Remove isChild from fastJsonNode (#5184)

While forming JSON response from Subgraph, we build one intermediate data structure called
fastJsonNode tree. Each fastJsonNode has some fields which help correct encoding to JSON.
isChild and list are also part of these fields.
Currently isChild and list are used interchangeably and serve same purpose. This PR remove
isChild for simplicity and better readability of the code.

query/outputnode.go

@@ -55,10 +55,9 @@ func ToJson(l *Latency, sgl []*SubGraph) ([]byte, error) {
 	return sgr.toFastJSON(l)
 }
 
-func makeScalarNode(attr string, isChild bool, val []byte, list bool) *fastJsonNode {
+func makeScalarNode(attr string, val []byte, list bool) *fastJsonNode {
 	return &fastJsonNode{
 		attr:      attr,
-		isChild:   isChild,
 		scalarVal: val,
 		list:      list,
 	}
@@ -67,7 +66,6 @@ func makeScalarNode(attr string, isChild bool, val []byte, list bool) *fastJsonN
 type fastJsonNode struct {
 	attr      string
 	order     int // relative ordering (for sorted results)
-	isChild   bool
 	scalarVal []byte
 	attrs     []*fastJsonNode
 	list      bool
@@ -79,7 +77,7 @@ func (fj *fastJsonNode) AddValue(attr string, v types.Val) {
 
 func (fj *fastJsonNode) AddListValue(attr string, v types.Val, list bool) {
 	if bs, err := valToBytes(v); err == nil {
-		fj.attrs = append(fj.attrs, makeScalarNode(attr, false, bs, list))
+		fj.attrs = append(fj.attrs, makeScalarNode(attr, bs, list))
 	}
 }
 
@@ -93,24 +91,21 @@ func (fj *fastJsonNode) AddMapChild(attr string, val *fastJsonNode, isRoot bool)
 	}
 
 	if childNode != nil {
-		val.isChild = true
-		val.attr = attr
 		childNode.attrs = append(childNode.attrs, val.attrs...)
 	} else {
-		val.isChild = false
 		val.attr = attr
 		fj.attrs = append(fj.attrs, val)
 	}
 }
 
 func (fj *fastJsonNode) AddListChild(attr string, child *fastJsonNode) {
 	child.attr = attr
-	child.isChild = true
+	child.list = true
 	fj.attrs = append(fj.attrs, child)
 }
 
 func (fj *fastJsonNode) New(attr string) *fastJsonNode {
-	return &fastJsonNode{attr: attr, isChild: false}
+	return &fastJsonNode{attr: attr}
 }
 
 func (fj *fastJsonNode) SetUID(uid uint64, attr string) {
@@ -122,8 +117,7 @@ func (fj *fastJsonNode) SetUID(uid uint64, attr string) {
 			}
 		}
 	}
-	fj.attrs = append(fj.attrs, makeScalarNode(attr, false, []byte(fmt.Sprintf("\"%#x\"", uid)),
-		false))
+	fj.attrs = append(fj.attrs, makeScalarNode(attr, []byte(fmt.Sprintf("\"%#x\"", uid)), false))
 }
 
 func (fj *fastJsonNode) IsEmpty() bool {
@@ -288,7 +282,7 @@ func (fj *fastJsonNode) encode(out *bytes.Buffer) error {
 						if err := cur.writeKey(out); err != nil {
 							return err
 						}
-						if cur.isChild || cur.list {
+						if cur.list {
 							if _, err := out.WriteRune('['); err != nil {
 								return err
 							}
@@ -298,7 +292,7 @@ func (fj *fastJsonNode) encode(out *bytes.Buffer) error {
 					if err := cur.encode(out); err != nil {
 						return err
 					}
-					if cnt != 1 || (cur.isChild || cur.list) {
+					if cnt != 1 || cur.list {
 						if _, err := out.WriteRune(']'); err != nil {
 							return err
 						}
@@ -317,15 +311,15 @@ func (fj *fastJsonNode) encode(out *bytes.Buffer) error {
 						return err
 					}
 				}
-				if (cur.isChild || cur.list) && !inArray {
+				if cur.list && !inArray {
 					if _, err := out.WriteRune('['); err != nil {
 						return err
 					}
 				}
 				if err := cur.encode(out); err != nil {
 					return err
 				}
-				if cnt != 1 || (cur.isChild || cur.list) {
+				if cnt != 1 || cur.list {
 					if _, err := out.WriteRune(']'); err != nil {
 						return err
 					}
@@ -618,6 +612,7 @@ func (sg *SubGraph) toFastJSON(l *Latency) ([]byte, error) {
 			return nil, err
 		}
 	}
+
 	return bufw.Bytes(), nil
 }