defmodule Mage do
  @moduledoc false

  def postwalk(ast, fun) do
    walker = fn ast ->
      result_ast = fun.(ast)

      if result_ast == ast do
        ast
      else
        case result_ast do
          {op, meta, args} ->
            {op, Keyword.put(meta, :__patch__, true), args}

          val ->
            val
        end
      end
    end

    Macro.postwalk(ast, walker)
  end

  def to_string(ast) do
    Mage.Code.to_string(ast)
  end

  def parse_string!(source) do
    Mage.Code.parse_string!(source)
  end
end