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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 4.3 21-May-03
5    ---------------------
7    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
8       Makefile.
10    2. Some refactoring to improve the quality of the code:
12       (i)   The utf8_table... variables are now declared "const".
14       (ii)  The code for \cx, which used the "case flipping" table to upper case
15             lower case letters, now just substracts 32. This is ASCII-specific,
16             but the whole concept of \cx is ASCII-specific, so it seems
17             reasonable.
19       (iii) PCRE was using its character types table to recognize decimal and
20             hexadecimal digits in the pattern. This is silly, because it handles
21             only 0-9, a-f, and A-F, but the character types table is locale-
22             specific, which means strange things might happen. A private
23             table is now used for this - though it costs 256 bytes, a table is
24             much faster than multiple explicit tests. Of course, the standard
25             character types table is still used for matching digits in subject
26             strings against \d.
28       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
29             ending in _t are). So I've renamed it as ESC_tee.
31    3. The first argument for regexec() in the POSIX wrapper should have been
32       defined as "const".
34    4. Changed pcretest to use malloc() for its buffers so that they can be
35       Electric Fenced for debugging.
37    5. There were several places in the code where, in UTF-8 mode, PCRE would try
38       to read one or more bytes before the start of the subject string. Often this
39       had no effect on PCRE's behaviour, but in some circumstances it could
40       provoke a segmentation fault.
42    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
43       to try to read one or more bytes before the start of the subject string.
45    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
46       UTF-8 support could misbehave in various ways if the subject string
47       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
48       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
49       back over UTF-8 characters.)
52    Version 4.2 14-Apr-03
53    ---------------------
55    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
57    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
58         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
59         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
60         [WIN_PREFIX]: new variable, "cyg" for Cygwin
61         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
62           and BUILD_EXEEXT
63         Note: automatic setting of the BUILD variables is not yet working
64         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
65           compile-time but not at link-time
66         [LINK]: use for linking executables only
67         make different versions for Windows and non-Windows
68         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
69           libraries
70         [LINK_FOR_BUILD]: new variable
71         [OBJEXT]: use throughout
72         [EXEEXT]: use throughout
73         <winshared>: new target
74         <wininstall>: new target
75         <dftables.o>: use native compiler
76         <dftables>: use native linker
77         <install>: handle Windows platform correctly
78         <clean>: ditto
79         <check>: ditto
80         copy DLL to top builddir before testing
82       As part of these changes, -no-undefined was removed again. This was reported
83       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
84       in any case.
86    3. Some tidies to get rid of compiler warnings:
88       . In the match_data structure, match_limit was an unsigned long int, whereas
89         match_call_count was an int. I've made them both unsigned long ints.
91       . In pcretest the fact that a const uschar * doesn't automatically cast to
92         a void * provoked a warning.
94       . Turning on some more compiler warnings threw up some "shadow" variables
95         and a few more missing casts.
97    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
98       option, a class that contained a single character with a value between 128
99       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
101    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
102       option, a class that contained several characters, but with at least one
103       whose value was between 128 and 255 caused PCRE to crash.
106    Version 4.1 12-Mar-03
107    ---------------------
109    1. Compiling with gcc -pedantic found a couple of places where casts were
110    needed, and a string in dftables.c that was longer than standard compilers are
111    required to support.
113    2. Compiling with Sun's compiler found a few more places where the code could
114    be tidied up in order to avoid warnings.
116    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
117    first of these names is deprecated in the latest Autoconf in favour of the name
118    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
119    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
120    analogy I have changed it to CFLAGS_FOR_BUILD.
122    4. Added -no-undefined to the linking command in the Makefile, because this is
123    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
124    linking step for the pcreposix library.
126    5. PCRE was failing to diagnose the case of two named groups with the same
127    name.
129    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
130    literal character that is needed in the subject for a match, and scans along to
131    ensure that it is present before embarking on the full matching process. This
132    saves time in cases of nested unlimited repeats that are never going to match.
