Parsing, binding, checking of export default with function/class

ahejlsberg · ahejlsberg · commit 9af8ae43866e · 2015-03-03T15:09:40.000-08:00
diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
@@ -112,10 +112,13 @@ module ts {
                     return "__new";
                 case SyntaxKind.IndexSignature:
                     return "__index";
-                case SyntaxKind.ExportAssignment:
-                    return "default";
                 case SyntaxKind.ExportDeclaration:
                     return "__export";
+                case SyntaxKind.ExportAssignment:
+                    return "default";
+                case SyntaxKind.FunctionDeclaration:
+                case SyntaxKind.ClassDeclaration:
+                    return node.flags & NodeFlags.Default ? "default" : undefined;
             }
         }
 
@@ -126,7 +129,7 @@ module ts {
         function declareSymbol(symbols: SymbolTable, parent: Symbol, node: Declaration, includes: SymbolFlags, excludes: SymbolFlags): Symbol {
             Debug.assert(!hasDynamicName(node));
 
-            var name = getDeclarationName(node);
+            var name = node.flags & NodeFlags.Default && parent ? "default" : getDeclarationName(node);
             if (name !== undefined) {
                 var symbol = hasProperty(symbols, name) ? symbols[name] : (symbols[name] = createSymbol(0, name));
                 if (symbol.flags & excludes) {
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -8268,7 +8268,7 @@ module ts {
             // Do not use hasDynamicName here, because that returns false for well known symbols.
             // We want to perform checkComputedPropertyName for all computed properties, including
             // well known symbols.
-            if (node.name.kind === SyntaxKind.ComputedPropertyName) {
+            if (node.name && node.name.kind === SyntaxKind.ComputedPropertyName) {
                 // This check will account for methods in class/interface declarations,
                 // as well as accessors in classes/object literals
                 checkComputedPropertyName(<ComputedPropertyName>node.name);
@@ -8998,10 +8998,12 @@ module ts {
             // Grammar checking
             checkGrammarClassDeclarationHeritageClauses(node);
 
-            checkTypeNameIsReserved(node.name, Diagnostics.Class_name_cannot_be_0);
+            if (node.name) {
+                checkTypeNameIsReserved(node.name, Diagnostics.Class_name_cannot_be_0);
+                checkCollisionWithCapturedThisVariable(node, node.name);
+                checkCollisionWithRequireExportsInGeneratedCode(node, node.name);
+            }
             checkTypeParameters(node.typeParameters);
-            checkCollisionWithCapturedThisVariable(node, node.name);
-            checkCollisionWithRequireExportsInGeneratedCode(node, node.name);
             checkExportsOnMergedDeclarations(node);
             var symbol = getSymbolOfNode(node);
             var type = <InterfaceType>getDeclaredTypeOfSymbol(symbol);
@@ -9014,9 +9016,9 @@ module ts {
             if (type.baseTypes.length) {
                 if (produceDiagnostics) {
                     var baseType = type.baseTypes[0];
-                    checkTypeAssignableTo(type, baseType, node.name, Diagnostics.Class_0_incorrectly_extends_base_class_1);
+                    checkTypeAssignableTo(type, baseType, node.name || node, Diagnostics.Class_0_incorrectly_extends_base_class_1);
                     var staticBaseType = getTypeOfSymbol(baseType.symbol);
-                    checkTypeAssignableTo(staticType, getTypeWithoutConstructors(staticBaseType), node.name,
+                    checkTypeAssignableTo(staticType, getTypeWithoutConstructors(staticBaseType), node.name || node,
                         Diagnostics.Class_static_side_0_incorrectly_extends_base_class_static_side_1);
                     if (baseType.symbol !== resolveEntityName(baseTypeNode.typeName, SymbolFlags.Value)) {
                         error(baseTypeNode, Diagnostics.Type_name_0_in_extends_clause_does_not_reference_constructor_function_for_0, typeToString(baseType));
@@ -9038,7 +9040,7 @@ module ts {
                         if (t !== unknownType) {
                             var declaredType = (t.flags & TypeFlags.Reference) ? (<TypeReference>t).target : t;
                             if (declaredType.flags & (TypeFlags.Class | TypeFlags.Interface)) {
-                                checkTypeAssignableTo(type, t, node.name, Diagnostics.Class_0_incorrectly_implements_interface_1);
+                                checkTypeAssignableTo(type, t, node.name || node, Diagnostics.Class_0_incorrectly_implements_interface_1);
                             }
                             else {
                                 error(typeRefNode, Diagnostics.A_class_may_only_implement_another_class_or_interface);
@@ -10414,6 +10416,10 @@ module ts {
 
