root/trunk/examples/searching/heuristic_search1.lgt

:- object(heuristic_search(_),
    instantiates(class),
    specializes(search_strategy)).

    :- info([
        version is 1.0,
        author is 'Paulo Moura',
        date is 1998/3/23,
        comment is 'Heuristic state space search strategies.',
        parnames is ['Threshold']]).

    :- public(threshold/1).
    :- mode(threshold(?number), one).
    :- info(threshold/1,
        [comment is 'Search cost threshold.',
         argnames is ['Threshold']]).

    :- public(solve/4).
    :- mode(solve(+object, +nonvar, -list, -number), zero_or_more).
    :- info(solve/4,
        [comment is 'State space search solution.',
         argnames is ['Space', 'State', 'Path', 'Cost']]).

    :- protected(search/5).
    :- mode(search(+object, +nonvar, +number, -list, -number), zero_or_more).
    :- info(search/5,
        [comment is 'State space search solution.',
         argnames is ['Space', 'State', 'Threshold', 'Path', 'Cost']]).

    solve(Space, State, Path) :-
        ::solve(Space, State, Path, _).

    solve(Space, State, Path, Cost) :-
        ::threshold(Threshold),
        ::search(Space, State, Threshold, Path, Cost).

    threshold(Threshold) :-
        parameter(1, Threshold).

:- end_object.