133    Problem: the scan can take a lot of time if the subject is very long (e.g.
134    megabytes), thus penalizing straightforward matches. It is now done only if the
135    amount of subject to be scanned is less than 1000 bytes.
137    7. A lesser problem with the same optimization is that it was recording the
138    first character of an anchored pattern as "needed", thus provoking a search
139    right along the subject, even when the first match of the pattern was going to
140    fail. The "needed" character is now not set for anchored patterns, unless it
141    follows something in the pattern that is of non-fixed length. Thus, it still
142    fulfils its original purpose of finding quick non-matches in cases of nested
143    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
146    Version 4.0 17-Feb-03
147    ---------------------
149    1. If a comment in an extended regex that started immediately after a meta-item
150    extended to the end of string, PCRE compiled incorrect data. This could lead to
151    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
153    2. Moved to autoconf 2.53 and libtool 1.4.2.
155    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
156    the special perltest8 script is no longer needed - all the tests can be run
157    from a single perltest script.
159    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
160    by \s. It has now been removed in PCRE. This means it isn't recognized as
161    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
162    class [:space:] *does* include VT, thereby creating a mess.
164    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
165    space and tab.
167    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
168    its new features into the main test script, reducing the number of scripts.
170    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
171    were backward compatible, and made the (?i) apply to the whole pattern, as if
172    /i were given. Now it behaves more logically, and applies the option setting
173    only to what follows. PCRE has been changed to follow suit. However, if it
174    finds options settings right at the start of the pattern, it extracts them into
175    the global options, as before. Thus, they show up in the info data.
177    8. Added support for the \Q...\E escape sequence. Characters in between are
178    treated as literals. This is slightly different from Perl in that $ and @ are
179    also handled as literals inside the quotes. In Perl, they will cause variable
180    interpolation. Note the following examples:
182        Pattern            PCRE matches      Perl matches
184        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
185        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
186        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
188    For compatibility with Perl, \Q...\E sequences are recognized inside character
189    classes as well as outside them.
191    9. Re-organized 3 code statements in pcretest to avoid "overflow in
192    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
193    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
194    signed/unsigned warnings.
196    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
197    option for pcretest, so I've replaced it by a simple function that does just
198    that job.
200    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
201    "pcregrep -".
203    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
204    Java package. This provides some syntactic sugar for simple cases of what my
205    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
206    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
207    item, you can use this simplified notation. Note that only makes sense with
208    greedy quantifiers. Consequently, the use of the possessive quantifier forces
209    greediness, whatever the setting of the PCRE_UNGREEDY option.
211    13. A change of greediness default within a pattern was not taking effect at
212    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
213    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
214    was abstracted outside.
216    14. PCRE now supports the \G assertion. It is true when the current matching
217    position is at the start point of the match. This differs from \A when the
218    starting offset is non-zero. Used with the /g option of pcretest (or similar
219    code), it works in the same way as it does for Perl's /g option. If all
220    alternatives of a regex begin with \G, the expression is anchored to the start
221    match position, and the "anchored" flag is set in the compiled expression.
223    15. Some bugs concerning the handling of certain option changes within patterns
224    have been fixed. These applied to options other than (?ims). For example,
225    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
226    been the other way round. Some of this was related to change 7 above.
228    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
229    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
230    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
231    POSIX classes only within a class (e.g. /[[:alpha:]]/).
233    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
234    mode. Unlike ".", it always matches newline, whatever the setting of
235    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
236    assertions. Perl allows it, but it doesn't (in general) work because it can't
237    calculate the length of the lookbehind. At least, that's the case for Perl
238    5.8.0 - I've been told they are going to document that it doesn't work in
239    future.
241    18. Added an error diagnosis for escapes that PCRE does not support: these are
242    \L, \l, \N, \P, \p, \U, \u, and \X.
244    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
245    reading past the end of the pattern in cases such as /[abcd/.
247    20. PCRE was getting more memory than necessary for patterns with classes that
248    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
250    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
251    compiling PCRE for use with Virtual Pascal.
253    22. Small fix to the Makefile to make it work properly if the build is done
254    outside the source tree.
