:- object(point,
	instantiates(class),
	specializes(object)).


	:- info([
		version is 1.1,
		date is 2000/10/31,
		author is 'Paulo Moura',
		comment is 'Two dimensional point class.',
		source is 'Example adopted from the SICStus Objects documentation.']).


	:- public(move/2).
	:- mode(move(+integer, +integer), zero_or_one).

	:- public(position/2).
	:- mode(position(?integer, ?integer), one).

	:- private(position_/2).
	:- dynamic(position_/2).
	:- mode(position_(?integer, ?integer), one).


	move(X, Y) :-
		::retractall(position_(_, _)),
		::assertz(position_(X, Y)).


	position(X, Y) :-
		::position_(X, Y).


	print :-
		self(Self),
		::position_(X, Y),
		writeq(Self), write(' @ '), write((X, Y)), nl.


	default_init_option(position-(0, 0)).

	default_init_option(Default) :-
		^^default_init_option(Default).


	process_init_option(position-(X, Y)) :-
		::assertz(position_(X, Y)).

	process_init_option(Option) :-
		^^process_init_option(Option).


	instance_base_name(p).


:- end_object.




:- category(bounded_coordinate).


	:- info([
		version is 1.0,
		date is 1998/3/23,
		author is 'Paulo Moura',
		comment is 'Point coordinate bounds management predicates.',
		source is 'Example adopted from the SICStus Objects documentation.']).


	:- public(set_bounds/3).
	:- mode(set_bounds(+atom, +integer, +integer), one).

	:- public(clear_bounds/1).
	:- mode(clear_bounds(+atom), one).

	:- public(bounds/3).
	:- mode(bounds(?atom, ?integer, ?integer), zero_or_more).

	:- public(check_bounds/2).
	:- mode(check_bounds(+atom, +integer), zero_or_one).

	:- public(print_bounds/1).
	:- mode(print_bounds(?atom), zero_or_more).

	:- public(valid_value/2).
	:- mode(valid_value(+atom, +integer), zero_or_one).

	:- private(bounds_/3).
	:- dynamic(bounds_/3).
	:- mode(bounds_(?atom, ?integer, ?integer), zero_or_more).


	set_bounds(Coordinate, Min, Max) :-
		::retractall(bounds_(Coordinate, _, _)),
		::assertz(bounds_(Coordinate, Min, Max)).


	clear_bounds(Coordinate) :-
		::retractall(bounds_(Coordinate, _, _)).


	bounds(Coordinate, Min, Max) :-
		::bounds_(Coordinate, Min, Max).


	check_bounds(Coordinate, Value) :-
		::bounds_(Coordinate, Min, Max),
		Value >= Min,
		Value =< Max.


	print_bounds(Coordinate) :-
		::bounds_(Coordinate, Min, Max),
		writeq(bounds(Coordinate)),
		write(' : '),
		write((Min, Max)),
		nl.


	valid_value(Coordinate, Value) :-
		::bounds_(Coordinate, Min, Max) ->
			Value >= Min, Value =< Max
			;
			true.


:- end_category.




:- object(bounded_point,
	imports(bounded_coordinate),
	instantiates(class),
	specializes(point)).


	:- info([
		version is 1.1,
		date is 2000/10/31,
		author is 'Paulo Moura',
		comment is 'Two dimensional point moving in a constrained area.',
		source is 'Example adopted from the SICStus Objects documentation.']).


	move(X, Y) :-
		::check_bounds(x, X),
		::check_bounds(y, Y),
		^^move(X, Y).


	print :-
		::print_bounds(x),
		::print_bounds(y),
		^^print.


	instance_base_name(bp).


	default_init_option(bounds(x)-(-10, 10)).

	default_init_option(bounds(y)-(-10, 10)).

	default_init_option(Default) :-
		^^default_init_option(Default).


	process_init_option(bounds(Coordinate)-(Min, Max)) :-
		::set_bounds(Coordinate, Min, Max).

	process_init_option(Option) :-
		^^process_init_option(Option).


:- end_object.




:- category(point_history).


	:- info([
		version is 1.0,
		date is 1998/3/23,
		author is 'Paulo Moura',
		comment is 'Point position history management predicates.',
		source is 'Example adopted from the SICStus Objects documentation.']).


	:- public(add_to_history/1).
	:- mode(add_to_history(+nonvar), one).

	:- public(init_history/1).
	:- mode(init_history(+list), one).

	:- public(history/1).
	:- mode(history(-list), zero_or_one).

	:- public(print_history/0).
	:- mode(print_history, zero_or_one).

	:- private(history_/1).
	:- dynamic(history_/1).
	:- mode(history_(-list), zero_or_one).


	add_to_history(Location) :-
		::retract(history_(History)),
		::assertz(history_([Location| History])).


	init_history(History) :-
		::retractall(history_(_)),
		::assertz(history_(History)).


	history(History) :-
		::history_(History).


	print_history :-
		::history_(History),
		write('location history: '),
		write(History),
		nl.


:- end_category.




:- object(history_point,
	imports(point_history),
	instantiates(class),
	specializes(point)).


	:- info([
		version is 1.1,
		date is 2000/10/31,
		author is 'Paulo Moura',
		comment is 'Two dimensional point remembering past positions.',
		source is 'Example adopted from the SICStus Objects documentation.']).


	move(X, Y) :-
		::position(OldX, OldY),
		^^move(X, Y),
		::add_to_history((OldX, OldY)).


	print :-
		::print_history,
		^^print.


	instance_base_name(hp).


	default_init_option(history-[]).

	default_init_option(Default) :-
		^^default_init_option(Default).


	process_init_option(history-History) :-
		::init_history(History).

	process_init_option(Option) :-
		^^process_init_option(Option).


:- end_object.




:- object(bounded_history_point,
	imports(bounded_coordinate, point_history),
	instantiates(class),
	specializes(point)).


	:- info([
		version is 1.1,
		date is 2000/10/31,
		author is 'Paulo Moura',
		comment is 'Two dimensional point moving in a constrained area and remembering past point positions.',
		source is 'Example adopted from the SICStus Objects documentation.']).


	move(X, Y) :-
		::check_bounds(x, X),
		::check_bounds(y, Y),
		::position(OldX, OldY),
		^^move(X, Y),
		::add_to_history((OldX, OldY)).


	print :-
		::print_bounds(x),
		::print_bounds(y),
		::print_history,
		^^print.


	instance_base_name(bhp).


	default_init_option(history-[]).

	default_init_option(bounds(x)-(-10, 10)).

	default_init_option(bounds(y)-(-10, 10)).

	default_init_option(Default) :-
		^^default_init_option(Default).


	process_init_option(history-History) :-
		::init_history(History).

	process_init_option(bounds(Coordinate)-(Min, Max)) :-
		::set_bounds(Coordinate, Min, Max).

	process_init_option(Option) :-
		^^process_init_option(Option).


:- end_object.