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revision 608 by ph10, Sun Jun 12 16:25:55 2011 UTC revision 672 by ph10, Tue Aug 23 16:45:55 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.13 30-Apr-2011  Version 8.20
5    ------------
6    
7    1. Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
8       a POSIX class. After further experiments with Perl, which convinced me that
9       Perl has bugs and confusions, a closing square bracket is no longer allowed
10       in a POSIX name.
11    
12    2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured
13       substring, but while checking the failing first alternative, substring 1 is
14       temporarily captured. If the output vector supplied to pcre_exec() was not
15       big enough for this capture, the yield of the function was still zero
16       ("insufficient space for captured substrings"). This cannot be totally fixed
17       without adding another stack variable, which seems a lot of expense for a
18       edge case. However, I have improved the situation in cases such as
19       /(a)(b)x|abc/ matched against "abc", where the return code indicates that
20       fewer than the maximum number of slots in the ovector have been set.
21    
22    3. Related to (2) above: when there are more back references in a pattern than
23       slots in the output vector, pcre_exec() uses temporary memory during
24       matching, and copies in the captures as far as possible afterwards. It was
25       using the entire output vector, but this conflicts with the specification
26       that only 2/3 is used for passing back captured substrings. Now it uses only
27       the first 2/3, for compatibility. This is, of course, another edge case.
28    
29    4. Zoltan Herczeg's just-in-time compiler support has been integrated into the
30       main code base, and can be used by building with --enable-jit.
31    
32    
33    Version 8.13 16-Aug-2011
34  ------------------------  ------------------------
35    
36  1.  The Unicode data tables have been updated to Unicode 6.0.0.  1.  The Unicode data tables have been updated to Unicode 6.0.0.
# Line 20  Version 8.13 30-Apr-2011 Line 49  Version 8.13 30-Apr-2011
49      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
50      2-byte code at the end of the subject (it thought there wasn't enough data      2-byte code at the end of the subject (it thought there wasn't enough data
51      left).      left).
52    
53  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
54      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
55      as the output vector has at least 2 elements. The offset of the start of      as the output vector has at least 2 elements. The offset of the start of
56      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
57    
58  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
59      now returned is for the first byte of the failing character, instead of the      now returned is for the first byte of the failing character, instead of the
60      last byte inspected. This is an incompatible change, but I hope it is small      last byte inspected. This is an incompatible change, but I hope it is small
61      enough not to be a problem. It makes the returned offset consistent with      enough not to be a problem. It makes the returned offset consistent with
62      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
63    
64  7.  pcretest now gives a text phrase as well as the error number when  7.  pcretest now gives a text phrase as well as the error number when
65      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
66      failure, the offset and reason code are output.      failure, the offset and reason code are output.
67    
68  8.  When \R was used with a maximizing quantifier it failed to skip backwards  8.  When \R was used with a maximizing quantifier it failed to skip backwards
69      over a \r\n pair if the subsequent match failed. Instead, it just skipped      over a \r\n pair if the subsequent match failed. Instead, it just skipped
70      back over a single character (\n). This seems wrong (because it treated the      back over a single character (\n). This seems wrong (because it treated the
71      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
72      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
73      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
74      has been changed.      has been changed.
75    
76  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
77      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
78      time (the PCRE_DOTALL option was changed this way some time ago: version      time (the PCRE_DOTALL option was changed this way some time ago: version
79      7.7 change 16). This has made it possible to abolish the OP_OPT op code,      7.7 change 16). This has made it possible to abolish the OP_OPT op code,
80      which was always a bit of a fudge. It also means that there is one less      which was always a bit of a fudge. It also means that there is one less
81      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
82      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
83      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
84    
85  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
86      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
87      using pcre_exec().      using pcre_exec().
88    
89  11. While implementing 10, a number of bugs in the handling of groups were  11. While implementing 10, a number of bugs in the handling of groups were
90      discovered and fixed:      discovered and fixed:
91    
92      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
93      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
94      ((a|)+)+  did not notice that the outer group could match an empty string.      ((a|)+)+  did not notice that the outer group could match an empty string.
