trunk/doc/pcredemo.3

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/*************************************************
*           PCRE DEMONSTRATION PROGRAM           *
*************************************************/

/* This is a demonstration program to illustrate the most straightforward ways
of calling the PCRE regular expression library from a C program. See the
pcresample documentation for a short discussion ("man pcresample" if you have
the PCRE man pages installed).

In Unix-like environments, if PCRE is installed in your standard system
libraries, you should be able to compile this program using this command:

gcc -Wall pcredemo.c -lpcre -o pcredemo

If PCRE is not installed in a standard place, it is likely to be installed with
support for the pkg-config mechanism. If you have pkg-config, you can compile
this program using this command:

gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo

If you do not have pkg-config, you may have to use this:

gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \e
  -R/usr/local/lib -lpcre -o pcredemo

Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and
library files for PCRE are installed on your system. Only some operating
systems (e.g. Solaris) use the -R option.

Building under Windows:

If you want to statically link this program against a non-dll .a file, you must
define PCRE_STATIC before including pcre.h, otherwise the pcre_malloc() and
pcre_free() exported functions will be declared __declspec(dllimport), with
unwanted results. So in this environment, uncomment the following line. */

/* #define PCRE_STATIC */

#include <stdio.h>
#include <string.h>
#include <pcre.h>

#define OVECCOUNT 30    /* should be a multiple of 3 */


int main(int argc, char **argv)
{
pcre *re;
const char *error;
char *pattern;
char *subject;
unsigned char *name_table;
unsigned int option_bits;
int erroffset;
int find_all;
int crlf_is_newline;
int namecount;
int name_entry_size;
int ovector[OVECCOUNT];
int subject_length;
int rc, i;
int utf8;


/**************************************************************************
* First, sort out the command line. There is only one possible option at  *
* the moment, "-g" to request repeated matching to find all occurrences,  *
* like Perl's /g option. We set the variable find_all to a non-zero value *
* if the -g option is present. Apart from that, there must be exactly two *
* arguments.                                                              *
**************************************************************************/

find_all = 0;
for (i = 1; i < argc; i++)
  {
  if (strcmp(argv[i], "-g") == 0) find_all = 1;
    else break;
  }

/* After the options, we require exactly two arguments, which are the pattern,
and the subject string. */

if (argc - i != 2)
  {
  printf("Two arguments required: a regex and a subject string\en");
  return 1;
  }

pattern = argv[i];
subject = argv[i+1];
subject_length = (int)strlen(subject);


/*************************************************************************
* Now we are going to compile the regular expression pattern, and handle *
* and errors that are detected.                                          *
*************************************************************************/

re = pcre_compile(
  pattern,              /* the pattern */
  0,                    /* default options */
  &error,               /* for error message */
  &erroffset,           /* for error offset */
  NULL);                /* use default character tables */

/* Compilation failed: print the error message and exit */

if (re == NULL)
  {
  printf("PCRE compilation failed at offset %d: %s\en", erroffset, error);
  return 1;
  }


/*************************************************************************
* If the compilation succeeded, we call PCRE again, in order to do a     *
* pattern match against the subject string. This does just ONE match. If *
* further matching is needed, it will be done below.                     *
*************************************************************************/

rc = pcre_exec(
  re,                   /* the compiled pattern */
  NULL,                 /* no extra data - we didn't study the pattern */
  subject,              /* the subject string */
  subject_length,       /* the length of the subject */
  0,                    /* start at offset 0 in the subject */
  0,                    /* default options */
  ovector,              /* output vector for substring information */
  OVECCOUNT);           /* number of elements in the output vector */

/* Matching failed: handle error cases */

if (rc < 0)
  {
  switch(rc)
    {
    case PCRE_ERROR_NOMATCH: printf("No match\en"); break;
    /*
    Handle other special cases if you like
    */
    default: printf("Matching error %d\en", rc); break;
    }
  pcre_free(re);     /* Release memory used for the compiled pattern */
  return 1;
  }

/* Match succeded */

printf("\enMatch succeeded at offset %d\en", ovector[0]);


