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revision 372 by ph10, Tue Aug 26 11:49:38 2008 UTC revision 654 by ph10, Tue Aug 2 11:00:40 2011 UTC
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1  MAINTENANCE README FOR PCRE  MAINTENANCE README FOR PCRE
2  ---------------------------  ===========================
3    
4  The files in the "maint" directory of the PCRE source contain data, scripts,  The files in the "maint" directory of the PCRE source contain data, scripts,
5  and programs that are used for the maintenance of PCRE, but which do not form  and programs that are used for the maintenance of PCRE, but which do not form
# Line 14  also contains some notes for maintainers Line 14  also contains some notes for maintainers
14    
15    
16  Files in the maint directory  Files in the maint directory
17  ----------------------------  ============================
18    
19  ----------------- This file is now OBSOLETE and no longer used ----------------  ---------------- This file is now OBSOLETE and no longer used ----------------
20  Builducptable    A Perl script that creates the contents of the ucptable.h file  Builducptable    A Perl script that creates the contents of the ucptable.h file
21                   from two Unicode data files, which themselves are downloaded                   from two Unicode data files, which themselves are downloaded
22                   from the Unicode web site. Run this script in the "maint"                   from the Unicode web site. Run this script in the "maint"
23                   directory.                   directory.
24  ----------------- This file is now OBSOLETE and no longer used ----------------  ---------------- This file is now OBSOLETE and no longer used ----------------
25    
26  GenerateUtt.py   A Python script to generate part of the pcre_tables.c file  GenerateUtt.py   A Python script to generate part of the pcre_tables.c file
27                   that contains Unicode script names in a long string with                   that contains Unicode script names in a long string with
28                   offsets, which is tedious to maintain by hand.                   offsets, which is tedious to maintain by hand.
29    
30  ManyConfigTests  A shell script that runs "configure, make, test" a number of  ManyConfigTests  A shell script that runs "configure, make, test" a number of
31                   times with different configuration settings.                   times with different configuration settings.
32    
33  MultiStage2.py   A Python script that generates the file pcre_ucd.c from three  MultiStage2.py   A Python script that generates the file pcre_ucd.c from three
34                   Unicode data tables, which are themselves downloaded from the                   Unicode data tables, which are themselves downloaded from the
35                   Unicode web site. Run this script in the "maint" directory.                   Unicode web site. Run this script in the "maint" directory.
36                   The generated file contains the tables for a 2-stage lookup                   The generated file contains the tables for a 2-stage lookup
37                   of Unicode properties.                   of Unicode properties.
38    
39    pcre_chartables.c.non-standard
40                     This is a set of character tables that came from a Windows
41                     system. It has characters greater than 128 that are set as
42                     spaces, amongst other things. I kept it so that it can be
43                     used for testing from time to time.
44    
45    README           This file.
46    
47  Unicode.tables   The files in this directory, DerivedGeneralCategory.txt,  Unicode.tables   The files in this directory, DerivedGeneralCategory.txt,
48                   Scripts.txt and UnicodeData.txt, were downloaded from the                   Scripts.txt and UnicodeData.txt, were downloaded from the
49                   Unicode web site. They contain information about Unicode                   Unicode web site. They contain information about Unicode
50                   characters and scripts.                   characters and scripts.
# Line 59  utf8.c           A short, freestanding C Line 67  utf8.c           A short, freestanding C
67    
68    
69  Updating to a new Unicode release  Updating to a new Unicode release
70  ---------------------------------  =================================
71    
72  When there is a new release of Unicode, the files in Unicode.tables must be  When there is a new release of Unicode, the files in Unicode.tables must be
73  refreshed from the web site. If the new version of Unicode adds new character  refreshed from the web site. If the new version of Unicode adds new character
74  scripts, the source file ucp.h and both the MultiStage2.py and the  scripts, the source file ucp.h and both the MultiStage2.py and the
75  GenerateUtt.py scripts must be edited to add the new names. Then the  GenerateUtt.py scripts must be edited to add the new names. Then MultiStage2.py
76  MultiStage2.py script can then be run to generate a new version of pcre_ucd.c  can be run to generate a new version of pcre_ucd.c, and GenerateUtt.py can be
77  and the GenerateUtt.py can be run to generate the tricky tables for inclusion  run to generate the tricky tables for inclusion in pcre_tables.c.
78  in pcre_tables.c.  
