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ChangeLog for PCRE |
ChangeLog for PCRE |
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Version 7.1 05-Mar-07 |
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1. Applied Bob Rossi and Daniel G's patches to convert the build system to one |
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that is more "standard", making use of automake and other autotools. There |
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is some re-arrangement of the files and adjustment of comments consequent |
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on this. |
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2. Part of the patch fixed a problem with the pcregrep tests. The test of -r |
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for recursive directory scanning broke on some systems because the files |
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are not scanned in any specific order and on different systems the order |
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was different. A call to "sort" has been inserted into RunGrepTest for the |
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approprate test as a short-term fix. In the longer term there may be an |
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alternative. |
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3. I had an email from Eric Raymond about problems translating some of PCRE's |
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man pages to HTML (despite the fact that I distribute HTML pages, some |
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people do their own conversions for various reasons). The problems |
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concerned the use of low-level troff macros .br and .in. I have therefore |
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removed all such uses from the man pages (some were redundant, some could |
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be replaced by .nf/.fi pairs). The maintain/132html script that I use to |
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generate HTML has been updated to handle .nf/.fi and to complain if it |
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encounters .br or .in. |
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4. Updated comments in configure.ac that get placed in config.h.in and also |
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arranged for config.h to be included in the distribution, for the benefit |
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of those who have to compile without Autotools (compare pcre.h). |
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Version 7.0 19-Dec-06 |
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--------------------- |
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1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by |
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moving to gcc 4.1.1. |
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2. The -S option for pcretest uses setrlimit(); I had omitted to #include |
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sys/time.h, which is documented as needed for this function. It doesn't |
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seem to matter on Linux, but it showed up on some releases of OS X. |
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3. It seems that there are systems where bytes whose values are greater than |
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127 match isprint() in the "C" locale. The "C" locale should be the |
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default when a C program starts up. In most systems, only ASCII printing |
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characters match isprint(). This difference caused the output from pcretest |
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to vary, making some of the tests fail. I have changed pcretest so that: |
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(a) When it is outputting text in the compiled version of a pattern, bytes |
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other than 32-126 are always shown as hex escapes. |
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(b) When it is outputting text that is a matched part of a subject string, |
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it does the same, unless a different locale has been set for the match |
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(using the /L modifier). In this case, it uses isprint() to decide. |
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4. Fixed a major bug that caused incorrect computation of the amount of memory |
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required for a compiled pattern when options that changed within the |
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pattern affected the logic of the preliminary scan that determines the |
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length. The relevant options are -x, and -i in UTF-8 mode. The result was |
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that the computed length was too small. The symptoms of this bug were |
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either the PCRE error "internal error: code overflow" from pcre_compile(), |
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or a glibc crash with a message such as "pcretest: free(): invalid next |
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size (fast)". Examples of patterns that provoked this bug (shown in |
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pcretest format) are: |
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/(?-x: )/x |
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/(?x)(?-x: \s*#\s*)/ |
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/((?i)[\x{c0}])/8 |
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/(?i:[\x{c0}])/8 |
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HOWEVER: Change 17 below makes this fix obsolete as the memory computation |
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is now done differently. |
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5. Applied patches from Google to: (a) add a QuoteMeta function to the C++ |
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wrapper classes; (b) implement a new function in the C++ scanner that is |
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more efficient than the old way of doing things because it avoids levels of |
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recursion in the regex matching; (c) add a paragraph to the documentation |
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for the FullMatch() function. |
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6. The escape sequence \n was being treated as whatever was defined as |
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"newline". Not only was this contrary to the documentation, which states |
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that \n is character 10 (hex 0A), but it also went horribly wrong when |
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"newline" was defined as CRLF. This has been fixed. |
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7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c) |
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was being set to -1 for the "end of line" case (supposedly a value that no |
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character can have). Though this value is never used (the check for end of |
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line is "zero bytes in current character"), it caused compiler complaints. |
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I've changed it to 0xffffffff. |
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8. In pcre_version.c, the version string was being built by a sequence of |
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C macros that, in the event of PCRE_PRERELEASE being defined as an empty |
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string (as it is for production releases) called a macro with an empty |
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argument. The C standard says the result of this is undefined. The gcc |
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compiler treats it as an empty string (which was what was wanted) but it is |
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reported that Visual C gives an error. The source has been hacked around to |
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avoid this problem. |
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9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows |
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builds of pcretest, and changed the call to _setmode() to use _O_BINARY |
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instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all |
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of them did). |
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10. Originally, pcretest opened its input and output without "b"; then I was |
