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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 342 by ph10, Sun Apr 20 17:10:13 2008 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.7 05-Mar-08
5    ---------------------
7    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
8        a string to a long long, pretend we don't even have a long long." This is
9        done by checking for the strtoq, strtoll, and _strtoi64 functions.
11    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
12        pre-7.6 versions, which defined a global no_arg variable instead of putting
13        it in the RE class. (See also #8 below.)
15    3.  Remove a line of dead code, identified by coverity and reported by Nuno
16        Lopes.
18    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
20        (1) The include/exclude patterns were being applied to the whole pathnames
21            of files, instead of just to the final components.
23        (2) If there was more than one level of directory, the subdirectories were
24            skipped unless they satisfied the include/exclude conditions. This is
25            inconsistent with GNU grep (and could even be seen as contrary to the
26            pcregrep specification - which I improved to make it absolutely clear).
27            The action now is always to scan all levels of directory, and just
28            apply the include/exclude patterns to regular files.
30    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
31        --exclude_dir in the tests to avoid scanning .svn directories.
33    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
34        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
35        doesn't support NULs in patterns.
37    7.  Added some missing "const"s to declarations of static tables in
38        pcre_compile.c and pcre_dfa_exec.c.
40    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
41        caused by fix #2  above. (Subsequently also a second patch to fix the
42        first patch. And a third patch - this was a messy problem.)
44    9.  Applied Craig's patch to remove the use of push_back().
46    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
47        matching function regexec().
49    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
50        which, however, unlike Perl's \g{...}, are subroutine calls, not back
51        references. PCRE supports relative numbers with this syntax (I don't think
52        Oniguruma does).
54    12. Previously, a group with a zero repeat such as (...){0} was completely
55        omitted from the compiled regex. However, this means that if the group
56        was called as a subroutine from elsewhere in the pattern, things went wrong
57        (an internal error was given). Such groups are now left in the compiled
58        pattern, with a new opcode that causes them to be skipped at execution
59        time.
61    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
62        to the way PCRE behaves:
64        (a) A lone ] character is dis-allowed (Perl treats it as data).
66        (b) A back reference to an unmatched subpattern matches an empty string
67            (Perl fails the current match path).
69        (c) A data ] in a character class must be notated as \] because if the
70            first data character in a class is ], it defines an empty class. (In
71            Perl it is not possible to have an empty class.) The empty class []
72            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
73            The negative empty class [^] matches any one character, independently
74            of the DOTALL setting.
76    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
77        non-existent subpattern following a character class starting with ']' and
78        containing () gave an internal compiling error instead of "reference to
79        non-existent subpattern". Fortunately, when the pattern did exist, the
80        compiled code was correct. (When scanning forwards to check for the
81        existencd of the subpattern, it was treating the data ']' as terminating
82        the class, so got the count wrong. When actually compiling, the reference
83        was subsequently set up correctly.)
85    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
86        it was being rejected as not supported by pcre_dfa_exec(), even though
87        other assertions are supported. I have made pcre_dfa_exec() support
88        (*FAIL).
90    16. The implementation of 13c above involved the invention of a new opcode,
91        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
92        cannot be changed at match time, I realized I could make a small
93        improvement to matching performance by compiling OP_ALLANY instead of
94        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
95        on the OP_ANY path.
98    Version 7.6 28-Jan-08
99    ---------------------
101    1.  A character class containing a very large number of characters with
102        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
103        overflow.
105    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
106        HAVE_LONG_LONG is not defined.
108    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
109        bring them up to date and include new features. This patch includes:
111        - Fixed PH's badly added libz and libbz2 support.
112        - Fixed a problem with static linking.
113        - Added pcredemo. [But later removed - see 7 below.]
114        - Fixed dftables problem and added an option.
115        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
116            HAVE_LONG_LONG.
117        - Added readline support for pcretest.
118        - Added an listing of the option settings after cmake has run.
120    4.  A user submitted a patch to Makefile that makes it easy to create
121        "pcre.dll" under mingw when using Configure/Make. I added stuff to
122        Makefile.am that cause it to include this special target, without
123        affecting anything else. Note that the same mingw target plus all
124        the other distribution libraries and programs are now supported
125        when configuring with CMake (see 6 below) instead of with
126        Configure/Make.
128    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
129        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
130        exported in the Windows port". It has not yet been confirmed that the patch
131        solves the problem, but it does no harm.
