gri3-wm/src/regex.c

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/*
* vim:ts=4:sw=4:expandtab
*
* i3 - an improved dynamic tiling window manager
* © 2009-2011 Michael Stapelberg and contributors (see also: LICENSE)
*
* regex.c: Interface to libPCRE (perl compatible regular expressions).
*
*/
#include "all.h"
/*
* Creates a new 'regex' struct containing the given pattern and a PCRE
* compiled regular expression. Also, calls pcre_study because this regex will
* most likely be used often (like for every new window and on every relevant
* property change of existing windows).
*
* Returns NULL if the pattern could not be compiled into a regular expression
* (and ELOGs an appropriate error message).
*
*/
struct regex *regex_new(const char *pattern) {
const char *error;
int errorcode, offset;
struct regex *re = scalloc(sizeof(struct regex));
re->pattern = sstrdup(pattern);
int options = PCRE_UTF8;
#ifdef PCRE_HAS_UCP
/* We use PCRE_UCP so that \B, \b, \D, \d, \S, \s, \W, \w and some POSIX
* character classes play nicely with Unicode */
options |= PCRE_UCP;
#endif
while (!(re->regex = pcre_compile2(pattern, options, &errorcode, &error, &offset, NULL))) {
/* If the error is that PCRE was not compiled with UTF-8 support we
* disable it and try again */
if (errorcode == 32) {
options &= ~PCRE_UTF8;
continue;
}
ELOG("PCRE regular expression compilation failed at %d: %s\n",
offset, error);
return NULL;
}
re->extra = pcre_study(re->regex, 0, &error);
/* If an error happened, we print the error message, but continue.
* Studying the regular expression leads to faster matching, but its not
* absolutely necessary. */
if (error) {
ELOG("PCRE regular expression studying failed: %s\n", error);
}
return re;
}
/*
* Frees the given regular expression. It must not be used afterwards!
*
*/
void regex_free(struct regex *regex) {
if (!regex)
return;
FREE(regex->pattern);
FREE(regex->regex);
FREE(regex->extra);
}
/*
* Checks if the given regular expression matches the given input and returns
* true if it does. In either case, it logs the outcome using LOG(), so it will
* be visible without any debug loglevel.
*
*/
bool regex_matches(struct regex *regex, const char *input) {
int rc;
/* We use strlen() because pcre_exec() expects the length of the input
* string in bytes */
if ((rc = pcre_exec(regex->regex, regex->extra, input, strlen(input), 0, 0, NULL, 0)) == 0) {
LOG("Regular expression \"%s\" matches \"%s\"\n",
regex->pattern, input);
return true;
}
if (rc == PCRE_ERROR_NOMATCH) {
LOG("Regular expression \"%s\" does not match \"%s\"\n",
regex->pattern, input);
return false;
}
ELOG("PCRE error %d while trying to use regular expression \"%s\" on input \"%s\", see pcreapi(3)\n",
rc, regex->pattern, input);
return false;
}