256    23. Added a new extension: a condition to go with recursion. If a conditional
257    subpattern starts with (?(R) the "true" branch is used if recursion has
258    happened, whereas the "false" branch is used only at the top level.
260    24. When there was a very long string of literal characters (over 255 bytes
261    without UTF support, over 250 bytes with UTF support), the computation of how
262    much memory was required could be incorrect, leading to segfaults or other
263    strange effects.
265    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
266    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
267    there was a subsequent back reference to those brackets. This meant that, for
268    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
269    possible to check for precisely this case. All we can do is abandon the
270    optimization if .* occurs inside capturing brackets when there are any back
271    references whatsoever. (See below for a better fix that came later.)
273    26. The handling of the optimization for finding the first character of a
274    non-anchored pattern, and for finding a character that is required later in the
275    match were failing in some cases. This didn't break the matching; it just
276    failed to optimize when it could. The way this is done has been re-implemented.
278    27. Fixed typo in error message for invalid (?R item (it said "(?p").
280    28. Added a new feature that provides some of the functionality that Perl
281    provides with (?{...}). The facility is termed a "callout". The way it is done
282    in PCRE is for the caller to provide an optional function, by setting
283    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
284    global variable. By default it is unset, which disables all calling out. To get
285    the function called, the regex must include (?C) at appropriate points. This
286    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
287    This provides a means of identifying different callout points. When PCRE
288    reaches such a point in the regex, if pcre_callout has been set, the external
289    function is called. It is provided with data in a structure called
290    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
291    matching continues; if it returns a non-zero value, the match at the current
292    point fails. However, backtracking will occur if possible. [This was changed
293    later and other features added - see item 49 below.]
295    29. pcretest is upgraded to test the callout functionality. It provides a
296    callout function that displays information. By default, it shows the start of
297    the match and the current position in the text. There are some new data escapes
298    to vary what happens:
300        \C+         in addition, show current contents of captured substrings
301        \C-         do not supply a callout function
302        \C!n        return 1 when callout number n is reached
303        \C!n!m      return 1 when callout number n is reached for the mth time
305    30. If pcregrep was called with the -l option and just a single file name, it
306    output "<stdin>" if a match was found, instead of the file name.
308    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
309    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
310    pcre_exec(). This saves a malloc/free per call. The default value of
311    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
312    when configuring.
314    32. The default maximum size of a compiled pattern is 64K. There have been a
315    few cases of people hitting this limit. The code now uses macros to handle the
316    storing of links as offsets within the compiled pattern. It defaults to 2-byte
317    links, but this can be changed to 3 or 4 bytes by --with-link-size when
318    configuring. Tests 2 and 5 work only with 2-byte links because they output
319    debugging information about compiled patterns.
321    33. Internal code re-arrangements:
323    (a) Moved the debugging function for printing out a compiled regex into
324        its own source file (printint.c) and used #include to pull it into
325        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
326        separate copies.
328    (b) Defined the list of op-code names for debugging as a macro in
329        internal.h so that it is next to the definition of the opcodes.
331    (c) Defined a table of op-code lengths for simpler skipping along compiled
332        code. This is again a macro in internal.h so that it is next to the
333        definition of the opcodes.
335    34. Added support for recursive calls to individual subpatterns, along the
336    lines of Robin Houston's patch (but implemented somewhat differently).
338    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
339    allow it to read and process whole directories in Win32. This code was
340    contributed by Lionel Fourquaux; it has not been tested by me.
342    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
343    used to name a group. Names consist of alphanumerics and underscores, and must
344    be unique. Back references use the syntax (?P=name) and recursive calls use
345    (?P>name) which is a PCRE extension to the Python extension. Groups still have
346    numbers. The function pcre_fullinfo() can be used after compilation to extract
347    a name/number map. There are three relevant calls:
349      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
350      PCRE_INFO_NAMECOUNT            yields the number of entries
351      PCRE_INFO_NAMETABLE            yields a pointer to the map.
353    The map is a vector of fixed-size entries. The size of each entry depends on
354    the length of the longest name used. The first two bytes of each entry are the
355    group number, most significant byte first. There follows the corresponding
356    name, zero terminated. The names are in alphabetical order.
