Use dfa even in multibyte locales.

2 files changed, 13 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index 54bd8682..ddf4469a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2016-07-24         Norihiro Tanaka      <noritnk@kcn.ne.jp>
+
+	* re.c (research): Now that the dfa matcher correctly runs even
+	in multibyte locales, try it if even if need_start is true.
+	However, if start > 0, avoid dfa matcher, since it can't handle
+	the case where the search starts in the middle of a string.
+
 2016-07-23         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
 	* builtin.c (do_print): Improve logic for formatting
diff --git a/re.c b/re.c
index 0a156ffc..5049bca6 100644
--- a/re.c
+++ b/re.c
@@ -266,17 +266,17 @@ research(Regexp *rp, char *str, int start,
 		rp->pat.not_bol = 1;
 
 	/*
-	 * Always do dfa search if can; if it fails, then even if
-	 * need_start is true, we won't bother with the regex search.
+	 * Always do dfa search if can; if it fails, we won't bother
+	 * with the regex search.
 	 *
 	 * The dfa matcher doesn't have a no_bol flag, so don't bother
 	 * trying it in that case.
 	 *
-	 * 7/2008: Skip the dfa matcher if need_start. The dfa matcher
-	 * has bugs in certain multibyte cases and it's too difficult
-	 * to try to special case things.
+	 * 7/2016: The dfa matcher can't handle a case where searching
+	 * starts in the middle of a string, so don't bother trying it
+	 * in that case.
 	 */
-	if (rp->dfa && ! no_bol && ! need_start) {
+	if (rp->dfa && ! no_bol && start == 0) {
 		char save;
 		size_t count = 0;
 		struct dfa *superset = dfasuperset(rp->dfareg);