79    If MultiStage2.py gives the error "ValueError: list.index(x): x not in list",
80  The ucptest program can then be compiled and used to check that the new tables  the cause is usually a missing (or misspelt) name in the list of scripts. I
81  in pcre_ucd.c work properly, using the data files in ucptestdata to check a  couldn't find a straightforward list of scripts on the Unicode site, but
82  number of test characters.  there's a useful Wikipedia page that list them, and notes the Unicode version
83    in which they were introduced:
84    
85    http://en.wikipedia.org/wiki/Unicode_scripts#Table_of_Unicode_scripts
86    
87    The ucptest program can be compiled and used to check that the new tables in
88    pcre_ucd.c work properly, using the data files in ucptestdata to check a number
89    of test characters. The source file ucptest.c must be updated whenever new
90    Unicode script names are added.
91    
92    Note also that both the pcresyntax.3 and pcrepattern.3 man pages contain lists
93    of Unicode script names.
94    
95    
96  Preparing for a PCRE release  Preparing for a PCRE release
97  ----------------------------  ============================
98    
99  This section contains a checklist of things that I consult before building a  This section contains a checklist of things that I consult before building a
100  distribution for a new release.  distribution for a new release.
101    
102  . Ensure that the version number and version date are correct in configure.ac,  . Ensure that the version number and version date are correct in configure.ac.
103    ChangeLog, and NEWS.  
   
104  . If new build options have been added, ensure that they are added to the CMake  . If new build options have been added, ensure that they are added to the CMake
105    files as well as to the autoconf files.    files as well as to the autoconf files. The relevant files are CMakeLists.txt
106      and config-cmake.h.in. After making a release tarball, test it out with CMake
107      if there have been changes here.
108    
109  . Run ./autogen.sh to ensure everything is up-to-date.  . Run ./autogen.sh to ensure everything is up-to-date.
110    
111  . Compile and test with many different config options, and combinations of  . Compile and test with many different config options, and combinations of
112    options. The maint/ManyConfigTests script now encapsulates this testing.    options. The maint/ManyConfigTests script now encapsulates this testing.
113    
114  . Run perltest.pl on the test data for tests 1 and 4. The output should match  . Run perltest.pl on the test data for tests 1, 4, 6, 11, and 12. The output
115    the PCRE test output, apart from the version identification at the top. The    should match the PCRE test output, apart from the version identification at
116    other tests are not Perl-compatible (they use various special PCRE options).    the start of each test. The other tests are not Perl-compatible (they use
117      various PCRE-specific features or options).
118    
119  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest
120    valgrind", though that takes quite a long time.    valgrind", though that takes quite a long time.
121    
122  . It may also useful to test with Electric Fence, though the fact that it  . It is possible to test with the emulated memmove() function by undefining
123    grumbles for missing free() calls can be a nuisance. (A missing free() in    HAVE_MEMMOVE and HAVE_BCOPY in config.h, though I do not do this often. You
124    pcretest is hardly a big problem.) To build with EF, use:    may see a number of "pcre_memmove defined but not used" warnings for the
125      modules in which there is no call to memmove(). These can be ignored.
126      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.  
127    . Documentation: check AUTHORS, COPYING, ChangeLog (check version and date),
128    Then all normal runs use it to check for buffer overflow. Also run everything    INSTALL, LICENCE, NEWS (check version and date), NON-UNIX-USE, and README.
129    with:    Many of these won't need changing, but over the long term things do change.
130    
131      EF_PROTECT_BELOW=1 <whatever>  . I used to test new releases myself on a number of different operating
132      systems, using different compilers as well. For example, on Solaris it is
133    because there have been problems with lookbehinds that looked too far.    helpful to test using Sun's cc compiler as a change from gcc. Adding
134      -xarch=v9 to the cc options does a 64-bit test, but it also needs -S 64 for
135  . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and    pcretest to increase the stack size for test 2. Since I retired I can no
136    HAVE_BCOPY in config.h. You may see a number of "pcre_memmove defined but not    longer do this, but instead I rely on putting out release candidates for
137    used" warnings for the modules in which there is no call to memmove(). These    folks on the pcre-dev list to test.
   can be ignored.  
   
 . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,  
   LICENCE, NEWS (check date), NON-UNIX-USE, and README. Many of these won't  
   need changing, but over the long term things do change.  
   
 . Man pages: Check all man pages for \ not followed by e or f or " because  
   that indicates a markup error.  
   
 . When the release is built, test it on a number of different operating  
   systems if possible, and using different compilers as well. For example,  
   on Solaris it is helpful to test using Sun's cc compiler as a change from  
   gcc. Adding -xarch=v9 to the cc options does a 64-bit test, but it also  
   needs -S 64 for pcretest to increase the stack size for test 2.  
