brainfuck.rb

#
# (c) 2008 you_katan
#

class Brainfuck
  SIZE = 100
	
  def initialize(src, data = '')
    @src = src
    @table = Array.new(SIZE, 0)
    @data = data
    @cur = 0
    @ptr = 0
  end
	
  def parse
    0.upto @src.length do |i|
      ch = @src.slice i, 1
      case ch
      when '+'
        @table[@cur] += 1
        
      when '-'
        @table[@cur] -= 1
        
      when '.'
        print @table[@cur].chr
        
      when ','
        @data.slice(@ptr, 1).each_byte {|ch|
          @table[@cur] = ch
        }
        @ptr += 1
        
      when '>'
        @cur += 1
        @cur = 0 if cur > SIZE
        
      when '<'
        @cur -= 1
        @cur = SIZE if cur < 0
        
      when '['
        if (@table[@cur] == 0)
          opened = 0
          i.upto @src.length do |k|
            ch = @src.slice k, 1
            if ch == '['
              opened += 1
            elsif ch == ']'
              opened -= 1
              break if opened == 0
            end
          end
        end
        i = k
        
      when ']'
        if (@table[@cur] != 0)
          closed = 0
          i.downto 0 do |k|
            ch = @src.slice k, 1
            if ch == ']'
              closed += 1
            elsif ch == '['
              closed -= 1
              break if closed == 0
            end
          end
          i = k
        end
        
      end
    end
  end
end

if $0 == File.basename(__FILE__)
  bf = Brainfuck.new('++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.+++++++++++++++++++++++++++++.+++++++..+++.-------------------------------------------------------------------------------.+++++++++++++++++++++++++++++++++++++++++++++++++++++++.++++++++++++++++++++++++.+++.------.--------.-------------------------------------------------------------------.-----------------------.')
  bf.parse
end