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revision 372 by ph10, Tue Aug 26 11:49:38 2008 UTC revision 539 by ph10, Sun Jun 13 21:35:04 2010 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.
106    
107  . Run ./autogen.sh to ensure everything is up-to-date.  . Run ./autogen.sh to ensure everything is up-to-date.
108    
109  . Compile and test with many different config options, and combinations of  . Compile and test with many different config options, and combinations of
110    options. The maint/ManyConfigTests script now encapsulates this testing.    options. The maint/ManyConfigTests script now encapsulates this testing.
111    
112  . 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, and 11. The first two can
113    the PCRE test output, apart from the version identification at the top. The    be run with Perl 5.8 or >= 5.10; the last two require Perl >= 5.10. The
114    other tests are not Perl-compatible (they use various special PCRE options).    output should match the PCRE test output, apart from the version
115      identification at the start of each test. The other tests are not
116      Perl-compatible (they use various PCRE-specific features or options).
117    
118  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest
119    valgrind", though that takes quite a long time.    valgrind", though that takes quite a long time.
# Line 116  distribution for a new release. Line 136  distribution for a new release.
136    used" warnings for the modules in which there is no call to memmove(). These    used" warnings for the modules in which there is no call to memmove(). These
137    can be ignored.    can be ignored.
138    
139  . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,  . Documentation: check AUTHORS, COPYING, ChangeLog (check version and date),
140    LICENCE, NEWS (check date), NON-UNIX-USE, and README. Many of these won't    INSTALL, LICENCE, NEWS (check version and date), NON-UNIX-USE, and README.
141    need changing, but over the long term things do change.    Many of these won't need changing, but over the long term things do change.
142    
143  . Man pages: Check all man pages for \ not followed by e or f or " because  . Man pages: Check all man pages for \ not followed by e or f or " because
144    that indicates a markup error.    that indicates a markup error. However, there is one exception: pcredemo.3,
145      which is created from the pcredemo.c program. It contains three instances
146      of \\n.
147    
148  . When the release is built, test it on a number of different operating  . When the release is built, test it on a number of different operating
149    systems if possible, and using different compilers as well. For example,    systems if possible, and using different compilers as well. For example,
# Line 131  distribution for a new release. Line 153  distribution for a new release.
153    
154    
155  Making a PCRE release  Making a PCRE release
156  ---------------------  =====================
157    
158  Run PrepareRelease and commit the files that it changes (by removing trailing  Run PrepareRelease and commit the files that it changes (by removing trailing
159  spaces). Then run "make distcheck" to create the tarballs and the zipball.  spaces). Then run "make distcheck" to create the tarballs and the zipball.
160  Double-check with "svn status", then create an SVN tagged copy:  Double-check with "svn status", then create an SVN tagged copy:
161    
162    svn copy svn://vcs.exim.org/pcre/code/trunk \    svn copy svn://vcs.exim.org/pcre/code/trunk \
163             svn://vcs.exim.org/pcre/code/tags/pcre-7.x             svn://vcs.exim.org/pcre/code/tags/pcre-8.xx
164    
165  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
166  webmaster@pcre.org and the mailing list.  webmaster@pcre.org and the mailing list. Also, update the list of version
167    numbers in Bugzilla (edit products).
168    
169    
170  Future ideas (wish list)  Future ideas (wish list)
171  ------------------------  ========================
172    
173  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
174  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 189  others are relatively new.
189      to have little effect, and maybe makes things worse.      to have little effect, and maybe makes things worse.
190    
191    * "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
192      over the existing "required byte" (reqbyte) feature that just saves one      over the existing "required byte" (reqbyte) feature that just remembers one
193      byte.      byte.
194    
195    * These probably need to go in study():    * These probably need to go in pcre_study():
196    
197      o Remember an initial string rather than just 1 char?      o Remember an initial string rather than just 1 char?
198    
199      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
200        earlier one if common to all alternatives.        earlier one if common to all alternatives.
201    
     o Minimum length of subject needed.  
   
