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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 4.2 14-Apr-03
5    ---------------------
6    
7  Version 1.09 28 Apr-98  1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
8    
9    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
10         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
11         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
12         [WIN_PREFIX]: new variable, "cyg" for Cygwin
13         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
14           and BUILD_EXEEXT
15         Note: automatic setting of the BUILD variables is not yet working
16         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
17           compile-time but not at link-time
18         [LINK]: use for linking executables only
19         make different versions for Windows and non-Windows
20         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
21           libraries
22         [LINK_FOR_BUILD]: new variable
23         [OBJEXT]: use throughout
24         [EXEEXT]: use throughout
25         <winshared>: new target
26         <wininstall>: new target
27         <dftables.o>: use native compiler
28         <dftables>: use native linker
29         <install>: handle Windows platform correctly
30         <clean>: ditto
31         <check>: ditto
32         copy DLL to top builddir before testing
33    
34       As part of these changes, -no-undefined was removed again. This was reported
35       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
36       in any case.
37    
38    3. Some tidies to get rid of compiler warnings:
39    
40       . In the match_data structure, match_limit was an unsigned long int, whereas
41         match_call_count was an int. I've made them both unsigned long ints.
42    
43       . In pcretest the fact that a const uschar * doesn't automatically cast to
44         a void * provoked a warning.
45    
46       . Turning on some more compiler warnings threw up some "shadow" variables
47         and a few more missing casts.
48    
49    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
50       option, a class that contained a single character with a value between 128
51       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
52    
53    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
54       option, a class that contained several characters, but with at least one
55       whose value was between 128 and 255 caused PCRE to crash.
56    
57    
58    Version 4.1 12-Mar-03
59    ---------------------
60    
61    1. Compiling with gcc -pedantic found a couple of places where casts were
62    needed, and a string in dftables.c that was longer than standard compilers are
63    required to support.
64    
65    2. Compiling with Sun's compiler found a few more places where the code could
66    be tidied up in order to avoid warnings.
67    
68    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
69    first of these names is deprecated in the latest Autoconf in favour of the name
70    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
71    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
72    analogy I have changed it to CFLAGS_FOR_BUILD.
73    
74    4. Added -no-undefined to the linking command in the Makefile, because this is
75    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
76    linking step for the pcreposix library.
77    
78    5. PCRE was failing to diagnose the case of two named groups with the same
79    name.
80    
81    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
82    literal character that is needed in the subject for a match, and scans along to
83    ensure that it is present before embarking on the full matching process. This
84    saves time in cases of nested unlimited repeats that are never going to match.
85    Problem: the scan can take a lot of time if the subject is very long (e.g.
86    megabytes), thus penalizing straightforward matches. It is now done only if the
87    amount of subject to be scanned is less than 1000 bytes.
88    
89    7. A lesser problem with the same optimization is that it was recording the
90    first character of an anchored pattern as "needed", thus provoking a search
91    right along the subject, even when the first match of the pattern was going to
92    fail. The "needed" character is now not set for anchored patterns, unless it
93    follows something in the pattern that is of non-fixed length. Thus, it still
94    fulfils its original purpose of finding quick non-matches in cases of nested
95    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
96    
97    
98    Version 4.0 17-Feb-03
99    ---------------------
100    
101    1. If a comment in an extended regex that started immediately after a meta-item
102    extended to the end of string, PCRE compiled incorrect data. This could lead to
103    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
104    
105    2. Moved to autoconf 2.53 and libtool 1.4.2.
106    
107    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
108    the special perltest8 script is no longer needed - all the tests can be run
109    from a single perltest script.
110    
111    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
112    by \s. It has now been removed in PCRE. This means it isn't recognized as
113    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
114    class [:space:] *does* include VT, thereby creating a mess.
115    
116    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
117    space and tab.
118    
119    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
120    its new features into the main test script, reducing the number of scripts.
121    
122    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
123    were backward compatible, and made the (?i) apply to the whole pattern, as if
124    /i were given. Now it behaves more logically, and applies the option setting
125    only to what follows. PCRE has been changed to follow suit. However, if it
126    finds options settings right at the start of the pattern, it extracts them into
127    the global options, as before. Thus, they show up in the info data.
