better filter parser

  def eval_filter(arg)

    arg.gsub!("\\'", "\x7") # FIXPAUL: hack! ;)

    if m = arg.match(/^([a-zA-Z_-]+) *= *'(.*)'$/)

      @filters << [m[1], :equals, m[2]]

    elsif m = arg.match(/^([a-zA-Z_-]+) *= *([0-9]+)$/)

      @filters << [m[1], :equals, m[2].to_i]

    elsif m = arg.match(/^([a-zA-Z_-]+) *= *([0-9]+\.[0-9]+)$/)

      @filters << [m[1], :equals, m[2].to_f]

    elsif m = arg.match(/^([a-zA-Z_-]+) *< *([0-9]+)$/)

      @filters << [m[1], :less_than, m[2].to_i]

    elsif m = arg.match(/^([a-zA-Z_-]+) *< *([0-9]+\.[0-9]+)$/)

      @filters << [m[1], :less_than, m[2].to_f]

    elsif m = arg.match(/^([a-zA-Z_-]+) *> *([0-9]+)$/)

      @filters << [m[1], :greater_than, m[2].to_i]

    elsif m = arg.match(/^([a-zA-Z_-]+) *> *([0-9]+\.[0-9]+)$/)

      @filters << [m[1], :greater_than, m[2].to_f]

    elsif m = arg.match(/^([a-zA-Z_-]+) *~ *([0-9]+)-([0-9]+)$/)

      @filters << [m[1], :range_include, (m[2].to_i..m[3].to_i)]

    elsif m = arg.match(/^([a-zA-Z_-]+) *~ *([0-9]+\.[0-9]+)-([0-9]+\.[0-9]+)$/)

      @filters << [m[1], :range_include, (m[2].to_f..m[3].to_f)]

    elsif m = arg.match(/^([a-zA-Z_-]+) *& *(([0-9]+),)+([0-9]+)$/)

      @filters << [m[1], :list_include, m[2..-1].map(&:to_i)]

    elsif m = arg.match(/^([a-zA-Z_-]+) *& *(([0-9]+\.[0-9]+),)+([0-9]+\.[0-9]+)$/)

      @filters << [m[1], :list_include, m[2..-1].map(&:to_f)]

    elsif m = arg.match(/^([a-zA-Z_-]+) *& *('[^']*',)+'[^']*'$/)

      lst = arg.match(/^([a-zA-Z_-]+) *& *(.*)/)[2].scan(/'([^']*)',?/).map do |x|

    key_regex = "([^ ]+)"

    if m = arg.match(/^#{key_regex} *= *'([^']*)'$/)

      @filters << [m[1].gsub("\x7", "'"), :equals, m[2]]

    elsif m = arg.match(/^#{key_regex} *= *([0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :equals, m[2].to_i]

    elsif m = arg.match(/^#{key_regex} *= *([0-9]+\.[0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :equals, m[2].to_f]

    elsif m = arg.match(/^#{key_regex} *< *([0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :less_than, m[2].to_i]

    elsif m = arg.match(/^#{key_regex} *< *([0-9]+\.[0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :less_than, m[2].to_f]

    elsif m = arg.match(/^#{key_regex} *> *([0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :greater_than, m[2].to_i]

    elsif m = arg.match(/^#{key_regex} *> *([0-9]+\.[0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :greater_than, m[2].to_f]

    elsif m = arg.match(/^#{key_regex} *~ *([0-9]+)-([0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :range_include, (m[2].to_i..m[3].to_i)]

    elsif m = arg.match(/^#{key_regex} *~ *([0-9]+\.[0-9]+)-([0-9]+\.[0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :range_include, (m[2].to_f..m[3].to_f)]

    elsif m = arg.match(/^#{key_regex} *& *(([0-9]+),)+([0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :list_include, m[2..-1].map(&:to_i)]

    elsif m = arg.match(/^#{key_regex} *& *(([0-9]+\.[0-9]+),)+([0-9]+\.[0-9]+)$/)

      @filters << [m[1].gsub("\x7", "'"), :list_include, m[2..-1].map(&:to_f)]

    elsif m = arg.match(/^#{key_regex} *& *('[^']*',)+'[^']*'$/)

      @filters << [m[1].gsub("\x7", "'"), :list_include, arg

        .match(/^#{key_regex} *& *(.*)/)[2].scan(/'([^']*)',?/).map do |x|

          x.first.gsub("\x7", "'")

      end

      @filters << [m[1], :list_include, lst.to_a]

    elsif m = arg.match(/^([a-zA-Z_-]+)$/)

      @filters << [m[1], :exists, nil]

      end.to_a]

    elsif m = arg.match(/^#{key_regex}$/)

      @filters << [m[1].gsub("\x7", "'"), :exists, nil]

    else

      raise InvalidQueryError.new("invalid filter: filter(#{arg})")

    end