ruby 符号(语法)可以包含什么? [英] What can a ruby symbol (syntax) contain?

问题描述

我想创建正则表达式来匹配 ruby​​ 符号，但我需要知道符号的确切语法是什么.

I want to create regular expression to match ruby symbols, but I need to know what the exact syntax for a symbol is.

到目前为止，我知道以下几点:

Until now I am aware of the following:

:'string'
:"string"
:__underline
:method
:exclamation!
:question?
:@instance
:$global

推荐答案

你在说什么不是很清楚.

It's not entirely clear what you are talking about.

如果您在谈论 Symbol 可以包含什么，答案是:任何东西，包括换行符、任意空白、控制字符、任意奇怪和晦涩难懂的 Unicode 字符，以及其他所有内容.

If you are talking about what a Symbol can contain, the answer is: anything and everything, including newlines, arbitrary whitespace, control characters, arbitrarily weird and obscure Unicode characters, and everything else.

如果您在谈论编写 Symbol 文字的各种方式，以下是我最好的理解:

If you are talking about the various ways of writing Symbol literals, here's my best understanding:

• bare : 文字:任何有效的 Ruby 标识符(例如 :foo、:Foo、:@foo, :@@foo, :$foo, :$:, ...)
• 单引号 : 文字:在单引号 String 文字中有效的所有内容，包括转义序列，例如 :'\'' 和 :'\\'
• 双引号 : 字面量:双引号 String 字面量中有效的所有内容，包括转义序列，例如 :"\""、:"\\" 和 :"\n"，以及字符串插值，它允许您将任意 Ruby 代码的结果注入 符号，例如:"#{if rand <;0.5 然后 RUBY_VERSION else ENV['HOME'] end}"
• 单引号 Array 的 Symbol 字面量:在 String 的单引号 Array 中有效的所有内容>s 文字，例如%i|foo bar baz| (相当于[:foo, :bar, :baz]), %i(foo\ bar baz)(相当于[:'foo bar', :baz])，%i:foo bar:(相当于[:foo, :bar])
• 双引号 Array 的 Symbol 字面量:在 StringArray 中有效的所有内容>s 文字，例如%I|foo #{bar} baz| 等
• Symbol key: value 语法中的散列键:每个有效的 Ruby 标签，例如{foo: 42}
• Symbol 引用的 'key': value 语法中的哈希键:每个有效的 Ruby String 文字，包括转义序列和插值，例如{"foo\n#{bar}": 42}

• bare : literal: any valid Ruby identifier (e.g. :foo, :Foo, :@foo, :@@foo, :$foo, :$:, …)
• single-quoted : literal: everything that's valid in a single-quoted String literal, including escape sequences such as :'\'' and :'\\'
• double-quoted : literal: everything that's valid in a double-quoted String literal, including escape sequences such as :"\"", :"\\", and :"\n", as well as string interpolation, which allows you to inject the results of arbitrary Ruby code into the Symbol, e.g. :"#{if rand < 0.5 then RUBY_VERSION else ENV['HOME'] end}"
• single-quoted Array of Symbols literal: everything that's valid in a single-quoted Array of Strings literal, e.g. %i|foo bar baz| (equivalent to [:foo, :bar, :baz]), %i(foo\ bar baz) (equivalent to [:'foo bar', :baz]), %i:foo bar: (equivalent to [:foo, :bar])
• double-quoted Array of Symbols literal: everything that's valid in a double-quoted Array of Strings literal, e.g. %I|foo #{bar} baz|, etc.
• Symbol hash keys in the key: value syntax: every valid Ruby label, e.g. {foo: 42}
• Symbol hash keys in the quoted 'key': value syntax: every valid Ruby String literal, including escape sequences and interpolation, e.g. {"foo\n#{bar}": 42}

当然还有很多其他表达式的计算结果为 Symbols:

There are of course a lot of other expressions that evaluate to Symbols:

• 方法定义表达式:def foo;end # =>:foo
• String#to_sym(别名 String#intern):'foo bar'.to_sym # =>:'foo bar'
• 真的，任何方法可以返回一个Symbol

• method definition expressions: def foo;end # => :foo
• String#to_sym (alias String#intern): 'foo bar'.to_sym # => :'foo bar'
• really, any method that may return a Symbol

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