From: Rob Pike <r@golang.org>
Date: Tue, 7 Apr 2009 07:32:16 +0000 (-0700)
Subject: add error case in doc for Index. simplify code slightly.
X-Git-Tag: weekly.2009-11-06~1883
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=640f3f25dcd238bfc6b4fd99b1808071cfa12888;p=gostls13.git

add error case in doc for Index. simplify code slightly.

R=rsc
DELTA=5  (1 added, 0 deleted, 4 changed)
OCL=27148
CL=27151
---

diff --git a/src/lib/strings.go b/src/lib/strings.go
index 1acbed425e..06a923427a 100644
--- a/src/lib/strings.go
+++ b/src/lib/strings.go
@@ -37,14 +37,15 @@ func Count(s, sep string) int {
 	return n
 }
 
-// Index returns the index of the first instance of sep in s.
+// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
 func Index(s, sep string) int {
-	if sep == "" {
+	n := len(sep);
+	if n == 0 {
 		return 0
 	}
 	c := sep[0];
-	for i := 0; i+len(sep) <= len(s); i++ {
-		if s[i] == c && (len(sep) == 1 || s[i:i+len(sep)] == sep) {
+	for i := 0; i+n <= len(s); i++ {
+		if s[i] == c && (n == 1 || s[i:i+n] == sep) {
 			return i
 		}
 	}