開(kāi)篇語(yǔ)

今天是筆者奶奶生日，昨天為此準(zhǔn)備了不少事情，也因此花費(fèi)了很多時(shí)間，今天上午接待客人，下午送我年邁的姑奶奶回家。等我抽出身來(lái)看代碼已經(jīng)是三點(diǎn)的事情了。再加上還有個(gè)“問(wèn)題xx”要教導(dǎo)，真正開(kāi)始認(rèn)真看代碼，已經(jīng)是四點(diǎn)咯。然后看到五點(diǎn)多，爸爸叫我吃飯，我去，還沒(méi)跑步，所以又是一番雞飛狗跳。跑完回來(lái)一邊壓腿，一邊看家人吃飯，也是醉醉的。雖然有點(diǎn)跑題，但是我還是要拿我的跑步的圖來(lái)放一放~~~

這是定向越野~地面泥濘，公路上大大小小的石子，跑起來(lái)真是百曲千回~

第二天了，繼續(xù)堅(jiān)持！yeah！

正文

本次是我對(duì)于Python實(shí)現(xiàn)2048這個(gè)曾經(jīng)風(fēng)靡一時(shí)的小游戲的代碼解讀，代碼來(lái)自實(shí)驗(yàn)樓:200行Python代碼實(shí)現(xiàn)2048

工作環(huán)境

一、主邏輯圖

邏輯圖解：黑色是邏輯層，藍(lán)色是外部方法，紅色是類內(nèi)方法，稍后即可知道~

狀態(tài)機(jī)。。。游戲概念，出自實(shí)驗(yàn)樓

下面容我逐行解釋主邏輯main()函數(shù)，并且在其中穿叉外部定義的函數(shù)與類。

二、主邏輯代碼解讀（完整代碼見(jiàn)文末）

主邏輯main如下，之后的是對(duì)主函數(shù)中的一些方法的解讀：

def main(stdscr):
    def init():
        #重置游戲棋盤
        game_field.reset()
        return 'Game'

    def not_game(state):
        #畫出 GameOver 或者 Win 的界面
        game_field.draw(stdscr)
        #讀取用戶輸入得到action，判斷是重啟游戲還是結(jié)束游戲
        action = get_user_action(stdscr)
        responses = defaultdict(lambda: state) #默認(rèn)是當(dāng)前狀態(tài)，沒(méi)有行為就會(huì)一直在當(dāng)前界面循環(huán)
        responses['Restart'], responses['Exit'] = 'Init', 'Exit' #對(duì)應(yīng)不同的行為轉(zhuǎn)換到不同的狀態(tài)
        return responses[action]

    def game():
        #畫出當(dāng)前棋盤狀態(tài)
        game_field.draw(stdscr)
        #讀取用戶輸入得到action
        action = get_user_action(stdscr)

        if action == 'Restart':
            return 'Init'
        if action == 'Exit':
            return 'Exit'
        if game_field.move(action): # move successful
            if game_field.is_win():
                return 'Win'
            if game_field.is_gameover():
                return 'Gameover'
        return 'Game'


    state_actions = {
            'Init': init,
            'Win': lambda: not_game('Win'),
            'Gameover': lambda: not_game('Gameover'),
            'Game': game
        }

    curses.use_default_colors()
    game_field = GameField(win=32)

    state = 'Init'

    #狀態(tài)機(jī)開(kāi)始循環(huán)
    while state != 'Exit':
        state = state_actions[state]()

逐條解讀（代碼框內(nèi)會(huì)標(biāo)注是來(lái)自外部，無(wú)標(biāo)注則是來(lái)自內(nèi)部）：定義主函數(shù)

def main(stdscr):

    def init():
        #重置游戲棋盤
        game_field.reset()

reset出自外部定義的類，game_field=GameField的一個(gè)方法reset：

  外部：
  def reset(self):
        if self.score > self.highscore:
            self.highscore = self.score
        self.score = 0
        self.field = [[0 for i in range(self.width)] for j in range(self.height)]
        self.spawn()
        self.spawn()
#其中highscore為程序初始化過(guò)程中定義的一個(gè)變量。記錄你win游戲的最高分?jǐn)?shù)記錄。

        return 'Game'

