/[pcre]/code/trunk/maint/README
ViewVC logotype

Diff of /code/trunk/maint/README

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 155 by ph10, Tue Apr 24 13:36:11 2007 UTC revision 654 by ph10, Tue Aug 2 11:00:40 2011 UTC
# Line 1  Line 1 
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
6  part of the PCRE distribution tarballs. This document describes these files and  part of the PCRE distribution tarballs. This document describes these files and
7  also contains some notes for maintainers. Its contents are:  also contains some notes for maintainers. Its contents are:
8    
9    Files in the maint directory    Files in the maint directory
10    Updating to a new Unicode release    Updating to a new Unicode release
11    Preparing for a PCRE release    Preparing for a PCRE release
12    Making a PCRE release    Making a PCRE release
13    Long-term ideas (wish list)    Long-term ideas (wish list)
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 ----------------
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 ----------------
25    
26    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
28                     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  Unicode.tables   The files in this directory, Scripts.txt and UnicodeData.txt,  MultiStage2.py   A Python script that generates the file pcre_ucd.c from three
34                   were downloaded from the Unicode web site. They contain                   Unicode data tables, which are themselves downloaded from the
35                   information about Unicode characters and scripts.                   Unicode web site. Run this script in the "maint" directory.
36                     The generated file contains the tables for a 2-stage lookup
37  ucptest.c        A short C program for testing the Unicode property functions                   of Unicode properties.
38                   in pcre_ucp_searchfuncs.c, mainly useful after rebuilding the  
39                   Unicode property table. Compile and run this in the "maint"  pcre_chartables.c.non-standard
40                   directory.                   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,
48                     Scripts.txt and UnicodeData.txt, were downloaded from the
49                     Unicode web site. They contain information about Unicode
50                     characters and scripts.
51    
52    ucptest.c        A short C program for testing the Unicode property macros
53                     that do lookups in the pcre_ucd.c data, mainly useful after
54                     rebuilding the Unicode property table. Compile and run this in
55                     the "maint" directory (see comments at its head).
56    
57  ucptestdata      A directory containing two files, testinput1 and testoutput1,  ucptestdata      A directory containing two files, testinput1 and testoutput1,
58                   to use in conjunction with the ucptest program.                   to use in conjunction with the ucptest program.
59    
60  utf8.c           A short, freestanding C program for converting a Unicode code  utf8.c           A short, freestanding C program for converting a Unicode code
61                   point into a sequence of bytes in the UTF-8 encoding, and vice                   point into a sequence of bytes in the UTF-8 encoding, and vice
62                   versa. If its argument is a hex number such as 0x1234, it                   versa. If its argument is a hex number such as 0x1234, it
# Line 43  utf8.c           A short, freestanding C Line 64  utf8.c           A short, freestanding C
64                   is sequence of concatenated UTF-8 bytes (e.g. e188b4) it                   is sequence of concatenated UTF-8 bytes (e.g. e188b4) it
65                   treats them as a UTF-8 character and outputs the equivalent                   treats them as a UTF-8 character and outputs the equivalent
66                   code point in hex.                   code point in hex.
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
73    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
75    GenerateUtt.py scripts must be edited to add the new names. Then MultiStage2.py
76    can be run to generate a new version of pcre_ucd.c, and GenerateUtt.py can be
77    run to generate the tricky tables for inclusion in pcre_tables.c.
78    
79    If MultiStage2.py gives the error "ValueError: list.index(x): x not in list",
80    the cause is usually a missing (or misspelt) name in the list of scripts. I
81    couldn't find a straightforward list of scripts on the Unicode site, but
82    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  When there is a new release of Unicode, the files in Unicode.tables must be  Note also that both the pcresyntax.3 and pcrepattern.3 man pages contain lists
93  refreshed from the web site, and the Buildupctable script can then be run to  of Unicode script names.
 generate a new version of ucptable.h. The ucptest program can be used to check  
 that the resulting table works properly, using the data files in ucptestdata to  
 check a number of test characters.  
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
105      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    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 \
152               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
164  very sensible; some are rather wacky. Some have been on this list for years;  very sensible; some are rather wacky. Some have been on this list for years;
165  others are relatively new.  others are relatively new.
166    
167  . Optimization  . Optimization
168    
169    There are always ideas for new optimizations so as to speed up pattern    There are always ideas for new optimizations so as to speed up pattern
170    matching. Most of them try to save work by recognizing a non-match without    matching. Most of them try to save work by recognizing a non-match without
171    having to scan all the possibilities. These are some that I've recorded:    having to scan all the possibilities. These are some that I've recorded:
172    
173    * /((A{0,5}){0,5}){0,5}(something complex)/ on a non-matching string is very    * /((A{0,5}){0,5}){0,5}(something complex)/ on a non-matching string is very
174      slow, though Perl is fast. Can we speed up somehow? Convert to {0,125}?      slow, though Perl is fast. Can we speed up somehow? Convert to {0,125}?
175      OTOH, this is pathological - the user could easily fix it.      OTOH, this is pathological - the user could easily fix it.
176    
177    * Turn ={4} into ==== ? (for speed). I once did an experiment, and it seems    * Turn ={4} into ==== ? (for speed). I once did an experiment, and it seems
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
203    leaves $2 set. In Perl, it's unset. Changing this in PCRE will be very hard    leaves $2 set. In Perl, it's unset. Changing this in PCRE will be very hard
204    because I think it needs much more state to be remembered.    because I think it needs much more state to be remembered.
205    
206  . Perl 6 will be a revolution. Is it a revolution too far for PCRE?  . Perl 6 will be a revolution. Is it a revolution too far for PCRE?
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.
226    * 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.  
   
