Swift 语法总结


本页包含内容:

语句

语句语法
statementexpression ; opt
statementdeclaration ; opt
statementloop-statement ; opt
statementbranch-statement ; opt
statementlabeled-statement
statementcontrol-transfer-statement ; opt
statementsstatement statements opt

循环语句语法
loop-statementfor-statement
loop-statementfor-in-statement
loop-statementwhile-statement
loop-statementdo-while-statement

For 循环语法
for-statementfor for-init opt ; expression opt ; expression opt code-block
for-statementfor ( for-init opt ; expression opt ; expression opt ) code-block
for-initvariable-declaration | expression-list

For-In 循环语法
for-in-statementfor pattern in expression code-block

While 循环语法
while-statementwhile while-condition code-block
while-conditionexpression | declaration

Do-While 循环语法
do-while-statementdo code-block while while-condition

分支语句语法
branch-statementif-statement
branch-statementswitch-statement

If 语句语法
if-statementif if-condition code-block else-clause opt
if-conditionexpression | declaration
else-clauseelse code-block | else if-statement

Switch 语句语法
switch-statementswitch expression { switch-cases opt }
switch-casesswitch-case switch-cases opt
switch-casecase-label statements | default-label statements
switch-casecase-label ; | default-label ;
case-labelcase case-item-list :
case-item-listpattern guard-clause opt | pattern guard-clause opt , case-item-list
default-labeldefault :
guard-clausewhere guard-expression
guard-expressionexpression

带标签的语句语法
labeled-statementstatement-label loop-statement | statement-label switch-statement
statement-labellabel-name :
label-nameidentifier

控制传递语句语法
control-transfer-statementbreak-statement
control-transfer-statementcontinue-statement
control-transfer-statementfallthrough-statement
control-transfer-statementreturn-statement

Break 语句语法
break-statementbreak label-name opt

Continue 语句语法
continue-statementcontinue label-name opt

Fallthrough 语句语法
fallthrough-statementfallthrough

Return 语句语法
return-statementreturn expression opt

泛型参数

泛型形参子句语法
generic-parameter-clause< generic-parameter-list requirement-clause opt >
generic-parameter-listgeneric-parameter | generic-parameter , generic-parameter-list
generic-parametertype-name
generic-parametertype-name : type-identifier
generic-parametertype-name : protocol-composition-type
requirement-clausewhere requirement-list
requirement-listrequirement | requirement , requirement-list
requirementconformance-requirement | same-type-requirement
conformance-requirementtype-identifier : type-identifier
conformance-requirementtype-identifier : protocol-composition-type
same-type-requirementtype-identifier == type-identifier

泛型实参子句语法
generic-argument-clause< generic-argument-list >
generic-argument-listgeneric-argument | generic-argument , generic-argument-list
generic-argumenttype

声明 (Declarations)

声明语法
declarationimport-declaration
declarationconstant-declaration
declarationvariable-declaration
declarationtypealias-declaration
declarationfunction-declaration
declarationenum-declaration
declarationstruct-declaration
declarationclass-declaration
declarationprotocol-declaration
declarationinitializer-declaration
declarationdeinitializer-declaration
declarationextension-declaration
declarationsubscript-declaration
declarationoperator-declaration
declarationsdeclaration declarations opt
declaration-specifiersdeclaration-specifier declaration-specifiers opt
declaration-specifierclass | mutating | nonmutating | override | static | unowned | unowned(safe) | unowned(unsafe) | weak

顶级声明语法
top-level-declarationstatements opt

代码块语法
code-block{ statements opt }

Import 声明语法
import-declarationattributes opt import import-kind opt import-path
import-kindtypealias | struct | class | enum | protocol | var | func
import-pathimport-path-identifier | import-path-identifier . import-path
import-path-identifieridentifier | operator

常数声明语法
constant-declarationattributes opt declaration-specifiers opt let pattern-initializer-list
pattern-initializer-listpattern-initializer | pattern-initializer , pattern-initializer-list
pattern-initializerpattern initializer opt
initializer= expression

变量声明语法
variable-declarationvariable-declaration-head pattern-initializer-list
variable-declarationvariable-declaration-head variable-name type-annotation code-block
variable-declarationvariable-declaration-head variable-name type-annotation getter-setter-block
variable-declarationvariable-declaration-head variable-name type-annotation getter-setter-keyword-block
variable-declarationvariable-declaration-head variable-name type-annotation initializer opt willSet-didSet-block
variable-declaration-headattributes opt declaration-specifiers opt var
variable-nameidentifier
getter-setter-block{ getter-clause setter-clause opt }
getter-setter-block{ setter-clause getter-clause }
getter-clauseattributes opt get code-block
setter-clauseattributes 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-clauseattributes opt get
setter-keyword-clauseattributes opt set
willSet-didSet-block{ willSet-clause didSet-clause opt }
willSet-didSet-block{ didSet-clause willSet-clause }
willSet-clauseattributes opt willSet setter-name opt code-block
didSet-clauseattributes opt didSet setter-name opt code-block

