166 lines
3.0 KiB
Prolog
166 lines
3.0 KiB
Prolog
% This file has been included as an YAP library by Vitor Santos Costa, 2013
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% it implements a very simple interval solver designed to interact with the exo
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% data-base.
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% It assumes simple queries and a contiguous interval,
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% and does not really expect to do non-trivial
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% constraint propagation and solving.
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:- module(exo_interval,
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[max/2,
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min/2,
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any/2,
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max/1,
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min/1,
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maximum/1,
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minimum/1,
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any/1,
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(#<)/2,
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(#>)/2,
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(#=<)/2,
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(#>=)/2,
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(#=)/2,
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op(700, xfx, (#>)),
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op(700, xfx, (#<)),
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op(700, xfx, (#>=)),
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op(700, xfx, (#=<)),
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op(700, xfx, (#=))]).
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:- meta_predicate max(?,0), min(?,0), any(?,0).
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max(X, G) :-
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insert_atts(X, i(_,_,max)),
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call(G).
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min(X, G) :-
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insert_atts(X, i(_,_,min)),
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call(G).
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max(X) :-
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insert_atts(X, i(_,_,max)).
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maximum(X) :-
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insert_atts(X, i(_,_,maximum)).
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any(X) :-
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insert_atts(X, i(_,_,any)).
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min(X) :-
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insert_atts(X, i(_,_,min)).
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minimum(X) :-
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insert_atts(X, i(_,_,minimum)).
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least(X) :-
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insert_atts(X, i(_,_,least)).
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X #> Y :-
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( var(X) -> insert_atts(X, i(Y,_,_))
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;
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( var(Y) -> insert_atts(Y, i(_,X,_) ) ;
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true
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)
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;
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var(Y) -> insert_atts(Y, i(_,X,_))
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;
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X > Y
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).
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X #>= Y :-
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( var(X) -> insert_atts(X, i(Y-1,_,_))
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;
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X >= Y
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).
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X #< Y :-
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( var(X) -> insert_atts(X, i(_,Y,_))
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;
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X < Y
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).
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X #=< Y :-
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( var(X) -> insert_atts(X, i(Y+1,_,_))
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;
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X =< Y
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).
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X #= Y :-
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( var(X) -> insert_atts(X, i(Y-1,Y+1,_)) ;
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X =:= Y
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).
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attribute_goals(X) -->
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{ get_attr(X, exo_interval, Op) },
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( { Op = max } -> [max(X)] ;
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{ Op = min } -> [min(X)] ;
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{ Op = '>'(Y) } -> [X #> Y] ;
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{ Op = '<'(Y) } -> [X #< Y] ;
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{ Op = range(A,B,C) } ->
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range_min(A,X),
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range_max(B,X),
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range_op(C, X)
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).
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range_min(Y, _X) -->
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{ var(Y) }, !,
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[].
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range_min(Y, X) -->
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[X #> Y].
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range_max(Y, _X) -->
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{ var(Y) }, !,
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[].
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range_max(Y, X) -->
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[X #< Y].
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range_op(Y, _X) -->
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{ var(Y) }, !,
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[].
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range_op(Y, X) -->
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{ Op =.. [Y, X] },
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[Op].
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insert_atts(V, Att) :-
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( nonvar(V) ->
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throw( error(uninstantion_error(V), exo_interval) )
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; attvar(V) ->
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get_attr(V, exo_interval, Att0),
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expand_atts(Att, Att0, NAtt)
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;
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NAtt = Att
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),
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put_attr(V, exo_interval, NAtt).
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expand_atts(i(A1, B1, C1), i(A2, B2, C2), i(A3,B3,C3)) :-
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expand_min(A1, A2, A3),
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expand_max(B1, B2, B3),
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expand_op(C1, C2, C3).
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expand_min(A1, A2, A3) :-
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(var(A1) -> A3 = A2;
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var(A2) -> A3 = A1;
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ground(A1), ground(A2) -> A3 is max(A1,A2) ;
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A3 = max(A1,A2)
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).
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expand_max(A1, A2, A3) :-
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(var(A1) -> A3 = A2;
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var(A2) -> A3 = A1;
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ground(A1), ground(A2) -> A3 is min(A1,A2) ;
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A3 = min(A1,A2)
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).
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expand_op(A1, A2, A3) :-
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(var(A1) -> A3 = A2;
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var(A2) -> A3 = A1;
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A1 == A2 -> A3 = A1;
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A1 == unique -> A3 = unique;
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A2 == unique -> A3 = unique;
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A2 == min, A1 = max -> A3 = unique;
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A1 == min, A2 = max -> A3 = unique;
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A1 == min -> A3 = min; A2 == min -> A3 = min;
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A1 == max -> A3 = max; A2 == max -> A3 = max;
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A3 = any
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).
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