org.jgrasstools.gears.io.disktree.jtstmp.NodeBase Maven / Gradle / Ivy

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package org.jgrasstools.gears.io.disktree.jtstmp;

import java.io.Serializable;
import java.util.*;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.index.*;

/**
 * The base class for nodes in a {@link Quadtree}.
 *
 * @version 1.7
 */
public abstract class NodeBase implements Serializable {

    // <> Several classes in the various tree packages have the
    // same name and duplicate code. This suggests that there should be a generic
    // tree package containing the code that is duplicated, perhaps in abstract
    // base classes. [Jon Aquino]

    // <> This little class hierarchy has some naming/conceptual
    // problems. A root node is conceptually a kind of node, yet a Root is not a Node.
    // NodeBase begs to be called BaseNode, but not all BaseNodes would be Nodes
    // (for example, Root). [Jon Aquino]

    private static final long serialVersionUID = -5033486556084549819L;

    // DEBUG private static int itemCount = 0; // debugging
    /**
     * Returns the index of the subquad that wholly contains the given envelope.
     * If none does, returns -1.
     */
    public static int getSubnodeIndex( Envelope env, Coordinate centre ) {
        int subnodeIndex = -1;
        if (env.getMinX() >= centre.x) {
            if (env.getMinY() >= centre.y)
                subnodeIndex = 3;
            if (env.getMaxY() <= centre.y)
                subnodeIndex = 1;
        }
        if (env.getMaxX() <= centre.x) {
            if (env.getMinY() >= centre.y)
                subnodeIndex = 2;
            if (env.getMaxY() <= centre.y)
                subnodeIndex = 0;
        }
        return subnodeIndex;
    }

    protected List items = new ArrayList();

    /**
     * subquads are numbered as follows:
     *      *  2 | 3
     *  --+--
     *  0 | 1
     * 
     */
    protected Node[] subnode = new Node[4];

    public NodeBase() {
    }

    public List getItems() {
        return items;
    }

    public boolean hasItems() {
        return !items.isEmpty();
    }

    public void add( Object item ) {
        items.add(item);
        // DEBUG itemCount++;
        // DEBUG System.out.print(itemCount);
    }

    /**
     * Removes a single item from this subtree.
     *
     * @param itemEnv the envelope containing the item
     * @param item the item to remove
     * @return true if the item was found and removed
     */
    public boolean remove( Envelope itemEnv, Object item ) {
        // use envelope to restrict nodes scanned
        if (!isSearchMatch(itemEnv))
            return false;

        boolean found = false;
        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                found = subnode[i].remove(itemEnv, item);
                if (found) {
                    // trim subtree if empty
                    if (subnode[i].isPrunable())
                        subnode[i] = null;
                    break;
                }
            }
        }
        // if item was found lower down, don't need to search for it here
        if (found)
            return found;
        // otherwise, try and remove the item from the list of items in this node
        found = items.remove(item);
        return found;
    }

    public boolean isPrunable() {
        return !(hasChildren() || hasItems());
    }

    public boolean hasChildren() {
        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null)
                return true;
        }
        return false;
    }

    public boolean isEmpty() {
        boolean isEmpty = true;
        if (!items.isEmpty())
            isEmpty = false;
        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                if (!subnode[i].isEmpty())
                    isEmpty = false;
            }
        }
        return isEmpty;
    }

    // <> Sounds like this method adds resultItems to items
    // (like List#addAll). Perhaps it should be renamed to "addAllItemsTo" [Jon Aquino]
    public List addAllItems( List resultItems ) {
        // this node may have items as well as subnodes (since items may not
        // be wholely contained in any single subnode
        resultItems.addAll(this.items);
        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                subnode[i].addAllItems(resultItems);
            }
        }
        return resultItems;
    }
    protected abstract boolean isSearchMatch( Envelope searchEnv );

    public void addAllItemsFromOverlapping( Envelope searchEnv, List resultItems ) {
        if (!isSearchMatch(searchEnv))
            return;

        // this node may have items as well as subnodes (since items may not
        // be wholely contained in any single subnode
        resultItems.addAll(items);

        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                subnode[i].addAllItemsFromOverlapping(searchEnv, resultItems);
            }
        }
    }

    public void visit( Envelope searchEnv, ItemVisitor visitor ) {
        if (!isSearchMatch(searchEnv))
            return;

        // this node may have items as well as subnodes (since items may not
        // be wholely contained in any single subnode
        visitItems(searchEnv, visitor);

        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                subnode[i].visit(searchEnv, visitor);
            }
        }
    }

    private void visitItems( Envelope searchEnv, ItemVisitor visitor ) {
        // would be nice to filter items based on search envelope, but can't until they contain an
        // envelope
        for( Iterator i = items.iterator(); i.hasNext(); ) {
            visitor.visitItem(i.next());
        }
    }

    // <> In Samet's terminology, I think what we're returning here is
    // actually level+1 rather than depth. (See p. 4 of his book) [Jon Aquino]
    int depth() {
        int maxSubDepth = 0;
        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                int sqd = subnode[i].depth();
                if (sqd > maxSubDepth)
                    maxSubDepth = sqd;
            }
        }
        return maxSubDepth + 1;
    }

    int size() {
        int subSize = 0;
        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                subSize += subnode[i].size();
            }
        }
        return subSize + items.size();
    }

    int getNodeCount() {
        int subSize = 0;
        for( int i = 0; i < 4; i++ ) {
            if (subnode[i] != null) {
                subSize += subnode[i].size();
            }
        }
        return subSize + 1;
    }

}