Merge pull request #10 from superfell/get_key

Optimize map key check in get_key

Author: oliveagle

jsonpath.go

@@ -283,6 +283,16 @@ func get_key(obj interface{}, key string) (interface{}, error) {
 	}
 	switch reflect.TypeOf(obj).Kind() {
 	case reflect.Map:
+		// if obj came from stdlib json, its highly likely to be a map[string]interface{}
+		// in which case we can save having to iterate the map keys to work out if the
+		// key exists
+		if jsonMap, ok := obj.(map[string]interface{}); ok {
+			val, exists := jsonMap[key]
+			if !exists {
+				return nil, fmt.Errorf("key error: %s not found in object", key)
+			}
+			return val, nil
+		}
 		for _, kv := range reflect.ValueOf(obj).MapKeys() {
 			//fmt.Println(kv.String())
 			if kv.String() == key {

jsonpath_test.go

@@ -55,6 +55,18 @@ func init() {
 	json.Unmarshal([]byte(data), &json_data)
 }
 
+func Benchmark_JsonPathLookup(b *testing.B) {
+	for n := 0; n < b.N; n++ {
+		res, err := JsonPathLookup(json_data, "$.store.book[0].price")
+		if res_v, ok := res.(float64); ok != true || res_v != 8.95 {
+			b.Errorf("$.store.book[0].price should be 8.95")
+		}
+		if err != nil {
+			b.Errorf("Unexpected error: %v", err)
+		}
+	}
+}
+
 func Test_jsonpath_JsonPathLookup_1(t *testing.T) {
 	// key from root
 	res, _ := JsonPathLookup(json_data, "$.expensive")