def visit_mixin(node)
handle_include_loop!(node) if @environment.mixins_in_use.include?(node.name)
original_env = @environment
original_env.push_frame(:filename => node.filename, :line => node.line)
original_env.prepare_frame(:mixin => node.name)
raise Sass::SyntaxError.new("Undefined mixin '#{node.name}'.") unless mixin = @environment.mixin(node.name)
passed_args = node.args.dup
passed_keywords = node.keywords.dup
raise Sass::SyntaxError.new("Mixin \#{node.name} takes \#{mixin.args.size} argument\#{'s' if mixin.args.size != 1}\n but \#{node.args.size} \#{node.args.size == 1 ? 'was' : 'were'} passed.\n".gsub("\n", "")) if mixin.args.size < passed_args.size
passed_keywords.each do |name, value|
unless mixin.args.find {|(var, default)| var.underscored_name == name}
raise Sass::SyntaxError.new("Mixin #{node.name} doesn't have an argument named $#{name}")
end
end
environment = mixin.args.zip(passed_args).
inject(Sass::Environment.new(mixin.environment)) do |env, ((var, default), value)|
env.set_local_var(var.name,
if value
value.perform(@environment)
elsif kv = passed_keywords[var.underscored_name]
kv.perform(@environment)
elsif default
default.perform(env)
end)
raise Sass::SyntaxError.new("Mixin #{node.name} is missing parameter #{var.inspect}.") unless env.var(var.name)
env
end
with_environment(environment) {node.children = mixin.tree.map {|c| visit(c)}.flatten}
node
rescue Sass::SyntaxError => e
if original_env
e.modify_backtrace(:mixin => node.name, :line => node.line)
e.add_backtrace(:line => node.line)
end
raise e
ensure
original_env.pop_frame if original_env
end