在Scala解析器组合器中使用Positional和positioned() [英] Using Positional and positioned() in scala parser combinators

问题描述

具有单独的Lexer和Parser ...

With separate Lexer and Parser ...

class YamlLexical extends StdLexical with YamlTokens with RegexParsers {...
object YamlParser extends StdTokenParsers with YamlTokens with PackratParsers {...

...如何将已解析的字符串的位置放入AST类中?

... how to get the position of the parsed string into AST classes?

(... positioned(elem(...)) * ... )^^ { ... => List( Ast(startpos, parsedtext, ... subnodes ... ), ... )}

推荐答案

positioned的类型为

def positioned[T <: Positional](p: ⇒ Parser[T]): Parser[T]

表示已解析的元素必须扩展Positional.因此，例如，YamlLexical应该是:

which means that the parsed elements must extend Positional. So, for example, YamlLexical should be:

class YamlLexical extends Positional 

以这种方式，任何已解析的元素将自动具有pos，该pos记录了其被解析的位置.

in that way, any parsed element will automatically have a pos which records the position in which it was parsed.

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