get childNodeRange of empty parameters

Author: flyerhzm

src/adapter/typescript.ts

@@ -72,7 +72,11 @@ class TypescriptAdapter implements Adapter<Node> {
   childNodeRange(node: Node, childName: string): { start: number, end: number } {
     if (["arguments", "parameters"].includes(childName)) {
       const elements = (node as any)[childName];
-      return { start: this.getStart(elements[0] as Node) - 1, end: this.getEnd(elements[elements.length - 1] as Node) + 1 };
+      if (Array.isArray(elements) && elements.hasOwnProperty('0')) {
+        return { start: this.getStart(elements[0] as Node) - 1, end: this.getEnd(elements[elements.length - 1] as Node) + 1 };
+      } else {
+        return { start: elements['pos'] - 1, end: elements['pos'] + 1 };
+      }
     } else if (node.kind === SyntaxKind.PropertyAssignment && childName === "semicolon") {
       return { start: this.getEnd((node as PropertyAssignment).name), end: this.getEnd((node as PropertyAssignment).name) + 1 };
     } else if (node.kind === SyntaxKind.PropertyAccessExpression && childName === "dot") {

test/adapter/typescript.spec.ts

@@ -100,6 +100,11 @@ describe("TypescriptAdapter", () => {
   });
 
   describe("#childNodeRange", () => {
+    test("ArrowFunction parameters", () => {
+      const node = (parseCode("const foobar = () => {}") as any)['declarationList']['declarations'][0]['initializer'];
+      expect(adapter.childNodeRange(node, "parameters")).toEqual({ start: 15, end: 17 });
+    });
+
     test("FunctionDeclaration parameters", () => {
       const node = parseCode("function foobar(foo, bar) {}");
       expect(adapter.childNodeRange(node, "parameters")).toEqual({ start: 15, end: 25 });