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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.00 ??-???-??  Version 8.11 10-Oct-2010
5    ------------------------
6    
7    1.  (*THEN) was not working properly if there were untried alternatives prior
8        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
9        backtracked to try for "b" instead of moving to the next alternative branch
10        at the same level (in this case, to look for "c"). The Perl documentation
11        is clear that when (*THEN) is backtracked onto, it goes to the "next
12        alternative in the innermost enclosing group".
13    
14    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
15        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
16        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
17        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
18        (*THEN).
19    
20    
21    Version 8.10 25-Jun-2010
22    ------------------------
23    
24    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
25        THEN.
26    
27    2.  (*ACCEPT) was not working when inside an atomic group.
28    
29    3.  Inside a character class, \B is treated as a literal by default, but
30        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
31        causes the error). The code is unchanged, but I tidied the documentation.
32    
33    4.  Inside a character class, PCRE always treated \R and \X as literals,
34        whereas Perl faults them if its -w option is set. I have changed PCRE so
35        that it faults them when PCRE_EXTRA is set.
36    
37    5.  Added support for \N, which always matches any character other than
38        newline. (It is the same as "." when PCRE_DOTALL is not set.)
39    
40    6.  When compiling pcregrep with newer versions of gcc which may have
41        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
42        declared with attribute warn_unused_result" were given. Just casting the
43        result to (void) does not stop the warnings; a more elaborate fudge is
44        needed. I've used a macro to implement this.
45    
46    7.  Minor change to pcretest.c to avoid a compiler warning.
47    
48    8.  Added four artifical Unicode properties to help with an option to make
49        \s etc use properties (see next item). The new properties are: Xan
50        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
51    
52    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
53        use Unicode properties. (*UCP) at the start of a pattern can be used to set
54        this option. Modified pcretest to add /W to test this facility. Added
55        REG_UCP to make it available via the POSIX interface.
56    
57    10. Added --line-buffered to pcregrep.
58    
59    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
60        studied, and the match started with a letter with a code point greater than
61        127 whose first byte was different to the first byte of the other case of
62        the letter, the other case of this starting letter was not recognized
63        (#976).
64    
65    12. If a pattern that was studied started with a repeated Unicode property
66        test, for example, \p{Nd}+, there was the theoretical possibility of
67        setting up an incorrect bitmap of starting bytes, but fortunately it could
68        not have actually happened in practice until change 8 above was made (it
69        added property types that matched character-matching opcodes).
70    
71    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
72        possible starting bytes for non-anchored patterns.
73    
74    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
75        \R, and also a number of cases that involve Unicode properties, both
76        explicit and implicit when PCRE_UCP is set.
77    
78    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
79        input, it could crash or give wrong results if characters with values
80        greater than 0xc0 were present in the subject string. (Detail: it assumed
81        UTF-8 input when processing these items.)
82    
83    16. Added a lot of (int) casts to avoid compiler warnings in systems where
84        size_t is 64-bit (#991).
85    
86    17. Added a check for running out of memory when PCRE is compiled with
87        --disable-stack-for-recursion (#990).
88    
89    18. If the last data line in a file for pcretest does not have a newline on
90        the end, a newline was missing in the output.
91    
92    19. The default pcre_chartables.c file recognizes only ASCII characters (values
93        less than 128) in its various bitmaps. However, there is a facility for
94        generating tables according to the current locale when PCRE is compiled. It
95        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
96        characters, are recognized by isspace() and therefore were getting set in
97        these tables, and indeed these tables seem to approximate to ISO 8859. This
98        caused a problem in UTF-8 mode when pcre_study() was used to create a list
99        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
100        which of course cannot start UTF-8 characters. I have changed the code so
101        that only real ASCII characters (less than 128) and the correct starting
102        bytes for UTF-8 encodings are set for characters greater than 127 when in
103        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
104        altogether.)
105    
106    20. Added the /T option to pcretest so as to be able to run tests with non-
107        standard character tables, thus making it possible to include the tests
108        used for 19 above in the standard set of tests.
109    
110    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
111        reference to a subpattern the other side of a comment that contains an
112        opening parenthesis caused either an internal compiling error, or a
113        reference to the wrong subpattern.
114    
115    
116    Version 8.02 19-Mar-2010
117    ------------------------
118    
119    1.  The Unicode data tables have been updated to Unicode 5.2.0.
120    
121    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
122        configured.
123    
124    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
125        original author of that file, following a query about its status.
