state->start
    while (config->has_more_input) {
        if (state->attempt_transition_for(config->current_input)) { # move
            config->remember(state->type) if state->accepts         # memo
            config->input->advance                                  # advance
        } else {
            config->rewind                # rewind
            push (output_queue, token {   # token
                type = config->type
                value = config->string
            })
            state->start                  # restart
        }
    }