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revision 33 by nigel, Sat Feb 24 21:39:01 2007 UTC revision 37 by nigel, Sat Feb 24 21:39:09 2007 UTC
# Line 16  README file for PCRE (Perl-compatible re Line 16  README file for PCRE (Perl-compatible re
16  * possible to pass over a pointer to character tables built in the current    *  * possible to pass over a pointer to character tables built in the current    *
17  * locale by pcre_maketables(). To use the default tables, this new arguement  *  * locale by pcre_maketables(). To use the default tables, this new arguement  *
18  * should be passed as NULL.                                                   *  * should be passed as NULL.                                                   *
19    *                                                                             *
20    *           IMPORTANT FOR THOSE UPGRADING FROM VERSION 2.05                   *
21    *                                                                             *
22    * Yet another (and again I hope this really is the last) change has been made *
23    * to the API for the pcre_exec() function. An additional argument has been    *
24    * added to make it possible to start the match other than at the start of the *
25    * subject string. This is important if there are lookbehinds. The new man     *
26    * page has the details, but you just want to convert existing programs, all   *
27    * you need to do is to stick in a new fifth argument to pcre_exec(), with a   *
28    * value of zero. For example, change                                          *
29    *                                                                             *
30    *   pcre_exec(pattern, extra, subject, length, options, ovec, ovecsize)       *
31    * to                                                                          *
32    *   pcre_exec(pattern, extra, subject, length, 0, options, ovec, ovecsize)    *
33  *******************************************************************************  *******************************************************************************
34    
35    
36  The distribution should contain the following files:  The distribution should contain the following files:
37    
38    ChangeLog         log of changes to the code    ChangeLog         log of changes to the code
39    LICENCE           conditions for the use of PCRE    LICENCE           conditions for the use of PCRE
40    Makefile          for building PCRE    Makefile          for building PCRE in Unix systems
41    README            this file    README            this file
42    RunTest           a shell script for running tests    RunTest           a Unix shell script for running tests
43    Tech.Notes        notes on the encoding    Tech.Notes        notes on the encoding
44    pcre.3            man page for the functions    pcre.3            man page source for the functions
45    pcreposix.3       man page for the POSIX wrapper API    pcre.3.txt        plain text version
46      pcre.3.html       HTML version
47      pcreposix.3       man page source for the POSIX wrapper API
48      pcreposix.3.txt   plain text version
49      pcreposix.3.HTML  HTML version
50    dftables.c        auxiliary program for building chartables.c    dftables.c        auxiliary program for building chartables.c
51    get.c             )    get.c             )
52    maketables.c      )    maketables.c      )
# Line 38  The distribution should contain the foll Line 57  The distribution should contain the foll
57    pcreposix.h       header for the external POSIX wrapper API    pcreposix.h       header for the external POSIX wrapper API
58    internal.h        header for internal use    internal.h        header for internal use
59    pcretest.c        test program    pcretest.c        test program
60    pgrep.1           man page for pgrep    pgrep.1           man page source for pgrep
61      pgrep.1.txt       plain text version
62      pgrep.1.HTML      HTML version
63    pgrep.c           source of a grep utility that uses PCRE    pgrep.c           source of a grep utility that uses PCRE
64    perltest          Perl test program    perltest          Perl test program
65    testinput1        test data, compatible with Perl 5.004 and 5.005    testinput1        test data, compatible with Perl 5.004 and 5.005
66    testinput2        test data for error messages and non-Perl things    testinput2        test data for error messages and non-Perl things
67    testinput3        test data, compatible with Perl 5.005    testinput3        test data, compatible with Perl 5.005
68    testinput4        test data for locale-specific tests    testinput4        test data for locale-specific tests
69    testoutput1       test results corresponding to testinput    testoutput1       test results corresponding to testinput1
70    testoutput2       test results corresponding to testinput2    testoutput2       test results corresponding to testinput2
71    testoutput3       test results corresponding to testinput3    testoutput3       test results corresponding to testinput3
72    testoutput4       test results corresponding to testinput4    testoutput4       test results corresponding to testinput4
73    
74  To build PCRE, edit Makefile for your system (it is a fairly simple make file,  To build PCRE on a Unix system, first edit Makefile for your system. It is a
75  and there are some comments at the top) and then run it. It builds two  fairly simple make file, and there are some comments near the top, after the
76  libraries called libpcre.a and libpcreposix.a, a test program called pcretest,  text "On a Unix system". Then run "make". It builds two libraries called
77  and the pgrep command.  libpcre.a and libpcreposix.a, a test program called pcretest, and the pgrep
78    command. You can use "make install" to copy these, and the public header file
79  To test PCRE, run the RunTest script in the pcre directory. This runs pcretest  pcre.h, to appropriate live directories on your system. These installation
80  on each of the testinput files in turn, and compares the output with the  directories are defined at the top of the Makefile, and you should edit them if
81    necessary.