128    
129    8. Added support for the \Q...\E escape sequence. Characters in between are
130    treated as literals. This is slightly different from Perl in that $ and @ are
131    also handled as literals inside the quotes. In Perl, they will cause variable
132    interpolation. Note the following examples:
133    
134        Pattern            PCRE matches      Perl matches
135    
136        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
137        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
138        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
139    
140    For compatibility with Perl, \Q...\E sequences are recognized inside character
141    classes as well as outside them.
142    
143    9. Re-organized 3 code statements in pcretest to avoid "overflow in
144    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
145    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
146    signed/unsigned warnings.
147    
148    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
149    option for pcretest, so I've replaced it by a simple function that does just
150    that job.
151    
152    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
153    "pcregrep -".
154    
155    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
156    Java package. This provides some syntactic sugar for simple cases of what my
157    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
158    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
159    item, you can use this simplified notation. Note that only makes sense with
160    greedy quantifiers. Consequently, the use of the possessive quantifier forces
161    greediness, whatever the setting of the PCRE_UNGREEDY option.
162    
163    13. A change of greediness default within a pattern was not taking effect at
164    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
165    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
166    was abstracted outside.
167    
168    14. PCRE now supports the \G assertion. It is true when the current matching
169    position is at the start point of the match. This differs from \A when the
170    starting offset is non-zero. Used with the /g option of pcretest (or similar
171    code), it works in the same way as it does for Perl's /g option. If all
172    alternatives of a regex begin with \G, the expression is anchored to the start
173    match position, and the "anchored" flag is set in the compiled expression.
174    
175    15. Some bugs concerning the handling of certain option changes within patterns
176    have been fixed. These applied to options other than (?ims). For example,
177    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
178    been the other way round. Some of this was related to change 7 above.
179    
180    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
181    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
182    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
183    POSIX classes only within a class (e.g. /[[:alpha:]]/).
184    
185    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
186    mode. Unlike ".", it always matches newline, whatever the setting of
187    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
188    assertions. Perl allows it, but it doesn't (in general) work because it can't
189    calculate the length of the lookbehind. At least, that's the case for Perl
190    5.8.0 - I've been told they are going to document that it doesn't work in
191    future.
192    
193    18. Added an error diagnosis for escapes that PCRE does not support: these are
194    \L, \l, \N, \P, \p, \U, \u, and \X.
195    
196    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
197    reading past the end of the pattern in cases such as /[abcd/.
198    
199    20. PCRE was getting more memory than necessary for patterns with classes that
200    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
201    
202    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
203    compiling PCRE for use with Virtual Pascal.
204    
205    22. Small fix to the Makefile to make it work properly if the build is done
206    outside the source tree.
207    
208    23. Added a new extension: a condition to go with recursion. If a conditional
209    subpattern starts with (?(R) the "true" branch is used if recursion has
210    happened, whereas the "false" branch is used only at the top level.
211    
212    24. When there was a very long string of literal characters (over 255 bytes
213    without UTF support, over 250 bytes with UTF support), the computation of how
214    much memory was required could be incorrect, leading to segfaults or other
215    strange effects.
216    
217    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
218    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
219    there was a subsequent back reference to those brackets. This meant that, for
220    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
221    possible to check for precisely this case. All we can do is abandon the
222    optimization if .* occurs inside capturing brackets when there are any back
223    references whatsoever. (See below for a better fix that came later.)
224    
225    26. The handling of the optimization for finding the first character of a
226    non-anchored pattern, and for finding a character that is required later in the
227    match were failing in some cases. This didn't break the matching; it just
228    failed to optimize when it could. The way this is done has been re-implemented.
229    
230    27. Fixed typo in error message for invalid (?R item (it said "(?p").
