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ChangeLog for PCRE

Version 7.3 28-Aug-07

 1. In the rejigging of the build system that eventually resulted in 7.1, the
    line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
    brackets there is not right, since it causes compilers to look for an
    installed pcre.h, not the version that is in the source that is being
    compiled (which of course may be different). I have changed it back to:

      #include "pcre.h"

    I have a vague recollection that the change was concerned with compiling in
    different directories, but in the new build system, that is taken care of
    by the VPATH setting the Makefile.

 2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
    when the subject happened to end in the byte 0x85 (e.g. if the last
    character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
    characters but of course it shouldn't be taken as a newline when it is part
    of another character. The bug was that, for an unlimited repeat of . in
    not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
    characters when looking for a newline.

 3. A small performance improvement in the DOTALL UTF-8 mode .* case.

 4. Debugging: adjusted the names of opcodes for different kinds of parentheses
    in debug output.

 5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
    long printing in the pcrecpp unittest when running under MinGW.

 6. ESC_K was left out of the EBCDIC table.

 7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
    parentheses; I made it 1000, which seemed large enough. Unfortunately, the
    limit also applies to "virtual nesting" when a pattern is recursive, and in
    this case 1000 isn't so big. I have been able to remove this limit at the
    expense of backing off one optimization in certain circumstances. Normally,
    when pcre_exec() would call its internal match() function recursively and
    immediately return the result unconditionally, it uses a "tail recursion"
    feature to save stack. However, when a subpattern that can match an empty
    string has an unlimited repetition quantifier, it no longer makes this
    optimization. That gives it a stack frame in which to save the data for
    checking that an empty string has been matched. Previously this was taken
    from the 1000-entry workspace that had been reserved. So now there is no
    explicit limit, but more stack is used.

 8. Applied Daniel's patches to solve problems with the import/export magic
    syntax that is required for Windows, and which was going wrong for the
    pcreposix and pcrecpp parts of the library. These were overlooked when this
    problem was solved for the main library.

 9. There were some crude static tests to avoid integer overflow when computing
    the size of patterns that contain repeated groups with explicit upper
    limits. As the maximum quantifier is 65535, the maximum group length was
    set at 30,000 so that the product of these two numbers did not overflow a
    32-bit integer. However, it turns out that people want to use groups that
    are longer than 30,000 bytes (though not repeat them that many times).
    Change 7.0/17 (the refactoring of the way the pattern size is computed) has
    made it possible to implement the integer overflow checks in a much more
    dynamic way, which I have now done. The artificial limitation on group
    length has been removed - we now have only the limit on the total length of
    the compiled pattern, which depends on the LINK_SIZE setting.

10. Fixed a bug in the documentation for get/copy named substring when
    duplicate names are permitted. If none of the named substrings are set, the
    functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
    empty string.

11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
    instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
    because the ] is interpreted as the first data character and the
    terminating ] is not found. PCRE has been made compatible with Perl in this
    regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
    cause memory overwriting.

10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
    string has been matched (to stop an infinite loop). It was not recognizing
    a conditional subpattern that could match an empty string if that
    subpattern was within another subpattern. For example, it looped when
    trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
    condition was not nested. This bug has been fixed.

12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
    past the start of the subject in the presence of bytes with the top bit
    set, for example "\x8aBCD".

13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
    (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).

14. Optimized (?!) to (*FAIL).

15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
    This restricts code points to be within the range 0 to 0x10FFFF, excluding
    the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
    full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
    does: it's just the validity check that is more restrictive.

16. Inserted checks for integer overflows during escape sequence (backslash)
    processing, and also fixed erroneous offset values for syntax errors during
    backslash processing.

17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
    for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".

18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
    caused an overrun.

19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
    something other than just ASCII characters) inside a group that had an
    unlimited repeat caused a loop at compile time (while checking to see
    whether the group could match an empty string).

20. Debugging a pattern containing \p or \P could cause a crash. For example,
    [\P{Any}] did so. (Error in the code for printing property names.)

21. An orphan \E inside a character class could cause a crash.

22. A repeated capturing bracket such as (A)? could cause a wild memory
    reference during compilation.

23. There are several functions in pcre_compile() that scan along a compiled
    expression for various reasons (e.g. to see if it's fixed length for look
    behind). There were bugs in these functions when a repeated \p or \P was
    present in the pattern. These operators have additional parameters compared
    with \d, etc, and these were not being taken into account when moving along
    the compiled data. Specifically:

    (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed

    (b) An item such as \pL+ within a repeated group could cause crashes or

    (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
        "reference to non-existent subpattern" error.

    (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.

24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
    characters were involved (for example /\S{2}/8g with "A\x{a3}BC").

25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.

26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
    character were causing crashes (broken optimization).

27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
    \p or \P) caused a compile-time loop.

28. More problems have arisen in unanchored patterns when CRLF is a valid line
    break. For example, the unstudied pattern [\r\n]A does not match the string
    "\r\nA" because change 7.0/46 below moves the current point on by two
    characters after failing to match at the start. However, the pattern \nA
    *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
    the same is true. There doesn't seem any very clean way out of this, but
    what I have chosen to do makes the common cases work: PCRE now takes note
    of whether there can be an explicit match for \r or \n anywhere in the
    pattern, and if so, 7.0/46 no longer applies. As part of this change,
    there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
    pattern has explicit CR or LF references.

29. Added (*CR) etc for changing newline setting at start of pattern.

Version 7.2 19-Jun-07

 1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
    which is apparently normally available under Windows.

 2. Re-jig the pcregrep tests with different newline settings in an attempt
    to make them independent of the local environment's newline setting.

 3. Add code to configure.ac to remove -g from the CFLAGS default settings.

 4. Some of the "internals" tests were previously cut out when the link size
    was not 2, because the output contained actual offsets. The recent new
    "Z" feature of pcretest means that these can be cut out, making the tests
    usable with all link sizes.

 5. Implemented Stan Switzer's goto replacement for longjmp() when not using
    stack recursion. This gives a massive performance boost under BSD, but just
    a small improvement under Linux. However, it saves one field in the frame
    in all cases.

 6. Added more features from the forthcoming Perl 5.10:

    (a) (?-n) (where n is a string of digits) is a relative subroutine or
        recursion call. It refers to the nth most recently opened parentheses.

    (b) (?+n) is also a relative subroutine call; it refers to the nth next
        to be opened parentheses.

    (c) Conditions that refer to capturing parentheses can be specified
        relatively, for example, (?(-2)... or (?(+3)...

    (d) \K resets the start of the current match so that everything before
        is not part of it.

    (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).

    (f) \g{name} is another synonym - part of Perl 5.10's unification of
        reference syntax.

    (g) (?| introduces a group in which the numbering of parentheses in each
        alternative starts with the same number.

    (h) \h, \H, \v, and \V match horizontal and vertical whitespace.

 7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and

 8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
    terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
    for detecting groups that can match an empty string.

 9. A pattern with a very large number of alternatives (more than several
    hundred) was running out of internal workspace during the pre-compile
    phase, where pcre_compile() figures out how much memory will be needed. A
    bit of new cunning has reduced the workspace needed for groups with
    alternatives. The 1000-alternative test pattern now uses 12 bytes of
    workspace instead of running out of the 4096 that are available.

10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.

11. Applied patch from Google to remove an optimization that didn't quite work.
    The report of the bug said:

      pcrecpp::RE("a*").FullMatch("aaa") matches, while
      pcrecpp::RE("a*?").FullMatch("aaa") does not, and
      pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.

12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
    it matched the wrong number of bytes.

Version 7.1 24-Apr-07

 1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
    that is more "standard", making use of automake and other Autotools. There
    is some re-arrangement of the files and adjustment of comments consequent
    on this.

 2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
    for recursive directory scanning broke on some systems because the files
    are not scanned in any specific order and on different systems the order
    was different. A call to "sort" has been inserted into RunGrepTest for the
    approprate test as a short-term fix. In the longer term there may be an

 3. I had an email from Eric Raymond about problems translating some of PCRE's
    man pages to HTML (despite the fact that I distribute HTML pages, some
    people do their own conversions for various reasons). The problems
    concerned the use of low-level troff macros .br and .in. I have therefore
    removed all such uses from the man pages (some were redundant, some could
    be replaced by .nf/.fi pairs). The 132html script that I use to generate
    HTML has been updated to handle .nf/.fi and to complain if it encounters
    .br or .in.

 4. Updated comments in configure.ac that get placed in config.h.in and also
    arranged for config.h to be included in the distribution, with the name
    config.h.generic, for the benefit of those who have to compile without
    Autotools (compare pcre.h, which is now distributed as pcre.h.generic).

 5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
    Weber: (1) pcre_internal.h was missing some function renames; (2) updated
    makevp.bat for the current PCRE, using the additional files
    makevp_c.txt, makevp_l.txt, and pcregexp.pas.

 6. A Windows user reported a minor discrepancy with test 2, which turned out
    to be caused by a trailing space on an input line that had got lost in his
    copy. The trailing space was an accident, so I've just removed it.

 7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
    that is needed.

 8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
    as "const" (a) because they are and (b) because it helps the PHP
    maintainers who have recently made a script to detect big data structures
    in the php code that should be moved to the .rodata section. I remembered
    to update Builducptable as well, so it won't revert if ucptable.h is ever

 9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
    pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
    order to be able to cut out the UTF-8 tables in the latter when UTF-8
    support is not required. This saves 1.5-2K of code, which is important in
    some applications.

    Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
    so as not to refer to the tables, even though these functions will never be
    called when UTF-8 support is disabled. Otherwise there are problems with a
    shared library.

10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:

    (a) It was defining its arguments as char * instead of void *.

    (b) It was assuming that all moves were upwards in memory; this was true
        a long time ago when I wrote it, but is no longer the case.

    The emulated memove() is provided for those environments that have neither
    memmove() nor bcopy(). I didn't think anyone used it these days, but that
    is clearly not the case, as these two bugs were recently reported.

11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
    and Detrail to create the HTML documentation, the .txt form of the man
    pages, and it removes trailing spaces from listed files. It also creates
    pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
    case, it wraps all the #defines with #ifndefs. This script should be run
    before "make dist".

12. Fixed two fairly obscure bugs concerned with quantified caseless matching
    with Unicode property support.

    (a) For a maximizing quantifier, if the two different cases of the
        character were of different lengths in their UTF-8 codings (there are
        some cases like this - I found 11), and the matching function had to
        back up over a mixture of the two cases, it incorrectly assumed they
        were both the same length.

    (b) When PCRE was configured to use the heap rather than the stack for
        recursion during matching, it was not correctly preserving the data for
        the other case of a UTF-8 character when checking ahead for a match
        while processing a minimizing repeat. If the check also involved
        matching a wide character, but failed, corruption could cause an
        erroneous result when trying to check for a repeat of the original

13. Some tidying changes to the testing mechanism:

    (a) The RunTest script now detects the internal link size and whether there
        is UTF-8 and UCP support by running ./pcretest -C instead of relying on
        values substituted by "configure". (The RunGrepTest script already did
        this for UTF-8.) The configure.ac script no longer substitutes the
        relevant variables.

    (b) The debugging options /B and /D in pcretest show the compiled bytecode
        with length and offset values. This means that the output is different
        for different internal link sizes. Test 2 is skipped for link sizes
        other than 2 because of this, bypassing the problem. Unfortunately,
        there was also a test in test 3 (the locale tests) that used /B and
        failed for link sizes other than 2. Rather than cut the whole test out,
        I have added a new /Z option to pcretest that replaces the length and
        offset values with spaces. This is now used to make test 3 independent
        of link size. (Test 2 will be tidied up later.)

14. If erroroffset was passed as NULL to pcre_compile, it provoked a
    segmentation fault instead of returning the appropriate error message.

