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revision 614 by ph10, Sat Jul 9 10:48:16 2011 UTC revision 687 by ph10, Tue Sep 6 16:09:43 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. When this is
31       done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
32       runtime --no-jit option is given.
33    
34    5. When the number of matches in a pcre_dfa_exec() run exactly filled the
35       ovector, the return from the function was zero, implying that there were
36       other matches that did not fit. The correct "exactly full" value is now
37       returned.
38    
39    6. If a subpattern that was called recursively or as a subroutine contained
40       (*PRUNE) or any other control that caused it to give a non-standard return,
41       invalid errors such as "Error -26 (nested recursion at the same subject
42       position)" or even infinite loops could occur.
43    
44    
45    Version 8.13 16-Aug-2011
46  ------------------------  ------------------------
47    
48  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 61  Version 8.13 30-Apr-2011
61      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
62      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
63      left).      left).
64    
65  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
66      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
67      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
68      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
69    
70  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
71      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
72      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
73      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
74      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
75    
76  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
77      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
78      failure, the offset and reason code are output.      failure, the offset and reason code are output.
79    
80  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
81      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
82      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
83      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
84      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
85      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
86      has been changed.      has been changed.
87    
88  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
89      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
90      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
91      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,
92      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
93      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
94      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
95      (?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.
96    
97  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
98      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
99      using pcre_exec().      using pcre_exec().
100    
101  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
102      discovered and fixed:      discovered and fixed:
103    
104      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
105      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
106      ((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.
107      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
108      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
109    
110  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
111      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
112      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
113    
114  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
115      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
116      ones are added and accidentally left out of pcre_study(), testing should      ones are added and accidentally left out of pcre_study(), testing should
117      pick them up.      pick them up.
118    
119  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
120      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
121      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
122      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
123      using it. It makes it easier to run collections of tests with and without      using it. It makes it easier to run collections of tests with and without
124      study enabled, and thereby test pcre_study() more easily. All the standard      study enabled, and thereby test pcre_study() more easily. All the standard
125      tests are now run with and without -s (but some patterns can be marked as      tests are now run with and without -s (but some patterns can be marked as
126      "never study" - see 20 below).      "never study" - see 20 below).
127    
128  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
129      restoration of the capturing data to the outer values was not happening      restoration of the capturing data to the outer values was not happening
130      correctly.      correctly.
131    
132  16. If a recursively called subpattern ended with (*ACCEPT) and matched an  16. If a recursively called subpattern ended with (*ACCEPT) and matched an
133      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
134      pattern had matched an empty string, and so incorrectly returned a no      pattern had matched an empty string, and so incorrectly returned a no
135      match.      match.
136    
137  17. There was optimizing code for the last branch of non-capturing parentheses,  17. There was optimizing code for the last branch of non-capturing parentheses,
138      and also for the obeyed branch of a conditional subexpression, which used      and also for the obeyed branch of a conditional subexpression, which used
139      tail recursion to cut down on stack usage. Unfortunately, not that there is      tail recursion to cut down on stack usage. Unfortunately, now that there is
140      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
141      no longer possible because the return has to be checked for (*THEN). These      no longer possible because the return has to be checked for (*THEN). These
142      two optimizations have therefore been removed.      two optimizations have therefore been removed.
143    
144  18. If a pattern containing \R was studied, it was assumed that \R always  18. If a pattern containing \R was studied, it was assumed that \R always
145      matched two bytes, thus causing the minimum subject length to be      matched two bytes, thus causing the minimum subject length to be
146      incorrectly computed because \R can also match just one byte.      incorrectly computed because \R can also match just one byte.
147    
148  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
149      was incorrectly computed.      was incorrectly computed.
150    
151  20. If /S is present twice on a test pattern in pcretest input, it *disables*  20. If /S is present twice on a test pattern in pcretest input, it now
152      studying, thereby overriding the use of -s on the command line. This is      *disables* studying, thereby overriding the use of -s on the command line
153      necessary for one or two tests to keep the output identical in both cases.      (see 14 above). This is necessary for one or two tests to keep the output
154        identical in both cases.
155    
156  21. When (*ACCEPT) was used in an assertion that matched an empty string and  21. When (*ACCEPT) was used in an assertion that matched an empty string and
157      PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.      PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
158    
159  22. When an atomic group that contained a capturing parenthesis was  22. When an atomic group that contained a capturing parenthesis was
160      successfully matched, but the branch in which it appeared failed, the      successfully matched, but the branch in which it appeared failed, the
161      capturing was not being forgotten if a higher numbered group was later      capturing was not being forgotten if a higher numbered group was later
162      captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing      captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
163      group 1 to "a", when in fact it should be unset. This applied to multi-      group 1 to "a", when in fact it should be unset. This applied to multi-
164      branched capturing and non-capturing groups, repeated or not, and also to      branched capturing and non-capturing groups, repeated or not, and also to
165      positive assertions (capturing in negative assertions is not well defined      positive assertions (capturing in negative assertions does not happen
166      in PCRE) and also to nested atomic groups.      in PCRE) and also to nested atomic groups.