231    
232    28. Added a new feature that provides some of the functionality that Perl
233    provides with (?{...}). The facility is termed a "callout". The way it is done
234    in PCRE is for the caller to provide an optional function, by setting
235    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
236    global variable. By default it is unset, which disables all calling out. To get
237    the function called, the regex must include (?C) at appropriate points. This
238    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
239    This provides a means of identifying different callout points. When PCRE
240    reaches such a point in the regex, if pcre_callout has been set, the external
241    function is called. It is provided with data in a structure called
242    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
243    matching continues; if it returns a non-zero value, the match at the current
244    point fails. However, backtracking will occur if possible. [This was changed
245    later and other features added - see item 49 below.]
246    
247    29. pcretest is upgraded to test the callout functionality. It provides a
248    callout function that displays information. By default, it shows the start of
249    the match and the current position in the text. There are some new data escapes
250    to vary what happens:
251    
252        \C+         in addition, show current contents of captured substrings
253        \C-         do not supply a callout function
254        \C!n        return 1 when callout number n is reached
255        \C!n!m      return 1 when callout number n is reached for the mth time
256    
257    30. If pcregrep was called with the -l option and just a single file name, it
258    output "<stdin>" if a match was found, instead of the file name.
259    
260    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
261    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
262    pcre_exec(). This saves a malloc/free per call. The default value of
263    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
264    when configuring.
265    
266    32. The default maximum size of a compiled pattern is 64K. There have been a
267    few cases of people hitting this limit. The code now uses macros to handle the
268    storing of links as offsets within the compiled pattern. It defaults to 2-byte
269    links, but this can be changed to 3 or 4 bytes by --with-link-size when
270    configuring. Tests 2 and 5 work only with 2-byte links because they output
271    debugging information about compiled patterns.
272    
273    33. Internal code re-arrangements:
274    
275    (a) Moved the debugging function for printing out a compiled regex into
276        its own source file (printint.c) and used #include to pull it into
277        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
278        separate copies.
279    
280    (b) Defined the list of op-code names for debugging as a macro in
281        internal.h so that it is next to the definition of the opcodes.
282    
283    (c) Defined a table of op-code lengths for simpler skipping along compiled
284        code. This is again a macro in internal.h so that it is next to the
285        definition of the opcodes.
286    
287    34. Added support for recursive calls to individual subpatterns, along the
288    lines of Robin Houston's patch (but implemented somewhat differently).
289    
290    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
291    allow it to read and process whole directories in Win32. This code was
292    contributed by Lionel Fourquaux; it has not been tested by me.
293    
294    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
295    used to name a group. Names consist of alphanumerics and underscores, and must
296    be unique. Back references use the syntax (?P=name) and recursive calls use
297    (?P>name) which is a PCRE extension to the Python extension. Groups still have
298    numbers. The function pcre_fullinfo() can be used after compilation to extract
299    a name/number map. There are three relevant calls:
300    
301      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
302      PCRE_INFO_NAMECOUNT            yields the number of entries
303      PCRE_INFO_NAMETABLE            yields a pointer to the map.
304    
305    The map is a vector of fixed-size entries. The size of each entry depends on
306    the length of the longest name used. The first two bytes of each entry are the
307    group number, most significant byte first. There follows the corresponding
308    name, zero terminated. The names are in alphabetical order.
309    
310    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
311    case instead of 255. Making it the same both with and without UTF-8 support
312    means that the same test output works with both.
313    
314    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
315    calling malloc() with a zero argument.
316    
317    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
318    optimization. I've improved things by keeping a bitmap of backreferences with
319    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
320    fact referenced, the optimization can be applied. It is unlikely that a
321    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
322    the match to follow \n) will appear inside brackets with a number greater than
323    31, but if it does, any back reference > 31 suppresses the optimization.
324    
325    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
326    of disabling numbered capturing parentheses. Any opening parenthesis that is
327    not followed by ? behaves as if it were followed by ?: but named parentheses
328    can still be used for capturing (and they will acquire numbers in the usual
329    way).
