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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 8.0 02 Jul-08
5    ---------------------
7    1.  Replaced UCP searching code with optimized version as implemented for Ad
8        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
9        stage table and inline lookup instead of a function, giving speed ups of 2
10        to 5 times on some simple patterns that I tested. Permission was given to
11        distribute the MultiStage2.py script that generates the tables (it's not in
12        the tarball, but is in the Subversion repository).
14    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
15        scripts.
17    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
18        a group with a zero qualifier. The result of the study could be incorrect,
19        or the function might crash, depending on the pattern.
21    4.  Caseless matching was not working for non-ASCII characters in back
22        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
23        It now works when Unicode Property Support is available.
25    5.  In pcretest, an escape such as \x{de} in the data was always generating
26        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
27        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
28        truncation.
30    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
32    7.  Added two (int) casts to pcregrep when printing the difference of two
33        pointers, in case they are 64-bit values.
36    Version 7.7 07-May-08
37    ---------------------
39    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
40        a string to a long long, pretend we don't even have a long long." This is
41        done by checking for the strtoq, strtoll, and _strtoi64 functions.
43    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
44        pre-7.6 versions, which defined a global no_arg variable instead of putting
45        it in the RE class. (See also #8 below.)
47    3.  Remove a line of dead code, identified by coverity and reported by Nuno
48        Lopes.
50    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
52        (1) The include/exclude patterns were being applied to the whole pathnames
53            of files, instead of just to the final components.
55        (2) If there was more than one level of directory, the subdirectories were
56            skipped unless they satisfied the include/exclude conditions. This is
57            inconsistent with GNU grep (and could even be seen as contrary to the
58            pcregrep specification - which I improved to make it absolutely clear).
59            The action now is always to scan all levels of directory, and just
60            apply the include/exclude patterns to regular files.
62    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
63        --exclude_dir in the tests to avoid scanning .svn directories.
65    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
66        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
67        doesn't support NULs in patterns.
69    7.  Added some missing "const"s to declarations of static tables in
70        pcre_compile.c and pcre_dfa_exec.c.
72    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
73        caused by fix #2  above. (Subsequently also a second patch to fix the
74        first patch. And a third patch - this was a messy problem.)
76    9.  Applied Craig's patch to remove the use of push_back().
78    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
79        matching function regexec().
81    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
82        which, however, unlike Perl's \g{...}, are subroutine calls, not back
83        references. PCRE supports relative numbers with this syntax (I don't think
84        Oniguruma does).
86    12. Previously, a group with a zero repeat such as (...){0} was completely
87        omitted from the compiled regex. However, this means that if the group
88        was called as a subroutine from elsewhere in the pattern, things went wrong
89        (an internal error was given). Such groups are now left in the compiled
90        pattern, with a new opcode that causes them to be skipped at execution
91        time.
93    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
94        to the way PCRE behaves:
96        (a) A lone ] character is dis-allowed (Perl treats it as data).
98        (b) A back reference to an unmatched subpattern matches an empty string
99            (Perl fails the current match path).
101        (c) A data ] in a character class must be notated as \] because if the
102            first data character in a class is ], it defines an empty class. (In
103            Perl it is not possible to have an empty class.) The empty class []
104            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
105            The negative empty class [^] matches any one character, independently
106            of the DOTALL setting.
108    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
109        non-existent subpattern following a character class starting with ']' and
110        containing () gave an internal compiling error instead of "reference to
111        non-existent subpattern". Fortunately, when the pattern did exist, the
112        compiled code was correct. (When scanning forwards to check for the
113        existencd of the subpattern, it was treating the data ']' as terminating
114        the class, so got the count wrong. When actually compiling, the reference
115        was subsequently set up correctly.)
117    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
118        it was being rejected as not supported by pcre_dfa_exec(), even though
119        other assertions are supported. I have made pcre_dfa_exec() support
120        (*FAIL).
122    16. The implementation of 13c above involved the invention of a new opcode,
123        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
124        cannot be changed at match time, I realized I could make a small
125        improvement to matching performance by compiling OP_ALLANY instead of
126        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
127        on the OP_ANY path.
129    17. Compiling pcretest on Windows with readline support failed without the
130        following two fixes: (1) Make the unistd.h include conditional on
131        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
133    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
134        ncurses library to be included for pcretest when ReadLine support is
135        requested, but also to allow for it to be overridden. This patch came from
136        Daniel Bergström.
138    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
139        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
140        any errors with the current Unicode tables. Thanks to Peter Kankowski for
141        spotting this.
144    Version 7.6 28-Jan-08
145    ---------------------
147    1.  A character class containing a very large number of characters with
148        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
149        overflow.
151    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
152        HAVE_LONG_LONG is not defined.
154    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
155        bring them up to date and include new features. This patch includes:
157        - Fixed PH's badly added libz and libbz2 support.
158        - Fixed a problem with static linking.
159        - Added pcredemo. [But later removed - see 7 below.]
160        - Fixed dftables problem and added an option.
161        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
162            HAVE_LONG_LONG.
163        - Added readline support for pcretest.
164        - Added an listing of the option settings after cmake has run.
166    4.  A user submitted a patch to Makefile that makes it easy to create
167        "pcre.dll" under mingw when using Configure/Make. I added stuff to
168        Makefile.am that cause it to include this special target, without
169        affecting anything else. Note that the same mingw target plus all
170        the other distribution libraries and programs are now supported
171        when configuring with CMake (see 6 below) instead of with
172        Configure/Make.
174    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
175        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
176        exported in the Windows port". It has not yet been confirmed that the patch
177        solves the problem, but it does no harm.
179    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
180        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
181        with CMake, and also correct the comment about stack recursion.
183    7.  Remove the automatic building of pcredemo from the ./configure system and
184        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
185        of a program that users should build themselves after PCRE is installed, so
186        building it automatically is not really right. What is more, it gave
187        trouble in some build environments.
189    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
192    Version 7.5 10-Jan-08
193    ---------------------
195    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
196        values in parens when parsing an RE using the C++ wrapper."
198    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
199        Characters greater than 255 were excluded from the class instead of being
200        included.
202    3.  The same bug as (2) above applied to negated POSIX classes such as
203        [:^space:].
205    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
206        defined or documented. It seems to have been a typo for PCRE_STATIC, so
207        I have changed it.
209    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
210        first named subpattern) and a construct such as (?&a) would reference the
211        first named subpattern whose name started with "a" (in other words, the
212        length check was missing). Both these problems are fixed. "Subpattern name
213        expected" is now given for (?&) (a zero-length name), and this patch also
214        makes it give the same error for \k'' (previously it complained that that
215        was a reference to a non-existent subpattern).
217    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
218        this is right because (?- can be followed by option settings as well as by
219        digits. I have, however, made the messages clearer.
221    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
222        than the number used in the conditional) now cause a compile-time error.
223        This is actually not compatible with Perl, which accepts such patterns, but
224        treats the conditional as always being FALSE (as PCRE used to), but it
225        seems to me that giving a diagnostic is better.
227    8.  Change "alphameric" to the more common word "alphanumeric" in comments
228        and messages.
230    9.  Fix two occurrences of "backslash" in comments that should have been
231        "backspace".
233    10. Remove two redundant lines of code that can never be obeyed (their function
234        was moved elsewhere).
236    11. The program that makes PCRE's Unicode character property table had a bug
237        which caused it to generate incorrect table entries for sequences of
238        characters that have the same character type, but are in different scripts.
239        It amalgamated them into a single range, with the script of the first of
240        them. In other words, some characters were in the wrong script. There were
241        thirteen such cases, affecting characters in the following ranges:
243          U+002b0 - U+002c1
244          U+0060c - U+0060d
245          U+0061e - U+00612
246          U+0064b - U+0065e
247          U+0074d - U+0076d
248          U+01800 - U+01805
249          U+01d00 - U+01d77
250          U+01d9b - U+01dbf
251          U+0200b - U+0200f
252          U+030fc - U+030fe
253          U+03260 - U+0327f
254          U+0fb46 - U+0fbb1
255          U+10450 - U+1049d
257    12. The -o option (show only the matching part of a line) for pcregrep was not
258        compatible with GNU grep in that, if there was more than one match in a
259        line, it showed only the first of them. It now behaves in the same way as
260        GNU grep.
262    13. If the -o and -v options were combined for pcregrep, it printed a blank
263        line for every non-matching line. GNU grep prints nothing, and pcregrep now
264        does the same. The return code can be used to tell if there were any
265        non-matching lines.
267    14. Added --file-offsets and --line-offsets to pcregrep.
269    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
270        infinitely looping recursion. The bug was that positive lookaheads were not
271        being skipped when checking for a possible empty match (negative lookaheads
272        and both kinds of lookbehind were skipped).
274    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
275        inclusion of <windows.h> to before rather than after the definition of
276        INVALID_FILE_ATTRIBUTES (patch from David Byron).
278    17. Specifying a possessive quantifier with a specific limit for a Unicode
279        character property caused pcre_compile() to compile bad code, which led at
280        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
281        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
282        caused the error; without that there was no problem.
284    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
286    19. Added --enable-pcretest-libreadline.
288    20. In pcrecpp.cc, the variable 'count' was incremented twice in
289        RE::GlobalReplace(). As a result, the number of replacements returned was
290        double what it should be. I removed one of the increments, but Craig sent a
291        later patch that removed the other one (the right fix) and added unit tests
292        that check the return values (which was not done before).
294    21. Several CMake things:
296        (1) Arranged that, when cmake is used on Unix, the libraries end up with
297            the names libpcre and libpcreposix, not just pcre and pcreposix.
299        (2) The above change means that pcretest and pcregrep are now correctly
300            linked with the newly-built libraries, not previously installed ones.
304    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
305        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
306        UTF-8 newline character). The key issue is that the pattern starts .*;
307        this means that the match must be either at the beginning, or after a
308        newline. The bug was in the code for advancing after a failed match and
309        checking that the new position followed a newline. It was not taking
310        account of UTF-8 characters correctly.
312    23. PCRE was behaving differently from Perl in the way it recognized POSIX
313        character classes. PCRE was not treating the sequence [:...:] as a
314        character class unless the ... were all letters. Perl, however, seems to
315        allow any characters between [: and :], though of course it rejects as
316        unknown any "names" that contain non-letters, because all the known class
317        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
318        for example, whereas PCRE did not - it did not recognize a POSIX character
319        class. This seemed a bit dangerous, so the code has been changed to be
320        closer to Perl. The behaviour is not identical to Perl, because PCRE will
321        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
322        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
323        Perl does, and where it didn't before.
325    24. Rewrite so as to remove the single use of %n from pcregrep because in some
326        Windows environments %n is disabled by default.
329    Version 7.4 21-Sep-07
330    ---------------------
332    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
333        means that a class such as [\s] counted as "explicit reference to CR or
334        LF". That isn't really right - the whole point of the change was to try to
335        help when there was an actual mention of one of the two characters. So now
336        the change happens only if \r or \n (or a literal CR or LF) character is
337        encountered.
339    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
340        of both had grown to the point where there were only 3 bits left.
341        Fortunately, there was spare space in the data structure, and so I have
342        moved the internal flags into a new 16-bit field to free up more option
343        bits.
345    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
346        but did not set the internal JCHANGED flag - either of these is enough to
347        control the way the "get" function works - but the PCRE_INFO_JCHANGED
348        facility is supposed to tell if (?J) was ever used, so now (?J) at the
349        start sets both bits.
