Add language service support for const

src/services/navigationBar.ts

@@ -233,7 +233,12 @@ module ts.NavigationBar {
                     return createItem(node, getTextOfNode((<FunctionDeclaration>node).name), ts.ScriptElementKind.functionElement);
 
                 case SyntaxKind.VariableDeclaration:
-                    return createItem(node, getTextOfNode((<VariableDeclaration>node).name), ts.ScriptElementKind.variableElement);
+                    if (node.flags & NodeFlags.Const) {
+                        return createItem(node, getTextOfNode((<VariableDeclaration>node).name), ts.ScriptElementKind.constantElement);
+                    }
+                    else {
+                        return createItem(node, getTextOfNode((<VariableDeclaration>node).name), ts.ScriptElementKind.variableElement);
+                    }
 
                 case SyntaxKind.Constructor:
                     return createItem(node, "constructor", ts.ScriptElementKind.constructorImplementationElement);

src/services/services.ts

@@ -1235,7 +1235,9 @@ module ts {
 
         static label = "label";
 
-        static alias = "alias"
+        static alias = "alias";
+
+        static constantElement = "constant";
     }
 
     export class ScriptElementKindModifier {
@@ -2720,6 +2722,9 @@ module ts {
                 if (isFirstDeclarationOfSymbolParameter(symbol)) {
                     return ScriptElementKind.parameterElement;
                 }
+                else if(forEach(symbol.declarations, d => d.flags & NodeFlags.Const)) {
+                    return ScriptElementKind.constantElement;
+                }
                 return isLocalVariableOrFunction(symbol) ? ScriptElementKind.localVariableElement : ScriptElementKind.variableElement;
             }
             if (flags & SymbolFlags.Function) return isLocalVariableOrFunction(symbol) ? ScriptElementKind.localFunctionElement : ScriptElementKind.functionElement;
@@ -2751,7 +2756,7 @@ module ts {
                 case SyntaxKind.ClassDeclaration: return ScriptElementKind.classElement;
                 case SyntaxKind.InterfaceDeclaration: return ScriptElementKind.interfaceElement;
                 case SyntaxKind.EnumDeclaration: return ScriptElementKind.enumElement;
-                case SyntaxKind.VariableDeclaration: return ScriptElementKind.variableElement;
+                case SyntaxKind.VariableDeclaration: return node.flags & NodeFlags.Const ? ScriptElementKind.constantElement: ScriptElementKind.variableElement;
                 case SyntaxKind.FunctionDeclaration: return ScriptElementKind.functionElement;
                 case SyntaxKind.GetAccessor: return ScriptElementKind.memberGetAccessorElement;
                 case SyntaxKind.SetAccessor: return ScriptElementKind.memberSetAccessorElement;
@@ -2840,6 +2845,7 @@ module ts {
                             switch (symbolKind) {
                                 case ScriptElementKind.memberVariableElement:
                                 case ScriptElementKind.variableElement:
+                                case ScriptElementKind.constantElement:
                                 case ScriptElementKind.parameterElement:
                                 case ScriptElementKind.localVariableElement:
                                     // If it is call or construct signature of lambda's write type name

tests/cases/fourslash/completionEntryForConst.ts

@@ -0,0 +1,7 @@
+///<reference path="fourslash.ts" />
+
+////const c = "s";
+/////**/
+
+goTo.marker();
+verify.completionListContains("c", /*text*/ undefined, /*documentation*/ undefined, "constant");

tests/cases/fourslash/navbar_const.ts

@@ -0,0 +1,13 @@
+/// <reference path="fourslash.ts" />
+
+//// {| "itemName": "c", "kind": "constant", "parentName": "" |}const c = 0;
+
+test.markers().forEach(marker => {
+    verify.getScriptLexicalStructureListContains(
+        marker.data.itemName,
+        marker.data.kind,
+        marker.fileName,
+        marker.data.parentName,
+        marker.data.isAdditionalRange,
+        marker.position);
+});

tests/cases/fourslash/quickInfoForConstDeclaration.ts

@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts' />
+
+////const /**/c = 0 ;
+
+goTo.marker();
+verify.quickInfoIs("(constant) c: number");