330    
331    41. Redesigned the return codes from the match() function into yes/no/error so
332    that errors can be passed back from deep inside the nested calls. A malloc
333    failure while inside a recursive subpattern call now causes the
334    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
335    
336    42. It is now possible to set a limit on the number of times the match()
337    function is called in a call to pcre_exec(). This facility makes it possible to
338    limit the amount of recursion and backtracking, though not in a directly
339    obvious way, because the match() function is used in a number of different
340    circumstances. The count starts from zero for each position in the subject
341    string (for non-anchored patterns). The default limit is, for compatibility, a
342    large number, namely 10 000 000. You can change this in two ways:
343    
344    (a) When configuring PCRE before making, you can use --with-match-limit=n
345        to set a default value for the compiled library.
346    
347    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
348        a different value is set. See 45 below.
349    
350    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
351    
352    43. Added a new function pcre_config(int, void *) to enable run-time extraction
353    of things that can be changed at compile time. The first argument specifies
354    what is wanted and the second points to where the information is to be placed.
355    The current list of available information is:
356    
357      PCRE_CONFIG_UTF8
358    
359    The output is an integer that is set to one if UTF-8 support is available;
360    otherwise it is set to zero.
361    
362      PCRE_CONFIG_NEWLINE
363    
364    The output is an integer that it set to the value of the code that is used for
365    newline. It is either LF (10) or CR (13).
366    
367      PCRE_CONFIG_LINK_SIZE
368    
369    The output is an integer that contains the number of bytes used for internal
370    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
371    
372      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
373    
374    The output is an integer that contains the threshold above which the POSIX
375    interface uses malloc() for output vectors. See item 31 above.
376    
377      PCRE_CONFIG_MATCH_LIMIT
378    
379    The output is an unsigned integer that contains the default limit of the number
380    of match() calls in a pcre_exec() execution. See 42 above.
381    
382    44. pcretest has been upgraded by the addition of the -C option. This causes it
383    to extract all the available output from the new pcre_config() function, and to
384    output it. The program then exits immediately.
385    
386    45. A need has arisen to pass over additional data with calls to pcre_exec() in
387    order to support additional features. One way would have been to define
388    pcre_exec2() (for example) with extra arguments, but this would not have been
389    extensible, and would also have required all calls to the original function to
390    be mapped to the new one. Instead, I have chosen to extend the mechanism that
391    is used for passing in "extra" data from pcre_study().
392    
393    The pcre_extra structure is now exposed and defined in pcre.h. It currently
394    contains the following fields:
395    
396      flags         a bitmap indicating which of the following fields are set
397      study_data    opaque data from pcre_study()
398      match_limit   a way of specifying a limit on match() calls for a specific
399                      call to pcre_exec()
400      callout_data  data for callouts (see 49 below)
401    
402    The flag bits are also defined in pcre.h, and are
403    
404      PCRE_EXTRA_STUDY_DATA
405      PCRE_EXTRA_MATCH_LIMIT
406      PCRE_EXTRA_CALLOUT_DATA
407    
408    The pcre_study() function now returns one of these new pcre_extra blocks, with
409    the actual study data pointed to by the study_data field, and the
410    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
411    before. That is, this change is entirely upwards-compatible and requires no
412    change to existing code.
413    
414    If you want to pass in additional data to pcre_exec(), you can either place it
415    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
416    block.
417    
418    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
419    data string contains the escape sequence \M, pcretest calls pcre_exec() several
420    times with different match limits, until it finds the minimum value needed for
421    pcre_exec() to complete. The value is then output. This can be instructive; for
422    most simple matches the number is quite small, but for pathological cases it
423    gets very large very quickly.
424    
425    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
426    returns the size of the data block pointed to by the study_data field in a
427    pcre_extra block, that is, the value that was passed as the argument to
428    pcre_malloc() when PCRE was getting memory in which to place the information
429    created by pcre_study(). The fourth argument should point to a size_t variable.
430    pcretest has been extended so that this information is shown after a successful
431    pcre_study() call when information about the compiled regex is being displayed.
432    
433    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
434    because what follows is always an absolute path. (Later: it turns out that this
435    is more than cosmetic for MinGW, because it doesn't like empty path
436    components.)
437    
438    49. Some changes have been made to the callout feature (see 28 above):
439    
440    (i)  A callout function now has three choices for what it returns:
441    
442           0  =>  success, carry on matching
443         > 0  =>  failure at this point, but backtrack if possible
444         < 0  =>  serious error, return this value from pcre_exec()
445    
446         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
447         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
448         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
449         use by callout functions. It will never be used by PCRE itself.
