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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.00 ??-???-??  Version 8.10 03-Jun-2010
5    ------------------------
6    
7    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
8        THEN.
9    
10    2.  (*ACCEPT) was not working when inside an atomic group.
11    
12    3.  Inside a character class, \B is treated as a literal by default, but
13        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
14        causes the error). The code is unchanged, but I tidied the documentation.
15    
16    4.  Inside a character class, PCRE always treated \R and \X as literals,
17        whereas Perl faults them if its -w option is set. I have changed PCRE so
18        that it faults them when PCRE_EXTRA is set.
19    
20    5.  Added support for \N, which always matches any character other than
21        newline. (It is the same as "." when PCRE_DOTALL is not set.)
22    
23    6.  When compiling pcregrep with newer versions of gcc which may have
24        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
25        declared with attribute warn_unused_result" were given. Just casting the
26        result to (void) does not stop the warnings; a more elaborate fudge is
27        needed. I've used a macro to implement this.
28    
29    7.  Minor change to pcretest.c to avoid a compiler warning.
30    
31    8.  Added four artifical Unicode properties to help with an option to make
32        \s etc use properties (see next item). The new properties are: Xan
33        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
34    
35    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
36        use Unicode properties. (*UCP) at the start of a pattern can be used to set
37        this option. Modified pcretest to add /W to test this facility. Added
38        REG_UCP to make it available via the POSIX interface.
39    
40    10. Added --line-buffered to pcregrep.
41    
42    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
43        studied, and the match started with a letter with a code point greater than
44        127 whose first byte was different to the first byte of the other case of
45        the letter, the other case of this starting letter was not recognized
46        (#976).
47    
48    12. If a pattern that was studied started with a repeated Unicode property
49        test, for example, \p{Nd}+, there was the theoretical possibility of
50        setting up an incorrect bitmap of starting bytes, but fortunately it could
51        not have actually happened in practice until change 8 above was made (it
52        added property types that matched character-matching opcodes).
53    
54    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
55        possible starting bytes for non-anchored patterns.
56    
57    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
58        \R, and also a number of cases that involve Unicode properties, both
59        explicit and implicit when PCRE_UCP is set.
60    
61    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
62        input, it could crash or give wrong results if characters with values
63        greater than 0xc0 were present in the subject string. (Detail: it assumed
64        UTF-8 input when processing these items.)
65    
66    16. Added a lot of (int) casts to avoid compiler warnings in systems where
67        size_t is 64-bit (#991).
68    
69    17. Added a check for running out of memory when PCRE is compiled with
70        --disable-stack-for-recursion (#990).
71    
72    18. If the last data line in a file for pcretest does not have a newline on
73        the end, a newline was missing in the output.
74    
75    19. The default pcre_chartables.c file recognizes only ASCII characters (values
76        less than 128) in its various bitmaps. However, there is a facility for
77        generating tables according to the current locale when PCRE is compiled. It
78        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
79        characters, are recognized by isspace() and therefore were getting set in
80        these tables, and indeed these tables seem to approximate to ISO 8859. This
81        caused a problem in UTF-8 mode when pcre_study() was used to create a list
82        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
83        which of course cannot start UTF-8 characters. I have changed the code so
84        that only real ASCII characters (less than 128) and the correct starting
85        bytes for UTF-8 encodings are set for characters greater than 127 when in
86        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
87        altogether.)
88    
89    20. Added the /T option to pcretest so as to be able to run tests with non-
90        standard character tables, thus making it possible to include the tests
91        used for 19 above in the standard set of tests.
92    
93    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
94        reference to a subpattern the other side of a comment that contains an
95        opening parenthesis caused either an internal compiling error, or a
96        reference to the wrong subpattern.
97    
98    
99    Version 8.02 19-Mar-2010
100    ------------------------
101    
102    1.  The Unicode data tables have been updated to Unicode 5.2.0.
103    
104    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
105        configured.
106    
107    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
108        original author of that file, following a query about its status.
109    
110    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
111        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
112    
113    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
114        quantifier applied to a forward-referencing subroutine call, could compile
115        incorrect code or give the error "internal error: previously-checked
116        referenced subpattern not found".
117    
118    6.  Both MS Visual Studio and Symbian OS have problems with initializing
119        variables to point to external functions. For these systems, therefore,
120        pcre_malloc etc. are now initialized to local functions that call the
121        relevant global functions.
122    
123    7.  There were two entries missing in the vectors called coptable and poptable
124        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
125        I've fixed the data, and added a kludgy way of testing at compile time that
126        the lengths are correct (equal to the number of opcodes).
