Merge pull request #338 from francois-berder/optimize-hastag

Optimize HasTag function

proptools/tag.go

@@ -23,10 +23,17 @@ import (
 // HasTag returns true if a StructField has a tag in the form `name:"foo,value"`.
 func HasTag(field reflect.StructField, name, value string) bool {
 	tag := field.Tag.Get(name)
-	for _, entry := range strings.Split(tag, ",") {
-		if entry == value {
+	for len(tag) > 0 {
+		idx := strings.Index(tag, ",")
+
+		if idx < 0 {
+			return tag == value
+		}
+		if tag[:idx] == value {
 			return true
 		}
+
+		tag = tag[idx+1:]
 	}
 
 	return false

proptools/tag_test.go

@@ -19,16 +19,16 @@ import (
 	"testing"
 )
 
-func TestHasTag(t *testing.T) {
-	type testType struct {
-		NoTag       string
-		EmptyTag    string ``
-		OtherTag    string `foo:"bar"`
-		MatchingTag string `name:"value"`
-		ExtraValues string `name:"foo,value,bar"`
-		ExtraTags   string `foo:"bar" name:"value"`
-	}
+type testType struct {
+	NoTag       string
+	EmptyTag    string ``
+	OtherTag    string `foo:"bar"`
+	MatchingTag string `name:"value"`
+	ExtraValues string `name:"foo,value,bar"`
+	ExtraTags   string `foo:"bar" name:"value"`
+}
 
+func TestHasTag(t *testing.T) {
 	tests := []struct {
 		field string
 		want  bool
@@ -68,6 +68,39 @@ func TestHasTag(t *testing.T) {
 	}
 }
 
+func BenchmarkHasTag(b *testing.B) {
+	tests := []struct {
+		field string
+	}{
+		{
+			field: "NoTag",
+		},
+		{
+			field: "EmptyTag",
+		},
+		{
+			field: "OtherTag",
+		},
+		{
+			field: "MatchingTag",
+		},
+		{
+			field: "ExtraValues",
+		},
+		{
+			field: "ExtraTags",
+		},
+	}
+	for _, test := range tests {
+		b.Run(test.field, func(b *testing.B) {
+			field, _ := reflect.TypeOf(testType{}).FieldByName(test.field)
+			for i := 0; i < b.N; i++ {
+				HasTag(field, "name", "value")
+			}
+		})
+	}
+}
+
 func TestPropertyIndexesWithTag(t *testing.T) {
 	tests := []struct {
 		name string