450    
451    (ii) The pcre_extra structure (see 45 above) has a void * field called
452         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
453         pcre_callout_block structure has a field of the same name. The contents of
454         the field passed in the pcre_extra structure are passed to the callout
455         function in the corresponding field in the callout block. This makes it
456         easier to use the same callout-containing regex from multiple threads. For
457         testing, the pcretest program has a new data escape
458    
459           \C*n        pass the number n (may be negative) as callout_data
460    
461         If the callout function in pcretest receives a non-zero value as
462         callout_data, it returns that value.
463    
464    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
465    there were some redundant $(CFLAGS) in commands that are now specified as
466    $(LINK), which already includes $(CFLAGS).
467    
468    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
469    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
470    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
471    one-byte characters throughout. Note that case-insensitive matching applies
472    only to characters whose values are less than 256. PCRE doesn't support the
473    notion of cases for higher-valued characters.
474    
475    (i)   A character class whose characters are all within 0-255 is handled as
476          a bit map, and the map is inverted for negative classes. Previously, a
477          character > 255 always failed to match such a class; however it should
478          match if the class was a negative one (e.g. [^ab]). This has been fixed.
479    
480    (ii)  A negated character class with a single character < 255 is coded as
481          "not this character" (OP_NOT). This wasn't working properly when the test
482          character was multibyte, either singly or repeated.
483    
484    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
485          mode, for example: \x{100}{2,3}.
486    
487    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
488          singly or repeated) now correctly test multibyte characters. However,
489          PCRE doesn't recognize any characters with values greater than 255 as
490          digits, spaces, or word characters. Such characters always match \D, \S,
491          and \W, and never match \d, \s, or \w.
492    
493    (v)   Classes may now contain characters and character ranges with values
494          greater than 255. For example: [ab\x{100}-\x{400}].
495    
496    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
497          PCRE in UTF-8 mode.
498    
499    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
500    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
501    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
502    value.)
503    
504    53. The single man page has become too large. I have therefore split it up into
505    a number of separate man pages. These also give rise to individual HTML pages;
506    these are now put in a separate directory, and there is an index.html page that
507    lists them all. Some hyperlinking between the pages has been installed.
508    
509    54. Added convenience functions for handling named capturing parentheses.
510    
511    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
512    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
513    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
514    are faulted.
515    
516    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
517    calling configure. These values are used when compiling the dftables.c program
518    which is run to generate the source of the default character tables. They
519    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
520    you will need to set these values.
521    
522    57. Updated the building process for Windows DLL, as provided by Fred Cox.
523    
524    
525    Version 3.9 02-Jan-02
526    ---------------------
527    
528    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
529    
530    2. If --disable-static was given, the building process failed when trying to
531    build pcretest and pcregrep. (For some reason it was using libtool to compile
532    them, which is not right, as they aren't part of the library.)
533    
534    
535    Version 3.8 18-Dec-01
536    ---------------------
537    
538    1. The experimental UTF-8 code was completely screwed up. It was packing the
539    bytes in the wrong order. How dumb can you get?
540    
541    
542    Version 3.7 29-Oct-01
543    ---------------------
544    
545    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
546    This caused pcretest, when used on the test data, to segfault. Unfortunately,
547    this didn't happen under Solaris 8, where I normally test things.
548    
549    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
550    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
551    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
552    this fix an hour or so after the initial 3.7 release.)
553    
554    
555    Version 3.6 23-Oct-01
556    ---------------------
557    
558    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
559    offsets passed as NULL with zero offset count.
560    
561    2. The config.guess and config.sub files had not been updated when I moved to
562    the latest autoconf.
563    
564    
565    Version 3.5 15-Aug-01
566    ---------------------
567    
568    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
569    had been forgotten.
570    
571    2. By using declared but undefined structures, we can avoid using "void"
572    definitions in pcre.h while keeping the internal definitions of the structures
573    private.
