Merge pull request microsoft#14690 from Microsoft/clean_up_parser

Clean up code in parser

Author: Andy

src/compiler/parser.ts

@@ -1309,7 +1309,7 @@ namespace ts {
                 case ParsingContext.ObjectBindingElements:
                     return token() === SyntaxKind.OpenBracketToken || token() === SyntaxKind.DotDotDotToken || isLiteralPropertyName();
                 case ParsingContext.HeritageClauseElement:
-                    // If we see { } then only consume it as an expression if it is followed by , or {
+                    // If we see `{ ... }` then only consume it as an expression if it is followed by `,` or `{`
                     // That way we won't consume the body of a class in its heritage clause.
                     if (token() === SyntaxKind.OpenBraceToken) {
                         return lookAhead(isValidHeritageClauseObjectLiteral);
@@ -2113,7 +2113,7 @@ namespace ts {
             return finishNode(node);
         }
 
-        function parseTypeParameters(): NodeArray<TypeParameterDeclaration> {
+        function parseTypeParameters(): NodeArray<TypeParameterDeclaration> | undefined {
             if (token() === SyntaxKind.LessThanToken) {
                 return parseBracketedList(ParsingContext.TypeParameters, parseTypeParameter, SyntaxKind.LessThanToken, SyntaxKind.GreaterThanToken);
             }
@@ -2183,7 +2183,7 @@ namespace ts {
         }
 
         function fillSignature(
-            returnToken: SyntaxKind,
+            returnToken: SyntaxKind.ColonToken | SyntaxKind.EqualsGreaterThanToken,
             yieldContext: boolean,
             awaitContext: boolean,
             requireCompleteParameterList: boolean,
@@ -2373,14 +2373,14 @@ namespace ts {
         }
 
         function isTypeMemberStart(): boolean {
-            let idToken: SyntaxKind;
             // Return true if we have the start of a signature member
             if (token() === SyntaxKind.OpenParenToken || token() === SyntaxKind.LessThanToken) {
                 return true;
             }
+            let idToken: boolean;
             // Eat up all modifiers, but hold on to the last one in case it is actually an identifier
             while (isModifierKind(token())) {
-                idToken = token();
+                idToken = true;
                 nextToken();
             }
             // Index signatures and computed property names are type members
@@ -2389,7 +2389,7 @@ namespace ts {
             }
             // Try to get the first property-like token following all modifiers
             if (isLiteralPropertyName()) {
-                idToken = token();
+                idToken = true;
                 nextToken();
             }
             // If we were able to get any potential identifier, check that it is
@@ -2497,7 +2497,7 @@ namespace ts {
             return finishNode(node);
         }
 
-        function parseKeywordAndNoDot(): TypeNode {
+        function parseKeywordAndNoDot(): TypeNode | undefined {
             const node = parseTokenNode<TypeNode>();
             return token() === SyntaxKind.DotToken ? undefined : node;
         }
@@ -2635,7 +2635,7 @@ namespace ts {
             return parseArrayTypeOrHigher();
         }
 
-        function parseUnionOrIntersectionType(kind: SyntaxKind, parseConstituentType: () => TypeNode, operator: SyntaxKind): TypeNode {
+        function parseUnionOrIntersectionType(kind: SyntaxKind.UnionType | SyntaxKind.IntersectionType, parseConstituentType: () => TypeNode, operator: SyntaxKind.BarToken | SyntaxKind.AmpersandToken): TypeNode {
             parseOptional(operator);
             let type = parseConstituentType();
             if (token() === operator) {
@@ -5281,8 +5281,8 @@ namespace ts {
          *
          * In such situations, 'permitInvalidConstAsModifier' should be set to true.
          */
-        function parseModifiers(permitInvalidConstAsModifier?: boolean): NodeArray<Modifier> {
-            let modifiers: NodeArray<Modifier>;
+        function parseModifiers(permitInvalidConstAsModifier?: boolean): NodeArray<Modifier> | undefined {
+            let modifiers: NodeArray<Modifier> | undefined;
             while (true) {
                 const modifierStart = scanner.getStartPos();
                 const modifierKind = token();
@@ -5422,7 +5422,7 @@ namespace ts {
             return token() === SyntaxKind.ImplementsKeyword && lookAhead(nextTokenIsIdentifierOrKeyword);
         }
 