351    4.  Added options (at build time, compile time, exec time) to change \R from
352        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
354    5.  doc/pcresyntax.html was missing from the distribution.
356    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
357        compatibility, even though it is no longer used.
359    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
360        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
361        windows.h file is present (where different names are used). [This was
362        reversed later after testing - see 16 below.]
364    8.  Changed all #include <config.h> to #include "config.h". There were also
365        some further <pcre.h> cases that I changed to "pcre.h".
367    9.  When pcregrep was used with the --colour option, it missed the line ending
368        sequence off the lines that it output.
370    10. It was pointed out to me that arrays of string pointers cause lots of
371        relocations when a shared library is dynamically loaded. A technique of
372        using a single long string with a table of offsets can drastically reduce
373        these. I have refactored PCRE in four places to do this. The result is
374        dramatic:
376          Originally:                          290
377          After changing UCP table:            187
378          After changing error message table:   43
379          After changing table of "verbs"       36
380          After changing table of Posix names   22
382        Thanks to the folks working on Gregex for glib for this insight.
384    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
385        unicode-properties was also set.
387    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
389    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
390        checked only for CRLF.
392    14. Added casts to pcretest.c to avoid compiler warnings.
394    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
396    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
397        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
398        entirely. This removes changes made in 7 above.
400    17. The CMake files have been updated, and there is now more information about
401        building with CMake in the NON-UNIX-USE document.
404    Version 7.3 28-Aug-07
405    ---------------------
407     1. In the rejigging of the build system that eventually resulted in 7.1, the
408        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
409        brackets there is not right, since it causes compilers to look for an
410        installed pcre.h, not the version that is in the source that is being
411        compiled (which of course may be different). I have changed it back to:
413          #include "pcre.h"
415        I have a vague recollection that the change was concerned with compiling in
416        different directories, but in the new build system, that is taken care of
417        by the VPATH setting the Makefile.
419     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
420        when the subject happened to end in the byte 0x85 (e.g. if the last
421        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
422        characters but of course it shouldn't be taken as a newline when it is part
423        of another character. The bug was that, for an unlimited repeat of . in
424        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
425        characters when looking for a newline.
427     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
429     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
430        in debug output.
432     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
433        long printing in the pcrecpp unittest when running under MinGW.
435     6. ESC_K was left out of the EBCDIC table.
437     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
438        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
439        limit also applies to "virtual nesting" when a pattern is recursive, and in
440        this case 1000 isn't so big. I have been able to remove this limit at the
441        expense of backing off one optimization in certain circumstances. Normally,
442        when pcre_exec() would call its internal match() function recursively and
443        immediately return the result unconditionally, it uses a "tail recursion"
444        feature to save stack. However, when a subpattern that can match an empty
445        string has an unlimited repetition quantifier, it no longer makes this
446        optimization. That gives it a stack frame in which to save the data for
447        checking that an empty string has been matched. Previously this was taken
448        from the 1000-entry workspace that had been reserved. So now there is no
449        explicit limit, but more stack is used.
451     8. Applied Daniel's patches to solve problems with the import/export magic
452        syntax that is required for Windows, and which was going wrong for the
453        pcreposix and pcrecpp parts of the library. These were overlooked when this
454        problem was solved for the main library.
456     9. There were some crude static tests to avoid integer overflow when computing
457        the size of patterns that contain repeated groups with explicit upper
458        limits. As the maximum quantifier is 65535, the maximum group length was
459        set at 30,000 so that the product of these two numbers did not overflow a
460        32-bit integer. However, it turns out that people want to use groups that
461        are longer than 30,000 bytes (though not repeat them that many times).
462        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
463        made it possible to implement the integer overflow checks in a much more
464        dynamic way, which I have now done. The artificial limitation on group
465        length has been removed - we now have only the limit on the total length of
466        the compiled pattern, which depends on the LINK_SIZE setting.
468    10. Fixed a bug in the documentation for get/copy named substring when
469        duplicate names are permitted. If none of the named substrings are set, the
470        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
471        empty string.
473    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
474        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
475        because the ] is interpreted as the first data character and the
476        terminating ] is not found. PCRE has been made compatible with Perl in this
477        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
478        cause memory overwriting.
480    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
481        string has been matched (to stop an infinite loop). It was not recognizing
482        a conditional subpattern that could match an empty string if that
483        subpattern was within another subpattern. For example, it looped when
484        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
485        condition was not nested. This bug has been fixed.
487    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
488        past the start of the subject in the presence of bytes with the top bit
489        set, for example "\x8aBCD".
491    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
492        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
494    14. Optimized (?!) to (*FAIL).
496    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
497        This restricts code points to be within the range 0 to 0x10FFFF, excluding
498        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
499        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
500        does: it's just the validity check that is more restrictive.
502    16. Inserted checks for integer overflows during escape sequence (backslash)
503        processing, and also fixed erroneous offset values for syntax errors during
504        backslash processing.
506    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
507        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
509    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
510        caused an overrun.
512    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
513        something other than just ASCII characters) inside a group that had an
514        unlimited repeat caused a loop at compile time (while checking to see
515        whether the group could match an empty string).
517    20. Debugging a pattern containing \p or \P could cause a crash. For example,
518        [\P{Any}] did so. (Error in the code for printing property names.)
520    21. An orphan \E inside a character class could cause a crash.
522    22. A repeated capturing bracket such as (A)? could cause a wild memory
523        reference during compilation.
525    23. There are several functions in pcre_compile() that scan along a compiled
526        expression for various reasons (e.g. to see if it's fixed length for look
527        behind). There were bugs in these functions when a repeated \p or \P was
528        present in the pattern. These operators have additional parameters compared
529        with \d, etc, and these were not being taken into account when moving along
530        the compiled data. Specifically:
532        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
533            length.
535        (b) An item such as \pL+ within a repeated group could cause crashes or
536            loops.
538        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
539            "reference to non-existent subpattern" error.
541        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
543    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
544        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
546    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
548    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
549        character were causing crashes (broken optimization).
551    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
552        \p or \P) caused a compile-time loop.
554    28. More problems have arisen in unanchored patterns when CRLF is a valid line
555        break. For example, the unstudied pattern [\r\n]A does not match the string
556        "\r\nA" because change 7.0/46 below moves the current point on by two
557        characters after failing to match at the start. However, the pattern \nA
558        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
559        the same is true. There doesn't seem any very clean way out of this, but
560        what I have chosen to do makes the common cases work: PCRE now takes note
561        of whether there can be an explicit match for \r or \n anywhere in the
562        pattern, and if so, 7.0/46 no longer applies. As part of this change,
563        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
564        pattern has explicit CR or LF references.
566    29. Added (*CR) etc for changing newline setting at start of pattern.
569    Version 7.2 19-Jun-07
570    ---------------------
572     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
573        which is apparently normally available under Windows.
575     2. Re-jig the pcregrep tests with different newline settings in an attempt
576        to make them independent of the local environment's newline setting.
578     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
580     4. Some of the "internals" tests were previously cut out when the link size
581        was not 2, because the output contained actual offsets. The recent new
582        "Z" feature of pcretest means that these can be cut out, making the tests
583        usable with all link sizes.
585     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
586        stack recursion. This gives a massive performance boost under BSD, but just
587        a small improvement under Linux. However, it saves one field in the frame
588        in all cases.
590     6. Added more features from the forthcoming Perl 5.10:
592        (a) (?-n) (where n is a string of digits) is a relative subroutine or
593            recursion call. It refers to the nth most recently opened parentheses.
595        (b) (?+n) is also a relative subroutine call; it refers to the nth next
596            to be opened parentheses.
598        (c) Conditions that refer to capturing parentheses can be specified
599            relatively, for example, (?(-2)... or (?(+3)...
601        (d) \K resets the start of the current match so that everything before
602            is not part of it.
604        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
606        (f) \g{name} is another synonym - part of Perl 5.10's unification of
607            reference syntax.
609        (g) (?| introduces a group in which the numbering of parentheses in each
610            alternative starts with the same number.
612        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
614     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
617     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
618        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
619        for detecting groups that can match an empty string.
621     9. A pattern with a very large number of alternatives (more than several
622        hundred) was running out of internal workspace during the pre-compile
623        phase, where pcre_compile() figures out how much memory will be needed. A
624        bit of new cunning has reduced the workspace needed for groups with
625        alternatives. The 1000-alternative test pattern now uses 12 bytes of
626        workspace instead of running out of the 4096 that are available.
628    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
630    11. Applied patch from Google to remove an optimization that didn't quite work.
631        The report of the bug said:
633          pcrecpp::RE("a*").FullMatch("aaa") matches, while
634          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
635          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
637    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
638        it matched the wrong number of bytes.
641    Version 7.1 24-Apr-07
642    ---------------------
644     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
645        that is more "standard", making use of automake and other Autotools. There
646        is some re-arrangement of the files and adjustment of comments consequent
647        on this.
649     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
650        for recursive directory scanning broke on some systems because the files
651        are not scanned in any specific order and on different systems the order
652        was different. A call to "sort" has been inserted into RunGrepTest for the
653        approprate test as a short-term fix. In the longer term there may be an
654        alternative.
656     3. I had an email from Eric Raymond about problems translating some of PCRE's
657        man pages to HTML (despite the fact that I distribute HTML pages, some
658        people do their own conversions for various reasons). The problems
659        concerned the use of low-level troff macros .br and .in. I have therefore
660        removed all such uses from the man pages (some were redundant, some could
661        be replaced by .nf/.fi pairs). The 132html script that I use to generate
662        HTML has been updated to handle .nf/.fi and to complain if it encounters
663        .br or .in.
665     4. Updated comments in configure.ac that get placed in config.h.in and also
666        arranged for config.h to be included in the distribution, with the name
667        config.h.generic, for the benefit of those who have to compile without
668        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
670     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
671        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
672        makevp.bat for the current PCRE, using the additional files
673        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
675     6. A Windows user reported a minor discrepancy with test 2, which turned out
676        to be caused by a trailing space on an input line that had got lost in his
677        copy. The trailing space was an accident, so I've just removed it.
679     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
680        that is needed.
682     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
683        as "const" (a) because they are and (b) because it helps the PHP
684        maintainers who have recently made a script to detect big data structures
685        in the php code that should be moved to the .rodata section. I remembered
686        to update Builducptable as well, so it won't revert if ucptable.h is ever
687        re-created.
689     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
690        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
691        order to be able to cut out the UTF-8 tables in the latter when UTF-8
692        support is not required. This saves 1.5-2K of code, which is important in
693        some applications.
695        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
696        so as not to refer to the tables, even though these functions will never be
697        called when UTF-8 support is disabled. Otherwise there are problems with a
698        shared library.
700    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
702        (a) It was defining its arguments as char * instead of void *.
704        (b) It was assuming that all moves were upwards in memory; this was true
705            a long time ago when I wrote it, but is no longer the case.
707        The emulated memove() is provided for those environments that have neither
708        memmove() nor bcopy(). I didn't think anyone used it these days, but that
709        is clearly not the case, as these two bugs were recently reported.
711    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
712        and Detrail to create the HTML documentation, the .txt form of the man
713        pages, and it removes trailing spaces from listed files. It also creates
714        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
715        case, it wraps all the #defines with #ifndefs. This script should be run
716        before "make dist".
