Befunge interpreter in CoffeeScript

befunge.coffee

interpret = (code) ->
	commands = 
		'+' : =>
			@stack.push(@stack.pop() + @stack.pop())
			
		'-' : =>
			@stack.push(-@stack.pop() + @stack.pop())
			
		'*' : =>
			@stack.push(@stack.pop() * @stack.pop())
			
		'/' : =>
			a = @stack.pop()
			b = @stack.pop()
			if a == 0
				@stack.push(0)
			else
				@stack.push(Math.floor(b/a))
				
		'%' : =>
			a = @stack.pop()
			b = @stack.pop()
			if a == 0
				@stack.push(a)
			else
				@stack.push(b%a)
				
		'!' : =>
			@stack.push(if @stack.pop() == 0 then 1 else 0)
			
		'`' : =>
			@stack.push(if @stack.pop() < @stack.pop() then 1 else 0)
			
		'>' : => @direction = '>'
			
		'<' : => @direction = '<'
		
		'^' : => @direction = '^'
		
		'v' : => @direction = 'v'
		
		'?' : => @direction = '><^v'[Math.floor(Math.random()*4)]
		
		'_' : =>
			@direction = (if @stack.pop() == 0 then '>' else '<')
			
		'|' : =>
			@direction = (if @stack.pop() == 0 then 'v' else '^')
			
		'"' : =>
			@strMode = !@strMode
		
		':' : =>
			a = @stack.pop()
			if a is undefined
				@stack.push(0)
			else
				@stack.push(a)
				@stack.push(a)
				
		'\\' : =>
			a = @stack.pop()
			b = @stack.pop() or 0
			@stack.push(b)
			@stack.push(a)
			
		'$' : =>
			@stack.pop()
			
		'.' : =>
			@output += @stack.pop().toString()

		',' : =>
			@output += String.fromCharCode(@stack.pop())

		'p' : =>
			y = @stack.pop()
			x = @stack.pop()
			v = @stack.pop()
			@codeMap[y][x] = String.fromCharCode(v)

		'g' : =>
			y = @stack.pop()
			x = @stack.pop()
			@stack.push(@codeMap[y][x].charCodeAt(0))

	for i in [0..9]
		commands[i] = do (i) => => @stack.push(i)
	
	mright = =>
		@x += 1
		if @x >= @width
			@x = 0
	mleft = =>
		@x -= 1
		if @x < 0
			@x = @width - 1
	mup = =>
		@y -= 1
		if @y < 0
			@y = @height - 1
	mdown = =>
		@y += 1
		if @y >= @height
			@y = 0

	move = =>
		{
			'>' : mright
			'<' : mleft
			'^' : mup
			'v' : mdown
		}[@direction]()

	@direction = '>'
	@codeMap = code.split('\n').map (c) -> c.split('')
	@width = 80
	@height = 25
	@stack = []
	@output = ''
	@x = 0
	@y = 0
	@strMode = false

	while true
		cmd = @codeMap[@y][@x]
		if @strMode and cmd isnt '"'
			@stack.push(cmd.charCodeAt(0))
			move()
		else
			switch cmd
				when '@'
					return @output
				when ' '
					move()
				when '#'
					move()
					move()
				else
					commands[cmd]()
					move()

test.bef

2>:3g" "-!v\  g30          <
 |!`"O":+1_:.:03p>03g+:"O"`|
 @               ^  p3\" ":<
2 234567890123456789012345678901234567890123456789012345678901234567890123456789