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#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <assert.h>
#include <stdio.h>
#include "regex.h"
/*
To implement:
- ^
- $
- [...]
- [^...]
- *
*/
range_t*_regexp_match(char *whole_regex, char *regex, char *line, bool caret, bool dollar, size_t index, size_t start, size_t len) {
if ((regex[0] == '\0' && line[0] == '\0') || (regex[0] == '\0' && !dollar)) {
range_t *result = malloc(sizeof(range_t));
*result = (range_t){.start=start, .end=len + start};
return result;
}
else if (regex[0] == '\0') {
return NULL;
}
else if (regex[1] == '*') {
if (regex[0] == line[0] && line[0] != '\0') {
range_t *end = _regexp_match(whole_regex, regex + 2, line + 1, caret, dollar, index + 1, start, len + 1);
if (end) {
return end;
}
range_t *include = _regexp_match(whole_regex, regex, line + 1, caret, dollar, index + 1, start, len + 1);
if (include) {
return include;
}
}
if (!caret && line[0] != '\0') {
range_t *restart = _regexp_match(whole_regex, whole_regex, line + 1, caret, dollar, index + 1, index + 1, 0);
if (restart) {
return restart;
}
}
range_t *skip = _regexp_match(whole_regex, regex + 2, line, caret, dollar, index, start, len);
if (skip) {
return skip;
}
return NULL;
}
else if (regex[0] == line[0]) {
return _regexp_match(whole_regex, regex + 1, line + 1, caret, dollar, index + 1, start, len + 1);
}
else if (!caret && line[0] != '\0') {
return _regexp_match(whole_regex, whole_regex, line + 1, caret, dollar, index + 1, index + 1, 0);
}
else {
return NULL;
}
}
range_t *regexp_match(char *regex, char *line) {
bool caret = false;
if (regex[0] == '^') {
caret = true;
regex += 1;
}
bool dollar = false;
if (regex[strlen(regex) - 1] == '$') {
dollar = true;
regex[strlen(regex) - 1] = '\0';
}
assert(line[0] != '*');
return _regexp_match(regex, regex, line, caret, dollar, 0, 0, 0);
}