//
//	stack based general search engine

import jds.Stack;
import jds.collection.Vector;

class SearchEngine {

	public SearchEngine (SearchState initialState) {
			// create data statck with one initial state
		states.addLast(initialState);
	}

	Stack states = new Vector();

	public void run () {
		while (! states.isEmpty()) {
			SearchState current = (SearchState) states.getLast();
			try {
				SearchState next = current.advance();
				states.addLast(next);
			}
			catch (CannotAdvance e) { states.removeLast(); }
			catch (SearchDone e) { return; }
		}
	}
}