class Treetop::Compiler::Choice

def compile_alternatives(alternatives)
  obtain_new_subexpression_address
  alternatives.first.compile(subexpression_address, builder)
  builder.if__ subexpression_success? do
    assign_result subexpression_result_var
    extend_result_with_declared_module
    extend_result_with_inline_module
  end
  builder.else_ do
    if alternatives.size == 1
      reset_index
      assign_failure start_index_var
    else
      compile_alternatives(alternatives[1..-1])
    end
  end
end