Parser example: from lines in a file to a structured array

parser.rb

class Parser

  # Gets ready to parse the input file
  def initialize(filename)
    generate_command_array(filename) # 
    @index = 0
  end

  # ...
  
  private
  
    # Place each line into a nested array. For example, push constant 3 becomes
    # ['push', 'constant', '3'] and add becomes ['add']. The entire instructions
    # array becomes nested [ ['push', 'constant', '3'], ['push', 'constant', '5'], ['add']]
    def generate_command_array(filename)
      begin
        raise TranslatorException.new("Could not read #{filename}.") unless File.readable?(filename)
        # Read each line in the file and remove comments and all extra whitespace
        vmfile = File.open(filename, 'r') do |f|
          @instructions = f.readlines
          @instructions.each {|i| i.gsub! /\/\/.*/, ''; i.strip!; i.squeeze!(' ')}
          @instructions.delete('')
        end
      rescue => e  
        abort(e.message)
      end
      # Take each instruction string and split them into a 2d array
      @instructions.each_with_index do |cmd, i|
        cmd_array = cmd.split
        @instructions[i] = cmd_array
      end
    end

end