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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 8.21
5    ------------
7    1.  Updating the JIT compiler.
9    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10        are added as well.
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14        calling _pcre_jit_exec. Some extra comments are added.
16    4.  Mark settings inside atomic groups that do not contain any capturing
17        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18        was introduced by change 18 for 8.20.
20    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
23    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25        This bug was probably introduced by change 9 of 8.13.
27    7.  While fixing 6 above, I noticed that a number of other items were being
28        incorrectly rejected as "not fixed length". This arose partly because newer
29        opcodes had not been added to the fixed-length checking code. I have (a)
30        corrected the bug and added tests for these items, and (b) arranged for an
31        error to occur if an unknown opcode is encountered while checking for fixed
32        length instead of just assuming "not fixed length". The items that were
33        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
37    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38        being incorrectly compiled and would have given unpredicatble results.
40    9.  A possessively repeated subpattern with minimum repeat count greater than
41        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43        the first (A) could occur when it should not.
45    10. Add a cast and remove a redundant test from the code.
47    11. JIT should use pcre_malloc/pcre_free for allocation.
49    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
50        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
51        is anything other than /usr, -L is still shown).
53    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
55    14. Perl does not support \N without a following name in a [] class; PCRE now
56        also gives an error.
58    15. If a forward reference was repeated with an upper limit of around 2000,
59        it caused the error "internal error: overran compiling workspace". The
60        maximum number of forward references (including repeats) was limited by the
61        internal workspace, and dependent on the LINK_SIZE. The code has been
62        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
63        the default depends on LINK_SIZE. There is a new upper limit (for safety)
64        of around 200,000 forward references. While doing this, I also speeded up
65        the filling in of repeated forward references.
67    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
68        incorrectly expecting the subject to contain another "a" after the start.
70    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
71        in the match, the SKIP should be ignored. This was not happening; instead
72        the SKIP was being treated as NOMATCH. For patterns such as
73        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
74        tested.
76    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
77        now much more compatible with Perl, in particular in cases where the result
78        is a non-match for a non-anchored pattern. For example, if
79        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
80        "m", where previously it did not return a name. A side effect of this
81        change is that for partial matches, the last encountered mark name is
82        returned, as for non matches. A number of tests that were previously not
83        Perl-compatible have been moved into the Perl-compatible test files. The
84        refactoring has had the pleasing side effect of removing one argument from
85        the match() function, thus reducing its stack requirements.
87    19. If the /S+ option was used in pcretest to study a pattern using JIT,
88        subsequent uses of /S (without +) incorrectly behaved like /S+.
90    21. Retrieve executable code size support for the JIT compiler and fixing
91        some warnings.
93    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
94        not work when the shorter character appeared right at the end of the
95        subject string.
97    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
98        systems.
101    Version 8.20 21-Oct-2011
102    ------------------------
104    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
105        a POSIX class. After further experiments with Perl, which convinced me that
106        Perl has bugs and confusions, a closing square bracket is no longer allowed
107        in a POSIX name. This bug also affected patterns with classes that started
108        with full stops.
110    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
111        captured substring, but while checking the failing first alternative,
112        substring 1 is temporarily captured. If the output vector supplied to
113        pcre_exec() was not big enough for this capture, the yield of the function
114        was still zero ("insufficient space for captured substrings"). This cannot
115        be totally fixed without adding another stack variable, which seems a lot
116        of expense for a edge case. However, I have improved the situation in cases
117        such as /(a)(b)x|abc/ matched against "abc", where the return code
118        indicates that fewer than the maximum number of slots in the ovector have
119        been set.
121    3.  Related to (2) above: when there are more back references in a pattern than
122        slots in the output vector, pcre_exec() uses temporary memory during
123        matching, and copies in the captures as far as possible afterwards. It was
124        using the entire output vector, but this conflicts with the specification
125        that only 2/3 is used for passing back captured substrings. Now it uses
126        only the first 2/3, for compatibility. This is, of course, another edge
127        case.
129    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
130        main code base, and can be used by building with --enable-jit. When this is
131        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
132        runtime --no-jit option is given.
134    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
135        ovector, the return from the function was zero, implying that there were
136        other matches that did not fit. The correct "exactly full" value is now
137        returned.
139    6.  If a subpattern that was called recursively or as a subroutine contained
140        (*PRUNE) or any other control that caused it to give a non-standard return,
141        invalid errors such as "Error -26 (nested recursion at the same subject
142        position)" or even infinite loops could occur.
144    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
145        computing the minimum length on reaching *ACCEPT, and so ended up with the
146        wrong value of 1 rather than 0. Further investigation indicates that
147        computing a minimum subject length in the presence of *ACCEPT is difficult
148        (think back references, subroutine calls), and so I have changed the code
149        so that no minimum is registered for a pattern that contains *ACCEPT.
151    8.  If (*THEN) was present in the first (true) branch of a conditional group,
152        it was not handled as intended. [But see 16 below.]
