/src/lib/backtracking/low_level/abstract_backtracking_cut_point.e

 1-- This file is part of a Liberty Eiffel library.
 2-- See the full copyright at the end.
 3--
 4class ABSTRACT_BACKTRACKING_CUT_POINT
 5   --
 6   -- Instances of that class are used by the ABSTRACT_BACKTRACKING
 7   -- to record "cut points" data. A cut point is an indication of
 8   -- up to which alternative are to be removed from the exploration.
 9   --
10   -- Instances of that class are inserted in the continuation path
11   -- to be retrieved by dynamic cast during calls to cut.
12   --
13
14inherit
15   ABSTRACT_BACKTRACKING_SEQUENCE
16      rename pool as pool_of_cut_points
17      end
18
19insert
20   ABSTRACT_BACKTRACKING_GLOBALS
21
22feature {ABSTRACT_BACKTRACKING}
23   top_alternative: ABSTRACT_BACKTRACKING_ALTERNATIVE
24         -- Record of what top of the stack of alternative
25         -- is to restore when cut is called.
26         -- Managed by ABSTRACT_BACKTRACKING.
27
28   set_top_alternative (value: like top_alternative)
29      do
30         top_alternative := value
31      ensure
32         definition: top_alternative = value
33      end
34
35   next_sequence (explorer: ABSTRACT_BACKTRACKING)
36         -- Do nothing: remove itself (as if it were the end
37         -- of a sequence) and evaluate the continuation by
38         -- issuing a 'continue'.
39      do
40         explorer.pop_sequence
41         explorer.continue
42      end
43
44end -- class ABSTRACT_BACKTRACKING_CUT_POINT
45--
46-- Copyright (C) 2009-2017: by all the people cited in the AUTHORS file.
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54--
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