126    
127    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
128        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
129    
130    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
131        quantifier applied to a forward-referencing subroutine call, could compile
132        incorrect code or give the error "internal error: previously-checked
133        referenced subpattern not found".
134    
135    6.  Both MS Visual Studio and Symbian OS have problems with initializing
136        variables to point to external functions. For these systems, therefore,
137        pcre_malloc etc. are now initialized to local functions that call the
138        relevant global functions.
139    
140    7.  There were two entries missing in the vectors called coptable and poptable
141        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
142        I've fixed the data, and added a kludgy way of testing at compile time that
143        the lengths are correct (equal to the number of opcodes).
144    
145    8.  Following on from 7, I added a similar kludge to check the length of the
146        eint vector in pcreposix.c.
147    
148    9.  Error texts for pcre_compile() are held as one long string to avoid too
149        much relocation at load time. To find a text, the string is searched,
150        counting zeros. There was no check for running off the end of the string,
151        which could happen if a new error number was added without updating the
152        string.
153    
154    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
155    
156    11. \K was not working if it appeared in an atomic group or in a group that
157        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
158        \K is "not well defined" if used in an assertion. PCRE now accepts it if
159        the assertion is positive, but not if it is negative.
160    
161    12. Change 11 fortuitously reduced the size of the stack frame used in the
162        "match()" function of pcre_exec.c by one pointer. Forthcoming
163        implementation of support for (*MARK) will need an extra pointer on the
164        stack; I have reserved it now, so that the stack frame size does not
165        decrease.
166    
167    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
168        item in branch that calls a recursion is a subroutine call - as in the
169        second branch in the above example - was incorrectly given the compile-
170        time error "recursive call could loop indefinitely" because pcre_compile()
171        was not correctly checking the subroutine for matching a non-empty string.
172    
173    14. The checks for overrunning compiling workspace could trigger after an
174        overrun had occurred. This is a "should never occur" error, but it can be
175        triggered by pathological patterns such as hundreds of nested parentheses.
176        The checks now trigger 100 bytes before the end of the workspace.
177    
178    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
179    
180    
181    Version 8.01 19-Jan-2010
182    ------------------------
183    
184    1.  If a pattern contained a conditional subpattern with only one branch (in
185        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
186        computed the wrong minimum data length (which is of course zero for such
187        subpatterns). This could cause incorrect "no match" results.
188    
189    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
190        the pattern is reset in the first branch, pcre_compile() failed with
191        "internal error: code overflow at offset...". This happened only when
192        the reset was to the original external option setting. (An optimization
193        abstracts leading options settings into an external setting, which was the
194        cause of this.)
195    
196    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
197        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
198        assertion pattern did not match (meaning that the assertion was true), it
199        was incorrectly treated as false if the SKIP had been reached during the
200        matching. This also applied to assertions used as conditions.
201    
202    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
203        assertion subpattern, including such a pattern used as a condition,
204        unpredictable results occurred, instead of the error return
205        PCRE_ERROR_DFA_UITEM.
206    
207    5.  The C++ GlobalReplace function was not working like Perl for the special
208        situation when an empty string is matched. It now does the fancy magic
209        stuff that is necessary.
210    
211    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
212        removed. (These were left over from very, very early versions of PCRE.)
213    
214    7.  Some cosmetic changes to the code to make life easier when compiling it
215        as part of something else:
216    
217        (a) Change DEBUG to PCRE_DEBUG.
218    
219        (b) In pcre_compile(), rename the member of the "branch_chain" structure
220            called "current" as "current_branch", to prevent a collision with the
221            Linux macro when compiled as a kernel module.
222    
223        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
224            prevent a collision with the Linux macro when compiled as a kernel
225            module.
226    
227    8.  In pcre_compile() there are some checks for integer overflows that used to
228        cast potentially large values to (double). This has been changed to that
229        when building, a check for int64_t is made, and if it is found, it is used
230        instead, thus avoiding the use of floating point arithmetic. (There is no
231        other use of FP in PCRE.) If int64_t is not found, the fallback is to
232        double.
233    
234    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
235        2005 (difference between two addresses compared to an unsigned value).
236    
237    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
238        custom one, because of the following reported problem in Windows:
239    
240          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
241              under Win32.
242          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
243              therefore missing the function definition.
244          - The compiler thus generates a "C" signature for the test function.
245          - The linker fails to find the "C" function.
246          - PCRE fails to configure if asked to do so against libbz2.
247    
248    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
249        messages were output:
250    
251          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
252          rerunning libtoolize, to keep the correct libtool macros in-tree.
