feat: array access & object access

src/grammar.js

@@ -16,14 +16,32 @@ import {
 }
 from './functions';
 
+function Error(error) {
+	return createValue(Promise.reject(error));
+}
+
 class AST {
 	get value() {
 		return undefined;
 	}
 }
 
-function Error(error) {
-	return createValue(Promise.reject(error));
+class ArrayAccess extends AST {
+	constructor(array, index) {
+		super();
+		Object.defineProperty(this, 'value', {
+			get: () => array.value[index.value]
+		});
+	}
+}
+
+class ObjectAccess extends AST {
+	constructor(object, attribute) {
+		super();
+		Object.defineProperty(this, 'value', {
+			get: () => object.value[attribute.value]
+		});
+	}
 }
 
 class BinOP extends AST {
@@ -118,6 +136,15 @@ export const grammar = create({
 			}
 		},
 		infix: {
+			'.': {
+				precedence: 1,
+				combine: (left, right) => new ObjectAccess(left, right)
+			},
+			'[': {
+				precedence: 1,
+				combine: (left, right) => new ArrayAccess(left, right)
+			},
+			']': {},
 			',': {},
 			')': {},
 			'+': {

tests/simple_test.js

@@ -162,4 +162,32 @@ describe('expander', () => {
     it('include missing', () => expand("${include('fixtures/missing.json')}").catch(e => assert.equal(e.message,
       'ENOENT: no such file or directory, open \'/fixtures/missing.json\'')));
   });
+
+  describe('arrays', () => {
+    it('access', () => expand("${myArray[2-1]}", {
+      constants: {
+        myArray: ['a', 'b', 'c'],
+      }
+    }).then(r => assert.equal(r, 'b')));
+  });
+
+  describe('object paths', () => {
+    it('access one level', () => expand("${myObject.att1}", {
+      constants: {
+        myObject: {
+          att1: 'val1'
+        },
+      }
+    }).then(r => assert.equal(r, 'val1')));
+
+    it('access several levels', () => expand("${myObject.level1.level2}", {
+      constants: {
+        myObject: {
+          level1: {
+            level2: 'val1'
+          }
+        },
+      }
+    }).then(r => assert.equal(r, 'val1')));
+  });
 });