类型别名声明语法
typealias-declarationtypealias-head typealias-assignment
typealias-headtypealias typealias-name
typealias-nameidentifier
typealias-assignment= type

函数声明语法
function-declarationfunction-head function-name generic-parameter-clause opt function-signature function-body
function-headattributes opt declaration-specifiers opt func
function-nameidentifier | operator
function-signatureparameter-clauses function-result opt
function-result-> attributes opt type
function-bodycode-block
parameter-clausesparameter-clause parameter-clauses opt
parameter-clause( ) | ( parameter-list ... opt )
parameter-listparameter | parameter , parameter-list
parameterinout opt let opt # opt parameter-name local-parameter-name opt type-annotation default-argument-clause opt
parameterinout opt var # opt parameter-name local-parameter-name opt type-annotation default-argument-clause opt
parameterattributes opt type
parameter-nameidentifier | _
local-parameter-nameidentifier | _
default-argument-clause= expression

枚举声明语法
enum-declarationattributes opt union-style-enum | attributes opt raw-value-style-enum
union-style-enumenum-name generic-parameter-clause opt { union-style-enum-members opt }
union-style-enum-membersunion-style-enum-member union-style-enum-members opt
union-style-enum-memberdeclaration | union-style-enum-case-clause
union-style-enum-case-clauseattributes opt case union-style-enum-case-list
union-style-enum-case-listunion-style-enum-case | union-style-enum-case , union-style-enum-case-list
union-style-enum-caseenum-case-name tuple-type opt
enum-nameidentifier
enum-case-nameidentifier
raw-value-style-enumenum-name generic-parameter-clause opt : type-identifier { raw-value-style-enum-members opt }
raw-value-style-enum-membersraw-value-style-enum-member raw-value-style-enum-members opt
raw-value-style-enum-memberdeclaration | raw-value-style-enum-case-clause
raw-value-style-enum-case-clauseattributes opt case raw-value-style-enum-case-list
raw-value-style-enum-case-listraw-value-style-enum-case | raw-value-style-enum-case , raw-value-style-enum-case-list
raw-value-style-enum-caseenum-case-name raw-value-assignment opt
raw-value-assignment= literal

结构体声明语法
struct-declarationattributes opt struct struct-name generic-parameter-clause opt type-inheritance-clause opt struct-body
struct-nameidentifier
struct-body{ declarations opt }

类声明语法
class-declarationattributes opt class class-name generic-parameter-clause opt type-inheritance-clause opt class-body
class-nameidentifier
class-body{ declarations opt }

协议声明语法
protocol-declarationattributes opt protocol protocol-name type-inheritance-clause opt protocol-body
protocol-nameidentifier
protocol-body{ protocol-member-declarations opt }
protocol-member-declarationprotocol-property-declaration
protocol-member-declarationprotocol-method-declaration
protocol-member-declarationprotocol-initializer-declaration
protocol-member-declarationprotocol-subscript-declaration
protocol-member-declarationprotocol-associated-type-declaration
protocol-member-declarationsprotocol-member-declaration protocol-member-declarations opt

协议属性声明语法
protocol-property-declarationvariable-declaration-head variable-name type-annotation getter-setter-keyword-block

协议方法声明语法
protocol-method-declarationfunction-head function-name generic-parameter-clause opt function-signature

协议构造函数声明语法
protocol-initializer-declarationinitializer-head generic-parameter-clause opt parameter-clause

协议附属脚本声明语法
protocol-subscript-declarationsubscript-head subscript-result getter-setter-keyword-block

协议关联类型声明语法
protocol-associated-type-declarationtypealias-head type-inheritance-clause opt typealias-assignment opt

构造函数声明语法
initializer-declarationinitializer-head generic-parameter-clause opt parameter-clause initializer-body
initializer-headattributes opt convenience opt init
initializer-bodycode-block

析构函数声明语法
deinitializer-declarationattributes opt deinit code-block

扩展声明语法
extension-declarationextension type-identifier type-inheritance-clause opt extension-body
extension-body{ declarations opt }

附属脚本声明语法
subscript-declarationsubscript-head subscript-result code-block
subscript-declarationsubscript-head subscript-result getter-setter-block
subscript-declarationsubscript-head subscript-result getter-setter-keyword-block
subscript-headattributes opt subscript parameter-clause
subscript-result-> attributes opt type

