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

Contents of /code/trunk/maint/README

Parent Directory Parent Directory | Revision Log Revision Log


Revision 583 - (hide annotations) (download)
Tue Jan 11 16:49:55 2011 UTC (3 years, 7 months ago) by ph10
File size: 15019 byte(s)
Add script to check for man page markup typos. Fix some typos.

1 ph10 122 MAINTENANCE README FOR PCRE
2 ph10 507 ===========================
3 ph10 122
4 ph10 181 The files in the "maint" directory of the PCRE source contain data, scripts,
5 ph10 122 and programs that are used for the maintenance of PCRE, but which do not form
6 ph10 181 part of the PCRE distribution tarballs. This document describes these files and
7 ph10 122 also contains some notes for maintainers. Its contents are:
8 ph10 97
9 ph10 122 Files in the maint directory
10     Updating to a new Unicode release
11     Preparing for a PCRE release
12     Making a PCRE release
13 ph10 181 Long-term ideas (wish list)
14 ph10 122
15    
16     Files in the maint directory
17 ph10 507 ============================
18 ph10 122
19 ph10 507 ---------------- This file is now OBSOLETE and no longer used ----------------
20 ph10 129 Builducptable A Perl script that creates the contents of the ucptable.h file
21     from two Unicode data files, which themselves are downloaded
22     from the Unicode web site. Run this script in the "maint"
23     directory.
24 ph10 507 ---------------- This file is now OBSOLETE and no longer used ----------------
25 ph10 181
26 ph10 351 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 ph10 535 offsets, which is tedious to maintain by hand.
29 ph10 351
30 ph10 129 ManyConfigTests A shell script that runs "configure, make, test" a number of
31     times with different configuration settings.
32 ph10 535
33 ph10 350 MultiStage2.py A Python script that generates the file pcre_ucd.c from three
34     Unicode data tables, which are themselves downloaded from the
35 ph10 535 Unicode web site. Run this script in the "maint" directory.
36 ph10 350 The generated file contains the tables for a 2-stage lookup
37 ph10 535 of Unicode properties.
38 ph10 583
39 ph10 539 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 ph10 583 used for testing from time to time.
44 ph10 181
45 ph10 454 README This file.
46    
47 ph10 535 Unicode.tables The files in this directory, DerivedGeneralCategory.txt,
48 ph10 350 Scripts.txt and UnicodeData.txt, were downloaded from the
49     Unicode web site. They contain information about Unicode
50     characters and scripts.
51 ph10 181
52 ph10 350 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 ph10 351 the "maint" directory (see comments at its head).
56 ph10 181
57 ph10 129 ucptestdata A directory containing two files, testinput1 and testoutput1,
58     to use in conjunction with the ucptest program.
59 ph10 181
60 ph10 129 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
62     versa. If its argument is a hex number such as 0x1234, it
63     outputs a list of the equivalent UTF-8 bytes. If its argument
64     is sequence of concatenated UTF-8 bytes (e.g. e188b4) it
65     treats them as a UTF-8 character and outputs the equivalent
66     code point in hex.
67 ph10 97
68 ph10 181
69 ph10 122 Updating to a new Unicode release
70 ph10 507 =================================
71 ph10 122
72 ph10 181 When there is a new release of Unicode, the files in Unicode.tables must be
73 ph10 454 refreshed from the web site. If the new version of Unicode adds new character
74 ph10 352 scripts, the source file ucp.h and both the MultiStage2.py and the
75 ph10 454 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 ph10 122
79 ph10 491 If MultiStage2.py gives the error "ValueError: list.index(x): x not in list",
80 ph10 535 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 ph10 491 in which they were introduced:
84    
85     http://en.wikipedia.org/wiki/Unicode_scripts#Table_of_Unicode_scripts
86    
87 ph10 454 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 ph10 491 of test characters. The source file ucptest.c must be updated whenever new
90     Unicode script names are added.
91 ph10 122
92 ph10 535 Note also that both the pcresyntax.3 and pcrepattern.3 man pages contain lists
93 ph10 491 of Unicode script names.