95      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
96      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
97    
98  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
99      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
100      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
101    
102  13. Be more explicit in pcre_study() instead of relying on "default" for  13. Be more explicit in pcre_study() instead of relying on "default" for
103      opcodes that mean there is no starting character; this means that when new      opcodes that mean there is no starting character; this means that when new
104      ones are added and accidentally left out of pcre_study(), testing should      ones are added and accidentally left out of pcre_study(), testing should
105      pick them up.      pick them up.
106    
107  14. The -s option of pcretest has been documented for ages as being an old  14. The -s option of pcretest has been documented for ages as being an old
108      synonym of -m (show memory usage). I have changed it to mean "force study      synonym of -m (show memory usage). I have changed it to mean "force study
109      for every regex", that is, assume /S for every regex. This is similar to -i      for every regex", that is, assume /S for every regex. This is similar to -i
110      and -d etc. It's slightly incompatible, but I'm hoping nobody is still      and -d etc. It's slightly incompatible, but I'm hoping nobody is still
111      using it. It makes it easier to run collection of tests with study enabled,      using it. It makes it easier to run collections of tests with and without
112      and thereby test pcre_study() more easily.      study enabled, and thereby test pcre_study() more easily. All the standard
113        tests are now run with and without -s (but some patterns can be marked as
114        "never study" - see 20 below).
115    
116  15. When (*ACCEPT) was used in a subpattern that was called recursively, the  15. When (*ACCEPT) was used in a subpattern that was called recursively, the
117      restoration of the capturing data to the outer values was not happening      restoration of the capturing data to the outer values was not happening
118      correctly.      correctly.
119    
120  16. If a recursively called subpattern ended with (*ACCEPT) and matched an  16. If a recursively called subpattern ended with (*ACCEPT) and matched an
121      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
122      pattern had matched an empty string, and so incorrectly returned a no      pattern had matched an empty string, and so incorrectly returned a no
123      match.      match.
124    
125    17. There was optimizing code for the last branch of non-capturing parentheses,
126        and also for the obeyed branch of a conditional subexpression, which used
127        tail recursion to cut down on stack usage. Unfortunately, now that there is
128        the possibility of (*THEN) occurring in these branches, tail recursion is
129        no longer possible because the return has to be checked for (*THEN). These
130        two optimizations have therefore been removed.
131    
132    18. If a pattern containing \R was studied, it was assumed that \R always
133        matched two bytes, thus causing the minimum subject length to be
134        incorrectly computed because \R can also match just one byte.
135    
136    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
137        was incorrectly computed.
138    
139    20. If /S is present twice on a test pattern in pcretest input, it now
140        *disables* studying, thereby overriding the use of -s on the command line
141        (see 14 above). This is necessary for one or two tests to keep the output
142        identical in both cases.
143    
144    21. When (*ACCEPT) was used in an assertion that matched an empty string and
145        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
146    
147    22. When an atomic group that contained a capturing parenthesis was
148        successfully matched, but the branch in which it appeared failed, the
149        capturing was not being forgotten if a higher numbered group was later
150        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
151        group 1 to "a", when in fact it should be unset. This applied to multi-
152        branched capturing and non-capturing groups, repeated or not, and also to
153        positive assertions (capturing in negative assertions does not happen
154        in PCRE) and also to nested atomic groups.
155    
156    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
157        subject after a captured substring, to make it easier to tell which of a
158        number of identical substrings has been captured.
159    
160    24. The way atomic groups are processed by pcre_exec() has been changed so that
161        if they are repeated, backtracking one repetition now resets captured
162        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
163        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
164        "aaa". Previously, it would have been "a". As part of this code
165        refactoring, the way recursive calls are handled has also been changed.
166    
167    25. If an assertion condition captured any substrings, they were not passed
168        back unless some other capturing happened later. For example, if
169        (?(?=(a))a) was matched against "a", no capturing was returned.