718    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
719        with Unicode property support.
721        (a) For a maximizing quantifier, if the two different cases of the
722            character were of different lengths in their UTF-8 codings (there are
723            some cases like this - I found 11), and the matching function had to
724            back up over a mixture of the two cases, it incorrectly assumed they
725            were both the same length.
727        (b) When PCRE was configured to use the heap rather than the stack for
728            recursion during matching, it was not correctly preserving the data for
729            the other case of a UTF-8 character when checking ahead for a match
730            while processing a minimizing repeat. If the check also involved
731            matching a wide character, but failed, corruption could cause an
732            erroneous result when trying to check for a repeat of the original
733            character.
735    13. Some tidying changes to the testing mechanism:
737        (a) The RunTest script now detects the internal link size and whether there
738            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
739            values substituted by "configure". (The RunGrepTest script already did
740            this for UTF-8.) The configure.ac script no longer substitutes the
741            relevant variables.
743        (b) The debugging options /B and /D in pcretest show the compiled bytecode
744            with length and offset values. This means that the output is different
745            for different internal link sizes. Test 2 is skipped for link sizes
746            other than 2 because of this, bypassing the problem. Unfortunately,
747            there was also a test in test 3 (the locale tests) that used /B and
748            failed for link sizes other than 2. Rather than cut the whole test out,
749            I have added a new /Z option to pcretest that replaces the length and
750            offset values with spaces. This is now used to make test 3 independent
751            of link size. (Test 2 will be tidied up later.)
753    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
754        segmentation fault instead of returning the appropriate error message.
756    15. In multiline mode when the newline sequence was set to "any", the pattern
757        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
758        This doesn't seem right; it now treats the CRLF combination as the line
759        ending, and so does not match in that case. It's only a pattern such as ^$
760        that would hit this one: something like ^ABC$ would have failed after \r
761        and then tried again after \r\n.
763    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
764        in an attempt to make files that differ only in their line terminators
765        compare equal. This works on Linux.
767    17. Under certain error circumstances pcregrep might try to free random memory
768        as it exited. This is now fixed, thanks to valgrind.
770    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
771        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
772        was because its rules for how to advance for /g after matching an empty
773        string at the end of a line did not allow for this case. They now check for
774        it specially.
776    20. pcretest is supposed to handle patterns and data of any length, by
777        extending its buffers when necessary. It was getting this wrong when the
778        buffer for a data line had to be extended.
780    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
781        CRLF as a newline sequence.
783    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
784        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
785        I have nevertheless tidied it up.
787    23. Added some casts to kill warnings from HP-UX ia64 compiler.
789    24. Added a man page for pcre-config.
792    Version 7.0 19-Dec-06
793    ---------------------
795     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
796        moving to gcc 4.1.1.
798     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
799        sys/time.h, which is documented as needed for this function. It doesn't
800        seem to matter on Linux, but it showed up on some releases of OS X.
802     3. It seems that there are systems where bytes whose values are greater than
803        127 match isprint() in the "C" locale. The "C" locale should be the
804        default when a C program starts up. In most systems, only ASCII printing
805        characters match isprint(). This difference caused the output from pcretest
806        to vary, making some of the tests fail. I have changed pcretest so that:
808        (a) When it is outputting text in the compiled version of a pattern, bytes
809            other than 32-126 are always shown as hex escapes.
811        (b) When it is outputting text that is a matched part of a subject string,
812            it does the same, unless a different locale has been set for the match
813            (using the /L modifier). In this case, it uses isprint() to decide.
815     4. Fixed a major bug that caused incorrect computation of the amount of memory
816        required for a compiled pattern when options that changed within the
817        pattern affected the logic of the preliminary scan that determines the
818        length. The relevant options are -x, and -i in UTF-8 mode. The result was
819        that the computed length was too small. The symptoms of this bug were
820        either the PCRE error "internal error: code overflow" from pcre_compile(),
821        or a glibc crash with a message such as "pcretest: free(): invalid next
822        size (fast)". Examples of patterns that provoked this bug (shown in
823        pcretest format) are:
825          /(?-x: )/x
826          /(?x)(?-x: \s*#\s*)/
827          /((?i)[\x{c0}])/8
828          /(?i:[\x{c0}])/8
830        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
831        is now done differently.
833     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
834        wrapper classes; (b) implement a new function in the C++ scanner that is
835        more efficient than the old way of doing things because it avoids levels of
836        recursion in the regex matching; (c) add a paragraph to the documentation
837        for the FullMatch() function.
839     6. The escape sequence \n was being treated as whatever was defined as
840        "newline". Not only was this contrary to the documentation, which states
841        that \n is character 10 (hex 0A), but it also went horribly wrong when
842        "newline" was defined as CRLF. This has been fixed.
844     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
845        was being set to -1 for the "end of line" case (supposedly a value that no
846        character can have). Though this value is never used (the check for end of
847        line is "zero bytes in current character"), it caused compiler complaints.
848        I've changed it to 0xffffffff.
850     8. In pcre_version.c, the version string was being built by a sequence of
851        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
852        string (as it is for production releases) called a macro with an empty
853        argument. The C standard says the result of this is undefined. The gcc
854        compiler treats it as an empty string (which was what was wanted) but it is
855        reported that Visual C gives an error. The source has been hacked around to
856        avoid this problem.
858     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
859        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
860        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
861        of them did).
863    10. Originally, pcretest opened its input and output without "b"; then I was
864        told that "b" was needed in some environments, so it was added for release
865        5.0 to both the input and output. (It makes no difference on Unix-like
866        systems.) Later I was told that it is wrong for the input on Windows. I've
867        now abstracted the modes into two macros, to make it easier to fiddle with
868        them, and removed "b" from the input mode under Windows.
870    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
872    12. Added -help and --help to pcretest as an official way of being reminded
873        of the options.
875    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
876        and pcrecpp.cc because they annoy compilers at high warning levels.
878    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
880    15. Fixed an occurrence of == in configure.ac that should have been = (shell
881        scripts are not C programs :-) and which was not noticed because it works
882        on Linux.
884    16. pcretest is supposed to handle any length of pattern and data line (as one
885        line or as a continued sequence of lines) by extending its input buffer if
886        necessary. This feature was broken for very long pattern lines, leading to
887        a string of junk being passed to pcre_compile() if the pattern was longer
888        than about 50K.
890    17. I have done a major re-factoring of the way pcre_compile() computes the
891        amount of memory needed for a compiled pattern. Previously, there was code
892        that made a preliminary scan of the pattern in order to do this. That was
893        OK when PCRE was new, but as the facilities have expanded, it has become
894        harder and harder to keep it in step with the real compile phase, and there
895        have been a number of bugs (see for example, 4 above). I have now found a
896        cunning way of running the real compile function in a "fake" mode that
897        enables it to compute how much memory it would need, while actually only
898        ever using a few hundred bytes of working memory and without too many
899        tests of the mode. This should make future maintenance and development
900        easier. A side effect of this work is that the limit of 200 on the nesting
901        depth of parentheses has been removed (though this was never a serious
902        limitation, I suspect). However, there is a downside: pcre_compile() now
903        runs more slowly than before (30% or more, depending on the pattern). I
904        hope this isn't a big issue. There is no effect on runtime performance.
906    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
907        newline (only possible for the last line of a file) and it was a
908        pattern that set a locale (followed by /Lsomething), pcretest crashed.
910    19. Added additional timing features to pcretest. (1) The -tm option now times
911        matching only, not compiling. (2) Both -t and -tm can be followed, as a
912        separate command line item, by a number that specifies the number of
913        repeats to use when timing. The default is 50000; this gives better
914        precision, but takes uncomfortably long for very large patterns.
916    20. Extended pcre_study() to be more clever in cases where a branch of a
917        subpattern has no definite first character. For example, (a*|b*)[cd] would
918        previously give no result from pcre_study(). Now it recognizes that the
919        first character must be a, b, c, or d.
921    21. There was an incorrect error "recursive call could loop indefinitely" if
922        a subpattern (or the entire pattern) that was being tested for matching an
923        empty string contained only one non-empty item after a nested subpattern.
924        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
925        incorrectly, because the \d was being skipped in the check.
927    22. The pcretest program now has a new pattern option /B and a command line
928        option -b, which is equivalent to adding /B to every pattern. This causes
929        it to show the compiled bytecode, without the additional information that
930        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
931        is the same as /B/I).
933    23. A new optimization is now able automatically to treat some sequences such
934        as a*b as a*+b. More specifically, if something simple (such as a character
935        or a simple class like \d) has an unlimited quantifier, and is followed by
936        something that cannot possibly match the quantified thing, the quantifier
937        is automatically "possessified".
939    24. A recursive reference to a subpattern whose number was greater than 39
940        went wrong under certain circumstances in UTF-8 mode. This bug could also
941        have affected the operation of pcre_study().
943    25. Realized that a little bit of performance could be had by replacing
944        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
946    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
948    27. Possessive quantifiers such as a++ were previously implemented by turning
949        them into atomic groups such as ($>a+). Now they have their own opcodes,
950        which improves performance. This includes the automatically created ones
951        from 23 above.
953    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
954        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
955        the first matched character to be a colon. This applied both to named and
956        numbered groups.
958    29. The ucpinternal.h header file was missing its idempotency #ifdef.
960    30. I was sent a "project" file called libpcre.a.dev which I understand makes
961        building PCRE on Windows easier, so I have included it in the distribution.
963    31. There is now a check in pcretest against a ridiculously large number being
964        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
965        loop, the loop is abandoned.
967    32. Forward references to subpatterns in conditions such as (?(2)...) where
968        subpattern 2 is defined later cause pcre_compile() to search forwards in
969        the pattern for the relevant set of parentheses. This search went wrong
970        when there were unescaped parentheses in a character class, parentheses
971        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
973    33. "Subroutine" calls and backreferences were previously restricted to
974        referencing subpatterns earlier in the regex. This restriction has now
975        been removed.
977    34. Added a number of extra features that are going to be in Perl 5.10. On the
978        whole, these are just syntactic alternatives for features that PCRE had
979        previously implemented using the Python syntax or my own invention. The
980        other formats are all retained for compatibility.
982        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
983            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
984            also .NET compatible.
986        (b) A recursion or subroutine call to a named group can now be defined as
987            (?&name) as well as (?P>name).
989        (c) A backreference to a named group can now be defined as \k<name> or
990            \k'name' as well as (?P=name). The new forms, as well as being in Perl
991            5.10, are also .NET compatible.
993        (d) A conditional reference to a named group can now use the syntax
994            (?(<name>) or (?('name') as well as (?(name).
996        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
997            groups (named and numbered) that are never evaluated inline, but can be
998            called as "subroutines" from elsewhere. In effect, the DEFINE condition
999            is always false. There may be only one alternative in such a group.
1001        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1002            as the simple (?(R). The condition is true only if the most recent
1003            recursion is that of the given number or name. It does not search out
1004            through the entire recursion stack.
1006        (g) The escape \gN or \g{N} has been added, where N is a positive or
1007            negative number, specifying an absolute or relative reference.
1009    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1010        some "unreachable code" warnings.
1012    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1013        things, this adds five new scripts.
1015    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1016        There were also incompatibilities regarding the handling of \Q..\E inside
1017        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1018        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1020    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1021        matches an empty string, and forcibly breaks the loop. There were bugs in
1022        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1023        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1024        separate and independent bugs (that affected different cases) have been
1025        fixed.