358    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
359    case instead of 255. Making it the same both with and without UTF-8 support
360    means that the same test output works with both.
362    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
363    calling malloc() with a zero argument.
365    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
366    optimization. I've improved things by keeping a bitmap of backreferences with
367    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
368    fact referenced, the optimization can be applied. It is unlikely that a
369    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
370    the match to follow \n) will appear inside brackets with a number greater than
371    31, but if it does, any back reference > 31 suppresses the optimization.
373    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
374    of disabling numbered capturing parentheses. Any opening parenthesis that is
375    not followed by ? behaves as if it were followed by ?: but named parentheses
376    can still be used for capturing (and they will acquire numbers in the usual
377    way).
379    41. Redesigned the return codes from the match() function into yes/no/error so
380    that errors can be passed back from deep inside the nested calls. A malloc
381    failure while inside a recursive subpattern call now causes the
382    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
384    42. It is now possible to set a limit on the number of times the match()
385    function is called in a call to pcre_exec(). This facility makes it possible to
386    limit the amount of recursion and backtracking, though not in a directly
387    obvious way, because the match() function is used in a number of different
388    circumstances. The count starts from zero for each position in the subject
389    string (for non-anchored patterns). The default limit is, for compatibility, a
390    large number, namely 10 000 000. You can change this in two ways:
392    (a) When configuring PCRE before making, you can use --with-match-limit=n
393        to set a default value for the compiled library.
395    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
396        a different value is set. See 45 below.
398    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
400    43. Added a new function pcre_config(int, void *) to enable run-time extraction
401    of things that can be changed at compile time. The first argument specifies
402    what is wanted and the second points to where the information is to be placed.
403    The current list of available information is:
407    The output is an integer that is set to one if UTF-8 support is available;
408    otherwise it is set to zero.
412    The output is an integer that it set to the value of the code that is used for
413    newline. It is either LF (10) or CR (13).
417    The output is an integer that contains the number of bytes used for internal
418    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
422    The output is an integer that contains the threshold above which the POSIX
423    interface uses malloc() for output vectors. See item 31 above.
427    The output is an unsigned integer that contains the default limit of the number
428    of match() calls in a pcre_exec() execution. See 42 above.
430    44. pcretest has been upgraded by the addition of the -C option. This causes it
431    to extract all the available output from the new pcre_config() function, and to
432    output it. The program then exits immediately.
434    45. A need has arisen to pass over additional data with calls to pcre_exec() in
435    order to support additional features. One way would have been to define
436    pcre_exec2() (for example) with extra arguments, but this would not have been
437    extensible, and would also have required all calls to the original function to
438    be mapped to the new one. Instead, I have chosen to extend the mechanism that
439    is used for passing in "extra" data from pcre_study().
441    The pcre_extra structure is now exposed and defined in pcre.h. It currently
442    contains the following fields:
444      flags         a bitmap indicating which of the following fields are set
445      study_data    opaque data from pcre_study()
446      match_limit   a way of specifying a limit on match() calls for a specific
447                      call to pcre_exec()
448      callout_data  data for callouts (see 49 below)
450    The flag bits are also defined in pcre.h, and are
456    The pcre_study() function now returns one of these new pcre_extra blocks, with
457    the actual study data pointed to by the study_data field, and the
458    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
459    before. That is, this change is entirely upwards-compatible and requires no
460    change to existing code.
462    If you want to pass in additional data to pcre_exec(), you can either place it
463    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
464    block.
466    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
467    data string contains the escape sequence \M, pcretest calls pcre_exec() several
468    times with different match limits, until it finds the minimum value needed for
469    pcre_exec() to complete. The value is then output. This can be instructive; for
470    most simple matches the number is quite small, but for pathological cases it
471    gets very large very quickly.
473    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
474    returns the size of the data block pointed to by the study_data field in a
475    pcre_extra block, that is, the value that was passed as the argument to
476    pcre_malloc() when PCRE was getting memory in which to place the information
477    created by pcre_study(). The fourth argument should point to a size_t variable.
