From 8c37045f3734950fad052369b77e83d0571e240e Mon Sep 17 00:00:00 2001
From: Theo Sun <theo.sun@sap.com>
Date: Fri, 10 Jul 2020 13:18:44 +0800
Subject: [PATCH] fix: visit undefine object will throw error

---
 src/visitor.ts       | 38 +++++++++++++++++++-------------------
 test/query.spec.ts   |  9 +++++++++
 test/visitor.spec.ts |  5 +++++
 3 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/src/visitor.ts b/src/visitor.ts
index f1155ea..6dab7c3 100644
--- a/src/visitor.ts
+++ b/src/visitor.ts
@@ -24,37 +24,37 @@ export type Visitor = Traverser
 export function traverseAst(traverser: Traverser, node: Token, parent?: Token): void {
 
   if (node instanceof Token) {
-    if (node.type in traverser) {
-      traverser[node.type](node, parent);
+    if (node?.type in traverser) {
+      traverser[node?.type](node, parent);
     }
   }
 
-  if (isArray(node.value) || isPlainObject(node.value)) {
-    forEach(node.value, (item) => {
+  if (isArray(node?.value) || isPlainObject(node?.value)) {
+    forEach(node?.value, (item) => {
       if (item instanceof Token) {
         traverseAst(traverser, item, node);
       }
     });
   }
 
-  if (isArray(node.value?.options)) {
-    forEach(node.value?.options, (item) => {
+  if (isArray(node?.value?.options)) {
+    forEach(node?.value?.options, (item) => {
       if (item instanceof Token) {
         traverseAst(traverser, item, node);
       }
     });
   }
 
-  if (isArray(node.value?.items)) {
-    forEach(node.value?.items, (item) => {
+  if (isArray(node?.value?.items)) {
+    forEach(node?.value?.items, (item) => {
       if (item instanceof Token) {
         traverseAst(traverser, item, node);
       }
     });
   }
 
-  if (node.value instanceof Token) {
-    traverseAst(traverser, node.value, node);
+  if (node?.value instanceof Token) {
+    traverseAst(traverser, node?.value, node);
   }
 
 }
@@ -68,28 +68,28 @@ export function traverseAst(traverser: Traverser, node: Token, parent?: Token):
  */
 export function traverseAstDeepFirst(traverser: Traverser, node: Token, parent?: Token): void {
 
-  if (isArray(node.value) || isPlainObject(node.value)) {
-    forEach(node.value, (item) => {
+  if (isArray(node?.value) || isPlainObject(node?.value)) {
+    forEach(node?.value, (item) => {
       if (item instanceof Token) {
         traverseAstDeepFirst(traverser, item, node);
       }
     });
   }
 
-  if (node.value instanceof Token) {
-    traverseAstDeepFirst(traverser, node.value, node);
+  if (node?.value instanceof Token) {
+    traverseAstDeepFirst(traverser, node?.value, node);
   }
 
-  if (isArray(node.value?.options)) {
-    forEach(node.value?.options, (item) => {
+  if (isArray(node?.value?.options)) {
+    forEach(node?.value?.options, (item) => {
       if (item instanceof Token) {
         traverseAstDeepFirst(traverser, item, node);
       }
     });
   }
 
-  if (isArray(node.value?.items)) {
-    forEach(node.value?.items, (item) => {
+  if (isArray(node?.value?.items)) {
+    forEach(node?.value?.items, (item) => {
       if (item instanceof Token) {
         traverseAstDeepFirst(traverser, item, node);
       }
@@ -97,7 +97,7 @@ export function traverseAstDeepFirst(traverser: Traverser, node: Token, parent?:
   }
 
   if (node instanceof Token) {
-    if (node.type in traverser) {
+    if (node?.type in traverser) {
       traverser[node.type](node, parent);
     }
   }
diff --git a/test/query.spec.ts b/test/query.spec.ts
index ecaca10..d49e5d9 100644
--- a/test/query.spec.ts
+++ b/test/query.spec.ts
@@ -3,6 +3,7 @@ import { findOne, findAll } from '../src/utils';
 import { TokenType } from '../src/lexer';
 import { get } from '@newdash/newdash';
 import { defaultParser } from '../src';
+import { execPath } from 'process';
 
 describe('Query Test Suite', () => {
 
@@ -70,4 +71,12 @@ describe('Query Test Suite', () => {
     expect(node).not.toBeUndefined();
   });
 
+  it('should parse $filter only', () => {
+    const ast = defaultParser.query('$filter=id eq 1');
+    expect(ast).not.toBeUndefined();
+    expect(ast.value.options).not.toBeUndefined();
+    expect(ast.value.options).toHaveLength(1);
+
+  });
+
 });
diff --git a/test/visitor.spec.ts b/test/visitor.spec.ts
index 47ac2c0..fe34d34 100644
--- a/test/visitor.spec.ts
+++ b/test/visitor.spec.ts
@@ -55,4 +55,9 @@ describe('Visitor Parse Suite', () => {
 
   });
 
+  it('should support visit undefined', () => {
+    const { visit, visitSequence } = createSeqTraverser(true);
+    visit(undefined);
+  });
+
 });