In the meantime, let's explore Scala's third option for building parsers: parser combinators, built entirely from the functional side of Scala.

同时，我们来探索Scala构建解析器的第3个选项：解析器组合子(parser combinators)，它完全是从Scala的函数性方面构建的。

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There is, and to understand how it works, you'll need to take a short dive into how parser combinators produce non - "standard" elements (that is, not Strings and Lists).

确实有另外一种方法。为了理解这种方法的工作原理，您将需要研究一下解析器组合子是如何产生非“标准”的元素的(即不是String和List)。

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That's it for now; in the next set of articles, we'll go back to visiting more of Scala's language capabilities (such as generics, because parser combinators made use of them).

本文到此结束。在下一篇文章中，我们将回顾scala的更多语言功能(比如泛型，因为解析器组合子是由它们组成的)。

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Parsers "combine" to provide higher and higher levels of abstraction over the concept of parsing (hence the name "parser combinators"; elements which combine together to provide parsing behavior).

“组合”解析器可以提供解析概念的越来越高级的抽象(因此称为“解析器组合子”；组合在一起的元素提供解析行为)。

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To change it to produce instances of our case class AST hierarchy (Expr objects), the return type of the combinators has to be changed to be Parser[Expr].

要将它更改为生成case类AST层次结构的实例（Expr对象），组合子的返回类型必须更改为Parser[Expr]。

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To change it to produce instances of our case class AST hierarchy (Expr objects), the return type of the combinators has to be changed to be Parser[Expr].

要将它更改为生成case类AST层次结构的实例（Expr对象），组合子的返回类型必须更改为Parser[Expr]。

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