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told that "b" was needed in some environments, so it was added for release |
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5.0 to both the input and output. (It makes no difference on Unix-like |
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systems.) Later I was told that it is wrong for the input on Windows. I've |
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now abstracted the modes into two macros, to make it easier to fiddle with |
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them, and removed "b" from the input mode under Windows. |
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11. Added pkgconfig support for the C++ wrapper library, libpcrecpp. |
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12. Added -help and --help to pcretest as an official way of being reminded |
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of the options. |
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13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in |
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and pcrecpp.cc because they annoy compilers at high warning levels. |
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14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop. |
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15. Fixed an occurrence of == in configure.ac that should have been = (shell |
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scripts are not C programs :-) and which was not noticed because it works |
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on Linux. |
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16. pcretest is supposed to handle any length of pattern and data line (as one |
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line or as a continued sequence of lines) by extending its input buffer if |
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necessary. This feature was broken for very long pattern lines, leading to |
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a string of junk being passed to pcre_compile() if the pattern was longer |
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than about 50K. |
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17. I have done a major re-factoring of the way pcre_compile() computes the |
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amount of memory needed for a compiled pattern. Previously, there was code |
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that made a preliminary scan of the pattern in order to do this. That was |
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OK when PCRE was new, but as the facilities have expanded, it has become |
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harder and harder to keep it in step with the real compile phase, and there |
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have been a number of bugs (see for example, 4 above). I have now found a |
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cunning way of running the real compile function in a "fake" mode that |
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enables it to compute how much memory it would need, while actually only |
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ever using a few hundred bytes of working memory and without too many |
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tests of the mode. This should make future maintenance and development |
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easier. A side effect of this work is that the limit of 200 on the nesting |
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depth of parentheses has been removed (though this was never a serious |
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limitation, I suspect). However, there is a downside: pcre_compile() now |
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runs more slowly than before (30% or more, depending on the pattern). I |
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hope this isn't a big issue. There is no effect on runtime performance. |
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18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a |
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newline (only possible for the last line of a file) and it was a |
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pattern that set a locale (followed by /Lsomething), pcretest crashed. |
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19. Added additional timing features to pcretest. (1) The -tm option now times |
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matching only, not compiling. (2) Both -t and -tm can be followed, as a |
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separate command line item, by a number that specifies the number of |
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repeats to use when timing. The default is 50000; this gives better |
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precision, but takes uncomfortably long for very large patterns. |
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20. Extended pcre_study() to be more clever in cases where a branch of a |
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subpattern has no definite first character. For example, (a*|b*)[cd] would |
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previously give no result from pcre_study(). Now it recognizes that the |
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first character must be a, b, c, or d. |
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21. There was an incorrect error "recursive call could loop indefinitely" if |
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a subpattern (or the entire pattern) that was being tested for matching an |
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empty string contained only one non-empty item after a nested subpattern. |
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For example, the pattern (?>\x{100}*)\d(?R) provoked this error |
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incorrectly, because the \d was being skipped in the check. |
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22. The pcretest program now has a new pattern option /B and a command line |
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option -b, which is equivalent to adding /B to every pattern. This causes |
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it to show the compiled bytecode, without the additional information that |
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-d shows. The effect of -d is now the same as -b with -i (and similarly, /D |
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is the same as /B/I). |
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23. A new optimization is now able automatically to treat some sequences such |
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as a*b as a*+b. More specifically, if something simple (such as a character |
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or a simple class like \d) has an unlimited quantifier, and is followed by |
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something that cannot possibly match the quantified thing, the quantifier |
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is automatically "possessified". |
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24. A recursive reference to a subpattern whose number was greater than 39 |
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went wrong under certain circumstances in UTF-8 mode. This bug could also |
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have affected the operation of pcre_study(). |
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25. Realized that a little bit of performance could be had by replacing |
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(c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters. |
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26. Timing data from pcretest is now shown to 4 decimal places instead of 3. |
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27. Possessive quantifiers such as a++ were previously implemented by turning |
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them into atomic groups such as ($>a+). Now they have their own opcodes, |
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which improves performance. This includes the automatically created ones |
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from 23 above. |
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28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a |
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lookahead was broken if it was not anchored. PCRE was mistakenly expecting |
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the first matched character to be a colon. This applied both to named and |
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numbered groups. |
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29. The ucpinternal.h header file was missing its idempotency #ifdef. |