133    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
134        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
135        with CMake, and also correct the comment about stack recursion.
137    7.  Remove the automatic building of pcredemo from the ./configure system and
138        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
139        of a program that users should build themselves after PCRE is installed, so
140        building it automatically is not really right. What is more, it gave
141        trouble in some build environments.
143    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
146    Version 7.5 10-Jan-08
147    ---------------------
149    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
150        values in parens when parsing an RE using the C++ wrapper."
152    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
153        Characters greater than 255 were excluded from the class instead of being
154        included.
156    3.  The same bug as (2) above applied to negated POSIX classes such as
157        [:^space:].
159    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
160        defined or documented. It seems to have been a typo for PCRE_STATIC, so
161        I have changed it.
163    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
164        first named subpattern) and a construct such as (?&a) would reference the
165        first named subpattern whose name started with "a" (in other words, the
166        length check was missing). Both these problems are fixed. "Subpattern name
167        expected" is now given for (?&) (a zero-length name), and this patch also
168        makes it give the same error for \k'' (previously it complained that that
169        was a reference to a non-existent subpattern).
171    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
172        this is right because (?- can be followed by option settings as well as by
173        digits. I have, however, made the messages clearer.
175    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
176        than the number used in the conditional) now cause a compile-time error.
177        This is actually not compatible with Perl, which accepts such patterns, but
178        treats the conditional as always being FALSE (as PCRE used to), but it
179        seems to me that giving a diagnostic is better.
181    8.  Change "alphameric" to the more common word "alphanumeric" in comments
182        and messages.
184    9.  Fix two occurrences of "backslash" in comments that should have been
185        "backspace".
187    10. Remove two redundant lines of code that can never be obeyed (their function
188        was moved elsewhere).
190    11. The program that makes PCRE's Unicode character property table had a bug
191        which caused it to generate incorrect table entries for sequences of
192        characters that have the same character type, but are in different scripts.
193        It amalgamated them into a single range, with the script of the first of
194        them. In other words, some characters were in the wrong script. There were
195        thirteen such cases, affecting characters in the following ranges:
197          U+002b0 - U+002c1
198          U+0060c - U+0060d
199          U+0061e - U+00612
200          U+0064b - U+0065e
201          U+0074d - U+0076d
202          U+01800 - U+01805
203          U+01d00 - U+01d77
204          U+01d9b - U+01dbf
205          U+0200b - U+0200f
206          U+030fc - U+030fe
207          U+03260 - U+0327f
208          U+0fb46 - U+0fbb1
209          U+10450 - U+1049d
211    12. The -o option (show only the matching part of a line) for pcregrep was not
212        compatible with GNU grep in that, if there was more than one match in a
213        line, it showed only the first of them. It now behaves in the same way as
214        GNU grep.
216    13. If the -o and -v options were combined for pcregrep, it printed a blank
217        line for every non-matching line. GNU grep prints nothing, and pcregrep now
218        does the same. The return code can be used to tell if there were any
219        non-matching lines.
221    14. Added --file-offsets and --line-offsets to pcregrep.
223    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
224        infinitely looping recursion. The bug was that positive lookaheads were not
225        being skipped when checking for a possible empty match (negative lookaheads
226        and both kinds of lookbehind were skipped).
228    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
229        inclusion of <windows.h> to before rather than after the definition of
230        INVALID_FILE_ATTRIBUTES (patch from David Byron).
232    17. Specifying a possessive quantifier with a specific limit for a Unicode
233        character property caused pcre_compile() to compile bad code, which led at
234        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
235        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
236        caused the error; without that there was no problem.
238    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
240    19. Added --enable-pcretest-libreadline.
242    20. In pcrecpp.cc, the variable 'count' was incremented twice in
243        RE::GlobalReplace(). As a result, the number of replacements returned was
244        double what it should be. I removed one of the increments, but Craig sent a
245        later patch that removed the other one (the right fix) and added unit tests
246        that check the return values (which was not done before).
248    21. Several CMake things:
250        (1) Arranged that, when cmake is used on Unix, the libraries end up with
251            the names libpcre and libpcreposix, not just pcre and pcreposix.
253        (2) The above change means that pcretest and pcregrep are now correctly
254            linked with the newly-built libraries, not previously installed ones.