127    
128    8.  Following on from 7, I added a similar kludge to check the length of the
129        eint vector in pcreposix.c.
130    
131    9.  Error texts for pcre_compile() are held as one long string to avoid too
132        much relocation at load time. To find a text, the string is searched,
133        counting zeros. There was no check for running off the end of the string,
134        which could happen if a new error number was added without updating the
135        string.
136    
137    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
138    
139    11. \K was not working if it appeared in an atomic group or in a group that
140        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
141        \K is "not well defined" if used in an assertion. PCRE now accepts it if
142        the assertion is positive, but not if it is negative.
143    
144    12. Change 11 fortuitously reduced the size of the stack frame used in the
145        "match()" function of pcre_exec.c by one pointer. Forthcoming
146        implementation of support for (*MARK) will need an extra pointer on the
147        stack; I have reserved it now, so that the stack frame size does not
148        decrease.
149    
150    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
151        item in branch that calls a recursion is a subroutine call - as in the
152        second branch in the above example - was incorrectly given the compile-
153        time error "recursive call could loop indefinitely" because pcre_compile()
154        was not correctly checking the subroutine for matching a non-empty string.
155    
156    14. The checks for overrunning compiling workspace could trigger after an
157        overrun had occurred. This is a "should never occur" error, but it can be
158        triggered by pathological patterns such as hundreds of nested parentheses.
159        The checks now trigger 100 bytes before the end of the workspace.
160    
161    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
162    
163    
164    Version 8.01 19-Jan-2010
165    ------------------------
166    
167    1.  If a pattern contained a conditional subpattern with only one branch (in
168        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
169        computed the wrong minimum data length (which is of course zero for such
170        subpatterns). This could cause incorrect "no match" results.
171    
172    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
173        the pattern is reset in the first branch, pcre_compile() failed with
174        "internal error: code overflow at offset...". This happened only when
175        the reset was to the original external option setting. (An optimization
176        abstracts leading options settings into an external setting, which was the
177        cause of this.)
178    
179    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
180        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
181        assertion pattern did not match (meaning that the assertion was true), it
182        was incorrectly treated as false if the SKIP had been reached during the
183        matching. This also applied to assertions used as conditions.
184    
185    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
186        assertion subpattern, including such a pattern used as a condition,
187        unpredictable results occurred, instead of the error return
188        PCRE_ERROR_DFA_UITEM.
189    
190    5.  The C++ GlobalReplace function was not working like Perl for the special
191        situation when an empty string is matched. It now does the fancy magic
192        stuff that is necessary.
193    
194    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
195        removed. (These were left over from very, very early versions of PCRE.)
196    
197    7.  Some cosmetic changes to the code to make life easier when compiling it
198        as part of something else:
199    
200        (a) Change DEBUG to PCRE_DEBUG.
201    
202        (b) In pcre_compile(), rename the member of the "branch_chain" structure
203            called "current" as "current_branch", to prevent a collision with the
204            Linux macro when compiled as a kernel module.
205    
206        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
207            prevent a collision with the Linux macro when compiled as a kernel
208            module.
209    
210    8.  In pcre_compile() there are some checks for integer overflows that used to
211        cast potentially large values to (double). This has been changed to that
212        when building, a check for int64_t is made, and if it is found, it is used
213        instead, thus avoiding the use of floating point arithmetic. (There is no
214        other use of FP in PCRE.) If int64_t is not found, the fallback is to
215        double.
216    
217    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
218        2005 (difference between two addresses compared to an unsigned value).
219    
220    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
221        custom one, because of the following reported problem in Windows:
222    
223          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
224              under Win32.
225          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
226              therefore missing the function definition.
227          - The compiler thus generates a "C" signature for the test function.
228          - The linker fails to find the "C" function.
229          - PCRE fails to configure if asked to do so against libbz2.
230    
231    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
232        messages were output:
233    
234          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
235          rerunning libtoolize, to keep the correct libtool macros in-tree.
236          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
237    
238        I have done both of these things.
239    
240    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
241        most of the time, it *can* run out if it is given a pattern that contains a
242        runaway infinite recursion. I updated the discussion in the pcrestack man
243        page.
244    
245    13. Now that we have gone to the x.xx style of version numbers, the minor
246        version may start with zero. Using 08 or 09 is a bad idea because users
247        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
248        interpreted as invalid octal numbers. I've updated the previous comment in
249        configure.ac, and also added a check that gives an error if 08 or 09 are
250        used.
251    
252    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
253        causing partial matching to fail when the end of the subject matched \W
254        in a UTF-8 pattern where \W was quantified with a minimum of 3.
