Contents of /code/trunk/ChangeLog

ChangeLog for PCRE
------------------

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
       libraries
     [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
name.

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
future.

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
way).

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:

  PCRE_CONFIG_UTF8

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

  PCRE_CONFIG_NEWLINE

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).

  PCRE_CONFIG_LINK_SIZE

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.

  PCRE_CONFIG_POSIX_MALLOC_THRESHOLD

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

  PCRE_CONFIG_MATCH_LIMIT

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

  PCRE_EXTRA_STUDY_DATA
  PCRE_EXTRA_MATCH_LIMIT
  PCRE_EXTRA_CALLOUT_DATA

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
block.

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
components.)

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
value.)

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
private.

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
file.

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
Makefile.

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
correctly.

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');
to
  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
pcretest).

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
effect.

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
default.

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
modification.

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
adopting.


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
problem.

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
times.

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 *.

5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).

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


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
      escapes.

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

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.

****