258    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
259        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
260        UTF-8 newline character). The key issue is that the pattern starts .*;
261        this means that the match must be either at the beginning, or after a
262        newline. The bug was in the code for advancing after a failed match and
263        checking that the new position followed a newline. It was not taking
264        account of UTF-8 characters correctly.
266    23. PCRE was behaving differently from Perl in the way it recognized POSIX
267        character classes. PCRE was not treating the sequence [:...:] as a
268        character class unless the ... were all letters. Perl, however, seems to
269        allow any characters between [: and :], though of course it rejects as
270        unknown any "names" that contain non-letters, because all the known class
271        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
272        for example, whereas PCRE did not - it did not recognize a POSIX character
273        class. This seemed a bit dangerous, so the code has been changed to be
274        closer to Perl. The behaviour is not identical to Perl, because PCRE will
275        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
276        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
277        Perl does, and where it didn't before.
279    24. Rewrite so as to remove the single use of %n from pcregrep because in some
280        Windows environments %n is disabled by default.
283    Version 7.4 21-Sep-07
284    ---------------------
286    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
287        means that a class such as [\s] counted as "explicit reference to CR or
288        LF". That isn't really right - the whole point of the change was to try to
289        help when there was an actual mention of one of the two characters. So now
290        the change happens only if \r or \n (or a literal CR or LF) character is
291        encountered.
293    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
294        of both had grown to the point where there were only 3 bits left.
295        Fortunately, there was spare space in the data structure, and so I have
296        moved the internal flags into a new 16-bit field to free up more option
297        bits.
299    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
300        but did not set the internal JCHANGED flag - either of these is enough to
301        control the way the "get" function works - but the PCRE_INFO_JCHANGED
302        facility is supposed to tell if (?J) was ever used, so now (?J) at the
303        start sets both bits.
305    4.  Added options (at build time, compile time, exec time) to change \R from
306        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
308    5.  doc/pcresyntax.html was missing from the distribution.
310    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
311        compatibility, even though it is no longer used.
313    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
314        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
315        windows.h file is present (where different names are used). [This was
316        reversed later after testing - see 16 below.]
318    8.  Changed all #include <config.h> to #include "config.h". There were also
319        some further <pcre.h> cases that I changed to "pcre.h".
321    9.  When pcregrep was used with the --colour option, it missed the line ending
322        sequence off the lines that it output.
324    10. It was pointed out to me that arrays of string pointers cause lots of
325        relocations when a shared library is dynamically loaded. A technique of
326        using a single long string with a table of offsets can drastically reduce
327        these. I have refactored PCRE in four places to do this. The result is
328        dramatic:
330          Originally:                          290
331          After changing UCP table:            187
332          After changing error message table:   43
333          After changing table of "verbs"       36
334          After changing table of Posix names   22
336        Thanks to the folks working on Gregex for glib for this insight.
338    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
339        unicode-properties was also set.
341    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
343    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
344        checked only for CRLF.
346    14. Added casts to pcretest.c to avoid compiler warnings.
348    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
350    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
351        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
352        entirely. This removes changes made in 7 above.
354    17. The CMake files have been updated, and there is now more information about
355        building with CMake in the NON-UNIX-USE document.
358    Version 7.3 28-Aug-07
359    ---------------------
361     1. In the rejigging of the build system that eventually resulted in 7.1, the
362        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
363        brackets there is not right, since it causes compilers to look for an
364        installed pcre.h, not the version that is in the source that is being
365        compiled (which of course may be different). I have changed it back to:
367          #include "pcre.h"
369        I have a vague recollection that the change was concerned with compiling in
370        different directories, but in the new build system, that is taken care of
371        by the VPATH setting the Makefile.
373     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
374        when the subject happened to end in the byte 0x85 (e.g. if the last
375        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
376        characters but of course it shouldn't be taken as a newline when it is part
377        of another character. The bug was that, for an unlimited repeat of . in
378        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
379        characters when looking for a newline.
381     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
383     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
384        in debug output.
386     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
387        long printing in the pcrecpp unittest when running under MinGW.
389     6. ESC_K was left out of the EBCDIC table.
