PathingStrategy.java

import java.util.List;
import java.util.function.BiPredicate;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;

public interface PathingStrategy{
    /*Returns a prefix of a path from the start point to a point within reach of the end point.  This path is only valid ("clear") when returned, but may be invalidated by movement of other entities. The prefix includes neither the start point nor the end point.
     */
    List<Point> computePath(Point start, Point end,
                            Predicate<Point> canPassThrough,
                            BiPredicate<Point, Point> withinReach,
                            Function<Point, Stream<Point>> potentialNeighbors);

    static final Function<Point, Stream<Point>> CARDINAL_NEIGHBORS =
        point ->
            Stream.<Point>builder()
                .add(new Point(point.getX(), point.getY() - 1))
                .add(new Point(point.getX(), point.getY() + 1))
                .add(new Point(point.getX() - 1, point.getY()))
                .add(new Point(point.getX() + 1, point.getY()))
                .build();
}