Fix JSL parser returns entire data for non path attributes (#8)

Author: anush6898

package.json

@@ -1,6 +1,6 @@
 {
   "name": "json-selector-lang",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "description": "A tiny language for selecting JSON values",
   "main": "lib/index.js",
   "types": "lib/index.d.ts",

src/JSL.ts

@@ -17,7 +17,7 @@ class JSL {
     return parser.parseProgram();
   }
 
-  static evaluate(json: any, node: Program) {
+  static evaluate(json: any, node: Program): any {
     const evaluator = new JSLEvaluator();
 
     return evaluator.evaluate(json, node);

src/JSLEvaluator.ts

@@ -31,6 +31,10 @@ class JSLEvaluator {
   // -- Program evaluation --
 
   private evaluateProgram(program: Program, json: any): any {
+    if (program?.statements?.length === 0) {
+      return null;
+    }
+
     return program.statements.reduce((prev, statement) => this.evaluate(prev, statement), json);
   }
 

src/__tests__/JSLEvaluator.test.ts

@@ -119,4 +119,19 @@ describe('JSLEvaluator', () => {
       expect(returnedError[idx]).toEqual(testCase);
     });
   });
+
+  it('tests with valid jsl input', () => {
+    const input = '';
+    const json = { data: [{}, {}, { width: 200 }] };
+    try {
+      const program = JSL.compile(input);
+      const evaluator = new JSLEvaluator();
+      const e = evaluator.evaluate(json, program);
+
+      expect(e).toBeNull();
+    } catch (e: any) {
+      console.log(e);
+      fail();
+    }
+  });
 });