253          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
254    
255        I have done both of these things.
256    
257    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
258        most of the time, it *can* run out if it is given a pattern that contains a
259        runaway infinite recursion. I updated the discussion in the pcrestack man
260        page.
261    
262    13. Now that we have gone to the x.xx style of version numbers, the minor
263        version may start with zero. Using 08 or 09 is a bad idea because users
264        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
265        interpreted as invalid octal numbers. I've updated the previous comment in
266        configure.ac, and also added a check that gives an error if 08 or 09 are
267        used.
268    
269    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
270        causing partial matching to fail when the end of the subject matched \W
271        in a UTF-8 pattern where \W was quantified with a minimum of 3.
272    
273    15. There were some discrepancies between the declarations in pcre_internal.h
274        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
275        their definitions. The declarations used "const uschar *" and the
276        definitions used USPTR. Even though USPTR is normally defined as "const
277        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
278        reported that: "This difference in casting confuses some C++ compilers, for
279        example, SunCC recognizes above declarations as different functions and
280        generates broken code for hbpcre." I have changed the declarations to use
281        USPTR.
282    
283    16. GNU libtool is named differently on some systems. The autogen.sh script now
284        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
285        (FreeBSD).
286    
287    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
288        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
289        comment: "Figure out how to create a longlong from a string: strtoll and
290        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
291        instance, but it only takes 2 args instead of 3!"
292    
293    18. A subtle bug concerned with back references has been fixed by a change of
294        specification, with a corresponding code fix. A pattern such as
295        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
296        refers, was giving matches when it shouldn't. For example, xa=xaaa would
297        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
298        same bug. Such groups have to be quantified to be useful, or contained
299        inside another quantified group. (If there's no repetition, the reference
300        can never match.) The problem arises because, having left the group and
301        moved on to the rest of the pattern, a later failure that backtracks into
302        the group uses the captured value from the final iteration of the group
303        rather than the correct earlier one. I have fixed this in PCRE by forcing
304        any group that contains a reference to itself to be an atomic group; that
305        is, there cannot be any backtracking into it once it has completed. This is
306        similar to recursive and subroutine calls.
307    
308    
309    Version 8.00 19-Oct-09
310  ----------------------  ----------------------
311    
312  1.  The table for translating pcre_compile() error codes into POSIX error codes  1.  The table for translating pcre_compile() error codes into POSIX error codes
313      was out-of-date, and there was no check on the pcre_compile() error code      was out-of-date, and there was no check on the pcre_compile() error code
314      being within the table. This could lead to an OK return being given in      being within the table. This could lead to an OK return being given in
315      error.      error.
316    
317  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
318      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
319      in a Windows environment.      in a Windows environment.
320    
321  3.  The pcregrep --count option prints the count for each file even when it is  3.  The pcregrep --count option prints the count for each file even when it is
322      zero, as does GNU grep. However, pcregrep was also printing all files when      zero, as does GNU grep. However, pcregrep was also printing all files when
323      --files-with-matches was added. Now, when both options are given, it prints      --files-with-matches was added. Now, when both options are given, it prints
324      counts only for those files that have at least one match. (GNU grep just      counts only for those files that have at least one match. (GNU grep just
325      prints the file name in this circumstance, but including the count seems      prints the file name in this circumstance, but including the count seems
326      more useful - otherwise, why use --count?) Also ensured that the      more useful - otherwise, why use --count?) Also ensured that the
327      combination -clh just lists non-zero counts, with no names.      combination -clh just lists non-zero counts, with no names.
328    
329  4.  The long form of the pcregrep -F option was incorrectly implemented as  4.  The long form of the pcregrep -F option was incorrectly implemented as
330      --fixed_strings instead of --fixed-strings. This is an incompatible change,      --fixed_strings instead of --fixed-strings. This is an incompatible change,
331      but it seems right to fix it, and I didn't think it was worth preserving      but it seems right to fix it, and I didn't think it was worth preserving
332      the old behaviour.      the old behaviour.
333    
334  5.  The command line items --regex=pattern and --regexp=pattern were not  5.  The command line items --regex=pattern and --regexp=pattern were not
335      recognized by pcregrep, which required --regex pattern or --regexp pattern      recognized by pcregrep, which required --regex pattern or --regexp pattern
336      (with a space rather than an '='). The man page documented the '=' forms,      (with a space rather than an '='). The man page documented the '=' forms,
337      which are compatible with GNU grep; these now work.      which are compatible with GNU grep; these now work.