82    
83    For a non-Unix system, read the comments at the top of Makefile, which give
84    some hints on what needs to be done. PCRE has been compiled on Windows systems
85    and on Macintoshes, but I don't know the details as I don't use those systems.
86    It should be straightforward to build PCRE on any system that has a Standard C
87    compiler.
88    
89    To test PCRE, run the RunTest script in the pcre directory. This can also be
90    run by "make runtest". It runs the pcretest test program (which is documented
91    below) on each of the testinput files in turn, and compares the output with the
92  contents of the corresponding testoutput file. A file called testtry is used to  contents of the corresponding testoutput file. A file called testtry is used to
93  hold the output from pcretest (which is documented below).  hold the output from pcretest. To run pcretest on just one of the test files,
94    give its number as an argument to RunTest, for example:
 To run pcretest on just one of the test files, give its number as an argument  
 to RunTest, for example:  
95    
96    RunTest 3    RunTest 3
97    
98  The first and third test files can also be fed directly into the perltest  The first and third test files can also be fed directly into the perltest
99  program to check that Perl gives the same results. The third file requires the  script to check that Perl gives the same results. The third file requires the
100  additional features of release 5.005, which is why it is kept separate from the  additional features of release 5.005, which is why it is kept separate from the
101  main test input, which needs only Perl 5.004. In the long run, when 5.005 is  main test input, which needs only Perl 5.004. In the long run, when 5.005 is
102  widespread, these two test files may get amalgamated.  widespread, these two test files may get amalgamated.
# Line 88  output to say why. If running this test Line 118  output to say why. If running this test
118  in the comparison output, it means that locale is not available on your system,  in the comparison output, it means that locale is not available on your system,
119  despite being listed by "locale". This does not mean that PCRE is broken.  despite being listed by "locale". This does not mean that PCRE is broken.
120    
 To install PCRE, copy libpcre.a to any suitable library directory (e.g.  
 /usr/local/lib), pcre.h to any suitable include directory (e.g.  
 /usr/local/include), and pcre.3 to any suitable man directory (e.g.  
 /usr/local/man/man3).  
   
 To install the pgrep command, copy it to any suitable binary directory, (e.g.  
 /usr/local/bin) and pgrep.1 to any suitable man directory (e.g.  
 /usr/local/man/man1).  
   
121  PCRE has its own native API, but a set of "wrapper" functions that are based on  PCRE has its own native API, but a set of "wrapper" functions that are based on
122  the POSIX API are also supplied in the library libpcreposix.a. Note that this  the POSIX API are also supplied in the library libpcreposix.a. Note that this
123  just provides a POSIX calling interface to PCRE: the regular expressions  just provides a POSIX calling interface to PCRE: the regular expressions
# Line 112  Character tables Line 133  Character tables
133    
134  PCRE uses four tables for manipulating and identifying characters. The final  PCRE uses four tables for manipulating and identifying characters. The final
135  argument of the pcre_compile() function is a pointer to a block of memory  argument of the pcre_compile() function is a pointer to a block of memory
136  containing the concatenated tables. A call to pcre_maketables() is used to  containing the concatenated tables. A call to pcre_maketables() can be used to
137  generate a set of tables in the current locale. However, if the final argument  generate a set of tables in the current locale. If the final argument for
138  is passed as NULL, a set of default tables that is built into the binary is  pcre_compile() is passed as NULL, a set of default tables that is built into
139  used.  the binary is used.
140    
141  The source file called chartables.c contains the default set of tables. This is  The source file called chartables.c contains the default set of tables. This is
142  not supplied in the distribution, but is built by the program dftables  not supplied in the distribution, but is built by the program dftables
143  (compiled from dftables.c), which uses the ANSI C character handling functions  (compiled from dftables.c), which uses the ANSI C character handling functions
144  such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table  such as isalnum(), isalpha(), isupper(), islower(), etc. to build the table
145  sources. This means that the default C locale set your system will control the  sources. This means that the default C locale which is set for your system will
146  contents of the tables. You can change the default tables by editing  control the contents of these default tables. You can change the default tables
147  chartables.c and then re-building PCRE. If you do this, you should probably  by editing chartables.c and then re-building PCRE. If you do this, you should
148  also edit Makefile to ensure that the file doesn't ever get re-generated.  probably also edit Makefile to ensure that the file doesn't ever get
149    re-generated.
