Question

我正在尝试使用FParsec从s表达式语言解析lisp样式的注释。在前一个帖子中解析单行注释时我得到了一些帮助 - How to convert an FParsec parser to parse whitespace

虽然已经解决了，但仍需要解析多行注释。这是当前的代码 -

/// Read whitespace character as a string.
let spaceAsStr = anyOf whitespaceChars |>> fun chr -> string chr

/// Read a line comment.
let lineComment = pchar lineCommentChar >>. restOfLine true

/// Read a multiline comment.
/// TODO: make multiline comments nest.
let multilineComment =
    between
        (pstring openMultilineCommentStr)
        (pstring closeMultilineCommentStr)
        (charsTillString closeMultilineCommentStr true System.Int32.MaxValue)

/// Read whitespace text.
let whitespace =
    lineComment <|>
    multilineComment <|>
    spaceAsStr

/// Skip any white space characters.
let skipWhitespace = skipMany whitespace

/// Skip at least one white space character.
let skipWhitespace1 = skipMany1 whitespace

不幸的是，multilineComment解析永远不会成功。由于这是一个组合器，我不能提出断点或分析它为什么不起作用。

为什么它不起作用的任何想法？

Answer 1

尝试将closeMultilineCommentStr的bool参数更改为false

(charsTillString closeMultilineCommentStr false System.Int32.MaxValue)

否则会跳过closeMultilineCommentStr字符串。

使其适用于嵌套注释

let rec multilineComment o=
    let ign x = charsTillString x false System.Int32.MaxValue
    between
        (pstring openMultilineCommentStr)
        (pstring closeMultilineCommentStr)
        (attempt (ign openMultilineCommentStr >>. multilineComment >>. ign closeMultilineCommentStr) <|> 
        ign closeMultilineCommentStr) <|o

如何使用FParsec解析注释

1 个答案: