diff --git a/source/chapter3/02_Lexical_Structure.md b/source/chapter3/02_Lexical_Structure.md index e9e3b822..67febb0b 100644 --- a/source/chapter3/02_Lexical_Structure.md +++ b/source/chapter3/02_Lexical_Structure.md @@ -33,55 +33,31 @@ Swift 的“词法结构（*lexical structure*）”描述了如何在该语言 闭包（*closure*）中如果没有明确指定参数名称，参数将被隐式命名为 $0、$1、$2... 这些命名在闭包作用域内是合法的标识符。 -> 标识符语法 -> -> *identifier* → [identifier-head­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-head) [identifier-characters](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-characters)­ *opt* -> -> *identifier* → \`­ [identifier-head­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-head) [identifier-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-characters) *opt­* \`­ -> -> *identifier* → [implicit-parameter-name­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/implicit-parameter-name) -> -> *identifier-list* → [identifier­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier) | [identifier­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier) , [­identifier-list](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-list)­ -> -> *identifier-head* → A 到 Z 大写或小写字母 -> -> *identifier-head* → U+00A8, U+00AA, U+00AD, U+00AF, U+00B2–U+00B5, 或 U+00B7–U+00BA -> -> *identifier-head* → U+00BC–U+00BE, U+00C0–U+00D6, U+00D8–U+00F6, 或 U+00F8–U+00FF -> -> *identifier-head* → U+0100–U+02FF, U+0370–U+167F, U+1681–U+180D, 或 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, 或 U+2060–U+206F -> -> *identifier-head* → U+2070–U+20CF, U+2100–U+218F, U+2460–U+24FF, 或 U+2776–U+2793 -> -> *identifier-head* → U+2C00–U+2DFF 或 U+2E80–U+2FFF -> -> *identifier-head* → U+3004–U+3007, U+3021–U+302F, U+3031–U+303F, 或 U+3040–U+D7FF -> -> *identifier-head* → U+F900–U+FD3D, U+FD40–U+FDCF, U+FDF0–U+FE1F, 或 U+FE30–U+FE44 -> -> *identifier-head* → U+FE47–U+FFFD -> -> *identifier-head* → U+10000–U+1FFFD, U+20000–U+2FFFD, U+30000–U+3FFFD, 或 U+40000–U+4FFFD -> -> *identifier-head* → U+50000–U+5FFFD, U+60000–U+6FFFD, U+70000–U+7FFFD, 或 U+80000–U+8FFFD -> -> *identifier-head* → U+90000–U+9FFFD, U+A0000–U+AFFFD, U+B0000–U+BFFFD, 或 U+C0000–U+CFFFD -> -> *identifier-head* → U+D0000–U+DFFFD 或 U+E0000–U+EFFFD -> -> *identifier-character* → 数字 0 到 9 -> -> *identifier-character* → U+0300–U+036F, U+1DC0–U+1DFF, U+20D0–U+20FF, or U+FE20–U+FE2F -> -> *identifier-character* → [identifier-head­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-head) -> -> *identifier-characters* → [identifier-character](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-character) [­identifier-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/identifier-characters) *opt­* -> -> *implicit-parameter-name* → **$­** [decimal-digits­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-digits) +> 标识符语法 +> *标识符* → [*标识符头(Head)*](LexicalStructure.html#identifier_head) [*标识符字符列表*](LexicalStructure.html#identifier_characters) _可选_ +> *标识符* → **`** [*标识符头(Head)*](LexicalStructure.html#identifier_head) [*标识符字符列表*](LexicalStructure.html#identifier_characters) _可选_ **`** +> *标识符* → [*隐式参数名*](LexicalStructure.html#implicit_parameter_name) +> *标识符列表* → [*标识符*](LexicalStructure.html#identifier) | [*标识符*](LexicalStructure.html#identifier) **,** [*标识符列表*](LexicalStructure.html#identifier_list) +> *标识符头(Head)* → Upper- or lowercase letter A through Z +> *标识符头(Head)* → U+00A8, U+00AA, U+00AD, U+00AF, U+00B2–U+00B5, or U+00B7–U+00BA +> *标识符头(Head)* → U+00BC–U+00BE, U+00C0–U+00D6, U+00D8–U+00F6, or U+00F8–U+00FF +> *标识符头(Head)* → U+0100–U+02FF, U+0370–U+167F, U+1681–U+180D, or U+180F–U+1DBF +> *标识符头(Head)* → U+1E00–U+1FFF +> *标识符头(Head)* → U+200B–U+200D, U+202A–U+202E, U+203F–U+2040, U+2054, or U+2060–U+206F +> *标识符头(Head)* → U+2070–U+20CF, U+2100–U+218F, U+2460–U+24FF, or U+2776–U+2793 +> *标识符头(Head)* → U+2C00–U+2DFF or U+2E80–U+2FFF +> *标识符头(Head)* → U+3004–U+3007, U+3021–U+302F, U+3031–U+303F, or U+3040–U+D7FF +> *标识符头(Head)* → U+F900–U+FD3D, U+FD40–U+FDCF, U+FDF0–U+FE1F, or U+FE30–U+FE44 +> *标识符头(Head)* → U+FE47–U+FFFD +> *标识符头(Head)* → U+10000–U+1FFFD, U+20000–U+2FFFD, U+30000–U+3FFFD, or U+40000–U+4FFFD +> *标识符头(Head)* → U+50000–U+5FFFD, U+60000–U+6FFFD, U+70000–U+7FFFD, or U+80000–U+8FFFD +> *标识符头(Head)* → U+90000–U+9FFFD, U+A0000–U+AFFFD, U+B0000–U+BFFFD, or U+C0000–U+CFFFD +> *标识符头(Head)* → U+D0000–U+DFFFD or U+E0000–U+EFFFD +> *标识符字符* → 数值 0 到 9 +> *标识符字符* → U+0300–U+036F, U+1DC0–U+1DFF, U+20D0–U+20FF, or U+FE20–U+FE2F +> *标识符字符* → [*标识符头(Head)*](LexicalStructure.html#identifier_head) +> *标识符字符列表* → [*标识符字符*](LexicalStructure.html#identifier_character) [*标识符字符列表*](LexicalStructure.html#identifier_characters) _可选_ +> *隐式参数名* → **$** [*十进制数字列表*](LexicalStructure.html#decimal_digits) ## 关键字 @@ -89,11 +65,8 @@ Swift 的“词法结构（*lexical structure*）”描述了如何在该语言 被保留的关键字（*keywords*）不允许用作标识符，除非被反引号转义，参见 [标识符](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/doc/uid/TP40014097-CH30-XID_796)。 * **用作声明的关键字：** *class*、*deinit*、*enum*、*extension*、*func*、*import*、*init*、*let*、*protocol*、*static*、*struct*、*subscript*、*typealias*、*var* - * **用作语句的关键字：** *break*、*case*、*continue*、*default*、*do*、*else*、*fallthrough*、*if*、*in*、*for*、*return*、*switch*、*where*、*while* - * **用作表达和类型的关键字：** *as*、*dynamicType*、*is*、*new*、*super*、*self*、*Self*、*Type*、*\_\_COLUMN\_\_*、*\_\_FILE\_\_*、*\_\_FUNCTION\_\_*、*\_\_LINE\_\_* - * **特定上下文中被保留的关键字：** *associativity*、*didSet*、*get*、*infix*、*inout*、*left*、*mutating*、*none*、*nonmutating*、*operator*、*override*、*postfix*、*precedence*、*prefix*、*right*、*set*、*unowned*、*unowned(safe)*、*unowned(unsafe)*、*weak*、*willSet*，这些关键字在特定上下文之外可以被用于标识符。 @@ -107,9 +80,8 @@ Swift 的“词法结构（*lexical structure*）”描述了如何在该语言 "Hello, world!" // 文本型字面量 ``` -> 字面量语法 -> -> *literal* → [integer-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/integer-literal) | [floating-point-literal](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/floating-point-literal)­ | [string-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/string-literal) +> 字面量语法 +> *字面量* → [*整型字面量*](LexicalStructure.html#integer_literal) | [*浮点数字面量*](LexicalStructure.html#floating_point_literal) | [*字符串字面量*](LexicalStructure.html#string_literal) ### 整型字面量 @@ -128,49 +100,28 @@ Swift 的“词法结构（*lexical structure*）”描述了如何在该语言 除非特殊指定，整型字面量的默认类型为 Swift 标准库类型中的 `Int`。Swift 标准库还定义了其他不同长度以及是否带符号的整数类型，请参考 [整数类型](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/TheBasics.html#//apple_ref/doc/uid/TP40014097-CH5-XID_411)。 -> 整型字面量语法 -> -> *integer-literal* → [binary-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/binary-literal) -> -> *integer-literal* → [octal-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/octal-literal) -> -> *integer-literal* → [decimal-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-literal) -> -> *integer-literal* → [hexadecimal-literal](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-literal)­ -> -> *binary-literal* → **0b**­ [binary-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/binary-digit) ­[binary-literal-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/binary-literal-characters) *opt­* -> -> *binary-digit* → 数字 0 或 1 -> -> *binary-literal-character* → [binary-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/binary-digit)­ | _­ -> -> *binary-literal-characters* → [binary-literal-character](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/binary-literal-character) ­[binary-literal-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/binary-literal-characters) *opt­* -> -> *octal-literal* → **0o**­ [octal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/octal-digit) ­[octal-literal-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/octal-literal-characters) *opt­* -> -> *octal-digit* → 数字 0 至 7 -> -> *octal-literal-character* → [octal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/octal-digit)­ | _­ -> -> *octal-literal-characters* → [octal-literal-character](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/octal-literal-character) [­octal-literal-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/octal-literal-characters) *opt­* -> -> *decimal-literal* → [decimal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-digit) [­decimal-literal-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-literal-characters) *opt­* -> -> *decimal-digit* → 数字 0 至 9 -> -> *decimal-digits* → [decimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-digit) [decimal-digits­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-digits) *opt­* -> -> *decimal-literal-character* → [decimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-digit) | _­ -> -> *decimal-literal-characters* → [decimal-literal-character](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-literal-character) ­[decimal-literal-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-literal-characters) *opt­* -> -> *hexadecimal-literal* → **0x** ­[hexadecimal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [­hexadecimal-literal-characters­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-literal-characters) *opt­* -> -> *hexadecimal-digit* → 数字 0 到 9, a 到 f, 或 A 到 F -> -> *hexadecimal-literal-character* → [hexadecimal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit)­ | _­ -> -> *hexadecimal-literal-characters* → [hexadecimal-literal-character­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-literal-character) [hexadecimal-literal-characters](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-literal-characters) ­*opt­* +> 整型字面量语法 +> *整型字面量* → [*二进制字面量*](LexicalStructure.html#binary_literal) +> *整型字面量* → [*八进制字面量*](LexicalStructure.html#octal_literal) +> *整型字面量* → [*十进制字面量*](LexicalStructure.html#decimal_literal) +> *整型字面量* → [*十六进制字面量*](LexicalStructure.html#hexadecimal_literal) +> *二进制字面量* → **0b** [*二进制数字*](LexicalStructure.html#binary_digit) [*二进制字面量字符列表*](LexicalStructure.html#binary_literal_characters) _可选_ +> *二进制数字* → 数值 0 到 1 +> *二进制字面量字符* → [*二进制数字*](LexicalStructure.html#binary_digit) | **_** +> *二进制字面量字符列表* → [*二进制字面量字符*](LexicalStructure.html#binary_literal_character) [*二进制字面量字符列表*](LexicalStructure.html#binary_literal_characters) _可选_ +> *八进制字面量* → **0o** [*八进字数字*](LexicalStructure.html#octal_digit) [*八进制字符列表*](LexicalStructure.html#octal_literal_characters) _可选_ +> *八进字数字* → 数值 0 到 7 +> *八进制字符* → [*八进字数字*](LexicalStructure.html#octal_digit) | **_** +> *八进制字符列表* → [*八进制字符*](LexicalStructure.html#octal_literal_character) [*八进制字符列表*](LexicalStructure.html#octal_literal_characters) _可选_ +> *十进制字面量* → [*十进制数字*](LexicalStructure.html#decimal_digit) [*十进制字符列表*](LexicalStructure.html#decimal_literal_characters) _可选_ +> *十进制数字* → 数值 0 到 9 +> *十进制数字列表* → [*十进制数字*](LexicalStructure.html#decimal_digit) [*十进制数字列表*](LexicalStructure.html#decimal_digits) _可选_ +> *十进制字符* → [*十进制数字*](LexicalStructure.html#decimal_digit) | **_** +> *十进制字符列表* → [*十进制字符*](LexicalStructure.html#decimal_literal_character) [*十进制字符列表*](LexicalStructure.html#decimal_literal_characters) _可选_ +> *十六进制字面量* → **0x** [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制字面量字符列表*](LexicalStructure.html#hexadecimal_literal_characters) _可选_ +> *十六进制数字* → 数值 0 到 9, a through f, or A through F +> *十六进制字符* → [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) | **_** +> *十六进制字面量字符列表* → [*十六进制字符*](LexicalStructure.html#hexadecimal_literal_character) [*十六进制字面量字符列表*](LexicalStructure.html#hexadecimal_literal_characters) _可选_ ### 浮点型字面量 @@ -193,33 +144,24 @@ Swift 的“词法结构（*lexical structure*）”描述了如何在该语言 除非特殊指定，浮点型字面量的默认类型为 Swift 标准库类型中的 `Double`，表示64位浮点数。