Patch up signature help after the bug in getTokenAtPosition

Author: JsonFreeman

src/services/formatting/smartIndenter.ts

@@ -7,7 +7,7 @@ module ts.formatting {
                 return 0; // past EOF
             }
 
-            var precedingToken = ServicesSyntaxUtilities.findPrecedingToken(position, sourceFile);
+            var precedingToken = findPrecedingToken(position, sourceFile);
             if (!precedingToken) {
                 return 0;
             }
@@ -107,7 +107,7 @@ module ts.formatting {
          */ 
         function getActualIndentationForListItemBeforeComma(commaToken: Node, sourceFile: SourceFile, options: TypeScript.FormattingOptions): number {
             // previous token is comma that separates items in list - find the previous item and try to derive indentation from it
-            var commaItemInfo = ServicesSyntaxUtilities.findListItemInfo(commaToken);
+            var commaItemInfo = findListItemInfo(commaToken);
             Debug.assert(commaItemInfo.listItemIndex > 0);
             // The item we're interested in is right before the comma
             return deriveActualIndentationFromList(commaItemInfo.list.getChildren(), commaItemInfo.listItemIndex - 1, sourceFile, options);
@@ -138,7 +138,7 @@ module ts.formatting {
         }
 
         function nextTokenIsCurlyBraceOnSameLineAsCursor(precedingToken: Node, current: Node, lineAtPosition: number, sourceFile: SourceFile): boolean {
-            var nextToken = ServicesSyntaxUtilities.findNextToken(precedingToken, current);
+            var nextToken = findNextToken(precedingToken, current);
             if (!nextToken) {
                 return false;
             }

src/services/services.ts

@@ -2085,22 +2085,6 @@ module ts {
             }
         }
 
-        /** Get the token whose text contains the position, or the containing node. */
-        function getNodeAtPosition(sourceFile: SourceFile, position: number) {
-            var current: Node = sourceFile;
-            outer: while (true) {
-                // find the child that has this
-                for (var i = 0, n = current.getChildCount(); i < n; i++) {
-                    var child = current.getChildAt(i);
-                    if (child.getStart() <= position && position < child.getEnd()) {
-                        current = child;
-                        continue outer;
-                    }
-                }
-                return current;
-            }
-        }
-
         function getContainerNode(node: Node): Node {
             while (true) {
                 node = node.parent;
@@ -3874,7 +3858,7 @@ module ts {
 
                     // OK, we have found a match in the file.  This is only an acceptable match if
                     // it is contained within a comment.
-                    var token = ServicesSyntaxUtilities.getTokenAtPosition(sourceFile, matchPosition);
+                    var token = getTokenAtPosition(sourceFile, matchPosition);
 
                     if (token.getStart() <= matchPosition && matchPosition < token.getEnd()) {
                         // match was within the token itself.  Not in the comment.  Keep searching

src/services/servicesSyntaxUtilities.ts

@@ -1,5 +1,5 @@
 // These utilities are common to multiple language service features.
-module ts.ServicesSyntaxUtilities {
+module ts {
     export interface ListItemInfo {
         listItemIndex: number;
         list: Node;
@@ -62,6 +62,22 @@ module ts.ServicesSyntaxUtilities {
         }
     }
 
+    /** Get the token whose text contains the position, or the containing node. */
+    export function getNodeAtPosition(sourceFile: SourceFile, position: number) {
+        var current: Node = sourceFile;
+        outer: while (true) {
+            // find the child that has this
+            for (var i = 0, n = current.getChildCount(); i < n; i++) {
+                var child = current.getChildAt(i);
+                if (child.getStart() <= position && position < child.getEnd()) {
+                    current = child;
+                    continue outer;
+                }
+            }
+            return current;
+        }
+    }
+
     /**
       * The token on the left of the position is the token that strictly includes the position
       * or sits to the left of the cursor if it is on a boundary. For example
@@ -71,8 +87,10 @@ module ts.ServicesSyntaxUtilities {
       *
       */
     export function findTokenOnLeftOfPosition(file: SourceFile, position: number): Node {
+        // Ideally, getTokenAtPosition should return a token. However, it is currently
+        // broken, so we do a check to make sure the result was indeed a token.
         var tokenAtPosition = getTokenAtPosition(file, position);
-        if (position > tokenAtPosition.getStart(file)) {
+        if (isToken(tokenAtPosition) && position > tokenAtPosition.getStart(file) && position < tokenAtPosition.getEnd()) {
             return tokenAtPosition;
         }
 

src/services/signatureHelp.ts

@@ -335,7 +335,12 @@ module ts.SignatureHelp {
 
     export function getSignatureHelpItems(sourceFile: SourceFile, position: number, typeInfoResolver: TypeChecker, cancellationToken: CancellationTokenObject): SignatureHelpItems {
         // Decide whether to show signature help
-        var startingToken = ServicesSyntaxUtilities.findTokenOnLeftOfPosition(sourceFile, position);
+        var startingToken = findTokenOnLeftOfPosition(sourceFile, position);
+        if (!startingToken) {
+            // We are at the beginning of the file
+            return undefined;
+        }
+
         var argumentList = getContainingArgumentList(startingToken);
         cancellationToken.throwIfCancellationRequested();
 
@@ -390,7 +395,7 @@ module ts.SignatureHelp {
                 return undefined;
             }
 
-            return ServicesSyntaxUtilities.findContainingList(node);
+            return findContainingList(node);
         }
 
         function getContainingArgumentList(node: Node): Node {
@@ -458,7 +463,7 @@ module ts.SignatureHelp {
     }
 
     export function getSignatureHelpCurrentArgumentState(sourceFile: SourceFile, position: number, applicableSpanStart: number): SignatureHelpState {
-        var tokenPrecedingSpanStart = ServicesSyntaxUtilities.findPrecedingToken(applicableSpanStart, sourceFile);
+        var tokenPrecedingSpanStart = findPrecedingToken(applicableSpanStart, sourceFile);
         if (!tokenPrecedingSpanStart) {
             return undefined;
         }
@@ -468,7 +473,7 @@ module ts.SignatureHelp {
             return undefined;
         }
 
-        var tokenPrecedingCurrentPosition = ServicesSyntaxUtilities.findPrecedingToken(position, sourceFile);
+        var tokenPrecedingCurrentPosition = findPrecedingToken(position, sourceFile);
         var call = <CallExpression>tokenPrecedingSpanStart.parent;
         Debug.assert(call.kind === SyntaxKind.CallExpression || call.kind === SyntaxKind.NewExpression, "wrong call kind " + SyntaxKind[call.kind]);
         if (tokenPrecedingCurrentPosition.kind === SyntaxKind.CloseParenToken || tokenPrecedingCurrentPosition.kind === SyntaxKind.GreaterThanToken) {
@@ -492,7 +497,7 @@ module ts.SignatureHelp {
             return new SignatureHelpState(/*argumentIndex*/ 0, argumentCount);
         }
 
-        var indexOfNodeContainingPosition = ServicesSyntaxUtilities.findListItemIndexContainingPosition(argumentListOrTypeArgumentList, position);
+        var indexOfNodeContainingPosition = findListItemIndexContainingPosition(argumentListOrTypeArgumentList, position);
 
         // indexOfNodeContainingPosition checks that position is between pos and end of each child, so it is
         // possible that we are to the right of all children. Assume that we are still within