodified on Windows.
1096    21. Added Google's contributed C++ wrapper to the distribution.
1098    22. Added some untidy missing memory free() calls in pcretest, to keep
1099        Electric Fence happy when testing.
1103    Version 5.0 13-Sep-04
1104    ---------------------
1106     1. Internal change: literal characters are no longer packed up into items
1107        containing multiple characters in a single byte-string. Each character
1108        is now matched using a separate opcode. However, there may be more than one
1109        byte in the character in UTF-8 mode.
1111     2. The pcre_callout_block structure has two new fields: pattern_position and
1112        next_item_length. These contain the offset in the pattern to the next match
1113        item, and its length, respectively.
1115     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1116        insertion of callouts before each pattern item. Added the /C option to
1117        pcretest to make use of this.
1119     4. On the advice of a Windows user, the lines
1121          #if defined(_WIN32) || defined(WIN32)
1122          _setmode( _fileno( stdout ), 0x8000 );
1123          #endif  /* defined(_WIN32) || defined(WIN32) */
1125        have been added to the source of pcretest. This apparently does useful
1126        magic in relation to line terminators.
1128     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1129        for the benefit of those environments where the "b" makes a difference.
1131     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1132        to know about it. I have put a hack into configure.in that adds in code
1133        to set GCC=yes if CC=icc. This seems to end up at a point in the
1134        generated configure script that is early enough to affect the setting of
1135        compiler options, which is what is needed, but I have no means of testing
1136        whether it really works. (The user who reported this had patched the
1137        generated configure script, which of course I cannot do.)
1139        LATER: After change 22 below (new libtool files), the configure script
1140        seems to know about icc (and also ecc). Therefore, I have commented out
1141        this hack in configure.in.
1143     7. Added support for pkg-config (2 patches were sent in).
1145     8. Negated POSIX character classes that used a combination of internal tables
1146        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1147        [[:^ascii]]. Typically, they would match almost any characters. The other
1148        POSIX classes were not broken in this way.
1150     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1151        to find the match, as PCRE was deluded into thinking that the match had to
1152        start at the start point or following a newline. The same bug applied to
1153        patterns with negative forward assertions or any backward assertions
1154        preceding ".*" at the start, unless the pattern required a fixed first
1155        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1157    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1158        starting at the last subject character, bytes beyond the end of the subject
1159        string were read.
1161    11. Renamed the variable "class" as "classbits" to make life easier for C++
1162        users. (Previously there was a macro definition, but it apparently wasn't
1163        enough.)
1165    12. Added the new field "tables" to the extra data so that tables can be passed
1166        in at exec time, or the internal tables can be re-selected. This allows
1167        a compiled regex to be saved and re-used at a later time by a different
1168        program that might have everything at different addresses.
1170    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1171        -R library as well as a -L library.
1173    14. The debugging options of pcretest (-d on the command line or D on a
1174        pattern) showed incorrect output for anything following an extended class
1175        that contained multibyte characters and which was followed by a quantifier.
1177    15. Added optional support for general category Unicode character properties
1178        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1179        support. It adds about 90K to the size of the library. The meanings of the
1180        inbuilt class escapes such as \d and \s have NOT been changed.
1182    16. Updated pcredemo.c to include calls to free() to release the memory for the
1183        compiled pattern.
1185    17. The generated file chartables.c was being created in the source directory
1186        instead of in the building directory. This caused the build to fail if the
1187        source directory was different from the building directory, and was
1188        read-only.
1190    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1191        file. No doubt somebody will tell me if they don't make sense... Also added
1192        Dan Mooney's comments about building on OpenVMS.
1194    19. Added support for partial matching via the PCRE_PARTIAL option for
1195        pcre_exec() and the \P data escape in pcretest.
1197    20. Extended pcretest with 3 new pattern features:
1199        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1200              write the compiled pattern to the file whose name is "rest-of-line".
1201              This is a straight binary dump of the data, with the saved pointer to
1202              the character tables forced to be NULL. The study data, if any, is
1203              written too. After writing, pcretest reads a new pattern.
1205        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1206              compiled pattern from the given file. There must not be any
1207              occurrences of "<" in the file name (pretty unlikely); if there are,
1208              pcretest will instead treat the initial "<" as a pattern delimiter.
1209              After reading in the pattern, pcretest goes on to read data lines as
1210              usual.
1212        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1213              and 16-bit fields in a compiled pattern, to simulate a pattern that
1214              was compiled on a host of opposite endianness.
1216    21. The pcre-exec() function can now cope with patterns that were compiled on
1217        hosts of opposite endianness, with this restriction:
1219          As for any compiled expression that is saved and used later, the tables
1220          pointer field cannot be preserved; the extra_data field in the arguments
1221          to pcre_exec() should be used to pass in a tables address if a value
1222          other than the default internal tables were used at compile time.