15. In multiline mode when the newline sequence was set to "any", the pattern
    ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
    This doesn't seem right; it now treats the CRLF combination as the line
    ending, and so does not match in that case. It's only a pattern such as ^$
    that would hit this one: something like ^ABC$ would have failed after \r
    and then tried again after \r\n.

16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
    in an attempt to make files that differ only in their line terminators
    compare equal. This works on Linux.

17. Under certain error circumstances pcregrep might try to free random memory
    as it exited. This is now fixed, thanks to valgrind.

19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
    "abc\r\n\r\n", it found an unwanted second match after the second \r. This
    was because its rules for how to advance for /g after matching an empty
    string at the end of a line did not allow for this case. They now check for
    it specially.

20. pcretest is supposed to handle patterns and data of any length, by
    extending its buffers when necessary. It was getting this wrong when the
    buffer for a data line had to be extended.

21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
    CRLF as a newline sequence.

22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
    out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
    I have nevertheless tidied it up.

23. Added some casts to kill warnings from HP-UX ia64 compiler.

24. Added a man page for pcre-config.

Version 7.0 19-Dec-06

 1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
    moving to gcc 4.1.1.

 2. The -S option for pcretest uses setrlimit(); I had omitted to #include
    sys/time.h, which is documented as needed for this function. It doesn't
    seem to matter on Linux, but it showed up on some releases of OS X.

 3. It seems that there are systems where bytes whose values are greater than
    127 match isprint() in the "C" locale. The "C" locale should be the
    default when a C program starts up. In most systems, only ASCII printing
    characters match isprint(). This difference caused the output from pcretest
    to vary, making some of the tests fail. I have changed pcretest so that:

    (a) When it is outputting text in the compiled version of a pattern, bytes
        other than 32-126 are always shown as hex escapes.

    (b) When it is outputting text that is a matched part of a subject string,
        it does the same, unless a different locale has been set for the match
        (using the /L modifier). In this case, it uses isprint() to decide.

 4. Fixed a major bug that caused incorrect computation of the amount of memory
    required for a compiled pattern when options that changed within the
    pattern affected the logic of the preliminary scan that determines the
    length. The relevant options are -x, and -i in UTF-8 mode. The result was
    that the computed length was too small. The symptoms of this bug were
    either the PCRE error "internal error: code overflow" from pcre_compile(),
    or a glibc crash with a message such as "pcretest: free(): invalid next
    size (fast)". Examples of patterns that provoked this bug (shown in
    pcretest format) are:

      /(?-x: )/x
      /(?x)(?-x: \s*#\s*)/

    HOWEVER: Change 17 below makes this fix obsolete as the memory computation
    is now done differently.

 5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
    wrapper classes; (b) implement a new function in the C++ scanner that is
    more efficient than the old way of doing things because it avoids levels of
    recursion in the regex matching; (c) add a paragraph to the documentation
    for the FullMatch() function.

 6. The escape sequence \n was being treated as whatever was defined as
    "newline". Not only was this contrary to the documentation, which states
    that \n is character 10 (hex 0A), but it also went horribly wrong when
    "newline" was defined as CRLF. This has been fixed.

 7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
    was being set to -1 for the "end of line" case (supposedly a value that no
    character can have). Though this value is never used (the check for end of
    line is "zero bytes in current character"), it caused compiler complaints.
    I've changed it to 0xffffffff.

 8. In pcre_version.c, the version string was being built by a sequence of
    C macros that, in the event of PCRE_PRERELEASE being defined as an empty
    string (as it is for production releases) called a macro with an empty
    argument. The C standard says the result of this is undefined. The gcc
    compiler treats it as an empty string (which was what was wanted) but it is
    reported that Visual C gives an error. The source has been hacked around to
    avoid this problem.

 9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
    builds of pcretest, and changed the call to _setmode() to use _O_BINARY
    instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
    of them did).

10. Originally, pcretest opened its input and output without "b"; then I was
    told that "b" was needed in some environments, so it was added for release
    5.0 to both the input and output. (It makes no difference on Unix-like
    systems.) Later I was told that it is wrong for the input on Windows. I've
    now abstracted the modes into two macros, to make it easier to fiddle with
    them, and removed "b" from the input mode under Windows.

11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.

12. Added -help and --help to pcretest as an official way of being reminded
    of the options.

13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
    and pcrecpp.cc because they annoy compilers at high warning levels.

14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.

15. Fixed an occurrence of == in configure.ac that should have been = (shell
    scripts are not C programs :-) and which was not noticed because it works
    on Linux.

16. pcretest is supposed to handle any length of pattern and data line (as one
    line or as a continued sequence of lines) by extending its input buffer if
    necessary. This feature was broken for very long pattern lines, leading to
    a string of junk being passed to pcre_compile() if the pattern was longer
    than about 50K.

17. I have done a major re-factoring of the way pcre_compile() computes the
    amount of memory needed for a compiled pattern. Previously, there was code
    that made a preliminary scan of the pattern in order to do this. That was
    OK when PCRE was new, but as the facilities have expanded, it has become
    harder and harder to keep it in step with the real compile phase, and there
    have been a number of bugs (see for example, 4 above). I have now found a
    cunning way of running the real compile function in a "fake" mode that
    enables it to compute how much memory it would need, while actually only
    ever using a few hundred bytes of working memory and without too many
    tests of the mode. This should make future maintenance and development
    easier. A side effect of this work is that the limit of 200 on the nesting
    depth of parentheses has been removed (though this was never a serious
    limitation, I suspect). However, there is a downside: pcre_compile() now
    runs more slowly than before (30% or more, depending on the pattern). I
    hope this isn't a big issue. There is no effect on runtime performance.

18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
    newline (only possible for the last line of a file) and it was a
    pattern that set a locale (followed by /Lsomething), pcretest crashed.

19. Added additional timing features to pcretest. (1) The -tm option now times
    matching only, not compiling. (2) Both -t and -tm can be followed, as a
    separate command line item, by a number that specifies the number of
    repeats to use when timing. The default is 50000; this gives better
    precision, but takes uncomfortably long for very large patterns.

20. Extended pcre_study() to be more clever in cases where a branch of a
    subpattern has no definite first character. For example, (a*|b*)[cd] would
    previously give no result from pcre_study(). Now it recognizes that the
    first character must be a, b, c, or d.

21. There was an incorrect error "recursive call could loop indefinitely" if
    a subpattern (or the entire pattern) that was being tested for matching an
    empty string contained only one non-empty item after a nested subpattern.
    For example, the pattern (?>\x{100}*)\d(?R) provoked this error
    incorrectly, because the \d was being skipped in the check.

22. The pcretest program now has a new pattern option /B and a command line
    option -b, which is equivalent to adding /B to every pattern. This causes
    it to show the compiled bytecode, without the additional information that
    -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
    is the same as /B/I).

23. A new optimization is now able automatically to treat some sequences such
    as a*b as a*+b. More specifically, if something simple (such as a character
    or a simple class like \d) has an unlimited quantifier, and is followed by
    something that cannot possibly match the quantified thing, the quantifier
    is automatically "possessified".

24. A recursive reference to a subpattern whose number was greater than 39
    went wrong under certain circumstances in UTF-8 mode. This bug could also
    have affected the operation of pcre_study().

25. Realized that a little bit of performance could be had by replacing
    (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.

26. Timing data from pcretest is now shown to 4 decimal places instead of 3.

27. Possessive quantifiers such as a++ were previously implemented by turning
    them into atomic groups such as ($>a+). Now they have their own opcodes,
    which improves performance. This includes the automatically created ones
    from 23 above.

28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
    lookahead was broken if it was not anchored. PCRE was mistakenly expecting
    the first matched character to be a colon. This applied both to named and
    numbered groups.

29. The ucpinternal.h header file was missing its idempotency #ifdef.

30. I was sent a "project" file called libpcre.a.dev which I understand makes
    building PCRE on Windows easier, so I have included it in the distribution.

31. There is now a check in pcretest against a ridiculously large number being
    returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
    loop, the loop is abandoned.

32. Forward references to subpatterns in conditions such as (?(2)...) where
    subpattern 2 is defined later cause pcre_compile() to search forwards in
    the pattern for the relevant set of parentheses. This search went wrong
    when there were unescaped parentheses in a character class, parentheses
    escaped with \Q...\E, or parentheses in a #-comment in /x mode.

33. "Subroutine" calls and backreferences were previously restricted to
    referencing subpatterns earlier in the regex. This restriction has now
    been removed.

34. Added a number of extra features that are going to be in Perl 5.10. On the
    whole, these are just syntactic alternatives for features that PCRE had
    previously implemented using the Python syntax or my own invention. The
    other formats are all retained for compatibility.

    (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
        as (?P<name>...). The new forms, as well as being in Perl 5.10, are
        also .NET compatible.

    (b) A recursion or subroutine call to a named group can now be defined as
        (?&name) as well as (?P>name).

    (c) A backreference to a named group can now be defined as \k<name> or
        \k'name' as well as (?P=name). The new forms, as well as being in Perl
        5.10, are also .NET compatible.

    (d) A conditional reference to a named group can now use the syntax
        (?(<name>) or (?('name') as well as (?(name).

    (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
        groups (named and numbered) that are never evaluated inline, but can be
        called as "subroutines" from elsewhere. In effect, the DEFINE condition
        is always false. There may be only one alternative in such a group.

    (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
        as the simple (?(R). The condition is true only if the most recent
        recursion is that of the given number or name. It does not search out
        through the entire recursion stack.

    (g) The escape \gN or \g{N} has been added, where N is a positive or
        negative number, specifying an absolute or relative reference.

35. Tidied to get rid of some further signed/unsigned compiler warnings and
    some "unreachable code" warnings.

36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
    things, this adds five new scripts.

37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
    There were also incompatibilities regarding the handling of \Q..\E inside
    character classes, for example with patterns like [\Qa\E-\Qz\E] where the
    hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.

38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
    matches an empty string, and forcibly breaks the loop. There were bugs in
    this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
    against  aaaa  the result was just "a" rather than "aaaa", for example. Two
    separate and independent bugs (that affected different cases) have been

39. Refactored the code to abolish the use of different opcodes for small
    capturing bracket numbers. This is a tidy that I avoided doing when I
    removed the limit on the number of capturing brackets for 3.5 back in 2001.
    The new approach is not only tidier, it makes it possible to reduce the
    memory needed to fix the previous bug (38).

40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
    sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
    processing dot, circumflex, or dollar metacharacters, or #-comments in /x

41. Add \R to match any Unicode newline sequence, as suggested in the Unicode

42. Applied patch, originally from Ari Pollak, modified by Google, to allow
    copy construction and assignment in the C++ wrapper.

43. Updated pcregrep to support "--newline=any". In the process, I fixed a
    couple of bugs that could have given wrong results in the "--newline=crlf"

44. Added a number of casts and did some reorganization of signed/unsigned int
    variables following suggestions from Dair Grant. Also renamed the variable
    "this" as "item" because it is a C++ keyword.

45. Arranged for dftables to add

      #include "pcre_internal.h"

    to pcre_chartables.c because without it, gcc 4.x may remove the array
    definition from the final binary if PCRE is built into a static library and
    dead code stripping is activated.

46. For an unanchored pattern, if a match attempt fails at the start of a
    newline sequence, and the newline setting is CRLF or ANY, and the next two
    characters are CRLF, advance by two characters instead of one.

Version 6.7 04-Jul-06

 1. In order to handle tests when input lines are enormously long, pcretest has
    been re-factored so that it automatically extends its buffers when
    necessary. The code is crude, but this _is_ just a test program. The
    default size has been increased from 32K to 50K.

 2. The code in pcre_study() was using the value of the re argument before
    testing it for NULL. (Of course, in any sensible call of the function, it
    won't be NULL.)