             function generateNames(node: Node) {
                 switch (node.kind) {
+                    case SyntaxKind.FunctionDeclaration:
+                    case SyntaxKind.ClassDeclaration:
+                        generateNameForFunctionOrClassDeclaration(<Declaration>node);
+                        break;
                     case SyntaxKind.ModuleDeclaration:
                         generateNameForModuleOrEnum(<ModuleDeclaration>node);
                         generateNames((<ModuleDeclaration>node).body);
@@ -10427,6 +10433,9 @@ module ts {
                     case SyntaxKind.ExportDeclaration:
                         generateNameForExportDeclaration(<ExportDeclaration>node);
                         break;
+                    case SyntaxKind.ExportAssignment:
+                        generateNameForExportAssignment(<ExportAssignment>node);
+                        break;
                     case SyntaxKind.SourceFile:
                     case SyntaxKind.ModuleBlock:
                         forEach((<SourceFile | ModuleBlock>node).statements, generateNames);
@@ -10464,6 +10473,12 @@ module ts {
                 getNodeLinks(node).generatedName = unescapeIdentifier(name);
             }
 
+            function generateNameForFunctionOrClassDeclaration(node: Declaration) {
+                if (!node.name) {
+                    assignGeneratedName(node, makeUniqueName("default"));
+                }
+            }
+
             function generateNameForModuleOrEnum(node: ModuleDeclaration | EnumDeclaration) {
                 if (node.name.kind === SyntaxKind.Identifier) {
                     var name = node.name.text;
@@ -10490,9 +10505,15 @@ module ts {
                     generateNameForImportOrExportDeclaration(node);
                 }
             }
+
+            function generateNameForExportAssignment(node: ExportAssignment) {
+                if (node.expression.kind !== SyntaxKind.Identifier) {
+                    assignGeneratedName(node, makeUniqueName("default"));
+                }
+            }
         }
 
-        function getGeneratedNameForNode(node: ModuleDeclaration | EnumDeclaration | ImportDeclaration | ExportDeclaration) {
+        function getGeneratedNameForNode(node: Node) {
             var links = getNodeLinks(node);
             if (!links.generatedName) {
                 getGeneratedNamesForSourceFile(getSourceFile(node));
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
@@ -1580,7 +1580,7 @@ module ts {
             var tempParameters: Identifier[];
             var externalImports: ExternalImportInfo[];
             var exportSpecifiers: Map<ExportSpecifier[]>;
-            var exportDefault: ExportAssignment | ExportSpecifier;
+            var exportDefault: FunctionDeclaration | ClassDeclaration | ExportAssignment | ExportSpecifier;
 
             /** write emitted output to disk*/
             var writeEmittedFiles = writeJavaScriptFile;
@@ -3912,7 +3912,7 @@ module ts {
                     emitExpressionFunctionBody(node, <Expression>node.body);
                 }
 
