Tetris (Python recipe) by Alfe

ActiveState Code (http://code.activestate.com/recipes/580680/)

#!/usr/bin/env python
"tetris -- a brand new game written in python by Alfe"

import sys, random, time, select, os, termios

width = 10
height = 22

blocks = [ [ (0,0), (0,1),  (0,-1),  (1,0)  ],  # T
           [ (0,0), (0,1),  (0,2),   (0,-1) ],  # I
           [ (0,0), (0,1),  (1,1),  (-1,0)  ],  # S
           [ (0,0), (0,-1), (1,-1), (-1,0)  ],  # Z
           [ (0,0), (0,1),  (1,1),   (1,0)  ],  # O
           [ (0,0), (-1,1), (-1,0),  (1,0)  ],  # L
           [ (0,0), (1,1),  (-1,0),  (1,0)  ],  # J
           ]

inverted     = '\033[7;1m'
blue         = '\033[7;34m'
normal       = '\033[0m'
clear_screen = '\033[2J'  # clear the screen
home         = '\033[H'   # goto top left corner of the screen
# (the latter two were found using 'clear | od -c')

empty = '  '
black = inverted + '  ' + normal  # two inverted spaces
blue  = blue     + '  ' + normal  # two inverted spaces
floor = '=='

left  = 'left'
right = 'right'
turn  = 'turn'
down  = 'down'
quit  = 'quit'

shaft = None

def play_tetris():  
    initialize_shaft()
    while True:  # until game is lost
        block = get_random_block()
        coordinates = (width/2-1, 1)  # in the middle at the top
        if not place_block(block, coordinates, blue):  # collision already?
            return  # game is lost!
        next_fall_time = time.time() + fall_delay()
        # ^^^ this is the time when the block will fall automatically
        #     one line down
        while True:  # until block is placed fixedly
            print_shaft()
            remove_block(block, coordinates)
            x, y = coordinates
            try:
                try:
                    command = get_command(next_fall_time)
                except Timeout:  # no command given
                    raise Fall()
                else:  # no exception, so process command:
                    if   command == left:
                        new_coordinates = (x-1, y)
                        new_block = block
                    elif command == right:
                        new_coordinates = (x+1, y)
                        new_block = block
                    elif command == turn:
                        new_coordinates = (x, y)
                        new_block = turn_block(block)
                    elif command == down:
                        raise Fall()
                    elif command == quit:
                        return
                    else:
                        raise Exception("internal error: %r" % command)
                    if place_block(new_block, new_coordinates,
                                   blue):  # command ok?
                        # execute the command:
                        block       = new_block
                        coordinates = new_coordinates
                    else:
                        place_block(block, coordinates, blue)
                        # ignore the command which could not be executed
                        # maybe beep here or something ;->
            except Fall:  
                # make the block fall automatically:
                new_coordinates = (x, y+1)
                next_fall_time = time.time() + fall_delay()
                if place_block(block, new_coordinates, blue):  # can be placed?
                    coordinates = new_coordinates
                else:
                    place_block(block, coordinates,
                                black)  # place block there again
                    break               # and bail out
        remove_full_lines()

class Timeout(Exception):  pass
class    Fall(Exception):  pass

def remove_full_lines():               
    global shaft, width, height
    def line_full(line):  
        global width
        for x in range(width):
            if line[x] == empty:
                return False
        return True
    
    def remove_line(y):   
        global shaft, width
        del shaft[y]  # cut out line
        shaft.insert(0, [ empty ] * width)  # fill up with an empty line
    
    for y in range(height):  
        if line_full(shaft[y]):
            remove_line(y)

def fall_delay():                      
    return 1.3  # cheap version; implement raising difficulty here

def turn_block(block):                 
    "return a turned copy(!) of the given block"
    result = []
    for x, y in block:
        result.append((y, -x))
    return result

def get_command(next_fall_time):       
    "if a command is entered, return it; otherwise raise the exception Timeout"
    while True:  # until a timeout occurs or a command is found:
        timeout = next_fall_time - time.time()
        if timeout > 0.0:
            (r, w, e) = select.select([ sys.stdin ], [], [], timeout)
        else:
            raise Timeout()
        if sys.stdin not in r:  # not input on stdin?
            raise Timeout()
        key = os.read(sys.stdin.fileno(), 1)
        if   key == 'j':
            return left
        elif key == 'l':
            return right
        elif key == 'k':
            return turn
        elif key == ' ':
            return down
        elif key == 'q':
            return quit
        else:  # any other key:  ignore
            pass