-        function parseHeritageClauses(): NodeArray<HeritageClause> {
+        function parseHeritageClauses(): NodeArray<HeritageClause> | undefined {
             // ClassTail[Yield,Await] : (Modified) See 14.5
             //      ClassHeritage[?Yield,?Await]opt { ClassBody[?Yield,?Await]opt }
 
@@ -5433,7 +5433,7 @@ namespace ts {
             return undefined;
         }
 
-        function parseHeritageClause() {
+        function parseHeritageClause(): HeritageClause | undefined {
             if (token() === SyntaxKind.ExtendsKeyword || token() === SyntaxKind.ImplementsKeyword) {
                 const node = <HeritageClause>createNode(SyntaxKind.HeritageClause);
                 node.token = token();
@@ -5459,7 +5459,7 @@ namespace ts {
             return token() === SyntaxKind.ExtendsKeyword || token() === SyntaxKind.ImplementsKeyword;
         }
 
-        function parseClassMembers() {
+        function parseClassMembers(): NodeArray<ClassElement> {
             return parseList(ParsingContext.ClassMembers, parseClassElement);
         }
 
@@ -5618,17 +5618,7 @@ namespace ts {
             if (isIdentifier()) {
                 identifier = parseIdentifier();
                 if (token() !== SyntaxKind.CommaToken && token() !== SyntaxKind.FromKeyword) {
-                    // ImportEquals declaration of type:
-                    // import x = require("mod"); or
-                    // import x = M.x;
-                    const importEqualsDeclaration = <ImportEqualsDeclaration>createNode(SyntaxKind.ImportEqualsDeclaration, fullStart);
-                    importEqualsDeclaration.decorators = decorators;
-                    importEqualsDeclaration.modifiers = modifiers;
-                    importEqualsDeclaration.name = identifier;
-                    parseExpected(SyntaxKind.EqualsToken);
-                    importEqualsDeclaration.moduleReference = parseModuleReference();
-                    parseSemicolon();
-                    return addJSDocComment(finishNode(importEqualsDeclaration));
+                    return parseImportEqualsDeclaration(fullStart, decorators, modifiers, identifier);
                 }
             }
 
@@ -5652,6 +5642,17 @@ namespace ts {
             return finishNode(importDeclaration);
         }
 
+        function parseImportEqualsDeclaration(fullStart: number, decorators: NodeArray<Decorator>, modifiers: NodeArray<Modifier>, identifier: ts.Identifier): ImportEqualsDeclaration {
+            const importEqualsDeclaration = <ImportEqualsDeclaration>createNode(SyntaxKind.ImportEqualsDeclaration, fullStart);
+            importEqualsDeclaration.decorators = decorators;
+            importEqualsDeclaration.modifiers = modifiers;
+            importEqualsDeclaration.name = identifier;
+            parseExpected(SyntaxKind.EqualsToken);
+            importEqualsDeclaration.moduleReference = parseModuleReference();
+            parseSemicolon();
+            return addJSDocComment(finishNode(importEqualsDeclaration));
+        }
+
         function parseImportClause(identifier: Identifier, fullStart: number) {
             // ImportClause:
             //  ImportedDefaultBinding

src/compiler/types.ts

@@ -1813,7 +1813,7 @@ namespace ts {
         kind: SyntaxKind.ModuleDeclaration;
         parent?: ModuleBody | SourceFile;
         name: ModuleName;
-        body?: ModuleBody | JSDocNamespaceDeclaration | Identifier;
+        body?: ModuleBody | JSDocNamespaceDeclaration;
     }
 
     export type NamespaceBody = ModuleBlock | NamespaceDeclaration;
@@ -1838,6 +1838,11 @@ namespace ts {
 
     export type ModuleReference = EntityName | ExternalModuleReference;
 
+    /**
+     * One of:
+     * - import x = require("mod");
+     * - import x = M.x;
+     */
     export interface ImportEqualsDeclaration extends DeclarationStatement {
         kind: SyntaxKind.ImportEqualsDeclaration;
         parent?: SourceFile | ModuleBlock;
@@ -1889,7 +1894,6 @@ namespace ts {
     export interface NamespaceExportDeclaration extends DeclarationStatement {
         kind: SyntaxKind.NamespaceExportDeclaration;
         name: Identifier;
-        moduleReference: LiteralLikeNode;
     }
 
     export interface ExportDeclaration extends DeclarationStatement {