478    pcretest has been extended so that this information is shown after a successful
479    pcre_study() call when information about the compiled regex is being displayed.
481    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
482    because what follows is always an absolute path. (Later: it turns out that this
483    is more than cosmetic for MinGW, because it doesn't like empty path
484    components.)
486    49. Some changes have been made to the callout feature (see 28 above):
488    (i)  A callout function now has three choices for what it returns:
490           0  =>  success, carry on matching
491         > 0  =>  failure at this point, but backtrack if possible
492         < 0  =>  serious error, return this value from pcre_exec()
494         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
495         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
496         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
497         use by callout functions. It will never be used by PCRE itself.
499    (ii) The pcre_extra structure (see 45 above) has a void * field called
500         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
501         pcre_callout_block structure has a field of the same name. The contents of
502         the field passed in the pcre_extra structure are passed to the callout
503         function in the corresponding field in the callout block. This makes it
504         easier to use the same callout-containing regex from multiple threads. For
505         testing, the pcretest program has a new data escape
507           \C*n        pass the number n (may be negative) as callout_data
509         If the callout function in pcretest receives a non-zero value as
510         callout_data, it returns that value.
512    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
513    there were some redundant $(CFLAGS) in commands that are now specified as
514    $(LINK), which already includes $(CFLAGS).
516    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
517    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
518    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
519    one-byte characters throughout. Note that case-insensitive matching applies
520    only to characters whose values are less than 256. PCRE doesn't support the
521    notion of cases for higher-valued characters.
523    (i)   A character class whose characters are all within 0-255 is handled as
524          a bit map, and the map is inverted for negative classes. Previously, a
525          character > 255 always failed to match such a class; however it should
526          match if the class was a negative one (e.g. [^ab]). This has been fixed.
528    (ii)  A negated character class with a single character < 255 is coded as
529          "not this character" (OP_NOT). This wasn't working properly when the test
530          character was multibyte, either singly or repeated.
532    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
533          mode, for example: \x{100}{2,3}.
535    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
536          singly or repeated) now correctly test multibyte characters. However,
537          PCRE doesn't recognize any characters with values greater than 255 as
538          digits, spaces, or word characters. Such characters always match \D, \S,
539          and \W, and never match \d, \s, or \w.
541    (v)   Classes may now contain characters and character ranges with values
542          greater than 255. For example: [ab\x{100}-\x{400}].
544    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
545          PCRE in UTF-8 mode.
547    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
548    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
549    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
550    value.)
552    53. The single man page has become too large. I have therefore split it up into
553    a number of separate man pages. These also give rise to individual HTML pages;
554    these are now put in a separate directory, and there is an index.html page that
555    lists them all. Some hyperlinking between the pages has been installed.
557    54. Added convenience functions for handling named capturing parentheses.
559    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
560    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
561    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
562    are faulted.
564    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
565    calling configure. These values are used when compiling the dftables.c program
566    which is run to generate the source of the default character tables. They
567    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
568    you will need to set these values.
570    57. Updated the building process for Windows DLL, as provided by Fred Cox.
573    Version 3.9 02-Jan-02
574    ---------------------
576    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
578    2. If --disable-static was given, the building process failed when trying to
579    build pcretest and pcregrep. (For some reason it was using libtool to compile
580    them, which is not right, as they aren't part of the library.)
583    Version 3.8 18-Dec-01
584    ---------------------
586    1. The experimental UTF-8 code was completely screwed up. It was packing the
587    bytes in the wrong order. How dumb can you get?
590    Version 3.7 29-Oct-01
591    ---------------------
593    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
594    This caused pcretest, when used on the test data, to segfault. Unfortunately,
595    this didn't happen under Solaris 8, where I normally test things.
597    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
598    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
599    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
600    this fix an hour or so after the initial 3.7 release.)
603    Version 3.6 23-Oct-01
604    ---------------------
606    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
607    offsets passed as NULL with zero offset count.