def place_block(block, coordinates, color):  
    "if the given block can be placed in the shaft at the given coordinates"\
    " then place it there and return True; return False otherwise and do not"\
    " place anything"
    global shaft, width, height
    block_x, block_y = coordinates
    for stone_x, stone_y in block:
        x = block_x + stone_x
        y = block_y + stone_y
        if (x < 0 or x >= width or
            y < 0 or y >= height or  # border collision?
            shaft[y][x] != empty):   # block collision?
            return False  # cannot be placed there
    # reached here?  ==> can be placed there
    # now really place it:
    for stone_x, stone_y in block:
        x = block_x + stone_x
        y = block_y + stone_y
        shaft[y][x] = color
    return True

def remove_block(block, coordinates):  
    global shaft
    block_x, block_y = coordinates
    for stone_x, stone_y in block:
        x = block_x + stone_x
        y = block_y + stone_y
        shaft[y][x] = empty

def get_random_block():                
    if random.randint(1, 10) == 1:
        return perfect_block() or random.choice(blocks)
    return random.choice(blocks)

def perfect_block():
    result = []
    for y in range(height):
        if filter(lambda b: b != empty, shaft[y]):  # found summit
            random_order = range(width)
            random.shuffle(random_order)
            for x in random_order:
                if shaft[y][x] == empty:  # found space besides summit
                    for x_ in range(width-x):  # fill to the right
                        if shaft[y][x+x_] != empty:
                            break
                        for y_ in range(height-y):
                            if shaft[y+y_][x+x_] == empty:
                                result.append((x_, y_))
                            else:
                                break
                    for x_ in range(-1, -x-1, -1):  # fill to the left
                        if shaft[y][x+x_] != empty:
                            break
                        for y_ in range(height-y):
                            if shaft[y+y_][x+x_] == empty:
                                result.append((x_, y_))
                            else:
                                break
                    # shift block in x direction to center it:
                    xmin = min(map(lambda v: v[0], result))
                    xmax = max(map(lambda v: v[0], result))
                    return map(lambda v: (v[0]-(xmax+xmin)/2, v[1]), result)
    return None

def initialize_shaft():                
    global width, height, shaft, empty
    shaft = [ None ] * height
    for y in range(height):
        shaft[y] = [ empty ] * width

def print_shaft():                     
    # cursor-goto top left corner:
    sys.stdout.write(home)
    for y in range(height):  
        if y > 3:  # does this line have a border?  (the topmost ones do not)
            sys.stdout.write(']')
        else:
            sys.stdout.write(' ')
        for x in range(width):
            sys.stdout.write(shaft[y][x])
        if y > 3:  # does this line have a border?  (the topmost ones do not)
            sys.stdout.write('[\n')
        else:
            sys.stdout.write('\n')
    
    # print bottom:
    sys.stdout.write(']' + floor * width + '[\n')

def prepare_tty():                       
    "set the terminal in char mode (return each keyboard press at once) and"\
    " switch off echoing of this input; return the original settings"
    stdin_fd = sys.stdin.fileno()  # will most likely be 0  ;->
    old_stdin_config = termios.tcgetattr(stdin_fd)
    [ iflag, oflag, cflag, lflag, ispeed, ospeed, cc ] = \
        termios.tcgetattr(stdin_fd)
    cc[termios.VTIME] = 1
    cc[termios.VMIN] = 1
    iflag = iflag & ~(termios.IGNBRK |
                      termios.BRKINT |
                      termios.PARMRK |
                      termios.ISTRIP |
                      termios.INLCR |
                      termios.IGNCR |
                      #termios.ICRNL |
                      termios.IXON)
    #  oflag = oflag & ~termios.OPOST
    cflag = cflag | termios.CS8
    lflag = lflag & ~(termios.ECHO |
                      termios.ECHONL |
                      termios.ICANON |
                      # termios.ISIG |
                      termios.IEXTEN)
    termios.tcsetattr(stdin_fd, termios.TCSANOW,
                      [ iflag, oflag, cflag, lflag, ispeed, ospeed, cc ])
    return (stdin_fd, old_stdin_config)

def cleanup_tty(original_tty_settings):  
    "restore the original terminal settings"
    stdin_fd, old_stdin_config = original_tty_settings
    termios.tcsetattr(stdin_fd, termios.TCSADRAIN, old_stdin_config)

original_tty_settings = prepare_tty()  # switch off line buffering etc.
sys.stdout.write(clear_screen)
try:  # ensure that tty will be reset in the end
    play_tetris()
finally:
    cleanup_tty(original_tty_settings)