-                if (node.flags & NodeFlags.Export) {
+                if (node.flags & NodeFlags.Export && !(node.flags & NodeFlags.Default)) {
                     writeLine();
                     emitStart(node);
                     emitModuleMemberName(node);
@@ -4243,11 +4243,10 @@ module ts {
                 emitMemberFunctions(node);
                 emitMemberAssignments(node, NodeFlags.Static);
                 writeLine();
-                function emitClassReturnStatement() {
+                emitToken(SyntaxKind.CloseBraceToken, node.members.end, () => {
                     write("return ");
                     emitNode(node.name);
-                }
-                emitToken(SyntaxKind.CloseBraceToken, node.members.end, emitClassReturnStatement);
+                });
                 write(";");
                 decreaseIndent();
                 writeLine();
@@ -4260,7 +4259,7 @@ module ts {
                 }
                 write(");");
                 emitEnd(node);
-                if (node.flags & NodeFlags.Export) {
+                if (node.flags & NodeFlags.Export && !(node.flags & NodeFlags.Default)) {
                     writeLine();
                     emitStart(node);
                     emitModuleMemberName(node);
@@ -4269,7 +4268,7 @@ module ts {
                     emitEnd(node);
                     write(";");
                 }
-                if (languageVersion < ScriptTarget.ES6 && node.parent === currentSourceFile) {
+                if (languageVersion < ScriptTarget.ES6 && node.parent === currentSourceFile && node.name) {
                     emitExportMemberAssignments(node.name);
                 }
 
@@ -4680,6 +4679,11 @@ module ts {
                     else if (node.kind === SyntaxKind.ExportAssignment) {
                         exportDefault = exportDefault || <ExportAssignment>node;
                     }
+                    else if (node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.ClassDeclaration) {
+                        if (node.flags & NodeFlags.Export && node.flags & NodeFlags.Default) {
+                            exportDefault = exportDefault || <FunctionDeclaration | ClassDeclaration>node;
+                        }
+                    }
                     else {
                         var info = createExternalImportInfo(node);
                         if (info) {
@@ -4788,9 +4792,12 @@ module ts {
                     if (exportDefault.kind === SyntaxKind.ExportAssignment) {
                         emit((<ExportAssignment>exportDefault).expression);
                     }
-                    else {
+                    else if (exportDefault.kind === SyntaxKind.ExportSpecifier) {
                         emit((<ExportSpecifier>exportDefault).propertyName);
                     }
+                    else {
+                        emit((<Declaration>exportDefault).name);
+                    }
                     write(";");
                     emitEnd(exportDefault);
                 }
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
@@ -358,6 +358,7 @@ module ts {
             case SyntaxKind.ExportKeyword: return NodeFlags.Export;
             case SyntaxKind.DeclareKeyword: return NodeFlags.Ambient;
             case SyntaxKind.ConstKeyword: return NodeFlags.Const;
+            case SyntaxKind.DefaultKeyword: return NodeFlags.Default;
         }
         return 0;
     }
@@ -1501,11 +1502,13 @@ module ts {
             if (token === SyntaxKind.ExportKeyword) {
                 nextToken();
                 if (token === SyntaxKind.DefaultKeyword) {
-                    nextToken();
-                    return token === SyntaxKind.ClassKeyword || token === SyntaxKind.FunctionKeyword;
+                    return lookAhead(nextTokenIsClassOrFunction);
                 }
                 return token !== SyntaxKind.AsteriskToken && token !== SyntaxKind.OpenBraceToken && canFollowModifier();
             }
+            if (token === SyntaxKind.DefaultKeyword) {
+                return nextTokenIsClassOrFunction();
+            }
             nextToken();
             return canFollowModifier();
         }
@@ -1517,6 +1520,11 @@ module ts {
                 || isLiteralPropertyName();
         }
 