1027    39. Refactored the code to abolish the use of different opcodes for small
1028        capturing bracket numbers. This is a tidy that I avoided doing when I
1029        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1030        The new approach is not only tidier, it makes it possible to reduce the
1031        memory needed to fix the previous bug (38).
1033    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1034        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1035        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1036        mode.
1038    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1039        report.
1041    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1042        copy construction and assignment in the C++ wrapper.
1044    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1045        couple of bugs that could have given wrong results in the "--newline=crlf"
1046        case.
1048    44. Added a number of casts and did some reorganization of signed/unsigned int
1049        variables following suggestions from Dair Grant. Also renamed the variable
1050        "this" as "item" because it is a C++ keyword.
1052    45. Arranged for dftables to add
1054          #include "pcre_internal.h"
1056        to pcre_chartables.c because without it, gcc 4.x may remove the array
1057        definition from the final binary if PCRE is built into a static library and
1058        dead code stripping is activated.
1060    46. For an unanchored pattern, if a match attempt fails at the start of a
1061        newline sequence, and the newline setting is CRLF or ANY, and the next two
1062        characters are CRLF, advance by two characters instead of one.
1065    Version 6.7 04-Jul-06
1066    ---------------------
1068     1. In order to handle tests when input lines are enormously long, pcretest has
1069        been re-factored so that it automatically extends its buffers when
1070        necessary. The code is crude, but this _is_ just a test program. The
1071        default size has been increased from 32K to 50K.
1073     2. The code in pcre_study() was using the value of the re argument before
1074        testing it for NULL. (Of course, in any sensible call of the function, it
1075        won't be NULL.)
1077     3. The memmove() emulation function in pcre_internal.h, which is used on
1078        systems that lack both memmove() and bcopy() - that is, hardly ever -
1079        was missing a "static" storage class specifier.
1081     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1082        containing an extended class (one that cannot be represented by a bitmap
1083        because it contains high-valued characters or Unicode property items, e.g.
1084        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1085        pattern, but PCRE should not loop if you do not (it no longer does).
1086        [Detail: two cases were found: (a) a repeated subpattern containing an
1087        extended class; (b) a recursive reference to a subpattern that followed a
1088        previous extended class. It wasn't skipping over the extended class
1089        correctly when UTF-8 mode was not set.]
1091     5. A negated single-character class was not being recognized as fixed-length
1092        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1093        compile error "lookbehind assertion is not fixed length".
1095     6. The RunPerlTest auxiliary script was showing an unexpected difference
1096        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1097        write a Perl script that can interpret lines of an input file either as
1098        byte characters or as UTF-8, which is what "perltest" was being required to
1099        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1100        can't do is switch easily at run time between having the "use utf8;" pragma
1101        or not. In the end, I fudged it by using the RunPerlTest script to insert
1102        "use utf8;" explicitly for the UTF-8 tests.
1104     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1105        the end of the subject string, contrary to the documentation and to what
1106        Perl does. This was true of both matching functions. Now it matches only at
1107        the start of the subject and immediately after *internal* newlines.
1109     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1110        a pointer to an int instead of a pointer to an unsigned long int. This
1111        caused problems on 64-bit systems.
1113     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1114        instance of the 'standard' template library not being so standard".
1116    10. There was no check on the number of named subpatterns nor the maximum
1117        length of a subpattern name. The product of these values is used to compute
1118        the size of the memory block for a compiled pattern. By supplying a very
1119        long subpattern name and a large number of named subpatterns, the size
1120        computation could be caused to overflow. This is now prevented by limiting
1121        the length of names to 32 characters, and the number of named subpatterns
1122        to 10,000.
1124    11. Subpatterns that are repeated with specific counts have to be replicated in
1125        the compiled pattern. The size of memory for this was computed from the
1126        length of the subpattern and the repeat count. The latter is limited to
1127        65535, but there was no limit on the former, meaning that integer overflow
1128        could in principle occur. The compiled length of a repeated subpattern is
1129        now limited to 30,000 bytes in order to prevent this.
1131    12. Added the optional facility to have named substrings with the same name.
1133    13. Added the ability to use a named substring as a condition, using the
1134        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1135        are numbers (not recommended). Forward references are permitted.
1137    14. Added forward references in named backreferences (if you see what I mean).
1139    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1140        pattern could run off the end of the subject. For example, the pattern
1141        "(?s)(.{1,5})"8 did this with the subject "ab".
1143    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1144        PCRE_CASELESS was set when matching characters that were quantified with ?
1145        or *.
1147    17. A character class other than a single negated character that had a minimum
1148        but no maximum quantifier - for example [ab]{6,} - was not handled
1149        correctly by pce_dfa_exec(). It would match only one character.
1151    18. A valid (though odd) pattern that looked like a POSIX character
1152        class but used an invalid character after [ (for example [[,abc,]]) caused
1153        pcre_compile() to give the error "Failed: internal error: code overflow" or
1154        in some cases to crash with a glibc free() error. This could even happen if
1155        the pattern terminated after [[ but there just happened to be a sequence of
1156        letters, a binary zero, and a closing ] in the memory that followed.
1158    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1159        over the years. Originally (before any Unicode support), just the bottom 8
1160        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1161        output from "man perlunicode" includes this:
1163          The regular expression compiler produces polymorphic opcodes.  That
1164          is, the pattern adapts to the data and automatically switches to
1165          the Unicode character scheme when presented with Unicode data--or
1166          instead uses a traditional byte scheme when presented with byte
1167          data.
1169        Sadly, a wide octal escape does not cause a switch, and in a string with
1170        no other multibyte characters, these octal escapes are treated as before.
1171        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1172        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1173        Unicode string.
1175        I have not perpetrated such confusion in PCRE. Up till now, it took just
1176        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1177        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1178        translate to the appropriate multibyte character.
1180    29. Applied some refactoring to reduce the number of warnings from Microsoft
1181        and Borland compilers. This has included removing the fudge introduced
1182        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1183        a warning about an unused variable.
1185    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1186        characters since release 4.0, because Perl (from release 5.004) does not.
1187        [Or at least, is documented not to: some releases seem to be in conflict
1188        with the documentation.] However, when a pattern was studied with
1189        pcre_study() and all its branches started with \s, PCRE still included VT
1190        as a possible starting character. Of course, this did no harm; it just
1191        caused an unnecessary match attempt.
1193    22. Removed a now-redundant internal flag bit that recorded the fact that case
1194        dependency changed within the pattern. This was once needed for "required
1195        byte" processing, but is no longer used. This recovers a now-scarce options
1196        bit. Also moved the least significant internal flag bit to the most-
1197        significant bit of the word, which was not previously used (hangover from
1198        the days when it was an int rather than a uint) to free up another bit for
1199        the future.
1201    23. Added support for CRLF line endings as well as CR and LF. As well as the
1202        default being selectable at build time, it can now be changed at runtime
1203        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1204        specify that it is scanning data with non-default line endings.
1206    24. Changed the definition of CXXLINK to make it agree with the definition of
1207        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1209    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1210        recursions. This makes a big different to stack usage for some patterns.
1212    26. If a subpattern containing a named recursion or subroutine reference such
1213        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1214        the space required for the compiled pattern went wrong and gave too small a
1215        value. Depending on the environment, this could lead to "Failed: internal
1216        error: code overflow at offset 49" or "glibc detected double free or
1217        corruption" errors.
1219    27. Applied patches from Google (a) to support the new newline modes and (b) to
1220        advance over multibyte UTF-8 characters in GlobalReplace.
1222    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1223        difference for some implementation of PCRE in some Windows version.
1225    29. Added some extra testing facilities to pcretest:
1227        \q<number>   in a data line sets the "match limit" value
1228        \Q<number>   in a data line sets the "match recursion limt" value
1229        -S <number>  sets the stack size, where <number> is in megabytes
1231        The -S option isn't available for Windows.
1234    Version 6.6 06-Feb-06
1235    ---------------------
1237     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1238        in pcreposix.h. I have copied the definition from pcre.h.
1240     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1241        because pcre.h is no longer a built file.
1243     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1244        not normally included in the compiled code.
1247    Version 6.5 01-Feb-06
1248    ---------------------
1250     1. When using the partial match feature with pcre_dfa_exec(), it was not
1251        anchoring the second and subsequent partial matches at the new starting
1252        point. This could lead to incorrect results. For example, with the pattern
1253        /1234/, partially matching against "123" and then "a4" gave a match.
1255     2. Changes to pcregrep:
1257        (a) All non-match returns from pcre_exec() were being treated as failures
1258            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1259            error message is output. Some extra information is given for the
1260            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1261            probably the only errors that are likely to be caused by users (by
1262            specifying a regex that has nested indefinite repeats, for instance).
1263            If there are more than 20 of these errors, pcregrep is abandoned.
1265        (b) A binary zero was treated as data while matching, but terminated the
1266            output line if it was written out. This has been fixed: binary zeroes
1267            are now no different to any other data bytes.
1269        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1270            used to set a locale for matching. The --locale=xxxx long option has
1271            been added (no short equivalent) to specify a locale explicitly on the
1272            pcregrep command, overriding the environment variables.
1274        (d) When -B was used with -n, some line numbers in the output were one less
1275            than they should have been.
1277        (e) Added the -o (--only-matching) option.
1279        (f) If -A or -C was used with -c (count only), some lines of context were
1280            accidentally printed for the final match.
1282        (g) Added the -H (--with-filename) option.
1284        (h) The combination of options -rh failed to suppress file names for files
1285            that were found from directory arguments.
1287        (i) Added the -D (--devices) and -d (--directories) options.
1289        (j) Added the -F (--fixed-strings) option.
1291        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1293        (l) Added the --colo(u)r option.
1295        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1296            is not present by default.
1298     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1299        items such as (?R) or (?1), when the recursion could match a number of
1300        alternatives. If it matched one of the alternatives, but subsequently,
1301        outside the recursion, there was a failure, the code tried to back up into
1302        the recursion. However, because of the way PCRE is implemented, this is not
1303        possible, and the result was an incorrect result from the match.
1305        In order to prevent this happening, the specification of recursion has
1306        been changed so that all such subpatterns are automatically treated as
1307        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1309     4. I had overlooked the fact that, in some locales, there are characters for
1310        which isalpha() is true but neither isupper() nor islower() are true. In
1311        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1312        and ordfeminine) are like this. This affected the treatment of \w and \W
1313        when they appeared in character classes, but not when they appeared outside
1314        a character class. The bit map for "word" characters is now created
1315        separately from the results of isalnum() instead of just taking it from the
1316        upper, lower, and digit maps. (Plus the underscore character, of course.)
1318     5. The above bug also affected the handling of POSIX character classes such as
1319        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1320        permanent tables. Instead, the bit maps for such a class were previously
1321        created as the appropriate unions of the upper, lower, and digit bitmaps.
1322        Now they are created by subtraction from the [[:word:]] class, which has
1323        its own bitmap.
1325     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1326        It is created by subtracting the vertical space characters (\x09, \x0a,
1327        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1328        subtraction was done in the overall bitmap for a character class, meaning
1329        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1330        be recognized. This bug has been fixed.
1332     7. Patches from the folks at Google:
1334          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1335          real life, but is still worth protecting against".
1337          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1338          regular expressions".
