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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  Builducptable   A Perl script that creates the contents of the ucptable.h file  ----------------- This file is now OBSOLETE and no longer used ----------------
20                  from two Unicode data files, which themselves are downloaded  Builducptable    A Perl script that creates the contents of the ucptable.h file
21                  from the Unicode web site. Run this script in the "maint"                   from two Unicode data files, which themselves are downloaded
22                  directory.                   from the Unicode web site. Run this script in the "maint"
23                     directory.
24  Tech.Notes      Some notes about the internals of the PCRE code.  ----------------- This file is now OBSOLETE and no longer used ----------------
25    
26  Unicode.tables  The files in this directory, Scripts.txt and UnicodeData.txt,  GenerateUtt.py   A Python script to generate part of the pcre_tables.c file
27                  were downloaded from the Unicode web site. They contain                   that contains Unicode script names in a long string with
28                  information about Unicode characters and scripts.                   offsets, which is tedious to maintain by hand.
29    
30  ucptest.c       A short C program for testing the Unicode property functions in  ManyConfigTests  A shell script that runs "configure, make, test" a number of
31                  pcre_ucp_searchfuncs.c, mainly useful after rebuilding the                   times with different configuration settings.
32                  Unicode property table. Compile and run this in the "maint"  
33                  directory.  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  ucptestdata     A directory containing two files, testinput1 and testoutput1,                   Unicode web site. Run this script in the "maint" directory.
36                  to use in conjunction with the ucptest program.                   The generated file contains the tables for a 2-stage lookup
37                     of Unicode properties.
38  utf8.c          A short, freestanding C program for converting a Unicode code  
39                  point into a sequence of bytes in the UTF-8 encoding, and vice  Unicode.tables   The files in this directory, DerivedGeneralCategory.txt,
40                  versa. If its argument is a hex number such as 0x1234, it                   Scripts.txt and UnicodeData.txt, were downloaded from the
41                  outputs a list of the equivalent UTF-8 bytes. If its argument                   Unicode web site. They contain information about Unicode
42                  is sequence of concatenated UTF-8 bytes (e.g. e188b4) it treats                   characters and scripts.
43                  them as a UTF-8 character and outputs the equivalent code point  
44                  in hex.  ucptest.c        A short C program for testing the Unicode property macros
45                     that do lookups in the pcre_ucd.c data, mainly useful after
46                     rebuilding the Unicode property table. Compile and run this in
47                     the "maint" directory (see comments at its head).
48    
49    ucptestdata      A directory containing two files, testinput1 and testoutput1,
50                     to use in conjunction with the ucptest program.
51    
52    utf8.c           A short, freestanding C program for converting a Unicode code
53                     point into a sequence of bytes in the UTF-8 encoding, and vice
54                     versa. If its argument is a hex number such as 0x1234, it
55                     outputs a list of the equivalent UTF-8 bytes. If its argument
56                     is sequence of concatenated UTF-8 bytes (e.g. e188b4) it
57                     treats them as a UTF-8 character and outputs the equivalent
58                     code point in hex.
59    
60    
61  Updating to a new Unicode release  Updating to a new Unicode release
62  ---------------------------------  ---------------------------------
63    
64  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
65  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
66  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
67  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 the
68  check a number of test characters.  MultiStage2.py script can then be run to generate a new version of pcre_ucd.c
69    and the GenerateUtt.py can be run to generate the tricky tables for inclusion
70    in pcre_tables.c.
71    
72    The ucptest program can then be compiled and used to check that the new tables
73    in pcre_ucd.c work properly, using the data files in ucptestdata to check a
74    number of test characters.
75    
76    
77  Preparing for a PCRE release  Preparing for a PCRE release
# Line 60  Preparing for a PCRE release Line 80  Preparing for a PCRE release
80  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
81  distribution for a new release.  distribution for a new release.
82    
83  . 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,
84      ChangeLog, and NEWS.
85    
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:    options. The maint/ManyConfigTests script now encapsulates this testing.
93    
    * Totally standard ./configure with no options  
    * --disable-shared  
    * --disable-static  
    * --enable-utf8  
    * --enable-unicode-properties  
    * --disable-cpp  
    * --with-link-size=3 (occasionally check with 4 as well)  
    * --disable-stack-for-recursion  
    * --enable-newline-is-any  
   
   I've never automated this, but perhaps I should. The newline testing could be  
   enhanced; at present, some tests fail unless plain LF is a newline.  
   
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 and 4. The output should match
95    the PCRE test output, apart from the version identification at the top. The    the PCRE test output, apart from the version identification at the top. The
96    other tests are not Perl-compatible (they use various special PCRE options).    other tests are not Perl-compatible (they use various special PCRE options).
97    
 . Test on a number of different operating systems. In particular, at the moment  
   I can test on Solaris, 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. I also test on FreeBSD and  
   Linux (where I develop).  
   