+        function nextTokenIsClassOrFunction(): boolean {
+            nextToken();
+            return token === SyntaxKind.ClassKeyword || token === SyntaxKind.FunctionKeyword;
+        }
+
         // True if positioned at the start of a list element
         function isListElement(parsingContext: ParsingContext, inErrorRecovery: boolean): boolean {
             var node = currentNode(parsingContext);
@@ -4323,7 +4331,7 @@ module ts {
             setModifiers(node, modifiers);
             parseExpected(SyntaxKind.FunctionKeyword);
             node.asteriskToken = parseOptionalToken(SyntaxKind.AsteriskToken);
-            node.name = parseIdentifier();
+            node.name = node.flags & NodeFlags.Default ? parseOptionalIdentifier() : parseIdentifier();
             fillSignature(SyntaxKind.ColonToken, /*yieldAndGeneratorParameterContext:*/ !!node.asteriskToken, /*requireCompleteParameterList:*/ false, node);
             node.body = parseFunctionBlockOrSemicolon(!!node.asteriskToken, Diagnostics.or_expected);
             return finishNode(node);
@@ -4499,7 +4507,7 @@ module ts {
             var node = <ClassDeclaration>createNode(SyntaxKind.ClassDeclaration, fullStart);
             setModifiers(node, modifiers);
             parseExpected(SyntaxKind.ClassKeyword);
-            node.name = parseIdentifier();
+            node.name = node.flags & NodeFlags.Default ? parseOptionalIdentifier() : parseIdentifier();
             node.typeParameters = parseTypeParameters();
             node.heritageClauses = parseHeritageClauses(/*isClassHeritageClause:*/ true);
 
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -298,14 +298,15 @@ module ts {
         Private =           0x00000020,  // Property/Method
         Protected =         0x00000040,  // Property/Method
         Static =            0x00000080,  // Property/Method
-        MultiLine =         0x00000100,  // Multi-line array or object literal
-        Synthetic =         0x00000200,  // Synthetic node (for full fidelity)
-        DeclarationFile =   0x00000400,  // Node is a .d.ts file
-        Let =               0x00000800,  // Variable declaration
-        Const =             0x00001000,  // Variable declaration
-        OctalLiteral =      0x00002000,
-
-        Modifier = Export | Ambient | Public | Private | Protected | Static,
+        Default =           0x00000100,  // Function/Class (export default declaration)
+        MultiLine =         0x00000200,  // Multi-line array or object literal
+        Synthetic =         0x00000400,  // Synthetic node (for full fidelity)
+        DeclarationFile =   0x00000800,  // Node is a .d.ts file
+        Let =               0x00001000,  // Variable declaration
+        Const =             0x00002000,  // Variable declaration
+        OctalLiteral =      0x00004000,
+
+        Modifier = Export | Ambient | Public | Private | Protected | Static | Default,
         AccessibilityModifier = Public | Private | Protected,
         BlockScoped = Let | Const
     }
@@ -1185,7 +1186,7 @@ module ts {
     }
 
     export interface EmitResolver {
-        getGeneratedNameForNode(node: ModuleDeclaration | EnumDeclaration | ImportDeclaration | ExportDeclaration): string;
+        getGeneratedNameForNode(node: Node): string;
         getExpressionNameSubstitution(node: Identifier): string;
         hasExportDefaultValue(node: SourceFile): boolean;
         isReferencedImportDeclaration(node: Node): boolean;
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
@@ -901,6 +901,7 @@ module ts {
             case SyntaxKind.ExportKeyword:
             case SyntaxKind.DeclareKeyword:
             case SyntaxKind.ConstKeyword:
+            case SyntaxKind.DefaultKeyword:
                 return true;
         }
         return false;

Original file line number	Diff line number	Diff line change
`@@ -901,6 +901,7 @@ module ts {`
`901`	`901`	`case SyntaxKind.ExportKeyword:`
`902`	`902`	`case SyntaxKind.DeclareKeyword:`
`903`	`903`	`case SyntaxKind.ConstKeyword:`
	`904`	`+ case SyntaxKind.DefaultKeyword:`
`904`	`905`	`return true;`
`905`	`906`	`}`
`906`	`907`	`return false;`