Summary of the Grammar

Lexical Structure

Grammar of whitespace

whitespace whitespace-item whitespace opt

whitespace-item line-break

whitespace-item comment

whitespace-item multiline-comment

whitespace-item U+0000, U+0009, U+000B, U+000C, or U+0020

line-break U+000A

line-break U+000D

line-break U+000D followed by U+000A

comment // comment-text line-break

multiline-comment /* multiline-comment-text */

comment-text comment-text-item comment-text opt

comment-text-item Any Unicode scalar value except U+000A or U+000D

multiline-comment-text multiline-comment-text-item multiline-comment-text opt

multiline-comment-text-item multiline-comment

multiline-comment-text-item comment-text-item

multiline-comment-text-item Any Unicode scalar value except /* or */

Grammar of an identifier

identifier-head Upper- or lowercase letter A through Z

identifier-head _

identifier-head U+00A8, U+00AA, U+00AD, U+00AF, U+00B2–U+00B5, or U+00B7–U+00BA

identifier-head U+00BC–U+00BE, U+00C0–U+00D6, U+00D8–U+00F6, or U+00F8–U+00FF

identifier-head U+0100–U+02FF, U+0370–U+167F, U+1681–U+180D, or U+180F–U+1DBF

identifier-head U+1E00–U+1FFF

identifier-head U+200B–U+200D, U+202A–U+202E, U+203F–U+2040, U+2054, or U+2060–U+206F

identifier-head U+2070–U+20CF, U+2100–U+218F, U+2460–U+24FF, or U+2776–U+2793

identifier-head U+2C00–U+2DFF or U+2E80–U+2FFF

identifier-head U+3004–U+3007, U+3021–U+302F, U+3031–U+303F, or U+3040–U+D7FF

identifier-head U+F900–U+FD3D, U+FD40–U+FDCF, U+FDF0–U+FE1F, or U+FE30–U+FE44

identifier-head U+FE47–U+FFFD

identifier-head U+10000–U+1FFFD, U+20000–U+2FFFD, U+30000–U+3FFFD, or U+40000–U+4FFFD

identifier-head U+50000–U+5FFFD, U+60000–U+6FFFD, U+70000–U+7FFFD, or U+80000–U+8FFFD

identifier-head U+90000–U+9FFFD, U+A0000–U+AFFFD, U+B0000–U+BFFFD, or U+C0000–U+CFFFD

identifier-head U+D0000–U+DFFFD or U+E0000–U+EFFFD

identifier-character Digit 0 through 9

identifier-character U+0300–U+036F, U+1DC0–U+1DFF, U+20D0–U+20FF, or U+FE20–U+FE2F

identifier-character identifier-head

identifier-characters identifier-character identifier-characters opt

implicit-parameter-name $ decimal-digits

property-wrapper-projection $ identifier-characters

Grammar of a literal

numeric-literal -opt integer-literal | -opt floating-point-literal

boolean-literal true | false

nil-literal nil

Grammar of an integer literal

integer-literal binary-literal

integer-literal octal-literal

integer-literal decimal-literal

integer-literal hexadecimal-literal

binary-literal 0b binary-digit binary-literal-characters opt

binary-digit Digit 0 or 1

binary-literal-character binary-digit | _

binary-literal-characters binary-literal-character binary-literal-characters opt

octal-literal 0o octal-digit octal-literal-characters opt

octal-digit Digit 0 through 7

octal-literal-character octal-digit | _

octal-literal-characters octal-literal-character octal-literal-characters opt

decimal-literal decimal-digit decimal-literal-characters opt

decimal-digit Digit 0 through 9

decimal-digits decimal-digit decimal-digits opt

decimal-literal-character decimal-digit | _

decimal-literal-characters decimal-literal-character decimal-literal-characters opt

hexadecimal-literal 0x hexadecimal-digit hexadecimal-literal-characters opt

hexadecimal-digit Digit 0 through 9, a through f, or A through F

hexadecimal-literal-character hexadecimal-digit | _

hexadecimal-literal-characters hexadecimal-literal-character hexadecimal-literal-characters opt