255    
256    15. There were some discrepancies between the declarations in pcre_internal.h
257        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
258        their definitions. The declarations used "const uschar *" and the
259        definitions used USPTR. Even though USPTR is normally defined as "const
260        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
261        reported that: "This difference in casting confuses some C++ compilers, for
262        example, SunCC recognizes above declarations as different functions and
263        generates broken code for hbpcre." I have changed the declarations to use
264        USPTR.
265    
266    16. GNU libtool is named differently on some systems. The autogen.sh script now
267        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
268        (FreeBSD).
269    
270    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
271        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
272        comment: "Figure out how to create a longlong from a string: strtoll and
273        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
274        instance, but it only takes 2 args instead of 3!"
275    
276    18. A subtle bug concerned with back references has been fixed by a change of
277        specification, with a corresponding code fix. A pattern such as
278        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
279        refers, was giving matches when it shouldn't. For example, xa=xaaa would
280        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
281        same bug. Such groups have to be quantified to be useful, or contained
282        inside another quantified group. (If there's no repetition, the reference
283        can never match.) The problem arises because, having left the group and
284        moved on to the rest of the pattern, a later failure that backtracks into
285        the group uses the captured value from the final iteration of the group
286        rather than the correct earlier one. I have fixed this in PCRE by forcing
287        any group that contains a reference to itself to be an atomic group; that
288        is, there cannot be any backtracking into it once it has completed. This is
289        similar to recursive and subroutine calls.
290    
291    
292    Version 8.00 19-Oct-09
293  ----------------------  ----------------------
294    
295  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
296      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
297      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
298      error.      error.
299    
300  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,
301      "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
302      in a Windows environment.      in a Windows environment.
303    
304  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
305      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
306      --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
307      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
308      prints the file name in this circumstance, but including the count seems      prints the file name in this circumstance, but including the count seems
309      more useful - otherwise, why use --count?) Also ensured that the      more useful - otherwise, why use --count?) Also ensured that the
310      combination -clh just lists non-zero counts, with no names.      combination -clh just lists non-zero counts, with no names.
311    
312  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
313      --fixed_strings instead of --fixed-strings. This is an incompatible change,      --fixed_strings instead of --fixed-strings. This is an incompatible change,
314      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
315      the old behaviour.      the old behaviour.
316    
317  5.  The command line items --regex=pattern and --regexp=pattern were not  5.  The command line items --regex=pattern and --regexp=pattern were not
318      recognized by pcregrep, which required --regex pattern or --regexp pattern      recognized by pcregrep, which required --regex pattern or --regexp pattern
319      (with a space rather than an '='). The man page documented the '=' forms,      (with a space rather than an '='). The man page documented the '=' forms,
320      which are compatible with GNU grep; these now work.      which are compatible with GNU grep; these now work.
321    
322  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
323      libpcre.pc and libpcrecpp.pc. The omission has been rectified.      libpcre.pc and libpcrecpp.pc. The omission has been rectified.
324    
325  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
326      when UCP support is not needed, by modifying the Python script that      when UCP support is not needed, by modifying the Python script that
327      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
328      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
329      unwanted data. My guess is that the person linked everything into his      unwanted data. My guess is that the person linked everything into his
330      program rather than using a library. Anyway, it does no harm.      program rather than using a library. Anyway, it does no harm.
331    
332  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
333      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
334      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
335      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
336      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
337      result.      result.
338    
339  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
340      requested for pcre_exec() have been removed. All patterns can now be      requested for pcre_exec() have been removed. All patterns can now be
341      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
342      slots in the offset vector, the offset of the earliest inspected character      slots in the offset vector, the offset of the earliest inspected character
343      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
344      PCRE_ERROR_PARTIAL is returned.      PCRE_ERROR_PARTIAL is returned.
345    
346  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
347      synonymous with PCRE_PARTIAL, for backwards compatibility, and      synonymous with PCRE_PARTIAL, for backwards compatibility, and
348      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,
349      and may be more useful for multi-segment matching, especially with      and may be more useful for multi-segment matching.
350      pcre_exec().  
351    11. Partial matching with pcre_exec() is now more intuitive. A partial match
352  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
353      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
354      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
355      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
356      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
357      case of pcre_dfa_exec(), "no match" is given if every matching path for the      final character ended with (*FAIL).
358      final character ended with (*FAIL).  
