Remove parents field for optimization (#527)

Author: ckganesan

Diff for: ast/node.go

@@ -133,6 +133,7 @@ type MemberNode struct {
 	Node     Node // Node of the member access. Like "foo" in "foo.bar".
 	Property Node // Property of the member access. For property access it is a StringNode.
 	Optional bool // If true then the member access is optional. Like "foo?.bar".
+	Method   bool
 }
 
 // SliceNode represents access to a slice of an array.

Diff for: checker/checker.go

@@ -54,7 +54,6 @@ type checker struct {
 	config          *conf.Config
 	predicateScopes []predicateScope
 	varScopes       []varScope
-	parents         []ast.Node
 	err             *file.Error
 }
 
@@ -83,7 +82,6 @@ type info struct {
 func (v *checker) visit(node ast.Node) (reflect.Type, info) {
 	var t reflect.Type
 	var i info
-	v.parents = append(v.parents, node)
 	switch n := node.(type) {
 	case *ast.NilNode:
 		t, i = v.NilNode(n)
@@ -130,7 +128,6 @@ func (v *checker) visit(node ast.Node) (reflect.Type, info) {
 	default:
 		panic(fmt.Sprintf("undefined node type (%T)", node))
 	}
-	v.parents = v.parents[:len(v.parents)-1]
 	node.SetType(t)
 	return t, i
 }
@@ -431,9 +428,6 @@ func (v *checker) ChainNode(node *ast.ChainNode) (reflect.Type, info) {
 }
 
 func (v *checker) MemberNode(node *ast.MemberNode) (reflect.Type, info) {
-	base, _ := v.visit(node.Node)
-	prop, _ := v.visit(node.Property)
-
 	// $env variable
 	if an, ok := node.Node.(*ast.IdentifierNode); ok && an.Value == "$env" {
 		if name, ok := node.Property.(*ast.StringNode); ok {
@@ -450,6 +444,9 @@ func (v *checker) MemberNode(node *ast.MemberNode) (reflect.Type, info) {
 		return anyType, info{}
 	}
 
+	base, _ := v.visit(node.Node)
+	prop, _ := v.visit(node.Property)
+
 	if name, ok := node.Property.(*ast.StringNode); ok {
 		if base == nil {
 			return v.error(node, "type %v has no field %v", base, name.Value)
@@ -498,10 +495,8 @@ func (v *checker) MemberNode(node *ast.MemberNode) (reflect.Type, info) {
 			if field, ok := fetchField(base, propertyName); ok {
 				return field.Type, info{}
 			}
-			if len(v.parents) > 1 {
-				if _, ok := v.parents[len(v.parents)-2].(*ast.CallNode); ok {
-					return v.error(node, "type %v has no method %v", base, propertyName)
-				}
+			if node.Method {
+				return v.error(node, "type %v has no method %v", base, propertyName)
 			}
 			return v.error(node, "type %v has no field %v", base, propertyName)
 		}

Diff for: parser/parser.go

@@ -572,6 +572,7 @@ func (p *parser) parsePostfixExpression(node Node) Node {
 			memberNode.SetLocation(propertyToken.Location)
 
 			if p.current.Is(Bracket, "(") {
+				memberNode.Method = true
 				node = &CallNode{
 					Callee:    memberNode,
 					Arguments: p.parseArguments(),

Diff for: parser/parser_test.go

@@ -178,13 +178,13 @@ world`},
 		{
 			"foo.bar()",
 			&CallNode{Callee: &MemberNode{Node: &IdentifierNode{Value: "foo"},
-				Property: &StringNode{Value: "bar"}},
+				Property: &StringNode{Value: "bar"}, Method: true},
 				Arguments: []Node{}},
 		},
 		{
 			`foo.bar("arg1", 2, true)`,
 			&CallNode{Callee: &MemberNode{Node: &IdentifierNode{Value: "foo"},
-				Property: &StringNode{Value: "bar"}},
+				Property: &StringNode{Value: "bar"}, Method: true},
 				Arguments: []Node{&StringNode{Value: "arg1"},
 					&IntegerNode{Value: 2},
 					&BoolNode{Value: true}}},
@@ -220,12 +220,14 @@ world`},
 									Property: &StringNode{
 										Value: "b",
 									},
+									Method: true,
 								},
 								Arguments: []Node{},
 							},
 							Property: &StringNode{
 								Value: "c",
 							},
+							Method: true,
 						},
 						Arguments: []Node{},
 					},