Merge branch 'master' of https://github.com/Microsoft/TypeScript into i4420

# Conflicts: #	src/server/session.ts

Author: zhengbli

src/compiler/core.ts

@@ -91,10 +91,10 @@ namespace ts {
  return undefined;
  }
 
- export function contains<T>(array: T[], value: T): boolean {
+ export function contains<T>(array: T[], value: T, areEqual?: (a: T, b: T) => boolean): boolean {
  if (array) {
  for (const v of array) {
- if (v === value) {
+ if (areEqual ? areEqual(v, value) : v === value) {
  return true;
  }
  }
@@ -156,12 +156,12 @@ namespace ts {
  return array1.concat(array2);
  }
 
- export function deduplicate<T>(array: T[]): T[] {
+ export function deduplicate<T>(array: T[], areEqual?: (a: T, b: T) => boolean): T[] {
  let result: T[];
  if (array) {
  result = [];
  for (const item of array) {
- if (!contains(result, item)) {
+ if (!contains(result, item, areEqual)) {
  result.push(item);
  }
  }

src/server/editorServices.ts

@@ -498,6 +498,14 @@ namespace ts.server {
  return copiedList;
  }
 
+ /**
+ * This helper funciton processes a list of projects and return the concatenated, sortd and deduplicated output of processing each project.
+ */
+ export function combineProjectOutput<T>(projects: Project[], action: (project: Project) => T[], comparer?: (a: T, b: T) => number, areEqual?: (a: T, b: T) => boolean) {
+ const result = projects.reduce<T[]>((previous, current) => concatenate(previous, action(current)), []).sort(comparer);
+ return projects.length > 1 ? deduplicate(result, areEqual) : result;
+ }
+
  export interface ProjectServiceEventHandler {
  (eventName: string, project: Project, fileName: string): void;
  }