life.py

#!/usr/bin/env python
# life.py -- A curses-based version of Conway's Game of Life.
# Contributed by AMK
#
# An empty board will be displayed, and the following commands are available:
# E : Erase the board
# R : Fill the board randomly
# S : Step for a single generation
# C : Update continuously until a key is struck
# Q : Quit
# Cursor keys : Move the cursor around the board
# Space or Enter : Toggle the contents of the cursor's position
#
# TODO :
# Support the mouse
# Use colour if available
# Make board updates faster
#

importrandom, string, traceback
importcurses

classLifeBoard:
"""Encapsulates a Life board

 Attributes:
 X,Y : horizontal and vertical size of the board
 state : dictionary mapping (x,y) to 0 or 1

 Methods:
 display(update_board) -- If update_board is true, compute the
 next generation. Then display the state
 of the board and refresh the screen.
 erase() -- clear the entire board
 makeRandom() -- fill the board randomly
 set(y,x) -- set the given cell to Live; doesn't refresh the screen
 toggle(y,x) -- change the given cell from live to dead, or vice
 versa, and refresh the screen display

 """
def__init__(self, scr, char=ord('*')):
"""Create a new LifeBoard instance.

 scr -- curses screen object to use for display
 char -- character used to render live cells (default: '*')
 """
self.state= {}
self.scr=scr
Y, X=self.scr.getmaxyx()
self.X, self.Y=X-2, Y-2-1
self.char=char
self.scr.clear()

# Draw a border around the board
border_line='+'+(self.X*'-')+'+'
self.scr.addstr(0, 0, border_line)
self.scr.addstr(self.Y+1,0, border_line)
foryinrange(0, self.Y):
self.scr.addstr(1+y, 0, '|')
self.scr.addstr(1+y, self.X+1, '|')
self.scr.refresh()

defset(self, y, x):
"""Set a cell to the live state"""
ifx<0orself.X<=xory<0orself.Y<=y:
raiseValueError, "Coordinates out of range %i,%i"% (y,x)
self.state[x,y] =1

deftoggle(self, y, x):
"""Toggle a cell's state between live and dead"""
ifx<0orself.X<=xory<0orself.Y<=y:
raiseValueError, "Coordinates out of range %i,%i"% (y,x)
ifself.state.has_key( (x,y) ):
delself.state[x,y]
self.scr.addch(y+1, x+1, ' ')
else:
self.state[x,y] =1
self.scr.addch(y+1, x+1, self.char)
self.scr.refresh()

deferase(self):
"""Clear the entire board and update the board display"""
self.state= {}
self.display(update_board=False)

defdisplay(self, update_board=True):
"""Display the whole board, optionally computing one generation"""
M,N=self.X, self.Y
ifnotupdate_board:
foriinrange(0, M):
forjinrange(0, N):
ifself.state.has_key( (i,j) ):
self.scr.addch(j+1, i+1, self.char)
else:
self.scr.addch(j+1, i+1, ' ')
self.scr.refresh()
return

d= {}
self.boring=1
foriinrange(0, M):
L=range( max(0, i-1), min(M, i+2) )
forjinrange(0, N):
s=0
live=self.state.has_key( (i,j) )
forkinrange( max(0, j-1), min(N, j+2) ):
forlinL:
ifself.state.has_key( (l,k) ):
s+=1
s-=live
ifs==3:
# Birth
d[i,j] =1
self.scr.addch(j+1, i+1, self.char)
ifnotlive: self.boring=0
elifs==2andlive: d[i,j] =1# Survival
eliflive:
# Death
self.scr.addch(j+1, i+1, ' ')
self.boring=0
self.state=d
self.scr.refresh()

defmakeRandom(self):
"Fill the board with a random pattern"
self.state= {}
foriinrange(0, self.X):
forjinrange(0, self.Y):
ifrandom.random() >0.5:
self.set(j,i)


deferase_menu(stdscr, menu_y):
"Clear the space where the menu resides"
stdscr.move(menu_y, 0)
stdscr.clrtoeol()
stdscr.move(menu_y+1, 0)
stdscr.clrtoeol()

defdisplay_menu(stdscr, menu_y):
"Display the menu of possible keystroke commands"
erase_menu(stdscr, menu_y)
stdscr.addstr(menu_y, 4,
'Use the cursor keys to move, and space or Enter to toggle a cell.')
stdscr.addstr(menu_y+1, 4,
'E)rase the board, R)andom fill, S)tep once or C)ontinuously, Q)uit')

defkeyloop(stdscr):
# Clear the screen and display the menu of keys
stdscr.clear()
stdscr_y, stdscr_x=stdscr.getmaxyx()
menu_y= (stdscr_y-3)-1
display_menu(stdscr, menu_y)

# Allocate a subwindow for the Life board and create the board object
subwin=stdscr.subwin(stdscr_y-3, stdscr_x, 0, 0)
board=LifeBoard(subwin, char=ord('*'))
board.display(update_board=False)

# xpos, ypos are the cursor's position
xpos, ypos=board.X//2, board.Y//2

# Main loop:
while (1):
stdscr.move(1+ypos, 1+xpos) # Move the cursor
c=stdscr.getch() # Get a keystroke
if0<c<256:
c=chr(c)
ifcin' \n':
board.toggle(ypos, xpos)
elifcin'Cc':
erase_menu(stdscr, menu_y)
stdscr.addstr(menu_y, 6, ' Hit any key to stop continuously '
'updating the screen.')
stdscr.refresh()
# Activate nodelay mode; getch() will return -1
# if no keystroke is available, instead of waiting.
stdscr.nodelay(1)
while (1):
c=stdscr.getch()
ifc!=-1:
break
stdscr.addstr(0,0, '/')
stdscr.refresh()
board.display()
stdscr.addstr(0,0, '+')
stdscr.refresh()

stdscr.nodelay(0) # Disable nodelay mode
display_menu(stdscr, menu_y)

elifcin'Ee':
board.erase()
elifcin'Qq':
break
elifcin'Rr':
board.makeRandom()
board.display(update_board=False)
elifcin'Ss':
board.display()
else: pass# Ignore incorrect keys
elifc==curses.KEY_UPandypos>0: ypos-=1
elifc==curses.KEY_DOWNandypos<board.Y-1: ypos+=1
elifc==curses.KEY_LEFTandxpos>0: xpos-=1
elifc==curses.KEY_RIGHTandxpos<board.X-1: xpos+=1
else:
# Ignore incorrect keys
pass


defmain(stdscr):
keyloop(stdscr) # Enter the main loop


if__name__=='__main__':
curses.wrapper(main)