407 lines
15 KiB
C
407 lines
15 KiB
C
|
/*************************************************
|
||
|
|
* 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 \
|
||
|
|
-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\n");
|
||
|
|
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\n", 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\n"); break;
|
||
|
|
/*
|
||
|
|
Handle other special cases if you like
|
||
|
|
*/
|
||
|
|
default: printf("Matching error %d\n", rc); break;
|
||
|
|
}
|
||
|
|
pcre_free(re); /* Release memory used for the compiled pattern */
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Match succeded */
|
||
|
|
|
||
|
|
printf("\nMatch succeeded at offset %d\n", 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\n", 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\n", 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\n"); else
|
||
|
|
{
|
||
|
|
unsigned char *tabptr;
|
||
|
|
printf("Named substrings\n");
|
||
|
|
|
||
|
|
/* 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\n", 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] == '\r' &&
|
||
|
|
subject[start_offset + 1] == '\n')
|
||
|
|
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\n", rc);
|
||
|
|
pcre_free(re); /* Release memory used for the compiled pattern */
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Match succeded */
|
||
|
|
|
||
|
|
printf("\nMatch succeeded again at offset %d\n", 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\n", 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\n", i, substring_length, substring_start);
|
||
|
|
}
|
||
|
|
|
||
|
|
if (namecount <= 0) printf("No named substrings\n"); else
|
||
|
|
{
|
||
|
|
unsigned char *tabptr = name_table;
|
||
|
|
printf("Named substrings\n");
|
||
|
|
for (i = 0; i < namecount; i++)
|
||
|
|
{
|
||
|
|
int n = (tabptr[0] << 8) | tabptr[1];
|
||
|
|
printf("(%d) %*s: %.*s\n", 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("\n");
|
||
|
|
pcre_free(re); /* Release memory used for the compiled pattern */
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* End of pcredemo.c */
|