/*************************************************************************
* We have found the first match within the subject string. If the output *
* vector wasn't big enough, say so. Then output any substrings that were *
* captured.                                                              *
*************************************************************************/

/* The output vector wasn't big enough */

if (rc == 0)
  {
  rc = OVECCOUNT/3;
  printf("ovector only has room for %d captured substrings\en", rc - 1);
  }

/* Show substrings stored in the output vector by number. Obviously, in a real
application you might want to do things other than print them. */

for (i = 0; i < rc; i++)
  {
  char *substring_start = subject + ovector[2*i];
  int substring_length = ovector[2*i+1] - ovector[2*i];
  printf("%2d: %.*s\en", i, substring_length, substring_start);
  }


/**************************************************************************
* That concludes the basic part of this demonstration program. We have    *
* compiled a pattern, and performed a single match. The code that follows *
* shows first how to access named substrings, and then how to code for    *
* repeated matches on the same subject.                                   *
**************************************************************************/

/* See if there are any named substrings, and if so, show them by name. First
we have to extract the count of named parentheses from the pattern. */

(void)pcre_fullinfo(
  re,                   /* the compiled pattern */
  NULL,                 /* no extra data - we didn't study the pattern */
  PCRE_INFO_NAMECOUNT,  /* number of named substrings */
  &namecount);          /* where to put the answer */

if (namecount <= 0) printf("No named substrings\en"); else
  {
  unsigned char *tabptr;
  printf("Named substrings\en");

  /* Before we can access the substrings, we must extract the table for
  translating names to numbers, and the size of each entry in the table. */

  (void)pcre_fullinfo(
    re,                       /* the compiled pattern */
    NULL,                     /* no extra data - we didn't study the pattern */
    PCRE_INFO_NAMETABLE,      /* address of the table */
    &name_table);             /* where to put the answer */

  (void)pcre_fullinfo(
    re,                       /* the compiled pattern */
    NULL,                     /* no extra data - we didn't study the pattern */
    PCRE_INFO_NAMEENTRYSIZE,  /* size of each entry in the table */
    &name_entry_size);        /* where to put the answer */

  /* Now we can scan the table and, for each entry, print the number, the name,
  and the substring itself. */

  tabptr = name_table;
  for (i = 0; i < namecount; i++)
    {
    int n = (tabptr[0] << 8) | tabptr[1];
    printf("(%d) %*s: %.*s\en", n, name_entry_size - 3, tabptr + 2,
      ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
    tabptr += name_entry_size;
    }
  }


/*************************************************************************
* If the "-g" option was given on the command line, we want to continue  *
* to search for additional matches in the subject string, in a similar   *
* way to the /g option in Perl. This turns out to be trickier than you   *
* might think because of the possibility of matching an empty string.    *
* What happens is as follows:                                            *
*                                                                        *
* If the previous match was NOT for an empty string, we can just start   *
* the next match at the end of the previous one.                         *
*                                                                        *
* If the previous match WAS for an empty string, we can't do that, as it *
* would lead to an infinite loop. Instead, a special call of pcre_exec() *
* is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set.    *
* The first of these tells PCRE that an empty string at the start of the *
* subject is not a valid match; other possibilities must be tried. The   *
* second flag restricts PCRE to one match attempt at the initial string  *
* position. If this match succeeds, an alternative to the empty string   *
* match has been found, and we can print it and proceed round the loop,  *
* advancing by the length of whatever was found. If this match does not  *
* succeed, we still stay in the loop, advancing by just one character.   *
* In UTF-8 mode, which can be set by (*UTF8) in the pattern, this may be *
* more than one byte.                                                    *
*                                                                        *
* However, there is a complication concerned with newlines. When the     *
* newline convention is such that CRLF is a valid newline, we must       *
* advance by two characters rather than one. The newline convention can  *
* be set in the regex by (*CR), etc.; if not, we must find the default.  *
*************************************************************************/

if (!find_all)     /* Check for -g */
  {
  pcre_free(re);   /* Release the memory used for the compiled pattern */
  return 0;        /* Finish unless -g was given */
  }

