checkers

checkers.py

from itertools import product
from pprint import pprint

class Board(object):
    def __init__(self):
        self.board = {(a,b):None for a,b in product(range(10),repeat = 2)}
        
        self.place_black()
        self.place_white()
    
    def place_black(self):
        for row in range(4):
            for spot in self.spots(row):
                self.board[spot] = Piece('black')

    def place_white(self):
        for row in range(6, 10):
            for spot in self.spots(row):
                self.board[spot] = Piece('white')

    def spots(self, row):
        '''yields valid spots on a row'''

        start = not(row % 2)

        for i in range(start, 10, 2):
            yield (i,row)

    def row(self, key):
        '''yields pieces on a particular row'''
        for i in range(10):
            yield self.board[(i, key)]

    def __str__(self):
        result = ''
        for row in range(10):
            line = '{}\n'.format(''.join(
                str(c) if c else '.' for c in self.row(row)
                        ))
            result += line
        return result

    @staticmethod
    def tupple_add(a,b):
        return (a[0]+b[0], a[1]+b[1])

    def generate_valid_moves(self, start):
        piece = self.board[start]
        if piece is None:
            raise IndexError('No piece at {}'.format(start))

        result = []
        for move in piece.possible_moves:
            stop = self.tupple_add(start, move)
            if stop not in self.board:
                continue
            if self.board[stop] is not None:
                continue
            result.append(stop)

        return result

    def move(self, start, stop):
        '''move piece at start to stop'''
        moves = self.generate_valid_moves(start)

        piece = self.board[start]
        if stop not in moves:
            raise IndexError('Cannot move {} to {}'.format(
                start, stop))

        self.board[start] = None
        self.board[stop] = piece

class Piece(object):
    def __init__(self, color):
        self.color = color.lower()

    def __str__(self):
        return self.color[0].upper()

    @property
    def possible_moves(self):
        '''return a list of valid moves'''
        if self.color == 'black':
            direction = 1
        else: 
            direction = -1

        return [(-1, direction), (1,direction)]

    def king(self):
        '''king a piece'''
        return King(self.color)

class King(Piece):
    @property
    def possible_moves(self):
        return [(-1,-1), (1,-1), (-1,1), (1,1)]


b = Board()
print(b)
b.move( (0,3), (1,4))
print(b)