1340          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1341          have it.
1343          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1344          "configure" and the latter not, in order to fix a problem somebody had
1345          with compiling the Arg class on HP-UX.
1347          (e) Improve the error-handling of the C++ wrapper a little bit.
1349          (f) New tests for checking recursion limiting.
1351     8. The pcre_memmove() function, which is used only if the environment does not
1352        have a standard memmove() function (and is therefore rarely compiled),
1353        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1354        returning a result (though PCRE never actually uses the result).
1356     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1357        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1358        returned instead of calling malloc() with an overflowing number that would
1359        most likely cause subsequent chaos.
1361    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1363    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1364        with this option is matched, the nmatch and pmatch options of regexec() are
1365        ignored.
1367    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1368        provided in case anyone wants to the the POSIX interface with UTF-8
1369        strings.
1371    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1372        C++ linking (needed for some HP-UX environments).
1374    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1375        (unused parameter) and in the pcre_printint() function (omitted "default"
1376        switch label when the default is to do nothing).
1378    15. Added some code to make it possible, when PCRE is compiled as a C++
1379        library, to replace subject pointers for pcre_exec() with a smart pointer
1380        class, thus making it possible to process discontinuous strings.
1382    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1383        much the same function. They were added by different people who were trying
1384        to make PCRE easy to compile on non-Unix systems. It has been suggested
1385        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1386        for compiling on Windows systems. I have therefore replaced it with
1387        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1388        defaults to "extern" for C or "extern C" for C++, which works fine on
1389        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1390        SCOPE with something explicit in config.h. In addition:
1392        (a) pcreposix.h still had just "extern" instead of either of these macros;
1393            I have replaced it with PCRE_DATA_SCOPE.
1395        (b) Functions such as _pcre_xclass(), which are internal to the library,
1396            but external in the C sense, all had PCRE_EXPORT in their definitions.
1397            This is apparently wrong for the Windows case, so I have removed it.
1398            (It makes no difference on Unix-like systems.)
1400    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1401        of recursive calls to match(). This is different to MATCH_LIMIT because
1402        that limits the total number of calls to match(), not all of which increase
1403        the depth of recursion. Limiting the recursion depth limits the amount of
1404        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1405        when PCRE is compiled, and changed at run time. A patch from Google adds
1406        this functionality to the C++ interface.
1408    18. Changes to the handling of Unicode character properties:
1410        (a) Updated the table to Unicode 4.1.0.
1412        (b) Recognize characters that are not in the table as "Cn" (undefined).
1414        (c) I revised the way the table is implemented to a much improved format
1415            which includes recognition of ranges. It now supports the ranges that
1416            are defined in UnicodeData.txt, and it also amalgamates other
1417            characters into ranges. This has reduced the number of entries in the
1418            table from around 16,000 to around 3,000, thus reducing its size
1419            considerably. I realized I did not need to use a tree structure after
1420            all - a binary chop search is just as efficient. Having reduced the
1421            number of entries, I extended their size from 6 bytes to 8 bytes to
1422            allow for more data.
1424        (d) Added support for Unicode script names via properties such as \p{Han}.
1426    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1427        matching that character.
1429    20. When matching a repeated Unicode property with a minimum greater than zero,
1430        (for example \pL{2,}), PCRE could look past the end of the subject if it
1431        reached it while seeking the minimum number of characters. This could
1432        happen only if some of the characters were more than one byte long, because
1433        there is a check for at least the minimum number of bytes.
1435    21. Refactored the implementation of \p and \P so as to be more general, to
1436        allow for more different types of property in future. This has changed the
1437        compiled form incompatibly. Anybody with saved compiled patterns that use
1438        \p or \P will have to recompile them.
1440    22. Added "Any" and "L&" to the supported property types.
1442    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1443        but give a compile time error if the value is greater than 0xff.
1445    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1446        accidentally not being installed or uninstalled.
1448    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1449        made were to insert the current release number. This seemed silly, because
1450        it made things harder for people building PCRE on systems that don't run
1451        "configure". I have turned pcre.h into a distributed file, no longer built
1452        by "configure", with the version identification directly included. There is
1453        no longer a pcre.h.in file.
1455        However, this change necessitated a change to the pcre-config script as
1456        well. It is built from pcre-config.in, and one of the substitutions was the
1457        release number. I have updated configure.ac so that ./configure now finds
1458        the release number by grepping pcre.h.
1460    26. Added the ability to run the tests under valgrind.
1463    Version 6.4 05-Sep-05
1464    ---------------------
1466     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1467        "--" to be printed when multiple files were scanned, even when none of the
1468        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1469        consider it to be a bug, and have restored the previous behaviour.
1471     2. A couple of code tidies to get rid of compiler warnings.
1473     3. The pcretest program used to cheat by referring to symbols in the library
1474        whose names begin with _pcre_. These are internal symbols that are not
1475        really supposed to be visible externally, and in some environments it is
1476        possible to suppress them. The cheating is now confined to including
1477        certain files from the library's source, which is a bit cleaner.
1479     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1480        file's purpose clearer.
1482     5. Reorganized pcre_ucp_findchar().
1485    Version 6.3 15-Aug-05
1486    ---------------------
1488     1. The file libpcre.pc.in did not have general read permission in the tarball.
1490     2. There were some problems when building without C++ support:
1492        (a) If C++ support was not built, "make install" and "make test" still
1493            tried to test it.
1495        (b) There were problems when the value of CXX was explicitly set. Some
1496            changes have been made to try to fix these, and ...
1498        (c) --disable-cpp can now be used to explicitly disable C++ support.
1500        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1501            backslash in a target when C++ was disabled. This confuses some
1502            versions of "make", apparently. Using an intermediate variable solves
1503            this. (Same for CPP_LOBJ.)
1505     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1506        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1507        necessary on certain architectures.
1509     4. Added a setting of -export-symbols-regex to the link command to remove
1510        those symbols that are exported in the C sense, but actually are local
1511        within the library, and not documented. Their names all begin with
1512        "_pcre_". This is not a perfect job, because (a) we have to except some
1513        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1514        available (and never for static libraries). I have made a note to try to
1515        find a way round (a) in the future.
1518    Version 6.2 01-Aug-05
1519    ---------------------
1521     1. There was no test for integer overflow of quantifier values. A construction
1522        such as {1111111111111111} would give undefined results. What is worse, if
1523        a minimum quantifier for a parenthesized subpattern overflowed and became
1524        negative, the calculation of the memory size went wrong. This could have
1525        led to memory overwriting.
1527     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1529     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1530        operating environments where this matters.
1532     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1533        PCRE options from within the C++ wrapper.
1535     5. Named capturing subpatterns were not being correctly counted when a pattern
1536        was compiled. This caused two problems: (a) If there were more than 100
1537        such subpatterns, the calculation of the memory needed for the whole
1538        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1539        back references of the form \12, where the number was greater than 9, were
1540        not recognized as back references, even though there were sufficient
1541        previous subpatterns.
1543     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1544        versions of gcc, e.g. 2.95.4.
1547    Version 6.1 21-Jun-05
1548    ---------------------
1550     1. There was one reference to the variable "posix" in pcretest.c that was not
1551        surrounded by "#if !defined NOPOSIX".
1553     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1554        the cross-check on the old pcre_info() function, for the benefit of the
1555        cut-down version of PCRE that is currently imported into Exim.
1557     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1558        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1559        patterns that start (?i) but I don't think that matters. The use of (?i) is
1560        just an example; this all applies to the other options as well.
1562     4. Since libtool seems to echo the compile commands it is issuing, the output
1563        from "make" can be reduced a bit by putting "@" in front of each libtool
1564        compile command.
1566     5. Patch from the folks at Google for configure.in to be a bit more thorough
1567        in checking for a suitable C++ installation before trying to compile the
1568        C++ stuff. This should fix a reported problem when a compiler was present,
1569        but no suitable headers.
1571     6. The man pages all had just "PCRE" as their title. I have changed them to
1572        be the relevant file name. I have also arranged that these names are
1573        retained in the file doc/pcre.txt, which is a concatenation in text format
1574        of all the man pages except the little individual ones for each function.
1576     7. The NON-UNIX-USE file had not been updated for the different set of source
1577        files that come with release 6. I also added a few comments about the C++
1578        wrapper.
1581    Version 6.0 07-Jun-05
1582    ---------------------
1584     1. Some minor internal re-organization to help with my DFA experiments.
1586     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1587        didn't matter for the library itself when fully configured, but did matter
1588        when compiling without UCP support, or within Exim, where the ucp files are
1589        not imported.
1591     3. Refactoring of the library code to split up the various functions into
1592        different source modules. The addition of the new DFA matching code (see
1593        below) to a single monolithic source would have made it really too
1594        unwieldy, quite apart from causing all the code to be include in a
1595        statically linked application, when only some functions are used. This is
1596        relevant even without the DFA addition now that patterns can be compiled in
1597        one application and matched in another.
1599        The downside of splitting up is that there have to be some external
1600        functions and data tables that are used internally in different modules of
1601        the library but which are not part of the API. These have all had their
1602        names changed to start with "_pcre_" so that they are unlikely to clash
1603        with other external names.
1605     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1606        a different (DFA) algorithm. Although it is slower than the original
1607        function, it does have some advantages for certain types of matching
1608        problem.
1610     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1611        including restarting after a partial match.
1613     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1614        defined when compiling for Windows was sent to me. I have put it into the
1615        code, though I have no means of testing or verifying it.
1617     7. Added the pcre_refcount() auxiliary function.
1619     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1620        match before or at the first newline in the subject string. In pcretest,
1621        the /f option on a pattern can be used to set this.
1623     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1624        would behave wrongly. This has been present in PCRE since release 4.0.
1626    10. A number of changes to the pcregrep command:
1628        (a) Refactored how -x works; insert ^(...)$ instead of setting
1629            PCRE_ANCHORED and checking the length, in preparation for adding
1630            something similar for -w.
1632        (b) Added the -w (match as a word) option.
1634        (c) Refactored the way lines are read and buffered so as to have more
1635            than one at a time available.
1637        (d) Implemented a pcregrep test script.
1639        (e) Added the -M (multiline match) option. This allows patterns to match
1640            over several lines of the subject. The buffering ensures that at least
1641            8K, or the rest of the document (whichever is the shorter) is available
1642            for matching (and similarly the previous 8K for lookbehind assertions).
1644        (f) Changed the --help output so that it now says
1646              -w, --word-regex(p)
1648            instead of two lines, one with "regex" and the other with "regexp"
1649            because that confused at least one person since the short forms are the
1650            same. (This required a bit of code, as the output is generated
1651            automatically from a table. It wasn't just a text change.)
1653        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1654            option but starts with a hyphen. Could be a pattern or a path name
1655            starting with a hyphen, for instance.
1657        (h) "-" can be given as a file name to represent stdin.
1659        (i) When file names are being printed, "(standard input)" is used for
1660            the standard input, for compatibility with GNU grep. Previously
1661            "<stdin>" was used.
1663        (j) The option --label=xxx can be used to supply a name to be used for
1664            stdin when file names are being printed. There is no short form.
1666        (k) Re-factored the options decoding logic because we are going to add
1667            two more options that take data. Such options can now be given in four
1668            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1670        (l) Added the -A, -B, and -C options for requesting that lines of context
1671            around matches be printed.