574    
575    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
576    user point of view, this means that both static and shared libraries are built
577    by default, but this can be individually controlled. More of the work of
578    handling this static/shared cases is now inside libtool instead of PCRE's make
579    file.
580    
581    4. The pcretest utility is now installed along with pcregrep because it is
582    useful for users (to test regexs) and by doing this, it automatically gets
583    relinked by libtool. The documentation has been turned into a man page, so
584    there are now .1, .txt, and .html versions in /doc.
585    
586    5. Upgrades to pcregrep:
587       (i)   Added long-form option names like gnu grep.
588       (ii)  Added --help to list all options with an explanatory phrase.
589       (iii) Added -r, --recursive to recurse into sub-directories.
590       (iv)  Added -f, --file to read patterns from a file.
591    
592    6. pcre_exec() was referring to its "code" argument before testing that
593    argument for NULL (and giving an error if it was NULL).
594    
595    7. Upgraded Makefile.in to allow for compiling in a different directory from
596    the source directory.
597    
598    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
599    options bits, the pointer it was passed was to an int instead of to an unsigned
600    long int. This mattered only on 64-bit systems.
601    
602    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
603    generated) instead of pcre.in, which it its source. Also made the same change
604    in several of the .c files.
605    
606    10. A new release of gcc defines printf() as a macro, which broke pcretest
607    because it had an ifdef in the middle of a string argument for printf(). Fixed
608    by using separate calls to printf().
609    
610    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
611    script, to force use of CR or LF instead of \n in the source. On non-Unix
612    systems, the value can be set in config.h.
613    
614    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
615    absolute limit. Changed the text of the error message to make this clear, and
616    likewise updated the man page.
617    
618    13. The limit of 99 on the number of capturing subpatterns has been removed.
619    The new limit is 65535, which I hope will not be a "real" limit.
620    
621    
622    Version 3.4 22-Aug-00
623    ---------------------
624    
625    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
626    
627    2. Diagnose condition (?(0) as an error instead of crashing on matching.
628    
629    
630    Version 3.3 01-Aug-00
631    ---------------------
632    
633    1. If an octal character was given, but the value was greater than \377, it
634    was not getting masked to the least significant bits, as documented. This could
635    lead to crashes in some systems.
636    
637    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
638    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
639    
640    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
641    These just pass their arguments on to (pcre_free)(), but they are provided
642    because some uses of PCRE bind it to non-C systems that can call its functions,
643    but cannot call free() or pcre_free() directly.
644    
645    4. Add "make test" as a synonym for "make check". Corrected some comments in
646    the Makefile.
647    
648    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
649    Makefile.
650    
651    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
652    command called pgrep for grepping around the active processes.
653    
654    7. Added the beginnings of support for UTF-8 character strings.
655    
656    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
657    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
658    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
659    out for the ar command.)
660    
661    
662    Version 3.2 12-May-00
663    ---------------------
664    
665    This is purely a bug fixing release.
666    
667    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
668    of ZA. This was just one example of several cases that could provoke this bug,
669    which was introduced by change 9 of version 2.00. The code for breaking
670    infinite loops after an iteration that matches an empty string was't working
671    correctly.
672    
673    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
674    when matched against abbab (for example). After matching an empty string, it
675    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
676    caused it to match further down the string than it should.
677    
678    3. The code contained an inclusion of sys/types.h. It isn't clear why this
679    was there because it doesn't seem to be needed, and it causes trouble on some
680    systems, as it is not a Standard C header. It has been removed.
681    
682    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
683    were reported on the Macintosh. The changes were from
684    
685      while ((c = *(++ptr)) != 0 && c != '\n');
686    to
687      while ((c = *(++ptr)) != 0 && c != '\n') ;
688    
689    Totally extraordinary, but if that's what it takes...
690    
691    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
692    available. Added HAVE_BCOPY and an autoconf test for it; if neither
693    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
694    assumes the way PCRE uses memmove() (always moving upwards).
695    
696    6. PCRE is being used in one environment where strchr() is not available. There
697    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
698    faster code anyway.
699    
700    
701    Version 3.1 09-Feb-00
702    ---------------------
703    
704    The only change in this release is the fixing of some bugs in Makefile.in for
705    the "install" target:
706    
707    (1) It was failing to install pcreposix.h.