Grammar of a floating-point literal

floating-point-literal decimal-literal decimal-fraction opt decimal-exponent opt

floating-point-literal hexadecimal-literal hexadecimal-fraction opt hexadecimal-exponent

decimal-fraction . decimal-literal

decimal-exponent floating-point-e sign opt decimal-literal

hexadecimal-fraction . hexadecimal-digit hexadecimal-literal-characters opt

hexadecimal-exponent floating-point-p sign opt decimal-literal

floating-point-e e | E

floating-point-p p | P

sign + | -

Grammar of a string literal

string-literal-opening-delimiter extended-string-literal-delimiter opt "

string-literal-closing-delimiter " extended-string-literal-delimiter opt

multiline-string-literal-opening-delimiter extended-string-literal-delimiter """

multiline-string-literal-closing-delimiter """ extended-string-literal-delimiter

extended-string-literal-delimiter # extended-string-literal-delimiter opt

quoted-text quoted-text-item quoted-text opt

quoted-text-item escaped-character

quoted-text-item Any Unicode scalar value except ", \, U+000A, or U+000D

multiline-quoted-text multiline-quoted-text-item multiline-quoted-text opt

multiline-quoted-text-item escaped-character

multiline-quoted-text-item Any Unicode scalar value except \

multiline-quoted-text-item escaped-newline

interpolated-text interpolated-text-item interpolated-text opt

interpolated-text-item \( expression ) | quoted-text-item

multiline-interpolated-text multiline-interpolated-text-item multiline-interpolated-text opt

multiline-interpolated-text-item \( expression ) | multiline-quoted-text-item

escape-sequence \ extended-string-literal-delimiter

escaped-character escape-sequence 0 | escape-sequence \ | escape-sequence t | escape-sequence n | escape-sequence r | escape-sequence " | escape-sequence '

escaped-character escape-sequence u { unicode-scalar-digits }

unicode-scalar-digits Between one and eight hexadecimal digits

escaped-newline escape-sequence whitespace opt line-break

Grammar of operators

operator-head / | = | - | + | ! | * | % | < | > | & | | | ^ | ~ | ?

operator-head U+00A1–U+00A7

operator-head U+00A9 or U+00AB

operator-head U+00AC or U+00AE

operator-head U+00B0–U+00B1

operator-head U+00B6, U+00BB, U+00BF, U+00D7, or U+00F7

operator-head U+2016–U+2017

operator-head U+2020–U+2027

operator-head U+2030–U+203E

operator-head U+2041–U+2053

operator-head U+2055–U+205E

operator-head U+2190–U+23FF

operator-head U+2500–U+2775

operator-head U+2794–U+2BFF

operator-head U+2E00–U+2E7F

operator-head U+3001–U+3003

operator-head U+3008–U+3020

operator-head U+3030

operator-character operator-head

operator-character U+0300–U+036F

operator-character U+1DC0–U+1DFF

operator-character U+20D0–U+20FF

operator-character U+FE00–U+FE0F

operator-character U+FE20–U+FE2F

operator-character U+E0100–U+E01EF

operator-characters operator-character operator-characters opt

dot-operator-head .

dot-operator-character . | operator-character

dot-operator-characters dot-operator-character dot-operator-characters opt

binary-operator operator

prefix-operator operator

postfix-operator operator


Grammar of a type

type function-type

type array-type

type dictionary-type

type type-identifier

type tuple-type

type optional-type

type implicitly-unwrapped-optional-type

type protocol-composition-type

type opaque-type

type metatype-type

type self-type

type Any

type ( type )

Grammar of a type annotation

type-annotation : attributes opt inoutopt type

Grammar of a type identifier

Grammar of a tuple type

tuple-type ( ) | ( tuple-type-element , tuple-type-element-list )

tuple-type-element-list tuple-type-element | tuple-type-element , tuple-type-element-list

tuple-type-element element-name type-annotation | type

element-name identifier

Grammar of a function type

function-type attributes opt function-type-argument-clause throwsopt -> type

function-type-argument-clause ( )

function-type-argument-clause ( function-type-argument-list ...opt )

function-type-argument-list function-type-argument | function-type-argument , function-type-argument-list

function-type-argument attributes opt inoutopt type | argument-label type-annotation

argument-label identifier

Grammar of an array type

array-type [ type ]

Grammar of a dictionary type

dictionary-type [ type : type ]

Grammar of an optional type

optional-type type ?

Grammar of an implicitly unwrapped optional type

implicitly-unwrapped-optional-type type !

Grammar of a protocol composition type

protocol-composition-type type-identifier & protocol-composition-continuation

protocol-composition-continuation type-identifier | protocol-composition-type

Grammar of an opaque type

opaque-type some type

Grammar of a metatype type

metatype-type type . Type | type . Protocol

Grammar of a Self type

self-type Self

Grammar of a type inheritance clause

type-inheritance-clause : type-inheritance-list

type-inheritance-list type-identifier | type-identifier , type-inheritance-list


Grammar of an expression

Grammar of a prefix expression

prefix-expression prefix-operator opt postfix-expression

prefix-expression in-out-expression

in-out-expression & identifier

Grammar of a try expression

try-operator try | try ? | try !

Grammar of a binary expression

binary-expression binary-operator prefix-expression

binary-expression assignment-operator try-operator opt prefix-expression

binary-expression conditional-operator try-operator opt prefix-expression

binary-expression type-casting-operator

binary-expressions binary-expression binary-expressions opt

Grammar of an assignment operator

assignment-operator =

Grammar of a conditional operator

conditional-operator ? expression :

Grammar of a type-casting operator

type-casting-operator is type

type-casting-operator as type

type-casting-operator as ? type

type-casting-operator as ! type

Grammar of a primary expression

primary-expression identifier generic-argument-clause opt

primary-expression literal-expression

primary-expression self-expression

primary-expression superclass-expression

primary-expression closure-expression

primary-expression parenthesized-expression

primary-expression tuple-expression

primary-expression implicit-member-expression

primary-expression wildcard-expression

primary-expression key-path-expression

primary-expression selector-expression

primary-expression key-path-string-expression

Grammar of a literal expression

literal-expression literal

literal-expression array-literal | dictionary-literal | playground-literal

literal-expression #file | #filePath | #line | #column | #function | #dsohandle

array-literal [ array-literal-items opt ]

array-literal-items array-literal-item ,opt | array-literal-item , array-literal-items

array-literal-item expression

dictionary-literal [ dictionary-literal-items ] | [ : ]

dictionary-literal-items dictionary-literal-item ,opt | dictionary-literal-item , dictionary-literal-items

dictionary-literal-item expression : expression

playground-literal #colorLiteral ( red : expression , green : expression , blue : expression , alpha : expression )

playground-literal #fileLiteral ( resourceName : expression )

playground-literal #imageLiteral ( resourceName : expression )

Grammar of a self expression

self-method-expression self . identifier

self-subscript-expression self [ function-call-argument-list ]

self-initializer-expression self . init

Grammar of a superclass expression

superclass-method-expression super . identifier

superclass-subscript-expression super [ function-call-argument-list ]

superclass-initializer-expression super . init

Grammar of a closure expression

closure-expression { closure-signature opt statements opt }

closure-signature capture-list opt closure-parameter-clause throwsopt function-result opt in

closure-signature capture-list in

closure-parameter-clause ( ) | ( closure-parameter-list ) | identifier-list

closure-parameter-list closure-parameter | closure-parameter , closure-parameter-list

closure-parameter closure-parameter-name type-annotation opt

closure-parameter closure-parameter-name type-annotation ...

closure-parameter-name identifier

capture-list [ capture-list-items ]

capture-list-items capture-list-item | capture-list-item , capture-list-items

capture-list-item capture-specifier opt expression

capture-specifier weak | unowned | unowned(safe) | unowned(unsafe)

Grammar of a implicit member expression

implicit-member-expression . identifier

Grammar of a parenthesized expression

parenthesized-expression ( expression )

Grammar of a tuple expression

tuple-expression ( ) | ( tuple-element , tuple-element-list )

tuple-element-list tuple-element | tuple-element , tuple-element-list

tuple-element expression | identifier : expression

Grammar of a wildcard expression

wildcard-expression _

Grammar of a key-path expression

key-path-expression \ type opt . key-path-components

key-path-components key-path-component | key-path-component . key-path-components

key-path-component identifier key-path-postfixes opt | key-path-postfixes

key-path-postfixes key-path-postfix key-path-postfixes opt

key-path-postfix ? | ! | self | [ function-call-argument-list ]

Grammar of a selector expression

selector-expression #selector ( expression )

selector-expression #selector ( getter: expression )

selector-expression #selector ( setter: expression )

