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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
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"  README           This file.
40                   directory.  
41    Unicode.tables   The files in this directory, DerivedGeneralCategory.txt,
42                     Scripts.txt and UnicodeData.txt, were downloaded from the
43                     Unicode web site. They contain information about Unicode
44                     characters and scripts.
45    
46    ucptest.c        A short C program for testing the Unicode property macros
47                     that do lookups in the pcre_ucd.c data, mainly useful after
48                     rebuilding the Unicode property table. Compile and run this in
49                     the "maint" directory (see comments at its head).
50    
51  ucptestdata      A directory containing two files, testinput1 and testoutput1,  ucptestdata      A directory containing two files, testinput1 and testoutput1,
52                   to use in conjunction with the ucptest program.                   to use in conjunction with the ucptest program.
53    
54  utf8.c           A short, freestanding C program for converting a Unicode code  utf8.c           A short, freestanding C program for converting a Unicode code
55                   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
56                   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 58  utf8.c           A short, freestanding C
58                   is sequence of concatenated UTF-8 bytes (e.g. e188b4) it                   is sequence of concatenated UTF-8 bytes (e.g. e188b4) it
59                   treats them as a UTF-8 character and outputs the equivalent                   treats them as a UTF-8 character and outputs the equivalent
60                   code point in hex.                   code point in hex.
61    
62    
63  Updating to a new Unicode release  Updating to a new Unicode release
64  ---------------------------------  ---------------------------------
65    
66  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
67  refreshed from the web site, and the Buildupctable script can then be run to  refreshed from the web site. If the new version of Unicode adds new character
68  generate a new version of ucptable.h. The ucptest program can be used to check  scripts, the source file ucp.h and both the MultiStage2.py and the
69  that the resulting table works properly, using the data files in ucptestdata to  GenerateUtt.py scripts must be edited to add the new names. Then MultiStage2.py
70  check a number of test characters.  can be run to generate a new version of pcre_ucd.c, and GenerateUtt.py can be
71    run to generate the tricky tables for inclusion in pcre_tables.c.
72    
73    The ucptest program can be compiled and used to check that the new tables in
74    pcre_ucd.c work properly, using the data files in ucptestdata to check a number
75    of test characters.
76    
77    
78  Preparing for a PCRE release  Preparing for a PCRE release
# Line 61  Preparing for a PCRE release Line 81  Preparing for a PCRE release
81  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
82  distribution for a new release.  distribution for a new release.
83    
84  . 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.
85    ChangeLog, and NEWS.  
86    . If new build options have been added, ensure that they are added to the CMake
87      files as well as to the autoconf files.
88    
89  . Run ./autogen.sh to ensure everything is up-to-date.  . Run ./autogen.sh to ensure everything is up-to-date.
90    
91  . Compile and test with many different config options, and combinations of  . Compile and test with many different config options, and combinations of
92    options. The maint/ManyConfigTests script now encapsulates this testing.    options. The maint/ManyConfigTests script now encapsulates this testing.
93    
94  . 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
95    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 output
96    other tests are not Perl-compatible (they use various special PCRE options).    should match the PCRE test output, apart from the version identification at
97      the start of each test. The other tests are not Perl-compatible (they use
98      various PCRE-specific features or options).
99    
100  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest
101    valgrind", though that takes quite a long time.    valgrind", though that takes quite a long time.
102    
103  . It may also useful to test with Electric Fence, though the fact that it  . It may also useful to test with Electric Fence, though the fact that it
104    grumbles for missing free() calls can be a nuisance. (A missing free() in    grumbles for missing free() calls can be a nuisance. (A missing free() in
105    pcretest is hardly a big problem.) To build with EF, use:    pcretest is hardly a big problem.) To build with EF, use:
106    
107      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.
108    
109    Then all normal runs use it to check for buffer overflow. Also run everything    Then all normal runs use it to check for buffer overflow. Also run everything
110    with:    with:
111    
112      EF_PROTECT_BELOW=1 <whatever>      EF_PROTECT_BELOW=1 <whatever>
113    
114    because there have been problems with lookbehinds that looked too far.    because there have been problems with lookbehinds that looked too far.
115    
116  . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and  . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and
117    HAVE_BCOPY in config.h. You may see a number of "pcre_memmove defined but not    HAVE_BCOPY in config.h. You may see a number of "pcre_memmove defined but not
118    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
119    can be ignored.    can be ignored.
120    
121  . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,  . Documentation: check AUTHORS, COPYING, ChangeLog (check version and date),
122    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.
123    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.
124    
125  . 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
126    that indicates a markup error.    that indicates a markup error.
127    
128  . 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
129    systems if possible, and using different compilers as well. For example,    systems if possible, and using different compilers as well. For example,
130    on Solaris it is helpful to test using Sun's cc compiler as a change from    on Solaris it is helpful to test using Sun's cc compiler as a change from
131    gcc. Adding -xarch=v9 to the cc options does a 64-bit test, but it also    gcc. Adding -xarch=v9 to the cc options does a 64-bit test, but it also
# Line 113  Making a PCRE release Line 137  Making a PCRE release
137    
138  Run PrepareRelease and commit the files that it changes (by removing trailing  Run PrepareRelease and commit the files that it changes (by removing trailing
139  spaces). Then run "make distcheck" to create the tarballs and the zipball.  spaces). Then run "make distcheck" to create the tarballs and the zipball.
140    Double-check with "svn status", then create an SVN tagged copy:
141    
142      svn copy svn://vcs.exim.org/pcre/code/trunk \
143               svn://vcs.exim.org/pcre/code/tags/pcre-8.xx
144    
145  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
146  webmaster@pcre.org and the mailing list.  webmaster@pcre.org and the mailing list.
# Line 122  Future ideas (wish list) Line 150  Future ideas (wish list)
150  ------------------------  ------------------------
151    
152  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
153  vary enormously in their usefulness and potential for implementation. Some are  vary enormously in their usefulness and potential for implementation. Some are
154  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;
155  others are relatively new.  others are relatively new.
156    
157  . Optimization  . Optimization
158    
159    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
160    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
161    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:
162    
163    * /((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
164      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}?
165      OTOH, this is pathological - the user could easily fix it.      OTOH, this is pathological - the user could easily fix it.
166    
167    * 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
168      to have little effect, and maybe makes things worse.      to have little effect, and maybe makes things worse.
169    
170    * "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
171      over the existing "required byte" (reqbyte) feature that just saves one      over the existing "required byte" (reqbyte) feature that just remembers one
172      byte.      byte.
173    
174    * These probably need to go in study():    * These probably need to go in study():
175    
176      o Remember an initial string rather than just 1 char?      o Remember an initial string rather than just 1 char?
177    
178      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
179        earlier one if common to all alternatives.        earlier one if common to all alternatives.
180    
     o Minimum length of subject needed.  
   