1224    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1225        now diagnosed as an error. Previously, most of the time, a negative number
1226        would have been treated as zero, but if in addition "ovector" was passed as
1227        NULL, a crash could occur.
1229    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1230        new versions from the libtool 1.5 distribution (the last one is a copy of
1231        a file called libtool.m4). This seems to have fixed the need to patch
1232        "configure" to support Darwin 1.3 (which I used to do). However, I still
1233        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1234        workstation).
1236    24. Changed the PCRE licence to be the more standard "BSD" licence.
1239    Version 4.5 01-Dec-03
1240    ---------------------
1242     1. There has been some re-arrangement of the code for the match() function so
1243        that it can be compiled in a version that does not call itself recursively.
1244        Instead, it keeps those local variables that need separate instances for
1245        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1246        needs to "recurse". Keeping track of where control must go is done by means
1247        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1248        hide most of the details from the main code, and operates only if
1249        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1250        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1251        operating.
1253        To make it easier for callers to provide specially tailored get/free
1254        functions for this usage, two new functions, pcre_stack_malloc, and
1255        pcre_stack_free, are used. They are always called in strict stacking order,
1256        and the size of block requested is always the same.
1258        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1259        PCRE has been compiled to use the stack or the heap for recursion. The
1260        -C option of pcretest uses this to show which version is compiled.
1262        A new data escape \S, is added to pcretest; it causes the amounts of store
1263        obtained and freed by both kinds of malloc/free at match time to be added
1264        to the output.
1266     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1267        what's available on my current Linux desktop machine.
1269     3. When matching a UTF-8 string, the test for a valid string at the start has
1270        been extended. If start_offset is not zero, PCRE now checks that it points
1271        to a byte that is the start of a UTF-8 character. If not, it returns
1272        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1273        this is necessary because there may be backward assertions in the pattern.
1274        When matching the same subject several times, it may save resources to use
1275        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1277     4. The code for checking the validity of UTF-8 strings has been tightened so
1278        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1279        containing "overlong sequences".
1281     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1282        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1283        should have been "&", but it just so happened that all the cases this let
1284        through by mistake were picked up later in the function.
1286     6. I had used a variable called "isblank" - this is a C99 function, causing
1287        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1289     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1290        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1291        so the version is shown; (c) stop "make test" echoing "./RunTest".
1293     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1295     9. The prototype for memmove() for systems that don't have it was using
1296        size_t, but the inclusion of the header that defines size_t was later. I've
1297        moved the #includes for the C headers earlier to avoid this.
1299    10. Added some adjustments to the code to make it easier to compiler on certain
1300        special systems:
1302          (a) Some "const" qualifiers were missing.
1303          (b) Added the macro EXPORT before all exported functions; by default this
1304              is defined to be empty.
1305          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1306              that it reads its output file name as an argument instead of writing
1307              to the standard output and assuming this can be redirected.
1309    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1310        class containing characters with values greater than 255, PCRE compilation
1311        went into a loop.
1313    12. A recursive reference to a subpattern that was within another subpattern
1314        that had a minimum quantifier of zero caused PCRE to crash. For example,
1315        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1316        recursion. If the recursively-called subpattern itself had a zero repeat,
1317        that was OK.
1319    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1320        buffer into which it was copied (for escape processing) was still set at
1321        1024, so long lines caused crashes.
1323    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1324        "internal error: code overflow...". This applied to any character class
1325        that was followed by a possessive quantifier.
1327    15. Modified the Makefile to add libpcre.la as a prerequisite for
1328        libpcreposix.la because I was told this is needed for a parallel build to
1329        work.
1331    16. If a pattern that contained .* following optional items at the start was
1332        studied, the wrong optimizing data was generated, leading to matching
1333        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1334        matching string must start with a or b or c. The correct conclusion for
1335        this pattern is that a match can start with any character.
1338    Version 4.4 13-Aug-03
1339    ---------------------
1341     1. In UTF-8 mode, a character class containing characters with values between
1342        127 and 255 was not handled correctly if the compiled pattern was studied.
1343        In fixing this, I have also improved the studying algorithm for such
1344        classes (slightly).
1346     2. Three internal functions had redundant arguments passed to them. Removal
1347        might give a very teeny performance improvement.
1349     3. Documentation bug: the value of the capture_top field in a callout is *one
1350        more than* the number of the hightest numbered captured substring.
1352     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1353        in incorrectly linking with a previously installed version. They now link
1354        explicitly with libpcre.la.
1356     5. configure.in no longer needs to recognize Cygwin specially.
1358     6. A problem in pcre.in for Windows platforms is fixed.
1360     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1361        pcretest, it used to include the size of the study block as part of its
1362        output. Unfortunately, the structure contains a field that has a different
1363        size on different hardware architectures. This meant that the tests that
1364        showed this size failed. As the block is currently always of a fixed size,
1365        this information isn't actually particularly useful in pcretest output, so
1366        I have just removed it.
1368     8. Three pre-processor statements accidentally did not start in column 1.
1369        Sadly, there are *still* compilers around that complain, even though
1370        standard C has not required this for well over a decade. Sigh.