338    
339  6.  No libpcreposix.pc file was created for pkg-config; there was just  6.  No libpcreposix.pc file was created for pkg-config; there was just
340      libpcre.pc and libpcrecpp.pc. The omission has been rectified.      libpcre.pc and libpcrecpp.pc. The omission has been rectified.
341    
342  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
343      when UCP support is not needed, by modifying the Python script that      when UCP support is not needed, by modifying the Python script that
344      generates it from Unicode data files. This should not matter if the module      generates it from Unicode data files. This should not matter if the module
345      is correctly used as a library, but I received one complaint about 50K of      is correctly used as a library, but I received one complaint about 50K of
346      unwanted data. My guess is that the person linked everything into his      unwanted data. My guess is that the person linked everything into his
347      program rather than using a library. Anyway, it does no harm.      program rather than using a library. Anyway, it does no harm.
348    
349  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
350      was a minimum greater than 1 for a wide character in a possessive      was a minimum greater than 1 for a wide character in a possessive
351      repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8      repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
352      which had an unlimited repeat of a nested, fixed maximum repeat of a wide      which had an unlimited repeat of a nested, fixed maximum repeat of a wide
353      character. Chaos in the form of incorrect output or a compiling loop could      character. Chaos in the form of incorrect output or a compiling loop could
354      result.      result.
355    
356  9.  The restrictions on what a pattern can contain when partial matching is  9.  The restrictions on what a pattern can contain when partial matching is
357      requested for pcre_exec() have been removed. All patterns can now be      requested for pcre_exec() have been removed. All patterns can now be
358      partially matched by this function. In addition, if there are at least two      partially matched by this function. In addition, if there are at least two
359      slots in the offset vector, the offset of the earliest inspected character      slots in the offset vector, the offset of the earliest inspected character
360      for the match and the offset of the end of the subject are set in them when      for the match and the offset of the end of the subject are set in them when
361      PCRE_ERROR_PARTIAL is returned.      PCRE_ERROR_PARTIAL is returned.
362    
363  10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is  10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
364      synonymous with PCRE_PARTIAL, for backwards compatibility, and      synonymous with PCRE_PARTIAL, for backwards compatibility, and
365      PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,      PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
366      and may be more useful for multi-segment matching, especially with      and may be more useful for multi-segment matching.
367      pcre_exec().  
368    11. Partial matching with pcre_exec() is now more intuitive. A partial match
369  11. Partial matching with pcre_exec() is now more intuitive. A partial match      used to be given if ever the end of the subject was reached; now it is
370      used to be given if ever the end of the subject was reached; now it is      given only if matching could not proceed because another character was
371      given only if matching could not proceed because another character was      needed. This makes a difference in some odd cases such as Z(*FAIL) with the
372      needed. This makes a difference in some odd cases such as Z(*FAIL) with the      string "Z", which now yields "no match" instead of "partial match". In the
373      string "Z", which now yields "no match" instead of "partial match". In the      case of pcre_dfa_exec(), "no match" is given if every matching path for the
374      case of pcre_dfa_exec(), "no match" is given if every matching path for the      final character ended with (*FAIL).
375      final character ended with (*FAIL).  
   
376  12. Restarting a match using pcre_dfa_exec() after a partial match did not work  12. Restarting a match using pcre_dfa_exec() after a partial match did not work
377      if the pattern had a "must contain" character that was already found in the      if the pattern had a "must contain" character that was already found in the
378      earlier partial match, unless partial matching was again requested. For      earlier partial match, unless partial matching was again requested. For
379      example, with the pattern /dog.(body)?/, the "must contain" character is      example, with the pattern /dog.(body)?/, the "must contain" character is
380      "g". If the first part-match was for the string "dog", restarting with      "g". If the first part-match was for the string "dog", restarting with
381      "sbody" failed. This bug has been fixed.      "sbody" failed. This bug has been fixed.
382    
383  13. The string returned by pcre_dfa_exec() after a partial match has been  13. The string returned by pcre_dfa_exec() after a partial match has been
384      changed so that it starts at the first inspected character rather than the      changed so that it starts at the first inspected character rather than the
385      first character of the match. This makes a difference only if the pattern      first character of the match. This makes a difference only if the pattern
386      starts with a lookbehind assertion or \b or \B (\K is not supported by      starts with a lookbehind assertion or \b or \B (\K is not supported by
387      pcre_dfa_exec()). It's an incompatible change, but it makes the two      pcre_dfa_exec()). It's an incompatible change, but it makes the two
388      matching functions compatible, and I think it's the right thing to do.      matching functions compatible, and I think it's the right thing to do.
