超能力:仅当字符串开始一行时才将字符串与解析器匹配 [英] Superpower: match a string with parser only if it begins a line

问题描述

超能力解析时，如何只匹配一行中的第一个字符串?

When parsing in superpower, how to match a string only if it is the first thing in a line?

例如，我需要匹配 "A: Hello Goodbye\n" 中的 A 冒号，而不是 "Goodbye A: Hello\n" 中的冒号

For example, I need to match the A colon in "A: Hello Goodbye\n" but not in "Goodbye A: Hello\n"

推荐答案

使用您的示例 此处，我会将您的 ActorParser 和 NodeParser 定义更改为:

Using your example here, I would change your ActorParser and NodeParser definitions to this:

public readonly static TokenListParser<Tokens, Node> ActorParser =
    from name in NameParser
    from colon in Token.EqualTo(Tokens.Colon)
    from text in TextParser
    select new Node {
        Actor = name + colon.ToStringValue(),
        Text = text
    };

public readonly static TokenListParser<Tokens, Node> NodeParser =
    from node in ActorParser.Try()
        .Or(TextParser.Select(text => new Node { Text = text }))
    select node;

我觉得 Superpower 有一个错误，因为我不确定为什么在 NodeParser 中我必须在第一个解析器上放置一个 Try()用 Or() 链接它，但如果我不添加它会抛出错误.

I feel like there is a bug with Superpower, as I'm not sure why in the NodeParser I had to put a Try() on the first parser when chaining it with an Or(), but it would throw an error if I didn't add it.

此外，您在检查 input[1] 时的验证不正确(可能只是复制粘贴问题).它应该检查 "Goodbye A: Hello" 而不是 "Hello A: Goodbye"

Also, your validation when checking input[1] is incorrect (probably just a copy paste issue). It should be checking against "Goodbye A: Hello" and not "Hello A: Goodbye"

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