Brainfuck Interpreter

brainfuck.rb

def parseBrainFuck(string, in_while = false)                                     
  global_stack = []                                                              
  curr_index = 0                                                                 
                                                                                 
  parse_index = 0                                                                
                                                                                 
  parse_lookup = {                                                               
    "+" => lambda {global_stack[curr_index] += 1},                               
    "-" => lambda {global_stack[curr_index] -= 1},                               
    ">" => lambda {curr_index += 1},                                                
    "<" => lambda {curr_index -= 1},                                                
    "." => lambda {puts global_stack[curr_index]}                                   
  }                                                                                 
                                                                                    
  until done                                                                        
    while parse_index < string.length                                               
      if string[parse_index] == "["                                                 
        start_index = parse_index                                                   
        bracket_count = 1                                                           
        until bracket_count == 0                                                    
          if string[parse_index] == "]"                                             
            bracket_count -= 1                                                      
          elsif string[parse_index] == "["                                          
            bracket_count += 1                                                      
          end                                                                       
          parse_index += 1                                                          
        end                                                                         
        inner_string = string[start_index  + 1, parse_index - 2]                    
        parseBrainFuck(inner_string, true)                                          
      end                                                                           
                                                                                    
      if parse_lookup[string[parse_index]]                                          
        parse_lookup[string[parse_index]].call                                      
      end                                                                           
                                                                                    
      parse_index += 1                                                              
    end                                                                             
    if !in_while || global_stack[curr_index].nil?                                   
      done = true       
    else                                                                         
      parse_index = 0                                                            
    end                                                                          
  end                                                                            
end