From a9a2fe501a88334c633cc359f8ea44ad19523769 Mon Sep 17 00:00:00 2001
From: Cyrus Najmabadi <cyrusn@microsoft.com>
Date: Tue, 4 Nov 2014 19:30:28 -0800
Subject: [PATCH] Specialize computeData for arrays.

---
 src/services/syntax/syntaxElement.ts | 41 ++++++++++++++++++++++------
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/src/services/syntax/syntaxElement.ts b/src/services/syntax/syntaxElement.ts
index 4b1b1123f0d..0aa91d0aef0 100644
--- a/src/services/syntax/syntaxElement.ts
+++ b/src/services/syntax/syntaxElement.ts
@@ -334,27 +334,52 @@ module TypeScript {
         return info;
     }
 
-    function computeData(element: ISyntaxElement): number {
-        var slotCount = childCount(element);
+    function combineData(fullWidth: number, isIncrementallyUnusable: boolean) {
+        return (fullWidth << SyntaxConstants.NodeFullWidthShift)
+            | (isIncrementallyUnusable ? SyntaxConstants.NodeIncrementallyUnusableMask : 0)
+            | SyntaxConstants.NodeDataComputed;
+    }
 
+    function listComputeData(list: ISyntaxNodeOrToken[]): number {
         var fullWidth = 0;
+        var isIncrementallyUnusable = false;
+
+        for (var i = 0, n = list.length; i < n; i++) {
+            var child: ISyntaxElement = list[i];
+
+            fullWidth += TypeScript.fullWidth(child);
+            isIncrementallyUnusable = isIncrementallyUnusable || TypeScript.isIncrementallyUnusable(child);
+        }
+
+        return combineData(fullWidth, isIncrementallyUnusable);
+    }
+
+    function computeData(element: ISyntaxElement): number {
+        if (isList(element)) {
+            return listComputeData(<ISyntaxNodeOrToken[]>element);
+        }
+        else {
+            return nodeOrTokenComputeData(<ISyntaxNodeOrToken>element);
+        }
+    }
+
+    function nodeOrTokenComputeData(nodeOrToken: ISyntaxNodeOrToken) {
+        var fullWidth = 0;
+        var slotCount = nodeOrToken.childCount;
 
         // If we have no children (like an OmmittedExpressionSyntax), we're automatically not reusable.
-        var isIncrementallyUnusable = slotCount === 0 && !isList(element);
+        var isIncrementallyUnusable = slotCount === 0;
 
         for (var i = 0, n = slotCount; i < n; i++) {
-            var child = childAt(element, i);
+            var child = nodeOrToken.childAt(i);
 
             if (child) {
                 fullWidth += TypeScript.fullWidth(child);
-
                 isIncrementallyUnusable = isIncrementallyUnusable || TypeScript.isIncrementallyUnusable(child);
             }
         }
 
-        return (fullWidth << SyntaxConstants.NodeFullWidthShift)
-            | (isIncrementallyUnusable ? SyntaxConstants.NodeIncrementallyUnusableMask : 0)
-            | SyntaxConstants.NodeDataComputed;
+        return combineData(fullWidth, isIncrementallyUnusable);
     }
 
     export function start(element: ISyntaxElement, text?: ISimpleText): number {