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Appendix B -- Grammar Summary.md

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B. Appendix: Grammar Summary

Source Text

SourceCharacter ::

  • "U+0009"
  • "U+000A"
  • "U+000D"
  • "U+0020–U+FFFF"

Ignored Tokens

Ignored ::

  • UnicodeBOM
  • WhiteSpace
  • LineTerminator
  • Comment
  • Comma

UnicodeBOM :: "Byte Order Mark (U+FEFF)"

WhiteSpace ::

  • "Horizontal Tab (U+0009)"
  • "Space (U+0020)"

LineTerminator ::

  • "New Line (U+000A)"
  • "Carriage Return (U+000D)" [lookahead != "New Line (U+000A)"]
  • "Carriage Return (U+000D)" "New Line (U+000A)"

Comment :: # CommentChar* [lookahead != CommentChar]

CommentChar :: SourceCharacter but not LineTerminator

Comma :: ,

Lexical Tokens

Token ::

  • Punctuator
  • Name
  • IntValue
  • FloatValue
  • StringValue

Punctuator :: one of ! $ & ( ) ... : = @ [ ] { | }

Name ::

  • NameStart NameContinue* [lookahead != NameContinue]

NameStart ::

  • Letter
  • _

NameContinue ::

  • Letter
  • Digit
  • _

Letter :: one of A B C D E F G H I J K L M N O P Q R S T U V W X Y Z a b c d e f g h i j k l m n o p q r s t u v w x y z

Digit :: one of 0 1 2 3 4 5 6 7 8 9

IntValue :: IntegerPart [lookahead != {Digit, ., NameStart}]

IntegerPart ::

  • NegativeSign? 0
  • NegativeSign? NonZeroDigit Digit*

NegativeSign :: -

NonZeroDigit :: Digit but not 0

FloatValue ::

  • IntegerPart FractionalPart ExponentPart [lookahead != {Digit, ., NameStart}]
  • IntegerPart FractionalPart [lookahead != {Digit, ., NameStart}]
  • IntegerPart ExponentPart [lookahead != {Digit, ., NameStart}]

FractionalPart :: . Digit+

ExponentPart :: ExponentIndicator Sign? Digit+

ExponentIndicator :: one of e E

Sign :: one of + -

StringValue ::

  • "" [lookahead != "]
  • " StringCharacter+ "
  • """ BlockStringCharacter* """

StringCharacter ::

  • SourceCharacter but not " or \ or LineTerminator
  • \u EscapedUnicode
  • \ EscapedCharacter

EscapedUnicode :: /[0-9A-Fa-f]{4}/

EscapedCharacter :: one of " \ / b f n r t

BlockStringCharacter ::

  • SourceCharacter but not """ or \"""
  • \"""

Note: Block string values are interpreted to exclude blank initial and trailing lines and uniform indentation with {BlockStringValue()}.

Document Syntax

Document : Definition+

Definition :

  • ExecutableDefinition
  • TypeSystemDefinition
  • TypeSystemExtension

ExecutableDefinition :

  • OperationDefinition
  • FragmentDefinition

OperationDefinition :

  • OperationType Name? VariableDefinitions? Directives? SelectionSet
  • SelectionSet

OperationType : one of query mutation subscription

SelectionSet : { Selection+ }

Selection :

  • Field
  • FragmentSpread
  • InlineFragment

Field : Alias? Name Arguments? Directives? SelectionSet?

Alias : Name :

Arguments[Const] : ( Argument[?Const]+ )

Argument[Const] : Name : Value[?Const]

FragmentSpread : ... FragmentName Directives?

InlineFragment : ... TypeCondition? Directives? SelectionSet

FragmentDefinition : fragment FragmentName TypeCondition Directives? SelectionSet

FragmentName : Name but not on

TypeCondition : on NamedType

Value[Const] :

  • [~Const] Variable
  • IntValue
  • FloatValue
  • StringValue
  • BooleanValue
  • NullValue
  • EnumValue
  • ListValue[?Const]
  • ObjectValue[?Const]

BooleanValue : one of true false

NullValue : null

EnumValue : Name but not true, false or null

ListValue[Const] :

  • [ ]
  • [ Value[?Const]+ ]

ObjectValue[Const] :

  • { }
  • { ObjectField[?Const]+ }

ObjectField[Const] : Name : Value[?Const]

VariableDefinitions : ( VariableDefinition+ )

VariableDefinition : Variable : Type DefaultValue? Directives[Const]?

Variable : $ Name

DefaultValue : = Value[Const]

Type :

  • NamedType
  • ListType
  • NonNullType

NamedType : Name

ListType : [ Type ]

NonNullType :

  • NamedType !
  • ListType !

Directives[Const] : Directive[?Const]+

Directive[Const] : @ Name Arguments[?Const]?

TypeSystemDefinition :

  • SchemaDefinition
  • TypeDefinition
  • DirectiveDefinition

TypeSystemExtension :

  • SchemaExtension
  • TypeExtension

SchemaDefinition : schema Directives[Const]? { RootOperationTypeDefinition+ }

SchemaExtension :

  • extend schema Directives[Const]? { RootOperationTypeDefinition+ }
  • extend schema Directives[Const]

RootOperationTypeDefinition : OperationType : NamedType

Description : StringValue

TypeDefinition :

  • ScalarTypeDefinition
  • ObjectTypeDefinition
  • InterfaceTypeDefinition
  • UnionTypeDefinition
  • EnumTypeDefinition
  • InputObjectTypeDefinition

TypeExtension :

  • ScalarTypeExtension
  • ObjectTypeExtension
  • InterfaceTypeExtension
  • UnionTypeExtension
  • EnumTypeExtension
  • InputObjectTypeExtension

ScalarTypeDefinition : Description? scalar Name Directives[Const]?

ScalarTypeExtension :

  • extend scalar Name Directives[Const]

ObjectTypeDefinition : Description? type Name ImplementsInterfaces? Directives[Const]? FieldsDefinition?

ObjectTypeExtension :

  • extend type Name ImplementsInterfaces? Directives[Const]? FieldsDefinition
  • extend type Name ImplementsInterfaces? Directives[Const]
  • extend type Name ImplementsInterfaces

ImplementsInterfaces :

  • ImplementsInterfaces & NamedType
  • implements &? NamedType

FieldsDefinition : { FieldDefinition+ }

FieldDefinition : Description? Name ArgumentsDefinition? : Type Directives[Const]?

ArgumentsDefinition : ( InputValueDefinition+ )

InputValueDefinition : Description? Name : Type DefaultValue? Directives[Const]?

InterfaceTypeDefinition : Description? interface Name Directives[Const]? FieldsDefinition?

InterfaceTypeExtension :

  • extend interface Name Directives[Const]? FieldsDefinition
  • extend interface Name Directives[Const]

UnionTypeDefinition : Description? union Name Directives[Const]? UnionMemberTypes?

UnionMemberTypes :

  • UnionMemberTypes | NamedType
  • = |? NamedType

UnionTypeExtension :

  • extend union Name Directives[Const]? UnionMemberTypes
  • extend union Name Directives[Const]

EnumTypeDefinition : Description? enum Name Directives[Const]? EnumValuesDefinition?

EnumValuesDefinition : { EnumValueDefinition+ }

EnumValueDefinition : Description? EnumValue Directives[Const]?

EnumTypeExtension :

  • extend enum Name Directives[Const]? EnumValuesDefinition
  • extend enum Name Directives[Const]

InputObjectTypeDefinition : Description? input Name Directives[Const]? InputFieldsDefinition?

InputFieldsDefinition : { InputValueDefinition+ }

InputObjectTypeExtension :

  • extend input Name Directives[Const]? InputFieldsDefinition
  • extend input Name Directives[Const]

DirectiveDefinition : Description? directive @ Name ArgumentsDefinition? repeatable? on DirectiveLocations

DirectiveLocations :

  • DirectiveLocations | DirectiveLocation
  • |? DirectiveLocation

DirectiveLocation :

  • ExecutableDirectiveLocation
  • TypeSystemDirectiveLocation

ExecutableDirectiveLocation : one of QUERY MUTATION SUBSCRIPTION FIELD FRAGMENT_DEFINITION FRAGMENT_SPREAD INLINE_FRAGMENT VARIABLE_DEFINITION

TypeSystemDirectiveLocation : one of SCHEMA SCALAR OBJECT FIELD_DEFINITION ARGUMENT_DEFINITION INTERFACE UNION ENUM ENUM_VALUE INPUT_OBJECT INPUT_FIELD_DEFINITION