1673        (m) Added the -L option to print the names of files that do not contain
1674            any matching lines, that is, the complement of -l.
1676        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1677            continue to scan other files.
1679        (o) The -s option was incorrectly implemented. For compatibility with other
1680            greps, it now suppresses the error message for a non-existent or non-
1681            accessible file (but not the return code). There is a new option called
1682            -q that suppresses the output of matching lines, which was what -s was
1683            previously doing.
1685        (p) Added --include and --exclude options to specify files for inclusion
1686            and exclusion when recursing.
1688    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1689        Hopefully, it now does.
1691    12. Missing cast in pcre_study().
1693    13. Added an "uninstall" target to the makefile.
1695    14. Replaced "extern" in the function prototypes in Makefile.in with
1696        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1697        world, but is set differently for Windows.
1699    15. Added a second compiling function called pcre_compile2(). The only
1700        difference is that it has an extra argument, which is a pointer to an
1701        integer error code. When there is a compile-time failure, this is set
1702        non-zero, in addition to the error test pointer being set to point to an
1703        error message. The new argument may be NULL if no error number is required
1704        (but then you may as well call pcre_compile(), which is now just a
1705        wrapper). This facility is provided because some applications need a
1706        numeric error indication, but it has also enabled me to tidy up the way
1707        compile-time errors are handled in the POSIX wrapper.
1709    16. Added VPATH=.libs to the makefile; this should help when building with one
1710        prefix path and installing with another. (Or so I'm told by someone who
1711        knows more about this stuff than I do.)
1713    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1714        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1715        match everything, including newlines. This is not POSIX-compatible, but
1716        somebody wanted the feature. From pcretest it can be activated by using
1717        both the P and the s flags.
1719    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1721    19. libpcre.pc was being incorrectly installed as executable.
1723    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1724        it now also looks for '\r' so that it will work unmodified on Windows.
1726    21. Added Google's contributed C++ wrapper to the distribution.
1728    22. Added some untidy missing memory free() calls in pcretest, to keep
1729        Electric Fence happy when testing.
1733    Version 5.0 13-Sep-04
1734    ---------------------
1736     1. Internal change: literal characters are no longer packed up into items
1737        containing multiple characters in a single byte-string. Each character
1738        is now matched using a separate opcode. However, there may be more than one
1739        byte in the character in UTF-8 mode.
1741     2. The pcre_callout_block structure has two new fields: pattern_position and
1742        next_item_length. These contain the offset in the pattern to the next match
1743        item, and its length, respectively.
1745     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1746        insertion of callouts before each pattern item. Added the /C option to
1747        pcretest to make use of this.
1749     4. On the advice of a Windows user, the lines
1751          #if defined(_WIN32) || defined(WIN32)
1752          _setmode( _fileno( stdout ), 0x8000 );
1753          #endif  /* defined(_WIN32) || defined(WIN32) */
1755        have been added to the source of pcretest. This apparently does useful
1756        magic in relation to line terminators.
1758     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1759        for the benefit of those environments where the "b" makes a difference.
1761     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1762        to know about it. I have put a hack into configure.in that adds in code
1763        to set GCC=yes if CC=icc. This seems to end up at a point in the
1764        generated configure script that is early enough to affect the setting of
1765        compiler options, which is what is needed, but I have no means of testing
1766        whether it really works. (The user who reported this had patched the
1767        generated configure script, which of course I cannot do.)
1769        LATER: After change 22 below (new libtool files), the configure script
1770        seems to know about icc (and also ecc). Therefore, I have commented out
1771        this hack in configure.in.
1773     7. Added support for pkg-config (2 patches were sent in).
1775     8. Negated POSIX character classes that used a combination of internal tables
1776        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1777        [[:^ascii]]. Typically, they would match almost any characters. The other
1778        POSIX classes were not broken in this way.
1780     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1781        to find the match, as PCRE was deluded into thinking that the match had to
1782        start at the start point or following a newline. The same bug applied to
1783        patterns with negative forward assertions or any backward assertions
1784        preceding ".*" at the start, unless the pattern required a fixed first
1785        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1787    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1788        starting at the last subject character, bytes beyond the end of the subject
1789        string were read.
1791    11. Renamed the variable "class" as "classbits" to make life easier for C++
1792        users. (Previously there was a macro definition, but it apparently wasn't
1793        enough.)
1795    12. Added the new field "tables" to the extra data so that tables can be passed
1796        in at exec time, or the internal tables can be re-selected. This allows
1797        a compiled regex to be saved and re-used at a later time by a different
1798        program that might have everything at different addresses.
1800    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1801        -R library as well as a -L library.
1803    14. The debugging options of pcretest (-d on the command line or D on a
1804        pattern) showed incorrect output for anything following an extended class
1805        that contained multibyte characters and which was followed by a quantifier.
1807    15. Added optional support for general category Unicode character properties
1808        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1809        support. It adds about 90K to the size of the library. The meanings of the
1810        inbuilt class escapes such as \d and \s have NOT been changed.
1812    16. Updated pcredemo.c to include calls to free() to release the memory for the
1813        compiled pattern.
1815    17. The generated file chartables.c was being created in the source directory
1816        instead of in the building directory. This caused the build to fail if the
1817        source directory was different from the building directory, and was
1818        read-only.
1820    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1821        file. No doubt somebody will tell me if they don't make sense... Also added
1822        Dan Mooney's comments about building on OpenVMS.
1824    19. Added support for partial matching via the PCRE_PARTIAL option for
1825        pcre_exec() and the \P data escape in pcretest.
1827    20. Extended pcretest with 3 new pattern features:
1829        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1830              write the compiled pattern to the file whose name is "rest-of-line".
1831              This is a straight binary dump of the data, with the saved pointer to
1832              the character tables forced to be NULL. The study data, if any, is
1833              written too. After writing, pcretest reads a new pattern.
1835        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1836              compiled pattern from the given file. There must not be any
1837              occurrences of "<" in the file name (pretty unlikely); if there are,
1838              pcretest will instead treat the initial "<" as a pattern delimiter.
1839              After reading in the pattern, pcretest goes on to read data lines as
1840              usual.
1842        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1843              and 16-bit fields in a compiled pattern, to simulate a pattern that
1844              was compiled on a host of opposite endianness.
1846    21. The pcre-exec() function can now cope with patterns that were compiled on
1847        hosts of opposite endianness, with this restriction:
1849          As for any compiled expression that is saved and used later, the tables
1850          pointer field cannot be preserved; the extra_data field in the arguments
1851          to pcre_exec() should be used to pass in a tables address if a value
1852          other than the default internal tables were used at compile time.
1854    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1855        now diagnosed as an error. Previously, most of the time, a negative number
1856        would have been treated as zero, but if in addition "ovector" was passed as
1857        NULL, a crash could occur.
1859    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1860        new versions from the libtool 1.5 distribution (the last one is a copy of
1861        a file called libtool.m4). This seems to have fixed the need to patch
1862        "configure" to support Darwin 1.3 (which I used to do). However, I still
1863        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1864        workstation).
1866    24. Changed the PCRE licence to be the more standard "BSD" licence.
1869    Version 4.5 01-Dec-03
1870    ---------------------
1872     1. There has been some re-arrangement of the code for the match() function so
1873        that it can be compiled in a version that does not call itself recursively.
1874        Instead, it keeps those local variables that need separate instances for
1875        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1876        needs to "recurse". Keeping track of where control must go is done by means
1877        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1878        hide most of the details from the main code, and operates only if
1879        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1880        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1881        operating.
1883        To make it easier for callers to provide specially tailored get/free
1884        functions for this usage, two new functions, pcre_stack_malloc, and
1885        pcre_stack_free, are used. They are always called in strict stacking order,
1886        and the size of block requested is always the same.
1888        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1889        PCRE has been compiled to use the stack or the heap for recursion. The
1890        -C option of pcretest uses this to show which version is compiled.
1892        A new data escape \S, is added to pcretest; it causes the amounts of store
1893        obtained and freed by both kinds of malloc/free at match time to be added
1894        to the output.
1896     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1897        what's available on my current Linux desktop machine.
1899     3. When matching a UTF-8 string, the test for a valid string at the start has
1900        been extended. If start_offset is not zero, PCRE now checks that it points
1901        to a byte that is the start of a UTF-8 character. If not, it returns
1902        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1903        this is necessary because there may be backward assertions in the pattern.
1904        When matching the same subject several times, it may save resources to use
1905        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1907     4. The code for checking the validity of UTF-8 strings has been tightened so
1908        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1909        containing "overlong sequences".
1911     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1912        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1913        should have been "&", but it just so happened that all the cases this let
1914        through by mistake were picked up later in the function.
1916     6. I had used a variable called "isblank" - this is a C99 function, causing
1917        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1919     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1920        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1921        so the version is shown; (c) stop "make test" echoing "./RunTest".
1923     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1925     9. The prototype for memmove() for systems that don't have it was using
1926        size_t, but the inclusion of the header that defines size_t was later. I've
1927        moved the #includes for the C headers earlier to avoid this.
1929    10. Added some adjustments to the code to make it easier to compiler on certain
1930        special systems:
1932          (a) Some "const" qualifiers were missing.
1933          (b) Added the macro EXPORT before all exported functions; by default this
1934              is defined to be empty.
1935          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1936              that it reads its output file name as an argument instead of writing
1937              to the standard output and assuming this can be redirected.
1939    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1940        class containing characters with values greater than 255, PCRE compilation
1941        went into a loop.
1943    12. A recursive reference to a subpattern that was within another subpattern
1944        that had a minimum quantifier of zero caused PCRE to crash. For example,
1945        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1946        recursion. If the recursively-called subpattern itself had a zero repeat,
1947        that was OK.
1949    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1950        buffer into which it was copied (for escape processing) was still set at
1951        1024, so long lines caused crashes.
1953    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1954        "internal error: code overflow...". This applied to any character class
1955        that was followed by a possessive quantifier.
1957    15. Modified the Makefile to add libpcre.la as a prerequisite for
1958        libpcreposix.la because I was told this is needed for a parallel build to
1959        work.
1961    16. If a pattern that contained .* following optional items at the start was
1962        studied, the wrong optimizing data was generated, leading to matching
1963        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1964        matching string must start with a or b or c. The correct conclusion for
1965        this pattern is that a match can start with any character.
1968    Version 4.4 13-Aug-03
1969    ---------------------
1971     1. In UTF-8 mode, a character class containing characters with values between
1972        127 and 255 was not handled correctly if the compiled pattern was studied.
1973        In fixing this, I have also improved the studying algorithm for such
1974        classes (slightly).
1976     2. Three internal functions had redundant arguments passed to them. Removal
1977        might give a very teeny performance improvement.
1979     3. Documentation bug: the value of the capture_top field in a callout is *one
1980        more than* the number of the hightest numbered captured substring.
1982     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1983        in incorrectly linking with a previously installed version. They now link
1984        explicitly with libpcre.la.
1986     5. configure.in no longer needs to recognize Cygwin specially.
1988     6. A problem in pcre.in for Windows platforms is fixed.
1990     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1991        pcretest, it used to include the size of the study block as part of its
1992        output. Unfortunately, the structure contains a field that has a different
1993        size on different hardware architectures. This meant that the tests that
1994        showed this size failed. As the block is currently always of a fixed size,
1995        this information isn't actually particularly useful in pcretest output, so
1996        I have just removed it.
1998     8. Three pre-processor statements accidentally did not start in column 1.
