TypeScript/doc/spec/Grammar.md

Grammar

This appendix contains a summary of the grammar found in the main document. As described in section [#grammar-conventions], the TypeScript grammar is a superset of the grammar defined in the ECMAScript 2015 Language Specification (specifically, the ECMA-262 Standard, 6th Edition) and this appendix lists only productions that are new or modified from the ECMAScript grammar.

Types

  TypeParameters:    < TypeParameterList >

  TypeParameterList:    TypeParameter    TypeParameterList , TypeParameter

  TypeParameter:    BindingIdentifier Constraint_opt

  Constraint:    extends Type

  TypeArguments:    < TypeArgumentList >

  TypeArgumentList:    TypeArgument    TypeArgumentList , TypeArgument

  TypeArgument:    Type

  Type:    UnionOrIntersectionOrPrimaryType    FunctionType    ConstructorType

  UnionOrIntersectionOrPrimaryType:    UnionType    IntersectionOrPrimaryType

  IntersectionOrPrimaryType:    IntersectionType    PrimaryType

  PrimaryType:    ParenthesizedType    PredefinedType    TypeReference    ObjectType    ArrayType    TupleType    TypeQuery    ThisType

  ParenthesizedType:    ( Type )

  PredefinedType:    any    number    boolean    string    symbol    void

  TypeReference:    TypeName [no LineTerminator here] TypeArguments_opt

  TypeName:    IdentifierReference    NamespaceName . IdentifierReference

  NamespaceName:    IdentifierReference    NamespaceName . IdentifierReference

  ObjectType:    { TypeBody_opt }

  TypeBody:    TypeMemberList ;_opt    TypeMemberList ,_opt

  TypeMemberList:    TypeMember    TypeMemberList ; TypeMember    TypeMemberList , TypeMember

  TypeMember:    PropertySignature    CallSignature    ConstructSignature    IndexSignature    MethodSignature

  ArrayType:    PrimaryType [no LineTerminator here] [ ]

  TupleType:    [ TupleElementTypes ]

  TupleElementTypes:    TupleElementType    TupleElementTypes , TupleElementType

  TupleElementType:    Type

  UnionType:    UnionOrIntersectionOrPrimaryType | IntersectionOrPrimaryType

  IntersectionType:    IntersectionOrPrimaryType & PrimaryType

  FunctionType:    TypeParameters_opt ( ParameterList_opt ) => Type

  ConstructorType:    new TypeParameters_opt ( ParameterList_opt ) => Type

  TypeQuery:    typeof TypeQueryExpression

  TypeQueryExpression:    IdentifierReference    TypeQueryExpression . IdentifierName

  ThisType:    this

  PropertySignature:    PropertyName ?_opt TypeAnnotation_opt

  PropertyName:    IdentifierName    StringLiteral    NumericLiteral

  TypeAnnotation:    : Type

  CallSignature:    TypeParameters_opt ( ParameterList_opt ) TypeAnnotation_opt

  ParameterList:    RequiredParameterList    OptionalParameterList    RestParameter    RequiredParameterList , OptionalParameterList    RequiredParameterList , RestParameter    OptionalParameterList , RestParameter    RequiredParameterList , OptionalParameterList , RestParameter

  RequiredParameterList:    RequiredParameter    RequiredParameterList , RequiredParameter

  RequiredParameter:    AccessibilityModifier_opt BindingIdentifierOrPattern TypeAnnotation_opt    BindingIdentifier : StringLiteral

  AccessibilityModifier:    public    private    protected

  BindingIdentifierOrPattern:    BindingIdentifier    BindingPattern

  OptionalParameterList:    OptionalParameter    OptionalParameterList , OptionalParameter

  OptionalParameter:    AccessibilityModifier_opt BindingIdentifierOrPattern ? TypeAnnotation_opt    AccessibilityModifier_opt BindingIdentifierOrPattern TypeAnnotation_opt Initializer    BindingIdentifier ? : StringLiteral

  RestParameter:    ... BindingIdentifier TypeAnnotation_opt

  ConstructSignature:    new TypeParameters_opt ( ParameterList_opt ) TypeAnnotation_opt

  IndexSignature:    [ BindingIdentifier : string ] TypeAnnotation    [ BindingIdentifier : number ] TypeAnnotation

  MethodSignature:    PropertyName ?_opt CallSignature

  TypeAliasDeclaration:    type BindingIdentifier TypeParameters_opt = Type ;

Expressions

  PropertyDefinition: ( Modified )    IdentifierReference    CoverInitializedName    PropertyName : AssignmentExpression    PropertyName CallSignature { FunctionBody }    GetAccessor    SetAccessor

  GetAccessor:    get PropertyName ( ) TypeAnnotation_opt { FunctionBody }

  SetAccessor:    set PropertyName ( BindingIdentifierOrPattern TypeAnnotation_opt ) { FunctionBody }

