root/lang/ruby/misc/brainfuck.rb @ 466

#!/usr/bin/env ruby
=begin
A Brainfuck Interpreter

Public Domain
=end

arr = []
ptr = 0

soc = ARGF.read
pos = 0

while soc.size > pos
        print soc[pos].chr if $DEBUG
        p arr if $DEBUG
        
        arr[ptr] ||= 0
        
        case soc[pos]
        when ?>
                ptr += 1
        when ?<
                ptr -= 1
        when ?+
                arr[ptr] += 1 
        when ?-
                arr[ptr] -= 1
        when ?.
                print arr[ptr].chr
        when ?,
                arr[ptr] = $stdin.getc
        when ?[
                if arr[ptr].zero?
                        n = 1
                        while n.nonzero?
                                pos += 1
                                case soc[pos]
                                when ?[
                                        n += 1
                                when ?]
                                        n -= 1
                                end
                        end
                end
        when ?]
                n = -1
                while n.nonzero?
                        pos -= 1
                        case soc[pos]
                        when ?[
                                n += 1
                        when ?]
                                n -= 1
                        end
                end
                pos -= 1
        when ??
                puts arr.inspect + " ptr=#{ptr}"
        end
        pos += 1
end
puts