154    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
155        Sheri Pierce.
157    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
158        the first byte in a match must be "a".
160    11. Change 17 for 8.13 increased the recursion depth for patterns like
161        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
162        pattern contains any instances of (*THEN). If it does not, the old
163        optimizations are restored. It would be nice to do this on a per-group
164        basis, but at the moment that is not feasible.
166    12. In some environments, the output of pcretest -C is CRLF terminated. This
167        broke RunTest's code that checks for the link size. A single white space
168        character after the value is now allowed for.
170    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
171        For "fr", it uses the Windows-specific input and output files.
173    14. If (*THEN) appeared in a group that was called recursively or as a
174        subroutine, it did not work as intended. [But see next item.]
176    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
177        pattern fragments (but not containing any | characters). If A and B are
178        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
179        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
180        D. In other words, Perl considers parentheses that do not contain any |
181        characters to be part of a surrounding alternative, whereas PCRE was
182        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
183        differently. PCRE now behaves in the same way as Perl, except in the case
184        of subroutine/recursion calls such as (?1) which have in any case always
185        been different (but PCRE had them first :-).
187    16. Related to 15 above: Perl does not treat the | in a conditional group as
188        creating alternatives. Such a group is treated in the same way as an
189        ordinary group without any | characters when processing (*THEN). PCRE has
190        been changed to match Perl's behaviour.
192    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
193        RunGrepTest script failed.
195    18. Change 22 for version 13 caused atomic groups to use more stack. This is
196        inevitable for groups that contain captures, but it can lead to a lot of
197        stack use in large patterns. The old behaviour has been restored for atomic
198        groups that do not contain any capturing parentheses.
200    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
201        suppress the check for a minimum subject length at run time. (If it was
202        given to pcre_exec() or pcre_dfa_exec() it did work.)
204    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
205        fail to work when decoding hex characters in data strings in EBCDIC
206        environments.
208    21. It appears that in at least one Mac OS environment, the isxdigit() function
209        is implemented as a macro that evaluates to its argument more than once,
210        contravening the C 90 Standard (I haven't checked a later standard). There
211        was an instance in pcretest which caused it to go wrong when processing
212        \x{...} escapes in subject strings. The has been rewritten to avoid using
213        things like p++ in the argument of isxdigit().
216    Version 8.13 16-Aug-2011
217    ------------------------
219    1.  The Unicode data tables have been updated to Unicode 6.0.0.
221    2.  Two minor typos in pcre_internal.h have been fixed.
223    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
224        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
225        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
227    4.  There were a number of related bugs in the code for matching backrefences
228        caselessly in UTF-8 mode when codes for the characters concerned were
229        different numbers of bytes. For example, U+023A and U+2C65 are an upper
230        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
231        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
232        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
233        2-byte code at the end of the subject (it thought there wasn't enough data
234        left).
236    5.  Comprehensive information about what went wrong is now returned by
237        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
238        as the output vector has at least 2 elements. The offset of the start of
239        the failing character and a reason code are placed in the vector.
241    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
242        now returned is for the first byte of the failing character, instead of the
243        last byte inspected. This is an incompatible change, but I hope it is small
244        enough not to be a problem. It makes the returned offset consistent with
245        pcre_exec() and pcre_dfa_exec().
247    7.  pcretest now gives a text phrase as well as the error number when
248        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
249        failure, the offset and reason code are output.
251    8.  When \R was used with a maximizing quantifier it failed to skip backwards
252        over a \r\n pair if the subsequent match failed. Instead, it just skipped
253        back over a single character (\n). This seems wrong (because it treated the
254        two characters as a single entity when going forwards), conflicts with the
255        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
256        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
257        has been changed.
259    9.  Some internal refactoring has changed the processing so that the handling
260        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
261        time (the PCRE_DOTALL option was changed this way some time ago: version
262        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
263        which was always a bit of a fudge. It also means that there is one less
264        argument for the match() function, which reduces its stack requirements
265        slightly. This change also fixes an incompatibility with Perl: the pattern
266        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
268    10. More internal refactoring has drastically reduced the number of recursive
269        calls to match() for possessively repeated groups such as (abc)++ when
270        using pcre_exec().
272    11. While implementing 10, a number of bugs in the handling of groups were
273        discovered and fixed:
275        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
276        (a|)*(?1) gave a compile-time internal error.
277        ((a|)+)+  did not notice that the outer group could match an empty string.
278        (^a|^)+   was not marked as anchored.
279        (.*a|.*)+ was not marked as matching at start or after a newline.
281    12. Yet more internal refactoring has removed another argument from the match()
282        function. Special calls to this function are now indicated by setting a
283        value in a variable in the "match data" data block.
285    13. Be more explicit in pcre_study() instead of relying on "default" for
286        opcodes that mean there is no starting character; this means that when new
287        ones are added and accidentally left out of pcre_study(), testing should
288        pick them up.
