A tiny, self-sustained implementation of Sokoban

sokoban.rb

require 'io/console'

# minimal Sokoban implementation
# by knarka
# released into the public domain
class Sokoban
	def initialize
		@levels = DATA.readlines.map { |r| Level.new r }
		main
	end

	private

	def main
		loop do
			win if @level.nil? && @levels.empty?
			@level = @levels.shift if @level.nil?

			@level.draw

			@level.handle STDIN.getch

			@level = nil if @level.done?
		end
	end

	def win
		puts 'you win!'
		exit
	end

	class Level
		def initialize(raw)
			i = -1
			@map = raw.split('-').map do |l|
				i += 1
				width ||= l.length
				raise 'uneven level' unless l.length == width

				l.chars.map do |c|
					@pos = [i, l.index('@')] if ['@', '+'].include?(c) && @pos.nil?
					c
				end
			end
		end

		def done?
			@map.each { |l| l.each { |c| return false if c == 'o' } }
			true
		end

		def draw
			@map.each { |l| puts l.join }
			puts
		end

		def handle(key)
			case key
			when 'j' then move 0, :+
			when 'k' then move 0, :-
			when 'l' then move 1, :+
			when 'h' then move 1, :-
			when 'q' then abort 'you lose'
			end
		end

		private

		def move(index, operator)
			dpos = @pos.clone
			dpos[index] = dpos[index].public_send(operator, 1)

			case get_field(dpos)
			when '.', ' '
				move_player @pos, dpos
				@pos = dpos
			when 'o'
				dcube = @pos.clone
				dcube[index] = dcube[index].public_send(operator, 2)

				if ['.', ' '].include? get_field(dcube)
					move_cube dpos, dcube
					move_player @pos, dpos
					@pos = dpos
				end
			end
		end

		def get_field(pos)
			@map[pos[0]][pos[1]]
		end

		def set_field(pos, value)
			@map[pos[0]][pos[1]] = value
		end

		def move_player(old, new)
			set_field(old, get_field(old) == '@' ? ' ' : '.')
			set_field(new, get_field(new) == ' ' ? '@' : '+')
		end

		def move_cube(old, new)
			set_field(old, ' ')
			set_field(new, get_field(new) == '.' ? '*' : 'o')
		end
	end
end

Sokoban.new

__END__
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