Swift 标准库也定义 `Float` 类型，表示32位浮点数。 -> 浮点型字面量语法 -> -> *floating-point-literal* → [decimal-literal](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-literal) ­[decimal-fraction­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-fraction) *opt* ­[decimal-exponent­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-exponent) *opt­* -> -> *floating-point-literal* → [hexadecimal-literal](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-literal) ­[hexadecimal-fraction](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-fraction) ­*opt­* [hexadecimal-exponent](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-exponent)­ -> -> *decimal-fraction* → . [­decimal-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-literal) -> -> *decimal-exponent* → [floating-point-e](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/floating-point-e) [­sign­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/sign) *opt­* [decimal-literal](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/decimal-literal)­ -> -> *hexadecimal-fraction* → . [­hexadecimal-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-literal) *opt­* -> -> *hexadecimal-exponent* → [floating-point-p­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/floating-point-p) [sign­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/sign) *opt­* [hexadecimal-literal­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-literal) -> -> *floating-point-e* → **e­** | **E**­ -> -> *floating-point-p* → **p**­ | **P**­ -> -> *sign* → **+**­ | **-**­ - - +> 浮点型字面量语法 +> *浮点数字面量* → [*十进制字面量*](LexicalStructure.html#decimal_literal) [*十进制分数*](LexicalStructure.html#decimal_fraction) _可选_ [*十进制指数*](LexicalStructure.html#decimal_exponent) _可选_ +> *浮点数字面量* → [*十六进制字面量*](LexicalStructure.html#hexadecimal_literal) [*十六进制分数*](LexicalStructure.html#hexadecimal_fraction) _可选_ [*十六进制指数*](LexicalStructure.html#hexadecimal_exponent) +> *十进制分数* → **.** [*十进制字面量*](LexicalStructure.html#decimal_literal) +> *十进制指数* → [*浮点数e*](LexicalStructure.html#floating_point_e) [*正负号*](LexicalStructure.html#sign) _可选_ [*十进制字面量*](LexicalStructure.html#decimal_literal) +> *十六进制分数* → **.** [*十六进制字面量*](LexicalStructure.html#hexadecimal_literal) _可选_ +> *十六进制指数* → [*浮点数p*](LexicalStructure.html#floating_point_p) [*正负号*](LexicalStructure.html#sign) _可选_ [*十六进制字面量*](LexicalStructure.html#hexadecimal_literal) +> *浮点数e* → **e** | **E** +> *浮点数p* → **p** | **P** +> *正负号* → **+** | **-** ### 文本型字面量 文本型字面量（*string literal*）由双引号中的字符串组成，形式如下： - "characters" +```swift +"characters" +``` 文本型字面量中不能包含未转义的双引号 `"`、未转义的反斜线`\`、回车符（*carriage return*）或换行符（*line feed*）。 @@ -254,25 +196,16 @@ var x = 3; "1 2 \(x)" 文本型字面量的默认类型为 `String`。组成字符串的字符类型为 `Character`。更多有关 `String` 和 `Character` 的信息请参照 [字符串和字符](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/StringsAndCharacters.html#//apple_ref/doc/uid/TP40014097-CH7-XID_368)。 -> 文本型字面量语法 -> -> *string-literal* → **"­** [quoted-text](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/quoted-text) **­"­** -> -> *quoted-text* → [quoted-text-item­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/quoted-text-item) [quoted-text](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/quoted-text) ­*opt­* -> -> *quoted-text-item* → [escaped-character­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/escaped-character) -> -> *quoted-text-item* → **\(**­ [expression­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/swift/grammar/expression) **)**­ -> -> *quoted-text-item* → 除 `"`、`\`­、`U+000A` 或 `U+000D` 以外的任何 Unicode 扩展字符集 -> -> *escaped-character* → **\0­** | **\\**­ | **\t­** | **\n**­ | **\r­** | **\"­** | **\'**­ -> -> *escaped-character* → **\x­** [hexadecimal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit)­ [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) -> -> *escaped-character* → **\u** ­[hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [­hexadecimal-digit](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit)­ [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) -> -> *escaped-character* → **\U­** [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) [hexadecimal-digit­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/hexadecimal-digit) +> 字符型字面量语法 +> *字符串字面量* → **"** [*引用文本*](LexicalStructure.html#quoted_text) **"** +> *引用文本* → [*引用文本条目*](LexicalStructure.html#quoted_text_item) [*引用文本*](LexicalStructure.html#quoted_text) _可选_ +> *引用文本条目* → [*转义字符*](LexicalStructure.html#escaped_character) +> *引用文本条目* → **\(** [*表达式*](..\chapter3\04_Expressions.html#expression) **)** +> *引用文本条目* → 除了"­, \­, U+000A, or U+000D的所有Unicode的字符 +> *转义字符* → **\0** | **\\** | **\t** | **\n** | **\r** | **\"** | **\'** +> *转义字符* → **\x** [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) +> *转义字符* → **\u** [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) +> *转义字符* → **\U** [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) [*十六进制数字*](LexicalStructure.html#hexadecimal_digit) ## 运算符 @@ -285,11 +218,8 @@ Swift 标准库定义了许多可供使用的运算符，其中大部分在 [基 运算符两侧的空白被用来区分该运算符是否为前缀运算符（*prefix operator*）、后缀运算符（*postfix operator*）或二元运算符（*binary operator*）。规则总结如下： * 如果运算符两侧都有空白或两侧都无空白，将被看作二元运算符。例如：`a+b` 和 `a + b` 中的运算符 `+` 被看作二元运算符。 - * 如果运算符只有左侧空白，将被看作前缀一元运算符。例如 `a ++b` 中的 `++` 被看作前缀一元运算符。 - * 如果运算符只有右侧空白，将被看作后缀一元运算符。例如 `a++ b` 中的 `++` 被看作后缀一元运算符。 - * 如果运算符左侧没有空白并紧跟 `.`，将被看作后缀一元运算符。例如 `a++.b` 中的 `++` 被看作后缀一元运算符（同理， `a++ . b` 中的 `++` 是后缀一元运算符而 `a ++ .b` 中的 `++` 不是）. 鉴于这些规则，运算符前的字符 `(`、`[` 和 `{` ；运算符后的字符 `)`、`]` 和 `}` 以及字符 `,`、`;` 和 `:` 都将用于空白检测。 @@ -300,14 +230,9 @@ Swift 标准库定义了许多可供使用的运算符，其中大部分在 [基 要学习如何自定义新的运算符，请参考 [自定义操作符](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/AdvancedOperators.html#//apple_ref/doc/uid/TP40014097-CH27-XID_48) 和 [运算符声明](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/doc/uid/TP40014097-CH34-XID_644)。学习如何重写现有运算符，请参考 [运算符方法](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/AdvancedOperators.html#//apple_ref/doc/uid/TP40014097-CH27-XID_43)。 -> 运算符语法 -> -> *operator* → [operator-character­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/operator-character) [operator­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/operator) *opt­* -> -> *operator-character* → **/­** | **=­** | **-­** | **+­** | **!­** | ***­** | **%­** | **<­** | **>­** | **&­** | **|­** | **^­** | **~­** | **.­** -> -> *binary-operator* → [operator­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/operator) -> -> *prefix-operator* → [operator­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/operator) -> -> *postfix-operator* → [operator­](https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/LexicalStructure.html#//apple_ref/swift/grammar/operator) +> 运算符语法语法 +> *运算符* → [*运算符字符*](LexicalStructure.html#operator_character) [*运算符*](LexicalStructure.html#operator) _可选_ +> *运算符字符* → **/** | **=** | **-** | **+** | **!** | ***** | **%** | **<** | **>** | **&** | **|** | **^** | **~** | **.** +> *二元运算符* → [*运算符*](LexicalStructure.html#operator) +> *前置运算符* → [*运算符*](LexicalStructure.html#operator) +> *后置运算符* → [*运算符*](LexicalStructure.html#operator)