//Excerpt from visionary.C.

class closest_enemy_to {
	const wabbit *const w;
public:
	closest_enemy_to(const wabbit* initial_w): w(initial_w) {}

	//Return true if w1 is a closer enemy of w than w2 is.

	bool operator()(const wabbit *w1, const wabbit *w2) const {

		//If w1 is not an enemy of w, return false.
		if (w1 == w || w1->hungry() <= w->bitter()) {
			return false;
		}

		//Arrive here if w1 is an enemy of w.
		//If w2 is not an enemy of w, return true.
		if (w2 == w || w2->hungry() <= w->bitter()) {
			return true;
		}

		//Arrive here if w1 and w2 are both enemies of w.
		return distance(w1, w) < distance(w2, w);
	}
};