lib/standard/hash.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2004-2008 Jean Privat <jean@pryen.org>
   4 #
   5 # This file is free software, which comes along with NIT.  This software is
   6 # distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
   7 # without  even  the implied warranty of  MERCHANTABILITY or  FITNESS FOR A
   8 # PARTICULAR PURPOSE.  You can modify it is you want,  provided this header
   9 # is kept unaltered, and a notification of the changes is added.
  10 # You  are  allowed  to  redistribute it and sell it, alone or is a part of
  11 # another product.
  12
  13 # This module is about hashable things.
  14 # It introduces an hash funtion in objects.
  15 package hash
  16
  17 import kernel
  18
  19 redef class Object
  20         # The hash code of the object.
  21         # Assuming that a = b -> a.hash = b.hash
  22         ##
  23         # Without redefinition, it is the `id' of the instance.
  24         fun hash: Int do return object_id / 8
  25 end
  26
  27 redef class Int
  28         redef fun hash do return self
  29 end
  30
  31 redef class Char
  32         redef fun hash do return ascii
  33 end
  34
  35 redef class Bool
  36         redef fun hash
  37         do
  38                 if self then
  39                         return 1
  40                 else
  41                         return 0
  42                 end
  43         end
  44 end
  45