 3. The memmove() emulation function in pcre_internal.h, which is used on
    systems that lack both memmove() and bcopy() - that is, hardly ever -
    was missing a "static" storage class specifier.

 4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
    containing an extended class (one that cannot be represented by a bitmap
    because it contains high-valued characters or Unicode property items, e.g.
    [\pZ]). Almost always one would set UTF-8 mode when processing such a
    pattern, but PCRE should not loop if you do not (it no longer does).
    [Detail: two cases were found: (a) a repeated subpattern containing an
    extended class; (b) a recursive reference to a subpattern that followed a
    previous extended class. It wasn't skipping over the extended class
    correctly when UTF-8 mode was not set.]

 5. A negated single-character class was not being recognized as fixed-length
    in lookbehind assertions such as (?<=[^f]), leading to an incorrect
    compile error "lookbehind assertion is not fixed length".

 6. The RunPerlTest auxiliary script was showing an unexpected difference
    between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
    write a Perl script that can interpret lines of an input file either as
    byte characters or as UTF-8, which is what "perltest" was being required to
    do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
    can't do is switch easily at run time between having the "use utf8;" pragma
    or not. In the end, I fudged it by using the RunPerlTest script to insert
    "use utf8;" explicitly for the UTF-8 tests.

 7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
    the end of the subject string, contrary to the documentation and to what
    Perl does. This was true of both matching functions. Now it matches only at
    the start of the subject and immediately after *internal* newlines.

 8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
    a pointer to an int instead of a pointer to an unsigned long int. This
    caused problems on 64-bit systems.

 9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
    instance of the 'standard' template library not being so standard".

10. There was no check on the number of named subpatterns nor the maximum
    length of a subpattern name. The product of these values is used to compute
    the size of the memory block for a compiled pattern. By supplying a very
    long subpattern name and a large number of named subpatterns, the size
    computation could be caused to overflow. This is now prevented by limiting
    the length of names to 32 characters, and the number of named subpatterns
    to 10,000.

11. Subpatterns that are repeated with specific counts have to be replicated in
    the compiled pattern. The size of memory for this was computed from the
    length of the subpattern and the repeat count. The latter is limited to
    65535, but there was no limit on the former, meaning that integer overflow
    could in principle occur. The compiled length of a repeated subpattern is
    now limited to 30,000 bytes in order to prevent this.

12. Added the optional facility to have named substrings with the same name.

13. Added the ability to use a named substring as a condition, using the
    Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
    are numbers (not recommended). Forward references are permitted.

14. Added forward references in named backreferences (if you see what I mean).

15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
    pattern could run off the end of the subject. For example, the pattern
    "(?s)(.{1,5})"8 did this with the subject "ab".

16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
    PCRE_CASELESS was set when matching characters that were quantified with ?
    or *.

17. A character class other than a single negated character that had a minimum
    but no maximum quantifier - for example [ab]{6,} - was not handled
    correctly by pce_dfa_exec(). It would match only one character.

18. A valid (though odd) pattern that looked like a POSIX character
    class but used an invalid character after [ (for example [[,abc,]]) caused
    pcre_compile() to give the error "Failed: internal error: code overflow" or
    in some cases to crash with a glibc free() error. This could even happen if
    the pattern terminated after [[ but there just happened to be a sequence of
    letters, a binary zero, and a closing ] in the memory that followed.

19. Perl's treatment of octal escapes in the range \400 to \777 has changed
    over the years. Originally (before any Unicode support), just the bottom 8
    bits were taken. Thus, for example, \500 really meant \100. Nowadays the
    output from "man perlunicode" includes this:

      The regular expression compiler produces polymorphic opcodes.  That
      is, the pattern adapts to the data and automatically switches to
      the Unicode character scheme when presented with Unicode data--or
      instead uses a traditional byte scheme when presented with byte

    Sadly, a wide octal escape does not cause a switch, and in a string with
    no other multibyte characters, these octal escapes are treated as before.
    Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
    /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
    Unicode string.

    I have not perpetrated such confusion in PCRE. Up till now, it took just
    the bottom 8 bits, as in old Perl. I have now made octal escapes with
    values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
    translate to the appropriate multibyte character.

29. Applied some refactoring to reduce the number of warnings from Microsoft
    and Borland compilers. This has included removing the fudge introduced
    seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
    a warning about an unused variable.

21. PCRE has not included VT (character 0x0b) in the set of whitespace
    characters since release 4.0, because Perl (from release 5.004) does not.
    [Or at least, is documented not to: some releases seem to be in conflict
    with the documentation.] However, when a pattern was studied with
    pcre_study() and all its branches started with \s, PCRE still included VT
    as a possible starting character. Of course, this did no harm; it just
    caused an unnecessary match attempt.

22. Removed a now-redundant internal flag bit that recorded the fact that case
    dependency changed within the pattern. This was once needed for "required
    byte" processing, but is no longer used. This recovers a now-scarce options
    bit. Also moved the least significant internal flag bit to the most-
    significant bit of the word, which was not previously used (hangover from
    the days when it was an int rather than a uint) to free up another bit for
    the future.

23. Added support for CRLF line endings as well as CR and LF. As well as the
    default being selectable at build time, it can now be changed at runtime
    via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
    specify that it is scanning data with non-default line endings.

24. Changed the definition of CXXLINK to make it agree with the definition of
    LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.

25. Applied Ian Taylor's patches to avoid using another stack frame for tail
    recursions. This makes a big different to stack usage for some patterns.

26. If a subpattern containing a named recursion or subroutine reference such
    as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
    the space required for the compiled pattern went wrong and gave too small a
    value. Depending on the environment, this could lead to "Failed: internal
    error: code overflow at offset 49" or "glibc detected double free or
    corruption" errors.

27. Applied patches from Google (a) to support the new newline modes and (b) to
    advance over multibyte UTF-8 characters in GlobalReplace.

28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
    difference for some implementation of PCRE in some Windows version.

29. Added some extra testing facilities to pcretest:

    \q<number>   in a data line sets the "match limit" value
    \Q<number>   in a data line sets the "match recursion limt" value
    -S <number>  sets the stack size, where <number> is in megabytes

    The -S option isn't available for Windows.

Version 6.6 06-Feb-06

 1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
    in pcreposix.h. I have copied the definition from pcre.h.

 2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
    because pcre.h is no longer a built file.

 3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
    not normally included in the compiled code.

Version 6.5 01-Feb-06

 1. When using the partial match feature with pcre_dfa_exec(), it was not
    anchoring the second and subsequent partial matches at the new starting
    point. This could lead to incorrect results. For example, with the pattern
    /1234/, partially matching against "123" and then "a4" gave a match.

 2. Changes to pcregrep:

    (a) All non-match returns from pcre_exec() were being treated as failures
        to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
        error message is output. Some extra information is given for the
        probably the only errors that are likely to be caused by users (by
        specifying a regex that has nested indefinite repeats, for instance).
        If there are more than 20 of these errors, pcregrep is abandoned.

    (b) A binary zero was treated as data while matching, but terminated the
        output line if it was written out. This has been fixed: binary zeroes
        are now no different to any other data bytes.

    (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
        used to set a locale for matching. The --locale=xxxx long option has
        been added (no short equivalent) to specify a locale explicitly on the
        pcregrep command, overriding the environment variables.

    (d) When -B was used with -n, some line numbers in the output were one less
        than they should have been.

    (e) Added the -o (--only-matching) option.

    (f) If -A or -C was used with -c (count only), some lines of context were
        accidentally printed for the final match.

    (g) Added the -H (--with-filename) option.

    (h) The combination of options -rh failed to suppress file names for files
        that were found from directory arguments.

    (i) Added the -D (--devices) and -d (--directories) options.

    (j) Added the -F (--fixed-strings) option.

    (k) Allow "-" to be used as a file name for -f as well as for a data file.

    (l) Added the --colo(u)r option.

    (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
        is not present by default.

 3. A nasty bug was discovered in the handling of recursive patterns, that is,
    items such as (?R) or (?1), when the recursion could match a number of
    alternatives. If it matched one of the alternatives, but subsequently,
    outside the recursion, there was a failure, the code tried to back up into
    the recursion. However, because of the way PCRE is implemented, this is not
    possible, and the result was an incorrect result from the match.

    In order to prevent this happening, the specification of recursion has
    been changed so that all such subpatterns are automatically treated as
    atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).

 4. I had overlooked the fact that, in some locales, there are characters for
    which isalpha() is true but neither isupper() nor islower() are true. In
    the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
    and ordfeminine) are like this. This affected the treatment of \w and \W
    when they appeared in character classes, but not when they appeared outside
    a character class. The bit map for "word" characters is now created
    separately from the results of isalnum() instead of just taking it from the
    upper, lower, and digit maps. (Plus the underscore character, of course.)

 5. The above bug also affected the handling of POSIX character classes such as
    [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
    permanent tables. Instead, the bit maps for such a class were previously
    created as the appropriate unions of the upper, lower, and digit bitmaps.
    Now they are created by subtraction from the [[:word:]] class, which has
    its own bitmap.

 6. The [[:blank:]] character class matches horizontal, but not vertical space.
    It is created by subtracting the vertical space characters (\x09, \x0a,
    \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
    subtraction was done in the overall bitmap for a character class, meaning
    that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
    be recognized. This bug has been fixed.

 7. Patches from the folks at Google:

      (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
      real life, but is still worth protecting against".

      (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
      regular expressions".

      (c) pcre_scanner.cc: avoid use of std::count() because not all systems
      have it.

      (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
      "configure" and the latter not, in order to fix a problem somebody had
      with compiling the Arg class on HP-UX.

      (e) Improve the error-handling of the C++ wrapper a little bit.

      (f) New tests for checking recursion limiting.

 8. The pcre_memmove() function, which is used only if the environment does not
    have a standard memmove() function (and is therefore rarely compiled),
    contained two bugs: (a) use of int instead of size_t, and (b) it was not
    returning a result (though PCRE never actually uses the result).

 9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
    large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
    returned instead of calling malloc() with an overflowing number that would
    most likely cause subsequent chaos.

10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.

11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
    with this option is matched, the nmatch and pmatch options of regexec() are

12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
    provided in case anyone wants to the the POSIX interface with UTF-8

13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
    C++ linking (needed for some HP-UX environments).

14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
    (unused parameter) and in the pcre_printint() function (omitted "default"
    switch label when the default is to do nothing).

15. Added some code to make it possible, when PCRE is compiled as a C++
    library, to replace subject pointers for pcre_exec() with a smart pointer
    class, thus making it possible to process discontinuous strings.

16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
    much the same function. They were added by different people who were trying
    to make PCRE easy to compile on non-Unix systems. It has been suggested
    that PCRE_EXPORT be abolished now that there is more automatic apparatus
    for compiling on Windows systems. I have therefore replaced it with
    PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
    defaults to "extern" for C or "extern C" for C++, which works fine on
    Unix-like systems. It is now possible to override the value of PCRE_DATA_
    SCOPE with something explicit in config.h. In addition:

    (a) pcreposix.h still had just "extern" instead of either of these macros;
        I have replaced it with PCRE_DATA_SCOPE.

    (b) Functions such as _pcre_xclass(), which are internal to the library,
        but external in the C sense, all had PCRE_EXPORT in their definitions.
        This is apparently wrong for the Windows case, so I have removed it.
        (It makes no difference on Unix-like systems.)

17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
    of recursive calls to match(). This is different to MATCH_LIMIT because
    that limits the total number of calls to match(), not all of which increase
    the depth of recursion. Limiting the recursion depth limits the amount of
    stack (or heap if NO_RECURSE is set) that is used. The default can be set
    when PCRE is compiled, and changed at run time. A patch from Google adds
    this functionality to the C++ interface.

