strings: Contains

Tiny helper to avoid strings.Index(s, sub) != -1

R=rsc, r2, r
CC=golang-dev
https://golang.org/cl/2265044

src/pkg/exec/lp_unix.go

@@ -25,7 +25,7 @@ func LookPath(file string) (string, os.Error) {
 	// (only bypass the path if file begins with / or ./ or ../)
 	// but that would not match all the Unix shells.
 
-	if strings.Index(file, "/") >= 0 {
+	if strings.Contains(file, "/") {
 		if canExec(file) {
 			return file, nil
 		}

src/pkg/exec/lp_windows.go

@@ -45,7 +45,7 @@ func LookPath(file string) (string, os.Error) {
 			}
 		}
 	}
-	if strings.Index(file, `\`) >= 0 || strings.Index(file, `/`) >= 0 {
+	if strings.Contains(file, `\`) || strings.Contains(file, `/`) {
 		if f, ok := canExec(file, exts); ok {
 			return f, nil
 		}

src/pkg/fmt/fmt_test.go

@@ -382,7 +382,7 @@ var fmttests = []fmtTest{
 func TestSprintf(t *testing.T) {
 	for _, tt := range fmttests {
 		s := Sprintf(tt.fmt, tt.val)
-		if i := strings.Index(s, "0x"); i >= 0 && strings.Index(tt.out, "PTR") >= 0 {
+		if i := strings.Index(s, "0x"); i >= 0 && strings.Contains(tt.out, "PTR") {
 			j := i + 2
 			for ; j < len(s); j++ {
 				c := s[j]

src/pkg/http/request.go

@@ -299,7 +299,7 @@ func readKeyValue(b *bufio.Reader) (key, value string, err os.Error) {
 	}
 
 	key = string(line[0:i])
-	if strings.Index(key, " ") >= 0 {
+	if strings.Contains(key, " ") {
 		// Key field has space - no good.
 		goto Malformed
 	}
@@ -689,5 +689,5 @@ func (r *Request) wantsHttp10KeepAlive() bool {
 	if !exists {
 		return false
 	}
-	return strings.Index(strings.ToLower(value), "keep-alive") != -1
+	return strings.Contains(strings.ToLower(value), "keep-alive")
 }

src/pkg/http/server.go

@@ -317,9 +317,9 @@ func errorKludge(w *response) {
 	// Is it a broken browser?
 	var msg string
 	switch agent := w.req.UserAgent; {
-	case strings.Index(agent, "MSIE") >= 0:
+	case strings.Contains(agent, "MSIE"):
 		msg = "Internet Explorer"
-	case strings.Index(agent, "Chrome/") >= 0:
+	case strings.Contains(agent, "Chrome/"):
 		msg = "Chrome"
 	default:
 		return

src/pkg/http/transfer.go

@@ -340,7 +340,7 @@ func fixLength(status int, requestMethod string, header map[string]string, te []
 	// Logic based on media type. The purpose of the following code is just
 	// to detect whether the unsupported "multipart/byteranges" is being
 	// used. A proper Content-Type parser is needed in the future.
-	if strings.Index(strings.ToLower(header["Content-Type"]), "multipart/byteranges") >= 0 {
+	if strings.Contains(strings.ToLower(header["Content-Type"]), "multipart/byteranges") {
 		return -1, ErrNotSupported
 	}
 
@@ -360,7 +360,7 @@ func shouldClose(major, minor int, header map[string]string) bool {
 			return true
 		}
 		v = strings.ToLower(v)
-		if strings.Index(v, "keep-alive") == -1 {
+		if !strings.Contains(v, "keep-alive") {
 			return true
 		}
 		return false

src/pkg/http/url.go

@@ -439,7 +439,7 @@ func ParseURL(rawurl string) (url *URL, err os.Error) {
 		// instead.  Clients that wish to use RawAuthority will have to
 		// interpret it themselves: RFC 2396 does not define the meaning.
 
-		if strings.Index(rawHost, "%") >= 0 {
+		if strings.Contains(rawHost, "%") {
 			// Host cannot contain escaped characters.
 			err = os.ErrorString("hexadecimal escape in host")
 			goto Error

src/pkg/smtp/smtp.go

@@ -57,7 +57,7 @@ func NewClient(conn net.Conn, host string) (*Client, os.Error) {
 		return nil, err
 	}
 	c := &Client{Text: text, conn: conn, serverName: host}
-	if strings.Index(msg, "ESMTP") >= 0 {
+	if strings.Contains(msg, "ESMTP") {
 		err = c.ehlo()
 	} else {
 		err = c.helo()

src/pkg/strconv/quote.go

@@ -234,7 +234,7 @@ func Unquote(s string) (t string, err os.Error) {
 	s = s[1 : n-1]
 
 	if quote == '`' {
-		if strings.Index(s, "`") >= 0 {
+		if strings.Contains(s, "`") {
 			return "", os.EINVAL
 		}
 		return s, nil

src/pkg/strings/strings.go

@@ -61,6 +61,11 @@ func Count(s, sep string) int {
 	return n
 }
 
+// Contains returns true if substr is within s.
+func Contains(s, substr string) bool {
+	return Index(s, substr) != -1
+}
+
 // 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 {
 	n := len(sep)

src/pkg/strings/strings_test.go

@@ -739,3 +739,24 @@ func TestTitle(t *testing.T) {
 		}
 	}
 }
+
+type ContainsTest struct {
+	str, substr string
+	expected    bool
+}
+
+var ContainsTests = []ContainsTest{
+	{"abc", "bc", true},
+	{"abc", "bcd", false},
+	{"abc", "", true},
+	{"", "a", false},
+}
+
+func TestContains(t *testing.T) {
+	for _, ct := range ContainsTests {
+		if Contains(ct.str, ct.substr) != ct.expected {
+			t.Errorf("Contains(%s, %s) = %v, want %v",
+				ct.str, ct.substr, !ct.expected, ct.expected)
+		}
+	}
+}