150    
151  The first two 256-byte tables provide lower casing and case flipping functions,  The first two 256-byte tables provide lower casing and case flipping functions,
152  respectively. The next table consists of three 32-byte bit maps which identify  respectively. The next table consists of three 32-byte bit maps which identify
# Line 178  example, Line 200  example,
200    
201    /abc/\    /abc/\
202    
203  then a backslash is added to the end of the pattern. This provides a way of  then a backslash is added to the end of the pattern. This is done to provide a
204  testing the error condition that arises if a pattern finishes with a backslash,  way of testing the error condition that arises if a pattern finishes with a
205  because  backslash, because
206    
207    /abc\/    /abc\/
208    
# Line 188  is interpreted as the first line of a pa Line 210  is interpreted as the first line of a pa
210  pcretest to read the next line as a continuation of the regular expression.  pcretest to read the next line as a continuation of the regular expression.
211    
212  The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,  The pattern may be followed by i, m, s, or x to set the PCRE_CASELESS,
213  PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. These  PCRE_MULTILINE, PCRE_DOTALL, or PCRE_EXTENDED options, respectively. For
214  options have the same effect as they do in Perl.  example:
215    
216  There are also some upper case options that do not match Perl options: /A, /E,    /caseless/i
 and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.  
217    
218  The /L option must be followed directly by the name of a locale, for example,  These modifier letters have the same effect as they do in Perl. There are
219    others which set PCRE options that do not correspond to anything in Perl: /A,
220    /E, and /X set PCRE_ANCHORED, PCRE_DOLLAR_ENDONLY, and PCRE_EXTRA respectively.
221    
222    Searching for all possible matches within each subject string can be requested
223    by the /g or /G modifier. The /g modifier behaves similarly to the way it does
224    in Perl. After finding a match, PCRE is called again to search the remainder of
225    the subject string. The difference between /g and /G is that the former uses
226    the start_offset argument to pcre_exec() to start searching at a new point
227    within the entire string, whereas the latter passes over a shortened substring.
228    This makes a difference to the matching process if the pattern begins with a
229    lookbehind assertion (including \b or \B).
230    
231    There are a number of other modifiers for controlling the way pcretest
232    operates.
233    
234    The /+ modifier requests that as well as outputting the substring that matched
235    the entire pattern, pcretest should in addition output the remainder of the
236    subject string. This is useful for tests where the subject contains multiple
237    copies of the same substring.
238    
239    The /L modifier must be followed directly by the name of a locale, for example,
240    
241    /pattern/Lfr    /pattern/Lfr
242    
243  For this reason, it must be the last option letter. The given locale is set,  For this reason, it must be the last modifier letter. The given locale is set,
244  pcre_maketables() is called to build a set of character tables for the locale,  pcre_maketables() is called to build a set of character tables for the locale,
245  and this is then passed to pcre_compile() when compiling the regular  and this is then passed to pcre_compile() when compiling the regular
246  expression. Without an /L option, NULL is passed as the tables pointer; that  expression. Without an /L modifier, NULL is passed as the tables pointer; that
247  is, /L applies only to the expression on which it appears.  is, /L applies only to the expression on which it appears.
248    
249  The /I option requests that pcretest output information about the compiled  The /I modifier requests that pcretest output information about the compiled
250  expression (whether it is anchored, has a fixed first character, and so on). It  expression (whether it is anchored, has a fixed first character, and so on). It
251  does this by calling pcre_info() after compiling an expression, and outputting  does this by calling pcre_info() after compiling an expression, and outputting
252  the information it gets back. If the pattern is studied, the results of that  the information it gets back. If the pattern is studied, the results of that
253  are also output.  are also output.
254    
255  The /D option is a PCRE debugging feature, which also assumes /I. It causes the  The /D modifier is a PCRE debugging feature, which also assumes /I. It causes
256  internal form of compiled regular expressions to be output after compilation.  the internal form of compiled regular expressions to be output after
257    compilation.
258    
259  The /S option causes pcre_study() to be called after the expression has been  The /S modifier causes pcre_study() to be called after the expression has been
260  compiled, and the results used when the expression is matched.  compiled, and the results used when the expression is matched.
261    
262  The /M option causes information about the size of memory block used to hold  The /M modifier causes the size of memory block used to hold the compiled
263  the compile pattern to be output.  pattern to be output.
