module ActiveSupport::LazyLoadHooks

def self.extended(base) # :nodoc:
  base.class_eval do
    @load_hooks = Hash.new { |h, k| h[k] = [] }
    @loaded     = Hash.new { |h, k| h[k] = [] }
    @run_once   = Hash.new { |h, k| h[k] = [] }
  end
end

def execute_hook(name, base, options, block)
  with_execution_control(name, block, options[:run_once]) do
    if options[:yield]
      block.call(base)
    else
      base.instance_eval(&block)
    end
  end
end

def on_load(name, options = {}, &block)
  @loaded[name].each do |base|
    execute_hook(name, base, options, block)
  end
  @load_hooks[name] << [block, options]
end

def run_load_hooks(name, base = Object)
  @loaded[name] << base
  @load_hooks[name].each do |hook, options|
    execute_hook(name, base, options, hook)
  end
end

def with_execution_control(name, block, once)
  unless @run_once[name].include?(block)
    @run_once[name] << block if once
    yield
  end
end