  FunctionExpression: ( Modified )    function BindingIdentifier_opt CallSignature { FunctionBody }

  ArrowFormalParameters: ( Modified )    CallSignature

  Arguments: ( Modified )    TypeArguments_opt ( ArgumentList_opt )

  UnaryExpression: ( Modified )    …    < Type > UnaryExpression

Statements

  Declaration: ( Modified )    …    InterfaceDeclaration    TypeAliasDeclaration    EnumDeclaration

  VariableDeclaration: ( Modified )    SimpleVariableDeclaration    DestructuringVariableDeclaration

  SimpleVariableDeclaration:    BindingIdentifier TypeAnnotation_opt Initializer_opt

  DestructuringVariableDeclaration:    BindingPattern TypeAnnotation_opt Initializer

  LexicalBinding: ( Modified )    SimpleLexicalBinding    DestructuringLexicalBinding

  SimpleLexicalBinding:    BindingIdentifier TypeAnnotation_opt Initializer_opt

  DestructuringLexicalBinding:    BindingPattern TypeAnnotation_opt Initializer_opt

Functions

  FunctionDeclaration: ( Modified )    function BindingIdentifier_opt CallSignature { FunctionBody }    function BindingIdentifier_opt CallSignature ;

Interfaces

  InterfaceDeclaration:    interface BindingIdentifier TypeParameters_opt InterfaceExtendsClause_opt ObjectType

  InterfaceExtendsClause:    extends ClassOrInterfaceTypeList

  ClassOrInterfaceTypeList:    ClassOrInterfaceType    ClassOrInterfaceTypeList , ClassOrInterfaceType

  ClassOrInterfaceType:    TypeReference

Classes

  ClassDeclaration: ( Modified )    class BindingIdentifier_opt TypeParameters_opt ClassHeritage { ClassBody }

  ClassHeritage: ( Modified )    ClassExtendsClause_opt ImplementsClause_opt

  ClassExtendsClause:    extends  ClassType

  ClassType:    TypeReference

  ImplementsClause:    implements ClassOrInterfaceTypeList

  ClassElement: ( Modified )    ConstructorDeclaration    PropertyMemberDeclaration    IndexMemberDeclaration

  ConstructorDeclaration:    AccessibilityModifier_opt constructor ( ParameterList_opt ) { FunctionBody }    AccessibilityModifier_opt constructor ( ParameterList_opt ) ;

  PropertyMemberDeclaration:    MemberVariableDeclaration    MemberFunctionDeclaration    MemberAccessorDeclaration

  MemberVariableDeclaration:    AccessibilityModifier_opt static_opt PropertyName TypeAnnotation_opt Initializer_opt ;

  MemberFunctionDeclaration:    AccessibilityModifier_opt static_opt PropertyName CallSignature { FunctionBody }    AccessibilityModifier_opt static_opt PropertyName CallSignature ;

  MemberAccessorDeclaration:    AccessibilityModifier_opt static_opt GetAccessor    AccessibilityModifier_opt static_opt SetAccessor

  IndexMemberDeclaration:    IndexSignature ;

Enums

  EnumDeclaration:    const_opt enum BindingIdentifier { EnumBody_opt }

  EnumBody:    EnumMemberList ,_opt

  EnumMemberList:    EnumMember    EnumMemberList , EnumMember

  EnumMember:    PropertyName    PropertyName = EnumValue

  EnumValue:    AssignmentExpression

Namespaces

  NamespaceDeclaration:    namespace IdentifierPath { NamespaceBody }

  IdentifierPath:    BindingIdentifier    IdentifierPath . BindingIdentifier

  NamespaceBody:    NamespaceElements_opt

  NamespaceElements:    NamespaceElement    NamespaceElements NamespaceElement

  NamespaceElement:    Statement    LexicalDeclaration    FunctionDeclaration    GeneratorDeclaration    ClassDeclaration    InterfaceDeclaration    TypeAliasDeclaration    EnumDeclaration    NamespaceDeclaration    AmbientDeclaration    ImportAliasDeclaration    ExportNamespaceElement

  ExportNamespaceElement:    export VariableStatement    export LexicalDeclaration    export FunctionDeclaration    export GeneratorDeclaration    export ClassDeclaration    export InterfaceDeclaration    export TypeAliasDeclaration    export EnumDeclaration    export NamespaceDeclaration    export AmbientDeclaration    export ImportAliasDeclaration

  ImportAliasDeclaration:    import BindingIdentifier = EntityName ;

  EntityName:    NamespaceName    NamespaceName . IdentifierReference

Scripts and Modules

  SourceFile:    ImplementationSourceFile    DeclarationSourceFile

  ImplementationSourceFile:    ImplementationScript    ImplementationModule

  DeclarationSourceFile:    DeclarationScript    DeclarationModule

  ImplementationScript:    ImplementationScriptElements_opt

  ImplementationScriptElements:    ImplementationScriptElement    ImplementationScriptElements ImplementationScriptElement