290    14. The -s option of pcretest has been documented for ages as being an old
291        synonym of -m (show memory usage). I have changed it to mean "force study
292        for every regex", that is, assume /S for every regex. This is similar to -i
293        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
294        using it. It makes it easier to run collections of tests with and without
295        study enabled, and thereby test pcre_study() more easily. All the standard
296        tests are now run with and without -s (but some patterns can be marked as
297        "never study" - see 20 below).
299    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
300        restoration of the capturing data to the outer values was not happening
301        correctly.
303    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
304        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
305        pattern had matched an empty string, and so incorrectly returned a no
306        match.
308    17. There was optimizing code for the last branch of non-capturing parentheses,
309        and also for the obeyed branch of a conditional subexpression, which used
310        tail recursion to cut down on stack usage. Unfortunately, now that there is
311        the possibility of (*THEN) occurring in these branches, tail recursion is
312        no longer possible because the return has to be checked for (*THEN). These
313        two optimizations have therefore been removed. [But see 8.20/11 above.]
315    18. If a pattern containing \R was studied, it was assumed that \R always
316        matched two bytes, thus causing the minimum subject length to be
317        incorrectly computed because \R can also match just one byte.
319    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
320        was incorrectly computed.
322    20. If /S is present twice on a test pattern in pcretest input, it now
323        *disables* studying, thereby overriding the use of -s on the command line
324        (see 14 above). This is necessary for one or two tests to keep the output
325        identical in both cases.
327    21. When (*ACCEPT) was used in an assertion that matched an empty string and
328        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
330    22. When an atomic group that contained a capturing parenthesis was
331        successfully matched, but the branch in which it appeared failed, the
332        capturing was not being forgotten if a higher numbered group was later
333        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
334        group 1 to "a", when in fact it should be unset. This applied to multi-
335        branched capturing and non-capturing groups, repeated or not, and also to
336        positive assertions (capturing in negative assertions does not happen
337        in PCRE) and also to nested atomic groups.
339    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
340        subject after a captured substring, to make it easier to tell which of a
341        number of identical substrings has been captured.
343    24. The way atomic groups are processed by pcre_exec() has been changed so that
344        if they are repeated, backtracking one repetition now resets captured
345        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
346        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
347        "aaa". Previously, it would have been "a". As part of this code
348        refactoring, the way recursive calls are handled has also been changed.
350    25. If an assertion condition captured any substrings, they were not passed
351        back unless some other capturing happened later. For example, if
352        (?(?=(a))a) was matched against "a", no capturing was returned.
354    26. When studying a pattern that contained subroutine calls or assertions,
355        the code for finding the minimum length of a possible match was handling
356        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
357        group 1 called group 2 while simultaneously a separate group 2 called group
358        1). A stack overflow occurred in this case. I have fixed this by limiting
359        the recursion depth to 10.
361    27. Updated RunTest.bat in the distribution to the version supplied by Tom
362        Fortmann. This supports explicit test numbers on the command line, and has
363        argument validation and error reporting.
365    28. An instance of \X with an unlimited repeat could fail if at any point the
366        first character it looked at was a mark character.
368    29. Some minor code refactoring concerning Unicode properties and scripts
369        should reduce the stack requirement of match() slightly.
371    30. Added the '=' option to pcretest to check the setting of unused capturing
372        slots at the end of the pattern, which are documented as being -1, but are
373        not included in the return count.
375    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
376        compiled something random. Now it gives a compile-time error (as does
377        Perl).
379    32. A *MARK encountered during the processing of a positive assertion is now
380        recorded and passed back (compatible with Perl).
382    33. If --only-matching or --colour was set on a pcregrep call whose pattern
383        had alternative anchored branches, the search for a second match in a line
384        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
385        matched the line "0102" twice. The same bug affected patterns that started
386        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
387        twice.
389    34. Previously, PCRE did not allow quantification of assertions. However, Perl
390        does, and because of capturing effects, quantifying parenthesized
391        assertions may at times be useful. Quantifiers are now allowed for
392        parenthesized assertions.
394    35. A minor code tidy in pcre_compile() when checking options for \R usage.
396    36. \g was being checked for fancy things in a character class, when it should
397        just be a literal "g".
399    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
400        appearance of a nested POSIX class supersedes an apparent external class.
401        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
402        unescaped square brackets may also appear as part of class names. For
403        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
404        more like Perl. (But see 8.20/1 above.)
406    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
407        was because it thought it was \N{name}, which is not supported).
409    39. Add minix to OS list not supporting the -S option in pcretest.
411    40. PCRE tries to detect cases of infinite recursion at compile time, but it
412        cannot analyze patterns in sufficient detail to catch mutual recursions
413        such as ((?1))((?2)). There is now a runtime test that gives an error if a
414        subgroup is called recursively as a subpattern for a second time at the
415        same position in the subject string. In previous releases this might have
416        been caught by the recursion limit, or it might have run out of stack.
