strings: Add ContainsAny and ContainsRune to correspond to IndexAny etc.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5430046

src/pkg/strings/strings.go

@@ -64,7 +64,17 @@ func Count(s, sep string) int {
 
 // Contains returns true if substr is within s.
 func Contains(s, substr string) bool {
-	return Index(s, substr) != -1
+	return Index(s, substr) >= 0
+}
+
+// ContainsAny returns true if any Unicode code points in chars are within s.
+func ContainsAny(s, chars string) bool {
+	return IndexAny(s, chars) >= 0
+}
+
+// ContainsRune returns true if the Unicode code point r is within s.
+func ContainsRune(s string, r rune) bool {
+	return IndexRune(s, r) >= 0
 }
 
 // Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
@@ -269,7 +279,7 @@ func FieldsFunc(s string, f func(rune) bool) []string {
 			fieldStart = i
 		}
 	}
-	if fieldStart != -1 { // Last field might end at EOF.
+	if fieldStart >= 0 { // Last field might end at EOF.
 		a[na] = s[fieldStart:]
 	}
 	return a
@@ -512,7 +522,7 @@ func lastIndexFunc(s string, f func(rune) bool, truth bool) int {
 }
 
 func makeCutsetFunc(cutset string) func(rune) bool {
-	return func(r rune) bool { return IndexRune(cutset, r) != -1 }
+	return func(r rune) bool { return IndexRune(cutset, r) >= 0 }
 }
 
 // Trim returns a slice of the string s with all leading and

src/pkg/strings/strings_test.go

@@ -908,6 +908,56 @@ func TestContains(t *testing.T) {
 	}
 }
 
+var ContainsAnyTests = []struct {
+	str, substr string
+	expected    bool
+}{
+	{"", "", false},
+	{"", "a", false},
+	{"", "abc", false},
+	{"a", "", false},
+	{"a", "a", true},
+	{"aaa", "a", true},
+	{"abc", "xyz", false},
+	{"abc", "xcz", true},
+	{"a☺b☻c☹d", "uvw☻xyz", true},
+	{"aRegExp*", ".(|)*+?^$[]", true},
+	{dots + dots + dots, " ", false},
+}
+
+func TestContainsAny(t *testing.T) {
+	for _, ct := range ContainsAnyTests {
+		if ContainsAny(ct.str, ct.substr) != ct.expected {
+			t.Errorf("ContainsAny(%s, %s) = %v, want %v",
+				ct.str, ct.substr, !ct.expected, ct.expected)
+		}
+	}
+}
+
+var ContainsRuneTests = []struct {
+	str      string
+	r        rune
+	expected bool
+}{
+	{"", 'a', false},
+	{"a", 'a', true},
+	{"aaa", 'a', true},
+	{"abc", 'y', false},
+	{"abc", 'c', true},
+	{"a☺b☻c☹d", 'x', false},
+	{"a☺b☻c☹d", '☻', true},
+	{"aRegExp*", '*', true},
+}
+
+func TestContainsRune(t *testing.T) {
+	for _, ct := range ContainsRuneTests {
+		if ContainsRune(ct.str, ct.r) != ct.expected {
+			t.Errorf("ContainsRune(%s, %s) = %v, want %v",
+				ct.str, ct.r, !ct.expected, ct.expected)
+		}
+	}
+}
+
 var EqualFoldTests = []struct {
 	s, t string
 	out  bool