708    
709    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
710    
711    
712    Version 3.0 01-Feb-00
713    ---------------------
714    
715    1. Add support for the /+ modifier to perltest (to output $` like it does in
716    pcretest).
717    
718    2. Add support for the /g modifier to perltest.
719    
720    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
721    matches null strings.
722    
723    4. Fix perltest so that it doesn't do unwanted things when fed an empty
724    pattern. Perl treats empty patterns specially - it reuses the most recent
725    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
726    effect.
727    
728    5. The POSIX interface was broken in that it was just handing over the POSIX
729    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
730    required a bigger vector, with some working space on the end. This means that
731    the POSIX wrapper now has to get and free some memory, and copy the results.
732    
733    6. Added some simple autoconf support, placing the test data and the
734    documentation in separate directories, re-organizing some of the
735    information files, and making it build pcre-config (a GNU standard). Also added
736    libtool support for building PCRE as a shared library, which is now the
737    default.
738    
739    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
740    09 are not valid octal constants. Single digits will be used for minor values
741    less than 10.
742    
743    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
744    existing programs that set these in the POSIX interface can use PCRE without
745    modification.
746    
747    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
748    return all that pcre_info() returns, plus additional data. The pcre_info()
749    function is retained for compatibility, but is considered to be obsolete.
750    
751    10. Added experimental recursion feature (?R) to handle one common case that
752    Perl 5.6 will be able to do with (?p{...}).
753    
754    11. Added support for POSIX character classes like [:alpha:], which Perl is
755    adopting.
756    
757    
758    Version 2.08 31-Aug-99
759    ----------------------
760    
761    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
762    trying to match at the startoffset position, but instead was moving forward to
763    the next newline as if a previous match had failed.
764    
765    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
766    and could get into a loop if a null string was matched other than at the start
767    of the subject.
768    
769    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
770    be distinguished at compile time, and for completeness also added PCRE_DATE.
771    
772    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
773    in GnuWin32 environments.
774    
775    
776    Version 2.07 29-Jul-99
777    ----------------------
778    
779    1. The documentation is now supplied in plain text form and HTML as well as in
780    the form of man page sources.
781    
782    2. C++ compilers don't like assigning (void *) values to other pointer types.
783    In particular this affects malloc(). Although there is no problem in Standard
784    C, I've put in casts to keep C++ compilers happy.
785    
786    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
787    should be (const char *).
788    
789    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
790    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
791    However, I haven't made this a standard facility. The documentation doesn't
792    mention it, and the Makefile doesn't support it.
793    
794    5. The Makefile now contains an "install" target, with editable destinations at
795    the top of the file. The pcretest program is not installed.
796    
797    6. pgrep -V now gives the PCRE version number and date.
798    
799    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
800    causing the entire string to be ignored, instead of just the last character.
801    
802    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
803    non-matching string, it can take a very, very long time, even for strings of
804    quite modest length, because of the nested recursion. PCRE now does better in
805    some of these cases. It does this by remembering the last required literal
806    character in the pattern, and pre-searching the subject to ensure it is present
807    before running the real match. In other words, it applies a heuristic to detect
808    some types of certain failure quickly, and in the above example, if presented
809    with a string that has no trailing " it gives "no match" very quickly.
810    
811    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
812    other alternatives are tried instead.
813    
814    
815    Version 2.06 09-Jun-99
816    ----------------------
817    
818    1. Change pcretest's output for amount of store used to show just the code
819    space, because the remainder (the data block) varies in size between 32-bit and
820    64-bit systems.
821    
822    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
823    start matching at. This allows lookbehinds to work when searching for multiple
824    occurrences in a string.
825    
826    3. Added additional options to pcretest for testing multiple occurrences:
827    
828       /+   outputs the rest of the string that follows a match
829       /g   loops for multiple occurrences, using the new startoffset argument
830       /G   loops for multiple occurrences by passing an incremented pointer
831    
832    4. PCRE wasn't doing the "first character" optimization for patterns starting
833    with \b or \B, though it was doing it for other lookbehind assertions. That is,
834    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
835    the letter 'x'. On long subject strings, this gives a significant speed-up.