418    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
419        happen only once. PCRE was, however incorrectly giving a compile time error
420        "recursive call could loop indefinitely" because it cannot analyze the
421        pattern in sufficient detail. The compile time test no longer happens when
422        PCRE is compiling a conditional subpattern, but actual runaway loops are
423        now caught at runtime (see 40 above).
425    42. It seems that Perl allows any characters other than a closing parenthesis
426        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
427        has been changed to be the same.
429    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
430        as not to get warnings when autogen.sh is called. Also changed
431        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
433    44. To help people who use pcregrep to scan files containing exceedingly long
434        lines, the following changes have been made:
436        (a) The default value of the buffer size parameter has been increased from
437            8K to 20K. (The actual buffer used is three times this size.)
439        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
440            PCRE is built.
442        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
443            to be set at run time.
445        (d) Numerical values in pcregrep options can be followed by K or M, for
446            example --buffer-size=50K.
448        (e) If a line being scanned overflows pcregrep's buffer, an error is now
449            given and the return code is set to 2.
451    45. Add a pointer to the latest mark to the callout data block.
453    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
454        partial match of an empty string instead of no match. This was specific to
455        the use of ".".
457    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
458        complete match instead of a partial match. This bug was dependent on both
459        the PCRE_UTF8 and PCRE_DOTALL options being set.
461    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
462        starting byte set, because \b was not being ignored.
465    Version 8.12 15-Jan-2011
466    ------------------------
468    1.  Fixed some typos in the markup of the man pages, and wrote a script that
469        checks for such things as part of the documentation building process.
471    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
472        --match-limit and --recursion-limit options (added for 8.11). In
473        particular, this made one of the standard tests fail. (The integer value
474        went into the wrong half of a long int.)
476    3.  If the --colour option was given to pcregrep with -v (invert match), it
477        did strange things, either producing crazy output, or crashing. It should,
478        of course, ignore a request for colour when reporting lines that do not
479        match.
481    4.  Another pcregrep bug caused similar problems if --colour was specified with
482        -M (multiline) and the pattern match finished with a line ending.
484    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
485        matched in multiline mode, the following line was shown as part of the
486        match. This seems wrong, so I have changed it.
488    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
489        the check for further matches in the same line (so they could be coloured)
490        to overrun the end of the current line. If another match was found, it was
491        incorrectly shown (and then shown again when found in the next line).
493    7.  If pcregrep was compiled under Windows, there was a reference to the
494        function pcregrep_exit() before it was defined. I am assuming this was
495        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
496        reported by a user. I've moved the definition above the reference.
499    Version 8.11 10-Dec-2010
500    ------------------------
502    1.  (*THEN) was not working properly if there were untried alternatives prior
503        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
504        backtracked to try for "b" instead of moving to the next alternative branch
505        at the same level (in this case, to look for "c"). The Perl documentation
506        is clear that when (*THEN) is backtracked onto, it goes to the "next
507        alternative in the innermost enclosing group".
509    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
510        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
511        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
512        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
513        (*THEN).
515    3.  If \s appeared in a character class, it removed the VT character from
516        the class, even if it had been included by some previous item, for example
517        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
518        of \s, but is part of the POSIX "space" class.)
520    4.  A partial match never returns an empty string (because you can always
521        match an empty string at the end of the subject); however the checking for
522        an empty string was starting at the "start of match" point. This has been
523        changed to the "earliest inspected character" point, because the returned
524        data for a partial match starts at this character. This means that, for
525        example, /(?<=abc)def/ gives a partial match for the subject "abc"
526        (previously it gave "no match").
528    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
529        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
530        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
531        has an implication that the given string is incomplete (because a partial
532        match is preferred over a full match). For this reason, these items now
533        give a partial match in this situation. [Aside: previously, the one case
534        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
535        match rather than a full match, which was wrong by the old rules, but is
536        now correct.]
538    6.  There was a bug in the handling of #-introduced comments, recognized when
539        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
540        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
541        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
542        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
543        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
544        places in pcre_compile().
546    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
547        comments when looking ahead for named forward references to subpatterns,
548        the only newline sequence it recognized was NL. It now handles newlines
549        according to the set newline convention.
551    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
552        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
553        cater for a lack of strerror(). These oversights have been fixed.
555    9.  Added --match-limit and --recursion-limit to pcregrep.
557    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
559    11. When the -o option was used, pcregrep was setting a return code of 1, even
560        when matches were found, and --line-buffered was not being honoured.
562    12. Added an optional parentheses number to the -o and --only-matching options
563        of pcregrep.
565    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
566        can match an empty string. The code to do it in pcretest and pcredemo
567        needed fixing:
569        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
570            only one byte after an empty string match just before CRLF (this case
571            just got forgotten; "any" and "anycrlf" were OK).