返回一個(gè)游戲進(jìn)行中的狀態(tài)。game_field=GameField狀態(tài)在后面有定義：

主函數(shù)底部定義：
 state_actions = {
            'Init': init,
            'Win': lambda: not_game('Win'),
            'Gameover': lambda: not_game('Gameover'),
            'Game': game
        }

    def not_game(state):
        #畫出 GameOver 或者 Win 的界面
        game_field.draw(stdscr)

draw是導(dǎo)入的類game_field=GameField中的方法：

#來(lái)自外部類
    def draw(self, screen):
        help_string1 = '(W)Up (S)Down (A)Left (D)Right'
        help_string2 = '     (R)Restart (Q)Exit'
        gameover_string = '           GAME OVER'
        win_string = '          YOU WIN!'
#定義各個(gè)字符串
        def cast(string):
            screen.addstr(string + '\n')

        def draw_hor_separator():
            line = '+' + ('+------' * self.width + '+')[1:]
            separator = defaultdict(lambda: line)
            if not hasattr(draw_hor_separator, "counter"):
                draw_hor_separator.counter = 0
            cast(separator[draw_hor_separator.counter])
            draw_hor_separator.counter += 1

        def draw_row(row):
            cast(''.join('|{: ^5} '.format(num) if num > 0 else '|      ' for num in row) + '|')

        screen.clear()
        cast('SCORE: ' + str(self.score))
        if 0 != self.highscore:
            cast('HGHSCORE: ' + str(self.highscore))
        for row in self.field:
            draw_hor_separator()
            draw_row(row)
        draw_hor_separator()
        if self.is_win():
            cast(win_string)
        else:
            if self.is_gameover():
                cast(gameover_string)
            else:
                cast(help_string1)
        cast(help_string2)
#這里面的draw方法的字函數(shù)我就不做多的解釋了，很簡(jiǎn)單的一些概念。
#但是又運(yùn)用到了很優(yōu)秀的精簡(jiǎn)代碼。
#有的地方建議去查一下python的一些高級(jí)概念，我就不做多的介紹了。

這里面的draw方法的字函數(shù)我就不做多的解釋了，很簡(jiǎn)單的一些概念。
但是又運(yùn)用到了很優(yōu)秀的精簡(jiǎn)代碼。
有的地方建議去查一下python的一些高級(jí)概念，我就不做多的介紹了。

        #讀取用戶輸入得到action，判斷是重啟游戲還是結(jié)束游戲
        action = get_user_action(stdscr)

讀取用戶行為,函數(shù)來(lái)自于代碼初始的定義

#來(lái)自外部定義的函數(shù)
def get_user_action(keyboard):    
    char = "N"
    while char not in actions_dict:    
        char = keyboard.getch()
    return actions_dict[char]

在結(jié)尾處，也即是主函數(shù)執(zhí)行的第三步，定義了state = state_actions[state]()這一實(shí)例：

#主函數(shù)底部：
    state = 'Init'

    #狀態(tài)機(jī)開(kāi)始循環(huán)
    while state != 'Exit':
        state = state_actions[state]()

        responses = defaultdict(lambda: state) #默認(rèn)是當(dāng)前狀態(tài)，沒(méi)有行為就會(huì)一直在當(dāng)前界面循環(huán)
        responses['Restart'], responses['Exit'] = 'Init', 'Exit' #對(duì)應(yīng)不同的行為轉(zhuǎn)換到不同的狀態(tài)
        return responses[action]

    def game():
        #畫出當(dāng)前棋盤狀態(tài)
        game_field.draw(stdscr)
        #讀取用戶輸入得到action
        action = get_user_action(stdscr)

