4 files changed, 96 insertions, 17 deletions

diff --git a/src/pkg/bytes/bytes.go b/src/pkg/bytes/bytes.go
index 2739c5a3f..171fa3d1b 100644
--- a/src/pkg/bytes/bytes.go
+++ b/src/pkg/bytes/bytes.go
@@ -98,6 +98,16 @@ func Index(s, sep []byte) int {
 	return -1;
 }
 
+// IndexByte returns the index of the first instance of c in s, or -1 if c is not present in s.
+func IndexByte(s []byte, c byte) int {
+	for i, b := range s {
+		if b == c {
+			return i
+		}
+	}
+	return -1;
+}
+
 // LastIndex returns the index of the last instance of sep in s, or -1 if sep is not present in s.
 func LastIndex(s, sep []byte) int {
 	n := len(sep);
diff --git a/src/pkg/bytes/bytes_test.go b/src/pkg/bytes/bytes_test.go
index 1b197e1df..b7f826293 100644
--- a/src/pkg/bytes/bytes_test.go
+++ b/src/pkg/bytes/bytes_test.go
@@ -39,41 +39,83 @@ var faces = "☺☻☹"
 var commas = "1,2,3,4"
 var dots = "1....2....3....4"
 
-type CompareTest struct {
+type BinOpTest struct {
 	a	string;
 	b	string;
-	cmp	int;
+	i	int;
 }
 
-var comparetests = []CompareTest{
-	CompareTest{"", "", 0},
-	CompareTest{"a", "", 1},
-	CompareTest{"", "a", -1},
-	CompareTest{"abc", "abc", 0},
-	CompareTest{"ab", "abc", -1},
-	CompareTest{"abc", "ab", 1},
-	CompareTest{"x", "ab", 1},
-	CompareTest{"ab", "x", -1},
-	CompareTest{"x", "a", 1},
-	CompareTest{"b", "x", -1},
+var comparetests = []BinOpTest{
+	BinOpTest{"", "", 0},
+	BinOpTest{"a", "", 1},
+	BinOpTest{"", "a", -1},
+	BinOpTest{"abc", "abc", 0},
+	BinOpTest{"ab", "abc", -1},
+	BinOpTest{"abc", "ab", 1},
+	BinOpTest{"x", "ab", 1},
+	BinOpTest{"ab", "x", -1},
+	BinOpTest{"x", "a", 1},
+	BinOpTest{"b", "x", -1},
 }
 
 func TestCompare(t *testing.T) {
-	for i := 0; i < len(comparetests); i++ {
-		tt := comparetests[i];
+	for _, tt := range comparetests {
 		a := strings.Bytes(tt.a);
 		b := strings.Bytes(tt.b);
 		cmp := Compare(a, b);
 		eql := Equal(a, b);
-		if cmp != tt.cmp {
+		if cmp != tt.i {
 			t.Errorf(`Compare(%q, %q) = %v`, tt.a, tt.b, cmp)
 		}
-		if eql != (tt.cmp == 0) {
+		if eql != (tt.i == 0) {
 			t.Errorf(`Equal(%q, %q) = %v`, tt.a, tt.b, eql)
 		}
 	}
 }
 
+var indextests = []BinOpTest{
+	BinOpTest{"", "", 0},
+	BinOpTest{"a", "", 0},
+	BinOpTest{"", "a", -1},
+	BinOpTest{"abc", "abc", 0},
+	BinOpTest{"ab", "abc", -1},
+	BinOpTest{"abc", "bc", 1},
+	BinOpTest{"x", "ab", -1},
+	// one-byte tests for IndexByte
+	BinOpTest{"ab", "x", -1},
+	BinOpTest{"", "a", -1},
+	BinOpTest{"x", "a", -1},
+	BinOpTest{"x", "x", 0},
+	BinOpTest{"abc", "a", 0},
+	BinOpTest{"abc", "b", 1},
+	BinOpTest{"abc", "c", 2},
+	BinOpTest{"abc", "x", -1},
+}
+
+func TestIndex(t *testing.T) {
+	for _, tt := range indextests {
+		a := strings.Bytes(tt.a);
+		b := strings.Bytes(tt.b);
+		pos := Index(a, b);
+		if pos != tt.i {
+			t.Errorf(`Index(%q, %q) = %v`, tt.a, tt.b, pos)
+		}
+	}
+}
+
+func TestIndexByte(t *testing.T) {
+	for _, tt := range indextests {
+		if len(tt.b) != 1 {
+			continue
+		}
+		a := strings.Bytes(tt.a);
+		b := tt.b[0];
+		pos := IndexByte(a, b);
+		if pos != tt.i {
+			t.Errorf(`IndexByte(%q, '%c') = %v`, tt.a, b, pos)
+		}
+	}
+}
 
 type ExplodeTest struct {
 	s	string;
diff --git a/src/pkg/strings/strings.go b/src/pkg/strings/strings.go
index 7ccfc5ca8..fb3070a1a 100644
--- a/src/pkg/strings/strings.go
+++ b/src/pkg/strings/strings.go
@@ -56,6 +56,15 @@ func Index(s, sep string) int {
 		return 0
 	}
 	c := sep[0];
+	if n == 1 {
+		// special case worth making fast
+		for i := 0; i < len(s); i++ {
+			if s[i] == c {
+				return i
+			}
+		}
+		return -1;
+	}
 	for i := 0; i+n <= len(s); i++ {
 		if s[i] == c && (n == 1 || s[i:i+n] == sep) {
 			return i
@@ -71,6 +80,15 @@ func LastIndex(s, sep string) int {
 		return len(s)
 	}
 	c := sep[0];
+	if n == 1 {
+		// special case worth making fast
+		for i := len(s) - 1; i >= 0; i-- {
+			if s[i] == c {
+				return i
+			}
+		}
+		return -1;
+	}
 	for i := len(s) - n; i >= 0; i-- {
 		if s[i] == c && (n == 1 || s[i:i+n] == sep) {
 			return i
diff --git a/src/pkg/strings/strings_test.go b/src/pkg/strings/strings_test.go
index 0073f0d0e..1171db224 100644
--- a/src/pkg/strings/strings_test.go
+++ b/src/pkg/strings/strings_test.go
@@ -46,6 +46,14 @@ var indexTests = []IndexTest{
 	IndexTest{"foo", "", 0},
 	IndexTest{"foo", "o", 1},
 	IndexTest{"abcABCabc", "A", 3},
+	// cases with one byte strings - test special case in Index()
+	IndexTest{"", "a", -1},
+	IndexTest{"x", "a", -1},
+	IndexTest{"x", "x", 0},
+	IndexTest{"abc", "a", 0},
+	IndexTest{"abc", "b", 1},
+	IndexTest{"abc", "c", 2},
+	IndexTest{"abc", "x", -1},
 }
 
 var lastIndexTests = []IndexTest{
@@ -54,6 +62,7 @@ var lastIndexTests = []IndexTest{
 	IndexTest{"", "foo", -1},
 	IndexTest{"fo", "foo", -1},
 	IndexTest{"foo", "foo", 0},
+	IndexTest{"foo", "f", 0},
 	IndexTest{"oofofoofooo", "f", 7},
 	IndexTest{"oofofoofooo", "foo", 7},
 	IndexTest{"barfoobarfoo", "foo", 9},