es: add a function for extracting a specified group in the pattern matching

Signed-off-by: Masatake YAMATO <[email protected]>

Author: masatake

dsl/es.c

@@ -1352,6 +1352,29 @@ es_regex_exec    (const EsObject* regex,
 					0, NULL, 0)? es_false: es_true;
 }
 
+EsObject*
+es_regex_exec_extract_match_new (const EsObject* regex,
+								 const EsObject* str,
+								 unsigned int group)
+{
+	EsObject *r;
+	regmatch_t *pmatch = calloc(group + 1, sizeof(regmatch_t));
+	if (!pmatch)
+		return ES_ERROR_MEMORY;
+
+	const char *s = es_string_get (str);
+	if (regexec(((EsRegex*)regex)->code, s, group + 1, pmatch, 0))
+		r = es_false;
+	else
+		r = pmatch[group].rm_so == -1
+			? es_nil:
+			es_string_newL(s + pmatch[group].rm_so,
+						   pmatch[group].rm_eo - pmatch[group].rm_so);
+
+	free (pmatch);
+	return r;
+}
+
 /*
  * Error
  */

dsl/es.h

@@ -159,6 +159,12 @@ int          es_regex_p       (const EsObject* object);
 EsObject*    es_regex_exec    (const EsObject* regex,
 							   const EsObject* str);
 
+/* Return #f if unmatched.
+ * Retrun NIL is the associate group is not in REGEX. */
+EsObject*    es_regex_exec_extract_match_new (const EsObject* regex,
+											  const EsObject* str,
+											  unsigned int group);
+
 /*
  * Foreign pointer
  */