  ImplementationScriptElement:    ImplementationElement    AmbientModuleDeclaration

  ImplementationElement:    Statement    LexicalDeclaration    FunctionDeclaration    GeneratorDeclaration    ClassDeclaration    InterfaceDeclaration    TypeAliasDeclaration    EnumDeclaration    NamespaceDeclaration    AmbientDeclaration    ImportAliasDeclaration

  DeclarationScript:    DeclarationScriptElements_opt

  DeclarationScriptElements:    DeclarationScriptElement    DeclarationScriptElements DeclarationScriptElement

  DeclarationScriptElement:    DeclarationElement    AmbientModuleDeclaration

  DeclarationElement:    InterfaceDeclaration    TypeAliasDeclaration    NamespaceDeclaration    AmbientDeclaration    ImportAliasDeclaration

  ImplementationModule:    ImplementationModuleElements_opt

  ImplementationModuleElements:    ImplementationModuleElement    ImplementationModuleElements ImplementationModuleElement

  ImplementationModuleElement:    ImplementationElement    ImportDeclaration    ImportAliasDeclaration    ImportRequireDeclaration    ExportImplementationElement    ExportDefaultImplementationElement    ExportListDeclaration    ExportAssignment

  DeclarationModule:    DeclarationModuleElements_opt

  DeclarationModuleElements:    DeclarationModuleElement    DeclarationModuleElements DeclarationModuleElement

  DeclarationModuleElement:    DeclarationElement    ImportDeclaration    ImportAliasDeclaration    ExportDeclarationElement    ExportDefaultDeclarationElement    ExportListDeclaration    ExportAssignment

  ImportRequireDeclaration:    import BindingIdentifier = require ( StringLiteral ) ;

  ExportImplementationElement:    export VariableStatement    export LexicalDeclaration    export FunctionDeclaration    export GeneratorDeclaration    export ClassDeclaration    export InterfaceDeclaration    export TypeAliasDeclaration    export EnumDeclaration    export NamespaceDeclaration    export AmbientDeclaration    export ImportAliasDeclaration

  ExportDeclarationElement:    export InterfaceDeclaration    export TypeAliasDeclaration    export AmbientDeclaration    export ImportAliasDeclaration

  ExportDefaultImplementationElement:    export default FunctionDeclaration    export default GeneratorDeclaration    export default ClassDeclaration    export default AssignmentExpression ;

  ExportDefaultDeclarationElement:    export default AmbientFunctionDeclaration    export default AmbientClassDeclaration    export default IdentifierReference ;

  ExportListDeclaration:    export * FromClause ;    export ExportClause FromClause ;    export ExportClause ;

  ExportAssignment:    export = IdentifierReference ;

Ambients

  AmbientDeclaration:    declare AmbientVariableDeclaration    declare AmbientFunctionDeclaration    declare AmbientClassDeclaration    declare AmbientEnumDeclaration    declare AmbientNamespaceDeclaration

  AmbientVariableDeclaration:    var AmbientBindingList ;    let AmbientBindingList ;    const AmbientBindingList ;

  AmbientBindingList:    AmbientBinding    AmbientBindingList , AmbientBinding

  AmbientBinding:    BindingIdentifier TypeAnnotation_opt

  AmbientFunctionDeclaration:    function BindingIdentifier CallSignature ;

  AmbientClassDeclaration:    class BindingIdentifier TypeParameters_opt ClassHeritage { AmbientClassBody }

  AmbientClassBody:    AmbientClassBodyElements_opt

  AmbientClassBodyElements:    AmbientClassBodyElement    AmbientClassBodyElements AmbientClassBodyElement

  AmbientClassBodyElement:    AmbientConstructorDeclaration    AmbientPropertyMemberDeclaration    IndexSignature

  AmbientConstructorDeclaration:    constructor ( ParameterList_opt ) ;

  AmbientPropertyMemberDeclaration:    AccessibilityModifier_opt static_opt PropertyName TypeAnnotation_opt ;    AccessibilityModifier_opt static_opt PropertyName CallSignature ;

  AmbientEnumDeclaration:    EnumDeclaration

  AmbientNamespaceDeclaration:    namespace IdentifierPath { AmbientNamespaceBody }

  AmbientNamespaceBody:    AmbientNamespaceElements_opt

  AmbientNamespaceElements:    AmbientNamespaceElement    AmbientNamespaceElements AmbientNamespaceElement

  AmbientNamespaceElement:    export_opt AmbientVariableDeclaration    export_opt AmbientLexicalDeclaration    export_opt AmbientFunctionDeclaration    export_opt AmbientClassDeclaration    export_opt InterfaceDeclaration    export_opt AmbientEnumDeclaration    export_opt AmbientNamespaceDeclaration    export_opt ImportAliasDeclaration

  AmbientModuleDeclaration:    declare module StringLiteral {  DeclarationModule }