/* Before running the loop, check for UTF-8 and whether CRLF is a valid newline
sequence. First, find the options with which the regex was compiled; extract
the UTF-8 state, and mask off all but the newline options. */

(void)pcre_fullinfo(re, NULL, PCRE_INFO_OPTIONS, &option_bits);
utf8 = option_bits & PCRE_UTF8;
option_bits &= PCRE_NEWLINE_CR|PCRE_NEWLINE_LF|PCRE_NEWLINE_CRLF|
               PCRE_NEWLINE_ANY|PCRE_NEWLINE_ANYCRLF;

/* If no newline options were set, find the default newline convention from the
build configuration. */

if (option_bits == 0)
  {
  int d;
  (void)pcre_config(PCRE_CONFIG_NEWLINE, &d);
  /* Note that these values are always the ASCII ones, even in
  EBCDIC environments. CR = 13, NL = 10. */
  option_bits = (d == 13)? PCRE_NEWLINE_CR :
          (d == 10)? PCRE_NEWLINE_LF :
          (d == (13<<8 | 10))? PCRE_NEWLINE_CRLF :
          (d == -2)? PCRE_NEWLINE_ANYCRLF :
          (d == -1)? PCRE_NEWLINE_ANY : 0;
  }

/* See if CRLF is a valid newline sequence. */

crlf_is_newline =
     option_bits == PCRE_NEWLINE_ANY ||
     option_bits == PCRE_NEWLINE_CRLF ||
     option_bits == PCRE_NEWLINE_ANYCRLF;

/* Loop for second and subsequent matches */

for (;;)
  {
  int options = 0;                 /* Normally no options */
  int start_offset = ovector[1];   /* Start at end of previous match */

  /* If the previous match was for an empty string, we are finished if we are
  at the end of the subject. Otherwise, arrange to run another match at the
  same point to see if a non-empty match can be found. */

  if (ovector[0] == ovector[1])
    {
    if (ovector[0] == subject_length) break;
    options = PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED;
    }

  /* Run the next matching operation */

  rc = pcre_exec(
    re,                   /* the compiled pattern */
    NULL,                 /* no extra data - we didn't study the pattern */
    subject,              /* the subject string */
    subject_length,       /* the length of the subject */
    start_offset,         /* starting offset in the subject */
    options,              /* options */
    ovector,              /* output vector for substring information */
    OVECCOUNT);           /* number of elements in the output vector */

  /* This time, a result of NOMATCH isn't an error. If the value in "options"
  is zero, it just means we have found all possible matches, so the loop ends.
  Otherwise, it means we have failed to find a non-empty-string match at a
  point where there was a previous empty-string match. In this case, we do what
  Perl does: advance the matching position by one character, and continue. We
  do this by setting the "end of previous match" offset, because that is picked
  up at the top of the loop as the point at which to start again.

  There are two complications: (a) When CRLF is a valid newline sequence, and
  the current position is just before it, advance by an extra byte. (b)
  Otherwise we must ensure that we skip an entire UTF-8 character if we are in
  UTF-8 mode. */

  if (rc == PCRE_ERROR_NOMATCH)
    {
    if (options == 0) break;                    /* All matches found */
    ovector[1] = start_offset + 1;              /* Advance one byte */
    if (crlf_is_newline &&                      /* If CRLF is newline & */
        start_offset < subject_length - 1 &&    /* we are at CRLF, */
        subject[start_offset] == '\er' &&
        subject[start_offset + 1] == '\en')
      ovector[1] += 1;                          /* Advance by one more. */
    else if (utf8)                              /* Otherwise, ensure we */
      {                                         /* advance a whole UTF-8 */
      while (ovector[1] < subject_length)       /* character. */
        {
        if ((subject[ovector[1]] & 0xc0) != 0x80) break;
        ovector[1] += 1;
        }
      }
    continue;    /* Go round the loop again */
    }

  /* Other matching errors are not recoverable. */

  if (rc < 0)
    {
    printf("Matching error %d\en", rc);
    pcre_free(re);    /* Release memory used for the compiled pattern */
    return 1;
    }