1999        Sadly, there are *still* compilers around that complain, even though
2000        standard C has not required this for well over a decade. Sigh.
2002     9. In pcretest, the code for checking callouts passed small integers in the
2003        callout_data field, which is a void * field. However, some picky compilers
2004        complained about the casts involved for this on 64-bit systems. Now
2005        pcretest passes the address of the small integer instead, which should get
2006        rid of the warnings.
2008    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2009        both compile and run time, and gives an error if an invalid UTF-8 sequence
2010        is found. There is a option for disabling this check in cases where the
2011        string is known to be correct and/or the maximum performance is wanted.
2013    11. In response to a bug report, I changed one line in Makefile.in from
2015            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2016        to
2017            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2019        to look similar to other lines, but I have no way of telling whether this
2020        is the right thing to do, as I do not use Windows. No doubt I'll get told
2021        if it's wrong...
2024    Version 4.3 21-May-03
2025    ---------------------
2027    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2028       Makefile.
2030    2. Some refactoring to improve the quality of the code:
2032       (i)   The utf8_table... variables are now declared "const".
2034       (ii)  The code for \cx, which used the "case flipping" table to upper case
2035             lower case letters, now just substracts 32. This is ASCII-specific,
2036             but the whole concept of \cx is ASCII-specific, so it seems
2037             reasonable.
2039       (iii) PCRE was using its character types table to recognize decimal and
2040             hexadecimal digits in the pattern. This is silly, because it handles
2041             only 0-9, a-f, and A-F, but the character types table is locale-
2042             specific, which means strange things might happen. A private
2043             table is now used for this - though it costs 256 bytes, a table is
2044             much faster than multiple explicit tests. Of course, the standard
2045             character types table is still used for matching digits in subject
2046             strings against \d.
2048       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2049             ending in _t are). So I've renamed it as ESC_tee.
2051    3. The first argument for regexec() in the POSIX wrapper should have been
2052       defined as "const".
2054    4. Changed pcretest to use malloc() for its buffers so that they can be
2055       Electric Fenced for debugging.
2057    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2058       to read one or more bytes before the start of the subject string. Often this
2059       had no effect on PCRE's behaviour, but in some circumstances it could
2060       provoke a segmentation fault.
2062    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2063       to try to read one or more bytes before the start of the subject string.
2065    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2066       UTF-8 support could misbehave in various ways if the subject string
2067       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2068       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2069       back over UTF-8 characters.)
2072    Version 4.2 14-Apr-03
2073    ---------------------
2075    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2077    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2078         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2079         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2080         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2081         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2082           and BUILD_EXEEXT
2083         Note: automatic setting of the BUILD variables is not yet working
2084         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2085           compile-time but not at link-time
2086         [LINK]: use for linking executables only
2087         make different versions for Windows and non-Windows
2088         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2089           libraries
2090         [LINK_FOR_BUILD]: new variable
2091         [OBJEXT]: use throughout
2092         [EXEEXT]: use throughout
2093         <winshared>: new target
2094         <wininstall>: new target
2095         <dftables.o>: use native compiler
2096         <dftables>: use native linker
2097         <install>: handle Windows platform correctly
2098         <clean>: ditto
2099         <check>: ditto
2100         copy DLL to top builddir before testing
2102       As part of these changes, -no-undefined was removed again. This was reported
2103       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2104       in any case.
2106    3. Some tidies to get rid of compiler warnings:
2108       . In the match_data structure, match_limit was an unsigned long int, whereas
2109         match_call_count was an int. I've made them both unsigned long ints.
2111       . In pcretest the fact that a const uschar * doesn't automatically cast to
2112         a void * provoked a warning.
2114       . Turning on some more compiler warnings threw up some "shadow" variables
2115         and a few more missing casts.
2117    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2118       option, a class that contained a single character with a value between 128
2119       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2121    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2122       option, a class that contained several characters, but with at least one
2123       whose value was between 128 and 255 caused PCRE to crash.
2126    Version 4.1 12-Mar-03
2127    ---------------------
2129    1. Compiling with gcc -pedantic found a couple of places where casts were
2130    needed, and a string in dftables.c that was longer than standard compilers are
2131    required to support.
2133    2. Compiling with Sun's compiler found a few more places where the code could
2134    be tidied up in order to avoid warnings.
2136    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2137    first of these names is deprecated in the latest Autoconf in favour of the name
2138    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2139    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2140    analogy I have changed it to CFLAGS_FOR_BUILD.
2142    4. Added -no-undefined to the linking command in the Makefile, because this is
2143    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2144    linking step for the pcreposix library.
2146    5. PCRE was failing to diagnose the case of two named groups with the same
2147    name.
2149    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2150    literal character that is needed in the subject for a match, and scans along to
2151    ensure that it is present before embarking on the full matching process. This
2152    saves time in cases of nested unlimited repeats that are never going to match.
2153    Problem: the scan can take a lot of time if the subject is very long (e.g.
2154    megabytes), thus penalizing straightforward matches. It is now done only if the
2155    amount of subject to be scanned is less than 1000 bytes.
2157    7. A lesser problem with the same optimization is that it was recording the
2158    first character of an anchored pattern as "needed", thus provoking a search
2159    right along the subject, even when the first match of the pattern was going to
2160    fail. The "needed" character is now not set for anchored patterns, unless it
2161    follows something in the pattern that is of non-fixed length. Thus, it still
2162    fulfils its original purpose of finding quick non-matches in cases of nested
2163    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2166    Version 4.0 17-Feb-03
2167    ---------------------
2169    1. If a comment in an extended regex that started immediately after a meta-item
2170    extended to the end of string, PCRE compiled incorrect data. This could lead to
2171    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2173    2. Moved to autoconf 2.53 and libtool 1.4.2.
2175    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2176    the special perltest8 script is no longer needed - all the tests can be run
2177    from a single perltest script.
2179    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2180    by \s. It has now been removed in PCRE. This means it isn't recognized as
2181    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2182    class [:space:] *does* include VT, thereby creating a mess.
2184    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2185    space and tab.
2187    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2188    its new features into the main test script, reducing the number of scripts.
2190    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2191    were backward compatible, and made the (?i) apply to the whole pattern, as if
2192    /i were given. Now it behaves more logically, and applies the option setting
2193    only to what follows. PCRE has been changed to follow suit. However, if it
2194    finds options settings right at the start of the pattern, it extracts them into
2195    the global options, as before. Thus, they show up in the info data.
2197    8. Added support for the \Q...\E escape sequence. Characters in between are
2198    treated as literals. This is slightly different from Perl in that $ and @ are
2199    also handled as literals inside the quotes. In Perl, they will cause variable
2200    interpolation. Note the following examples:
2202        Pattern            PCRE matches      Perl matches
2204        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2205        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2206        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2208    For compatibility with Perl, \Q...\E sequences are recognized inside character
2209    classes as well as outside them.
2211    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2212    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2213    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2214    signed/unsigned warnings.
2216    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2217    option for pcretest, so I've replaced it by a simple function that does just
2218    that job.
2220    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2221    "pcregrep -".
2223    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2224    Java package. This provides some syntactic sugar for simple cases of what my
2225    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2226    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2227    item, you can use this simplified notation. Note that only makes sense with
2228    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2229    greediness, whatever the setting of the PCRE_UNGREEDY option.
2231    13. A change of greediness default within a pattern was not taking effect at
2232    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2233    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2234    was abstracted outside.
2236    14. PCRE now supports the \G assertion. It is true when the current matching
2237    position is at the start point of the match. This differs from \A when the
2238    starting offset is non-zero. Used with the /g option of pcretest (or similar
2239    code), it works in the same way as it does for Perl's /g option. If all
2240    alternatives of a regex begin with \G, the expression is anchored to the start
2241    match position, and the "anchored" flag is set in the compiled expression.
2243    15. Some bugs concerning the handling of certain option changes within patterns
2244    have been fixed. These applied to options other than (?ims). For example,
2245    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2246    been the other way round. Some of this was related to change 7 above.
2248    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2249    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2250    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2251    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2253    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2254    mode. Unlike ".", it always matches newline, whatever the setting of
2255    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2256    assertions. Perl allows it, but it doesn't (in general) work because it can't
2257    calculate the length of the lookbehind. At least, that's the case for Perl
2258    5.8.0 - I've been told they are going to document that it doesn't work in
2259    future.
2261    18. Added an error diagnosis for escapes that PCRE does not support: these are
2262    \L, \l, \N, \P, \p, \U, \u, and \X.
2264    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2265    reading past the end of the pattern in cases such as /[abcd/.
2267    20. PCRE was getting more memory than necessary for patterns with classes that
2268    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2270    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2271    compiling PCRE for use with Virtual Pascal.
2273    22. Small fix to the Makefile to make it work properly if the build is done
2274    outside the source tree.
2276    23. Added a new extension: a condition to go with recursion. If a conditional
2277    subpattern starts with (?(R) the "true" branch is used if recursion has
2278    happened, whereas the "false" branch is used only at the top level.
2280    24. When there was a very long string of literal characters (over 255 bytes
2281    without UTF support, over 250 bytes with UTF support), the computation of how
2282    much memory was required could be incorrect, leading to segfaults or other
2283    strange effects.
2285    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2286    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2287    there was a subsequent back reference to those brackets. This meant that, for
2288    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2289    possible to check for precisely this case. All we can do is abandon the
2290    optimization if .* occurs inside capturing brackets when there are any back
2291    references whatsoever. (See below for a better fix that came later.)
2293    26. The handling of the optimization for finding the first character of a
2294    non-anchored pattern, and for finding a character that is required later in the
2295    match were failing in some cases. This didn't break the matching; it just
2296    failed to optimize when it could. The way this is done has been re-implemented.
2298    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2300    28. Added a new feature that provides some of the functionality that Perl
2301    provides with (?{...}). The facility is termed a "callout". The way it is done
2302    in PCRE is for the caller to provide an optional function, by setting
2303    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2304    global variable. By default it is unset, which disables all calling out. To get
2305    the function called, the regex must include (?C) at appropriate points. This
2306    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2307    This provides a means of identifying different callout points. When PCRE
2308    reaches such a point in the regex, if pcre_callout has been set, the external
2309    function is called. It is provided with data in a structure called
2310    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2311    matching continues; if it returns a non-zero value, the match at the current
2312    point fails. However, backtracking will occur if possible. [This was changed
2313    later and other features added - see item 49 below.]
2315    29. pcretest is upgraded to test the callout functionality. It provides a
2316    callout function that displays information. By default, it shows the start of
2317    the match and the current position in the text. There are some new data escapes
2318    to vary what happens:
2320        \C+         in addition, show current contents of captured substrings
2321        \C-         do not supply a callout function
2322        \C!n        return 1 when callout number n is reached
2323        \C!n!m      return 1 when callout number n is reached for the mth time
2325    30. If pcregrep was called with the -l option and just a single file name, it
2326    output "<stdin>" if a match was found, instead of the file name.
2328    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2329    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2330    pcre_exec(). This saves a malloc/free per call. The default value of
2331    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2332    when configuring.
2334    32. The default maximum size of a compiled pattern is 64K. There have been a
2335    few cases of people hitting this limit. The code now uses macros to handle the
2336    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2337    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2338    configuring. Tests 2 and 5 work only with 2-byte links because they output
2339    debugging information about compiled patterns.
