Read word2vec binary file in Ruby

vocabulary.rb

class Vocabulary

  # @param [String] file_name Path to a word2vec vocabulary binary file
  def initialize(file_name)
    @file_name = file_name
    @size = 0
    @vocabulary = {}
    @word_count = 0
    read_file
  end

  # Supressed inspection
  #
  # Since @vocabulary can be very large, this class does not provide output of @vocabulary.
  # If you need inspection of @vocabuary, directly inspect it.
  #
  # @return [String] Supressed inspection
  def inspect
    "#<#{self.class} file_name=#{@file_name}, size=#{@size}, word_count=#{@word_count}>"
  end

  private

  def read_file
    file = File.open(@file_name)
    string_buffer = ''
    vector_buffer = []
    float_buffer = []
    mode = :word_count
    file.each_byte do |byte|
      case mode
      when :word_count, :size
        unless (?0.ord .. ?9.ord).include?(byte)
          case mode
          when :word_count
            @word_count = string_buffer.to_i
            mode = :size
          when :size
            @size = string_buffer.to_i
            mode = :vocabulary
          end
          string_buffer = ''
          next
        end

        string_buffer += byte.chr

      when :vocabulary
        if byte == 0x20
          mode = :vector
          next
        end

        string_buffer += byte.chr

      when :vector
        if vector_buffer.size == @size
          @vocabulary[string_buffer] = vector_buffer
          mode = :vocabulary
          string_buffer = ''
          vector_buffer = []
          next
        end

        float_buffer.push(byte.chr)

        if float_buffer.size == 4
          vector_buffer.push(float_buffer.join.unpack('f'))
          float_buffer = []
        end
      end
    end
  end

end