  /* Match succeded */

  printf("\enMatch succeeded again at offset %d\en", ovector[0]);

  /* The match succeeded, but the output vector wasn't big enough. */

  if (rc == 0)
    {
    rc = OVECCOUNT/3;
    printf("ovector only has room for %d captured substrings\en", rc - 1);
    }

  /* As before, show substrings stored in the output vector by number, and then
  also any named substrings. */

  for (i = 0; i < rc; i++)
    {
    char *substring_start = subject + ovector[2*i];
    int substring_length = ovector[2*i+1] - ovector[2*i];
    printf("%2d: %.*s\en", i, substring_length, substring_start);
    }

  if (namecount <= 0) printf("No named substrings\en"); else
    {
    unsigned char *tabptr = name_table;
    printf("Named substrings\en");
    for (i = 0; i < namecount; i++)
      {
      int n = (tabptr[0] << 8) | tabptr[1];
      printf("(%d) %*s: %.*s\en", n, name_entry_size - 3, tabptr + 2,
        ovector[2*n+1] - ovector[2*n], subject + ovector[2*n]);
      tabptr += name_entry_size;
      }
    }
  }      /* End of loop to find second and subsequent matches */

printf("\en");
pcre_free(re);       /* Release memory used for the compiled pattern */
return 0;
}

