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/*
* This example code shows how to iterate over all regex matches in a file,
* emit the match location and print the contents of a capturing group.
*/
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include "rure.h"
int main() {
/* Open a file and mmap it. */
int fd = open("sherlock.txt", O_RDONLY);
if (fd == -1) {
perror("failed to open sherlock.txt");
exit(1);
}
struct stat status;
if (fstat(fd, &status) == -1) {
perror("failed to stat sherlock.txt");
exit(1);
}
if ((uintmax_t)status.st_size > SIZE_MAX) {
perror("file too big");
exit(1);
}
if (status.st_size == 0) {
perror("file empty");
exit(1);
}
size_t sherlock_len = (size_t)status.st_size;
const uint8_t *sherlock = (const uint8_t *)mmap(
NULL, status.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (sherlock == MAP_FAILED) {
perror("could not mmap file");
exit(1);
}
/*
* Compile the regular expression. A more convenient routine,
* rure_compile_must, is also available, which will abort the process if
* and print an error message to stderr if the regex compilation fails.
* We show the full gory details here as an example.
*/
const char *pattern = "(\\w+)\\s+Holmes";
size_t pattern_len = strlen(pattern);
rure_error *err = rure_error_new();
rure *re = rure_compile((const uint8_t *)pattern, pattern_len,
RURE_FLAG_UNICODE | RURE_FLAG_CASEI, NULL, err);
if (NULL == re) {
/* A null regex means compilation failed and an error exists. */
printf("compilation of %s failed: %s\n",
pattern, rure_error_message(err));
rure_error_free(err);
munmap((char*)sherlock, sherlock_len);
exit(1);
}
rure_error_free(err);
/*
* Create an iterator to find all successive non-overlapping matches.
* For each match, we extract the location of the capturing group.
*/
rure_match group0 = {0};
rure_match group1 = {0};
rure_captures *caps = rure_captures_new(re);
rure_iter *it = rure_iter_new(re);
while (rure_iter_next_captures(it, sherlock, sherlock_len, caps)) {
/*
* Get the location of the full match and the capturing group.
* We know that both accesses are successful since the body of the
* loop only executes if there is a match and both capture groups
* must match in order for the entire regex to match.
*
* N.B. The zeroth group corresponds to the full match of the regex.
*/
rure_captures_at(caps, 0, &group0);
rure_captures_at(caps, 1, &group1);
printf("%.*s (match at: %zu, %zu)\n",
(int)(group1.end - group1.start),
sherlock + group1.start,
group0.start, group0.end);
}
/* Free all our resources. */
munmap((char*)sherlock, sherlock_len);
rure_captures_free(caps);
rure_iter_free(it);
rure_free(re);
return 0;
}