exc

defmodule Helpers.ASTTraveler do
    @moduledoc """
    Travels through an Abstract Syntax Tree.
    """ 

    @doc """
    Returns a string that results from the traveling of the Abstract Syntax Tree.
    ## Specs  
    ```root```  : abstract syntax tree. An example of an AST is the output from `Parser.parse/2`.

    ```num```   : number of iteration; when calling this function, its value should always be 0. 
    """
    def travel(root, num) do
        if num == 0, do: "{#{root.tag} => {#{decide(root)}}}"
        Enum.map(root.children, fn x -> if x.children == [], do: "\n" <> String.duplicate("\t", num + 1) <> "{#{x.tag} => #{x.token.expression}}", else: "\n" <> String.duplicate("\t", num + 1) <> "{#{x.tag} => #{decide(x)}}" <> "#{travel(x, num + 1)}" end)
    end
    defp decide(node) do 
        if node.token == nil, do: "", else: node.token.expression
    end
end