在PEG.js上为STRING.STRING.STRING进行语法表达

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问题描述

我正在寻找与以下对象匹配的peg.js语法表达式:

I am looking for a peg.js grammar expression for matching against:

"variable"#失败
"variable."#失败
""#失败
"variable.variable"#确定
"variable.variable.variable.variable.variable"#确定

"variable" # Fails
"variable." # Fails
"" # Fails
"variable.variable" # Ok
"variable.variable.variable.variable.variable" #Ok

{PATH: "variable.variable"}
{PATH: "variable.variable.variable.variable.variable"}

{PATH: "variable.variable"}
{PATH: "variable.variable.variable.variable.variable"}

start =
    PATH_EXP

STRING_EXP =
    chars:[0-9a-zA-Z_]+ { return chars.join(""); }

PATH_EXP =
    path:(STRING_EXP "." STRING_EXP) { return {PATH: path.join("")}; }

我不知道如何使表达式重复，但也使其成为可选.

I don't know how to make the expression repeat, but also make it optional.

推荐答案

这就是我想出的摆脱."的原因.人物.我承认我以前从未使用过peg.js:)

Here's what I came up with to get rid of the "." characters. I'll admit that I've never used peg.js before :)

PATH_EXP =
    (first:STRING_EXP rest:("." STRING_EXP)*) {
      return {
        PATH: first +
              rest.map(function(v) {
                return v[1];
              }).join("")
      };
    }

edit —哦，等等，这样更好:

edit — oh wait this is better:

PATH_EXP =
    first:STRING_EXP rest:("." s:STRING_EXP { return "." + s; })+ {
      return {
        PATH: first + rest.join('')
      };
    }

edit —清楚地知道是否要使用."您会在第二部分的动作中将其包括在内的字符.错过了那部分问题.

edit — clearly if you want the "." characters you'd include them in the action inside that second part. Missed that part of the question.

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