138    
139    
140  Making a PCRE release  Making a PCRE release
141  ---------------------  =====================
142    
143  Run PrepareRelease and commit the files that it changes (by removing trailing  Run PrepareRelease and commit the files that it changes (by removing trailing
144  spaces). Then run "make distcheck" to create the tarballs and the zipball.  spaces). The first thing this script does is to run CheckMan on the man pages;
145  Double-check with "svn status", then create an SVN tagged copy:  if it finds any markup errors, it reports them and then aborts.
146    
147    Once PrepareRelease has run clean, run "make distcheck" to create the tarballs
148    and the zipball. Double-check with "svn status", then create an SVN tagged
149    copy:
150    
151    svn copy svn://vcs.exim.org/pcre/code/trunk \    svn copy svn://vcs.exim.org/pcre/code/trunk \
152             svn://vcs.exim.org/pcre/code/tags/pcre-7.x             svn://vcs.exim.org/pcre/code/tags/pcre-8.xx
153    
154  Don't forget to update Freshmeat when the new release is out, and to tell  Don't forget to update Freshmeat when the new release is out, and to tell
155  webmaster@pcre.org and the mailing list.  webmaster@pcre.org and the mailing list. Also, update the list of version
156    numbers in Bugzilla (edit products).
157    
158    
159  Future ideas (wish list)  Future ideas (wish list)
160  ------------------------  ========================
161    
162  This section records a list of ideas so that they do not get forgotten. They  This section records a list of ideas so that they do not get forgotten. They
163  vary enormously in their usefulness and potential for implementation. Some are  vary enormously in their usefulness and potential for implementation. Some are
# Line 166  others are relatively new. Line 178  others are relatively new.
178      to have little effect, and maybe makes things worse.      to have little effect, and maybe makes things worse.
179    
180    * "Ends with literal string" - note that a single character doesn't gain much    * "Ends with literal string" - note that a single character doesn't gain much
181      over the existing "required byte" (reqbyte) feature that just saves one      over the existing "required byte" (reqbyte) feature that just remembers one
182      byte.      byte.
183    
184    * These probably need to go in study():    * These probably need to go in pcre_study():
185    
186      o Remember an initial string rather than just 1 char?      o Remember an initial string rather than just 1 char?
187    
188      o A required byte from alternatives - not just the last char, but an      o A required byte from alternatives - not just the last char, but an
189        earlier one if common to all alternatives.        earlier one if common to all alternatives.
190    
     o Minimum length of subject needed.  
   
191      o Friedl contains other ideas.      o Friedl contains other ideas.
192    
193      * pcre_study() does not set initial byte flags for Unicode property types
194        such as \p; I don't know how much benefit there would be for, for example,
195        setting the bits for 0-9 and all bytes >= xC0 when a pattern starts with
196        \p{N}.
197    
198      * There is scope for more "auto-possessifying" in connection with \p and \P.
199    
200  . If Perl gets to a consistent state over the settings of capturing sub-  . If Perl gets to a consistent state over the settings of capturing sub-
201    patterns inside repeats, see if we can match it. One example of the    patterns inside repeats, see if we can match it. One example of the
202    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE
# Line 190  others are relatively new. Line 207  others are relatively new.
207    
208  . Unicode  . Unicode
209    
210    * Note that in Perl, \s matches \pZ and similarly for \d, \w and the POSIX    * There has been a request for direct support of 16-bit characters and
211      character classes. For the moment, I've chosen not to support this for      UTF-16 (Bugzilla #1049). However, since Unicode is moving beyond purely
212      backward compatibility, for speed, and because it would be messy to      16-bit characters, is this worth it at all? One possible way of handling
213      implement.      16-bit characters would be to "load" them in the same way that UTF-8
214        characters are loaded. Another possibility is to provide a set of
215        translation functions, and build an index during translation so that the
216        returned offsets can automatically be translated (using the index) after a
217        match.
218    
219    * A different approach to Unicode might be to use a typedef to do everything    * A different approach to Unicode might be to use a typedef to do everything
220      in unsigned shorts instead of unsigned chars. Actually, we'd have to have a      in unsigned shorts instead of unsigned chars. Actually, we'd have to have a
221      new typedef to distinguish data from bits of compiled pattern that are in      new typedef to distinguish data from bits of compiled pattern that are in
222      bytes, I think. There would need to be conversion functions in and out. I      bytes, I think. There would need to be conversion functions in and out. I
223      don't think this is particularly trivial - and anyway, Unicode now has      don't think this is particularly trivial - and anyway, Unicode now has
224      characters that need more than 16 bits, so is this at all sensible?      characters that need more than 16 bits, so is this at all sensible? I
225        suspect not.
   * There has been a request for direct support of 16-bit characters and  
     UTF-16. However, since Unicode is moving beyond purely 16-bit characters,  
     is this worth it at all? One possible way of handling 16-bit characters  
     would be to "load" them in the same way that UTF-8 characters are loaded.  