/* End of pcredemo.c */
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1	.\" Start example.
2	.de EX
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10	.\" End example.
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12	. ft \\n(mE
13	. fi
14	. hy \\n(HY
15	..
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17	.EX
18	/*************************************************
19	* PCRE DEMONSTRATION PROGRAM *
20	*************************************************/
21
22	/* This is a demonstration program to illustrate the most straightforward ways
23	of calling the PCRE regular expression library from a C program. See the
24	pcresample documentation for a short discussion ("man pcresample" if you have
25	the PCRE man pages installed).
26
27	In Unix-like environments, if PCRE is installed in your standard system
28	libraries, you should be able to compile this program using this command:
29
30	gcc -Wall pcredemo.c -lpcre -o pcredemo
31
32	If PCRE is not installed in a standard place, it is likely to be installed with
33	support for the pkg-config mechanism. If you have pkg-config, you can compile
34	this program using this command:
35
36	gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo
37
38	If you do not have pkg-config, you may have to use this:
39
40	gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \e
41	-R/usr/local/lib -lpcre -o pcredemo
42
43	Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and
44	library files for PCRE are installed on your system. Only some operating
45	systems (e.g. Solaris) use the -R option.
46
47	Building under Windows:
48
49	If you want to statically link this program against a non-dll .a file, you must
50	define PCRE_STATIC before including pcre.h, otherwise the pcre_malloc() and
51	pcre_free() exported functions will be declared __declspec(dllimport), with
52	unwanted results. So in this environment, uncomment the following line. */
53
54	/* #define PCRE_STATIC */
55
56	#include <stdio.h>
57	#include <string.h>
58	#include <pcre.h>
59
60	#define OVECCOUNT 30 /* should be a multiple of 3 */
61
62
63	int main(int argc, char **argv)
64	{
65	pcre *re;
66	const char *error;
67	char *pattern;
68	char *subject;
69	unsigned char *name_table;
70	unsigned int option_bits;
71	int erroffset;
72	int find_all;
73	int crlf_is_newline;
74	int namecount;
75	int name_entry_size;
76	int ovector[OVECCOUNT];
77	int subject_length;
78	int rc, i;
79	int utf8;
80
81
82	/**************************************************************************
83	* First, sort out the command line. There is only one possible option at *
84	* the moment, "-g" to request repeated matching to find all occurrences, *
85	* like Perl's /g option. We set the variable find_all to a non-zero value *
86	* if the -g option is present. Apart from that, there must be exactly two *
87	* arguments. *
88	**************************************************************************/
89
90	find_all = 0;
91	for (i = 1; i < argc; i++)
92	{
93	if (strcmp(argv[i], "-g") == 0) find_all = 1;
94	else break;
95	}
96
97	/* After the options, we require exactly two arguments, which are the pattern,
98	and the subject string. */
99
100	if (argc - i != 2)
101	{
102	printf("Two arguments required: a regex and a subject string\en");
103	return 1;
104	}
105
106	pattern = argv[i];
107	subject = argv[i+1];
108	subject_length = (int)strlen(subject);
109
110
111	/*************************************************************************
112	* Now we are going to compile the regular expression pattern, and handle *
113	* and errors that are detected. *
114	*************************************************************************/
115
116	re = pcre_compile(
117	pattern, /* the pattern */
118	0, /* default options */
119	&error, /* for error message */
120	&erroffset, /* for error offset */
121	NULL); /* use default character tables */
122
123	/* Compilation failed: print the error message and exit */
124
125	if (re == NULL)
126	{
127	printf("PCRE compilation failed at offset %d: %s\en", erroffset, error);
128	return 1;
129	}
130
131
132	/*************************************************************************
133	* If the compilation succeeded, we call PCRE again, in order to do a *
134	* pattern match against the subject string. This does just ONE match. If *
135	* further matching is needed, it will be done below. *
136	*************************************************************************/
137
138	rc = pcre_exec(
139	re, /* the compiled pattern */
140	NULL, /* no extra data - we didn't study the pattern */
141	subject, /* the subject string */
142	subject_length, /* the length of the subject */
143	0, /* start at offset 0 in the subject */
144	0, /* default options */
145	ovector, /* output vector for substring information */
146	OVECCOUNT); /* number of elements in the output vector */
147
148	/* Matching failed: handle error cases */
149
150	if (rc < 0)
151	{
152	switch(rc)
153	{
154	case PCRE_ERROR_NOMATCH: printf("No match\en"); break;
155	/*
156	Handle other special cases if you like
157	*/
158	default: printf("Matching error %d\en", rc); break;
159	}
