/src/lib/iterator/bidirectional_iterator.e

 1-- This file is part of a Liberty Eiffel library.
 2-- See the full copyright at the end.
 3--
 4deferred class BIDIRECTIONAL_ITERATOR[E_]
 5   -- An iterator that allows to traverse a COLLECTION forward and backward.
 6
 7   -- Those COLLECTIONs can be iterated back and forth even if its items are
 8   -- not COMPARABLE. For example a two-way list of three-dimensional points
 9   -- may while the points are not naturally ordered.
10
11inherit
12   ITERATOR[E_]
13
14feature {ANY}
15   finish
16         -- Positions the iterator to the last object in the
17         -- aggregate to be traversed.
18      deferred
19      ensure
20         is_valid
21      end
22
23   previous
24         -- Positions the iterator to the previous object in the
25         -- sequence.
26      require
27         is_valid
28         not is_off
29      deferred
30      end
31
32end -- class BIDIRECTIONAL_ITERATOR
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
49-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
50-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
51-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
52-- THE SOFTWARE.