391     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
392        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
393        limit also applies to "virtual nesting" when a pattern is recursive, and in
394        this case 1000 isn't so big. I have been able to remove this limit at the
395        expense of backing off one optimization in certain circumstances. Normally,
396        when pcre_exec() would call its internal match() function recursively and
397        immediately return the result unconditionally, it uses a "tail recursion"
398        feature to save stack. However, when a subpattern that can match an empty
399        string has an unlimited repetition quantifier, it no longer makes this
400        optimization. That gives it a stack frame in which to save the data for
401        checking that an empty string has been matched. Previously this was taken
402        from the 1000-entry workspace that had been reserved. So now there is no
403        explicit limit, but more stack is used.
405     8. Applied Daniel's patches to solve problems with the import/export magic
406        syntax that is required for Windows, and which was going wrong for the
407        pcreposix and pcrecpp parts of the library. These were overlooked when this
408        problem was solved for the main library.
410     9. There were some crude static tests to avoid integer overflow when computing
411        the size of patterns that contain repeated groups with explicit upper
412        limits. As the maximum quantifier is 65535, the maximum group length was
413        set at 30,000 so that the product of these two numbers did not overflow a
414        32-bit integer. However, it turns out that people want to use groups that
415        are longer than 30,000 bytes (though not repeat them that many times).
416        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
417        made it possible to implement the integer overflow checks in a much more
418        dynamic way, which I have now done. The artificial limitation on group
419        length has been removed - we now have only the limit on the total length of
420        the compiled pattern, which depends on the LINK_SIZE setting.
422    10. Fixed a bug in the documentation for get/copy named substring when
423        duplicate names are permitted. If none of the named substrings are set, the
424        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
425        empty string.
427    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
428        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
429        because the ] is interpreted as the first data character and the
430        terminating ] is not found. PCRE has been made compatible with Perl in this
431        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
432        cause memory overwriting.
434    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
435        string has been matched (to stop an infinite loop). It was not recognizing
436        a conditional subpattern that could match an empty string if that
437        subpattern was within another subpattern. For example, it looped when
438        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
439        condition was not nested. This bug has been fixed.
441    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
442        past the start of the subject in the presence of bytes with the top bit
443        set, for example "\x8aBCD".
445    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
446        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
448    14. Optimized (?!) to (*FAIL).
450    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
451        This restricts code points to be within the range 0 to 0x10FFFF, excluding
452        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
453        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
454        does: it's just the validity check that is more restrictive.
456    16. Inserted checks for integer overflows during escape sequence (backslash)
457        processing, and also fixed erroneous offset values for syntax errors during
458        backslash processing.
460    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
461        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
463    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
464        caused an overrun.
466    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
467        something other than just ASCII characters) inside a group that had an
468        unlimited repeat caused a loop at compile time (while checking to see
469        whether the group could match an empty string).
471    20. Debugging a pattern containing \p or \P could cause a crash. For example,
472        [\P{Any}] did so. (Error in the code for printing property names.)
474    21. An orphan \E inside a character class could cause a crash.
476    22. A repeated capturing bracket such as (A)? could cause a wild memory
477        reference during compilation.
479    23. There are several functions in pcre_compile() that scan along a compiled
480        expression for various reasons (e.g. to see if it's fixed length for look
481        behind). There were bugs in these functions when a repeated \p or \P was
482        present in the pattern. These operators have additional parameters compared
483        with \d, etc, and these were not being taken into account when moving along
484        the compiled data. Specifically:
486        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
487            length.
489        (b) An item such as \pL+ within a repeated group could cause crashes or
490            loops.
492        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
493            "reference to non-existent subpattern" error.
495        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
497    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
498        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
500    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
502    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
503        character were causing crashes (broken optimization).
505    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
506        \p or \P) caused a compile-time loop.
508    28. More problems have arisen in unanchored patterns when CRLF is a valid line
509        break. For example, the unstudied pattern [\r\n]A does not match the string
510        "\r\nA" because change 7.0/46 below moves the current point on by two
511        characters after failing to match at the start. However, the pattern \nA
512        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
513        the same is true. There doesn't seem any very clean way out of this, but
514        what I have chosen to do makes the common cases work: PCRE now takes note
515        of whether there can be an explicit match for \r or \n anywhere in the
516        pattern, and if so, 7.0/46 no longer applies. As part of this change,
517        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
518        pattern has explicit CR or LF references.
520    29. Added (*CR) etc for changing newline setting at start of pattern.
523    Version 7.2 19-Jun-07
524    ---------------------
526     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
527        which is apparently normally available under Windows.
529     2. Re-jig the pcregrep tests with different newline settings in an attempt
530        to make them independent of the local environment's newline setting.
