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revision 637 by ph10, Sun Jul 24 17:44:12 2011 UTC revision 663 by ph10, Mon Aug 22 14:53:12 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    
30    Version 8.13 16-Aug-2011
31  ------------------------  ------------------------
32    
33  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 46  Version 8.13 30-Apr-2011
46      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
47      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
48      left).      left).
49    
50  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
51      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
52      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
53      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
54    
55  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
56      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
57      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
58      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
59      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
60    
61  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
62      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
63      failure, the offset and reason code are output.      failure, the offset and reason code are output.
64    
65  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
66      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
67      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
68      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
69      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
70      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
71      has been changed.      has been changed.
72    
73  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
74      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
75      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
76      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,
77      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
78      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
79      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
80      (?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.
81    
82  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
83      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
84      using pcre_exec().      using pcre_exec().
85    
86  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
87      discovered and fixed:      discovered and fixed:
88    
89      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
90      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
91      ((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.
92      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
93      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
94    
95  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
96      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
97      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
98    
99  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
100      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
101      ones are added and accidentally left out of pcre_study(), testing should      ones are added and accidentally left out of pcre_study(), testing should
102      pick them up.      pick them up.
103    
104  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
105      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
106      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
107      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
108      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
109      study enabled, and thereby test pcre_study() more easily. All the standard      study enabled, and thereby test pcre_study() more easily. All the standard
110      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
111      "never study" - see 20 below).      "never study" - see 20 below).
112    
113  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
114      restoration of the capturing data to the outer values was not happening      restoration of the capturing data to the outer values was not happening
115      correctly.      correctly.
116    
117  16. If a recursively called subpattern ended with (*ACCEPT) and matched an  16. If a recursively called subpattern ended with (*ACCEPT) and matched an
118      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
119      pattern had matched an empty string, and so incorrectly returned a no      pattern had matched an empty string, and so incorrectly returned a no
120      match.      match.
121    
122  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,
123      and also for the obeyed branch of a conditional subexpression, which used      and also for the obeyed branch of a conditional subexpression, which used
124      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
125      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
126      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
127      two optimizations have therefore been removed.      two optimizations have therefore been removed.
128    
129  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
130      matched two bytes, thus causing the minimum subject length to be      matched two bytes, thus causing the minimum subject length to be
131      incorrectly computed because \R can also match just one byte.      incorrectly computed because \R can also match just one byte.
132    
133  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
134      was incorrectly computed.      was incorrectly computed.
135    
136  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
137      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
138      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
139        identical in both cases.
140    
141  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
142      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.
143    
144  22. When an atomic group that contained a capturing parenthesis was  22. When an atomic group that contained a capturing parenthesis was
145      successfully matched, but the branch in which it appeared failed, the      successfully matched, but the branch in which it appeared failed, the
146      capturing was not being forgotten if a higher numbered group was later      capturing was not being forgotten if a higher numbered group was later
147      captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing      captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
148      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-
149      branched capturing and non-capturing groups, repeated or not, and also to      branched capturing and non-capturing groups, repeated or not, and also to
150      positive assertions (capturing in negative assertions is not well defined      positive assertions (capturing in negative assertions does not happen
151      in PCRE) and also to nested atomic groups.      in PCRE) and also to nested atomic groups.
152    
153  23. Add the ++ qualifier feature to pcretest, to show the remainder of the  23. Add the ++ qualifier feature to pcretest, to show the remainder of the
154      subject after a captured substring (to make it easier to tell which of a      subject after a captured substring, to make it easier to tell which of a
155      number of identical substrings has been captured).      number of identical substrings has been captured.
156    
157  24. The way atomic groups are processed by pcre_exec() has been changed so that  24. The way atomic groups are processed by pcre_exec() has been changed so that
158      if they are repeated, backtracking one repetition now resets captured      if they are repeated, backtracking one repetition now resets captured
159      values correctly. For example, if ((?>(a+)b)+aabab) is matched against      values correctly. For example, if ((?>(a+)b)+aabab) is matched against
160      "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as      "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
161      "aaa". Previously, it would have been "a". As part of this code      "aaa". Previously, it would have been "a". As part of this code
162      refactoring, the way recursive calls are handled has also been changed.      refactoring, the way recursive calls are handled has also been changed.
163    
164  24. If an assertion condition captured any substrings, they were not passed  25. If an assertion condition captured any substrings, they were not passed
165      back unless some other capturing happened later. For example, if      back unless some other capturing happened later. For example, if
166      (?(?=(a))a) was matched against "a", no capturing was returned.      (?(?=(a))a) was matched against "a", no capturing was returned.
167    
168  25. When studying a pattern that contained subroutine calls or assertions,  26. When studying a pattern that contained subroutine calls or assertions,
169      the code for finding the minimum length of a possible match was handling      the code for finding the minimum length of a possible match was handling
170      direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where      direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
171      group 1 called group 2 while simultaneously a separate group 2 called group      group 1 called group 2 while simultaneously a separate group 2 called group
172      1). A stack overflow occurred in this case. I have fixed this by limiting      1). A stack overflow occurred in this case. I have fixed this by limiting
173      the recursion depth to 10.      the recursion depth to 10.