609    2. The config.guess and config.sub files had not been updated when I moved to
610    the latest autoconf.
613    Version 3.5 15-Aug-01
614    ---------------------
616    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
617    had been forgotten.
619    2. By using declared but undefined structures, we can avoid using "void"
620    definitions in pcre.h while keeping the internal definitions of the structures
621    private.
623    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
624    user point of view, this means that both static and shared libraries are built
625    by default, but this can be individually controlled. More of the work of
626    handling this static/shared cases is now inside libtool instead of PCRE's make
627    file.
629    4. The pcretest utility is now installed along with pcregrep because it is
630    useful for users (to test regexs) and by doing this, it automatically gets
631    relinked by libtool. The documentation has been turned into a man page, so
632    there are now .1, .txt, and .html versions in /doc.
634    5. Upgrades to pcregrep:
635       (i)   Added long-form option names like gnu grep.
636       (ii)  Added --help to list all options with an explanatory phrase.
637       (iii) Added -r, --recursive to recurse into sub-directories.
638       (iv)  Added -f, --file to read patterns from a file.
640    6. pcre_exec() was referring to its "code" argument before testing that
641    argument for NULL (and giving an error if it was NULL).
643    7. Upgraded Makefile.in to allow for compiling in a different directory from
644    the source directory.
646    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
647    options bits, the pointer it was passed was to an int instead of to an unsigned
648    long int. This mattered only on 64-bit systems.
650    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
651    generated) instead of pcre.in, which it its source. Also made the same change
652    in several of the .c files.
654    10. A new release of gcc defines printf() as a macro, which broke pcretest
655    because it had an ifdef in the middle of a string argument for printf(). Fixed
656    by using separate calls to printf().
658    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
659    script, to force use of CR or LF instead of \n in the source. On non-Unix
660    systems, the value can be set in config.h.
662    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
663    absolute limit. Changed the text of the error message to make this clear, and
664    likewise updated the man page.
666    13. The limit of 99 on the number of capturing subpatterns has been removed.
667    The new limit is 65535, which I hope will not be a "real" limit.
670    Version 3.4 22-Aug-00
671    ---------------------
673    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
675    2. Diagnose condition (?(0) as an error instead of crashing on matching.
678    Version 3.3 01-Aug-00
679    ---------------------
681    1. If an octal character was given, but the value was greater than \377, it
682    was not getting masked to the least significant bits, as documented. This could
683    lead to crashes in some systems.
685    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
686    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
688    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
689    These just pass their arguments on to (pcre_free)(), but they are provided
690    because some uses of PCRE bind it to non-C systems that can call its functions,
691    but cannot call free() or pcre_free() directly.
693    4. Add "make test" as a synonym for "make check". Corrected some comments in
694    the Makefile.
696    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
697    Makefile.
699    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
700    command called pgrep for grepping around the active processes.
702    7. Added the beginnings of support for UTF-8 character strings.
704    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
705    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
706    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
707    out for the ar command.)
710    Version 3.2 12-May-00
711    ---------------------
713    This is purely a bug fixing release.
715    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
716    of ZA. This was just one example of several cases that could provoke this bug,
717    which was introduced by change 9 of version 2.00. The code for breaking
718    infinite loops after an iteration that matches an empty string was't working
719    correctly.
721    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
722    when matched against abbab (for example). After matching an empty string, it
723    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
724    caused it to match further down the string than it should.
726    3. The code contained an inclusion of sys/types.h. It isn't clear why this
727    was there because it doesn't seem to be needed, and it causes trouble on some
728    systems, as it is not a Standard C header. It has been removed.
730    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
731    were reported on the Macintosh. The changes were from
733      while ((c = *(++ptr)) != 0 && c != '\n');
734    to
735      while ((c = *(++ptr)) != 0 && c != '\n') ;
737    Totally extraordinary, but if that's what it takes...
739    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
740    available. Added HAVE_BCOPY and an autoconf test for it; if neither
741    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
742    assumes the way PCRE uses memmove() (always moving upwards).
744    6. PCRE is being used in one environment where strchr() is not available. There
745    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
746    faster code anyway.