Grammar of a key-path string expression

key-path-string-expression #keyPath ( expression )

Grammar of a postfix expression

postfix-expression primary-expression

postfix-expression postfix-expression postfix-operator

postfix-expression function-call-expression

postfix-expression initializer-expression

postfix-expression explicit-member-expression

postfix-expression postfix-self-expression

postfix-expression subscript-expression

postfix-expression forced-value-expression

postfix-expression optional-chaining-expression

Grammar of a function call expression

function-call-argument-clause ( ) | ( function-call-argument-list )

function-call-argument-list function-call-argument | function-call-argument , function-call-argument-list

function-call-argument expression | identifier : expression

function-call-argument operator | identifier : operator

trailing-closures closure-expression labeled-trailing-closures opt

labeled-trailing-closures labeled-trailing-closure labeled-trailing-closures opt

labeled-trailing-closure identifier : closure-expression

Grammar of an initializer expression

initializer-expression postfix-expression . init

initializer-expression postfix-expression . init ( argument-names )

Grammar of an explicit member expression

explicit-member-expression postfix-expression . decimal-digits

explicit-member-expression postfix-expression . identifier generic-argument-clause opt

explicit-member-expression postfix-expression . identifier ( argument-names )

argument-names argument-name argument-names opt

argument-name identifier :

Grammar of a postfix self expression

postfix-self-expression postfix-expression . self

Grammar of a subscript expression

subscript-expression postfix-expression [ function-call-argument-list ]

Grammar of a forced-value expression

forced-value-expression postfix-expression !

Grammar of an optional-chaining expression

optional-chaining-expression postfix-expression ?


Grammar of a statement

statement expression ;opt

statement declaration ;opt

statement loop-statement ;opt

statement branch-statement ;opt

statement labeled-statement ;opt

statement control-transfer-statement ;opt

statement defer-statement ;opt

statement do-statement ;opt

statement compiler-control-statement

statements statement statements opt

Grammar of a loop statement

loop-statement for-in-statement

loop-statement while-statement

loop-statement repeat-while-statement

Grammar of a for-in statement

for-in-statement for caseopt pattern in expression where-clause opt code-block

Grammar of a while statement

while-statement while condition-list code-block

case-condition case pattern initializer

optional-binding-condition let pattern initializer | var pattern initializer

Grammar of a repeat-while statement

repeat-while-statement repeat code-block while expression

Grammar of a branch statement

branch-statement if-statement

branch-statement guard-statement

branch-statement switch-statement

Grammar of an if statement

if-statement if condition-list code-block else-clause opt

else-clause else code-block | else if-statement

Grammar of a guard statement

guard-statement guard condition-list else code-block

Grammar of a switch statement

switch-statement switch expression { switch-cases opt }

switch-cases switch-case switch-cases opt

switch-case case-label statements

switch-case default-label statements

switch-case conditional-switch-case

case-label attributes opt case case-item-list :

case-item-list pattern where-clause opt | pattern where-clause opt , case-item-list

default-label attributes opt default :

where-clause where where-expression

where-expression expression

conditional-switch-case switch-if-directive-clause switch-elseif-directive-clauses opt switch-else-directive-clause opt endif-directive

switch-if-directive-clause if-directive compilation-condition switch-cases opt

switch-elseif-directive-clauses elseif-directive-clause switch-elseif-directive-clauses opt

switch-elseif-directive-clause elseif-directive compilation-condition switch-cases opt

switch-else-directive-clause else-directive switch-cases opt

Grammar of a labeled statement

labeled-statement statement-label loop-statement

labeled-statement statement-label if-statement

labeled-statement statement-label switch-statement

labeled-statement statement-label do-statement

statement-label label-name :

