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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  Builducptable    A Perl script that creates the contents of the ucptable.h file
20                  from two Unicode data files, which themselves are downloaded                   from two Unicode data files, which themselves are downloaded
21                  from the Unicode web site. Run this script in the "maint"                   from the Unicode web site. Run this script in the "maint"
22                  directory.                   directory.
23    
24  Tech.Notes      Some notes about the internals of the PCRE code.  ManyConfigTests  A shell script that runs "configure, make, test" a number of
25                     times with different configuration settings.
26  Unicode.tables  The files in this directory, Scripts.txt and UnicodeData.txt,  
27                  were downloaded from the Unicode web site. They contain  Unicode.tables   The files in this directory, Scripts.txt and UnicodeData.txt,
28                  information about Unicode characters and scripts.                   were downloaded from the Unicode web site. They contain
29                     information about Unicode characters and scripts.
30  ucptest.c       A short C program for testing the Unicode property functions in  
31                  pcre_ucp_searchfuncs.c, mainly useful after rebuilding the  ucptest.c        A short C program for testing the Unicode property functions
32                  Unicode property table. Compile and run this in the "maint"                   in pcre_ucp_searchfuncs.c, mainly useful after rebuilding the
33                  directory.                   Unicode property table. Compile and run this in the "maint"
34                     directory.
35  ucptestdata     A directory containing two files, testinput1 and testoutput1,  
36                  to use in conjunction with the ucptest program.  ucptestdata      A directory containing two files, testinput1 and testoutput1,
37                     to use in conjunction with the ucptest program.
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  utf8.c           A short, freestanding C program for converting a Unicode code
40                  versa. If its argument is a hex number such as 0x1234, it                   point into a sequence of bytes in the UTF-8 encoding, and vice
41                  outputs a list of the equivalent UTF-8 bytes. If its argument                   versa. If its argument is a hex number such as 0x1234, it
42                  is sequence of concatenated UTF-8 bytes (e.g. e188b4) it treats                   outputs a list of the equivalent UTF-8 bytes. If its argument
43                  them as a UTF-8 character and outputs the equivalent code point                   is sequence of concatenated UTF-8 bytes (e.g. e188b4) it
44                  in hex.                   treats them as a UTF-8 character and outputs the equivalent
45                     code point in hex.
46    
47    
48  Updating to a new Unicode release  Updating to a new Unicode release
49  ---------------------------------  ---------------------------------
50    
51  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
52  refreshed from the web site, and the Buildupctable script can then be run to  refreshed from the web site, and the Buildupctable script can then be run to
53  generate a new version of ucptable.h. The ucptest program can be used to check  generate a new version of ucptable.h. The ucptest program can be used to check
54  that the resulting table works properly, using the data files in ucptestdata to  that the resulting table works properly, using the data files in ucptestdata to
55  check a number of test characters.  check a number of test characters.
56    
57    
58  Preparing for a PCRE release  Preparing for a PCRE release
# Line 60  Preparing for a PCRE release Line 61  Preparing for a PCRE release
61  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
62  distribution for a new release.  distribution for a new release.
63    
64  . 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,
65      ChangeLog, and NEWS.
66    
67  . Run ./autogen.sh to ensure everything is up-to-date.  . Run ./autogen.sh to ensure everything is up-to-date.
68    
69  . Compile and test with many different config options, and combinations of  . Compile and test with many different config options, and combinations of
70    options:    options. The maint/ManyConfigTests script now encapsulates this testing.
71    
    * 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.  
   
72  . 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
73    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
74    other tests are not Perl-compatible (they use various special PCRE options).    other tests are not Perl-compatible (they use various special PCRE options).
75    
 . 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).  
   