160	pcre_free(re); /* Release memory used for the compiled pattern */
161	return 1;
162	}
163
164	/* Match succeded */
165
166	printf("\enMatch succeeded at offset %d\en", ovector[0]);
167
168
169	/*************************************************************************
170	* We have found the first match within the subject string. If the output *
171	* vector wasn't big enough, say so. Then output any substrings that were *
172	* captured. *
173	*************************************************************************/
174
175	/* The output vector wasn't big enough */
176
177	if (rc == 0)
178	{
179	rc = OVECCOUNT/3;
180	printf("ovector only has room for %d captured substrings\en", rc - 1);
181	}
182
183	/* Show substrings stored in the output vector by number. Obviously, in a real
184	application you might want to do things other than print them. */
185
186	for (i = 0; i < rc; i++)
187	{
188	char substring_start = subject + ovector[2i];
189	int substring_length = ovector[2i+1] - ovector[2i];
190	printf("%2d: %.*s\en", i, substring_length, substring_start);
191	}
192
193
194	/**************************************************************************
195	* That concludes the basic part of this demonstration program. We have *
196	* compiled a pattern, and performed a single match. The code that follows *
197	* shows first how to access named substrings, and then how to code for *
198	* repeated matches on the same subject. *
199	**************************************************************************/
200
201	/* See if there are any named substrings, and if so, show them by name. First
202	we have to extract the count of named parentheses from the pattern. */
203
204	(void)pcre_fullinfo(
205	re, /* the compiled pattern */
206	NULL, /* no extra data - we didn't study the pattern */
207	PCRE_INFO_NAMECOUNT, /* number of named substrings */
208	&namecount); /* where to put the answer */
209
210	if (namecount <= 0) printf("No named substrings\en"); else
211	{
212	unsigned char *tabptr;
213	printf("Named substrings\en");
214
215	/* Before we can access the substrings, we must extract the table for
216	translating names to numbers, and the size of each entry in the table. */
217
218	(void)pcre_fullinfo(
219	re, /* the compiled pattern */
220	NULL, /* no extra data - we didn't study the pattern */
221	PCRE_INFO_NAMETABLE, /* address of the table */
222	&name_table); /* where to put the answer */
223
224	(void)pcre_fullinfo(
225	re, /* the compiled pattern */
226	NULL, /* no extra data - we didn't study the pattern */
227	PCRE_INFO_NAMEENTRYSIZE, /* size of each entry in the table */
228	&name_entry_size); /* where to put the answer */
229
230	/* Now we can scan the table and, for each entry, print the number, the name,
231	and the substring itself. */
232
233	tabptr = name_table;
234	for (i = 0; i < namecount; i++)
235	{
236	int n = (tabptr[0] << 8) \| tabptr[1];
237	printf("(%d) %s: %.s\en", n, name_entry_size - 3, tabptr + 2,
238	ovector[2n+1] - ovector[2n], subject + ovector[2*n]);
239	tabptr += name_entry_size;
240	}
241	}
242
243
244	/*************************************************************************
245	* If the "-g" option was given on the command line, we want to continue *
246	* to search for additional matches in the subject string, in a similar *
247	* way to the /g option in Perl. This turns out to be trickier than you *
248	* might think because of the possibility of matching an empty string. *
249	* What happens is as follows: *
250	* *
251	* If the previous match was NOT for an empty string, we can just start *
252	* the next match at the end of the previous one. *
253	* *
254	* If the previous match WAS for an empty string, we can't do that, as it *
255	* would lead to an infinite loop. Instead, a special call of pcre_exec() *
256	* is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set. *
257	* The first of these tells PCRE that an empty string at the start of the *
258	* subject is not a valid match; other possibilities must be tried. The *
259	* second flag restricts PCRE to one match attempt at the initial string *
260	* position. If this match succeeds, an alternative to the empty string *
261	* match has been found, and we can print it and proceed round the loop, *
262	* advancing by the length of whatever was found. If this match does not *
263	* succeed, we still stay in the loop, advancing by just one character. *
264	* In UTF-8 mode, which can be set by (UTF8) in the pattern, this may be
265	* more than one byte. *
266	* *
267	* However, there is a complication concerned with newlines. When the *
268	* newline convention is such that CRLF is a valid newline, we must *
269	* advance by two characters rather than one. The newline convention can *
270	* be set in the regex by (CR), etc.; if not, we must find the default.
271	*************************************************************************/
272
273	if (!find_all) /* Check for -g */
274	{
275	pcre_free(re); /* Release the memory used for the compiled pattern */
276	return 0; /* Finish unless -g was given */
277	}
278
