/src/lib/abilities/hashable.e

 1-- This file is part of a Liberty Eiffel library.
 2-- See the full copyright at the end.
 3--
 4deferred class HASHABLE
 5   --
 6   -- Ancestor class for all hashable objects.
 7   --
 8   -- For example, the `hash_code' is needed for HASHED_DICTIONARY and for HASHED_SET.  Thus, most standard
 9   -- objects are HASHABLE (STRING, REAL, INTEGER_8, INTEGER_16, INTEGER_32, INTEGER_64, POINTER, NUMBER,
10   -- MUTABLE_BIG_INTEGER, and so forth).
11   --
12
13insert
14   ANY
15      redefine is_equal
16      end
17
18feature {ANY}
19   hash_code: INTEGER
20         -- The hash-code value of `Current'.
21      deferred
22      ensure
23         good_hash_value: Result >= 0
24      end
25
26   is_equal (other: like Current): BOOLEAN
27      deferred
28      ensure then
29         Result implies hash_code = other.hash_code
30      end
31
32end -- class HASHABLE
33--
34-- Copyright (C) 2009-2017: by all the people cited in the AUTHORS file.
35--
36-- Permission is hereby granted, free of charge, to any person obtaining a copy
37-- of this software and associated documentation files (the "Software"), to deal
38-- in the Software without restriction, including without limitation the rights
39-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
40-- copies of the Software, and to permit persons to whom the Software is
41-- furnished to do so, subject to the following conditions:
42--
43-- The above copyright notice and this permission notice shall be included in
44-- all copies or substantial portions of the Software.
45--
46-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
47-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
48-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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52-- THE SOFTWARE.