Add support for method of map.

eval_test.go

@@ -21,6 +21,22 @@ type evalErrorTest struct {
 	err   string
 }
 
+type evalParams map[string]interface{}
+
+func (p evalParams) Max(a, b float64) float64 {
+	if a < b {
+		return b
+	}
+	return a
+}
+
+func (p evalParams) Min(a, b float64) float64 {
+	if a < b {
+		return a
+	}
+	return b
+}
+
 var evalTests = []evalTest{
 	{
 		"foo",
@@ -339,6 +355,16 @@ var evalTests = []evalTest{
 		map[string]interface{}{"foo": func(in string) string { return "hello " + in }},
 		"hello world",
 	},
+	{
+		"Max(a, b)",
+		evalParams{"a": 1.23, "b": 3.21},
+		3.21,
+	},
+	{
+		"Min(a, b)",
+		evalParams{"a": 1.23, "b": 3.21},
+		1.23,
+	},
 }
 
 var evalErrorTests = []evalErrorTest{

runtime.go

@@ -83,7 +83,7 @@ func extract(val interface{}, i interface{}) (interface{}, bool) {
 	return nil, false
 }
 
-func getFunc(val interface{}, i interface{}) (interface{}, bool) {
+func getFunc(val interface{}, name string) (interface{}, bool) {
 	v := reflect.ValueOf(val)
 	d := v
 	if v.Kind() == reflect.Ptr {
@@ -92,12 +92,18 @@ func getFunc(val interface{}, i interface{}) (interface{}, bool) {
 
 	switch d.Kind() {
 	case reflect.Map:
-		value := d.MapIndex(reflect.ValueOf(i))
+		value := d.MapIndex(reflect.ValueOf(name))
 		if value.IsValid() && value.CanInterface() {
 			return value.Interface(), true
 		}
+		// A map may have method too.
+		if v.NumMethod() > 0 {
+			method := v.MethodByName(name)
+			if method.IsValid() && method.CanInterface() {
+				return method.Interface(), true
+			}
+		}
 	case reflect.Struct:
-		name := reflect.ValueOf(i).String()
 		method := v.MethodByName(name)
 		if method.IsValid() && method.CanInterface() {
 			return method.Interface(), true