181      o Friedl contains other ideas.      o Friedl contains other ideas.
182    
183  . 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-
# Line 159  others are relatively new. Line 185  others are relatively new.
185    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE
186    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
187    because I think it needs much more state to be remembered.    because I think it needs much more state to be remembered.
188    
189  . 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?
190    
191  . Unicode  . Unicode
192    
193    * Note that in Perl, \s matches \pZ and similarly for \d, \w and the POSIX    * Note that in Perl, \s matches \pZ and similarly for \d, \w and the POSIX
194      character classes. For the moment, I've chosen not to support this for      character classes. For the moment, I've chosen not to support this for
195      backward compatibility, for speed, and because it would be messy to      backward compatibility, for speed, and because it would be messy to
196      implement.      implement.
197    
198    * 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
199      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
200      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
201      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
202      don't think this is particularly trivial - and anyway, Unicode now has      don't think this is particularly trivial - and anyway, Unicode now has
203      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?
204    
205    * There has been a request for direct support of 16-bit characters and    * There has been a request for direct support of 16-bit characters and
206      UTF-16. However, since Unicode is moving beyond purely 16-bit characters,      UTF-16. However, since Unicode is moving beyond purely 16-bit characters,
207      is this worth it at all? One possible way of handling 16-bit characters      is this worth it at all? One possible way of handling 16-bit characters
208      would be to "load" them in the same way that UTF-8 characters are loaded.      would be to "load" them in the same way that UTF-8 characters are loaded.
209    
210  . 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.
211    
212  . Line endings:  . Line endings:
213    
214    * 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
215      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.
216      If this is done, a suitable option for pcregrep is also required.      If it is done, a suitable option for pcregrep is also required.
217    
218  . 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.
219    This probably affects quite a few places in the code.    This affects quite a few places in the code and is not trivial.
220    
221  . 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.  
222    
223  . A feature to suspend a match via a callout was once requested.  . A feature to suspend a match via a callout was once requested.
224    
225  . Option to convert results into character offsets and character lengths.  . Option to convert results into character offsets and character lengths.
226    
227  . 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
228    the job of "head".    the job of "head".
229    
230  . 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,
231    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)
232    support --outputfile=name.    support --outputfile=name.
   
 . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 7.  
233    
234  . 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.
235    
236    . Add a user pointer to pcre_malloc/free functions -- some option would be
237    needed to retain backward compatibility.    needed to retain backward compatibility.
238    
239  . Define a union for the results from pcre_fullinfo().  . Define a union for the results from pcre_fullinfo().
240    
241  . 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
242    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
243    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
244    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.
245    
 . 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.  
   
246  . 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
247    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
248    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.
249    
250  . Should pcretest have some private locale data, to avoid relying on the  . Should pcretest have some private locale data, to avoid relying on the
251    available locales for the test data, since different OS have different ideas?    available locales for the test data, since different OS have different ideas?
252    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.
   
 . pcregrep: add -rs for a sorted recurse? Having to store file names and sort  
   them will of course slow it down.  
253    
254  . Re-arrange test 2: take out the link-size dependent stuff for a separate test  . pcregrep: add -rs for a sorted recurse? Having to store file names and sort
255    that is run only when the link size *is* 2; leave in some non-numbered    them will of course slow it down.
   debugging tests using the new /Z feature.  
   
 . Stan Switzer's goto replacement for longjmp, which is apparently very slow on  
   OS-X. This is used when stack recursion is disabled. It would be worth doing  
   some timing tests on other OS.  
256    
257  . Someone suggested --disable-callout to save code space when callouts are  . Someone suggested --disable-callout to save code space when callouts are
258    never wanted. This seems rather marginal.    never wanted. This seems rather marginal.
259    
260  . Work needs doing so that the pcregrep tests work better with different  . Check names that consist entirely of digits: PCRE allows, but do Perl and
261    linebreak settings. Currently, some tests don't work when the input files    Python, etc?
   do not have \n line endings.  
262    
263  . If the fr_FR locale isn't available for testing, try "french" instead,  . A user suggested a parameter to limit the length of string matched, for
264    because this may be available on Windows. It means modifying the test data,    example if the parameter is N, the current match should fail if the matched
265    however.    substring exceeds N. This could apply to both match functions. The value
266      could be a new field in the extra block.
267    
268    . Callouts with arguments: (?Cn:ARG) for instance.
269    
270    . A user is going to supply a patch to generalize the API for user-specific
271      memory allocation so that it is more flexible in threaded environments. Thiw
272      was promised a long time ago, and never appeared...
273    
274    . Write a function that generates random matching strings for a compiled regex.
275    
276    . Write a wrapper to maintain a structure with specified runtime parameters,
277      such as recurse limit, and pass these to PCRE each time it is called. Also
278      maybe malloc and free. A user sent a prototype.
279    
280    . Pcregrep: an option to specify the output line separator, either as a string
281      or select from a fixed list. This is not dead easy, because at the moment it
282      outputs whatever is in the input file.
283    
284    . Improve the code for duplicate checking in pcre_dfa_exec(). An incomplete,
285      non-thread-safe patch showed that this can help performance for patterns
286      where there are many alternatives. However, a simple thread-safe
287      implementation that I tried made things worse in many simple cases, so this
288      is not an obviously good thing.
289    
290    . Make the longest lookbehind available via pcre_fullinfo(). This is not
291      straightforward because lookbehinds can be nested inside lookbehinds. This
292      case will have to be identified, and the amounts added. This should then give
293      the maximum possible lookbehind length. The reason for wanting this is to
294      help when implementing multi-segment matching using pcre_exec() with partial
295      matching and overlapping segments.
296    
297    . PCRE cannot at present distinguish between subpatterns with different names,
298      but the same number (created by the use of ?|). In order to do so, a way of
299      remembering *which* subpattern numbered n matched is needed. Bugzilla #760.
300    
301  Philip Hazel  Philip Hazel
302  Email local part: ph10  Email local part: ph10
303  Email domain: cam.ac.uk  Email domain: cam.ac.uk
304  Last updated: 24 April 2007  Last updated: 26 September 2009

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