def __init__(self): self.board = Board() self.cur_turn = 'p1' self.gameover = False self.winner = 'n/a' self.pc_first = True # game engine goes first self.algo = alpha_beta_root # assigning function pointer self.ui = Terminal(self.board) # game UI is command line terminal! self.nom = 2 # number of moves done on board
class Game(object):
'''Class Game
This class implements the game engine for game Isolation.
'''
def __init__(self):
self.board = Board()
self.cur_turn = 'p1'
self.gameover = False
self.winner = 'n/a'
self.pc_first = True # game engine goes first
self.algo = alpha_beta_root # assigning function pointer
self.ui = Terminal(self.board) # game UI is command line terminal!
self.nom = 2 # number of moves done on board
def __get_direction(self, pos, move):
'''Find the direction of move relative to pos.
Return 'N', 'NE', 'E', 'SE', 'S', 'SW', 'W' or 'NW'.
'''
if move[1]==pos[1] and move[0]<pos[0]: return 'N'
if move[1]==pos[1] and move[0]>pos[0]: return 'S'
if move[0]==pos[0] and move[1]<pos[1]: return 'W'
if move[0]==pos[0] and move[1]>pos[1]: return 'E'
if move[1]>pos[1] and (move[1]-pos[1])==(move[0]-pos[0]): return 'SE'
if move[1]<pos[1] and (move[1]-pos[1])==(move[0]-pos[0]): return 'NW'
if move[1]>pos[1] and (move[1]-pos[1])==(pos[0]-move[0]): return 'NE'
if move[1]<pos[1] and (move[1]-pos[1])==(pos[0]-move[0]): return 'SW'
# move is not in any of the 8 directions:
return None
def __is_blocked(self, drt, pos, move):
'''Check if move is blocked by visited positions on board.
--- Function Arguments ---
@drt: direction the move is in.
@pos: the original position the pawn was at.
@move: the move the pawn at pos try to make.
@return: True if blocked, otherwise False.
'''
board = self.board.get_board()
if drt == 'N':
for i in xrange(1, pos[0]-move[0]):
if board[pos[0]-i][pos[1]]: return True
elif drt == 'S':
for i in xrange(1, move[0]-pos[0]):
if board[pos[0]+i][pos[1]]: return True
elif drt == 'E':
for i in xrange(1, move[1]-pos[1]):
if board[pos[0]][pos[1]+i]: return True
elif drt == 'W':
for i in xrange(1, pos[1]-move[1]):
if board[pos[0]][pos[1]-i]: return True
elif drt == 'NE':
for i in xrange(1, move[1]-pos[1]):
if board[pos[0]-i][pos[1]+i]: return True
elif drt == 'NW':
for i in xrange(1, pos[1]-move[1]):
if board[pos[0]-i][pos[1]-i]: return True
elif drt == 'SE':
for i in xrange(1, move[1]-pos[1]):
if board[pos[0]+i][pos[1]+i]: return True
else: # SW
for i in xrange(1, pos[1]-move[1]):
if board[pos[0]+i][pos[1]-i]: return True
return False
def __set_gameover(self):
"A helper function to set gameover and winner flag."
self.gameover = True
self.winner = 'p1' if self.cur_turn=='p2' else'p2'
def __set_search_depth(self):
"A helper function to set search depth for alpha-beta algorithm."
if self.nom <= 15: return 6
elif self.nom <= 25: return 8
elif self.nom <= 35: return 10
elif self.nom <= 45: return 12
elif self.nom <= 55: return 14
else: return 10
def is_valid_move(self, move):
'''Check if move is valid.
Assume the format of move is sanitized by UI interface.
--- Function Arguments ---
@move: the move player in the current turn makes.
@return: False if not a valid move, otherwise True.
'''
# check entry validity
if not move[0] in xrange(self.board.size+1): return False
if not move[1] in xrange(self.board.size+1): return False
# check if move already exists on board!
board = self.board.get_board()
if board[move[0]][move[1]]: return False
# check if move direction is correct
pos = self.board.get_position(self.cur_turn)
drt = self.__get_direction(pos, move)
if not drt: return False
# check if move is blocked by visited moves on the path
if self.__is_blocked(drt, pos, move): return False
return True
def make_move(self, move):
"Make the move for the player in the current turn. Assume move is sanitized and checked."
self.board.set_move(move, self.cur_turn)
self.cur_turn = 'p1' if self.cur_turn=='p2' else 'p1'
self.nom += 1
def ai_goes(self):
"Game AI makes his move."
# determine the depth for alpha-beta algorithm to search first
depth = self.__set_search_depth()
# find best move that can be searched so far
move = self.algo(self.cur_turn, self.board, depth, NEG_INFINITY, POS_INFINITY)
# best move can be 'not found' when AI knows it loses
# in that case a 'None' type is returned!
if move: self.make_move(move)
else: self.__set_gameover()
def human_goes(self):
"Human player make his/her move."
self.cur_turn = 'p2'
while True:
move = self.ui.prompt_user_input()
if self.ui.is_surrender_move(move):
self.__set_gameover()
break
elif self.is_valid_move(move):
self.make_move(move)
break
else:
print 'Illegitimate move!'
def reset_game(self):
"Reset all game states when game is over."
self.board.clear_board()
self.cur_turn = 'p1'
self.gameover = False
self.winner = 'n/a'
self.pc_first = True # game engine goes first
self.nom = 2 # number of moves done on board