运算符声明语法
operator-declarationprefix-operator-declaration | postfix-operator-declaration | infix-operator-declaration
prefix-operator-declarationoperator prefix operator { }
postfix-operator-declarationoperator postfix operator { }
infix-operator-declarationoperator infix operator { infix-operator-attributes opt }
infix-operator-attributesprecedence-clause opt associativity-clause opt
precedence-clauseprecedence precedence-level
precedence-level → Digit 0 through 255
associativity-clauseassociativity associativity
associativityleft | right | none

模式

模式语法
patternwildcard-pattern type-annotation opt
patternidentifier-pattern type-annotation opt
patternvalue-binding-pattern
patterntuple-pattern type-annotation opt
patternenum-case-pattern
patterntype-casting-pattern
patternexpression-pattern

通配符模式语法
wildcard-pattern_

标识符模式语法
identifier-patternidentifier

值绑定模式语法
value-binding-patternvar pattern | let pattern

元组模式语法
tuple-pattern( tuple-pattern-element-list opt )
tuple-pattern-element-listtuple-pattern-element | tuple-pattern-element , tuple-pattern-element-list
tuple-pattern-elementpattern

枚举用例模式语法
enum-case-patterntype-identifier opt . enum-case-name tuple-pattern opt

类型转换模式语法
type-casting-patternis-pattern | as-pattern
is-patternis type
as-patternpattern as type

表达式模式语法
expression-patternexpression

特性

特性语法
attribute@ attribute-name attribute-argument-clause opt
attribute-nameidentifier
attribute-argument-clause( balanced-tokens opt )
attributesattribute attributes opt
balanced-tokensbalanced-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 }­

表达式

表达式语法
expressionprefix-expression binary-expressions opt
expression-listexpression | expression , expression-list

前缀表达式语法
prefix-expressionprefix-operator opt postfix-expression
prefix-expressionin-out-expression
in-out-expression& identifier

二进制表达式语法
binary-expressionbinary-operator prefix-expression
binary-expressionassignment-operator prefix-expression
binary-expressionconditional-operator prefix-expression
binary-expressiontype-casting-operator
binary-expressionsbinary-expression binary-expressions opt

赋值运算符语法
assignment-operator=

条件运算符语法
conditional-operator? expression :

类型转换运算符语法
type-casting-operatoris type | as ? opt type

主表达式语法
primary-expressionidentifier generic-argument-clause opt
primary-expressionliteral-expression
primary-expressionself-expression
primary-expressionsuperclass-expression
primary-expressionclosure-expression
primary-expressionparenthesized-expression
primary-expressionimplicit-member-expression
primary-expressionwildcard-expression

字面量表达式语法
literal-expressionliteral
literal-expressionarray-literal | dictionary-literal
literal-expression__FILE__ | __LINE__ | __COLUMN__ | __FUNCTION__
array-literal[ array-literal-items opt ]
array-literal-itemsarray-literal-item , opt | array-literal-item , array-literal-items
array-literal-itemexpression
dictionary-literal[ dictionary-literal-items ] | [ : ]
dictionary-literal-itemsdictionary-literal-item , opt | dictionary-literal-item , dictionary-literal-items
dictionary-literal-itemexpression : expression

Self 表达式语法
self-expressionself
self-expressionself . identifier
self-expressionself [ expression ]
self-expressionself . init

超类表达式语法
superclass-expressionsuperclass-method-expression | superclass-subscript-expression | superclass-initializer-expression
superclass-method-expressionsuper . identifier
superclass-subscript-expressionsuper [ expression ]
superclass-initializer-expressionsuper . init

闭包表达式语法
closure-expression{ closure-signature opt statements }
closure-signatureparameter-clause function-result opt in
closure-signatureidentifier-list function-result opt in
closure-signaturecapture-list parameter-clause function-result opt in
closure-signaturecapture-list identifier-list function-result opt in
closure-signaturecapture-list in
capture-list[ capture-specifier expression ]
capture-specifierweak | unowned | unowned(safe) | unowned(unsafe)

隐式成员表达式语法
implicit-member-expression. identifier

带圆括号的表达式语法
parenthesized-expression( expression-element-list opt )
expression-element-listexpression-element | expression-element , expression-element-list
expression-elementexpression | identifier : expression

通配符表达式语法
wildcard-expression_

后缀表达式语法
postfix-expressionprimary-expression
postfix-expressionpostfix-expression postfix-operator
postfix-expressionfunction-call-expression
postfix-expressioninitializer-expression
postfix-expressionexplicit-member-expression
postfix-expressionpostfix-self-expression
postfix-expressiondynamic-type-expression
postfix-expressionsubscript-expression
postfix-expressionforced-value-expression
postfix-expressionoptional-chaining-expression

函数调用表达式语法
function-call-expressionpostfix-expression parenthesized-expression
function-call-expressionpostfix-expression parenthesized-expression opt trailing-closure
trailing-closureclosure-expression

初始化表达式语法
initializer-expressionpostfix-expression . init

显式成员表达式语法
explicit-member-expressionpostfix-expression . decimal-digit
explicit-member-expressionpostfix-expression . identifier generic-argument-clause opt

Self 表达式语法
postfix-self-expressionpostfix-expression . self

动态类型表达式语法
dynamic-type-expressionpostfix-expression . dynamicType

附属脚本表达式语法
subscript-expressionpostfix-expression [ expression-list ]

Forced-value 表达式语法
forced-value-expressionpostfix-expression !