1372     9. In pcretest, the code for checking callouts passed small integers in the
1373        callout_data field, which is a void * field. However, some picky compilers
1374        complained about the casts involved for this on 64-bit systems. Now
1375        pcretest passes the address of the small integer instead, which should get
1376        rid of the warnings.
1378    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1379        both compile and run time, and gives an error if an invalid UTF-8 sequence
1380        is found. There is a option for disabling this check in cases where the
1381        string is known to be correct and/or the maximum performance is wanted.
1383    11. In response to a bug report, I changed one line in Makefile.in from
1385            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1386        to
1387            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1389        to look similar to other lines, but I have no way of telling whether this
1390        is the right thing to do, as I do not use Windows. No doubt I'll get told
1391        if it's wrong...
1394    Version 4.3 21-May-03
1395    ---------------------
1397    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1398       Makefile.
1400    2. Some refactoring to improve the quality of the code:
1402       (i)   The utf8_table... variables are now declared "const".
1404       (ii)  The code for \cx, which used the "case flipping" table to upper case
1405             lower case letters, now just substracts 32. This is ASCII-specific,
1406             but the whole concept of \cx is ASCII-specific, so it seems
1407             reasonable.
1409       (iii) PCRE was using its character types table to recognize decimal and
1410             hexadecimal digits in the pattern. This is silly, because it handles
1411             only 0-9, a-f, and A-F, but the character types table is locale-
1412             specific, which means strange things might happen. A private
1413             table is now used for this - though it costs 256 bytes, a table is
1414             much faster than multiple explicit tests. Of course, the standard
1415             character types table is still used for matching digits in subject
1416             strings against \d.
1418       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1419             ending in _t are). So I've renamed it as ESC_tee.
1421    3. The first argument for regexec() in the POSIX wrapper should have been
1422       defined as "const".
1424    4. Changed pcretest to use malloc() for its buffers so that they can be
1425       Electric Fenced for debugging.
1427    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1428       to read one or more bytes before the start of the subject string. Often this
1429       had no effect on PCRE's behaviour, but in some circumstances it could
1430       provoke a segmentation fault.
1432    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1433       to try to read one or more bytes before the start of the subject string.
1435    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1436       UTF-8 support could misbehave in various ways if the subject string
1437       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1438       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1439       back over UTF-8 characters.)
1442    Version 4.2 14-Apr-03
1443    ---------------------
1445    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1447    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1448         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1449         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1450         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1451         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1452           and BUILD_EXEEXT
1453         Note: automatic setting of the BUILD variables is not yet working
1454         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1455           compile-time but not at link-time
1456         [LINK]: use for linking executables only
1457         make different versions for Windows and non-Windows
1458         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1459           libraries
1460         [LINK_FOR_BUILD]: new variable
1461         [OBJEXT]: use throughout
1462         [EXEEXT]: use throughout
1463         <winshared>: new target
1464         <wininstall>: new target
1465         <dftables.o>: use native compiler
1466         <dftables>: use native linker
1467         <install>: handle Windows platform correctly
1468         <clean>: ditto
1469         <check>: ditto
1470         copy DLL to top builddir before testing
1472       As part of these changes, -no-undefined was removed again. This was reported
1473       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1474       in any case.
1476    3. Some tidies to get rid of compiler warnings:
1478       . In the match_data structure, match_limit was an unsigned long int, whereas
1479         match_call_count was an int. I've made them both unsigned long ints.
1481       . In pcretest the fact that a const uschar * doesn't automatically cast to
1482         a void * provoked a warning.
1484       . Turning on some more compiler warnings threw up some "shadow" variables
1485         and a few more missing casts.
1487    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1488       option, a class that contained a single character with a value between 128
1489       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1491    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1492       option, a class that contained several characters, but with at least one
1493       whose value was between 128 and 255 caused PCRE to crash.
1496    Version 4.1 12-Mar-03
1497    ---------------------
1499    1. Compiling with gcc -pedantic found a couple of places where casts were
1500    needed, and a string in dftables.c that was longer than standard compilers are
1501    required to support.
1503    2. Compiling with Sun's compiler found a few more places where the code could
1504    be tidied up in order to avoid warnings.
1506    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1507    first of these names is deprecated in the latest Autoconf in favour of the name
1508    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1509    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1510    analogy I have changed it to CFLAGS_FOR_BUILD.
1512    4. Added -no-undefined to the linking command in the Makefile, because this is
1513    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1514    linking step for the pcreposix library.
1516    5. PCRE was failing to diagnose the case of two named groups with the same
1517    name.
1519    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1520    literal character that is needed in the subject for a match, and scans along to
1521    ensure that it is present before embarking on the full matching process. This
1522    saves time in cases of nested unlimited repeats that are never going to match.
1523    Problem: the scan can take a lot of time if the subject is very long (e.g.
1524    megabytes), thus penalizing straightforward matches. It is now done only if the
1525    amount of subject to be scanned is less than 1000 bytes.