98  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest
99    valgrind", though that takes quite a long time.    valgrind", though that takes quite a long time.
100    
101  . It can 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
102    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
103    pcretest is hardly a big problem.) To build with EF, use:    pcretest is hardly a big problem.) To build with EF, use:
104    
105      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.
106    
107    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
108    with:    with:
   
     EF_PROTECT_BELOW=1 <whatever>  
   
   because there have been problems with lookbehinds that looked too far.  
   
 . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and  
   HAVE_BCOPY in config.h.  
109    
110  . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,      EF_PROTECT_BELOW=1 <whatever>
111    LICENCE, NEWS (check date), NON-UNIX-USE, and README. Many of these won't  
112      because there have been problems with lookbehinds that looked too far.
113    
114    . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and
115      HAVE_BCOPY in config.h. You may see a number of "pcre_memmove defined but not
116      used" warnings for the modules in which there is no call to memmove(). These
117      can be ignored.
118    
119    . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,
120      LICENCE, NEWS (check date), NON-UNIX-USE, and README. Many of these won't
121    need changing, but over the long term things do change.    need changing, but over the long term things do change.
122    
123  . 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
124    that indicates a markup error.    that indicates a markup error.
125    
126    . When the release is built, test it on a number of different operating
127      systems if possible, and using different compilers as well. For example,
128      on Solaris it is helpful to test using Sun's cc compiler as a change from
129      gcc. Adding -xarch=v9 to the cc options does a 64-bit test, but it also
130      needs -S 64 for pcretest to increase the stack size for test 2.
131    
132    
133  Making a PCRE release  Making a PCRE release
134  ---------------------  ---------------------
135    
136  Run PrepareRelease and commit the files that it changes (by removing trailing  Run PrepareRelease and commit the files that it changes (by removing trailing
137  spaces). Then run "make dist" to create the tarballs and the zipball.  spaces). Then run "make distcheck" to create the tarballs and the zipball.
138    Double-check with "svn status", then create an SVN tagged copy:
139    
140      svn copy svn://vcs.exim.org/pcre/code/trunk \
141               svn://vcs.exim.org/pcre/code/tags/pcre-7.x
142    
143  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
144  webmaster@pcre.org and the mailing list.  webmaster@pcre.org and the mailing list.
# Line 131  Future ideas (wish list) Line 148  Future ideas (wish list)
148  ------------------------  ------------------------
149    
150  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
151  vary enormously in their usefulness and potential for implementation. Some are  vary enormously in their usefulness and potential for implementation. Some are
152  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;
153  others are relatively new.  others are relatively new.
154    
155  . Optimization  . Optimization
156    
157    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
158    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
159    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:
160    
161    * /((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
162      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}?
163      OTOH, this is pathological - the user could easily fix it.      OTOH, this is pathological - the user could easily fix it.
164    
165    * 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
166      to have little effect, and maybe makes things worse.      to have little effect, and maybe makes things worse.
167    
168    * "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
169      over the existing "required byte" (reqbyte) feature that just saves one      over the existing "required byte" (reqbyte) feature that just saves one
170      byte.      byte.
171    
172    * These probably need to go in study():    * These probably need to go in study():
173    
174      o Remember an initial string rather than just 1 char?      o Remember an initial string rather than just 1 char?
175    
176      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
177        earlier one if common to all alternatives.        earlier one if common to all alternatives.
178    
179      o Minimum length of subject needed.      o Minimum length of subject needed.
180    
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-
184    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
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 this 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 probably affects quite a few places in the code.
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.
233    
234  . 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 > 7.
235    
236  . 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
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.
253    
254  . 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
255    them will of course slow it down.    them will of course slow it down.
256    
257  . 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
258    that is run only when the link size *is* 2; leave in some non-numbered    never wanted. This seems rather marginal.
   debugging tests using the new /Z feature.  
259    
260  . Stan Switzer's goto replacement for longjmp, which is apparently very slow on  . Check names that consist entirely of digits: PCRE allows, but do Perl and
261    OS-X. This is used when stack recursion is disabled. It would be worth doing    Python, etc?
262    some timing tests on other OS.  
263    . A user suggested a parameter to limit the length of string matched, for
264  . Someone suggested --disable-callout to save code space when callouts are    example if the parameter is N, the current match should fail if the matched
265    never wanted. This seems rather marginal.    substring exceeds N. This could apply to both match functions. The value
266      could be a new field in the extra block.
 . Automate some of the testing before release into a script that compiles with  
   different options and runs the tests in each case.  
267    
268  . How about distributing a fixed pcre_chartables.c file and abandoning the  . Callouts with arguments: (?Cn:ARG) for instance.
269    on-the-fly generation using dftables. This will make cross-compiling easier,  
270    and in any case, locales are going out of fashion.  . 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.
272    
273  Philip Hazel  Philip Hazel
274  Email local part: ph10  Email local part: ph10
275  Email domain: cam.ac.uk  Email domain: cam.ac.uk
276  Last updated: 12 March 2007  Last updated: 26 August 2008

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