18. Changes to the handling of Unicode character properties:

    (a) Updated the table to Unicode 4.1.0.

    (b) Recognize characters that are not in the table as "Cn" (undefined).

    (c) I revised the way the table is implemented to a much improved format
        which includes recognition of ranges. It now supports the ranges that
        are defined in UnicodeData.txt, and it also amalgamates other
        characters into ranges. This has reduced the number of entries in the
        table from around 16,000 to around 3,000, thus reducing its size
        considerably. I realized I did not need to use a tree structure after
        all - a binary chop search is just as efficient. Having reduced the
        number of entries, I extended their size from 6 bytes to 8 bytes to
        allow for more data.

    (d) Added support for Unicode script names via properties such as \p{Han}.

19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
    matching that character.

20. When matching a repeated Unicode property with a minimum greater than zero,
    (for example \pL{2,}), PCRE could look past the end of the subject if it
    reached it while seeking the minimum number of characters. This could
    happen only if some of the characters were more than one byte long, because
    there is a check for at least the minimum number of bytes.

21. Refactored the implementation of \p and \P so as to be more general, to
    allow for more different types of property in future. This has changed the
    compiled form incompatibly. Anybody with saved compiled patterns that use
    \p or \P will have to recompile them.

22. Added "Any" and "L&" to the supported property types.

23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
    but give a compile time error if the value is greater than 0xff.

24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
    accidentally not being installed or uninstalled.

25. The pcre.h file was built from pcre.h.in, but the only changes that were
    made were to insert the current release number. This seemed silly, because
    it made things harder for people building PCRE on systems that don't run
    "configure". I have turned pcre.h into a distributed file, no longer built
    by "configure", with the version identification directly included. There is
    no longer a pcre.h.in file.

    However, this change necessitated a change to the pcre-config script as
    well. It is built from pcre-config.in, and one of the substitutions was the
    release number. I have updated configure.ac so that ./configure now finds
    the release number by grepping pcre.h.

26. Added the ability to run the tests under valgrind.

Version 6.4 05-Sep-05

 1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
    "--" to be printed when multiple files were scanned, even when none of the
    -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
    consider it to be a bug, and have restored the previous behaviour.

 2. A couple of code tidies to get rid of compiler warnings.

 3. The pcretest program used to cheat by referring to symbols in the library
    whose names begin with _pcre_. These are internal symbols that are not
    really supposed to be visible externally, and in some environments it is
    possible to suppress them. The cheating is now confined to including
    certain files from the library's source, which is a bit cleaner.

 4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
    file's purpose clearer.

 5. Reorganized pcre_ucp_findchar().

Version 6.3 15-Aug-05

 1. The file libpcre.pc.in did not have general read permission in the tarball.

 2. There were some problems when building without C++ support:

    (a) If C++ support was not built, "make install" and "make test" still
        tried to test it.

    (b) There were problems when the value of CXX was explicitly set. Some
        changes have been made to try to fix these, and ...

    (c) --disable-cpp can now be used to explicitly disable C++ support.

    (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
        backslash in a target when C++ was disabled. This confuses some
        versions of "make", apparently. Using an intermediate variable solves
        this. (Same for CPP_LOBJ.)

 3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
    (non-Windows) now includes $(CFLAGS) because these flags are sometimes
    necessary on certain architectures.

 4. Added a setting of -export-symbols-regex to the link command to remove
    those symbols that are exported in the C sense, but actually are local
    within the library, and not documented. Their names all begin with
    "_pcre_". This is not a perfect job, because (a) we have to except some
    symbols that pcretest ("illegally") uses, and (b) the facility isn't always
    available (and never for static libraries). I have made a note to try to
    find a way round (a) in the future.

Version 6.2 01-Aug-05

 1. There was no test for integer overflow of quantifier values. A construction
    such as {1111111111111111} would give undefined results. What is worse, if
    a minimum quantifier for a parenthesized subpattern overflowed and became
    negative, the calculation of the memory size went wrong. This could have
    led to memory overwriting.

 2. Building PCRE using VPATH was broken. Hopefully it is now fixed.

 3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
    operating environments where this matters.

 4. Applied Giuseppe Maxia's patch to add additional features for controlling
    PCRE options from within the C++ wrapper.

 5. Named capturing subpatterns were not being correctly counted when a pattern
    was compiled. This caused two problems: (a) If there were more than 100
    such subpatterns, the calculation of the memory needed for the whole
    compiled pattern went wrong, leading to an overflow error. (b) Numerical
    back references of the form \12, where the number was greater than 9, were
    not recognized as back references, even though there were sufficient
    previous subpatterns.

 6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
    versions of gcc, e.g. 2.95.4.

Version 6.1 21-Jun-05

 1. There was one reference to the variable "posix" in pcretest.c that was not
    surrounded by "#if !defined NOPOSIX".

 2. Make it possible to compile pcretest without DFA support, UTF8 support, or
    the cross-check on the old pcre_info() function, for the benefit of the
    cut-down version of PCRE that is currently imported into Exim.

 3. A (silly) pattern starting with (?i)(?-i) caused an internal space
    allocation error. I've done the easy fix, which wastes 2 bytes for sensible
    patterns that start (?i) but I don't think that matters. The use of (?i) is
    just an example; this all applies to the other options as well.

 4. Since libtool seems to echo the compile commands it is issuing, the output
    from "make" can be reduced a bit by putting "@" in front of each libtool
    compile command.

 5. Patch from the folks at Google for configure.in to be a bit more thorough
    in checking for a suitable C++ installation before trying to compile the
    C++ stuff. This should fix a reported problem when a compiler was present,
    but no suitable headers.

 6. The man pages all had just "PCRE" as their title. I have changed them to
    be the relevant file name. I have also arranged that these names are
    retained in the file doc/pcre.txt, which is a concatenation in text format
    of all the man pages except the little individual ones for each function.

 7. The NON-UNIX-USE file had not been updated for the different set of source
    files that come with release 6. I also added a few comments about the C++

Version 6.0 07-Jun-05

 1. Some minor internal re-organization to help with my DFA experiments.

 2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
    didn't matter for the library itself when fully configured, but did matter
    when compiling without UCP support, or within Exim, where the ucp files are
    not imported.

 3. Refactoring of the library code to split up the various functions into
    different source modules. The addition of the new DFA matching code (see
    below) to a single monolithic source would have made it really too
    unwieldy, quite apart from causing all the code to be include in a
    statically linked application, when only some functions are used. This is
    relevant even without the DFA addition now that patterns can be compiled in
    one application and matched in another.

    The downside of splitting up is that there have to be some external
    functions and data tables that are used internally in different modules of
    the library but which are not part of the API. These have all had their
    names changed to start with "_pcre_" so that they are unlikely to clash
    with other external names.

 4. Added an alternate matching function, pcre_dfa_exec(), which matches using
    a different (DFA) algorithm. Although it is slower than the original
    function, it does have some advantages for certain types of matching

 5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
    including restarting after a partial match.

 6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
    defined when compiling for Windows was sent to me. I have put it into the
    code, though I have no means of testing or verifying it.

 7. Added the pcre_refcount() auxiliary function.

 8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
    match before or at the first newline in the subject string. In pcretest,
    the /f option on a pattern can be used to set this.

 9. A repeated \w when used in UTF-8 mode with characters greater than 256
    would behave wrongly. This has been present in PCRE since release 4.0.

10. A number of changes to the pcregrep command:

    (a) Refactored how -x works; insert ^(...)$ instead of setting
        PCRE_ANCHORED and checking the length, in preparation for adding
        something similar for -w.

    (b) Added the -w (match as a word) option.

    (c) Refactored the way lines are read and buffered so as to have more
        than one at a time available.

    (d) Implemented a pcregrep test script.

    (e) Added the -M (multiline match) option. This allows patterns to match
        over several lines of the subject. The buffering ensures that at least
        8K, or the rest of the document (whichever is the shorter) is available
        for matching (and similarly the previous 8K for lookbehind assertions).

    (f) Changed the --help output so that it now says

          -w, --word-regex(p)

        instead of two lines, one with "regex" and the other with "regexp"
        because that confused at least one person since the short forms are the
        same. (This required a bit of code, as the output is generated
        automatically from a table. It wasn't just a text change.)

    (g) -- can be used to terminate pcregrep options if the next thing isn't an
        option but starts with a hyphen. Could be a pattern or a path name
        starting with a hyphen, for instance.

    (h) "-" can be given as a file name to represent stdin.

    (i) When file names are being printed, "(standard input)" is used for
        the standard input, for compatibility with GNU grep. Previously
        "<stdin>" was used.

    (j) The option --label=xxx can be used to supply a name to be used for
        stdin when file names are being printed. There is no short form.

    (k) Re-factored the options decoding logic because we are going to add
        two more options that take data. Such options can now be given in four
        different ways, e.g. "-fname", "-f name", "--file=name", "--file name".

    (l) Added the -A, -B, and -C options for requesting that lines of context
        around matches be printed.

    (m) Added the -L option to print the names of files that do not contain
        any matching lines, that is, the complement of -l.

    (n) The return code is 2 if any file cannot be opened, but pcregrep does
        continue to scan other files.

    (o) The -s option was incorrectly implemented. For compatibility with other
        greps, it now suppresses the error message for a non-existent or non-
        accessible file (but not the return code). There is a new option called
        -q that suppresses the output of matching lines, which was what -s was
        previously doing.

    (p) Added --include and --exclude options to specify files for inclusion
        and exclusion when recursing.

11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
    Hopefully, it now does.

12. Missing cast in pcre_study().

13. Added an "uninstall" target to the makefile.

14. Replaced "extern" in the function prototypes in Makefile.in with
    "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
    world, but is set differently for Windows.

15. Added a second compiling function called pcre_compile2(). The only
    difference is that it has an extra argument, which is a pointer to an
    integer error code. When there is a compile-time failure, this is set
    non-zero, in addition to the error test pointer being set to point to an
    error message. The new argument may be NULL if no error number is required
    (but then you may as well call pcre_compile(), which is now just a
    wrapper). This facility is provided because some applications need a
    numeric error indication, but it has also enabled me to tidy up the way
    compile-time errors are handled in the POSIX wrapper.

16. Added VPATH=.libs to the makefile; this should help when building with one
    prefix path and installing with another. (Or so I'm told by someone who
    knows more about this stuff than I do.)

17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
    passes PCRE_DOTALL to the pcre_compile() function, making the "." character
    match everything, including newlines. This is not POSIX-compatible, but
    somebody wanted the feature. From pcretest it can be activated by using
    both the P and the s flags.

18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.

19. libpcre.pc was being incorrectly installed as executable.

20. A couple of places in pcretest check for end-of-line by looking for '\n';
    it now also looks for '\r' so that it will work unmodified on Windows.

21. Added Google's contributed C++ wrapper to the distribution.

22. Added some untidy missing memory free() calls in pcretest, to keep
    Electric Fence happy when testing.

Version 5.0 13-Sep-04

 1. Internal change: literal characters are no longer packed up into items
    containing multiple characters in a single byte-string. Each character
    is now matched using a separate opcode. However, there may be more than one
    byte in the character in UTF-8 mode.

 2. The pcre_callout_block structure has two new fields: pattern_position and
    next_item_length. These contain the offset in the pattern to the next match
    item, and its length, respectively.

 3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
    insertion of callouts before each pattern item. Added the /C option to
    pcretest to make use of this.

 4. On the advice of a Windows user, the lines

      #if defined(_WIN32) || defined(WIN32)
      _setmode( _fileno( stdout ), 0x8000 );
      #endif  /* defined(_WIN32) || defined(WIN32) */

    have been added to the source of pcretest. This apparently does useful
    magic in relation to line terminators.

 5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
    for the benefit of those environments where the "b" makes a difference.