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30. I was sent a "project" file called libpcre.a.dev which I understand makes |
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building PCRE on Windows easier, so I have included it in the distribution. |
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31. There is now a check in pcretest against a ridiculously large number being |
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returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G |
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loop, the loop is abandoned. |
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32. Forward references to subpatterns in conditions such as (?(2)...) where |
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subpattern 2 is defined later cause pcre_compile() to search forwards in |
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the pattern for the relevant set of parentheses. This search went wrong |
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when there were unescaped parentheses in a character class, parentheses |
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escaped with \Q...\E, or parentheses in a #-comment in /x mode. |
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33. "Subroutine" calls and backreferences were previously restricted to |
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referencing subpatterns earlier in the regex. This restriction has now |
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been removed. |
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34. Added a number of extra features that are going to be in Perl 5.10. On the |
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whole, these are just syntactic alternatives for features that PCRE had |
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previously implemented using the Python syntax or my own invention. The |
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other formats are all retained for compatibility. |
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(a) Named groups can now be defined as (?<name>...) or (?'name'...) as well |
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as (?P<name>...). The new forms, as well as being in Perl 5.10, are |
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also .NET compatible. |
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(b) A recursion or subroutine call to a named group can now be defined as |
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(?&name) as well as (?P>name). |
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(c) A backreference to a named group can now be defined as \k<name> or |
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\k'name' as well as (?P=name). The new forms, as well as being in Perl |
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5.10, are also .NET compatible. |
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(d) A conditional reference to a named group can now use the syntax |
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(?(<name>) or (?('name') as well as (?(name). |
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(e) A "conditional group" of the form (?(DEFINE)...) can be used to define |
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groups (named and numbered) that are never evaluated inline, but can be |
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called as "subroutines" from elsewhere. In effect, the DEFINE condition |
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is always false. There may be only one alternative in such a group. |
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(f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well |
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as the simple (?(R). The condition is true only if the most recent |
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recursion is that of the given number or name. It does not search out |
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through the entire recursion stack. |
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(g) The escape \gN or \g{N} has been added, where N is a positive or |
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negative number, specifying an absolute or relative reference. |
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35. Tidied to get rid of some further signed/unsigned compiler warnings and |
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some "unreachable code" warnings. |
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36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other |
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things, this adds five new scripts. |
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37. Perl ignores orphaned \E escapes completely. PCRE now does the same. |
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There were also incompatibilities regarding the handling of \Q..\E inside |
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character classes, for example with patterns like [\Qa\E-\Qz\E] where the |
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hyphen was adjacent to \Q or \E. I hope I've cleared all this up now. |
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38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group |
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matches an empty string, and forcibly breaks the loop. There were bugs in |
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this code in non-simple cases. For a pattern such as ^(a()*)* matched |
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against aaaa the result was just "a" rather than "aaaa", for example. Two |
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separate and independent bugs (that affected different cases) have been |
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fixed. |
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39. Refactored the code to abolish the use of different opcodes for small |
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capturing bracket numbers. This is a tidy that I avoided doing when I |
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removed the limit on the number of capturing brackets for 3.5 back in 2001. |
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The new approach is not only tidier, it makes it possible to reduce the |
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memory needed to fix the previous bug (38). |
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40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline |
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sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when |
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processing dot, circumflex, or dollar metacharacters, or #-comments in /x |
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mode. |
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41. Add \R to match any Unicode newline sequence, as suggested in the Unicode |
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report. |
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42. Applied patch, originally from Ari Pollak, modified by Google, to allow |
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copy construction and assignment in the C++ wrapper. |
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43. Updated pcregrep to support "--newline=any". In the process, I fixed a |
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couple of bugs that could have given wrong results in the "--newline=crlf" |
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case. |
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44. Added a number of casts and did some reorganization of signed/unsigned int |
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variables following suggestions from Dair Grant. Also renamed the variable |
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"this" as "item" because it is a C++ keyword. |
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45. Arranged for dftables to add |
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#include "pcre_internal.h" |
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to pcre_chartables.c because without it, gcc 4.x may remove the array |
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definition from the final binary if PCRE is built into a static library and |
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dead code stripping is activated. |
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46. For an unanchored pattern, if a match attempt fails at the start of a |
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newline sequence, and the newline setting is CRLF or ANY, and the next two |
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characters are CRLF, advance by two characters instead of one. |
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Version 6.7 04-Jul-06 |
Version 6.7 04-Jul-06 |
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--------------------- |
--------------------- |
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|
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