From e7e1fa72ec198f63d794abb296c4befb8b823dbb Mon Sep 17 00:00:00 2001
From: zhengbli <zhengbli@microsoft.com>
Date: Fri, 16 Oct 2015 12:00:31 -0700
Subject: [PATCH] Add sortBeforeComparison option back to arrayIsEqualTo

---
 src/compiler/tsc.ts          |  3 ++-
 src/compiler/utilities.ts    | 16 ++++++++++------
 src/server/editorServices.ts |  3 ++-
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index 5420caabe7c..b4774b9a842 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -360,7 +360,8 @@ namespace ts {
             let newFileNames = ts.map(parsedCommandLine.fileNames, compilerHost.getCanonicalFileName);
             let canonicalRootFileNames = ts.map(rootFileNames, compilerHost.getCanonicalFileName);
 
-            if (!arrayIsEqualTo(newFileNames.sort(), canonicalRootFileNames.sort())) {
+            // We check if the project file list has changed. If so, we just throw away the old program and start fresh.
+            if (!arrayIsEqualTo(newFileNames, canonicalRootFileNames, /*equaler*/ undefined, /*sortBeforeComparison*/ true)) {
                 setCachedProgram(undefined);
                 startTimerForRecompilation();
             }
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 2a16c2c71fb..b56c63013aa 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -82,17 +82,21 @@ namespace ts {
         return node.end - node.pos;
     }
 
-    export function arrayIsEqualTo<T>(arr1: T[], arr2: T[], comparer?: (a: T, b: T) => boolean): boolean {
-        if (!arr1 || !arr2) {
-            return arr1 === arr2;
+    export function arrayIsEqualTo<T>(array1: T[], array2: T[], equaler?: (a: T, b: T) => boolean,
+        sortBeforeComparison?: boolean, comparer?: (a: T, b: T) => number): boolean {
+        if (!array1 || !array2) {
+            return array1 === array2;
         }
 
-        if (arr1.length !== arr2.length) {
+        if (array1.length !== array2.length) {
             return false;
         }
 
-        for (let i = 0; i < arr1.length; ++i) {
-            let equals = comparer ? comparer(arr1[i], arr2[i]) : arr1[i] === arr2[i];
+        let newArray1 = sortBeforeComparison ? array1.slice().sort(comparer) : array1;
+        let newArray2 = sortBeforeComparison ? array2.slice().sort(comparer) : array2;
+
+        for (let i = 0; i < array1.length; ++i) {
+            let equals = equaler ? equaler(newArray1[i], newArray2[i]) : newArray1[i] === newArray2[i];
             if (!equals) {
                 return false;
             }
diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index b98129f99e9..7cb047bb74d 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -576,7 +576,8 @@ namespace ts.server {
             let newRootFiles = projectOptions.files.map((f => this.getCanonicalFileName(f)));
             let currentRootFiles = project.getRootFiles().map((f => this.getCanonicalFileName(f)));
 
-            if (!arrayIsEqualTo(currentRootFiles.sort(), newRootFiles.sort())) {
+            // We check if the project file list has changed. If so, we update the project.
+            if (!arrayIsEqualTo(currentRootFiles, newRootFiles, /*equaler*/ undefined, /*sortBeforeComparison*/ true)) {
                 // For configured projects, the change is made outside the tsconfig file, and
                 // it is not likely to affect the project for other files opened by the client. We can 
                 // just update the current project.