94 ph10 351
95 ph10 491
96 ph10 122 Preparing for a PCRE release
97 ph10 507 ============================
98 ph10 122
99     This section contains a checklist of things that I consult before building a
100     distribution for a new release.
101    
102 ph10 454 . Ensure that the version number and version date are correct in configure.ac.
103 ph10 535
104 ph10 292 . If new build options have been added, ensure that they are added to the CMake
105 ph10 535 files as well as to the autoconf files.
106 ph10 122
107     . Run ./autogen.sh to ensure everything is up-to-date.
108    
109 ph10 181 . Compile and test with many different config options, and combinations of
110 ph10 129 options. The maint/ManyConfigTests script now encapsulates this testing.
111 ph10 181
112 ph10 579 . Run perltest.pl on the test data for tests 1, 4, 6, and 11. The output should
113     match the PCRE test output, apart from the version identification at the
114     start of each test. The other tests are not Perl-compatible (they use various
115     PCRE-specific features or options).
116 ph10 122
117     . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest
118     valgrind", though that takes quite a long time.
119 ph10 181
120 ph10 583 . It is possible to test with the emulated memmove() function by undefining
121     HAVE_MEMMOVE and HAVE_BCOPY in config.h, though I do not do this often. You
122     may see a number of "pcre_memmove defined but not used" warnings for the
123     modules in which there is no call to memmove(). These can be ignored.
124 ph10 122
125 ph10 535 . Documentation: check AUTHORS, COPYING, ChangeLog (check version and date),
126 ph10 454 INSTALL, LICENCE, NEWS (check version and date), NON-UNIX-USE, and README.
127     Many of these won't need changing, but over the long term things do change.
128 ph10 181
129 ph10 583 . I used to test new releases myself on a number of different operating
130     systems, using different compilers as well. For example, on Solaris it is
131     helpful to test using Sun's cc compiler as a change from gcc. Adding
132     -xarch=v9 to the cc options does a 64-bit test, but it also needs -S 64 for
133     pcretest to increase the stack size for test 2. Since I retired I can no
134     longer do this, but instead I rely on putting out release candidates for
135     folks on the pcre-dev list to test.
136 ph10 122
137    
138     Making a PCRE release
139 ph10 507 =====================
140 ph10 122
141     Run PrepareRelease and commit the files that it changes (by removing trailing
142 ph10 583 spaces). The first thing this script does is to run CheckMan on the man pages;
143     if it finds any markup errors, it reports them and then aborts.
144 ph10 122
145 ph10 583 Once PrepareRelease has run clean, run "make distcheck" to create the tarballs
146     and the zipball. Double-check with "svn status", then create an SVN tagged
147     copy:
148    
149 ph10 212 svn copy svn://vcs.exim.org/pcre/code/trunk \
150 ph10 535 svn://vcs.exim.org/pcre/code/tags/pcre-8.xx
151 ph10 212
152 ph10 122 Don't forget to update Freshmeat when the new release is out, and to tell
153 ph10 535 webmaster@pcre.org and the mailing list. Also, update the list of version
154 ph10 507 numbers in Bugzilla (edit products).
155 ph10 122
156    
157     Future ideas (wish list)
158 ph10 507 ========================
159 ph10 122
160     This section records a list of ideas so that they do not get forgotten. They
161 ph10 181 vary enormously in their usefulness and potential for implementation. Some are
162 ph10 122 very sensible; some are rather wacky. Some have been on this list for years;
163     others are relatively new.
164    
165     . Optimization
166    
167 ph10 181 There are always ideas for new optimizations so as to speed up pattern
168     matching. Most of them try to save work by recognizing a non-match without
169 ph10 122 having to scan all the possibilities. These are some that I've recorded:
170    
171     * /((A{0,5}){0,5}){0,5}(something complex)/ on a non-matching string is very
172     slow, though Perl is fast. Can we speed up somehow? Convert to {0,125}?