        if action == 'Restart':
            return 'Init'
        if action == 'Exit':
            return 'Exit'
        if game_field.move(action): # move successful
            if game_field.is_win():
                return 'Win'
            if game_field.is_gameover():
                return 'Gameover'
        return 'Game'
#game()函數(shù)的定義類似于上面已經(jīng)講過(guò)的not_game()，只是game()有了內(nèi)部循環(huán)
#即如果不是Restart/Exit或者對(duì)move之后的狀態(tài)進(jìn)行判斷，如果不是結(jié)束游戲，就一直在game()內(nèi)部循環(huán)。

game()函數(shù)的定義類似于上面已經(jīng)講過(guò)的not_game()，只是game()有了內(nèi)部循環(huán)，即如果不是Restart/Exit或者對(duì)move之后的狀態(tài)進(jìn)行判斷，如果不是結(jié)束游戲，就一直在game()內(nèi)部循環(huán)。

    state_actions = {
            'Init': init,
            'Win': lambda: not_game('Win'),
            'Gameover': lambda: not_game('Gameover'),
            'Game': game
                        }

    curses.use_default_colors()
    game_field = GameField(win=32)


    state = 'Init'

    #狀態(tài)機(jī)開(kāi)始循環(huán)
    while state != 'Exit':
        state = state_actions[state]()
#此處的意思是：state=state_actions[state] 可以看做是：
#state=init()或者state=not_game(‘Win’)或者是另外的not_game(‘Gameover’)/game()

此處的意思是：state=state_actions[state] 可以看做是：state=init()或者state=not_game(‘Win’)或者是另外的not_game(‘Gameover’)/game()

結(jié)束語(yǔ)

廢話不多說(shuō)，上一個(gè)我的成功的圖，另外，可以通過(guò)設(shè)置最后幾行中的win=32來(lái)決定你最終獲勝的條件！

2048.gif

三、完整代碼

#-*- coding:utf-8 -*-
import curses
from random import randrange, choice # generate and place new tile
from collections import defaultdict
letter_codes = [ord(ch) for ch in 'WASDRQwasdrq']
actions = ['Up', 'Left', 'Down', 'Right', 'Restart', 'Exit']
actions_dict = dict(zip(letter_codes, actions * 2))
def transpose(field):
    return [list(row) for row in zip(*field)]

def invert(field):
    return [row[::-1] for row in field]

class GameField(object):
    def __init__(self, height=4, width=4, win=2048):
        self.height = height
        self.width = width
        self.win_value = win
        self.score = 0
        self.highscore = 0
        self.reset()

    def reset(self):
        if self.score > self.highscore:
            self.highscore = self.score
        self.score = 0
        self.field = [[0 for i in range(self.width)] for j in range(self.height)]
        self.spawn()
        self.spawn()

    def move(self, direction):
        def move_row_left(row):
            def tighten(row): # squeese non-zero elements together
                new_row = [i for i in row if i != 0]
                new_row += [0 for i in range(len(row) - len(new_row))]
                return new_row

            def merge(row):
                pair = False
                new_row = []
                for i in range(len(row)):
                    if pair:
                        new_row.append(2 * row[i])
                        self.score += 2 * row[i]
                        pair = False
                    else:
                        if i + 1 < len(row) and row[i] == row[i + 1]:
                            pair = True
                            new_row.append(0)
                        else:
                            new_row.append(row[i])
                assert len(new_row) == len(row)
                return new_row
            return tighten(merge(tighten(row)))

        moves = {}
        moves['Left']  = lambda field:                              \
                [move_row_left(row) for row in field]
        moves['Right'] = lambda field:                              \
                invert(moves['Left'](invert(field)))
        moves['Up']    = lambda field:                              \
                transpose(moves['Left'](transpose(field)))
        moves['Down']  = lambda field:                              \
                transpose(moves['Right'](transpose(field)))

        if direction in moves:
            if self.move_is_possible(direction):
                self.field = moves[direction](self.field)
                self.spawn()
                return True
            else:
                return False

