diff --git a/src/vs/base/common/map.ts b/src/vs/base/common/map.ts
index aaad604db4c..b79e3bd0c53 100644
--- a/src/vs/base/common/map.ts
+++ b/src/vs/base/common/map.ts
@@ -40,6 +40,17 @@ export class LinkedMap<K extends Key, T> {
 		return value ? value : null;
 	}
 
+	public getOrSet(k: K, t: T): T {
+		const res = this.get(k);
+		if (res) {
+			return res;
+		}
+
+		this.set(k, t);
+
+		return t;
+	}
+
 	public keys(): K[] {
 		var keys: K[] = [];
 		for (let key in this.map) {
@@ -152,6 +163,17 @@ export class BoundedLinkedMap<T> {
 		return entry ? entry.value : null;
 	}
 
+	public getOrSet(k: string, t: T): T {
+		const res = this.get(k);
+		if (res) {
+			return res;
+		}
+
+		this.set(k, t);
+
+		return t;
+	}
+
 	public delete(key: string): T {
 		const entry = this.map[key];
 
@@ -273,4 +295,4 @@ export class LRUCache<T> extends BoundedLinkedMap<T> {
 
 		return null;
 	}
-}
\ No newline at end of file
+}
diff --git a/src/vs/base/test/common/map.test.ts b/src/vs/base/test/common/map.test.ts
index 25e796b2339..6c219c8fd8e 100644
--- a/src/vs/base/test/common/map.test.ts
+++ b/src/vs/base/test/common/map.test.ts
@@ -5,10 +5,72 @@
 
 'use strict';
 
-import {BoundedLinkedMap, LRUCache} from 'vs/base/common/map';
+import {BoundedLinkedMap, LRUCache, LinkedMap} from 'vs/base/common/map';
 import * as assert from 'assert';
 
 suite('Map', () => {
+
+	test('LinkedMap - basics', function () {
+		const map = new LinkedMap<string, any>();
+
+		assert.equal(map.size, 0);
+
+		map.set('1', 1);
+		map.set('2', '2');
+		map.set('3', true);
+
+		const obj = Object.create(null);
+		map.set('4', obj);
+
+		const date = Date.now();
+		map.set('5', date);
+
+		assert.equal(map.size, 5);
+		assert.equal(map.get('1'), 1);
+		assert.equal(map.get('2'), '2');
+		assert.equal(map.get('3'), true);
+		assert.equal(map.get('4'), obj);
+		assert.equal(map.get('5'), date);
+		assert.ok(!map.get('6'));
+
+		map.delete('6');
+		assert.equal(map.size, 5);
+		assert.equal(map.delete('1'), 1);
+		assert.equal(map.delete('2'), '2');
+		assert.equal(map.delete('3'), true);
+		assert.equal(map.delete('4'), obj);
+		assert.equal(map.delete('5'), date);
+
+		assert.equal(map.size, 0);
+		assert.ok(!map.get('5'));
+		assert.ok(!map.get('4'));
+		assert.ok(!map.get('3'));
+		assert.ok(!map.get('2'));
+		assert.ok(!map.get('1'));
+
+		map.set('1', 1);
+		map.set('2', '2');
+		assert.ok(map.set('3', true)); // adding an element returns true
+		assert.ok(!map.set('3', true)); // adding it again returns false
+
+		assert.ok(map.has('1'));
+		assert.equal(map.get('1'), 1);
+		assert.equal(map.get('2'), '2');
+		assert.equal(map.get('3'), true);
+
+		map.clear();
+
+		assert.equal(map.size, 0);
+		assert.ok(!map.get('1'));
+		assert.ok(!map.get('2'));
+		assert.ok(!map.get('3'));
+		assert.ok(!map.has('1'));
+
+		const res = map.getOrSet('foo', 'bar');
+		assert.equal(map.get('foo'), res);
+		assert.equal(res, 'bar');
+	});
+
 	test('BoundedLinkedMap - basics', function () {
 		const map = new BoundedLinkedMap<any>();
 
@@ -64,6 +126,10 @@ suite('Map', () => {
 		assert.ok(!map.get('2'));
 		assert.ok(!map.get('3'));
 		assert.ok(!map.has('1'));
+
+		const res = map.getOrSet('foo', 'bar');
+		assert.equal(map.get('foo'), res);
+		assert.equal(res, 'bar');
 	});
 
 	test('BoundedLinkedMap - bounded', function () {
@@ -204,6 +270,5 @@ suite('Map', () => {
 		assert.equal(cache.get('6'), 6);
 		assert.ok(!cache.has('3'));
 		assert.ok(!cache.has('4'));
-
 	});
 });