lib/common/domain.rb

   1 require 'common/errors'
   2
   3 # A class representing a syntactically valid domain. Essentially, the
   4 # part after the "@" in an email address. Once constructed, you can be
   5 # sure that it's valid.
   6 #
   7 class Domain
   8
   9   # @domain contains the String representation of this domain.
  10   @domain = nil
  11
  12
  13   # Initialize this Domain object. If the domain is invalid, then an
  14   # {InvalidDomainError} will be raised containing the reason
  15   # why the domain is invalid.
  16   #
  17   # @param domain [String] the string representation of this domain.
  18   #
  19   def initialize(domain)
  20     if domain.empty? then
  21       msg = "domain cannot be empty"
  22       raise InvalidDomainError.new(msg)
  23     end
  24
  25     @domain = domain
  26   end
  27
  28
  29   # Convert this domain to a String.
  30   #
  31   # @return [String] the string representation of this Domain.
  32   #
  33   def to_s()
  34     return @domain
  35   end
  36
  37
  38   # Check if this Domain is equal to some other Domain. The comparison
  39   # is based on their String representations.
  40   #
  41   # @param other [Domain] the Domain object to compare me to.
  42   #
  43   # @return [Boolean] If *self* and *other* have equal String
  44   #   representations, then true is returned. Otherwise, false is
  45   #   returned.
  46   #
  47   def ==(other)
  48     return self.to_s() == other.to_s()
  49   end
  50
  51
  52   # Compare two Domain objects for sorting purposes. The comparison
  53   # is based on their String representations.
  54   #
  55   # @param other [Domain] the Domain object to compare me to.
  56   #
  57   # @return [0,1,-1] a trinary indicator of how *self* relates to *other*,
  58   #   obtained by performing the same comparison on the String
  59   #   representations of *self* and *other*.
  60   #
  61   def <=>(other)
  62     return self.to_s() <=> other.to_s()
  63   end
  64 end