    def is_win(self):
        return any(any(i >= self.win_value for i in row) for row in self.field)

    def is_gameover(self):
        return not any(self.move_is_possible(move) for move in actions)

    def draw(self, screen):
        help_string1 = '(W)Up (S)Down (A)Left (D)Right'
        help_string2 = '     (R)Restart (Q)Exit'
        gameover_string = '           GAME OVER'
        win_string = '          YOU WIN!'
        def cast(string):
            screen.addstr(string + '\n')

        def draw_hor_separator():
            line = '+' + ('+------' * self.width + '+')[1:]
            separator = defaultdict(lambda: line)
            if not hasattr(draw_hor_separator, "counter"):
                draw_hor_separator.counter = 0
            cast(separator[draw_hor_separator.counter])
            draw_hor_separator.counter += 1

        def draw_row(row):
            cast(''.join('|{: ^5} '.format(num) if num > 0 else '|      ' for num in row) + '|')

        screen.clear()
        cast('SCORE: ' + str(self.score))
        if 0 != self.highscore:
            cast('HGHSCORE: ' + str(self.highscore))
        for row in self.field:
            draw_hor_separator()
            draw_row(row)
        draw_hor_separator()
        if self.is_win():
            cast(win_string)
        else:
            if self.is_gameover():
                cast(gameover_string)
            else:
                cast(help_string1)
        cast(help_string2)

    def spawn(self):
        new_element = 4 if randrange(100) > 89 else 2
        (i,j) = choice([(i,j) for i in range(self.width) for j in range(self.height) if self.field[i][j] == 0])
        self.field[i][j] = new_element

    def move_is_possible(self, direction):
        def row_is_left_movable(row): 
            def change(i): # true if there'll be change in i-th tile
                if row[i] == 0 and row[i + 1] != 0: # Move
                    return True
                if row[i] != 0 and row[i + 1] == row[i]: # Merge
                    return True
                return False
            return any(change(i) for i in range(len(row) - 1))

        check = {}
        check['Left']  = lambda field:                              \
                any(row_is_left_movable(row) for row in field)

        check['Right'] = lambda field:                              \
                 check['Left'](invert(field))

        check['Up']    = lambda field:                              \
                check['Left'](transpose(field))

        check['Down']  = lambda field:                              \
                check['Right'](transpose(field))

        if direction in check:
            return check[direction](self.field)
        else:
            return False
def main(stdscr):
    def init():
        #重置游戲棋盤
        game_field.reset()
        return 'Game'
    def not_game(state):
        #畫出 GameOver 或者 Win 的界面
        game_field.draw(stdscr)
        #讀取用戶輸入得到action，判斷是重啟游戲還是結(jié)束游戲
        action = get_user_action(stdscr)
        responses = defaultdict(lambda: state) #默認(rèn)是當(dāng)前狀態(tài)，沒(méi)有行為就會(huì)一直在當(dāng)前界面循環(huán)
        responses['Restart'], responses['Exit'] = 'Init', 'Exit' #對(duì)應(yīng)不同的行為轉(zhuǎn)換到不同的狀態(tài)
        return responses[action]

    def game():
        #畫出當(dāng)前棋盤狀態(tài)
        game_field.draw(stdscr)
        #讀取用戶輸入得到action
        action = get_user_action(stdscr)

        if action == 'Restart':
            return 'Init'
        if action == 'Exit':
            return 'Exit'
        if game_field.move(action): # move successful
            if game_field.is_win():
                return 'Win'
            if game_field.is_gameover():
                return 'Gameover'
        return 'Game'


    state_actions = {
            'Init': init,
            'Win': lambda: not_game('Win'),
            'Gameover': lambda: not_game('Gameover'),
            'Game': game
        }
    curses.use_default_colors()
    game_field = GameField(win=32)
    state = 'Init'
    #狀態(tài)機(jī)開(kāi)始循環(huán)
    while state != 'Exit':
        state = state_actions[state]()
curses.wrapper(main)

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