 6. The icc compiler has the same options as gcc, but "configure" doesn't seem
    to know about it. I have put a hack into configure.in that adds in code
    to set GCC=yes if CC=icc. This seems to end up at a point in the
    generated configure script that is early enough to affect the setting of
    compiler options, which is what is needed, but I have no means of testing
    whether it really works. (The user who reported this had patched the
    generated configure script, which of course I cannot do.)

    LATER: After change 22 below (new libtool files), the configure script
    seems to know about icc (and also ecc). Therefore, I have commented out
    this hack in configure.in.

 7. Added support for pkg-config (2 patches were sent in).

 8. Negated POSIX character classes that used a combination of internal tables
    were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
    [[:^ascii]]. Typically, they would match almost any characters. The other
    POSIX classes were not broken in this way.

 9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
    to find the match, as PCRE was deluded into thinking that the match had to
    start at the start point or following a newline. The same bug applied to
    patterns with negative forward assertions or any backward assertions
    preceding ".*" at the start, unless the pattern required a fixed first
    character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.

10. In UTF-8 mode, when moving forwards in the subject after a failed match
    starting at the last subject character, bytes beyond the end of the subject
    string were read.

11. Renamed the variable "class" as "classbits" to make life easier for C++
    users. (Previously there was a macro definition, but it apparently wasn't

12. Added the new field "tables" to the extra data so that tables can be passed
    in at exec time, or the internal tables can be re-selected. This allows
    a compiled regex to be saved and re-used at a later time by a different
    program that might have everything at different addresses.

13. Modified the pcre-config script so that, when run on Solaris, it shows a
    -R library as well as a -L library.

14. The debugging options of pcretest (-d on the command line or D on a
    pattern) showed incorrect output for anything following an extended class
    that contained multibyte characters and which was followed by a quantifier.

15. Added optional support for general category Unicode character properties
    via the \p, \P, and \X escapes. Unicode property support implies UTF-8
    support. It adds about 90K to the size of the library. The meanings of the
    inbuilt class escapes such as \d and \s have NOT been changed.

16. Updated pcredemo.c to include calls to free() to release the memory for the
    compiled pattern.

17. The generated file chartables.c was being created in the source directory
    instead of in the building directory. This caused the build to fail if the
    source directory was different from the building directory, and was

18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
    file. No doubt somebody will tell me if they don't make sense... Also added
    Dan Mooney's comments about building on OpenVMS.

19. Added support for partial matching via the PCRE_PARTIAL option for
    pcre_exec() and the \P data escape in pcretest.

20. Extended pcretest with 3 new pattern features:

    (i)   A pattern option of the form ">rest-of-line" causes pcretest to
          write the compiled pattern to the file whose name is "rest-of-line".
          This is a straight binary dump of the data, with the saved pointer to
          the character tables forced to be NULL. The study data, if any, is
          written too. After writing, pcretest reads a new pattern.

    (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
          compiled pattern from the given file. There must not be any
          occurrences of "<" in the file name (pretty unlikely); if there are,
          pcretest will instead treat the initial "<" as a pattern delimiter.
          After reading in the pattern, pcretest goes on to read data lines as

    (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
          and 16-bit fields in a compiled pattern, to simulate a pattern that
          was compiled on a host of opposite endianness.

21. The pcre-exec() function can now cope with patterns that were compiled on
    hosts of opposite endianness, with this restriction:

      As for any compiled expression that is saved and used later, the tables
      pointer field cannot be preserved; the extra_data field in the arguments
      to pcre_exec() should be used to pass in a tables address if a value
      other than the default internal tables were used at compile time.

22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
    now diagnosed as an error. Previously, most of the time, a negative number
    would have been treated as zero, but if in addition "ovector" was passed as
    NULL, a crash could occur.

23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
    new versions from the libtool 1.5 distribution (the last one is a copy of
    a file called libtool.m4). This seems to have fixed the need to patch
    "configure" to support Darwin 1.3 (which I used to do). However, I still
    had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my

24. Changed the PCRE licence to be the more standard "BSD" licence.

Version 4.5 01-Dec-03

 1. There has been some re-arrangement of the code for the match() function so
    that it can be compiled in a version that does not call itself recursively.
    Instead, it keeps those local variables that need separate instances for
    each "recursion" in a frame on the heap, and gets/frees frames whenever it
    needs to "recurse". Keeping track of where control must go is done by means
    of setjmp/longjmp. The whole thing is implemented by a set of macros that
    hide most of the details from the main code, and operates only if
    NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
    "configure" mechanism, "--disable-stack-for-recursion" turns on this way of

    To make it easier for callers to provide specially tailored get/free
    functions for this usage, two new functions, pcre_stack_malloc, and
    pcre_stack_free, are used. They are always called in strict stacking order,
    and the size of block requested is always the same.

    The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
    PCRE has been compiled to use the stack or the heap for recursion. The
    -C option of pcretest uses this to show which version is compiled.

    A new data escape \S, is added to pcretest; it causes the amounts of store
    obtained and freed by both kinds of malloc/free at match time to be added
    to the output.

 2. Changed the locale test to use "fr_FR" instead of "fr" because that's
    what's available on my current Linux desktop machine.

 3. When matching a UTF-8 string, the test for a valid string at the start has
    been extended. If start_offset is not zero, PCRE now checks that it points
    to a byte that is the start of a UTF-8 character. If not, it returns
    PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
    this is necessary because there may be backward assertions in the pattern.
    When matching the same subject several times, it may save resources to use
    PCRE_NO_UTF8_CHECK on all but the first call if the string is long.

 4. The code for checking the validity of UTF-8 strings has been tightened so
    that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
    containing "overlong sequences".

 5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
    I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
    should have been "&", but it just so happened that all the cases this let
    through by mistake were picked up later in the function.

 6. I had used a variable called "isblank" - this is a C99 function, causing
    some compilers to warn. To avoid this, I renamed it (as "blankclass").

 7. Cosmetic: (a) only output another newline at the end of pcretest if it is
    prompting; (b) run "./pcretest /dev/null" at the start of the test script
    so the version is shown; (c) stop "make test" echoing "./RunTest".

 8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.

 9. The prototype for memmove() for systems that don't have it was using
    size_t, but the inclusion of the header that defines size_t was later. I've
    moved the #includes for the C headers earlier to avoid this.

10. Added some adjustments to the code to make it easier to compiler on certain
    special systems:

      (a) Some "const" qualifiers were missing.
      (b) Added the macro EXPORT before all exported functions; by default this
          is defined to be empty.
      (c) Changed the dftables auxiliary program (that builds chartables.c) so
          that it reads its output file name as an argument instead of writing
          to the standard output and assuming this can be redirected.

11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
    class containing characters with values greater than 255, PCRE compilation
    went into a loop.

12. A recursive reference to a subpattern that was within another subpattern
    that had a minimum quantifier of zero caused PCRE to crash. For example,
    (x(y(?2))z)? provoked this bug with a subject that got as far as the
    recursion. If the recursively-called subpattern itself had a zero repeat,
    that was OK.

13. In pcretest, the buffer for reading a data line was set at 30K, but the
    buffer into which it was copied (for escape processing) was still set at
    1024, so long lines caused crashes.

14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
    "internal error: code overflow...". This applied to any character class
    that was followed by a possessive quantifier.

15. Modified the Makefile to add libpcre.la as a prerequisite for
    libpcreposix.la because I was told this is needed for a parallel build to

16. If a pattern that contained .* following optional items at the start was
    studied, the wrong optimizing data was generated, leading to matching
    errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
    matching string must start with a or b or c. The correct conclusion for
    this pattern is that a match can start with any character.

Version 4.4 13-Aug-03

 1. In UTF-8 mode, a character class containing characters with values between
    127 and 255 was not handled correctly if the compiled pattern was studied.
    In fixing this, I have also improved the studying algorithm for such
    classes (slightly).

 2. Three internal functions had redundant arguments passed to them. Removal
    might give a very teeny performance improvement.

 3. Documentation bug: the value of the capture_top field in a callout is *one
    more than* the number of the hightest numbered captured substring.

 4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
    in incorrectly linking with a previously installed version. They now link
    explicitly with libpcre.la.

 5. configure.in no longer needs to recognize Cygwin specially.

 6. A problem in pcre.in for Windows platforms is fixed.

 7. If a pattern was successfully studied, and the -d (or /D) flag was given to
    pcretest, it used to include the size of the study block as part of its
    output. Unfortunately, the structure contains a field that has a different
    size on different hardware architectures. This meant that the tests that
    showed this size failed. As the block is currently always of a fixed size,
    this information isn't actually particularly useful in pcretest output, so
    I have just removed it.

 8. Three pre-processor statements accidentally did not start in column 1.
    Sadly, there are *still* compilers around that complain, even though
    standard C has not required this for well over a decade. Sigh.

 9. In pcretest, the code for checking callouts passed small integers in the
    callout_data field, which is a void * field. However, some picky compilers
    complained about the casts involved for this on 64-bit systems. Now
    pcretest passes the address of the small integer instead, which should get
    rid of the warnings.

10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
    both compile and run time, and gives an error if an invalid UTF-8 sequence
    is found. There is a option for disabling this check in cases where the
    string is known to be correct and/or the maximum performance is wanted.

11. In response to a bug report, I changed one line in Makefile.in from

        -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
        -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \

    to look similar to other lines, but I have no way of telling whether this
    is the right thing to do, as I do not use Windows. No doubt I'll get told
    if it's wrong...

Version 4.3 21-May-03

1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the

2. Some refactoring to improve the quality of the code:

   (i)   The utf8_table... variables are now declared "const".

   (ii)  The code for \cx, which used the "case flipping" table to upper case
         lower case letters, now just substracts 32. This is ASCII-specific,
         but the whole concept of \cx is ASCII-specific, so it seems

   (iii) PCRE was using its character types table to recognize decimal and
         hexadecimal digits in the pattern. This is silly, because it handles
         only 0-9, a-f, and A-F, but the character types table is locale-
         specific, which means strange things might happen. A private
         table is now used for this - though it costs 256 bytes, a table is
         much faster than multiple explicit tests. Of course, the standard
         character types table is still used for matching digits in subject
         strings against \d.

   (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
         ending in _t are). So I've renamed it as ESC_tee.

3. The first argument for regexec() in the POSIX wrapper should have been
   defined as "const".

4. Changed pcretest to use malloc() for its buffers so that they can be
   Electric Fenced for debugging.

5. There were several places in the code where, in UTF-8 mode, PCRE would try
   to read one or more bytes before the start of the subject string. Often this
   had no effect on PCRE's behaviour, but in some circumstances it could
   provoke a segmentation fault.

6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
   to try to read one or more bytes before the start of the subject string.

7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
   UTF-8 support could misbehave in various ways if the subject string
   contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
   area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
   back over UTF-8 characters.)

Version 4.2 14-Apr-03

1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.

2. Changes to the building process, supplied by Ronald Landheer-Cieslak
     [ON_WINDOWS]: new variable, "#" on non-Windows platforms
     [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
     [WIN_PREFIX]: new variable, "cyg" for Cygwin
     * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
       and BUILD_EXEEXT
     Note: automatic setting of the BUILD variables is not yet working
     set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
       compile-time but not at link-time
     [LINK]: use for linking executables only
     make different versions for Windows and non-Windows
     [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
     [LINK_FOR_BUILD]: new variable
     [OBJEXT]: use throughout
     [EXEEXT]: use throughout
     <winshared>: new target
     <wininstall>: new target
     <dftables.o>: use native compiler
     <dftables>: use native linker
     <install>: handle Windows platform correctly
     <clean>: ditto
     <check>: ditto
     copy DLL to top builddir before testing

   As part of these changes, -no-undefined was removed again. This was reported
   to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
   in any case.

