state = start
    transition = transition-for (state, input.current-char)
    
    if (transition.is-good) {
        state = transition.state                # move
        
        if (state.accepts) {                    # memo
            memo.type = state.type
            memo.position = input.position
        }
        advance (input)                         # advance
    } else {
        push (output-queue, token (memo.type))  # token
        input.position = memo.position          # rewind
        state = start                           # restart
    }