Summary of the Grammar

Summary of the Grammar

Lexical Structure

Grammar of whitespace

whitespace → whitespace-item whitespace opt

whitespace-item → line-break

whitespace-item → inline-space

whitespace-item → comment

whitespace-item → multiline-comment

whitespace-item → U+0000, U+000B, or U+000C

line-break → U+000A

line-break → U+000D

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

inline-spaces → inline-space inline-spaces opt

inline-space → U+0009 or U+0020

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 → identifier-head identifier-characters opt

identifier → ` identifier-head identifier-characters opt `

identifier → implicit-parameter-name

identifier → property-wrapper-projection

identifier-list → identifier | identifier , identifier-list

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

literal → numeric-literal | string-literal | boolean-literal | nil-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 → static-string-literal | interpolated-string-literal

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

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

static-string-literal → string-literal-opening-delimiter quoted-text opt string-literal-closing-delimiter

static-string-literal → multiline-string-literal-opening-delimiter multiline-quoted-text opt multiline-string-literal-closing-delimiter

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-string-literal → string-literal-opening-delimiter interpolated-text opt string-literal-closing-delimiter

interpolated-string-literal → multiline-string-literal-opening-delimiter multiline-interpolated-text opt multiline-string-literal-closing-delimiter

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 inline-spaces opt line-break

Grammar of operators

operator → operator-head operator-characters opt

operator → dot-operator-head dot-operator-characters

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

Types

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 → any-type

type → self-type

type → ( type )

Grammar of a type annotation

type-annotation → : attributes opt inoutopt type

Grammar of a type identifier

type-identifier → type-name generic-argument-clause opt | type-name generic-argument-clause opt . type-identifier

type-name → 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 an Any type

any-type → Any

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

Expressions

Grammar of an expression

expression → try-operator opt prefix-expression binary-expressions opt

expression-list → expression | expression , expression-list

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 | #fileID | #filePath

literal-expression → #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-expression → self | self-method-expression | self-subscript-expression | self-initializer-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-expression → superclass-method-expression | superclass-subscript-expression | superclass-initializer-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-expression → postfix-expression function-call-argument-clause

function-call-expression → postfix-expression function-call-argument-clause opt trailing-closures

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 ?

Statements

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

condition-list → condition | condition , condition-list

condition → expression | availability-condition | case-condition | optional-binding-condition

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

conditional-compilation-block → if-directive-clause elseif-directive-clauses opt else-directive-clause opt endif-directive

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 → macCatalyst | macCatalystApplicationExtension

platform-name → watchOS

platform-name → tvOS

platform-version → decimal-digits

platform-version → decimal-digits . decimal-digits

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

Declarations

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 → variable-declaration-head pattern-initializer-list

variable-declaration → variable-declaration-head variable-name type-annotation code-block

variable-declaration → variable-declaration-head variable-name type-annotation getter-setter-block

variable-declaration → variable-declaration-head variable-name type-annotation getter-setter-keyword-block

variable-declaration → variable-declaration-head variable-name initializer willSet-didSet-block

variable-declaration → variable-declaration-head variable-name type-annotation initializer opt willSet-didSet-block

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-declaration → function-head function-name generic-parameter-clause opt function-signature generic-where-clause opt function-body opt

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

enum-declaration → attributes opt access-level-modifier opt union-style-enum

enum-declaration → attributes opt access-level-modifier opt raw-value-style-enum

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-declaration → attributes opt access-level-modifier opt finalopt class class-name generic-parameter-clause opt type-inheritance-clause opt generic-where-clause opt class-body

class-declaration → attributes opt final access-level-modifier opt class class-name generic-parameter-clause opt type-inheritance-clause opt generic-where-clause opt class-body

class-name → identifier

class-body → { class-members opt }

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-members → protocol-member protocol-members opt

protocol-member → protocol-member-declaration | compiler-control-statement

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

protocol-property-declaration → variable-declaration-head variable-name type-annotation getter-setter-keyword-block

Grammar of a protocol method declaration

protocol-method-declaration → function-head function-name generic-parameter-clause opt function-signature generic-where-clause opt

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

protocol-subscript-declaration → subscript-head subscript-result generic-where-clause opt getter-setter-keyword-block

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

subscript-declaration → subscript-head subscript-result generic-where-clause opt code-block

subscript-declaration → subscript-head subscript-result generic-where-clause opt getter-setter-block

subscript-declaration → subscript-head subscript-result generic-where-clause opt getter-setter-keyword-block

subscript-head → attributes opt declaration-modifiers opt subscript generic-parameter-clause opt parameter-clause

subscript-result → -> attributes opt type

Grammar of an operator declaration

operator-declaration → prefix-operator-declaration | postfix-operator-declaration | infix-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

Attributes

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 }

Patterns

Grammar of a pattern

pattern → wildcard-pattern type-annotation opt

pattern → identifier-pattern type-annotation opt

pattern → value-binding-pattern

pattern → tuple-pattern type-annotation opt

pattern → enum-case-pattern

pattern → optional-pattern

pattern → type-casting-pattern

pattern → expression-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