573        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
574            mode when an empty string match preceded an ASCII character followed by
575            a non-ASCII character. (The code for advancing by one character rather
576            than one byte was nonsense.)
578        (c) The pcredemo.c sample program did not have any code at all to handle
579            the cases when CRLF is a valid newline sequence.
581    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
582        as a starting offset was within the subject string. There is now a new
583        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
584        negative or greater than the length of the string. In order to test this,
585        pcretest is extended to allow the setting of negative starting offsets.
587    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
588        starting offset points to the beginning of a UTF-8 character was
589        unnecessarily clumsy. I tidied it up.
591    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
592        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
594    17. Nobody had reported that the --include_dir option, which was added in
595        release 7.7 should have been called --include-dir (hyphen, not underscore)
596        for compatibility with GNU grep. I have changed it to --include-dir, but
597        left --include_dir as an undocumented synonym, and the same for
598        --exclude-dir, though that is not available in GNU grep, at least as of
599        release 2.5.4.
601    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
602        characters from a string of bytes) have been redefined so as not to use
603        loops, in order to improve performance in some environments. At the same
604        time, I abstracted some of the common code into auxiliary macros to save
605        repetition (this should not affect the compiled code).
607    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
608        compile-time error is now given if \c is not followed by an ASCII
609        character, that is, a byte less than 128. (In EBCDIC mode, the code is
610        different, and any byte value is allowed.)
612    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
613        START_OPTIMIZE option, which is now allowed at compile time - but just
614        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
615        to pcregrep and other applications that have no direct access to PCRE
616        options. The new /Y option in pcretest sets this option when calling
617        pcre_compile().
619    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
620        back references. Groups containing recursive back references were forced to
621        be atomic by that change, but in the case of named groups, the amount of
622        memory required was incorrectly computed, leading to "Failed: internal
623        error: code overflow". This has been fixed.
625    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
626        pcretest.c, to avoid build problems in some Borland environments.
629    Version 8.10 25-Jun-2010
630    ------------------------
632    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
633        THEN.
635    2.  (*ACCEPT) was not working when inside an atomic group.
637    3.  Inside a character class, \B is treated as a literal by default, but
638        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
639        causes the error). The code is unchanged, but I tidied the documentation.
641    4.  Inside a character class, PCRE always treated \R and \X as literals,
642        whereas Perl faults them if its -w option is set. I have changed PCRE so
643        that it faults them when PCRE_EXTRA is set.
645    5.  Added support for \N, which always matches any character other than
646        newline. (It is the same as "." when PCRE_DOTALL is not set.)
648    6.  When compiling pcregrep with newer versions of gcc which may have
649        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
650        declared with attribute warn_unused_result" were given. Just casting the
651        result to (void) does not stop the warnings; a more elaborate fudge is
652        needed. I've used a macro to implement this.
654    7.  Minor change to pcretest.c to avoid a compiler warning.
656    8.  Added four artifical Unicode properties to help with an option to make
657        \s etc use properties (see next item). The new properties are: Xan
658        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
660    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
661        use Unicode properties. (*UCP) at the start of a pattern can be used to set
662        this option. Modified pcretest to add /W to test this facility. Added
663        REG_UCP to make it available via the POSIX interface.
665    10. Added --line-buffered to pcregrep.
667    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
668        studied, and the match started with a letter with a code point greater than
669        127 whose first byte was different to the first byte of the other case of
670        the letter, the other case of this starting letter was not recognized
671        (#976).
673    12. If a pattern that was studied started with a repeated Unicode property
674        test, for example, \p{Nd}+, there was the theoretical possibility of
675        setting up an incorrect bitmap of starting bytes, but fortunately it could
676        not have actually happened in practice until change 8 above was made (it
677        added property types that matched character-matching opcodes).
679    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
680        possible starting bytes for non-anchored patterns.
682    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
683        \R, and also a number of cases that involve Unicode properties, both
684        explicit and implicit when PCRE_UCP is set.
686    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
687        input, it could crash or give wrong results if characters with values
688        greater than 0xc0 were present in the subject string. (Detail: it assumed
689        UTF-8 input when processing these items.)
691    16. Added a lot of (int) casts to avoid compiler warnings in systems where
692        size_t is 64-bit (#991).
694    17. Added a check for running out of memory when PCRE is compiled with
695        --disable-stack-for-recursion (#990).
697    18. If the last data line in a file for pcretest does not have a newline on
698        the end, a newline was missing in the output.
700    19. The default pcre_chartables.c file recognizes only ASCII characters (values
701        less than 128) in its various bitmaps. However, there is a facility for
702        generating tables according to the current locale when PCRE is compiled. It
703        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
704        characters, are recognized by isspace() and therefore were getting set in
705        these tables, and indeed these tables seem to approximate to ISO 8859. This
706        caused a problem in UTF-8 mode when pcre_study() was used to create a list
707        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
708        which of course cannot start UTF-8 characters. I have changed the code so
709        that only real ASCII characters (less than 128) and the correct starting
710        bytes for UTF-8 encodings are set for characters greater than 127 when in
711        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
712        altogether.)
