/[pcre]/code/trunk/pcredemo.c
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revision 315 by ph10, Fri Jan 25 17:23:16 2008 UTC revision 566 by ph10, Wed Nov 3 18:32:55 2010 UTC
# Line 4  Line 4 
4    
5  /* This is a demonstration program to illustrate the most straightforward ways  /* This is a demonstration program to illustrate the most straightforward ways
6  of calling the PCRE regular expression library from a C program. See the  of calling the PCRE regular expression library from a C program. See the
7  pcresample documentation for a short discussion ("man pcresample" if you have  pcresample documentation for a short discussion ("man pcresample" if you have
8  the PCRE man pages installed).  the PCRE man pages installed).
9    
10  In Unix-like environments, compile this program thuswise:  In Unix-like environments, if PCRE is installed in your standard system
11    libraries, you should be able to compile this program using this command:
12    
13    gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \  gcc -Wall pcredemo.c -lpcre -o pcredemo
14      -R/usr/local/lib -lpcre  
15    If PCRE is not installed in a standard place, it is likely to be installed with
16    support for the pkg-config mechanism. If you have pkg-config, you can compile
17    this program using this command:
18    
19    gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo
20    
21    If you do not have pkg-config, you may have to use this:
22    
23    gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \
24      -R/usr/local/lib -lpcre -o pcredemo
25    
26  Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and  Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and
27  library files for PCRE are installed on your system. You don't need -I and -L  library files for PCRE are installed on your system. Only some operating
 if PCRE is installed in the standard system libraries. Only some operating  
28  systems (e.g. Solaris) use the -R option.  systems (e.g. Solaris) use the -R option.
29    
30  Building under Windows:  Building under Windows:
# Line 40  const char *error; Line 50  const char *error;
50  char *pattern;  char *pattern;
51  char *subject;  char *subject;
52  unsigned char *name_table;  unsigned char *name_table;
53    unsigned int option_bits;
54  int erroffset;  int erroffset;
55  int find_all;  int find_all;
56    int crlf_is_newline;
57  int namecount;  int namecount;
58  int name_entry_size;  int name_entry_size;
59  int ovector[OVECCOUNT];  int ovector[OVECCOUNT];
60  int subject_length;  int subject_length;
61  int rc, i;  int rc, i;
62    int utf8;
63    
64    
65  /**************************************************************************  /**************************************************************************
# Line 223  if (namecount <= 0) printf("No named sub Line 236  if (namecount <= 0) printf("No named sub
236  *                                                                        *  *                                                                        *
237  * If the previous match WAS for an empty string, we can't do that, as it *  * If the previous match WAS for an empty string, we can't do that, as it *
238  * would lead to an infinite loop. Instead, a special call of pcre_exec() *  * would lead to an infinite loop. Instead, a special call of pcre_exec() *
239  * is made with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set. The first  *  * is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set.    *
240  * of these tells PCRE that an empty string is not a valid match; other   *  * The first of these tells PCRE that an empty string at the start of the *
241  * possibilities must be tried. The second flag restricts PCRE to one     *  * subject is not a valid match; other possibilities must be tried. The   *
242  * match attempt at the initial string position. If this match succeeds,  *  * second flag restricts PCRE to one match attempt at the initial string  *
243  * an alternative to the empty string match has been found, and we can    *  * position. If this match succeeds, an alternative to the empty string   *
244  * proceed round the loop.                                                *  * match has been found, and we can print it and proceed round the loop,  *
245    * advancing by the length of whatever was found. If this match does not  *
246    * succeed, we still stay in the loop, advancing by just one character.   *
247    * In UTF-8 mode, which can be set by (*UTF8) in the pattern, this may be *
248    * more than one byte.                                                    *
249    *                                                                        *
250    * However, there is a complication concerned with newlines. When the     *
251    * newline convention is such that CRLF is a valid newline, we want must  *
252    * advance by two characters rather than one. The newline convention can  *
253    * be set in the regex by (*CR), etc.; if not, we must find the default.  *