532     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
534     4. Some of the "internals" tests were previously cut out when the link size
535        was not 2, because the output contained actual offsets. The recent new
536        "Z" feature of pcretest means that these can be cut out, making the tests
537        usable with all link sizes.
539     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
540        stack recursion. This gives a massive performance boost under BSD, but just
541        a small improvement under Linux. However, it saves one field in the frame
542        in all cases.
544     6. Added more features from the forthcoming Perl 5.10:
546        (a) (?-n) (where n is a string of digits) is a relative subroutine or
547            recursion call. It refers to the nth most recently opened parentheses.
549        (b) (?+n) is also a relative subroutine call; it refers to the nth next
550            to be opened parentheses.
552        (c) Conditions that refer to capturing parentheses can be specified
553            relatively, for example, (?(-2)... or (?(+3)...
555        (d) \K resets the start of the current match so that everything before
556            is not part of it.
558        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
560        (f) \g{name} is another synonym - part of Perl 5.10's unification of
561            reference syntax.
563        (g) (?| introduces a group in which the numbering of parentheses in each
564            alternative starts with the same number.
566        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
568     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
571     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
572        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
573        for detecting groups that can match an empty string.
575     9. A pattern with a very large number of alternatives (more than several
576        hundred) was running out of internal workspace during the pre-compile
577        phase, where pcre_compile() figures out how much memory will be needed. A
578        bit of new cunning has reduced the workspace needed for groups with
579        alternatives. The 1000-alternative test pattern now uses 12 bytes of
580        workspace instead of running out of the 4096 that are available.
582    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
584    11. Applied patch from Google to remove an optimization that didn't quite work.
585        The report of the bug said:
587          pcrecpp::RE("a*").FullMatch("aaa") matches, while
588          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
589          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
591    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
592        it matched the wrong number of bytes.
595    Version 7.1 24-Apr-07
596    ---------------------
598     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
599        that is more "standard", making use of automake and other Autotools. There
600        is some re-arrangement of the files and adjustment of comments consequent
601        on this.
603     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
604        for recursive directory scanning broke on some systems because the files
605        are not scanned in any specific order and on different systems the order
606        was different. A call to "sort" has been inserted into RunGrepTest for the
607        approprate test as a short-term fix. In the longer term there may be an
608        alternative.
610     3. I had an email from Eric Raymond about problems translating some of PCRE's
611        man pages to HTML (despite the fact that I distribute HTML pages, some
612        people do their own conversions for various reasons). The problems
613        concerned the use of low-level troff macros .br and .in. I have therefore
614        removed all such uses from the man pages (some were redundant, some could
615        be replaced by .nf/.fi pairs). The 132html script that I use to generate
616        HTML has been updated to handle .nf/.fi and to complain if it encounters
617        .br or .in.
619     4. Updated comments in configure.ac that get placed in config.h.in and also
620        arranged for config.h to be included in the distribution, with the name
621        config.h.generic, for the benefit of those who have to compile without
622        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
624     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
625        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
626        makevp.bat for the current PCRE, using the additional files
627        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
629     6. A Windows user reported a minor discrepancy with test 2, which turned out
630        to be caused by a trailing space on an input line that had got lost in his
631        copy. The trailing space was an accident, so I've just removed it.
633     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
634        that is needed.
636     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
637        as "const" (a) because they are and (b) because it helps the PHP
638        maintainers who have recently made a script to detect big data structures
639        in the php code that should be moved to the .rodata section. I remembered
640        to update Builducptable as well, so it won't revert if ucptable.h is ever
641        re-created.
643     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
644        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
645        order to be able to cut out the UTF-8 tables in the latter when UTF-8
646        support is not required. This saves 1.5-2K of code, which is important in
647        some applications.
649        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
650        so as not to refer to the tables, even though these functions will never be
651        called when UTF-8 support is disabled. Otherwise there are problems with a
652        shared library.
654    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
656        (a) It was defining its arguments as char * instead of void *.
658        (b) It was assuming that all moves were upwards in memory; this was true
659            a long time ago when I wrote it, but is no longer the case.
661        The emulated memove() is provided for those environments that have neither
662        memmove() nor bcopy(). I didn't think anyone used it these days, but that
663        is clearly not the case, as these two bugs were recently reported.