label-name identifier

Grammar of a control transfer statement

control-transfer-statement break-statement

control-transfer-statement continue-statement

control-transfer-statement fallthrough-statement

control-transfer-statement return-statement

control-transfer-statement throw-statement

Grammar of a break statement

break-statement break label-name opt

Grammar of a continue statement

continue-statement continue label-name opt

Grammar of a fallthrough statement

fallthrough-statement fallthrough

Grammar of a return statement

return-statement return expression opt

Grammar of a throw statement

throw-statement throw expression

Grammar of a defer statement

defer-statement defer code-block

Grammar of a do statement

do-statement do code-block catch-clauses opt

catch-clauses catch-clause catch-clauses opt

catch-clause catch catch-pattern-list opt code-block

catch-pattern-list catch-pattern | catch-pattern , catch-pattern-list

catch-pattern pattern where-clause opt

Grammar of a compiler control statement

compiler-control-statement conditional-compilation-block

compiler-control-statement line-control-statement

compiler-control-statement diagnostic-statement

Grammar of a conditional compilation block

if-directive-clause if-directive compilation-condition statements opt

elseif-directive-clauses elseif-directive-clause elseif-directive-clauses opt

elseif-directive-clause elseif-directive compilation-condition statements opt

else-directive-clause else-directive statements opt

if-directive #if

elseif-directive #elseif

else-directive #else

endif-directive #endif

compilation-condition platform-condition

compilation-condition identifier

compilation-condition boolean-literal

compilation-condition ( compilation-condition )

compilation-condition ! compilation-condition

compilation-condition compilation-condition && compilation-condition

compilation-condition compilation-condition || compilation-condition

platform-condition os ( operating-system )

platform-condition arch ( architecture )

platform-condition swift ( >= swift-version ) | swift ( < swift-version )

platform-condition compiler ( >= swift-version ) | compiler ( < swift-version )

platform-condition canImport ( module-name )

platform-condition targetEnvironment ( environment )

operating-system macOS | iOS | watchOS | tvOS

architecture i386 | x86_64 | arm | arm64

swift-version decimal-digits swift-version-continuation opt

swift-version-continuation . decimal-digits swift-version-continuation opt

module-name identifier

environment simulator | macCatalyst

Grammar of a line control statement

line-control-statement #sourceLocation ( file: file-path , line: line-number )

line-control-statement #sourceLocation ( )

line-number A decimal integer greater than zero

file-path static-string-literal

Grammar of a compile-time diagnostic statement

diagnostic-statement #error ( diagnostic-message )

diagnostic-statement #warning ( diagnostic-message )

diagnostic-message static-string-literal

Grammar of an availability condition

availability-condition #available ( availability-arguments )

availability-arguments availability-argument | availability-argument , availability-arguments

availability-argument platform-name platform-version

availability-argument *

platform-name iOS | iOSApplicationExtension

platform-name macOS | macOSApplicationExtension

platform-name watchOS

platform-name tvOS

platform-version decimal-digits

platform-version decimal-digits . decimal-digits

platform-version decimal-digits . decimal-digits . decimal-digits


Grammar of a declaration

declaration import-declaration

declaration constant-declaration

declaration variable-declaration

declaration typealias-declaration

declaration function-declaration

declaration enum-declaration

declaration struct-declaration

declaration class-declaration

declaration protocol-declaration

declaration initializer-declaration

declaration deinitializer-declaration

declaration extension-declaration

declaration subscript-declaration

declaration operator-declaration

declaration precedence-group-declaration

declarations declaration declarations opt

Grammar of a top-level declaration

top-level-declaration statements opt

Grammar of a code block

code-block { statements opt }

Grammar of an import declaration

import-declaration attributes opt import import-kind opt import-path

import-kind typealias | struct | class | enum | protocol | let | var | func

import-path import-path-identifier | import-path-identifier . import-path

import-path-identifier identifier | operator

Grammar of a constant declaration

constant-declaration attributes opt declaration-modifiers opt let pattern-initializer-list

pattern-initializer-list pattern-initializer | pattern-initializer , pattern-initializer-list

pattern-initializer pattern initializer opt

initializer = expression

Grammar of a variable declaration

variable-declaration-head attributes opt declaration-modifiers opt var

variable-name identifier

getter-setter-block code-block

getter-setter-block { getter-clause setter-clause opt }

getter-setter-block { setter-clause getter-clause }

getter-clause attributes opt mutation-modifier opt get code-block

setter-clause attributes opt mutation-modifier opt set setter-name opt code-block

setter-name ( identifier )