76  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest
77    valgrind", though that takes quite a long time.    valgrind", though that takes quite a long time.
78    
79  . 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
80    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
81    pcretest is hardly a big problem.) To build with EF, use:    pcretest is hardly a big problem.) To build with EF, use:
82    
83      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.
84    
85    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
86    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.  
87    
88  . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,      EF_PROTECT_BELOW=1 <whatever>
89    LICENCE, NEWS (check date), NON-UNIX-USE, and README. Many of these won't  
90      because there have been problems with lookbehinds that looked too far.
91    
92    . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and
93      HAVE_BCOPY in config.h. You may see a number of "pcre_memmove defined but not
94      used" warnings for the modules in which there is no call to memmove(). These
95      can be ignored.
96    
97    . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,
98      LICENCE, NEWS (check date), NON-UNIX-USE, and README. Many of these won't
99    need changing, but over the long term things do change.    need changing, but over the long term things do change.
100    
101  . 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
102    that indicates a markup error.    that indicates a markup error.
103    
104    . When the release is built, test it on a number of different operating
105      systems if possible, and using different compilers as well. For example,
106      on Solaris it is helpful to test using Sun's cc compiler as a change from
107      gcc. Adding -xarch=v9 to the cc options does a 64-bit test, but it also
108      needs -S 64 for pcretest to increase the stack size for test 2.
109    
110    
111  Making a PCRE release  Making a PCRE release
112  ---------------------  ---------------------
113    
114  Run PrepareRelease and commit the files that it changes (by removing trailing  Run PrepareRelease and commit the files that it changes (by removing trailing
115  spaces). Then run "make dist" to create the tarballs and the zipball.  spaces). Then run "make distcheck" to create the tarballs and the zipball.
116    
117  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
118  webmaster@pcre.org and the mailing list.  webmaster@pcre.org and the mailing list.
# Line 131  Future ideas (wish list) Line 122  Future ideas (wish list)
122  ------------------------  ------------------------
123    
124  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
125  vary enormously in their usefulness and potential for implementation. Some are  vary enormously in their usefulness and potential for implementation. Some are
126  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;
127  others are relatively new.  others are relatively new.
128    
129  . Optimization  . Optimization
130    
131    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
132    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
133    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:
134    
135    * /((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
136      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}?
137      OTOH, this is pathological - the user could easily fix it.      OTOH, this is pathological - the user could easily fix it.
138    
139    * 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
140      to have little effect, and maybe makes things worse.      to have little effect, and maybe makes things worse.
141    
142    * "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
143      over the existing "required byte" (reqbyte) feature that just saves one      over the existing "required byte" (reqbyte) feature that just saves one
144      byte.      byte.
145    
146    * These probably need to go in study():    * These probably need to go in study():
147    
148      o Remember an initial string rather than just 1 char?      o Remember an initial string rather than just 1 char?
149    
150      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
151        earlier one if common to all alternatives.        earlier one if common to all alternatives.
152    
153      o Minimum length of subject needed.      o Minimum length of subject needed.
154    
155      o Friedl contains other ideas.      o Friedl contains other ideas.
156    
157  . 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-
158    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
159    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE
160    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
161    because I think it needs much more state to be remembered.    because I think it needs much more state to be remembered.
162    
163  . 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?
164    
165  . Unicode  . Unicode
166    
167    * 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
168      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
169      backward compatibility, for speed, and because it would be messy to      backward compatibility, for speed, and because it would be messy to
170      implement.      implement.
171    
172    * 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
173      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
174      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
175      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
176      don't think this is particularly trivial - and anyway, Unicode now has      don't think this is particularly trivial - and anyway, Unicode now has
177      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?
178    
179    * 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
180      UTF-16. However, since Unicode is moving beyond purely 16-bit characters,      UTF-16. However, since Unicode is moving beyond purely 16-bit characters,
181      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
182      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.
183    
184  . 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.
185    
186  . Line endings:  . Line endings:
187    
188    * 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
189      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.
190      If this is done, a suitable option for pcregrep is also required.      If this is done, a suitable option for pcregrep is also required.
191    
192  . 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.
193    This probably affects quite a few places in the code.    This probably affects quite a few places in the code.
194    
195  . 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.  
196    
197  . A feature to suspend a match via a callout was once requested.  . A feature to suspend a match via a callout was once requested.
198    
199  . Option to convert results into character offsets and character lengths.  . Option to convert results into character offsets and character lengths.
200    
201  . 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
202    the job of "head".    the job of "head".
203    
204  . 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,
205    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)
206    support --outputfile=name.    support --outputfile=name.
207    
208  . 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.
209    
210  . 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
211    needed to retain backward compatibility.    needed to retain backward compatibility.
212    
213  . Define a union for the results from pcre_fullinfo().  . Define a union for the results from pcre_fullinfo().
214    
215  . 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
216    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
217    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
218    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.
219    
220  . There are new (*PRUNE) facilities in Perl 5.10, some of which it might be  . There are new (*PRUNE) facilities in Perl 5.10, some of which it might be
221    relatively easy to implement.    relatively easy to implement.
222    
 . 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.  
   
223  . 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
224    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
225    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.
226    
227  . Should pcretest have some private locale data, to avoid relying on the  . Should pcretest have some private locale data, to avoid relying on the
228    available locales for the test data, since different OS have different ideas?    available locales for the test data, since different OS have different ideas?
229    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.
230    
231  . 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
232    them will of course slow it down.    them will of course slow it down.
233    
234  . 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
235    that is run only when the link size *is* 2; leave in some non-numbered    never wanted. This seems rather marginal.
236    debugging tests using the new /Z feature.  
237    . "Cut" as described in Jeffrey Friedl's book, p364: \v and \V. The definitions
238  . Stan Switzer's goto replacement for longjmp, which is apparently very slow on    aren't yet clear enough for me. \v flushes saved states so that no
239    OS-X. This is used when stack recursion is disabled. It would be worth doing    backtracking to anything earlier can happen; \V says "no more bumpalong", but
240    some timing tests on other OS.    does it fail the current match? As described in the book, these aren't really
241      "cut" as in Prolog, are they? NOTE: (a) PCRE once had "cut", but it was
242  . Someone suggested --disable-callout to save code space when callouts are    removed when atomic groups were introduced. (b) Perl 5.10 has some (*PRUNE)
243    never wanted. This seems rather marginal.    features --
244    
245  . Automate some of the testing before release into a script that compiles with  . These are the Perl 5.10 backtracking control features (all of which are
246    different options and runs the tests in each case.    described as "experimental" -- some of them "very experimental") that it
247      might be easy to add to PCRE. They all succeed when encountered, but act as
248  . How about distributing a fixed pcre_chartables.c file and abandoning the    follows when backtracking:
249    on-the-fly generation using dftables. This will make cross-compiling easier,  
250    and in any case, locales are going out of fashion.    (*PRUNE)  fail this match attempt, but still bumpalong
251      (*SKIP)   fail this match attempt, bumpalong to current match point
252      (*THEN)   fail this branch, try next branch at same level or fail if none
253      (*COMMIT) fail this match attempt, suppress bumpalong
254      (*FAIL)   fail and backtrack (same as (?!) and that can be optimized)
255      (*F)      synonym for (*FAIL)
256      (*ACCEPT) behave as if end of pattern reached ("very experimental")
257    
258      Some of these can have arguments (*PRUNE:NAME) but I'm not sure whether they
259      make sense in the PCRE context.
260    
261  Philip Hazel  Philip Hazel
262  Email local part: ph10  Email local part: ph10
263  Email domain: cam.ac.uk  Email domain: cam.ac.uk
264  Last updated: 12 March 2007  Last updated: 13 June 2007

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