226    
227  . Allow errorptr and erroroffset to be NULL. I don't like this idea.  . Allow errorptr and erroroffset to be NULL. I don't like this idea.
228    
# Line 213  others are relatively new. Line 230  others are relatively new.
230    
231    * Option to use NUL as a line terminator in subject strings. This could now    * Option to use NUL as a line terminator in subject strings. This could now
232      be done relatively easily since the extension to support LF, CR, and CRLF.      be done relatively easily since the extension to support LF, CR, and CRLF.
233      If this is done, a suitable option for pcregrep is also required.      If it is done, a suitable option for pcregrep is also required.
234    
235  . Option to provide the pattern with a length instead of with a NUL terminator.  . Option to provide the pattern with a length instead of with a NUL terminator.
236    This probably affects quite a few places in the code.    This affects quite a few places in the code and is not trivial.
237    
238  . Catch SIGSEGV for stack overflows?  . Catch SIGSEGV for stack overflows?
239    
# Line 231  others are relatively new. Line 248  others are relatively new.
248    preceded by a blank line, instead of adding it to every matched line, and (b)    preceded by a blank line, instead of adding it to every matched line, and (b)
249    support --outputfile=name.    support --outputfile=name.
250    
251  . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 7.  . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 8.
252    
253  . Add a user pointer to pcre_malloc/free functions -- some option would be  . Add a user pointer to pcre_malloc/free functions -- some option would be
254    needed to retain backward compatibility.    needed to retain backward compatibility.
# Line 256  others are relatively new. Line 273  others are relatively new.
273    
274  . Someone suggested --disable-callout to save code space when callouts are  . Someone suggested --disable-callout to save code space when callouts are
275    never wanted. This seems rather marginal.    never wanted. This seems rather marginal.
276    
277  . Check names that consist entirely of digits: PCRE allows, but do Perl and  . Check names that consist entirely of digits: PCRE allows, but do Perl and
278    Python, etc?    Python, etc?
279    
280  . A user suggested a parameter to limit the length of string matched, for  . A user suggested a parameter to limit the length of string matched, for
281    example if the parameter is N, the current match should fail if the matched    example if the parameter is N, the current match should fail if the matched
282    substring exceeds N. This could apply to both match functions. The value    substring exceeds N. This could apply to both match functions. The value
283    could be a new field in the extra block.    could be a new field in the extra block.
284    
285  . Callouts with arguments: (?Cn:ARG) for instance.  . Callouts with arguments: (?Cn:ARG) for instance.
286    
287  . A user is going to supply a patch to generalize the API for user-specific  . A user is going to supply a patch to generalize the API for user-specific
288    memory allocation so that it is more flexible in threaded environments.    memory allocation so that it is more flexible in threaded environments. This
289      was promised a long time ago, and never appeared...
290    
291    . Write a function that generates random matching strings for a compiled regex.
292    
293    . Write a wrapper to maintain a structure with specified runtime parameters,
294      such as recurse limit, and pass these to PCRE each time it is called. Also
295      maybe malloc and free. A user sent a prototype.
296    
297    . Pcregrep: an option to specify the output line separator, either as a string
298      or select from a fixed list. This is not dead easy, because at the moment it
299      outputs whatever is in the input file.
300    
301    . Improve the code for duplicate checking in pcre_dfa_exec(). An incomplete,
302      non-thread-safe patch showed that this can help performance for patterns
303      where there are many alternatives. However, a simple thread-safe
304      implementation that I tried made things worse in many simple cases, so this
305      is not an obviously good thing.
306    
307    . Make the longest lookbehind available via pcre_fullinfo(). This is not
308      straightforward because lookbehinds can be nested inside lookbehinds. This
309      case will have to be identified, and the amounts added. This should then give
310      the maximum possible lookbehind length. The reason for wanting this is to
311      help when implementing multi-segment matching using pcre_exec() with partial
312      matching and overlapping segments.
313    
314    . PCRE cannot at present distinguish between subpatterns with different names,
315      but the same number (created by the use of ?|). In order to do so, a way of
316      remembering *which* subpattern numbered n matched is needed. Bugzilla #760.
317      Now that (*MARK) has been implemented, it can perhaps be used as a way round
318      this problem.
319    
320    . Instead of having #ifdef HAVE_CONFIG_H in each module, put #include
321      "something" and the the #ifdef appears only in one place, in "something".
322    
323  Philip Hazel  Philip Hazel
324  Email local part: ph10  Email local part: ph10
325  Email domain: cam.ac.uk  Email domain: cam.ac.uk
326  Last updated: 26 August 2008  Last updated: 02 August 2011

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