279	/* Before running the loop, check for UTF-8 and whether CRLF is a valid newline
280	sequence. First, find the options with which the regex was compiled; extract
281	the UTF-8 state, and mask off all but the newline options. */
282
283	(void)pcre_fullinfo(re, NULL, PCRE_INFO_OPTIONS, &option_bits);
284	utf8 = option_bits & PCRE_UTF8;
285	option_bits &= PCRE_NEWLINE_CR\|PCRE_NEWLINE_LF\|PCRE_NEWLINE_CRLF\|
286	PCRE_NEWLINE_ANY\|PCRE_NEWLINE_ANYCRLF;
287
288	/* If no newline options were set, find the default newline convention from the
289	build configuration. */
290
291	if (option_bits == 0)
292	{
293	int d;
294	(void)pcre_config(PCRE_CONFIG_NEWLINE, &d);
295	/* Note that these values are always the ASCII ones, even in
296	EBCDIC environments. CR = 13, NL = 10. */
297	option_bits = (d == 13)? PCRE_NEWLINE_CR :
298	(d == 10)? PCRE_NEWLINE_LF :
299	(d == (13<<8 \| 10))? PCRE_NEWLINE_CRLF :
300	(d == -2)? PCRE_NEWLINE_ANYCRLF :
301	(d == -1)? PCRE_NEWLINE_ANY : 0;
302	}
303
304	/* See if CRLF is a valid newline sequence. */
305
306	crlf_is_newline =
307	option_bits == PCRE_NEWLINE_ANY \|\|
308	option_bits == PCRE_NEWLINE_CRLF \|\|
309	option_bits == PCRE_NEWLINE_ANYCRLF;
310
311	/* Loop for second and subsequent matches */
312
313	for (;;)
314	{
315	int options = 0; /* Normally no options */
316	int start_offset = ovector[1]; /* Start at end of previous match */
317
318	/* If the previous match was for an empty string, we are finished if we are
319	at the end of the subject. Otherwise, arrange to run another match at the
320	same point to see if a non-empty match can be found. */
321
322	if (ovector[0] == ovector[1])
323	{
324	if (ovector[0] == subject_length) break;
325	options = PCRE_NOTEMPTY_ATSTART \| PCRE_ANCHORED;
326	}
327
328	/* Run the next matching operation */
329
330	rc = pcre_exec(
331	re, /* the compiled pattern */
332	NULL, /* no extra data - we didn't study the pattern */
333	subject, /* the subject string */
334	subject_length, /* the length of the subject */
335	start_offset, /* starting offset in the subject */
336	options, /* options */
337	ovector, /* output vector for substring information */
338	OVECCOUNT); /* number of elements in the output vector */
339
340	/* This time, a result of NOMATCH isn't an error. If the value in "options"
341	is zero, it just means we have found all possible matches, so the loop ends.
342	Otherwise, it means we have failed to find a non-empty-string match at a
343	point where there was a previous empty-string match. In this case, we do what
344	Perl does: advance the matching position by one character, and continue. We
345	do this by setting the "end of previous match" offset, because that is picked
346	up at the top of the loop as the point at which to start again.
347
348	There are two complications: (a) When CRLF is a valid newline sequence, and
349	the current position is just before it, advance by an extra byte. (b)
350	Otherwise we must ensure that we skip an entire UTF-8 character if we are in
351	UTF-8 mode. */
352
353	if (rc == PCRE_ERROR_NOMATCH)
354	{
355	if (options == 0) break; /* All matches found */
356	ovector[1] = start_offset + 1; /* Advance one byte */
357	if (crlf_is_newline && /* If CRLF is newline & */
358	start_offset < subject_length - 1 && /* we are at CRLF, */
359	subject[start_offset] == '\er' &&
360	subject[start_offset + 1] == '\en')
361	ovector[1] += 1; /* Advance by one more. */
362	else if (utf8) /* Otherwise, ensure we */
363	{ /* advance a whole UTF-8 */
364	while (ovector[1] < subject_length) /* character. */
365	{
366	if ((subject[ovector[1]] & 0xc0) != 0x80) break;
367	ovector[1] += 1;
368	}
369	}
370	continue; /* Go round the loop again */
371	}
372
373	/* Other matching errors are not recoverable. */
374
375	if (rc < 0)
376	{
377	printf("Matching error %d\en", rc);
378	pcre_free(re); /* Release memory used for the compiled pattern */
379	return 1;
380	}
381
382	/* Match succeded */
383
384	printf("\enMatch succeeded again at offset %d\en", ovector[0]);
385
386	/* The match succeeded, but the output vector wasn't big enough. */
387
388	if (rc == 0)
389	{
390	rc = OVECCOUNT/3;
391	printf("ovector only has room for %d captured substrings\en", rc - 1);
392	}
393
394	/* As before, show substrings stored in the output vector by number, and then
395	also any named substrings. */
396
397	for (i = 0; i < rc; i++)
398	{
399	char substring_start = subject + ovector[2i];
400	int substring_length = ovector[2i+1] - ovector[2i];
401	printf("%2d: %.*s\en", i, substring_length, substring_start);
402	}
403
404	if (namecount <= 0) printf("No named substrings\en"); else
405	{
406	unsigned char *tabptr = name_table;
407	printf("Named substrings\en");
408	for (i = 0; i < namecount; i++)
409	{
410	int n = (tabptr[0] << 8) \| tabptr[1];
411	printf("(%d) %s: %.s\en", n, name_entry_size - 3, tabptr + 2,
412	ovector[2n+1] - ovector[2n], subject + ovector[2*n]);
413	tabptr += name_entry_size;
414	}
415	}
416	} /* End of loop to find second and subsequent matches */
417
418	printf("\en");
419	pcre_free(re); /* Release memory used for the compiled pattern */
420	return 0;
421	}
422
423	/* End of pcredemo.c */
424	.EE