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("Mixin \#{@name} takes \#{mixin.args.size} argument\#{'s' if mixin.args.size != 1}\n but \#{@args.size} \#{@args.size == 1 ? 'was' : 'were'} passed.\n".gsub("\n", "")) if mixin.args.size < @args.size
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
e.modify_backtrace(:mixin => @name, :line => @line)
e.add_backtrace(:line => @line)
end
raise e
ensure
original_env.pop_frame if original_env
end