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    
229  . Line endings:  . Line endings:
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?
   
 . "Cut" as described in Jeffrey Friedl's book, p364: \v and \V. The definitions  
   aren't yet clear enough for me. \v flushes saved states so that no  
   backtracking to anything earlier can happen; \V says "no more bumpalong", but  
   does it fail the current match? As described in the book, these aren't really  
   "cut" as in Prolog, are they? NOTE: (a) PCRE once had "cut", but it was  
   removed when atomic groups were introduced. (b) Perl 5.10 has some (*PRUNE)  
   features -- see below.  
239    
240  . A feature to suspend a match via a callout was once requested.  . A feature to suspend a match via a callout was once requested.
241    
242  . Option to convert results into character offsets and character lengths.  . Option to convert results into character offsets and character lengths.
243    
244  . Option for pcregrep to scan only the start of a file. I am not keen - this is  . Option for pcregrep to scan only the start of a file. I am not keen - this is
245    the job of "head".    the job of "head".
246    
247  . A (non-Unix) user wanted pcregrep options to (a) list a file name just once,  . A (non-Unix) user wanted pcregrep options to (a) list a file name just once,
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.
   
 . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 7.  
250    
251  . Add a user pointer to pcre_malloc/free functions -- some option would be  . 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
254    needed to retain backward compatibility.    needed to retain backward compatibility.
255    
256  . Define a union for the results from pcre_fullinfo().  . Define a union for the results from pcre_fullinfo().
257    
258  . Provide a "random access to the subject" facility so that the way in which it  . Provide a "random access to the subject" facility so that the way in which it
259    is stored is independent of PCRE. For efficiency, it probably isn't possible    is stored is independent of PCRE. For efficiency, it probably isn't possible
260    to switch this dynamically. It would have to be specified when PCRE was    to switch this dynamically. It would have to be specified when PCRE was
261    compiled. PCRE would then call a function every time it wanted a character.    compiled. PCRE would then call a function every time it wanted a character.
262    
 . There are new (*PRUNE) facilities in Perl 5.10, some of which it might be  
   relatively easy to implement.  
   
 . Also in Perl 5.10 are relative subroutine references (?&-1) and (?&+1) which  
   I didn't know about when I added some 5.10 features for PCRE 7.0. What about  
   (?(-1)... as a condition? That's an obvious extension, even if Perl 5.10  
   doesn't have it.  
   
263  . Wild thought: the ability to compile from PCRE's internal byte code to a real  . Wild thought: the ability to compile from PCRE's internal byte code to a real
264    FSM and a very fast (third) matcher to process the result. There would be    FSM and a very fast (third) matcher to process the result. There would be
265    even more restrictions than for pcre_dfa_exec(), however. This is not easy.    even more restrictions than for pcre_dfa_exec(), however. This is not easy.
266    
267  . Should pcretest have some private locale data, to avoid relying on the  . Should pcretest have some private locale data, to avoid relying on the
268    available locales for the test data, since different OS have different ideas?    available locales for the test data, since different OS have different ideas?
269    This won't be as thorough a test, but perhaps that doesn't really matter.    This won't be as thorough a test, but perhaps that doesn't really matter.
270    
271  . pcregrep: add -rs for a sorted recurse? Having to store file names and sort  . pcregrep: add -rs for a sorted recurse? Having to store file names and sort
272    them will of course slow it down.    them will of course slow it down.
273    
274  . Re-arrange test 2: take out the link-size dependent stuff for a separate test  . Someone suggested --disable-callout to save code space when callouts are
275    that is run only when the link size *is* 2; leave in some non-numbered    never wanted. This seems rather marginal.
276    debugging tests using the new /Z feature.  
277    . Check names that consist entirely of digits: PCRE allows, but do Perl and
278  . Stan Switzer's goto replacement for longjmp, which is apparently very slow on    Python, etc?
279    OS-X. This is used when stack recursion is disabled. It would be worth doing  
280    some timing tests on other OS.  . 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
282  . Someone suggested --disable-callout to save code space when callouts are    substring exceeds N. This could apply to both match functions. The value
283    never wanted. This seems rather marginal.    could be a new field in the extra block.
284    
285  . Work needs doing so that the pcregrep tests work better with different  . Callouts with arguments: (?Cn:ARG) for instance.
286    linebreak settings. Currently, some tests don't work when the input files  
287    do not have \n line endings.  . 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. This
289  . If the fr_FR locale isn't available for testing, try "french" instead,    was promised a long time ago, and never appeared...
290    because this may be available on Windows. It means modifying the test data,  
291    however.  . 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: 24 April 2007  Last updated: 02 August 2011

Legend:
Removed from v.155  
changed lines
  Added in v.654

  ViewVC Help
Powered by ViewVC 1.1.5