1527    7. A lesser problem with the same optimization is that it was recording the
1528    first character of an anchored pattern as "needed", thus provoking a search
1529    right along the subject, even when the first match of the pattern was going to
1530    fail. The "needed" character is now not set for anchored patterns, unless it
1531    follows something in the pattern that is of non-fixed length. Thus, it still
1532    fulfils its original purpose of finding quick non-matches in cases of nested
1533    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1536    Version 4.0 17-Feb-03
1537    ---------------------
1539    1. If a comment in an extended regex that started immediately after a meta-item
1540    extended to the end of string, PCRE compiled incorrect data. This could lead to
1541    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1543    2. Moved to autoconf 2.53 and libtool 1.4.2.
1545    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1546    the special perltest8 script is no longer needed - all the tests can be run
1547    from a single perltest script.
1549    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1550    by \s. It has now been removed in PCRE. This means it isn't recognized as
1551    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1552    class [:space:] *does* include VT, thereby creating a mess.
1554    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1555    space and tab.
1557    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1558    its new features into the main test script, reducing the number of scripts.
1560    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1561    were backward compatible, and made the (?i) apply to the whole pattern, as if
1562    /i were given. Now it behaves more logically, and applies the option setting
1563    only to what follows. PCRE has been changed to follow suit. However, if it
1564    finds options settings right at the start of the pattern, it extracts them into
1565    the global options, as before. Thus, they show up in the info data.
1567    8. Added support for the \Q...\E escape sequence. Characters in between are
1568    treated as literals. This is slightly different from Perl in that $ and @ are
1569    also handled as literals inside the quotes. In Perl, they will cause variable
1570    interpolation. Note the following examples:
1572        Pattern            PCRE matches      Perl matches
1574        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1575        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1576        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1578    For compatibility with Perl, \Q...\E sequences are recognized inside character
1579    classes as well as outside them.
1581    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1582    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1583    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1584    signed/unsigned warnings.
1586    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1587    option for pcretest, so I've replaced it by a simple function that does just
1588    that job.
1590    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1591    "pcregrep -".
1593    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1594    Java package. This provides some syntactic sugar for simple cases of what my
1595    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1596    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1597    item, you can use this simplified notation. Note that only makes sense with
1598    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1599    greediness, whatever the setting of the PCRE_UNGREEDY option.
1601    13. A change of greediness default within a pattern was not taking effect at
1602    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1603    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1604    was abstracted outside.
1606    14. PCRE now supports the \G assertion. It is true when the current matching
1607    position is at the start point of the match. This differs from \A when the
1608    starting offset is non-zero. Used with the /g option of pcretest (or similar
1609    code), it works in the same way as it does for Perl's /g option. If all
1610    alternatives of a regex begin with \G, the expression is anchored to the start
1611    match position, and the "anchored" flag is set in the compiled expression.
1613    15. Some bugs concerning the handling of certain option changes within patterns
1614    have been fixed. These applied to options other than (?ims). For example,
1615    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1616    been the other way round. Some of this was related to change 7 above.
1618    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1619    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1620    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1621    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1623    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1624    mode. Unlike ".", it always matches newline, whatever the setting of
1625    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1626    assertions. Perl allows it, but it doesn't (in general) work because it can't
1627    calculate the length of the lookbehind. At least, that's the case for Perl
1628    5.8.0 - I've been told they are going to document that it doesn't work in
1629    future.
1631    18. Added an error diagnosis for escapes that PCRE does not support: these are
1632    \L, \l, \N, \P, \p, \U, \u, and \X.
1634    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1635    reading past the end of the pattern in cases such as /[abcd/.
1637    20. PCRE was getting more memory than necessary for patterns with classes that
1638    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1640    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1641    compiling PCRE for use with Virtual Pascal.
1643    22. Small fix to the Makefile to make it work properly if the build is done
1644    outside the source tree.
1646    23. Added a new extension: a condition to go with recursion. If a conditional
1647    subpattern starts with (?(R) the "true" branch is used if recursion has
1648    happened, whereas the "false" branch is used only at the top level.
1650    24. When there was a very long string of literal characters (over 255 bytes
1651    without UTF support, over 250 bytes with UTF support), the computation of how
1652    much memory was required could be incorrect, leading to segfaults or other
1653    strange effects.
1655    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1656    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1657    there was a subsequent back reference to those brackets. This meant that, for
1658    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1659    possible to check for precisely this case. All we can do is abandon the
1660    optimization if .* occurs inside capturing brackets when there are any back
1661    references whatsoever. (See below for a better fix that came later.)
1663    26. The handling of the optimization for finding the first character of a
1664    non-anchored pattern, and for finding a character that is required later in the
1665    match were failing in some cases. This didn't break the matching; it just
1666    failed to optimize when it could. The way this is done has been re-implemented.
1668    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1670    28. Added a new feature that provides some of the functionality that Perl
1671    provides with (?{...}). The facility is termed a "callout". The way it is done
1672    in PCRE is for the caller to provide an optional function, by setting
1673    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1674    global variable. By default it is unset, which disables all calling out. To get
1675    the function called, the regex must include (?C) at appropriate points. This
1676    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1677    This provides a means of identifying different callout points. When PCRE
1678    reaches such a point in the regex, if pcre_callout has been set, the external
1679    function is called. It is provided with data in a structure called
1680    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1681    matching continues; if it returns a non-zero value, the match at the current
1682    point fails. However, backtracking will occur if possible. [This was changed
1683    later and other features added - see item 49 below.]