3. Some tidies to get rid of compiler warnings:

   . In the match_data structure, match_limit was an unsigned long int, whereas
     match_call_count was an int. I've made them both unsigned long ints.

   . In pcretest the fact that a const uschar * doesn't automatically cast to
     a void * provoked a warning.

   . Turning on some more compiler warnings threw up some "shadow" variables
     and a few more missing casts.

4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
   option, a class that contained a single character with a value between 128
   and 255 (e.g. /[\xFF]/) caused PCRE to crash.

5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
   option, a class that contained several characters, but with at least one
   whose value was between 128 and 255 caused PCRE to crash.

Version 4.1 12-Mar-03

1. Compiling with gcc -pedantic found a couple of places where casts were
needed, and a string in dftables.c that was longer than standard compilers are
required to support.

2. Compiling with Sun's compiler found a few more places where the code could
be tidied up in order to avoid warnings.

3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
first of these names is deprecated in the latest Autoconf in favour of the name
CC_FOR_BUILD, because "host" is typically used to mean the system on which the
compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
analogy I have changed it to CFLAGS_FOR_BUILD.

4. Added -no-undefined to the linking command in the Makefile, because this is
apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
linking step for the pcreposix library.

5. PCRE was failing to diagnose the case of two named groups with the same

6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
literal character that is needed in the subject for a match, and scans along to
ensure that it is present before embarking on the full matching process. This
saves time in cases of nested unlimited repeats that are never going to match.
Problem: the scan can take a lot of time if the subject is very long (e.g.
megabytes), thus penalizing straightforward matches. It is now done only if the
amount of subject to be scanned is less than 1000 bytes.

7. A lesser problem with the same optimization is that it was recording the
first character of an anchored pattern as "needed", thus provoking a search
right along the subject, even when the first match of the pattern was going to
fail. The "needed" character is now not set for anchored patterns, unless it
follows something in the pattern that is of non-fixed length. Thus, it still
fulfils its original purpose of finding quick non-matches in cases of nested
unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.

Version 4.0 17-Feb-03

1. If a comment in an extended regex that started immediately after a meta-item
extended to the end of string, PCRE compiled incorrect data. This could lead to
all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.

2. Moved to autoconf 2.53 and libtool 1.4.2.

3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
the special perltest8 script is no longer needed - all the tests can be run
from a single perltest script.

4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
by \s. It has now been removed in PCRE. This means it isn't recognized as
whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
class [:space:] *does* include VT, thereby creating a mess.

5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
space and tab.

6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
its new features into the main test script, reducing the number of scripts.

7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
were backward compatible, and made the (?i) apply to the whole pattern, as if
/i were given. Now it behaves more logically, and applies the option setting
only to what follows. PCRE has been changed to follow suit. However, if it
finds options settings right at the start of the pattern, it extracts them into
the global options, as before. Thus, they show up in the info data.

8. Added support for the \Q...\E escape sequence. Characters in between are
treated as literals. This is slightly different from Perl in that $ and @ are
also handled as literals inside the quotes. In Perl, they will cause variable
interpolation. Note the following examples:

    Pattern            PCRE matches      Perl matches

    \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
    \Qabc\$xyz\E       abc\$xyz          abc\$xyz
    \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz

For compatibility with Perl, \Q...\E sequences are recognized inside character
classes as well as outside them.

9. Re-organized 3 code statements in pcretest to avoid "overflow in
floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
(size_t) cast to one statement in pcretest and one in pcreposix to avoid
signed/unsigned warnings.

10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
option for pcretest, so I've replaced it by a simple function that does just
that job.

11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
"pcregrep -".

12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
Java package. This provides some syntactic sugar for simple cases of what my
documentation calls "once-only subpatterns". A pattern such as x*+ is the same
as (?>x*). In other words, if what is inside (?>...) is just a single repeated
item, you can use this simplified notation. Note that only makes sense with
greedy quantifiers. Consequently, the use of the possessive quantifier forces
greediness, whatever the setting of the PCRE_UNGREEDY option.

13. A change of greediness default within a pattern was not taking effect at
the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
was abstracted outside.

14. PCRE now supports the \G assertion. It is true when the current matching
position is at the start point of the match. This differs from \A when the
starting offset is non-zero. Used with the /g option of pcretest (or similar
code), it works in the same way as it does for Perl's /g option. If all
alternatives of a regex begin with \G, the expression is anchored to the start
match position, and the "anchored" flag is set in the compiled expression.

15. Some bugs concerning the handling of certain option changes within patterns
have been fixed. These applied to options other than (?ims). For example,
"a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
been the other way round. Some of this was related to change 7 above.

16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
POSIX classes only within a class (e.g. /[[:alpha:]]/).

17. Added support for Perl's \C escape. This matches one byte, even in UTF8
mode. Unlike ".", it always matches newline, whatever the setting of
PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
assertions. Perl allows it, but it doesn't (in general) work because it can't
calculate the length of the lookbehind. At least, that's the case for Perl
5.8.0 - I've been told they are going to document that it doesn't work in

18. Added an error diagnosis for escapes that PCRE does not support: these are
\L, \l, \N, \P, \p, \U, \u, and \X.

19. Although correctly diagnosing a missing ']' in a character class, PCRE was
reading past the end of the pattern in cases such as /[abcd/.

20. PCRE was getting more memory than necessary for patterns with classes that
contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.

21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
compiling PCRE for use with Virtual Pascal.

22. Small fix to the Makefile to make it work properly if the build is done
outside the source tree.

23. Added a new extension: a condition to go with recursion. If a conditional
subpattern starts with (?(R) the "true" branch is used if recursion has
happened, whereas the "false" branch is used only at the top level.

24. When there was a very long string of literal characters (over 255 bytes
without UTF support, over 250 bytes with UTF support), the computation of how
much memory was required could be incorrect, leading to segfaults or other
strange effects.

25. PCRE was incorrectly assuming anchoring (either to start of subject or to
start of line for a non-DOTALL pattern) when a pattern started with (.*) and
there was a subsequent back reference to those brackets. This meant that, for
example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
possible to check for precisely this case. All we can do is abandon the
optimization if .* occurs inside capturing brackets when there are any back
references whatsoever. (See below for a better fix that came later.)

26. The handling of the optimization for finding the first character of a
non-anchored pattern, and for finding a character that is required later in the
match were failing in some cases. This didn't break the matching; it just
failed to optimize when it could. The way this is done has been re-implemented.

27. Fixed typo in error message for invalid (?R item (it said "(?p").

28. Added a new feature that provides some of the functionality that Perl
provides with (?{...}). The facility is termed a "callout". The way it is done
in PCRE is for the caller to provide an optional function, by setting
pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
global variable. By default it is unset, which disables all calling out. To get
the function called, the regex must include (?C) at appropriate points. This
is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
This provides a means of identifying different callout points. When PCRE
reaches such a point in the regex, if pcre_callout has been set, the external
function is called. It is provided with data in a structure called
pcre_callout_block, which is defined in pcre.h. If the function returns 0,
matching continues; if it returns a non-zero value, the match at the current
point fails. However, backtracking will occur if possible. [This was changed
later and other features added - see item 49 below.]

29. pcretest is upgraded to test the callout functionality. It provides a
callout function that displays information. By default, it shows the start of
the match and the current position in the text. There are some new data escapes
to vary what happens:

    \C+         in addition, show current contents of captured substrings
    \C-         do not supply a callout function
    \C!n        return 1 when callout number n is reached
    \C!n!m      return 1 when callout number n is reached for the mth time

30. If pcregrep was called with the -l option and just a single file name, it
output "<stdin>" if a match was found, instead of the file name.

31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
pcre_exec(). This saves a malloc/free per call. The default value of
POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
when configuring.

32. The default maximum size of a compiled pattern is 64K. There have been a
few cases of people hitting this limit. The code now uses macros to handle the
storing of links as offsets within the compiled pattern. It defaults to 2-byte
links, but this can be changed to 3 or 4 bytes by --with-link-size when
configuring. Tests 2 and 5 work only with 2-byte links because they output
debugging information about compiled patterns.

33. Internal code re-arrangements:

(a) Moved the debugging function for printing out a compiled regex into
    its own source file (printint.c) and used #include to pull it into
    pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
    separate copies.

(b) Defined the list of op-code names for debugging as a macro in
    internal.h so that it is next to the definition of the opcodes.

(c) Defined a table of op-code lengths for simpler skipping along compiled
    code. This is again a macro in internal.h so that it is next to the
    definition of the opcodes.

34. Added support for recursive calls to individual subpatterns, along the
lines of Robin Houston's patch (but implemented somewhat differently).

35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
allow it to read and process whole directories in Win32. This code was
contributed by Lionel Fourquaux; it has not been tested by me.

36. Added support for named subpatterns. The Python syntax (?P<name>...) is
used to name a group. Names consist of alphanumerics and underscores, and must
be unique. Back references use the syntax (?P=name) and recursive calls use
(?P>name) which is a PCRE extension to the Python extension. Groups still have
numbers. The function pcre_fullinfo() can be used after compilation to extract
a name/number map. There are three relevant calls:

  PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
  PCRE_INFO_NAMECOUNT            yields the number of entries
  PCRE_INFO_NAMETABLE            yields a pointer to the map.

The map is a vector of fixed-size entries. The size of each entry depends on
the length of the longest name used. The first two bytes of each entry are the
group number, most significant byte first. There follows the corresponding
name, zero terminated. The names are in alphabetical order.

37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
case instead of 255. Making it the same both with and without UTF-8 support
means that the same test output works with both.

38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
calling malloc() with a zero argument.

39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
optimization. I've improved things by keeping a bitmap of backreferences with
numbers 1-31 so that if .* occurs inside capturing brackets that are not in
fact referenced, the optimization can be applied. It is unlikely that a
relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
the match to follow \n) will appear inside brackets with a number greater than
31, but if it does, any back reference > 31 suppresses the optimization.

40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
of disabling numbered capturing parentheses. Any opening parenthesis that is
not followed by ? behaves as if it were followed by ?: but named parentheses
can still be used for capturing (and they will acquire numbers in the usual

41. Redesigned the return codes from the match() function into yes/no/error so
that errors can be passed back from deep inside the nested calls. A malloc
failure while inside a recursive subpattern call now causes the
PCRE_ERROR_NOMEMORY return instead of quietly going wrong.

42. It is now possible to set a limit on the number of times the match()
function is called in a call to pcre_exec(). This facility makes it possible to
limit the amount of recursion and backtracking, though not in a directly
obvious way, because the match() function is used in a number of different
circumstances. The count starts from zero for each position in the subject
string (for non-anchored patterns). The default limit is, for compatibility, a
large number, namely 10 000 000. You can change this in two ways:

(a) When configuring PCRE before making, you can use --with-match-limit=n
    to set a default value for the compiled library.

(b) For each call to pcre_exec(), you can pass a pcre_extra block in which
    a different value is set. See 45 below.

If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.

43. Added a new function pcre_config(int, void *) to enable run-time extraction
of things that can be changed at compile time. The first argument specifies
what is wanted and the second points to where the information is to be placed.
The current list of available information is:


The output is an integer that is set to one if UTF-8 support is available;
otherwise it is set to zero.


The output is an integer that it set to the value of the code that is used for
newline. It is either LF (10) or CR (13).


The output is an integer that contains the number of bytes used for internal
linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.


The output is an integer that contains the threshold above which the POSIX
interface uses malloc() for output vectors. See item 31 above.


The output is an unsigned integer that contains the default limit of the number
of match() calls in a pcre_exec() execution. See 42 above.

44. pcretest has been upgraded by the addition of the -C option. This causes it
to extract all the available output from the new pcre_config() function, and to
output it. The program then exits immediately.