170    
171    26. When studying a pattern that contained subroutine calls or assertions,
172        the code for finding the minimum length of a possible match was handling
173        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
174        group 1 called group 2 while simultaneously a separate group 2 called group
175        1). A stack overflow occurred in this case. I have fixed this by limiting
176        the recursion depth to 10.
177    
178    27. Updated RunTest.bat in the distribution to the version supplied by Tom
179        Fortmann. This supports explicit test numbers on the command line, and has
180        argument validation and error reporting.
181    
182    28. An instance of \X with an unlimited repeat could fail if at any point the
183        first character it looked at was a mark character.
184    
185    29. Some minor code refactoring concerning Unicode properties and scripts
186        should reduce the stack requirement of match() slightly.
187    
188    30. Added the '=' option to pcretest to check the setting of unused capturing
189        slots at the end of the pattern, which are documented as being -1, but are
190        not included in the return count.
191    
192    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
193        compiled something random. Now it gives a compile-time error (as does
194        Perl).
195    
196    32. A *MARK encountered during the processing of a positive assertion is now
197        recorded and passed back (compatible with Perl).
198    
199    33. If --only-matching or --colour was set on a pcregrep call whose pattern
200        had alternative anchored branches, the search for a second match in a line
201        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
202        matched the line "0102" twice. The same bug affected patterns that started
203        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
204        twice.
205    
206    34. Previously, PCRE did not allow quantification of assertions. However, Perl
207        does, and because of capturing effects, quantifying parenthesized
208        assertions may at times be useful. Quantifiers are now allowed for
209        parenthesized assertions.
210    
211    35. A minor code tidy in pcre_compile() when checking options for \R usage.
212    
213    36. \g was being checked for fancy things in a character class, when it should
214        just be a literal "g".
215    
216    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
217        appearance of a nested POSIX class supersedes an apparent external class.
218        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
219        unescaped square brackets may also appear as part of class names. For
220        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
221        more like Perl. (But see 8.20/1 above.)
222    
223    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
224        was because it thought it was \N{name}, which is not supported).
225    
226    39. Add minix to OS list not supporting the -S option in pcretest.
227    
228    40. PCRE tries to detect cases of infinite recursion at compile time, but it
229        cannot analyze patterns in sufficient detail to catch mutual recursions
230        such as ((?1))((?2)). There is now a runtime test that gives an error if a
231        subgroup is called recursively as a subpattern for a second time at the
232        same position in the subject string. In previous releases this might have
233        been caught by the recursion limit, or it might have run out of stack.
234    
235    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
236        happen only once. PCRE was, however incorrectly giving a compile time error
237        "recursive call could loop indefinitely" because it cannot analyze the
238        pattern in sufficient detail. The compile time test no longer happens when
239        PCRE is compiling a conditional subpattern, but actual runaway loops are
240        now caught at runtime (see 40 above).
241    
242    42. It seems that Perl allows any characters other than a closing parenthesis
243        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
244        has been changed to be the same.
245    
246    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
247        as not to get warnings when autogen.sh is called. Also changed
248        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
249    
250    44. To help people who use pcregrep to scan files containing exceedingly long
251        lines, the following changes have been made:
252    
253        (a) The default value of the buffer size parameter has been increased from
254            8K to 20K. (The actual buffer used is three times this size.)
255    
256        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
257            PCRE is built.
258    
259        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
260            to be set at run time.
261    
262        (d) Numerical values in pcregrep options can be followed by K or M, for
263            example --buffer-size=50K.
264    
265        (e) If a line being scanned overflows pcregrep's buffer, an error is now
266            given and the return code is set to 2.
267    
268    45. Add a pointer to the latest mark to the callout data block.
269    
270    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
271        partial match of an empty string instead of no match. This was specific to
272        the use of ".".
273    
274    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
275        complete match instead of a partial match. This bug was dependent on both
276        the PCRE_UTF8 and PCRE_DOTALL options being set.
277    
278    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
279        starting byte set, because \b was not being ignored.
280    
281    
282  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
283  ------------------------  ------------------------

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