Parse indentation level with PEG.js

Question

I have essentially the same question as PEG for Python style indentation, but I\'d like to get a little more direction regarding this answer.

The answer successfully gen

Answer 1

This example uses the colon (:) in order to separate between an object and a simple letter. That way it can also end with an object, but the colon is required. Like the example in the question it does not take care of ignorable whitespaces (eg. before a colon). It is based on Jakubs Kulhans´ example:

// do not use result cache, nor line and column tracking

{ var indentStack = [], indent = ""; }

Start = Object

Object = Block / Letterline

Block = Samedent id:Letter ':' childs:(
    Newline Indent childs:Object* Dedent {return childs;}
)* {
    if (childs) {
        var o = {}; o[id] = childs.flat().flat();
        return o;
    } else {
        return id;
    }
}

Letterline = Samedent letters:Letter+ Newline? {return letters;}

Letter = [a-z]

Newline = "\r\n" / "\n" / "\r"

Indent = &(
    i:[ ]+ &{
        return i.length > indent.length;
    } {
        indentStack.push(indent);
        indent = i.join("");
    }
)

Samedent = i:[ ]* &{ return i.join("") === indent; }

Dedent = &{ indent = indentStack.pop(); return true; }

The grammar will produce the desired output for the following input:

a:
  bc
  d:
    zy
    x: