Include Paulo Moura's Logtalk OO LP system

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@53 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

Logtalk/examples/searching/breadth_first1.lgt

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+
+:- object(breadth_first(Bound),
+	instantiates(blind_search(Bound))).
+
+
+	:- info([
+		version is 1.0,
+		authors is 'Paulo Moura',
+		date is 1998/3/23,
+		comment is 'Breadth first state space search strategy.',
+		parnames is ['Bound']]).
+
+
+	:- calls(state_space).
+
+
+	:- uses(list).
+
+
+	search(Space, State, Bound, Solution) :-
+		breadt(Space, l(State), Bound, Path),
+		list::reverse(Path, Solution).
+
+
+	breadt(Space, Tree, Bound, Solution) :-
+		expand([], Tree, Tree2, Solved, Solution, Space, Bound),
+		(Solved ->
+			true
+			;
+			breadt(Space, Tree2, Bound, Solution)).
+
+
+	expand(Path, l(State), _, true, [State| Path], Space, _) :-
+		Space::goal_state(State).
+
+	expand(Path, l(State), t(State, Subs), fail, _, Space, Bound) :-
+		Bound > 0,
+		bagof(l(Next),
+			(Space::next_state(State, Next),
+			\+ list::member(Next, [State| Path])),
+			Subs).
+
+	expand(Path, t(State,Subs), t(State, Subs2), Solved, Solution, Space, Bound) :-
+		expandall([State| Path], Subs, [], Subs2, Solved, Solution, Space, Bound).
+
+
+	expandall(_, [], [Tree| Trees], [Tree| Trees], fail, _, _, _).
+
+	expandall(Path, [Tree| Trees], Trees2, Subs2, Solved, Solution, Space, Bound) :-
+		Bound > 0,
+		Bound2 is Bound -1,
+		expand(Path, Tree, Tree2, Solved2, Solution, Space, Bound2),
+		(Solved2 ->
+			Solved = true
+			;
+			expandall(Path, Trees, [Tree2| Trees2], Subs2, Solved, Solution, Space, Bound))
+		;
+		expandall(Path, Trees, Trees2, Subs2, Solved, Solution, Space, Bound).
+
+
+:- end_object.