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Immutable map applying a spatial index to keys based on R-Trees
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package com.jamieswhiteshirt.rtree3i;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

import com.google.common.base.Preconditions;

/**
 * @author dxm
 *
 */
final class Util {

    private Util() {
        // prevent instantiation
    }

    /**
     * Returns the minimum bounding box of a number of items. Benchmarks
     * below indicate that when the number of items is >1 this method is more
     * performant than one using {@link Box#add(Box)}.
     *
     * @param items
     *            items to bound
     * @return the minimum bounding box containings items
     */
    static Box mbb(Collection items) {
        Preconditions.checkArgument(!items.isEmpty());
        int minX1 = Integer.MAX_VALUE;
        int minY1 = Integer.MAX_VALUE;
        int minZ1 = Integer.MAX_VALUE;
        int maxX2 = -Integer.MAX_VALUE;
        int maxY2 = -Integer.MAX_VALUE;
        int maxZ2 = -Integer.MAX_VALUE;
        for (final Box r : items) {
            if (r.x1() < minX1)
                minX1 = r.x1();
            if (r.y1() < minY1)
                minY1 = r.y1();
            if (r.z1() < minZ1)
                minZ1 = r.z1();
            if (r.x2() > maxX2)
                maxX2 = r.x2();
            if (r.y2() > maxY2)
                maxY2 = r.y2();
            if (r.z2() > maxZ2)
                maxZ2 = r.z2();
        }
        return Box.create(minX1, minY1, minZ1, maxX2, maxY2, maxZ2);
    }

    static  List add(List list, T element) {
        final ArrayList result = new ArrayList<>(list.size() + 1);
        result.addAll(list);
        result.add(element);
        return result;
    }

    static  List remove(List list, List elements) {
        final ArrayList result = new ArrayList<>(list);
        result.removeAll(elements);
        return result;
    }

    static  List remove(List list, T element) {
        final ArrayList result = new ArrayList<>(list);
        result.remove(element);
        return result;
    }

    static  List replace(List list, T toReplace, T replacement) {
        List list2 = new ArrayList<>(list.size());
        for (T element : list) {
            list2.add(element != toReplace ? element : replacement);
        }
        return list2;
    }

    static  List replace(List list, T toReplace, List replacements) {
        List list2 = new ArrayList<>(list.size() - 1 + replacements.size());
        for (T node : list) {
            if (node != toReplace) {
                list2.add(node);
            }
        }
        list2.addAll(replacements);
        return list2;
    }

}