Initial revision

Written by: Philip Hazel <ph10@cam.ac.uk>

University of Cambridge Computing Service,

Cambridge, England. Phone: +44 1223 334714.

Copyright (c) 1997-2000 University of Cambridge

PCRE LICENCE

------------

PCRE is a library of functions to support regular expressions whose syntax

and semantics are as close as possible to those of the Perl 5 language.

Written by: Philip Hazel <ph10@cam.ac.uk>

University of Cambridge Computing Service,

Cambridge, England. Phone: +44 1223 334714.

Copyright (c) 1997-2000 University of Cambridge

Permission is granted to anyone to use this software for any purpose on any

computer system, and to redistribute it freely, subject to the following

restrictions:

1. This software is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

2. The origin of this software must not be misrepresented, either by

   explicit claim or by omission.

3. Altered versions must be plainly marked as such, and must not be

   misrepresented as being the original software.

4. If PCRE is embedded in any software that is released under the GNU

   General Purpose Licence (GPL), then the terms of that licence shall

   supersede any condition above with which it is incompatible.

End

ChangeLog for PCRE

------------------

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.

****

PCRE LICENCE

------------

PCRE is a library of functions to support regular expressions whose syntax

and semantics are as close as possible to those of the Perl 5 language.

Written by: Philip Hazel <ph10@cam.ac.uk>

University of Cambridge Computing Service,

Cambridge, England. Phone: +44 1223 334714.

Copyright (c) 1997-2000 University of Cambridge

Permission is granted to anyone to use this software for any purpose on any

computer system, and to redistribute it freely, subject to the following

restrictions:

1. This software is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

2. The origin of this software must not be misrepresented, either by

   explicit claim or by omission.

3. Altered versions must be plainly marked as such, and must not be

   misrepresented as being the original software.

4. If PCRE is embedded in any software that is released under the GNU

   General Purpose Licence (GPL), then the terms of that licence shall

   supersede any condition above with which it is incompatible.

End