标记法

Notation 标记法

原文：https://go.dev/ref/spec#Notation

The syntax is specified using a variant of Extended Backus-Naur Form (EBNF):

​ （标记法的）语法是用 Extended Backus-Naur Form (EBNF) 的一个变体来指定的。

Syntax      = { Production } .
Production  = production_name "=" [ Expression ] "." .
Expression  = Term { "|" Term } .
Term        = Factor { Factor } .
Factor      = production_name | token [ "…" token ] | Group | Option | Repetition .
Group       = "(" Expression ")" .
Option      = "[" Expression "]" .
Repetition  = "{" Expression "}" .

Productions are expressions constructed from terms and the following operators, in increasing precedence:

​ 产生式是由术语和以下运算符构建的表达式，其优先级越来越高。

|   alternation
()  grouping
[]  option (0 or 1 times)
{}  repetition (0 to n times)

Lowercase production names are used to identify lexical (terminal) tokens. Non-terminals are in CamelCase. Lexical tokens are enclosed in double quotes "" or back quotes ``.

​ 小写的产生式名称用于标识词法（终端）标记。非终端则使用CamelCase。词法标记用双引号""或反引号``包裹起来。

The form a … b represents the set of characters from a through b as alternatives. The horizontal ellipsis … is also used elsewhere in the spec to informally denote various enumerations or code snippets that are not further specified. The character … (as opposed to the three characters ...) is not a token of the Go language.

​ a ... b的形式表示从a到b的一组字符作为备选项。在规范的其他地方也使用水平省略号...来非正式地表示各种枚举或没有进一步指定的代码片段。字符…（相对于三个字符...而言）不是Go语言的标记。

A link of the form [Go 1.xx] indicates that a described language feature (or some aspect of it) was changed or added with language version 1.xx and thus requires at minimum that language version to build. For details, see the linked section in the appendix.

​ 表格的链接[Go 1.xx]表示已描述语言功能(或其某些方面)已更改或添加了语言版本1.xx和 因此，至少需要构建该语言版本。 有关详细信息，请参见 链接部分 在 附录。