class Thor::CoreExt::OrderedHash

def [](key)
  @hash[key] && @hash[key].value
end

def []=(key, value)
  if node = @hash[key]
    node.value = value
  else
    node = Node.new(key, value)
    if @first.nil?
      @first = @last = node
    else
      node.prev = @last
      @last.next = node
      @last = node
    end
  end
  @hash[key] = node
  value
end

def delete(key)
  if node = @hash[key]
    prev_node = node.prev
    next_node = node.next
    next_node.prev = prev_node if next_node
    prev_node.next = next_node if prev_node
    @first = next_node if @first == node
    @last = prev_node  if @last  == node
    value = node.value
  end
  @hash.delete(key)
  value
end

def each
  return unless @first
  yield [@first.key, @first.value]
  node = @first
  yield [node.key, node.value] while node = node.next
  self
end

def empty?
  @hash.empty?
end

def initialize
  @hash = {}
end

def keys
  self.map { |k, v| k }
end

def merge(other)
  hash = self.class.new
  self.each do |key, value|
    hash[key] = value
  end
  other.each do |key, value|
    hash[key] = value
  end
  hash
end

def values
  self.map { |k, v| v }
end