getter-setter-keyword-block { getter-keyword-clause setter-keyword-clause opt }

getter-setter-keyword-block { setter-keyword-clause getter-keyword-clause }

getter-keyword-clause attributes opt mutation-modifier opt get

setter-keyword-clause attributes opt mutation-modifier opt set

willSet-didSet-block { willSet-clause didSet-clause opt }

willSet-didSet-block { didSet-clause willSet-clause opt }

willSet-clause attributes opt willSet setter-name opt code-block

didSet-clause attributes opt didSet setter-name opt code-block

Grammar of a type alias declaration

typealias-declaration attributes opt access-level-modifier opt typealias typealias-name generic-parameter-clause opt typealias-assignment

typealias-name identifier

typealias-assignment = type

Grammar of a function declaration

function-head attributes opt declaration-modifiers opt func

function-name identifier | operator

function-signature parameter-clause throwsopt function-result opt

function-signature parameter-clause rethrows function-result opt

function-result -> attributes opt type

function-body code-block

parameter-clause ( ) | ( parameter-list )

parameter-list parameter | parameter , parameter-list

parameter external-parameter-name opt local-parameter-name type-annotation default-argument-clause opt

parameter external-parameter-name opt local-parameter-name type-annotation

parameter external-parameter-name opt local-parameter-name type-annotation ...

external-parameter-name identifier

local-parameter-name identifier

default-argument-clause = expression

Grammar of an enumeration declaration

union-style-enum indirectopt enum enum-name generic-parameter-clause opt type-inheritance-clause opt generic-where-clause opt { union-style-enum-members opt }

union-style-enum-members union-style-enum-member union-style-enum-members opt

union-style-enum-member declaration | union-style-enum-case-clause | compiler-control-statement

union-style-enum-case-clause attributes opt indirectopt case union-style-enum-case-list

union-style-enum-case-list union-style-enum-case | union-style-enum-case , union-style-enum-case-list

union-style-enum-case enum-case-name tuple-type opt

enum-name identifier

enum-case-name identifier

raw-value-style-enum enum enum-name generic-parameter-clause opt type-inheritance-clause generic-where-clause opt { raw-value-style-enum-members }

raw-value-style-enum-members raw-value-style-enum-member raw-value-style-enum-members opt

raw-value-style-enum-member declaration | raw-value-style-enum-case-clause | compiler-control-statement

raw-value-style-enum-case-clause attributes opt case raw-value-style-enum-case-list

raw-value-style-enum-case-list raw-value-style-enum-case | raw-value-style-enum-case , raw-value-style-enum-case-list

raw-value-style-enum-case enum-case-name raw-value-assignment opt

raw-value-assignment = raw-value-literal

raw-value-literal numeric-literal | static-string-literal | boolean-literal

Grammar of a structure declaration

struct-declaration attributes opt access-level-modifier opt struct struct-name generic-parameter-clause opt type-inheritance-clause opt generic-where-clause opt struct-body

struct-name identifier

struct-body { struct-members opt }

struct-members struct-member struct-members opt

struct-member declaration | compiler-control-statement

Grammar of a class declaration

class-members class-member class-members opt

class-member declaration | compiler-control-statement

Grammar of a protocol declaration

protocol-declaration attributes opt access-level-modifier opt protocol protocol-name type-inheritance-clause opt generic-where-clause opt protocol-body

protocol-name identifier

protocol-body { protocol-members opt }

protocol-member-declaration protocol-property-declaration

protocol-member-declaration protocol-method-declaration

protocol-member-declaration protocol-initializer-declaration

protocol-member-declaration protocol-subscript-declaration

protocol-member-declaration protocol-associated-type-declaration

protocol-member-declaration typealias-declaration

Grammar of a protocol property declaration

Grammar of a protocol method declaration

Grammar of a protocol initializer declaration

protocol-initializer-declaration initializer-head generic-parameter-clause opt parameter-clause throwsopt generic-where-clause opt

protocol-initializer-declaration initializer-head generic-parameter-clause opt parameter-clause rethrows generic-where-clause opt

Grammar of a protocol subscript declaration

Grammar of a protocol associated type declaration

protocol-associated-type-declaration attributes opt access-level-modifier opt associatedtype typealias-name type-inheritance-clause opt typealias-assignment opt generic-where-clause opt

Grammar of an initializer declaration

initializer-declaration initializer-head generic-parameter-clause opt parameter-clause throwsopt generic-where-clause opt initializer-body

initializer-declaration initializer-head generic-parameter-clause opt parameter-clause rethrows generic-where-clause opt initializer-body

initializer-head attributes opt declaration-modifiers opt init

initializer-head attributes opt declaration-modifiers opt init ?