1685    29. pcretest is upgraded to test the callout functionality. It provides a
1686    callout function that displays information. By default, it shows the start of
1687    the match and the current position in the text. There are some new data escapes
1688    to vary what happens:
1690        \C+         in addition, show current contents of captured substrings
1691        \C-         do not supply a callout function
1692        \C!n        return 1 when callout number n is reached
1693        \C!n!m      return 1 when callout number n is reached for the mth time
1695    30. If pcregrep was called with the -l option and just a single file name, it
1696    output "<stdin>" if a match was found, instead of the file name.
1698    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1699    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1700    pcre_exec(). This saves a malloc/free per call. The default value of
1701    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1702    when configuring.
1704    32. The default maximum size of a compiled pattern is 64K. There have been a
1705    few cases of people hitting this limit. The code now uses macros to handle the
1706    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1707    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1708    configuring. Tests 2 and 5 work only with 2-byte links because they output
1709    debugging information about compiled patterns.
1711    33. Internal code re-arrangements:
1713    (a) Moved the debugging function for printing out a compiled regex into
1714        its own source file (printint.c) and used #include to pull it into
1715        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1716        separate copies.
1718    (b) Defined the list of op-code names for debugging as a macro in
1719        internal.h so that it is next to the definition of the opcodes.
1721    (c) Defined a table of op-code lengths for simpler skipping along compiled
1722        code. This is again a macro in internal.h so that it is next to the
1723        definition of the opcodes.
1725    34. Added support for recursive calls to individual subpatterns, along the
1726    lines of Robin Houston's patch (but implemented somewhat differently).
1728    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1729    allow it to read and process whole directories in Win32. This code was
1730    contributed by Lionel Fourquaux; it has not been tested by me.
1732    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1733    used to name a group. Names consist of alphanumerics and underscores, and must
1734    be unique. Back references use the syntax (?P=name) and recursive calls use
1735    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1736    numbers. The function pcre_fullinfo() can be used after compilation to extract
1737    a name/number map. There are three relevant calls:
1739      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1740      PCRE_INFO_NAMECOUNT            yields the number of entries
1741      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1743    The map is a vector of fixed-size entries. The size of each entry depends on
1744    the length of the longest name used. The first two bytes of each entry are the
1745    group number, most significant byte first. There follows the corresponding
1746    name, zero terminated. The names are in alphabetical order.
1748    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1749    case instead of 255. Making it the same both with and without UTF-8 support
1750    means that the same test output works with both.
1752    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1753    calling malloc() with a zero argument.
1755    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1756    optimization. I've improved things by keeping a bitmap of backreferences with
1757    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1758    fact referenced, the optimization can be applied. It is unlikely that a
1759    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1760    the match to follow \n) will appear inside brackets with a number greater than
1761    31, but if it does, any back reference > 31 suppresses the optimization.
1763    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1764    of disabling numbered capturing parentheses. Any opening parenthesis that is
1765    not followed by ? behaves as if it were followed by ?: but named parentheses
1766    can still be used for capturing (and they will acquire numbers in the usual
1767    way).
1769    41. Redesigned the return codes from the match() function into yes/no/error so
1770    that errors can be passed back from deep inside the nested calls. A malloc
1771    failure while inside a recursive subpattern call now causes the
1772    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1774    42. It is now possible to set a limit on the number of times the match()
1775    function is called in a call to pcre_exec(). This facility makes it possible to
1776    limit the amount of recursion and backtracking, though not in a directly
1777    obvious way, because the match() function is used in a number of different
1778    circumstances. The count starts from zero for each position in the subject
1779    string (for non-anchored patterns). The default limit is, for compatibility, a
1780    large number, namely 10 000 000. You can change this in two ways:
1782    (a) When configuring PCRE before making, you can use --with-match-limit=n
1783        to set a default value for the compiled library.
1785    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1786        a different value is set. See 45 below.
1788    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1790    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1791    of things that can be changed at compile time. The first argument specifies
1792    what is wanted and the second points to where the information is to be placed.
1793    The current list of available information is:
1795      PCRE_CONFIG_UTF8
1797    The output is an integer that is set to one if UTF-8 support is available;
1798    otherwise it is set to zero.
1802    The output is an integer that it set to the value of the code that is used for
1803    newline. It is either LF (10) or CR (13).
1807    The output is an integer that contains the number of bytes used for internal
1808    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1812    The output is an integer that contains the threshold above which the POSIX
1813    interface uses malloc() for output vectors. See item 31 above.
1817    The output is an unsigned integer that contains the default limit of the number
1818    of match() calls in a pcre_exec() execution. See 42 above.
1820    44. pcretest has been upgraded by the addition of the -C option. This causes it
1821    to extract all the available output from the new pcre_config() function, and to
1822    output it. The program then exits immediately.