749    Version 3.1 09-Feb-00
750    ---------------------
752    The only change in this release is the fixing of some bugs in Makefile.in for
753    the "install" target:
755    (1) It was failing to install pcreposix.h.
757    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
760    Version 3.0 01-Feb-00
761    ---------------------
763    1. Add support for the /+ modifier to perltest (to output $` like it does in
764    pcretest).
766    2. Add support for the /g modifier to perltest.
768    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
769    matches null strings.
771    4. Fix perltest so that it doesn't do unwanted things when fed an empty
772    pattern. Perl treats empty patterns specially - it reuses the most recent
773    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
774    effect.
776    5. The POSIX interface was broken in that it was just handing over the POSIX
777    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
778    required a bigger vector, with some working space on the end. This means that
779    the POSIX wrapper now has to get and free some memory, and copy the results.
781    6. Added some simple autoconf support, placing the test data and the
782    documentation in separate directories, re-organizing some of the
783    information files, and making it build pcre-config (a GNU standard). Also added
784    libtool support for building PCRE as a shared library, which is now the
785    default.
787    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
788    09 are not valid octal constants. Single digits will be used for minor values
789    less than 10.
791    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
792    existing programs that set these in the POSIX interface can use PCRE without
793    modification.
795    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
796    return all that pcre_info() returns, plus additional data. The pcre_info()
797    function is retained for compatibility, but is considered to be obsolete.
799    10. Added experimental recursion feature (?R) to handle one common case that
800    Perl 5.6 will be able to do with (?p{...}).
802    11. Added support for POSIX character classes like [:alpha:], which Perl is
803    adopting.
806    Version 2.08 31-Aug-99
807    ----------------------
809    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
810    trying to match at the startoffset position, but instead was moving forward to
811    the next newline as if a previous match had failed.
813    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
814    and could get into a loop if a null string was matched other than at the start
815    of the subject.
817    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
818    be distinguished at compile time, and for completeness also added PCRE_DATE.
820    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
821    in GnuWin32 environments.
824    Version 2.07 29-Jul-99
825    ----------------------
827    1. The documentation is now supplied in plain text form and HTML as well as in
828    the form of man page sources.
830    2. C++ compilers don't like assigning (void *) values to other pointer types.
831    In particular this affects malloc(). Although there is no problem in Standard
832    C, I've put in casts to keep C++ compilers happy.
834    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
835    should be (const char *).
837    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
838    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
839    However, I haven't made this a standard facility. The documentation doesn't
840    mention it, and the Makefile doesn't support it.
842    5. The Makefile now contains an "install" target, with editable destinations at
843    the top of the file. The pcretest program is not installed.
845    6. pgrep -V now gives the PCRE version number and date.
847    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
848    causing the entire string to be ignored, instead of just the last character.
850    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
851    non-matching string, it can take a very, very long time, even for strings of
852    quite modest length, because of the nested recursion. PCRE now does better in
853    some of these cases. It does this by remembering the last required literal
854    character in the pattern, and pre-searching the subject to ensure it is present
855    before running the real match. In other words, it applies a heuristic to detect
856    some types of certain failure quickly, and in the above example, if presented
857    with a string that has no trailing " it gives "no match" very quickly.
859    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
860    other alternatives are tried instead.
863    Version 2.06 09-Jun-99
864    ----------------------
866    1. Change pcretest's output for amount of store used to show just the code
867    space, because the remainder (the data block) varies in size between 32-bit and
868    64-bit systems.
870    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
871    start matching at. This allows lookbehinds to work when searching for multiple
872    occurrences in a string.
874    3. Added additional options to pcretest for testing multiple occurrences:
876       /+   outputs the rest of the string that follows a match
877       /g   loops for multiple occurrences, using the new startoffset argument
878       /G   loops for multiple occurrences by passing an incremented pointer
880    4. PCRE wasn't doing the "first character" optimization for patterns starting
881    with \b or \B, though it was doing it for other lookbehind assertions. That is,
882    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
883    the letter 'x'. On long subject strings, this gives a significant speed-up.
