Merge pull request #4 from itchyny/reduce-allocation

Reduce allocations by avoiding strings.Split

decode.go

@@ -44,14 +44,23 @@ type ltsvMap map[string]string
 
 func data2map(data []byte) (ltsvMap, error) {
 	d := string(data)
-	fields := strings.Split(d, "\t")
 	l := ltsvMap{}
-	for _, v := range fields {
-		kv := strings.SplitN(strings.TrimSpace(v), ":", 2)
-		if len(kv) != 2 {
+	var i int
+	var v string
+	for i < len(d) {
+		j := strings.IndexByte(d[i:], '\t')
+		if j >= 0 {
+			v = d[i : i+j]
+			i += j + 1
+		} else {
+			v = d[i:]
+			i = len(d)
+		}
+		k := strings.IndexByte(v, ':')
+		if k < 0 {
 			return nil, fmt.Errorf("not a ltsv: %s", d)
 		}
-		l[strings.TrimSpace(kv[0])] = strings.TrimSpace(kv[1])
+		l[strings.TrimSpace(v[:k])] = strings.TrimSpace(v[k+1:])
 	}
 	return l, nil
 }
@@ -93,9 +102,10 @@ func Unmarshal(data []byte, v interface{}) error {
 		ft := t.Field(i)
 		fv := rv.Field(i)
 
-		tag := ft.Tag.Get("ltsv")
-		tags := strings.Split(tag, ",")
-		key := tags[0]
+		key := ft.Tag.Get("ltsv")
+		if i := strings.IndexByte(key, ','); i >= 0 {
+			key = key[:i]
+		}
 		if key == "-" {
 			continue
 		}

decode_test.go

@@ -96,3 +96,15 @@ func TestUnmarshal(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkUnmarshalStruct(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tt := range decodeTests {
+			s := &ss{}
+			err := Unmarshal([]byte(tt.Input), s)
+			if err != nil {
+				b.Error(err)
+			}
+		}
+	}
+}

encode.go

@@ -66,9 +66,10 @@ func makeStructWriter(v reflect.Value) fieldWriter {
 	writers := make([]fieldWriter, n)
 	for i := 0; i < n; i++ {
 		ft := t.Field(i)
-		tag := ft.Tag.Get("ltsv")
-		tags := strings.Split(tag, ",")
-		key := tags[0]
+		key := ft.Tag.Get("ltsv")
+		if i := strings.IndexByte(key, ','); i >= 0 {
+			key = key[:i]
+		}
 		if key == "-" {
 			continue
 		}