可选链表达式语法
optional-chaining-expressionpostfix-expression ?

词法结构

标识符语法
identifieridentifier-head identifier-characters opt
identifier` identifier-head identifier-characters opt `
identifierimplicit-parameter-name
identifier-listidentifier | identifier , identifier-list
identifier-head → Upper- or lowercase letter A through Z
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-characteridentifier-head
identifier-charactersidentifier-character identifier-characters opt
implicit-parameter-name$ decimal-digits

字面量语法
literalinteger-literal | floating-point-literal | string-literal

整形字面量语法
integer-literalbinary-literal
integer-literaloctal-literal
integer-literaldecimal-literal
integer-literalhexadecimal-literal
binary-literal0b binary-digit binary-literal-characters opt
binary-digit → Digit 0 or 1
binary-literal-characterbinary-digit | _
binary-literal-charactersbinary-literal-character binary-literal-characters opt
octal-literal0o octal-digit octal-literal-characters opt
octal-digit → Digit 0 through 7
octal-literal-characteroctal-digit | _
octal-literal-charactersoctal-literal-character octal-literal-characters opt
decimal-literaldecimal-digit decimal-literal-characters opt
decimal-digit → Digit 0 through 9
decimal-digitsdecimal-digit decimal-digits opt
decimal-literal-characterdecimal-digit | _
decimal-literal-charactersdecimal-literal-character decimal-literal-characters opt
hexadecimal-literal0x hexadecimal-digit hexadecimal-literal-characters opt
hexadecimal-digit → Digit 0 through 9, a through f, or A through F
hexadecimal-literal-characterhexadecimal-digit | _
hexadecimal-literal-charactershexadecimal-literal-character hexadecimal-literal-characters opt

浮点型字面量语法
floating-point-literaldecimal-literal decimal-fraction opt decimal-exponent opt
floating-point-literalhexadecimal-literal hexadecimal-fraction opt hexadecimal-exponent
decimal-fraction. decimal-literal
decimal-exponentfloating-point-e sign opt decimal-literal
hexadecimal-fraction. hexadecimal-literal opt
hexadecimal-exponentfloating-point-p sign opt hexadecimal-literal
floating-point-ee | E
floating-point-pp | P
sign+ | -

字符型字面量语法
string-literal" quoted-text "
quoted-textquoted-text-item quoted-text opt
quoted-text-itemescaped-character
quoted-text-item( expression )
quoted-text-item → Any Unicode extended grapheme cluster except "­, \­, U+000A, or U+000D
escaped-character\0 | \ | \t | \n | \r | \" | \'
escaped-character\x hexadecimal-digit hexadecimal-digit
escaped-character\u hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
escaped-character\U hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit

运算符语法语法
operatoroperator-character operator opt
operator-character/ | = | - | + | ! | * | % | < | > | & | | | ^ | ~ | .
binary-operatoroperator
prefix-operatoroperator
postfix-operatoroperator

类型

类型语法
typearray-type | function-type | type-identifier | tuple-type | optional-type | implicitly-unwrapped-optional-type | protocol-composition-type | metatype-type

类型标注语法
type-annotation: attributes opt type

类型标识语法
type-identifiertype-name generic-argument-clause opt | type-name generic-argument-clause opt . type-identifier
type-nameidentifier

元组类型语法
tuple-type( tuple-type-body opt )
tuple-type-bodytuple-type-element-list ... opt
tuple-type-element-listtuple-type-element | tuple-type-element , tuple-type-element-list
tuple-type-elementattributes opt inout opt type | inout opt element-name type-annotation
element-nameidentifier

函数类型语法
function-typetype -> type

数组类型语法
array-typetype [ ] | array-type [ ]

可选类型语法
optional-typetype ?

隐式解析可选类型语法
implicitly-unwrapped-optional-typetype !

协议合成类型语法
protocol-composition-typeprotocol < protocol-identifier-list opt >
protocol-identifier-listprotocol-identifier | protocol-identifier , protocol-identifier-list
protocol-identifiertype-identifier

元类型语法
metatype-typetype . Type | type . Protocol

类型继承子句语法
type-inheritance-clause: type-inheritance-list
type-inheritance-listtype-identifier | type-identifier , type-inheritance-list

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