665    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
666        and Detrail to create the HTML documentation, the .txt form of the man
667        pages, and it removes trailing spaces from listed files. It also creates
668        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
669        case, it wraps all the #defines with #ifndefs. This script should be run
670        before "make dist".
672    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
673        with Unicode property support.
675        (a) For a maximizing quantifier, if the two different cases of the
676            character were of different lengths in their UTF-8 codings (there are
677            some cases like this - I found 11), and the matching function had to
678            back up over a mixture of the two cases, it incorrectly assumed they
679            were both the same length.
681        (b) When PCRE was configured to use the heap rather than the stack for
682            recursion during matching, it was not correctly preserving the data for
683            the other case of a UTF-8 character when checking ahead for a match
684            while processing a minimizing repeat. If the check also involved
685            matching a wide character, but failed, corruption could cause an
686            erroneous result when trying to check for a repeat of the original
687            character.
689    13. Some tidying changes to the testing mechanism:
691        (a) The RunTest script now detects the internal link size and whether there
692            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
693            values substituted by "configure". (The RunGrepTest script already did
694            this for UTF-8.) The configure.ac script no longer substitutes the
695            relevant variables.
697        (b) The debugging options /B and /D in pcretest show the compiled bytecode
698            with length and offset values. This means that the output is different
699            for different internal link sizes. Test 2 is skipped for link sizes
700            other than 2 because of this, bypassing the problem. Unfortunately,
701            there was also a test in test 3 (the locale tests) that used /B and
702            failed for link sizes other than 2. Rather than cut the whole test out,
703            I have added a new /Z option to pcretest that replaces the length and
704            offset values with spaces. This is now used to make test 3 independent
705            of link size. (Test 2 will be tidied up later.)
707    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
708        segmentation fault instead of returning the appropriate error message.
710    15. In multiline mode when the newline sequence was set to "any", the pattern
711        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
712        This doesn't seem right; it now treats the CRLF combination as the line
713        ending, and so does not match in that case. It's only a pattern such as ^$
714        that would hit this one: something like ^ABC$ would have failed after \r
715        and then tried again after \r\n.
717    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
718        in an attempt to make files that differ only in their line terminators
719        compare equal. This works on Linux.
721    17. Under certain error circumstances pcregrep might try to free random memory
722        as it exited. This is now fixed, thanks to valgrind.
724    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
725        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
726        was because its rules for how to advance for /g after matching an empty
727        string at the end of a line did not allow for this case. They now check for
728        it specially.
730    20. pcretest is supposed to handle patterns and data of any length, by
731        extending its buffers when necessary. It was getting this wrong when the
732        buffer for a data line had to be extended.
734    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
735        CRLF as a newline sequence.
737    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
738        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
739        I have nevertheless tidied it up.
741    23. Added some casts to kill warnings from HP-UX ia64 compiler.
743    24. Added a man page for pcre-config.
746    Version 7.0 19-Dec-06
747    ---------------------
749     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
750        moving to gcc 4.1.1.
752     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
753        sys/time.h, which is documented as needed for this function. It doesn't
754        seem to matter on Linux, but it showed up on some releases of OS X.
756     3. It seems that there are systems where bytes whose values are greater than
757        127 match isprint() in the "C" locale. The "C" locale should be the
758        default when a C program starts up. In most systems, only ASCII printing
759        characters match isprint(). This difference caused the output from pcretest
760        to vary, making some of the tests fail. I have changed pcretest so that:
762        (a) When it is outputting text in the compiled version of a pattern, bytes
763            other than 32-126 are always shown as hex escapes.
765        (b) When it is outputting text that is a matched part of a subject string,
766            it does the same, unless a different locale has been set for the match
767            (using the /L modifier). In this case, it uses isprint() to decide.
769     4. Fixed a major bug that caused incorrect computation of the amount of memory
770        required for a compiled pattern when options that changed within the
771        pattern affected the logic of the preliminary scan that determines the
772        length. The relevant options are -x, and -i in UTF-8 mode. The result was
773        that the computed length was too small. The symptoms of this bug were
774        either the PCRE error "internal error: code overflow" from pcre_compile(),
775        or a glibc crash with a message such as "pcretest: free(): invalid next
776        size (fast)". Examples of patterns that provoked this bug (shown in
777        pcretest format) are:
779          /(?-x: )/x
780          /(?x)(?-x: \s*#\s*)/
781          /((?i)[\x{c0}])/8
782          /(?i:[\x{c0}])/8
784        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
785        is now done differently.