202      o Friedl contains other ideas.      o Friedl contains other ideas.
203    
204      * pcre_study() does not set initial byte flags for Unicode property types
205        such as \p; I don't know how much benefit there would be for, for example,
206        setting the bits for 0-9 and all bytes >= xC0 when a pattern starts with
207        \p{N}.
208    
209      * There is scope for more "auto-possessifying" in connection with \p and \P.
210    
211  . 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-
212    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
213    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 218  others are relatively new.
218    
219  . Unicode  . Unicode
220    
   * Note that in Perl, \s matches \pZ and similarly for \d, \w and the POSIX  
     character classes. For the moment, I've chosen not to support this for  
     backward compatibility, for speed, and because it would be messy to  
     implement.  
   
221    * 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
222      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
223      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
# Line 213  others are relatively new. Line 236  others are relatively new.
236    
237    * 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
238      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.
239      If this is done, a suitable option for pcregrep is also required.      If it is done, a suitable option for pcregrep is also required.
240    
241  . 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.
242    This probably affects quite a few places in the code.    This affects quite a few places in the code and is not trivial.
243    
244  . Catch SIGSEGV for stack overflows?  . Catch SIGSEGV for stack overflows?
245    
# Line 231  others are relatively new. Line 254  others are relatively new.
254    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)
255    support --outputfile=name.    support --outputfile=name.
256    
257  . 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.
258    
259  . 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
260    needed to retain backward compatibility.    needed to retain backward compatibility.
# Line 256  others are relatively new. Line 279  others are relatively new.
279    
280  . Someone suggested --disable-callout to save code space when callouts are  . Someone suggested --disable-callout to save code space when callouts are
281    never wanted. This seems rather marginal.    never wanted. This seems rather marginal.
282    
283  . 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
284    Python, etc?    Python, etc?
285    
286  . 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
287    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
288    substring exceeds N. This could apply to both match functions. The value    substring exceeds N. This could apply to both match functions. The value
289    could be a new field in the extra block.    could be a new field in the extra block.
290    
291  . Callouts with arguments: (?Cn:ARG) for instance.  . Callouts with arguments: (?Cn:ARG) for instance.
292    
293  . 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
294    memory allocation so that it is more flexible in threaded environments.    memory allocation so that it is more flexible in threaded environments. This
295      was promised a long time ago, and never appeared...
296    
297    . Write a function that generates random matching strings for a compiled regex.
298    
299    . Write a wrapper to maintain a structure with specified runtime parameters,
300      such as recurse limit, and pass these to PCRE each time it is called. Also
301      maybe malloc and free. A user sent a prototype.
302    
303    . Pcregrep: an option to specify the output line separator, either as a string
304      or select from a fixed list. This is not dead easy, because at the moment it
305      outputs whatever is in the input file.
306    
307    . Improve the code for duplicate checking in pcre_dfa_exec(). An incomplete,
308      non-thread-safe patch showed that this can help performance for patterns
309      where there are many alternatives. However, a simple thread-safe
310      implementation that I tried made things worse in many simple cases, so this
311      is not an obviously good thing.
312    
313    . Make the longest lookbehind available via pcre_fullinfo(). This is not
314      straightforward because lookbehinds can be nested inside lookbehinds. This
315      case will have to be identified, and the amounts added. This should then give
316      the maximum possible lookbehind length. The reason for wanting this is to
317      help when implementing multi-segment matching using pcre_exec() with partial
318      matching and overlapping segments.
319    
320    . PCRE cannot at present distinguish between subpatterns with different names,
321      but the same number (created by the use of ?|). In order to do so, a way of
322      remembering *which* subpattern numbered n matched is needed. Bugzilla #760.
323      Now that (*MARK) has been implemented, it can perhaps be used as a way round
324      this problem.
325    
326    . Instead of having #ifdef HAVE_CONFIG_H in each module, put #include
327      "something" and the the #ifdef appears only in one place, in "something".
328    
329  Philip Hazel  Philip Hazel
330  Email local part: ph10  Email local part: ph10
331  Email domain: cam.ac.uk  Email domain: cam.ac.uk
332  Last updated: 26 August 2008  Last updated: 03 June 2010

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