class Brainfuck
    def self.run(src)
        b = check_bracket(src)
        pc = 0
        p = 0
        t = Array.new(30000, 0)
        while pc < src.size
            case src[pc]
            when ?> then p += 1
            when ?< then p -= 1
            when ?+ then t[p] = (t[p] + 1) % 256
            when ?- then t[p] = (t[p] - 1) % 256
            when ?. then print t[p].chr
            when ?, then t[p] = $stdin.getc.to_i
            when ?[ then pc = b[pc] if t[p].zero?
            when ?] then pc = b.invert[pc] - 1
            end
        pc += 1
        end
    end

    private
    def self.check_bracket(src)
        s = []
        l = []
        src.each_byte.with_index do |b, i|
            case b.chr
            when '['
                s << i
            when ']'
                l << [s.pop, i]
            end
        end
    return Hash[*l.flatten]
    end
end