class Sass::Tree::MixinNode

def _cssize(extends, parent)
  children.map do |c|
    parent.check_child! c
    c.cssize(extends, parent)
  end.flatten
rescue Sass::SyntaxError => e
  e.modify_backtrace(:mixin => @name, :filename => filename, :line => line)
  e.add_backtrace(:filename => filename, :line => line)
  raise e
end

def cssize(extends, parent = nil)
  _cssize(extends, parent) # Pass on the parent even if it's not a MixinNode
end

def handle_include_loop!(environment)
  msg = "An @include loop has been found:"
  mixins = environment.stack.map {|s| s[:mixin]}.compact
  if mixins.size == 2 && mixins[0] == mixins[1]
    raise Sass::SyntaxError.new("#{msg} #{@name} includes itself")
  end
  mixins << @name
  msg << "\n" << Haml::Util.enum_cons(mixins, 2).map do |m1, m2|
    "    #{m1} includes #{m2}"
  end.join("\n")
  raise Sass::SyntaxError.new(msg)
end

def initialize(name, args)
  @name = name
  @args = args
  super()
end

def invalid_child?(child)
  super unless child.is_a?(ExtendNode)
end

def options=(opts)
  super
  @args.each {|a| a.context = :equals} if opts[:sass2]
end

def perform!(environment)
  handle_include_loop!(environment) if environment.mixins_in_use.include?(@name)
  original_env = environment
  original_env.push_frame(:filename => filename, :line => line)
  original_env.prepare_frame(:mixin => @name)
  raise Sass::SyntaxError.new("Undefined mixin '#{@name}'.") unless mixin = environment.mixin(@name)
  raise Sass::SyntaxError.new(<<END.gsub("\n", "")) if mixin.args.size < @args.size
n #{@name} takes #{mixin.args.size} argument#{'s' if mixin.args.size != 1}
 #{@args.size} #{@args.size == 1 ? 'was' : 'were'} passed.
  environment = mixin.args.zip(@args).
    inject(Sass::Environment.new(mixin.environment)) do |env, ((var, default), value)|
    env.set_local_var(var.name,
      if value
        value.perform(environment)
      elsif default
        val = default.perform(env)
        if default.context == :equals && val.is_a?(Sass::Script::String)
          val = Sass::Script::String.new(val.value)
        end
        val
      end)
    raise Sass::SyntaxError.new("Mixin #{@name} is missing parameter #{var.inspect}.") unless env.var(var.name)
    env
  end
  self.children = mixin.tree.map {|c| c.perform(environment)}.flatten
rescue Sass::SyntaxError => e
  if original_env # Don't add backtrace info if this is an @include loop
    e.modify_backtrace(:mixin => @name, :line => @line)
    e.add_backtrace(:line => @line)
  end
  raise e
ensure
  original_env.pop_frame if original_env
end

def to_src(tabs, opts, fmt)
  args = '(' + @args.map {|a| a.to_sass(opts)}.join(", ") + ')' unless @args.empty?
  "#{'  ' * tabs}#{fmt == :sass ? '+' : '@include '}#{dasherize(@name, opts)}#{args}#{semi fmt}\n"
end