1824    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1825    order to support additional features. One way would have been to define
1826    pcre_exec2() (for example) with extra arguments, but this would not have been
1827    extensible, and would also have required all calls to the original function to
1828    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1829    is used for passing in "extra" data from pcre_study().
1831    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1832    contains the following fields:
1834      flags         a bitmap indicating which of the following fields are set
1835      study_data    opaque data from pcre_study()
1836      match_limit   a way of specifying a limit on match() calls for a specific
1837                      call to pcre_exec()
1838      callout_data  data for callouts (see 49 below)
1840    The flag bits are also defined in pcre.h, and are
1846    The pcre_study() function now returns one of these new pcre_extra blocks, with
1847    the actual study data pointed to by the study_data field, and the
1848    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1849    before. That is, this change is entirely upwards-compatible and requires no
1850    change to existing code.
1852    If you want to pass in additional data to pcre_exec(), you can either place it
1853    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1854    block.
1856    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1857    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1858    times with different match limits, until it finds the minimum value needed for
1859    pcre_exec() to complete. The value is then output. This can be instructive; for
1860    most simple matches the number is quite small, but for pathological cases it
1861    gets very large very quickly.
1863    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1864    returns the size of the data block pointed to by the study_data field in a
1865    pcre_extra block, that is, the value that was passed as the argument to
1866    pcre_malloc() when PCRE was getting memory in which to place the information
1867    created by pcre_study(). The fourth argument should point to a size_t variable.
1868    pcretest has been extended so that this information is shown after a successful
1869    pcre_study() call when information about the compiled regex is being displayed.
1871    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1872    because what follows is always an absolute path. (Later: it turns out that this
1873    is more than cosmetic for MinGW, because it doesn't like empty path
1874    components.)
1876    49. Some changes have been made to the callout feature (see 28 above):
1878    (i)  A callout function now has three choices for what it returns:
1880           0  =>  success, carry on matching
1881         > 0  =>  failure at this point, but backtrack if possible
1882         < 0  =>  serious error, return this value from pcre_exec()
1884         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1885         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1886         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1887         use by callout functions. It will never be used by PCRE itself.
1889    (ii) The pcre_extra structure (see 45 above) has a void * field called
1890         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1891         pcre_callout_block structure has a field of the same name. The contents of
1892         the field passed in the pcre_extra structure are passed to the callout
1893         function in the corresponding field in the callout block. This makes it
1894         easier to use the same callout-containing regex from multiple threads. For
1895         testing, the pcretest program has a new data escape
1897           \C*n        pass the number n (may be negative) as callout_data
1899         If the callout function in pcretest receives a non-zero value as
1900         callout_data, it returns that value.
1902    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1903    there were some redundant $(CFLAGS) in commands that are now specified as
1904    $(LINK), which already includes $(CFLAGS).
1906    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1907    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1908    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1909    one-byte characters throughout. Note that case-insensitive matching applies
1910    only to characters whose values are less than 256. PCRE doesn't support the
1911    notion of cases for higher-valued characters.
1913    (i)   A character class whose characters are all within 0-255 is handled as
1914          a bit map, and the map is inverted for negative classes. Previously, a
1915          character > 255 always failed to match such a class; however it should
1916          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1918    (ii)  A negated character class with a single character < 255 is coded as
1919          "not this character" (OP_NOT). This wasn't working properly when the test
1920          character was multibyte, either singly or repeated.
1922    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1923          mode, for example: \x{100}{2,3}.
1925    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1926          singly or repeated) now correctly test multibyte characters. However,
1927          PCRE doesn't recognize any characters with values greater than 255 as
1928          digits, spaces, or word characters. Such characters always match \D, \S,
1929          and \W, and never match \d, \s, or \w.
1931    (v)   Classes may now contain characters and character ranges with values
1932          greater than 255. For example: [ab\x{100}-\x{400}].
1934    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1935          PCRE in UTF-8 mode.
1937    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1938    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1939    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1940    value.)
1942    53. The single man page has become too large. I have therefore split it up into
1943    a number of separate man pages. These also give rise to individual HTML pages;
1944    these are now put in a separate directory, and there is an index.html page that
1945    lists them all. Some hyperlinking between the pages has been installed.
1947    54. Added convenience functions for handling named capturing parentheses.
1949    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1950    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1951    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1952    are faulted.
1954    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1955    calling configure. These values are used when compiling the dftables.c program
1956    which is run to generate the source of the default character tables. They
1957    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1958    you will need to set these values.
1960    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1963    Version 3.9 02-Jan-02
1964    ---------------------
1966    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1968    2. If --disable-static was given, the building process failed when trying to
1969    build pcretest and pcregrep. (For some reason it was using libtool to compile
1970    them, which is not right, as they aren't part of the library.)
1973    Version 3.8 18-Dec-01
1974    ---------------------
1976    1. The experimental UTF-8 code was completely screwed up. It was packing the
1977    bytes in the wrong order. How dumb can you get?