173 ph10 181 OTOH, this is pathological - the user could easily fix it.
174    
175 ph10 122 * Turn ={4} into ==== ? (for speed). I once did an experiment, and it seems
176     to have little effect, and maybe makes things worse.
177 ph10 181
178     * "Ends with literal string" - note that a single character doesn't gain much
179 ph10 454 over the existing "required byte" (reqbyte) feature that just remembers one
180 ph10 122 byte.
181 ph10 181
182 ph10 535 * These probably need to go in pcre_study():
183 ph10 181
184 ph10 122 o Remember an initial string rather than just 1 char?
185 ph10 181
186 ph10 122 o A required byte from alternatives - not just the last char, but an
187     earlier one if common to all alternatives.
188 ph10 181
189 ph10 122 o Friedl contains other ideas.
190 ph10 535
191     * pcre_study() does not set initial byte flags for Unicode property types
192     such as \p; I don't know how much benefit there would be for, for example,
193     setting the bits for 0-9 and all bytes >= xC0 when a pattern starts with
194     \p{N}.
195    
196     * There is scope for more "auto-possessifying" in connection with \p and \P.
197    
198 ph10 122 . If Perl gets to a consistent state over the settings of capturing sub-
199     patterns inside repeats, see if we can match it. One example of the
200     difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE
201     leaves $2 set. In Perl, it's unset. Changing this in PCRE will be very hard
202     because I think it needs much more state to be remembered.
203    
204 ph10 181 . Perl 6 will be a revolution. Is it a revolution too far for PCRE?
205    
206 ph10 122 . Unicode
207    
208 ph10 583 * There has been a request for direct support of 16-bit characters and
209     UTF-16 (Bugzilla #1049). However, since Unicode is moving beyond purely
210     16-bit characters, is this worth it at all? One possible way of handling
211     16-bit characters would be to "load" them in the same way that UTF-8
212     characters are loaded. Another possibility is to provide a set of
213     translation functions, and build an index during translation so that the
214     returned offsets can automatically be translated (using the index) after a
215     match.
216    
217 ph10 122 * A different approach to Unicode might be to use a typedef to do everything
218     in unsigned shorts instead of unsigned chars. Actually, we'd have to have a
219     new typedef to distinguish data from bits of compiled pattern that are in
220     bytes, I think. There would need to be conversion functions in and out. I
221     don't think this is particularly trivial - and anyway, Unicode now has
222 ph10 583 characters that need more than 16 bits, so is this at all sensible? I
223     suspect not.
224 ph10 181
225 ph10 122 . Allow errorptr and erroroffset to be NULL. I don't like this idea.
226    
227     . Line endings:
228    
229     * Option to use NUL as a line terminator in subject strings. This could now
230     be done relatively easily since the extension to support LF, CR, and CRLF.
231 ph10 454 If it is done, a suitable option for pcregrep is also required.
232 ph10 181
233 ph10 122 . Option to provide the pattern with a length instead of with a NUL terminator.
234 ph10 454 This affects quite a few places in the code and is not trivial.
235 ph10 122
236 ph10 181 . Catch SIGSEGV for stack overflows?
237 ph10 122
238     . A feature to suspend a match via a callout was once requested.
239    
240     . Option to convert results into character offsets and character lengths.
241    
242 ph10 181 . Option for pcregrep to scan only the start of a file. I am not keen - this is
243 ph10 122 the job of "head".
244 ph10 181
245     . A (non-Unix) user wanted pcregrep options to (a) list a file name just once,
246 ph10 122 preceded by a blank line, instead of adding it to every matched line, and (b)
247     support --outputfile=name.
248 ph10 181
249 ph10 454 . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 8.
250 ph10 122
251 ph10 181 . Add a user pointer to pcre_malloc/free functions -- some option would be
252 ph10 122 needed to retain backward compatibility.