254  *************************************************************************/  *************************************************************************/
255    
256  if (!find_all)  if (!find_all)     /* Check for -g */
257    {    {
258    pcre_free(re);   /* Release the memory used for the compiled pattern */    pcre_free(re);   /* Release the memory used for the compiled pattern */
259    return 0;        /* Finish unless -g was given */    return 0;        /* Finish unless -g was given */
260    }    }
261    
262    /* Before running the loop, check for UTF-8 and whether CRLF is a valid newline
263    sequence. First, find the options with which the regex was compiled; extract
264    the UTF-8 state, and mask off all but the newline options. */
265    
266    (void)pcre_fullinfo(re, NULL, PCRE_INFO_OPTIONS, &option_bits);
267    utf8 = option_bits & PCRE_UTF8;
268    option_bits &= PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|PCRE_NEWLINE_CRLF|
269                   PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF;
270    
271    /* If no newline options were set, find the default newline convention from the
272    build configuration. */
273    
274    if (option_bits == 0)
275      {
276      int d;
277      (void)pcre_config(PCRE_CONFIG_NEWLINE, &d);
278      /* Note that these values are always the ASCII ones, even in
279      EBCDIC environments. CR = 13, NL = 10. */
280      option_bits = (d == 13)? PCRE_NEWLINE_CR :
281              (d == 10)? PCRE_NEWLINE_LF :
282              (d == (13<<8 | 10))? PCRE_NEWLINE_CRLF :
283              (d == -2)? PCRE_NEWLINE_ANYCRLF :
284              (d == -1)? PCRE_NEWLINE_ANY : 0;
285      }
286    
287    /* See if CRLF is a valid newline sequence. */
288    
289    crlf_is_newline =
290         option_bits == PCRE_NEWLINE_ANY ||
291         option_bits == PCRE_NEWLINE_CRLF ||
292         option_bits == PCRE_NEWLINE_ANYCRLF;
293    
294  /* Loop for second and subsequent matches */  /* Loop for second and subsequent matches */
295    
296  for (;;)  for (;;)
# Line 251  for (;;) Line 305  for (;;)
305    if (ovector[0] == ovector[1])    if (ovector[0] == ovector[1])
306      {      {
307      if (ovector[0] == subject_length) break;      if (ovector[0] == subject_length) break;
308      options = PCRE_NOTEMPTY | PCRE_ANCHORED;      options = PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED;
309      }      }
310    
311    /* Run the next matching operation */    /* Run the next matching operation */
# Line 270  for (;;) Line 324  for (;;)
324    is zero, it just means we have found all possible matches, so the loop ends.    is zero, it just means we have found all possible matches, so the loop ends.
325    Otherwise, it means we have failed to find a non-empty-string match at a    Otherwise, it means we have failed to find a non-empty-string match at a
326    point where there was a previous empty-string match. In this case, we do what    point where there was a previous empty-string match. In this case, we do what
327    Perl does: advance the matching position by one, and continue. We do this by    Perl does: advance the matching position by one character, and continue. We
328    setting the "end of previous match" offset, because that is picked up at the    do this by setting the "end of previous match" offset, because that is picked
329    top of the loop as the point at which to start again. */    up at the top of the loop as the point at which to start again.
330    
331      There are two complications: (a) When CRLF is a valid newline sequence, and
332      the current position is just before it, advance by an extra byte. (b)
333      Otherwise we must ensure that we skip an entire UTF-8 character if we are in
334      UTF-8 mode. */
335    
336    if (rc == PCRE_ERROR_NOMATCH)    if (rc == PCRE_ERROR_NOMATCH)
337      {      {
338      if (options == 0) break;      if (options == 0) break;                    /* All matches found */
339      ovector[1] = start_offset + 1;      ovector[1] = start_offset + 1;              /* Advance one byte */
340        if (crlf_is_newline &&                      /* If CRLF is newline & */
341            start_offset < subject_length - 1 &&    /* we are at CRLF, */
342            subject[start_offset] == '\r' &&
343            subject[start_offset + 1] == '\n')
344          ovector[1] += 1;                          /* Advance by one more. */
345        else if (utf8)                              /* Otherwise, ensure we */
346          {                                         /* advance a whole UTF-8 */
347          while (ovector[1] < subject_length)       /* character. */
348            {
349            if ((subject[ovector[1]] & 0xc0) != 0x80) break;
350            ovector[1] += 1;
351            }
352          }
353      continue;    /* Go round the loop again */      continue;    /* Go round the loop again */
354      }      }
355    

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