1980    Version 3.7 29-Oct-01
1981    ---------------------
1983    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1984    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1985    this didn't happen under Solaris 8, where I normally test things.
1987    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1988    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1989    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1990    this fix an hour or so after the initial 3.7 release.)
1993    Version 3.6 23-Oct-01
1994    ---------------------
1996    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1997    offsets passed as NULL with zero offset count.
1999    2. The config.guess and config.sub files had not been updated when I moved to
2000    the latest autoconf.
2003    Version 3.5 15-Aug-01
2004    ---------------------
2006    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2007    had been forgotten.
2009    2. By using declared but undefined structures, we can avoid using "void"
2010    definitions in pcre.h while keeping the internal definitions of the structures
2011    private.
2013    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2014    user point of view, this means that both static and shared libraries are built
2015    by default, but this can be individually controlled. More of the work of
2016    handling this static/shared cases is now inside libtool instead of PCRE's make
2017    file.
2019    4. The pcretest utility is now installed along with pcregrep because it is
2020    useful for users (to test regexs) and by doing this, it automatically gets
2021    relinked by libtool. The documentation has been turned into a man page, so
2022    there are now .1, .txt, and .html versions in /doc.
2024    5. Upgrades to pcregrep:
2025       (i)   Added long-form option names like gnu grep.
2026       (ii)  Added --help to list all options with an explanatory phrase.
2027       (iii) Added -r, --recursive to recurse into sub-directories.
2028       (iv)  Added -f, --file to read patterns from a file.
2030    6. pcre_exec() was referring to its "code" argument before testing that
2031    argument for NULL (and giving an error if it was NULL).
2033    7. Upgraded Makefile.in to allow for compiling in a different directory from
2034    the source directory.
2036    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2037    options bits, the pointer it was passed was to an int instead of to an unsigned
2038    long int. This mattered only on 64-bit systems.
2040    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2041    generated) instead of pcre.in, which it its source. Also made the same change
2042    in several of the .c files.
2044    10. A new release of gcc defines printf() as a macro, which broke pcretest
2045    because it had an ifdef in the middle of a string argument for printf(). Fixed
2046    by using separate calls to printf().
2048    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2049    script, to force use of CR or LF instead of \n in the source. On non-Unix
2050    systems, the value can be set in config.h.
2052    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2053    absolute limit. Changed the text of the error message to make this clear, and
2054    likewise updated the man page.
2056    13. The limit of 99 on the number of capturing subpatterns has been removed.
2057    The new limit is 65535, which I hope will not be a "real" limit.
2060    Version 3.4 22-Aug-00
2061    ---------------------
2063    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2065    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2068    Version 3.3 01-Aug-00
2069    ---------------------
2071    1. If an octal character was given, but the value was greater than \377, it
2072    was not getting masked to the least significant bits, as documented. This could
2073    lead to crashes in some systems.
2075    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2076    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2078    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2079    These just pass their arguments on to (pcre_free)(), but they are provided
2080    because some uses of PCRE bind it to non-C systems that can call its functions,
2081    but cannot call free() or pcre_free() directly.
2083    4. Add "make test" as a synonym for "make check". Corrected some comments in
2084    the Makefile.
2086    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2087    Makefile.
2089    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2090    command called pgrep for grepping around the active processes.
2092    7. Added the beginnings of support for UTF-8 character strings.
2094    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2095    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2096    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2097    out for the ar command.)
2100    Version 3.2 12-May-00
2101    ---------------------
2103    This is purely a bug fixing release.
2105    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2106    of ZA. This was just one example of several cases that could provoke this bug,
2107    which was introduced by change 9 of version 2.00. The code for breaking
2108    infinite loops after an iteration that matches an empty string was't working
2109    correctly.
2111    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2112    when matched against abbab (for example). After matching an empty string, it
2113    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2114    caused it to match further down the string than it should.
2116    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2117    was there because it doesn't seem to be needed, and it causes trouble on some
2118    systems, as it is not a Standard C header. It has been removed.
2120    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2121    were reported on the Macintosh. The changes were from
2123      while ((c = *(++ptr)) != 0 && c != '\n');
2124    to
2125      while ((c = *(++ptr)) != 0 && c != '\n') ;
2127    Totally extraordinary, but if that's what it takes...
2129    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2130    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2131    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2132    assumes the way PCRE uses memmove() (always moving upwards).
2134    6. PCRE is being used in one environment where strchr() is not available. There
2135    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2136    faster code anyway.
2139    Version 3.1 09-Feb-00
2140    ---------------------
2142    The only change in this release is the fixing of some bugs in Makefile.in for
2143    the "install" target:
2145    (1) It was failing to install pcreposix.h.
2147    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2150    Version 3.0 01-Feb-00
2151    ---------------------
2153    1. Add support for the /+ modifier to perltest (to output $` like it does in
2154    pcretest).
2156    2. Add support for the /g modifier to perltest.
2158    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2159    matches null strings.
2161    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2162    pattern. Perl treats empty patterns specially - it reuses the most recent
2163    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2164    effect.