174    
175  26. Updated RunTest.bat in the distribution to the version supplied by Tom  27. Updated RunTest.bat in the distribution to the version supplied by Tom
176      Fortmann. This supports explicit test numbers on the command line, and has      Fortmann. This supports explicit test numbers on the command line, and has
177      argument validation and error reporting.      argument validation and error reporting.
178    
179  27. An instance of \X with an unlimited repeat could fail if at any point the  28. An instance of \X with an unlimited repeat could fail if at any point the
180      first character it looked at was a mark character.      first character it looked at was a mark character.
181    
182  28. Some minor code refactoring concerning Unicode properties and scripts  29. Some minor code refactoring concerning Unicode properties and scripts
183      should reduce the stack requirement of match() slightly.      should reduce the stack requirement of match() slightly.
184    
185  29. Added the '=' option to pcretest to check the setting of unused capturing  30. Added the '=' option to pcretest to check the setting of unused capturing
186      slots at the end of the pattern, which are documented as being -1, but are      slots at the end of the pattern, which are documented as being -1, but are
187      not included in the return count.      not included in the return count.
188    
189  30. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE  31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
190      compiled something random. Now it gives a compile-time error (as does      compiled something random. Now it gives a compile-time error (as does
191      Perl).      Perl).
192    
193  31. A *MARK encountered during the processing of a positive assertion is now  32. A *MARK encountered during the processing of a positive assertion is now
194      recorded and passed back (compatible with Perl).      recorded and passed back (compatible with Perl).
195    
196  32. If --only-matching or --colour was set on a pcregrep call whose pattern  33. If --only-matching or --colour was set on a pcregrep call whose pattern
197      had alternative anchored branches, the search for a second match in a line      had alternative anchored branches, the search for a second match in a line
198      was done as if at the line start. Thus, for example, /^01|^02/ incorrectly      was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
199      matched the line "0102" twice. The same bug affected patterns that started      matched the line "0102" twice. The same bug affected patterns that started
200      with a backwards assertion. For example /\b01|\b02/ also matched "0102"      with a backwards assertion. For example /\b01|\b02/ also matched "0102"
201      twice.      twice.
202    
203  33. Previously, PCRE did not allow quantification of assertions. However, Perl  34. Previously, PCRE did not allow quantification of assertions. However, Perl
204      does, and because of capturing effects, quantifying parenthesized      does, and because of capturing effects, quantifying parenthesized
205      assertions may at times be useful. Quantifiers are now allowed for      assertions may at times be useful. Quantifiers are now allowed for
206      parenthesized assertions.      parenthesized assertions.
207    
208    35. A minor code tidy in pcre_compile() when checking options for \R usage.
209    
210    36. \g was being checked for fancy things in a character class, when it should
211        just be a literal "g".
212    
213    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
214        appearance of a nested POSIX class supersedes an apparent external class.
215        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
216        unescaped square brackets may also appear as part of class names. For
217        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
218        more like Perl. (But see 8.20/1 above.)
219    
220    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
221        was because it thought it was \N{name}, which is not supported).
222    
223    39. Add minix to OS list not supporting the -S option in pcretest.
224    
225    40. PCRE tries to detect cases of infinite recursion at compile time, but it
226        cannot analyze patterns in sufficient detail to catch mutual recursions
227        such as ((?1))((?2)). There is now a runtime test that gives an error if a
228        subgroup is called recursively as a subpattern for a second time at the
229        same position in the subject string. In previous releases this might have
230        been caught by the recursion limit, or it might have run out of stack.
231    
232    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
233        happen only once. PCRE was, however incorrectly giving a compile time error
234        "recursive call could loop indefinitely" because it cannot analyze the
235        pattern in sufficient detail. The compile time test no longer happens when
236        PCRE is compiling a conditional subpattern, but actual runaway loops are
237        now caught at runtime (see 40 above).
238    
239    42. It seems that Perl allows any characters other than a closing parenthesis
240        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
241        has been changed to be the same.
242    
243    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
244        as not to get warnings when autogen.sh is called. Also changed
245        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
246    
247    44. To help people who use pcregrep to scan files containing exceedingly long
248        lines, the following changes have been made:
249    
250        (a) The default value of the buffer size parameter has been increased from
251            8K to 20K. (The actual buffer used is three times this size.)
252    
253        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
254            PCRE is built.
255    
256        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
257            to be set at run time.
258    
259        (d) Numerical values in pcregrep options can be followed by K or M, for
260            example --buffer-size=50K.
261    
262        (e) If a line being scanned overflows pcregrep's buffer, an error is now
263            given and the return code is set to 2.
264    
265    45. Add a pointer to the latest mark to the callout data block.
266    
267    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
268        partial match of an empty string instead of no match. This was specific to
269        the use of ".".
270    
271    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
272        complete match instead of a partial match. This bug was dependent on both
273        the PCRE_UTF8 and PCRE_DOTALL options being set.
274    
275    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
276        starting byte set, because \b was not being ignored.
277    
278    
279  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
280  ------------------------  ------------------------

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