714    20. Added the /T option to pcretest so as to be able to run tests with non-
715        standard character tables, thus making it possible to include the tests
716        used for 19 above in the standard set of tests.
718    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
719        reference to a subpattern the other side of a comment that contains an
720        opening parenthesis caused either an internal compiling error, or a
721        reference to the wrong subpattern.
724    Version 8.02 19-Mar-2010
725    ------------------------
727    1.  The Unicode data tables have been updated to Unicode 5.2.0.
729    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
730        configured.
732    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
733        original author of that file, following a query about its status.
735    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
736        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
738    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
739        quantifier applied to a forward-referencing subroutine call, could compile
740        incorrect code or give the error "internal error: previously-checked
741        referenced subpattern not found".
743    6.  Both MS Visual Studio and Symbian OS have problems with initializing
744        variables to point to external functions. For these systems, therefore,
745        pcre_malloc etc. are now initialized to local functions that call the
746        relevant global functions.
748    7.  There were two entries missing in the vectors called coptable and poptable
749        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
750        I've fixed the data, and added a kludgy way of testing at compile time that
751        the lengths are correct (equal to the number of opcodes).
753    8.  Following on from 7, I added a similar kludge to check the length of the
754        eint vector in pcreposix.c.
756    9.  Error texts for pcre_compile() are held as one long string to avoid too
757        much relocation at load time. To find a text, the string is searched,
758        counting zeros. There was no check for running off the end of the string,
759        which could happen if a new error number was added without updating the
760        string.
762    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
764    11. \K was not working if it appeared in an atomic group or in a group that
765        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
766        \K is "not well defined" if used in an assertion. PCRE now accepts it if
767        the assertion is positive, but not if it is negative.
769    12. Change 11 fortuitously reduced the size of the stack frame used in the
770        "match()" function of pcre_exec.c by one pointer. Forthcoming
771        implementation of support for (*MARK) will need an extra pointer on the
772        stack; I have reserved it now, so that the stack frame size does not
773        decrease.
775    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
776        item in branch that calls a recursion is a subroutine call - as in the
777        second branch in the above example - was incorrectly given the compile-
778        time error "recursive call could loop indefinitely" because pcre_compile()
779        was not correctly checking the subroutine for matching a non-empty string.
781    14. The checks for overrunning compiling workspace could trigger after an
782        overrun had occurred. This is a "should never occur" error, but it can be
783        triggered by pathological patterns such as hundreds of nested parentheses.
784        The checks now trigger 100 bytes before the end of the workspace.
786    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
789    Version 8.01 19-Jan-2010
790    ------------------------
792    1.  If a pattern contained a conditional subpattern with only one branch (in
793        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
794        computed the wrong minimum data length (which is of course zero for such
795        subpatterns). This could cause incorrect "no match" results.
797    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
798        the pattern is reset in the first branch, pcre_compile() failed with
799        "internal error: code overflow at offset...". This happened only when
800        the reset was to the original external option setting. (An optimization
801        abstracts leading options settings into an external setting, which was the
802        cause of this.)
804    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
805        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
806        assertion pattern did not match (meaning that the assertion was true), it
807        was incorrectly treated as false if the SKIP had been reached during the
808        matching. This also applied to assertions used as conditions.
810    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
811        assertion subpattern, including such a pattern used as a condition,
812        unpredictable results occurred, instead of the error return
815    5.  The C++ GlobalReplace function was not working like Perl for the special
816        situation when an empty string is matched. It now does the fancy magic
817        stuff that is necessary.
819    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
820        removed. (These were left over from very, very early versions of PCRE.)
822    7.  Some cosmetic changes to the code to make life easier when compiling it
823        as part of something else:
825        (a) Change DEBUG to PCRE_DEBUG.
827        (b) In pcre_compile(), rename the member of the "branch_chain" structure
828            called "current" as "current_branch", to prevent a collision with the
829            Linux macro when compiled as a kernel module.
831        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
832            prevent a collision with the Linux macro when compiled as a kernel
833            module.
835    8.  In pcre_compile() there are some checks for integer overflows that used to
836        cast potentially large values to (double). This has been changed to that
837        when building, a check for int64_t is made, and if it is found, it is used
838        instead, thus avoiding the use of floating point arithmetic. (There is no
839        other use of FP in PCRE.) If int64_t is not found, the fallback is to
840        double.
842    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
843        2005 (difference between two addresses compared to an unsigned value).
845    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
846        custom one, because of the following reported problem in Windows:
848          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
849              under Win32.
850          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
851              therefore missing the function definition.
852          - The compiler thus generates a "C" signature for the test function.
853          - The linker fails to find the "C" function.