2166    5. The POSIX interface was broken in that it was just handing over the POSIX
2167    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2168    required a bigger vector, with some working space on the end. This means that
2169    the POSIX wrapper now has to get and free some memory, and copy the results.
2171    6. Added some simple autoconf support, placing the test data and the
2172    documentation in separate directories, re-organizing some of the
2173    information files, and making it build pcre-config (a GNU standard). Also added
2174    libtool support for building PCRE as a shared library, which is now the
2175    default.
2177    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2178    09 are not valid octal constants. Single digits will be used for minor values
2179    less than 10.
2181    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2182    existing programs that set these in the POSIX interface can use PCRE without
2183    modification.
2185    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2186    return all that pcre_info() returns, plus additional data. The pcre_info()
2187    function is retained for compatibility, but is considered to be obsolete.
2189    10. Added experimental recursion feature (?R) to handle one common case that
2190    Perl 5.6 will be able to do with (?p{...}).
2192    11. Added support for POSIX character classes like [:alpha:], which Perl is
2193    adopting.
2196    Version 2.08 31-Aug-99
2197    ----------------------
2199    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2200    trying to match at the startoffset position, but instead was moving forward to
2201    the next newline as if a previous match had failed.
2203    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2204    and could get into a loop if a null string was matched other than at the start
2205    of the subject.
2207    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2208    be distinguished at compile time, and for completeness also added PCRE_DATE.
2210    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2211    in GnuWin32 environments.
2214    Version 2.07 29-Jul-99
2215    ----------------------
2217    1. The documentation is now supplied in plain text form and HTML as well as in
2218    the form of man page sources.
2220    2. C++ compilers don't like assigning (void *) values to other pointer types.
2221    In particular this affects malloc(). Although there is no problem in Standard
2222    C, I've put in casts to keep C++ compilers happy.
2224    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2225    should be (const char *).
2227    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2228    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2229    However, I haven't made this a standard facility. The documentation doesn't
2230    mention it, and the Makefile doesn't support it.
2232    5. The Makefile now contains an "install" target, with editable destinations at
2233    the top of the file. The pcretest program is not installed.
2235    6. pgrep -V now gives the PCRE version number and date.
2237    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2238    causing the entire string to be ignored, instead of just the last character.
2240    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2241    non-matching string, it can take a very, very long time, even for strings of
2242    quite modest length, because of the nested recursion. PCRE now does better in
2243    some of these cases. It does this by remembering the last required literal
2244    character in the pattern, and pre-searching the subject to ensure it is present
2245    before running the real match. In other words, it applies a heuristic to detect
2246    some types of certain failure quickly, and in the above example, if presented
2247    with a string that has no trailing " it gives "no match" very quickly.
2249    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2250    other alternatives are tried instead.
2253    Version 2.06 09-Jun-99
2254    ----------------------
2256    1. Change pcretest's output for amount of store used to show just the code
2257    space, because the remainder (the data block) varies in size between 32-bit and
2258    64-bit systems.
2260    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2261    start matching at. This allows lookbehinds to work when searching for multiple
2262    occurrences in a string.
2264    3. Added additional options to pcretest for testing multiple occurrences:
2266       /+   outputs the rest of the string that follows a match
2267       /g   loops for multiple occurrences, using the new startoffset argument
2268       /G   loops for multiple occurrences by passing an incremented pointer
2270    4. PCRE wasn't doing the "first character" optimization for patterns starting
2271    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2272    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2273    the letter 'x'. On long subject strings, this gives a significant speed-up.
2276    Version 2.05 21-Apr-99
2277    ----------------------
2279    1. Changed the type of magic_number from int to long int so that it works
2280    properly on 16-bit systems.
2282    2. Fixed a bug which caused patterns starting with .* not to work correctly
2283    when the subject string contained newline characters. PCRE was assuming
2284    anchoring for such patterns in all cases, which is not correct because .* will
2285    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2286    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2287    must be retried after every newline in the subject.
2290    Version 2.04 18-Feb-99
2291    ----------------------
2293    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2294    computation of the store needed to hold the pattern was incorrect (too large).
2295    If such patterns were nested a few deep, this could multiply and become a real
2296    problem.
2298    2. Added /M option to pcretest to show the memory requirement of a specific
2299    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2301    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2302    compiled in such a way that the backtracking after subsequent failure was
2303    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2304    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2307    Version 2.03 02-Feb-99
2308    ----------------------
2310    1. Fixed typo and small mistake in man page.
2312    2. Added 4th condition (GPL supersedes if conflict) and created separate
2313    LICENCE file containing the conditions.
2315    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2316    Perl, that is the internal \ allows the delimiter to be included in the
2317    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2318    the final delimiter, add \ to the end of the pattern (to test the error).
2320    4. Added the convenience functions for extracting substrings after a successful
2321    match. Updated pcretest to make it able to test these functions.
2324  Version 2.02 14-Jan-99  Version 2.02 14-Jan-99
2325  ----------------------  ----------------------

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