nycdotnet
diff --git a/‎src/compiler/parser.ts
Lines changed: 18 additions & 14 deletions b/‎src/compiler/parser.ts
Lines changed: 18 additions & 14 deletions
@@ -683,24 +683,12 @@ module ts {
         }
     }
 
-
-    // Produces a new SourceFile for the 'newText' provided. The 'textChangeRange' parameter 
-    // indicates what changed between the 'text' that this SourceFile has and the 'newText'.
-    // The SourceFile will be created with the compiler attempting to reuse as many nodes from 
-    // this file as possible.
-    //
-    // Note: this function mutates nodes from this SourceFile. That means any existing nodes
-    // from this SourceFile that are being held onto may change as a result (including 
-    // becoming detached from any SourceFile).  It is recommended that this SourceFile not
-    // be used once 'update' is called on it.
-    export function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile {
-        aggressiveChecks = aggressiveChecks || Debug.shouldAssert(AssertionLevel.Aggressive);
-
+    function checkChangeRange(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks: boolean) {
         var oldText = sourceFile.text;
         if (textChangeRange) {
             Debug.assert((oldText.length - textChangeRange.span.length + textChangeRange.newLength) === newText.length);
 
-            if (Debug.shouldAssert(AssertionLevel.VeryAggressive)) {
+            if (aggressiveChecks || Debug.shouldAssert(AssertionLevel.VeryAggressive)) {
                 var oldTextPrefix = oldText.substr(0, textChangeRange.span.start);
                 var newTextPrefix = newText.substr(0, textChangeRange.span.start);
                 Debug.assert(oldTextPrefix === newTextPrefix);
@@ -710,7 +698,21 @@ module ts {
                 Debug.assert(oldTextSuffix === newTextSuffix);
             }
         }
+    }
 
+    // Produces a new SourceFile for the 'newText' provided. The 'textChangeRange' parameter 
+    // indicates what changed between the 'text' that this SourceFile has and the 'newText'.
+    // The SourceFile will be created with the compiler attempting to reuse as many nodes from 
+    // this file as possible.
+    //
+    // Note: this function mutates nodes from this SourceFile. That means any existing nodes
+    // from this SourceFile that are being held onto may change as a result (including 
+    // becoming detached from any SourceFile).  It is recommended that this SourceFile not
+    // be used once 'update' is called on it.
+    export function updateSourceFile(sourceFile: SourceFile, newText: string, textChangeRange: TextChangeRange, aggressiveChecks?: boolean): SourceFile {
+        aggressiveChecks = aggressiveChecks || Debug.shouldAssert(AssertionLevel.Aggressive);
+
+        checkChangeRange(sourceFile, newText, textChangeRange, aggressiveChecks);
         if (textChangeRangeIsUnchanged(textChangeRange)) {
             // if the text didn't change, then we can just return our current source file as-is.
             return sourceFile;
@@ -722,11 +724,13 @@ module ts {
             return parseSourceFile(sourceFile.fileName, newText, sourceFile.languageVersion,/*syntaxCursor*/ undefined, /*setNodeParents*/ true)
         }
+        var oldText = sourceFile.text;
         var syntaxCursor = createSyntaxCursor(sourceFile);
 
         // Make the actual change larger so that we know to reparse anything whose lookahead 
         // might have intersected the change.
         var changeRange = extendToAffectedRange(sourceFile, textChangeRange);
+        checkChangeRange(sourceFile, newText, changeRange, aggressiveChecks);
 
         // Ensure that extending the affected range only moved the start of the change range 
         // earlier in the file.