836    
837    
838    Version 2.05 21-Apr-99
839    ----------------------
840    
841    1. Changed the type of magic_number from int to long int so that it works
842    properly on 16-bit systems.
843    
844    2. Fixed a bug which caused patterns starting with .* not to work correctly
845    when the subject string contained newline characters. PCRE was assuming
846    anchoring for such patterns in all cases, which is not correct because .* will
847    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
848    DOTALL is set at top level; otherwise it knows that patterns starting with .*
849    must be retried after every newline in the subject.
850    
851    
852    Version 2.04 18-Feb-99
853    ----------------------
854    
855    1. For parenthesized subpatterns with repeats whose minimum was zero, the
856    computation of the store needed to hold the pattern was incorrect (too large).
857    If such patterns were nested a few deep, this could multiply and become a real
858    problem.
859    
860    2. Added /M option to pcretest to show the memory requirement of a specific
861    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
862    
863    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
864    compiled in such a way that the backtracking after subsequent failure was
865    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
866    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
867    
868    
869    Version 2.03 02-Feb-99
870    ----------------------
871    
872    1. Fixed typo and small mistake in man page.
873    
874    2. Added 4th condition (GPL supersedes if conflict) and created separate
875    LICENCE file containing the conditions.
876    
877    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
878    Perl, that is the internal \ allows the delimiter to be included in the
879    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
880    the final delimiter, add \ to the end of the pattern (to test the error).
881    
882    4. Added the convenience functions for extracting substrings after a successful
883    match. Updated pcretest to make it able to test these functions.
884    
885    
886    Version 2.02 14-Jan-99
887    ----------------------
888    
889    1. Initialized the working variables associated with each extraction so that
890    their saving and restoring doesn't refer to uninitialized store.
891    
892    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
893    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
894    fix the problem.
895    
896    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
897    calls, and wasn't printing the correct value for compiling calls. Increased the
898    default value of LOOPREPEAT, and the number of significant figures in the
899    times.
900    
901    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
902    
903    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
904    a building problem on Windows NT with a FAT file system.
905    
906    
907    Version 2.01 21-Oct-98
908    ----------------------
909    
910    1. Changed the API for pcre_compile() to allow for the provision of a pointer
911    to character tables built by pcre_maketables() in the current locale. If NULL
912    is passed, the default tables are used.
913    
914    
915    Version 2.00 24-Sep-98
916    ----------------------
917    
918    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
919    it any more.
920    
921    2. Allow quantification of (?>) groups, and make it work correctly.
922    
923    3. The first character computation wasn't working for (?>) groups.
924    
925    4. Correct the implementation of \Z (it is permitted to match on the \n at the
926    end of the subject) and add 5.005's \z, which really does match only at the
927    very end of the subject.
928    
929    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
930    
931    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
932    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
933    localized options. All options to pcre_study() were also removed.
934    
935    7. Add other new features from 5.005:
936    
937       $(?<=           positive lookbehind
938       $(?<!           negative lookbehind
939       (?imsx-imsx)    added the unsetting capability
940                       such a setting is global if at outer level; local otherwise
941       (?imsx-imsx:)   non-capturing groups with option setting
942       (?(cond)re|re)  conditional pattern matching
943    
944       A backreference to itself in a repeated group matches the previous
945       captured string.
946    
947    8. General tidying up of studying (both automatic and via "study")
948    consequential on the addition of new assertions.
949    
950    9. As in 5.005, unlimited repeated groups that could match an empty substring
951    are no longer faulted at compile time. Instead, the loop is forcibly broken at
952    runtime if any iteration does actually match an empty substring.
953    
954    10. Include the RunTest script in the distribution.
955    
956    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
957    discrepancies, some of which were old and were also with respect to 5.004. They
958    have now been fixed.
959    
960    
961    Version 1.09 28-Apr-98
962  ----------------------  ----------------------
963    
964  1. A negated single character class followed by a quantifier with a minimum  1. A negated single character class followed by a quantifier with a minimum

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