389    
390  14. Added a pcredemo man page, created automatically from the pcredemo.c file,  14. Added a pcredemo man page, created automatically from the pcredemo.c file,
391      so that the demonstration program is easily available in environments where      so that the demonstration program is easily available in environments where
392      PCRE has not been installed from source.      PCRE has not been installed from source.
393    
394  15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,  15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
395      libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared      libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
396      library.      library.
397    
398  16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.  16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
399      It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it      It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
400      is not the first non-POSIX option to be added. Clearly some people find      is not the first non-POSIX option to be added. Clearly some people find
401      these options useful.      these options useful.
402    
403  17. If a caller to the POSIX matching function regexec() passes a non-zero  17. If a caller to the POSIX matching function regexec() passes a non-zero
404      value for nmatch with a NULL value for pmatch, the value of      value for nmatch with a NULL value for pmatch, the value of
405      nmatch is forced to zero.      nmatch is forced to zero.
406    
407  18. RunGrepTest did not have a test for the availability of the -u option of  18. RunGrepTest did not have a test for the availability of the -u option of
408      the diff command, as RunTest does. It now checks in the same way as      the diff command, as RunTest does. It now checks in the same way as
409      RunTest, and also checks for the -b option.      RunTest, and also checks for the -b option.
410    
411  19. If an odd number of negated classes containing just a single character  19. If an odd number of negated classes containing just a single character
412      interposed, within parentheses, between a forward reference to a named      interposed, within parentheses, between a forward reference to a named
413      subpattern and the definition of the subpattern, compilation crashed with      subpattern and the definition of the subpattern, compilation crashed with
414      an internal error, complaining that it could not find the referenced      an internal error, complaining that it could not find the referenced
415      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
416      [The bug was that it was starting one character too far in when skipping      [The bug was that it was starting one character too far in when skipping
417      over the character class, thus treating the ] as data rather than      over the character class, thus treating the ] as data rather than
418      terminating the class. This meant it could skip too much.]      terminating the class. This meant it could skip too much.]
419    
420    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
421        /g option in pcretest when the pattern contains \K, which makes it possible
422        to have an empty string match not at the start, even when the pattern is
423        anchored. Updated pcretest and pcredemo to use this option.
424    
425    21. If the maximum number of capturing subpatterns in a recursion was greater
426        than the maximum at the outer level, the higher number was returned, but
427        with unset values at the outer level. The correct (outer level) value is
428        now given.
429    
430    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
431        PCRE did not set those parentheses (unlike Perl). I have now found a way to
432        make it do so. The string so far is captured, making this feature
433        compatible with Perl.
434    
435    23. The tests have been re-organized, adding tests 11 and 12, to make it
436        possible to check the Perl 5.10 features against Perl 5.10.
437    
438    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
439        pattern matches a fixed length string. PCRE did not allow this; now it
440        does. Neither allows recursion.
441    
442    25. I finally figured out how to implement a request to provide the minimum
443        length of subject string that was needed in order to match a given pattern.
444        (It was back references and recursion that I had previously got hung up
445        on.) This code has now been added to pcre_study(); it finds a lower bound
446        to the length of subject needed. It is not necessarily the greatest lower
447        bound, but using it to avoid searching strings that are too short does give
448        some useful speed-ups. The value is available to calling programs via
449        pcre_fullinfo().
450    
451    26. While implementing 25, I discovered to my embarrassment that pcretest had
452        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
453        study optimizations had never been tested with that matching function.
454        Oops. What is worse, even when it was passed study data, there was a bug in
455        pcre_dfa_exec() that meant it never actually used it. Double oops. There
456        were also very few tests of studied patterns with pcre_dfa_exec().
457    
458    27. If (?| is used to create subpatterns with duplicate numbers, they are now
459        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
460        on the other side of the coin, they are no longer allowed to have different
461        names, because these cannot be distinguished in PCRE, and this has caused
462        confusion. (This is a difference from Perl.)
463    
464    28. When duplicate subpattern names are present (necessarily with different
465        numbers, as required by 27 above), and a test is made by name in a
466        conditional pattern, either for a subpattern having been matched, or for
467        recursion in such a pattern, all the associated numbered subpatterns are
468        tested, and the overall condition is true if the condition is true for any
469        one of them. This is the way Perl works, and is also more like the way
470        testing by number works.
471    
472    
473  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
474  ---------------------  ---------------------

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