linkedlist - push/unshift

src/vs/base/common/callbackList.ts

@@ -16,7 +16,7 @@ export default class CallbackList {
 		if (!this._callbacks) {
 			this._callbacks = new LinkedList<[Function, any]>();
 		}
-		const remove = this._callbacks.insert([callback, context]);
+		const remove = this._callbacks.push([callback, context]);
 		if (Array.isArray(bucket)) {
 			bucket.push({ dispose: remove });
 		}

src/vs/base/common/linkedList.ts

@@ -24,16 +24,33 @@ export class LinkedList<E> {
 		return !this._first;
 	}
 
-	insert(element: E) {
+	unshift(element: E) {
+		return this.insert(element, false);
+	}
+
+	push(element: E) {
+		return this.insert(element, true);
+	}
+
+	private insert(element: E, atTheEnd: boolean) {
 		const newNode = new Node(element);
 		if (!this._first) {
 			this._first = newNode;
 			this._last = newNode;
-		} else {
+
+		} else if (atTheEnd) {
+			// push
 			const oldLast = this._last;
 			this._last = newNode;
 			newNode.prev = oldLast;
 			oldLast.next = newNode;
+
+		} else {
+			// unshift
+			const oldFirst = this._first;
+			this._first = newNode;
+			newNode.next = oldFirst;
+			oldFirst.prev = newNode;
 		}
 
 		return () => {

src/vs/base/test/common/linkedList.test.ts

@@ -21,43 +21,43 @@ suite('LinkedList', function () {
 		assert.equal(elements.length, 0);
 	}
 
-	test('Insert/Iter', function () {
+	test('Push/Iter', function () {
 		const list = new LinkedList<number>();
-		list.insert(0);
-		list.insert(1);
-		list.insert(2);
+		list.push(0);
+		list.push(1);
+		list.push(2);
 		assertElements(list, 0, 1, 2);
 	});
 
-	test('Insert/Remove', function () {
+	test('Push/Remove', function () {
 		let list = new LinkedList<number>();
-		let disp = list.insert(0);
-		list.insert(1);
-		list.insert(2);
+		let disp = list.push(0);
+		list.push(1);
+		list.push(2);
 		disp();
 		assertElements(list, 1, 2);
 
 		list = new LinkedList<number>();
-		list.insert(0);
-		disp = list.insert(1);
-		list.insert(2);
+		list.push(0);
+		disp = list.push(1);
+		list.push(2);
 		disp();
 		assertElements(list, 0, 2);
 
 		list = new LinkedList<number>();
-		list.insert(0);
-		list.insert(1);
-		disp = list.insert(2);
+		list.push(0);
+		list.push(1);
+		disp = list.push(2);
 		disp();
 		assertElements(list, 0, 1);
 	});
 
-	test('Insert/toArray', function () {
+	test('Push/toArray', function () {
 		let list = new LinkedList<string>();
-		list.insert('foo');
-		list.insert('bar');
-		list.insert('far');
-		list.insert('boo');
+		list.push('foo');
+		list.push('bar');
+		list.push('far');
+		list.push('boo');
 
 		assert.deepEqual(
 			list.toArray(),
@@ -69,4 +69,53 @@ suite('LinkedList', function () {
 			]
 		);
 	});
+
+	test('unshift/Iter', function () {
+		const list = new LinkedList<number>();
+		list.unshift(0);
+		list.unshift(1);
+		list.unshift(2);
+		assertElements(list, 2, 1, 0);
+	});
+
+	test('unshift/Remove', function () {
+		let list = new LinkedList<number>();
+		let disp = list.unshift(0);
+		list.unshift(1);
+		list.unshift(2);
+		disp();
+		assertElements(list, 2, 1);
+
+		list = new LinkedList<number>();
+		list.unshift(0);
+		disp = list.unshift(1);
+		list.unshift(2);
+		disp();
+		assertElements(list, 2, 0);
+
+		list = new LinkedList<number>();
+		list.unshift(0);
+		list.unshift(1);
+		disp = list.unshift(2);
+		disp();
+		assertElements(list, 1, 0);
+	});
+
+	test('unshift/toArray', function () {
+		let list = new LinkedList<string>();
+		list.unshift('foo');
+		list.unshift('bar');
+		list.unshift('far');
+		list.unshift('boo');
+
+		assert.deepEqual(
+			list.toArray(),
+			[
+				'boo',
+				'far',
+				'bar',
+				'foo',
+			]
+		);
+	});
 });