PredicatedPositionableList.java

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package jsettlers.logic.map.grid.partition.manager.datastructures;

import java8.util.function.Predicate;
import jsettlers.common.position.ILocatable;
import jsettlers.common.position.ShortPoint2D;
import jsettlers.common.utils.MathUtils;

/**
 * This is a data structure for storing and retrieving objects at given positions.<br>
 * It is also possible to find the nearest object around a given position.
 *
 * @param <T>
 * @author Andreas Eberle
 */
public class PredicatedPositionableList<T extends ILocatable> extends PositionableList<T> {

	/**
	 * Finds the object that's closest to the given position and removes it.
	 *
	 * @param position
	 * 		position to be used to find the nearest accepted neighbor around it.
	 * @param predicate
	 * 		if predicate != null => the result is accepted by the predicate. <br>
	 * 		if result == null every entry is accepted.
	 * @return accepted object that's nearest to position
	 */
	public T removeObjectNextTo(ShortPoint2D position, Predicate<T> predicate) {
		T currBest = getObjectCloseTo(position, predicate);

		if (currBest != null) {
			data.remove(currBest);
		}

		return currBest;
	}

	private T getObjectCloseTo(ShortPoint2D position, Predicate<T> acceptor) {
		int bestDistance = Integer.MAX_VALUE;
		T currBest = null;

		for (T currEntry : data) {
			if (acceptor != null && !acceptor.test(currEntry)) {
				continue;
			}

			int currDist = MathUtils.squareHypot(position, currEntry.getPos());

			if (bestDistance > currDist) {
				bestDistance = currDist;
				currBest = currEntry;
			}
		}
		return currBest;
	}
}