167    
168    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
169        subject after a captured substring, to make it easier to tell which of a
170        number of identical substrings has been captured.
171    
172    24. The way atomic groups are processed by pcre_exec() has been changed so that
173        if they are repeated, backtracking one repetition now resets captured
174        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
175        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
176        "aaa". Previously, it would have been "a". As part of this code
177        refactoring, the way recursive calls are handled has also been changed.
178    
179    25. If an assertion condition captured any substrings, they were not passed
180        back unless some other capturing happened later. For example, if
181        (?(?=(a))a) was matched against "a", no capturing was returned.
182    
183    26. When studying a pattern that contained subroutine calls or assertions,
184        the code for finding the minimum length of a possible match was handling
185        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
186        group 1 called group 2 while simultaneously a separate group 2 called group
187        1). A stack overflow occurred in this case. I have fixed this by limiting
188        the recursion depth to 10.
189    
190    27. Updated RunTest.bat in the distribution to the version supplied by Tom
191        Fortmann. This supports explicit test numbers on the command line, and has
192        argument validation and error reporting.
193    
194    28. An instance of \X with an unlimited repeat could fail if at any point the
195        first character it looked at was a mark character.
196    
197    29. Some minor code refactoring concerning Unicode properties and scripts
198        should reduce the stack requirement of match() slightly.
199    
200    30. Added the '=' option to pcretest to check the setting of unused capturing
201        slots at the end of the pattern, which are documented as being -1, but are
202        not included in the return count.
203    
204    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
205        compiled something random. Now it gives a compile-time error (as does
206        Perl).
207    
208    32. A *MARK encountered during the processing of a positive assertion is now
209        recorded and passed back (compatible with Perl).
210    
211    33. If --only-matching or --colour was set on a pcregrep call whose pattern
212        had alternative anchored branches, the search for a second match in a line
213        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
214        matched the line "0102" twice. The same bug affected patterns that started
215        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
216        twice.
217    
218    34. Previously, PCRE did not allow quantification of assertions. However, Perl
219        does, and because of capturing effects, quantifying parenthesized
220        assertions may at times be useful. Quantifiers are now allowed for
221        parenthesized assertions.
222    
223    35. A minor code tidy in pcre_compile() when checking options for \R usage.
224    
225    36. \g was being checked for fancy things in a character class, when it should
226        just be a literal "g".
227    
228    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
229        appearance of a nested POSIX class supersedes an apparent external class.
230        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
231        unescaped square brackets may also appear as part of class names. For
232        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
233        more like Perl. (But see 8.20/1 above.)
234    
235    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
236        was because it thought it was \N{name}, which is not supported).
237    
238    39. Add minix to OS list not supporting the -S option in pcretest.
239    
240    40. PCRE tries to detect cases of infinite recursion at compile time, but it
241        cannot analyze patterns in sufficient detail to catch mutual recursions
242        such as ((?1))((?2)). There is now a runtime test that gives an error if a
243        subgroup is called recursively as a subpattern for a second time at the
244        same position in the subject string. In previous releases this might have
245        been caught by the recursion limit, or it might have run out of stack.
246    
247    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
248        happen only once. PCRE was, however incorrectly giving a compile time error
249        "recursive call could loop indefinitely" because it cannot analyze the
250        pattern in sufficient detail. The compile time test no longer happens when
251        PCRE is compiling a conditional subpattern, but actual runaway loops are
252        now caught at runtime (see 40 above).
253    
254    42. It seems that Perl allows any characters other than a closing parenthesis
255        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
256        has been changed to be the same.
257    
258    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
259        as not to get warnings when autogen.sh is called. Also changed
260        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
261    
262    44. To help people who use pcregrep to scan files containing exceedingly long
263        lines, the following changes have been made:
264    
265        (a) The default value of the buffer size parameter has been increased from
266            8K to 20K. (The actual buffer used is three times this size.)
267    
268        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
269            PCRE is built.
270    
271        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
272            to be set at run time.
273    
274        (d) Numerical values in pcregrep options can be followed by K or M, for
275            example --buffer-size=50K.
276    
277        (e) If a line being scanned overflows pcregrep's buffer, an error is now
278            given and the return code is set to 2.
279    
280    45. Add a pointer to the latest mark to the callout data block.
281    
282    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
283        partial match of an empty string instead of no match. This was specific to
284        the use of ".".
285    
286    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
287        complete match instead of a partial match. This bug was dependent on both
288        the PCRE_UTF8 and PCRE_DOTALL options being set.
289    
290    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
291        starting byte set, because \b was not being ignored.
292    
293    
294  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011

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