45. A need has arisen to pass over additional data with calls to pcre_exec() in
order to support additional features. One way would have been to define
pcre_exec2() (for example) with extra arguments, but this would not have been
extensible, and would also have required all calls to the original function to
be mapped to the new one. Instead, I have chosen to extend the mechanism that
is used for passing in "extra" data from pcre_study().

The pcre_extra structure is now exposed and defined in pcre.h. It currently
contains the following fields:

  flags         a bitmap indicating which of the following fields are set
  study_data    opaque data from pcre_study()
  match_limit   a way of specifying a limit on match() calls for a specific
                  call to pcre_exec()
  callout_data  data for callouts (see 49 below)

The flag bits are also defined in pcre.h, and are


The pcre_study() function now returns one of these new pcre_extra blocks, with
the actual study data pointed to by the study_data field, and the
PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
before. That is, this change is entirely upwards-compatible and requires no
change to existing code.

If you want to pass in additional data to pcre_exec(), you can either place it
in a pcre_extra block provided by pcre_study(), or create your own pcre_extra

46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
data string contains the escape sequence \M, pcretest calls pcre_exec() several
times with different match limits, until it finds the minimum value needed for
pcre_exec() to complete. The value is then output. This can be instructive; for
most simple matches the number is quite small, but for pathological cases it
gets very large very quickly.

47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
returns the size of the data block pointed to by the study_data field in a
pcre_extra block, that is, the value that was passed as the argument to
pcre_malloc() when PCRE was getting memory in which to place the information
created by pcre_study(). The fourth argument should point to a size_t variable.
pcretest has been extended so that this information is shown after a successful
pcre_study() call when information about the compiled regex is being displayed.

48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
because what follows is always an absolute path. (Later: it turns out that this
is more than cosmetic for MinGW, because it doesn't like empty path

49. Some changes have been made to the callout feature (see 28 above):

(i)  A callout function now has three choices for what it returns:

       0  =>  success, carry on matching
     > 0  =>  failure at this point, but backtrack if possible
     < 0  =>  serious error, return this value from pcre_exec()

     Negative values should normally be chosen from the set of PCRE_ERROR_xxx
     values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
     "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
     use by callout functions. It will never be used by PCRE itself.

(ii) The pcre_extra structure (see 45 above) has a void * field called
     callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
     pcre_callout_block structure has a field of the same name. The contents of
     the field passed in the pcre_extra structure are passed to the callout
     function in the corresponding field in the callout block. This makes it
     easier to use the same callout-containing regex from multiple threads. For
     testing, the pcretest program has a new data escape

       \C*n        pass the number n (may be negative) as callout_data

     If the callout function in pcretest receives a non-zero value as
     callout_data, it returns that value.

50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
there were some redundant $(CFLAGS) in commands that are now specified as
$(LINK), which already includes $(CFLAGS).

51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
has been compiled with UTF-8 support *and* pcre_compile() has been compiled
with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
one-byte characters throughout. Note that case-insensitive matching applies
only to characters whose values are less than 256. PCRE doesn't support the
notion of cases for higher-valued characters.

(i)   A character class whose characters are all within 0-255 is handled as
      a bit map, and the map is inverted for negative classes. Previously, a
      character > 255 always failed to match such a class; however it should
      match if the class was a negative one (e.g. [^ab]). This has been fixed.

(ii)  A negated character class with a single character < 255 is coded as
      "not this character" (OP_NOT). This wasn't working properly when the test
      character was multibyte, either singly or repeated.

(iii) Repeats of multibyte characters are now handled correctly in UTF-8
      mode, for example: \x{100}{2,3}.

(iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
      singly or repeated) now correctly test multibyte characters. However,
      PCRE doesn't recognize any characters with values greater than 255 as
      digits, spaces, or word characters. Such characters always match \D, \S,
      and \W, and never match \d, \s, or \w.

(v)   Classes may now contain characters and character ranges with values
      greater than 255. For example: [ab\x{100}-\x{400}].

(vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
      PCRE in UTF-8 mode.

52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
retained for backwards compatibility. (Note that LASTLITERAL is also a byte

53. The single man page has become too large. I have therefore split it up into
a number of separate man pages. These also give rise to individual HTML pages;
these are now put in a separate directory, and there is an index.html page that
lists them all. Some hyperlinking between the pages has been installed.

54. Added convenience functions for handling named capturing parentheses.

55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
are faulted.

56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
calling configure. These values are used when compiling the dftables.c program
which is run to generate the source of the default character tables. They
default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
you will need to set these values.

57. Updated the building process for Windows DLL, as provided by Fred Cox.

Version 3.9 02-Jan-02

1. A bit of extraneous text had somehow crept into the pcregrep documentation.

2. If --disable-static was given, the building process failed when trying to
build pcretest and pcregrep. (For some reason it was using libtool to compile
them, which is not right, as they aren't part of the library.)

Version 3.8 18-Dec-01

1. The experimental UTF-8 code was completely screwed up. It was packing the
bytes in the wrong order. How dumb can you get?

Version 3.7 29-Oct-01

1. In updating pcretest to check change 1 of version 3.6, I screwed up.
This caused pcretest, when used on the test data, to segfault. Unfortunately,
this didn't happen under Solaris 8, where I normally test things.

2. The Makefile had to be changed to make it work on BSD systems, where 'make'
doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
this fix an hour or so after the initial 3.7 release.)

Version 3.6 23-Oct-01

1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
offsets passed as NULL with zero offset count.

2. The config.guess and config.sub files had not been updated when I moved to
the latest autoconf.

Version 3.5 15-Aug-01

1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
had been forgotten.

2. By using declared but undefined structures, we can avoid using "void"
definitions in pcre.h while keeping the internal definitions of the structures

3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
user point of view, this means that both static and shared libraries are built
by default, but this can be individually controlled. More of the work of
handling this static/shared cases is now inside libtool instead of PCRE's make

4. The pcretest utility is now installed along with pcregrep because it is
useful for users (to test regexs) and by doing this, it automatically gets
relinked by libtool. The documentation has been turned into a man page, so
there are now .1, .txt, and .html versions in /doc.

5. Upgrades to pcregrep:
   (i)   Added long-form option names like gnu grep.
   (ii)  Added --help to list all options with an explanatory phrase.
   (iii) Added -r, --recursive to recurse into sub-directories.
   (iv)  Added -f, --file to read patterns from a file.

6. pcre_exec() was referring to its "code" argument before testing that
argument for NULL (and giving an error if it was NULL).

7. Upgraded Makefile.in to allow for compiling in a different directory from
the source directory.

8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
options bits, the pointer it was passed was to an int instead of to an unsigned
long int. This mattered only on 64-bit systems.

9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
generated) instead of pcre.in, which it its source. Also made the same change
in several of the .c files.

10. A new release of gcc defines printf() as a macro, which broke pcretest
because it had an ifdef in the middle of a string argument for printf(). Fixed
by using separate calls to printf().

11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
script, to force use of CR or LF instead of \n in the source. On non-Unix
systems, the value can be set in config.h.

12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
absolute limit. Changed the text of the error message to make this clear, and
likewise updated the man page.

13. The limit of 99 on the number of capturing subpatterns has been removed.
The new limit is 65535, which I hope will not be a "real" limit.

Version 3.4 22-Aug-00

1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.

2. Diagnose condition (?(0) as an error instead of crashing on matching.

Version 3.3 01-Aug-00

1. If an octal character was given, but the value was greater than \377, it
was not getting masked to the least significant bits, as documented. This could
lead to crashes in some systems.

2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.

3. Added the functions pcre_free_substring() and pcre_free_substring_list().
These just pass their arguments on to (pcre_free)(), but they are provided
because some uses of PCRE bind it to non-C systems that can call its functions,
but cannot call free() or pcre_free() directly.

4. Add "make test" as a synonym for "make check". Corrected some comments in
the Makefile.

5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the

6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
command called pgrep for grepping around the active processes.

7. Added the beginnings of support for UTF-8 character strings.

8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
RANLIB to ./ltconfig so that they are used by libtool. I think these are all
the relevant ones. (AR is not passed because ./ltconfig does its own figuring
out for the ar command.)

Version 3.2 12-May-00

This is purely a bug fixing release.

1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
of ZA. This was just one example of several cases that could provoke this bug,
which was introduced by change 9 of version 2.00. The code for breaking
infinite loops after an iteration that matches an empty string was't working

2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
when matched against abbab (for example). After matching an empty string, it
wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
caused it to match further down the string than it should.

3. The code contained an inclusion of sys/types.h. It isn't clear why this
was there because it doesn't seem to be needed, and it causes trouble on some
systems, as it is not a Standard C header. It has been removed.

4. Made 4 silly changes to the source to avoid stupid compiler warnings that
were reported on the Macintosh. The changes were from

  while ((c = *(++ptr)) != 0 && c != '\n');
  while ((c = *(++ptr)) != 0 && c != '\n') ;

Totally extraordinary, but if that's what it takes...

5. PCRE is being used in one environment where neither memmove() nor bcopy() is
available. Added HAVE_BCOPY and an autoconf test for it; if neither
HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
assumes the way PCRE uses memmove() (always moving upwards).

6. PCRE is being used in one environment where strchr() is not available. There
was only one use in pcre.c, and writing it out to avoid strchr() probably gives
faster code anyway.

Version 3.1 09-Feb-00

The only change in this release is the fixing of some bugs in Makefile.in for
the "install" target:

(1) It was failing to install pcreposix.h.

(2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.

Version 3.0 01-Feb-00

1. Add support for the /+ modifier to perltest (to output $` like it does in

2. Add support for the /g modifier to perltest.

3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
matches null strings.

4. Fix perltest so that it doesn't do unwanted things when fed an empty
pattern. Perl treats empty patterns specially - it reuses the most recent
pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this

5. The POSIX interface was broken in that it was just handing over the POSIX
captured string vector to pcre_exec(), but (since release 2.00) PCRE has
required a bigger vector, with some working space on the end. This means that
the POSIX wrapper now has to get and free some memory, and copy the results.

6. Added some simple autoconf support, placing the test data and the
documentation in separate directories, re-organizing some of the
information files, and making it build pcre-config (a GNU standard). Also added
libtool support for building PCRE as a shared library, which is now the

7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
09 are not valid octal constants. Single digits will be used for minor values
less than 10.

8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
existing programs that set these in the POSIX interface can use PCRE without

9. Added a new function, pcre_fullinfo() with an extensible interface. It can
return all that pcre_info() returns, plus additional data. The pcre_info()
function is retained for compatibility, but is considered to be obsolete.

10. Added experimental recursion feature (?R) to handle one common case that
Perl 5.6 will be able to do with (?p{...}).

11. Added support for POSIX character classes like [:alpha:], which Perl is

Version 2.08 31-Aug-99

1. When startoffset was not zero and the pattern began with ".*", PCRE was not
trying to match at the startoffset position, but instead was moving forward to
the next newline as if a previous match had failed.

2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
and could get into a loop if a null string was matched other than at the start
of the subject.

3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
be distinguished at compile time, and for completeness also added PCRE_DATE.

5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
in GnuWin32 environments.

Version 2.07 29-Jul-99

1. The documentation is now supplied in plain text form and HTML as well as in
the form of man page sources.

2. C++ compilers don't like assigning (void *) values to other pointer types.
In particular this affects malloc(). Although there is no problem in Standard
C, I've put in casts to keep C++ compilers happy.

3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
should be (const char *).

4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
be useful for non-Unix systems who don't want to bother with the POSIX stuff.
However, I haven't made this a standard facility. The documentation doesn't
mention it, and the Makefile doesn't support it.

5. The Makefile now contains an "install" target, with editable destinations at
the top of the file. The pcretest program is not installed.

6. pgrep -V now gives the PCRE version number and date.

7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
causing the entire string to be ignored, instead of just the last character.