787     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
788        wrapper classes; (b) implement a new function in the C++ scanner that is
789        more efficient than the old way of doing things because it avoids levels of
790        recursion in the regex matching; (c) add a paragraph to the documentation
791        for the FullMatch() function.
793     6. The escape sequence \n was being treated as whatever was defined as
794        "newline". Not only was this contrary to the documentation, which states
795        that \n is character 10 (hex 0A), but it also went horribly wrong when
796        "newline" was defined as CRLF. This has been fixed.
798     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
799        was being set to -1 for the "end of line" case (supposedly a value that no
800        character can have). Though this value is never used (the check for end of
801        line is "zero bytes in current character"), it caused compiler complaints.
802        I've changed it to 0xffffffff.
804     8. In pcre_version.c, the version string was being built by a sequence of
805        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
806        string (as it is for production releases) called a macro with an empty
807        argument. The C standard says the result of this is undefined. The gcc
808        compiler treats it as an empty string (which was what was wanted) but it is
809        reported that Visual C gives an error. The source has been hacked around to
810        avoid this problem.
812     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
813        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
814        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
815        of them did).
817    10. Originally, pcretest opened its input and output without "b"; then I was
818        told that "b" was needed in some environments, so it was added for release
819        5.0 to both the input and output. (It makes no difference on Unix-like
820        systems.) Later I was told that it is wrong for the input on Windows. I've
821        now abstracted the modes into two macros, to make it easier to fiddle with
822        them, and removed "b" from the input mode under Windows.
824    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
826    12. Added -help and --help to pcretest as an official way of being reminded
827        of the options.
829    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
830        and pcrecpp.cc because they annoy compilers at high warning levels.
832    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
834    15. Fixed an occurrence of == in configure.ac that should have been = (shell
835        scripts are not C programs :-) and which was not noticed because it works
836        on Linux.
838    16. pcretest is supposed to handle any length of pattern and data line (as one
839        line or as a continued sequence of lines) by extending its input buffer if
840        necessary. This feature was broken for very long pattern lines, leading to
841        a string of junk being passed to pcre_compile() if the pattern was longer
842        than about 50K.
844    17. I have done a major re-factoring of the way pcre_compile() computes the
845        amount of memory needed for a compiled pattern. Previously, there was code
846        that made a preliminary scan of the pattern in order to do this. That was
847        OK when PCRE was new, but as the facilities have expanded, it has become
848        harder and harder to keep it in step with the real compile phase, and there
849        have been a number of bugs (see for example, 4 above). I have now found a
850        cunning way of running the real compile function in a "fake" mode that
851        enables it to compute how much memory it would need, while actually only
852        ever using a few hundred bytes of working memory and without too many
853        tests of the mode. This should make future maintenance and development
854        easier. A side effect of this work is that the limit of 200 on the nesting
855        depth of parentheses has been removed (though this was never a serious
856        limitation, I suspect). However, there is a downside: pcre_compile() now
857        runs more slowly than before (30% or more, depending on the pattern). I
858        hope this isn't a big issue. There is no effect on runtime performance.
860    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
861        newline (only possible for the last line of a file) and it was a
862        pattern that set a locale (followed by /Lsomething), pcretest crashed.
864    19. Added additional timing features to pcretest. (1) The -tm option now times
865        matching only, not compiling. (2) Both -t and -tm can be followed, as a
866        separate command line item, by a number that specifies the number of
867        repeats to use when timing. The default is 50000; this gives better
868        precision, but takes uncomfortably long for very large patterns.
870    20. Extended pcre_study() to be more clever in cases where a branch of a
871        subpattern has no definite first character. For example, (a*|b*)[cd] would
872        previously give no result from pcre_study(). Now it recognizes that the
873        first character must be a, b, c, or d.
875    21. There was an incorrect error "recursive call could loop indefinitely" if
876        a subpattern (or the entire pattern) that was being tested for matching an
877        empty string contained only one non-empty item after a nested subpattern.
878        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
879        incorrectly, because the \d was being skipped in the check.
881    22. The pcretest program now has a new pattern option /B and a command line
882        option -b, which is equivalent to adding /B to every pattern. This causes
883        it to show the compiled bytecode, without the additional information that
884        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
885        is the same as /B/I).