854          - PCRE fails to configure if asked to do so against libbz2.
856    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
857        messages were output:
859          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
860          rerunning libtoolize, to keep the correct libtool macros in-tree.
861          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
863        I have done both of these things.
865    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
866        most of the time, it *can* run out if it is given a pattern that contains a
867        runaway infinite recursion. I updated the discussion in the pcrestack man
868        page.
870    13. Now that we have gone to the x.xx style of version numbers, the minor
871        version may start with zero. Using 08 or 09 is a bad idea because users
872        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
873        interpreted as invalid octal numbers. I've updated the previous comment in
874        configure.ac, and also added a check that gives an error if 08 or 09 are
875        used.
877    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
878        causing partial matching to fail when the end of the subject matched \W
879        in a UTF-8 pattern where \W was quantified with a minimum of 3.
881    15. There were some discrepancies between the declarations in pcre_internal.h
882        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
883        their definitions. The declarations used "const uschar *" and the
884        definitions used USPTR. Even though USPTR is normally defined as "const
885        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
886        reported that: "This difference in casting confuses some C++ compilers, for
887        example, SunCC recognizes above declarations as different functions and
888        generates broken code for hbpcre." I have changed the declarations to use
889        USPTR.
891    16. GNU libtool is named differently on some systems. The autogen.sh script now
892        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
893        (FreeBSD).
895    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
896        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
897        comment: "Figure out how to create a longlong from a string: strtoll and
898        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
899        instance, but it only takes 2 args instead of 3!"
901    18. A subtle bug concerned with back references has been fixed by a change of
902        specification, with a corresponding code fix. A pattern such as
903        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
904        refers, was giving matches when it shouldn't. For example, xa=xaaa would
905        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
906        same bug. Such groups have to be quantified to be useful, or contained
907        inside another quantified group. (If there's no repetition, the reference
908        can never match.) The problem arises because, having left the group and
909        moved on to the rest of the pattern, a later failure that backtracks into
910        the group uses the captured value from the final iteration of the group
911        rather than the correct earlier one. I have fixed this in PCRE by forcing
912        any group that contains a reference to itself to be an atomic group; that
913        is, there cannot be any backtracking into it once it has completed. This is
914        similar to recursive and subroutine calls.
917    Version 8.00 19-Oct-09
918    ----------------------
920    1.  The table for translating pcre_compile() error codes into POSIX error codes
921        was out-of-date, and there was no check on the pcre_compile() error code
922        being within the table. This could lead to an OK return being given in
923        error.
925    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
926        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
927        in a Windows environment.
929    3.  The pcregrep --count option prints the count for each file even when it is
930        zero, as does GNU grep. However, pcregrep was also printing all files when
931        --files-with-matches was added. Now, when both options are given, it prints
932        counts only for those files that have at least one match. (GNU grep just
933        prints the file name in this circumstance, but including the count seems
934        more useful - otherwise, why use --count?) Also ensured that the
935        combination -clh just lists non-zero counts, with no names.
937    4.  The long form of the pcregrep -F option was incorrectly implemented as
938        --fixed_strings instead of --fixed-strings. This is an incompatible change,
939        but it seems right to fix it, and I didn't think it was worth preserving
940        the old behaviour.
942    5.  The command line items --regex=pattern and --regexp=pattern were not
943        recognized by pcregrep, which required --regex pattern or --regexp pattern
944        (with a space rather than an '='). The man page documented the '=' forms,
945        which are compatible with GNU grep; these now work.
947    6.  No libpcreposix.pc file was created for pkg-config; there was just
948        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
950    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
951        when UCP support is not needed, by modifying the Python script that
952        generates it from Unicode data files. This should not matter if the module
953        is correctly used as a library, but I received one complaint about 50K of
954        unwanted data. My guess is that the person linked everything into his
955        program rather than using a library. Anyway, it does no harm.
957    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
958        was a minimum greater than 1 for a wide character in a possessive
959        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
960        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
961        character. Chaos in the form of incorrect output or a compiling loop could
962        result.
964    9.  The restrictions on what a pattern can contain when partial matching is
965        requested for pcre_exec() have been removed. All patterns can now be
966        partially matched by this function. In addition, if there are at least two
967        slots in the offset vector, the offset of the earliest inspected character
968        for the match and the offset of the end of the subject are set in them when
969        PCRE_ERROR_PARTIAL is returned.
971    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
972        synonymous with PCRE_PARTIAL, for backwards compatibility, and
973        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
974        and may be more useful for multi-segment matching.
976    11. Partial matching with pcre_exec() is now more intuitive. A partial match
977        used to be given if ever the end of the subject was reached; now it is
978        given only if matching could not proceed because another character was
979        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
980        string "Z", which now yields "no match" instead of "partial match". In the
981        case of pcre_dfa_exec(), "no match" is given if every matching path for the
982        final character ended with (*FAIL).