initializer-head attributes opt declaration-modifiers opt init !

initializer-body code-block

Grammar of a deinitializer declaration

deinitializer-declaration attributes opt deinit code-block

Grammar of an extension declaration

extension-declaration attributes opt access-level-modifier opt extension type-identifier type-inheritance-clause opt generic-where-clause opt extension-body

extension-body { extension-members opt }

extension-members extension-member extension-members opt

extension-member declaration | compiler-control-statement

Grammar of a subscript declaration

Grammar of an operator declaration

prefix-operator-declaration prefix operator operator

postfix-operator-declaration postfix operator operator

infix-operator-declaration infix operator operator infix-operator-group opt

infix-operator-group : precedence-group-name

Grammar of a precedence group declaration

precedence-group-declaration precedencegroup precedence-group-name { precedence-group-attributes opt }

precedence-group-attributes precedence-group-attribute precedence-group-attributes opt

precedence-group-attribute precedence-group-relation

precedence-group-attribute precedence-group-assignment

precedence-group-attribute precedence-group-associativity

precedence-group-relation higherThan : precedence-group-names

precedence-group-relation lowerThan : precedence-group-names

precedence-group-assignment assignment : boolean-literal

precedence-group-associativity associativity : left

precedence-group-associativity associativity : right

precedence-group-associativity associativity : none

precedence-group-names precedence-group-name | precedence-group-name , precedence-group-names

precedence-group-name identifier

Grammar of a declaration modifier

declaration-modifier class | convenience | dynamic | final | infix | lazy | optional | override | postfix | prefix | required | static | unowned | unowned ( safe ) | unowned ( unsafe ) | weak

declaration-modifier access-level-modifier

declaration-modifier mutation-modifier

declaration-modifiers declaration-modifier declaration-modifiers opt

access-level-modifier private | private ( set )

access-level-modifier fileprivate | fileprivate ( set )

access-level-modifier internal | internal ( set )

access-level-modifier public | public ( set )

access-level-modifier open | open ( set )

mutation-modifier mutating | nonmutating


Grammar of an attribute

attribute @ attribute-name attribute-argument-clause opt

attribute-name identifier

attribute-argument-clause ( balanced-tokens opt )

attributes attribute attributes opt

balanced-tokens balanced-token balanced-tokens opt

balanced-token ( balanced-tokens opt )

balanced-token [ balanced-tokens opt ]

balanced-token { balanced-tokens opt }

balanced-token Any identifier, keyword, literal, or operator

balanced-token Any punctuation except (, ), [, ], {, or }


Grammar of a pattern

Grammar of a wildcard pattern

wildcard-pattern _

Grammar of an identifier pattern

identifier-pattern identifier

Grammar of a value-binding pattern

value-binding-pattern var pattern | let pattern

Grammar of a tuple pattern

tuple-pattern ( tuple-pattern-element-list opt )

tuple-pattern-element-list tuple-pattern-element | tuple-pattern-element , tuple-pattern-element-list

tuple-pattern-element pattern | identifier : pattern

Grammar of an enumeration case pattern

enum-case-pattern type-identifier opt . enum-case-name tuple-pattern opt

Grammar of an optional pattern

optional-pattern identifier-pattern ?

Grammar of a type casting pattern

type-casting-pattern is-pattern | as-pattern

is-pattern is type

as-pattern pattern as type

Grammar of an expression pattern

expression-pattern expression

Generic Parameters and Arguments

Grammar of a generic parameter clause

generic-parameter-clause < generic-parameter-list >

generic-parameter-list generic-parameter | generic-parameter , generic-parameter-list

generic-parameter type-name

generic-parameter type-name : type-identifier

generic-parameter type-name : protocol-composition-type

generic-where-clause where requirement-list

requirement-list requirement | requirement , requirement-list

requirement conformance-requirement | same-type-requirement

conformance-requirement type-identifier : type-identifier

conformance-requirement type-identifier : protocol-composition-type

same-type-requirement type-identifier == type

Grammar of a generic argument clause

generic-argument-clause < generic-argument-list >

generic-argument-list generic-argument | generic-argument , generic-argument-list

generic-argument type

Generic Parameters and Arguments

Revision History

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

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