887    23. A new optimization is now able automatically to treat some sequences such
888        as a*b as a*+b. More specifically, if something simple (such as a character
889        or a simple class like \d) has an unlimited quantifier, and is followed by
890        something that cannot possibly match the quantified thing, the quantifier
891        is automatically "possessified".
893    24. A recursive reference to a subpattern whose number was greater than 39
894        went wrong under certain circumstances in UTF-8 mode. This bug could also
895        have affected the operation of pcre_study().
897    25. Realized that a little bit of performance could be had by replacing
898        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
900    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
902    27. Possessive quantifiers such as a++ were previously implemented by turning
903        them into atomic groups such as ($>a+). Now they have their own opcodes,
904        which improves performance. This includes the automatically created ones
905        from 23 above.
907    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
908        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
909        the first matched character to be a colon. This applied both to named and
910        numbered groups.
912    29. The ucpinternal.h header file was missing its idempotency #ifdef.
914    30. I was sent a "project" file called libpcre.a.dev which I understand makes
915        building PCRE on Windows easier, so I have included it in the distribution.
917    31. There is now a check in pcretest against a ridiculously large number being
918        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
919        loop, the loop is abandoned.
921    32. Forward references to subpatterns in conditions such as (?(2)...) where
922        subpattern 2 is defined later cause pcre_compile() to search forwards in
923        the pattern for the relevant set of parentheses. This search went wrong
924        when there were unescaped parentheses in a character class, parentheses
925        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
927    33. "Subroutine" calls and backreferences were previously restricted to
928        referencing subpatterns earlier in the regex. This restriction has now
929        been removed.
931    34. Added a number of extra features that are going to be in Perl 5.10. On the
932        whole, these are just syntactic alternatives for features that PCRE had
933        previously implemented using the Python syntax or my own invention. The
934        other formats are all retained for compatibility.
936        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
937            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
938            also .NET compatible.
940        (b) A recursion or subroutine call to a named group can now be defined as
941            (?&name) as well as (?P>name).
943        (c) A backreference to a named group can now be defined as \k<name> or
944            \k'name' as well as (?P=name). The new forms, as well as being in Perl
945            5.10, are also .NET compatible.
947        (d) A conditional reference to a named group can now use the syntax
948            (?(<name>) or (?('name') as well as (?(name).
950        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
951            groups (named and numbered) that are never evaluated inline, but can be
952            called as "subroutines" from elsewhere. In effect, the DEFINE condition
953            is always false. There may be only one alternative in such a group.
955        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
956            as the simple (?(R). The condition is true only if the most recent
957            recursion is that of the given number or name. It does not search out
958            through the entire recursion stack.
960        (g) The escape \gN or \g{N} has been added, where N is a positive or
961            negative number, specifying an absolute or relative reference.
963    35. Tidied to get rid of some further signed/unsigned compiler warnings and
964        some "unreachable code" warnings.
966    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
967        things, this adds five new scripts.
969    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
970        There were also incompatibilities regarding the handling of \Q..\E inside
971        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
972        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
974    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
975        matches an empty string, and forcibly breaks the loop. There were bugs in
976        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
977        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
978        separate and independent bugs (that affected different cases) have been
979        fixed.
981    39. Refactored the code to abolish the use of different opcodes for small
982        capturing bracket numbers. This is a tidy that I avoided doing when I
983        removed the limit on the number of capturing brackets for 3.5 back in 2001.
984        The new approach is not only tidier, it makes it possible to reduce the
985        memory needed to fix the previous bug (38).
987    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
988        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
989        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
990        mode.
992    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
993        report.
995    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
996        copy construction and assignment in the C++ wrapper.
998    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
999        couple of bugs that could have given wrong results in the "--newline=crlf"
1000        case.
1002    44. Added a number of casts and did some reorganization of signed/unsigned int
1003        variables following suggestions from Dair Grant. Also renamed the variable
1004        "this" as "item" because it is a C++ keyword.
1006    45. Arranged for dftables to add
1008          #include "pcre_internal.h"
1010        to pcre_chartables.c because without it, gcc 4.x may remove the array
1011        definition from the final binary if PCRE is built into a static library and
1012        dead code stripping is activated.
1014    46. For an unanchored pattern, if a match attempt fails at the start of a
1015        newline sequence, and the newline setting is CRLF or ANY, and the next two
1016        characters are CRLF, advance by two characters instead of one.
1019  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
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