8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
non-matching string, it can take a very, very long time, even for strings of
quite modest length, because of the nested recursion. PCRE now does better in
some of these cases. It does this by remembering the last required literal
character in the pattern, and pre-searching the subject to ensure it is present
before running the real match. In other words, it applies a heuristic to detect
some types of certain failure quickly, and in the above example, if presented
with a string that has no trailing " it gives "no match" very quickly.

9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
other alternatives are tried instead.

Version 2.06 09-Jun-99

1. Change pcretest's output for amount of store used to show just the code
space, because the remainder (the data block) varies in size between 32-bit and
64-bit systems.

2. Added an extra argument to pcre_exec() to supply an offset in the subject to
start matching at. This allows lookbehinds to work when searching for multiple
occurrences in a string.

3. Added additional options to pcretest for testing multiple occurrences:

   /+   outputs the rest of the string that follows a match
   /g   loops for multiple occurrences, using the new startoffset argument
   /G   loops for multiple occurrences by passing an incremented pointer

4. PCRE wasn't doing the "first character" optimization for patterns starting
with \b or \B, though it was doing it for other lookbehind assertions. That is,
it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
the letter 'x'. On long subject strings, this gives a significant speed-up.

Version 2.05 21-Apr-99

1. Changed the type of magic_number from int to long int so that it works
properly on 16-bit systems.

2. Fixed a bug which caused patterns starting with .* not to work correctly
when the subject string contained newline characters. PCRE was assuming
anchoring for such patterns in all cases, which is not correct because .* will
not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
DOTALL is set at top level; otherwise it knows that patterns starting with .*
must be retried after every newline in the subject.

Version 2.04 18-Feb-99

1. For parenthesized subpatterns with repeats whose minimum was zero, the
computation of the store needed to hold the pattern was incorrect (too large).
If such patterns were nested a few deep, this could multiply and become a real

2. Added /M option to pcretest to show the memory requirement of a specific
pattern. Made -m a synonym of -s (which does this globally) for compatibility.

3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
compiled in such a way that the backtracking after subsequent failure was
pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.

Version 2.03 02-Feb-99

1. Fixed typo and small mistake in man page.

2. Added 4th condition (GPL supersedes if conflict) and created separate
LICENCE file containing the conditions.

3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
Perl, that is the internal \ allows the delimiter to be included in the
pattern. Locked out the use of \ as a delimiter. If \ immediately follows
the final delimiter, add \ to the end of the pattern (to test the error).

4. Added the convenience functions for extracting substrings after a successful
match. Updated pcretest to make it able to test these functions.

Version 2.02 14-Jan-99

1. Initialized the working variables associated with each extraction so that
their saving and restoring doesn't refer to uninitialized store.

2. Put dummy code into study.c in order to trick the optimizer of the IBM C
compiler for OS/2 into generating correct code. Apparently IBM isn't going to
fix the problem.

3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
calls, and wasn't printing the correct value for compiling calls. Increased the
default value of LOOPREPEAT, and the number of significant figures in the

4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.

5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
a building problem on Windows NT with a FAT file system.

Version 2.01 21-Oct-98

1. Changed the API for pcre_compile() to allow for the provision of a pointer
to character tables built by pcre_maketables() in the current locale. If NULL
is passed, the default tables are used.

Version 2.00 24-Sep-98

1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
it any more.

2. Allow quantification of (?>) groups, and make it work correctly.

3. The first character computation wasn't working for (?>) groups.

4. Correct the implementation of \Z (it is permitted to match on the \n at the
end of the subject) and add 5.005's \z, which really does match only at the
very end of the subject.

5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.

6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
localized options. All options to pcre_study() were also removed.

7. Add other new features from 5.005:

   $(?<=           positive lookbehind
   $(?<!           negative lookbehind
   (?imsx-imsx)    added the unsetting capability
                   such a setting is global if at outer level; local otherwise
   (?imsx-imsx:)   non-capturing groups with option setting
   (?(cond)re|re)  conditional pattern matching

   A backreference to itself in a repeated group matches the previous
   captured string.

8. General tidying up of studying (both automatic and via "study")
consequential on the addition of new assertions.

9. As in 5.005, unlimited repeated groups that could match an empty substring
are no longer faulted at compile time. Instead, the loop is forcibly broken at
runtime if any iteration does actually match an empty substring.

10. Include the RunTest script in the distribution.

11. Added tests from the Perl 5.005_02 distribution. This showed up a few
discrepancies, some of which were old and were also with respect to 5.004. They
have now been fixed.

Version 1.09 28-Apr-98

1. A negated single character class followed by a quantifier with a minimum
value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
program crashes, or just wrong answers. This did not apply to negated classes
containing more than one character, or to minima other than one.

Version 1.08 27-Mar-98

1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.

2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
latter must appear before anything that relies on it in the pattern.

Version 1.07 16-Feb-98

1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
repeat of a potentially empty string).

Version 1.06 23-Jan-98

1. Added Markus Oberhumer's little patches for C++.

2. Literal strings longer than 255 characters were broken.

Version 1.05 23-Dec-97

1. Negated character classes containing more than one character were failing if
PCRE_CASELESS was set at run time.

Version 1.04 19-Dec-97

1. Corrected the man page, where some "const" qualifiers had been omitted.

2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
input syntax.

3. Fixed memory leak which occurred when a regex with back references was
matched with an offsets vector that wasn't big enough. The temporary memory
that is used in this case wasn't being freed if the match failed.

4. Tidied pcretest to ensure it frees memory that it gets.

5. Temporary memory was being obtained in the case where the passed offsets
vector was exactly big enough.

6. Corrected definition of offsetof() from change 5 below.

7. I had screwed up change 6 below and broken the rules for the use of
setjmp(). Now fixed.

Version 1.03 18-Dec-97

1. A erroneous regex with a missing opening parenthesis was correctly
diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
on some systems.

2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
it was reported that one broken compiler failed on the former because "code" is
also an independent variable.

3. The erroneous regex a[]b caused an array overrun reference.

4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
fail on data ending with that character. (It was going on too far, and checking
the next character, typically a binary zero.) This was specific to the
optimized code for single-character negative classes.

5. Added a contributed patch from the TIN world which does the following:

  + Add an undef for memmove, in case the the system defines a macro for it.

  + Add a definition of offsetof(), in case there isn't one. (I don't know
    the reason behind this - offsetof() is part of the ANSI standard - but
    it does no harm).

  + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
    most of the places where whitespace preceded '#'. I have given up and
    allowed the remaining 2 cases to be at the margin.

  + Rename some variables in pcre to eliminate shadowing. This seems very
    pedantic, but does no harm, of course.

6. Moved the call to setjmp() into its own function, to get rid of warnings
from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.

7. Constructs such as \d{8,} were compiling into the equivalent of
\d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
outcome, but in this particular case used more store than had been allocated,
which caused the bug to be discovered because it threw up an internal error.

8. The debugging code in both pcre and pcretest for outputting the compiled
form of a regex was going wrong in the case of back references followed by
curly-bracketed repeats.

Version 1.02 12-Dec-97

1. Typos in pcre.3 and comments in the source fixed.

2. Applied a contributed patch to get rid of places where it used to remove
'const' from variables, and fixed some signed/unsigned and uninitialized
variable warnings.

3. Added the "runtest" target to Makefile.

4. Set default compiler flag to -O2 rather than just -O.

Version 1.01 19-Nov-97

1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
like /([ab]*)*/, that is, for classes with more than one character in them.

2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
as /((?>a*))*/ (a PCRE_EXTRA facility).

Version 1.00 18-Nov-97

1. Added compile-time macros to support systems such as SunOS4 which don't have
memmove() or strerror() but have other things that can be used instead.

2. Arranged that "make clean" removes the executables.

Version 0.99 27-Oct-97

1. Fixed bug in code for optimizing classes with only one character. It was
initializing a 32-byte map regardless, which could cause it to run off the end
of the memory it had got.

2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.

Version 0.98 22-Oct-97

1. Fixed bug in code for handling temporary memory usage when there are more
back references than supplied space in the ovector. This could cause segfaults.

Version 0.97 21-Oct-97

1. Added the \X "cut" facility, conditional on PCRE_EXTRA.

2. Optimized negated single characters not to use a bit map.

3. Brought error texts together as macro definitions; clarified some of them;
fixed one that was wrong - it said "range out of order" when it meant "invalid
escape sequence".

4. Changed some char * arguments to const char *.


6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in

Version 0.96 16-Oct-97

1. Added a simple "pgrep" utility to the distribution.

2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
where "ddd" means "one or more decimal digits".

3. Fixed serious bug. If a pattern had a back reference, but the call to
pcre_exec() didn't supply a large enough ovector to record the related
identifying subpattern, the match always failed. PCRE now remembers the number
of the largest back reference, and gets some temporary memory in which to save
the offsets during matching if necessary, in order to ensure that
backreferences always work.

4. Increased the compatibility with Perl in a number of ways:

  (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
      to request this handling. The option can be set at compile or exec time.

  (b) $ matches before a terminating newline by default; an option
      PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
      mode). The option can be set at compile or exec time.

  (c) The handling of \ followed by a digit other than 0 is now supposed to be
      the same as Perl's. If the decimal number it represents is less than 10
      or there aren't that many previous left capturing parentheses, an octal
      escape is read. Inside a character class, it's always an octal escape,
      even if it is a single digit.

  (d) An escaped but undefined alphabetic character is taken as a literal,
      unless PCRE_EXTRA is set. Currently this just reserves the remaining

  (e) {0} is now permitted. (The previous item is removed from the compiled

5. Changed all the names of code files so that the basic parts are no longer
than 10 characters, and abolished the teeny "globals.c" file.

6. Changed the handling of character classes; they are now done with a 32-byte
bit map always.

7. Added the -d and /D options to pcretest to make it possible to look at the
internals of compilation without having to recompile pcre.

Version 0.95 23-Sep-97

1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
\x20 at the start of a run of normal characters. These were being treated as
real characters, instead of the source characters being re-checked.

Version 0.94 18-Sep-97

1. The functions are now thread-safe, with the caveat that the global variables
containing pointers to malloc() and free() or alternative functions are the
same for all threads.

2. Get pcre_study() to generate a bitmap of initial characters for non-
anchored patterns when this is possible, and use it if passed to pcre_exec().

Version 0.93 15-Sep-97

1. /(b)|(:+)/ was computing an incorrect first character.

2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
but not actually doing anything yet.

3. Treat "-" characters in classes that cannot be part of ranges as literals,
as Perl does (e.g. [-az] or [az-]).

4. Set the anchored flag if a branch starts with .* or .*? because that tests
all possible positions.

5. Split up into different modules to avoid including unneeded functions in a
compiled binary. However, compile and exec are still in one module. The "study"
function is split off.

6. The character tables are now in a separate module whose source is generated
by an auxiliary program - but can then be edited by hand if required. There are
now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
toupper() in the code.

7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
make them global. Abolish the function for setting them, as the caller can now
set them directly.

Version 0.92 11-Sep-97

1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
(e.g. /a{1,3}/) was broken (I mis-optimized it).

2. Caseless matching was not working in character classes if the characters in
the pattern were in upper case.

3. Make ranges like [W-c] work in the same way as Perl for caseless matching.

4. Make PCRE_ANCHORED public and accept as a compile option.

5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
pass them.

6. Give an error if bad option bits passed at compile or run time.

7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
pcretest to cause it to pass that flag.

8. Add pcre_info(), to get the number of identifying subpatterns, the stored
options, and the first character, if set.

9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.

Version 0.91 10-Sep-97

1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
match the empty string as in /(a*)*/. It was looping and ultimately crashing.

2. PCRE was looping on encountering an indefinitely repeated back reference to
a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
Perl does - treats the match as successful.