886    Version 2.05 21-Apr-99
887    ----------------------
889    1. Changed the type of magic_number from int to long int so that it works
890    properly on 16-bit systems.
892    2. Fixed a bug which caused patterns starting with .* not to work correctly
893    when the subject string contained newline characters. PCRE was assuming
894    anchoring for such patterns in all cases, which is not correct because .* will
895    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
896    DOTALL is set at top level; otherwise it knows that patterns starting with .*
897    must be retried after every newline in the subject.
900    Version 2.04 18-Feb-99
901    ----------------------
903    1. For parenthesized subpatterns with repeats whose minimum was zero, the
904    computation of the store needed to hold the pattern was incorrect (too large).
905    If such patterns were nested a few deep, this could multiply and become a real
906    problem.
908    2. Added /M option to pcretest to show the memory requirement of a specific
909    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
911    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
912    compiled in such a way that the backtracking after subsequent failure was
913    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
914    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
917    Version 2.03 02-Feb-99
918    ----------------------
920    1. Fixed typo and small mistake in man page.
922    2. Added 4th condition (GPL supersedes if conflict) and created separate
923    LICENCE file containing the conditions.
925    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
926    Perl, that is the internal \ allows the delimiter to be included in the
927    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
928    the final delimiter, add \ to the end of the pattern (to test the error).
930    4. Added the convenience functions for extracting substrings after a successful
931    match. Updated pcretest to make it able to test these functions.
934    Version 2.02 14-Jan-99
935    ----------------------
937    1. Initialized the working variables associated with each extraction so that
938    their saving and restoring doesn't refer to uninitialized store.
940    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
941    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
942    fix the problem.
944    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
945    calls, and wasn't printing the correct value for compiling calls. Increased the
946    default value of LOOPREPEAT, and the number of significant figures in the
947    times.
949    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
951    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
952    a building problem on Windows NT with a FAT file system.
955    Version 2.01 21-Oct-98
956    ----------------------
958    1. Changed the API for pcre_compile() to allow for the provision of a pointer
959    to character tables built by pcre_maketables() in the current locale. If NULL
960    is passed, the default tables are used.
963    Version 2.00 24-Sep-98
964    ----------------------
966    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
967    it any more.
969    2. Allow quantification of (?>) groups, and make it work correctly.
971    3. The first character computation wasn't working for (?>) groups.
973    4. Correct the implementation of \Z (it is permitted to match on the \n at the
974    end of the subject) and add 5.005's \z, which really does match only at the
975    very end of the subject.
977    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
979    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
980    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
981    localized options. All options to pcre_study() were also removed.
983    7. Add other new features from 5.005:
985       $(?<=           positive lookbehind
986       $(?<!           negative lookbehind
987       (?imsx-imsx)    added the unsetting capability
988                       such a setting is global if at outer level; local otherwise
989       (?imsx-imsx:)   non-capturing groups with option setting
990       (?(cond)re|re)  conditional pattern matching
992       A backreference to itself in a repeated group matches the previous
993       captured string.
995    8. General tidying up of studying (both automatic and via "study")
996    consequential on the addition of new assertions.
998    9. As in 5.005, unlimited repeated groups that could match an empty substring
999    are no longer faulted at compile time. Instead, the loop is forcibly broken at
1000    runtime if any iteration does actually match an empty substring.
1002    10. Include the RunTest script in the distribution.
1004    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
1005    discrepancies, some of which were old and were also with respect to 5.004. They
1006    have now been fixed.
1009    Version 1.09 28-Apr-98
1010    ----------------------
1012    1. A negated single character class followed by a quantifier with a minimum
1013    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
1014    program crashes, or just wrong answers. This did not apply to negated classes
1015    containing more than one character, or to minima other than one.
1018    Version 1.08 27-Mar-98
1019    ----------------------
1021    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
1023    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
1024    latter must appear before anything that relies on it in the pattern.
1027  Version 1.07 16-Feb-98  Version 1.07 16-Feb-98
1028  ----------------------  ----------------------

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