   
359  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
360      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
361      earlier partial match, unless partial matching was again requested. For      earlier partial match, unless partial matching was again requested. For
362      example, with the pattern /dog.(body)?/, the "must contain" character is      example, with the pattern /dog.(body)?/, the "must contain" character is
363      "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
364      "sbody" failed. This bug has been fixed.      "sbody" failed. This bug has been fixed.
365    
366  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
367      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
368      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
369      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
370      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
371      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.
372    
373  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,
374      so that the demonstration program is easily available in environments where      so that the demonstration program is easily available in environments where
375      PCRE has not been installed from source.      PCRE has not been installed from source.
376    
377  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,
378      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
379      library.      library.
380    
381  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.
382      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
383      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
384      these options useful.      these options useful.
385    
386  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
387      value for nmatch with a NULL value for pmatch, the value of      value for nmatch with a NULL value for pmatch, the value of
388      nmatch is forced to zero.      nmatch is forced to zero.
389    
390  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
391      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
392      RunTest, and also checks for the -b option.      RunTest, and also checks for the -b option.
393    
394  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
395      interposed, within parentheses, between a forward reference to a named      interposed, within parentheses, between a forward reference to a named
396      subpattern and the definition of the subpattern, compilation crashed with      subpattern and the definition of the subpattern, compilation crashed with
397      an internal error, complaining that it could not find the referenced      an internal error, complaining that it could not find the referenced
398      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
399      [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
400      over the character class, thus treating the ] as data rather than      over the character class, thus treating the ] as data rather than
401      terminating the class. This meant it could skip too much.]      terminating the class. This meant it could skip too much.]
402    
403  20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the  20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
404      /g option in pcretest when the pattern contains \K, which makes it possible      /g option in pcretest when the pattern contains \K, which makes it possible
405      to have an empty string match not at the start, even when the pattern is      to have an empty string match not at the start, even when the pattern is
406      anchored. Updated pcretest and pcredemo to use this option.      anchored. Updated pcretest and pcredemo to use this option.
407    
408  21. If the maximum number of capturing subpatterns in a recursion was greater  21. If the maximum number of capturing subpatterns in a recursion was greater
409      than the maximum at the outer level, the higher number was returned, but      than the maximum at the outer level, the higher number was returned, but
410      with unset values at the outer level. The correct (outer level) value is      with unset values at the outer level. The correct (outer level) value is
411      now given.      now given.
412    
413  22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of  22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
414      PCRE did not set those parentheses (unlike Perl). I have now found a way to      PCRE did not set those parentheses (unlike Perl). I have now found a way to
415      make it do so. The string so far is captured, making this feature      make it do so. The string so far is captured, making this feature
416      compatible with Perl.      compatible with Perl.
417    
418  23. The tests have been re-organized, adding tests 11 and 12, to make it  23. The tests have been re-organized, adding tests 11 and 12, to make it
419      possible to check the Perl 5.10 features against Perl 5.10.      possible to check the Perl 5.10 features against Perl 5.10.
420    
421  24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine  24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
422      pattern matches a fixed length string. PCRE did not allow this; now it      pattern matches a fixed length string. PCRE did not allow this; now it
423      does. Neither allows recursion.      does. Neither allows recursion.
424    
425    25. I finally figured out how to implement a request to provide the minimum
426        length of subject string that was needed in order to match a given pattern.
427        (It was back references and recursion that I had previously got hung up
428        on.) This code has now been added to pcre_study(); it finds a lower bound
429        to the length of subject needed. It is not necessarily the greatest lower
430        bound, but using it to avoid searching strings that are too short does give
431        some useful speed-ups. The value is available to calling programs via
432        pcre_fullinfo().
433    
434    26. While implementing 25, I discovered to my embarrassment that pcretest had
435        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
436        study optimizations had never been tested with that matching function.
437        Oops. What is worse, even when it was passed study data, there was a bug in
438        pcre_dfa_exec() that meant it never actually used it. Double oops. There
439        were also very few tests of studied patterns with pcre_dfa_exec().
440    
441    27. If (?| is used to create subpatterns with duplicate numbers, they are now
442        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
443        on the other side of the coin, they are no longer allowed to have different
444        names, because these cannot be distinguished in PCRE, and this has caused
445        confusion. (This is a difference from Perl.)
446    
447    28. When duplicate subpattern names are present (necessarily with different
448        numbers, as required by 27 above), and a test is made by name in a
449        conditional pattern, either for a subpattern having been matched, or for
450        recursion in such a pattern, all the associated numbered subpatterns are
451        tested, and the overall condition is true if the condition is true for any
452        one of them. This is the way Perl works, and is also more like the way
453        testing by number works.
454    
455    
456  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
457  ---------------------  ---------------------

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