253 ph10 181
254 ph10 122 . Define a union for the results from pcre_fullinfo().
255    
256 ph10 181 . Provide a "random access to the subject" facility so that the way in which it
257     is stored is independent of PCRE. For efficiency, it probably isn't possible
258 ph10 122 to switch this dynamically. It would have to be specified when PCRE was
259     compiled. PCRE would then call a function every time it wanted a character.
260 ph10 181
261 ph10 122 . Wild thought: the ability to compile from PCRE's internal byte code to a real
262     FSM and a very fast (third) matcher to process the result. There would be
263     even more restrictions than for pcre_dfa_exec(), however. This is not easy.
264 ph10 181
265 ph10 122 . Should pcretest have some private locale data, to avoid relying on the
266     available locales for the test data, since different OS have different ideas?
267     This won't be as thorough a test, but perhaps that doesn't really matter.
268 ph10 181
269     . pcregrep: add -rs for a sorted recurse? Having to store file names and sort
270 ph10 122 them will of course slow it down.
271    
272 ph10 181 . Someone suggested --disable-callout to save code space when callouts are
273     never wanted. This seems rather marginal.
274 ph10 535
275     . Check names that consist entirely of digits: PCRE allows, but do Perl and
276     Python, etc?
277    
278     . A user suggested a parameter to limit the length of string matched, for
279     example if the parameter is N, the current match should fail if the matched
280     substring exceeds N. This could apply to both match functions. The value
281 ph10 372 could be a new field in the extra block.
282 ph10 535
283 ph10 372 . Callouts with arguments: (?Cn:ARG) for instance.
284 ph10 122
285 ph10 535 . A user is going to supply a patch to generalize the API for user-specific
286 ph10 507 memory allocation so that it is more flexible in threaded environments. This
287 ph10 454 was promised a long time ago, and never appeared...
288 ph10 535
289 ph10 454 . Write a function that generates random matching strings for a compiled regex.
290 ph10 372
291 ph10 535 . Write a wrapper to maintain a structure with specified runtime parameters,
292     such as recurse limit, and pass these to PCRE each time it is called. Also
293 ph10 454 maybe malloc and free. A user sent a prototype.
294 ph10 535
295     . Pcregrep: an option to specify the output line separator, either as a string
296     or select from a fixed list. This is not dead easy, because at the moment it
297 ph10 454 outputs whatever is in the input file.
298 ph10 535
299     . Improve the code for duplicate checking in pcre_dfa_exec(). An incomplete,
300     non-thread-safe patch showed that this can help performance for patterns
301     where there are many alternatives. However, a simple thread-safe
302     implementation that I tried made things worse in many simple cases, so this
303 ph10 454 is not an obviously good thing.
304 ph10 535
305     . Make the longest lookbehind available via pcre_fullinfo(). This is not
306     straightforward because lookbehinds can be nested inside lookbehinds. This
307     case will have to be identified, and the amounts added. This should then give
308     the maximum possible lookbehind length. The reason for wanting this is to
309 ph10 454 help when implementing multi-segment matching using pcre_exec() with partial
310     matching and overlapping segments.
311 ph10 535
312 ph10 454 . PCRE cannot at present distinguish between subpatterns with different names,
313 ph10 535 but the same number (created by the use of ?|). In order to do so, a way of
314 ph10 454 remembering *which* subpattern numbered n matched is needed. Bugzilla #760.
315 ph10 535 Now that (*MARK) has been implemented, it can perhaps be used as a way round
316     this problem.
317    
318     . Instead of having #ifdef HAVE_CONFIG_H in each module, put #include
319 ph10 507 "something" and the the #ifdef appears only in one place, in "something".
320 ph10 454
321 ph10 122 Philip Hazel
322     Email local part: ph10
323     Email domain: cam.ac.uk
324 ph10 583 Last updated: 12 January 2011

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12