264    
265  Finally, the /P option causes pcretest to call PCRE via the POSIX wrapper API  Finally, the /P modifier causes pcretest to call PCRE via the POSIX wrapper API
266  rather than its native API. When this is done, all other options except /i and  rather than its native API. When this is done, all other modifiers except /i,
267  /m are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is set if /m  /m, and /+ are ignored. REG_ICASE is set if /i is present, and REG_NEWLINE is
268  is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always, and  set if /m is present. The wrapper functions force PCRE_DOLLAR_ENDONLY always,
269  PCRE_DOTALL unless REG_NEWLINE is set.  and PCRE_DOTALL unless REG_NEWLINE is set.
270    
271  Before each data line is passed to pcre_exec(), leading and trailing whitespace  Before each data line is passed to pcre_exec(), leading and trailing whitespace
272  is removed, and it is then scanned for \ escapes. The following are recognized:  is removed, and it is then scanned for \ escapes. The following are recognized:
# Line 246  is removed, and it is then scanned for \ Line 289  is removed, and it is then scanned for \
289    \Gdd   call pcre_get_substring() for substring dd after a successful match    \Gdd   call pcre_get_substring() for substring dd after a successful match
290             (any decimal number less than 32)             (any decimal number less than 32)
291    \L     call pcre_get_substringlist() after a successful match    \L     call pcre_get_substringlist() after a successful match
292      \N     pass the PCRE_NOTEMPTY option to pcre_exec()
293    \Odd   set the size of the output vector passed to pcre_exec() to dd    \Odd   set the size of the output vector passed to pcre_exec() to dd
294             (any number of decimal digits)             (any number of decimal digits)
295    \Z     pass the PCRE_NOTEOL option to pcre_exec()    \Z     pass the PCRE_NOTEOL option to pcre_exec()
# Line 263  pcre_exec() returns, starting with numbe Line 307  pcre_exec() returns, starting with numbe
307  whole pattern. Here is an example of an interactive pcretest run.  whole pattern. Here is an example of an interactive pcretest run.
308    
309    $ pcretest    $ pcretest
310    Testing Perl-Compatible Regular Expressions    PCRE version 2.06 08-Jun-1999
   PCRE version 0.90 08-Sep-1997  
311    
312      re> /^abc(\d+)/      re> /^abc(\d+)/
313    data> abc123    data> abc123
314      0: abc123     0: abc123
315      1: 123     1: 123
316    data> xyz    data> xyz
317    No match    No match
318    
319    If the strings contain any non-printing characters, they are output as \0x
320    escapes. If the pattern has the /+ modifier, then the output for substring 0 is
321    followed by the the rest of the subject string, identified by "0+" like this:
322    
323        re> /cat/+
324      data> cataract
325       0: cat
326       0+ aract
327    
328    If the pattern has the /g or /G modifier, the results of successive matching
329    attempts are output in sequence, like this:
330    
331        re> /\Bi(\w\w)/g
332      data> Mississippi
333       0: iss
334       1: ss
335       0: iss
336       1: ss
337       0: ipp
338       1: pp
339    
340    "No match" is output only if the first match attempt fails.
341    
342  If any of \C, \G, or \L are present in a data line that is successfully  If any of \C, \G, or \L are present in a data line that is successfully
343  matched, the substrings extracted by the convenience functions are output with  matched, the substrings extracted by the convenience functions are output with
344  C, G, or L after the string number instead of a colon. This is in addition to  C, G, or L after the string number instead of a colon. This is in addition to
# Line 313  The perltest program Line 379  The perltest program
379    
380  The perltest program tests Perl's regular expressions; it has the same  The perltest program tests Perl's regular expressions; it has the same
381  specification as pcretest, and so can be given identical input, except that  specification as pcretest, and so can be given identical input, except that
382  input patterns can be followed only by Perl's lower case options. The contents  input patterns can be followed only by Perl's lower case modifiers. The
383  of testinput1 and testinput3 meet this condition.  contents of testinput1 and testinput3 meet this condition.
384    
385  The data lines are processed as Perl strings, so if they contain $ or @  The data lines are processed as Perl double-quoted strings, so if they contain
386  characters, these have to be escaped. For this reason, all such characters in  " \ $ or @ characters, these have to be escaped. For this reason, all such
387  the testinput file are escaped so that it can be used for perltest as well as  characters in testinput1 and testinput3 are escaped so that they can be used
388  for pcretest, and the special upper case options such as /A that pcretest  for perltest as well as for pcretest, and the special upper case modifiers such
389  recognizes are not used in this file. The output should be identical, apart  as /A that pcretest recognizes are not used in these files. The output should
390  from the initial identifying banner.  be identical, apart from the initial identifying banner.
391    
392  The testinput2 and testinput4 files are not suitable for feeding to Perltest,  The testinput2 and testinput4 files are not suitable for feeding to perltest,
393  since they do make use of the special upper case options and escapes that  since they do make use of the special upper case modifiers and escapes that
394  pcretest uses to test some features of PCRE. The first of these files also  pcretest uses to test some features of PCRE. The first of these files also
395  contains malformed regular expressions, in order to check that PCRE diagnoses  contains malformed regular expressions, in order to check that PCRE diagnoses
396  them correctly.  them correctly.
397    
398  Philip Hazel <ph10@cam.ac.uk>  Philip Hazel <ph10@cam.ac.uk>
399  April 1999  July 1999

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