984    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
985        if the pattern had a "must contain" character that was already found in the
986        earlier partial match, unless partial matching was again requested. For
987        example, with the pattern /dog.(body)?/, the "must contain" character is
988        "g". If the first part-match was for the string "dog", restarting with
989        "sbody" failed. This bug has been fixed.
991    13. The string returned by pcre_dfa_exec() after a partial match has been
992        changed so that it starts at the first inspected character rather than the
993        first character of the match. This makes a difference only if the pattern
994        starts with a lookbehind assertion or \b or \B (\K is not supported by
995        pcre_dfa_exec()). It's an incompatible change, but it makes the two
996        matching functions compatible, and I think it's the right thing to do.
998    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
999        so that the demonstration program is easily available in environments where
1000        PCRE has not been installed from source.
1002    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1003        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1004        library.
1006    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1007        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1008        is not the first non-POSIX option to be added. Clearly some people find
1009        these options useful.
1011    17. If a caller to the POSIX matching function regexec() passes a non-zero
1012        value for nmatch with a NULL value for pmatch, the value of
1013        nmatch is forced to zero.
1015    18. RunGrepTest did not have a test for the availability of the -u option of
1016        the diff command, as RunTest does. It now checks in the same way as
1017        RunTest, and also checks for the -b option.
1019    19. If an odd number of negated classes containing just a single character
1020        interposed, within parentheses, between a forward reference to a named
1021        subpattern and the definition of the subpattern, compilation crashed with
1022        an internal error, complaining that it could not find the referenced
1023        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1024        [The bug was that it was starting one character too far in when skipping
1025        over the character class, thus treating the ] as data rather than
1026        terminating the class. This meant it could skip too much.]
1028    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1029        /g option in pcretest when the pattern contains \K, which makes it possible
1030        to have an empty string match not at the start, even when the pattern is
1031        anchored. Updated pcretest and pcredemo to use this option.
1033    21. If the maximum number of capturing subpatterns in a recursion was greater
1034        than the maximum at the outer level, the higher number was returned, but
1035        with unset values at the outer level. The correct (outer level) value is
1036        now given.
1038    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1039        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1040        make it do so. The string so far is captured, making this feature
1041        compatible with Perl.
1043    23. The tests have been re-organized, adding tests 11 and 12, to make it
1044        possible to check the Perl 5.10 features against Perl 5.10.
1046    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1047        pattern matches a fixed length string. PCRE did not allow this; now it
1048        does. Neither allows recursion.
1050    25. I finally figured out how to implement a request to provide the minimum
1051        length of subject string that was needed in order to match a given pattern.
1052        (It was back references and recursion that I had previously got hung up
1053        on.) This code has now been added to pcre_study(); it finds a lower bound
1054        to the length of subject needed. It is not necessarily the greatest lower
1055        bound, but using it to avoid searching strings that are too short does give
1056        some useful speed-ups. The value is available to calling programs via
1057        pcre_fullinfo().
1059    26. While implementing 25, I discovered to my embarrassment that pcretest had
1060        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1061        study optimizations had never been tested with that matching function.
1062        Oops. What is worse, even when it was passed study data, there was a bug in
1063        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1064        were also very few tests of studied patterns with pcre_dfa_exec().
1066    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1067        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1068        on the other side of the coin, they are no longer allowed to have different
1069        names, because these cannot be distinguished in PCRE, and this has caused
1070        confusion. (This is a difference from Perl.)
1072    28. When duplicate subpattern names are present (necessarily with different
1073        numbers, as required by 27 above), and a test is made by name in a
1074        conditional pattern, either for a subpattern having been matched, or for
1075        recursion in such a pattern, all the associated numbered subpatterns are
1076        tested, and the overall condition is true if the condition is true for any
1077        one of them. This is the way Perl works, and is also more like the way
1078        testing by number works.
1081  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
1082  ---------------------  ---------------------
# Line 112  Version 7.9 11-Apr-09 Line 1189  Version 7.9 11-Apr-09
1190  26. Changed a few more instances of "const unsigned char *" to USPTR, making  26. Changed a few more instances of "const unsigned char *" to USPTR, making
1191      the feature of a custom pointer more persuasive (as requested by a user).      the feature of a custom pointer more persuasive (as requested by a user).
1193  27. Wrapped the definitions of fileno and isatty for Windows, which appear in  27. Wrapped the definitions of fileno and isatty for Windows, which appear in
1194      pcretest.c, inside #ifndefs, because it seems they are sometimes already      pcretest.c, inside #ifndefs, because it seems they are sometimes already
1195      pre-defined.      pre-defined.
1197  28. Added support for (*UTF8) at the start of a pattern.  28. Added support for (*UTF8) at the start of a pattern.
1199  29. Arrange for flags added by the "release type" setting in CMake to be shown  29. Arrange for flags added by the "release type" setting in CMake to be shown
1200      in the configuration summary.      in the configuration summary.

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