2341    33. Internal code re-arrangements:
2343    (a) Moved the debugging function for printing out a compiled regex into
2344        its own source file (printint.c) and used #include to pull it into
2345        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2346        separate copies.
2348    (b) Defined the list of op-code names for debugging as a macro in
2349        internal.h so that it is next to the definition of the opcodes.
2351    (c) Defined a table of op-code lengths for simpler skipping along compiled
2352        code. This is again a macro in internal.h so that it is next to the
2353        definition of the opcodes.
2355    34. Added support for recursive calls to individual subpatterns, along the
2356    lines of Robin Houston's patch (but implemented somewhat differently).
2358    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2359    allow it to read and process whole directories in Win32. This code was
2360    contributed by Lionel Fourquaux; it has not been tested by me.
2362    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2363    used to name a group. Names consist of alphanumerics and underscores, and must
2364    be unique. Back references use the syntax (?P=name) and recursive calls use
2365    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2366    numbers. The function pcre_fullinfo() can be used after compilation to extract
2367    a name/number map. There are three relevant calls:
2369      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2370      PCRE_INFO_NAMECOUNT            yields the number of entries
2371      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2373    The map is a vector of fixed-size entries. The size of each entry depends on
2374    the length of the longest name used. The first two bytes of each entry are the
2375    group number, most significant byte first. There follows the corresponding
2376    name, zero terminated. The names are in alphabetical order.
2378    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2379    case instead of 255. Making it the same both with and without UTF-8 support
2380    means that the same test output works with both.
2382    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2383    calling malloc() with a zero argument.
2385    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2386    optimization. I've improved things by keeping a bitmap of backreferences with
2387    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2388    fact referenced, the optimization can be applied. It is unlikely that a
2389    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2390    the match to follow \n) will appear inside brackets with a number greater than
2391    31, but if it does, any back reference > 31 suppresses the optimization.
2393    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2394    of disabling numbered capturing parentheses. Any opening parenthesis that is
2395    not followed by ? behaves as if it were followed by ?: but named parentheses
2396    can still be used for capturing (and they will acquire numbers in the usual
2397    way).
2399    41. Redesigned the return codes from the match() function into yes/no/error so
2400    that errors can be passed back from deep inside the nested calls. A malloc
2401    failure while inside a recursive subpattern call now causes the
2402    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2404    42. It is now possible to set a limit on the number of times the match()
2405    function is called in a call to pcre_exec(). This facility makes it possible to
2406    limit the amount of recursion and backtracking, though not in a directly
2407    obvious way, because the match() function is used in a number of different
2408    circumstances. The count starts from zero for each position in the subject
2409    string (for non-anchored patterns). The default limit is, for compatibility, a
2410    large number, namely 10 000 000. You can change this in two ways:
2412    (a) When configuring PCRE before making, you can use --with-match-limit=n
2413        to set a default value for the compiled library.
2415    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2416        a different value is set. See 45 below.
2418    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2420    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2421    of things that can be changed at compile time. The first argument specifies
2422    what is wanted and the second points to where the information is to be placed.
2423    The current list of available information is:
2425      PCRE_CONFIG_UTF8
2427    The output is an integer that is set to one if UTF-8 support is available;
2428    otherwise it is set to zero.
2432    The output is an integer that it set to the value of the code that is used for
2433    newline. It is either LF (10) or CR (13).
2437    The output is an integer that contains the number of bytes used for internal
2438    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2442    The output is an integer that contains the threshold above which the POSIX
2443    interface uses malloc() for output vectors. See item 31 above.
2447    The output is an unsigned integer that contains the default limit of the number
2448    of match() calls in a pcre_exec() execution. See 42 above.
2450    44. pcretest has been upgraded by the addition of the -C option. This causes it
2451    to extract all the available output from the new pcre_config() function, and to
2452    output it. The program then exits immediately.
2454    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2455    order to support additional features. One way would have been to define
2456    pcre_exec2() (for example) with extra arguments, but this would not have been
2457    extensible, and would also have required all calls to the original function to
2458    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2459    is used for passing in "extra" data from pcre_study().
2461    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2462    contains the following fields:
2464      flags         a bitmap indicating which of the following fields are set
2465      study_data    opaque data from pcre_study()
2466      match_limit   a way of specifying a limit on match() calls for a specific
2467                      call to pcre_exec()
2468      callout_data  data for callouts (see 49 below)
2470    The flag bits are also defined in pcre.h, and are
2476    The pcre_study() function now returns one of these new pcre_extra blocks, with
2477    the actual study data pointed to by the study_data field, and the
2478    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2479    before. That is, this change is entirely upwards-compatible and requires no
2480    change to existing code.
2482    If you want to pass in additional data to pcre_exec(), you can either place it
2483    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2484    block.
2486    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2487    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2488    times with different match limits, until it finds the minimum value needed for
2489    pcre_exec() to complete. The value is then output. This can be instructive; for
2490    most simple matches the number is quite small, but for pathological cases it
2491    gets very large very quickly.
2493    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2494    returns the size of the data block pointed to by the study_data field in a
2495    pcre_extra block, that is, the value that was passed as the argument to
2496    pcre_malloc() when PCRE was getting memory in which to place the information
2497    created by pcre_study(). The fourth argument should point to a size_t variable.
2498    pcretest has been extended so that this information is shown after a successful
2499    pcre_study() call when information about the compiled regex is being displayed.
2501    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2502    because what follows is always an absolute path. (Later: it turns out that this
2503    is more than cosmetic for MinGW, because it doesn't like empty path
2504    components.)
2506    49. Some changes have been made to the callout feature (see 28 above):
2508    (i)  A callout function now has three choices for what it returns:
2510           0  =>  success, carry on matching
2511         > 0  =>  failure at this point, but backtrack if possible
2512         < 0  =>  serious error, return this value from pcre_exec()
2514         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2515         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2516         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2517         use by callout functions. It will never be used by PCRE itself.
2519    (ii) The pcre_extra structure (see 45 above) has a void * field called
2520         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2521         pcre_callout_block structure has a field of the same name. The contents of
2522         the field passed in the pcre_extra structure are passed to the callout
2523         function in the corresponding field in the callout block. This makes it
2524         easier to use the same callout-containing regex from multiple threads. For
2525         testing, the pcretest program has a new data escape
2527           \C*n        pass the number n (may be negative) as callout_data
2529         If the callout function in pcretest receives a non-zero value as
2530         callout_data, it returns that value.
2532    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2533    there were some redundant $(CFLAGS) in commands that are now specified as
2534    $(LINK), which already includes $(CFLAGS).
2536    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2537    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2538    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2539    one-byte characters throughout. Note that case-insensitive matching applies
2540    only to characters whose values are less than 256. PCRE doesn't support the
2541    notion of cases for higher-valued characters.
2543    (i)   A character class whose characters are all within 0-255 is handled as
2544          a bit map, and the map is inverted for negative classes. Previously, a
2545          character > 255 always failed to match such a class; however it should
2546          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2548    (ii)  A negated character class with a single character < 255 is coded as
2549          "not this character" (OP_NOT). This wasn't working properly when the test
2550          character was multibyte, either singly or repeated.
2552    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2553          mode, for example: \x{100}{2,3}.
2555    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2556          singly or repeated) now correctly test multibyte characters. However,
2557          PCRE doesn't recognize any characters with values greater than 255 as
2558          digits, spaces, or word characters. Such characters always match \D, \S,
2559          and \W, and never match \d, \s, or \w.
2561    (v)   Classes may now contain characters and character ranges with values
2562          greater than 255. For example: [ab\x{100}-\x{400}].
2564    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2565          PCRE in UTF-8 mode.
2567    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2568    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2569    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2570    value.)
2572    53. The single man page has become too large. I have therefore split it up into
2573    a number of separate man pages. These also give rise to individual HTML pages;
2574    these are now put in a separate directory, and there is an index.html page that
2575    lists them all. Some hyperlinking between the pages has been installed.
2577    54. Added convenience functions for handling named capturing parentheses.
2579    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2580    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2581    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2582    are faulted.
2584    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2585    calling configure. These values are used when compiling the dftables.c program
2586    which is run to generate the source of the default character tables. They
2587    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2588    you will need to set these values.
2590    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2593    Version 3.9 02-Jan-02
2594    ---------------------
2596    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2598    2. If --disable-static was given, the building process failed when trying to
2599    build pcretest and pcregrep. (For some reason it was using libtool to compile
2600    them, which is not right, as they aren't part of the library.)
2603    Version 3.8 18-Dec-01
2604    ---------------------
2606    1. The experimental UTF-8 code was completely screwed up. It was packing the
2607    bytes in the wrong order. How dumb can you get?
2610    Version 3.7 29-Oct-01
2611    ---------------------
2613    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2614    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2615    this didn't happen under Solaris 8, where I normally test things.
2617    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2618    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2619    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2620    this fix an hour or so after the initial 3.7 release.)
2623    Version 3.6 23-Oct-01
2624    ---------------------
2626    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2627    offsets passed as NULL with zero offset count.
2629    2. The config.guess and config.sub files had not been updated when I moved to
2630    the latest autoconf.
2633    Version 3.5 15-Aug-01
2634    ---------------------
2636    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2637    had been forgotten.
2639    2. By using declared but undefined structures, we can avoid using "void"
2640    definitions in pcre.h while keeping the internal definitions of the structures
2641    private.
2643    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2644    user point of view, this means that both static and shared libraries are built
2645    by default, but this can be individually controlled. More of the work of
2646    handling this static/shared cases is now inside libtool instead of PCRE's make
2647    file.
2649    4. The pcretest utility is now installed along with pcregrep because it is
2650    useful for users (to test regexs) and by doing this, it automatically gets
2651    relinked by libtool. The documentation has been turned into a man page, so
2652    there are now .1, .txt, and .html versions in /doc.
2654    5. Upgrades to pcregrep:
2655       (i)   Added long-form option names like gnu grep.
2656       (ii)  Added --help to list all options with an explanatory phrase.
2657       (iii) Added -r, --recursive to recurse into sub-directories.
2658       (iv)  Added -f, --file to read patterns from a file.
2660    6. pcre_exec() was referring to its "code" argument before testing that
2661    argument for NULL (and giving an error if it was NULL).
2663    7. Upgraded Makefile.in to allow for compiling in a different directory from
2664    the source directory.
2666    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2667    options bits, the pointer it was passed was to an int instead of to an unsigned
2668    long int. This mattered only on 64-bit systems.
2670    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2671    generated) instead of pcre.in, which it its source. Also made the same change
2672    in several of the .c files.
2674    10. A new release of gcc defines printf() as a macro, which broke pcretest
2675    because it had an ifdef in the middle of a string argument for printf(). Fixed
2676    by using separate calls to printf().
2678    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2679    script, to force use of CR or LF instead of \n in the source. On non-Unix
2680    systems, the value can be set in config.h.
2682    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2683    absolute limit. Changed the text of the error message to make this clear, and
2684    likewise updated the man page.
2686    13. The limit of 99 on the number of capturing subpatterns has been removed.
2687    The new limit is 65535, which I hope will not be a "real" limit.
2690    Version 3.4 22-Aug-00
2691    ---------------------
2693    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2695    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2698  Version 3.3 01-Aug-00  Version 3.3 01-Aug-00
2699  ---------------------  ---------------------

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