# Ondrej Jaura # March 2009 # www.valibuk.net

class Tape

  def initialize 
    @pos = 0
    @tape = []
  end

  def method_missing(sym, *args, &block)
    puts "# unknow #{sym} with args #{args} #{block_given? ? '' : 'and code'}"
  end

  def right
    @tape.push nil if @tape.size == @pos
    @pos += 1
  end

  def left
    if @pos == 0
      @tape.unshift nil
    else
      @pos -= 1
    end
  end

  def write(val)
    @tape[@pos] = val
  end

  def read
    @tape[@pos]
  end

  def check(val, &block)
    return unless block_given?

    while read != val do
      if block.arity == 1
        yield read
      else
        yield
      end
    end
  end

  def condition(val, positive, negative)
    if read == val
      positive.call
    else
      negative.call
    end
  end

  def dump
    t = @tape.map {|c| " #{c} "}
    t[@pos] = "|#{@tape[@pos]}|"
    puts "[#{t.join(',')}]"
  end

  def comment(text)
    puts text
  end

  def self.load(filename)
    new.instance_eval(File.read(filename), filename)
  end
end

Tape.load(ARGV.shift)