com.livae.util.tree.Btree Maven / Gradle / Ivy

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package com.livae.util.tree;

import com.livae.util.ResourcesFactory;

public class Btree> extends ResourcesFactory> {

	private static final int NODES_PER_PAGE = 6;

	private long size;

	private BtreePage root;

	private int nodesPerPage;

	private VisitStructure orderVisitor;

	public Btree() {
		this(NODES_PER_PAGE);
	}

	public Btree(int nodesPerPage) {
		if (nodesPerPage < 3) {
			throw new RuntimeException("Nodes per page must be greater than 2");
		}
		this.nodesPerPage = nodesPerPage;
		this.root = getResource();
		this.size = 0;
	}

	private Btree(Btree treeToClone) {
		size = treeToClone.size;
		nodesPerPage = treeToClone.nodesPerPage;
		root = treeToClone.root.clone(null, this);
	}

	public Btree clone() {
		return new Btree(this);
	}

	public void add(k object) {
		size++;
		root.add(object);
	}

	public k getFirst() {
		k object = null;
		if (root != null) {
			BtreePage firstPage = root.getFirstPage();
			object = firstPage.getFirstFromPage();
			if (firstPage.remove(object)) {
				size--;
			}
		}
		return object;
	}

	public void remove(k object) {
		if (root.remove(object)) {
			size--;
		}
	}

	public long getSize() {
		return this.size;
	}

	public boolean isEmpty() {
		return this.size == 0;
	}

	public void visitInOrder(BtreeVisitor visitor) {
		this.root.visitInOrder(visitor, 0);
	}

	public void checkStructure() {
		root.checkIntegrity();
		if (orderVisitor == null) {
			orderVisitor = new VisitStructure();
		}
		orderVisitor.orderVisitorPrevious = null;
		orderVisitor.visited = 0;
		//noinspection unchecked
		visitInOrder((BtreeVisitor) orderVisitor);
		if (orderVisitor.visited != size) {
			System.out.println(getDebugString());
			throw new RuntimeException("Different nodes than expected visited: " +
			                           orderVisitor.visited + " != " + size);
		}
	}

	@Override
	protected BtreePage createResource() {
		return new BtreePage(this.nodesPerPage, this);
	}

	public void clear() {
		root.clear();
	}

	public String getDebugString() {
		return root.getDebugString();
	}

	protected TestUtils getTestUtils() {
		return new TestUtils();
	}

	class VisitStructure implements BtreeVisitor {

		Comparable orderVisitorPrevious;

		int visited;

		@Override
		public void visit(final Comparable object, final int deep) {
			//noinspection unchecked
			if (orderVisitorPrevious != null && orderVisitorPrevious.compareTo(object) > 0) {
				throw new RuntimeException("Wrong order: " + orderVisitorPrevious + " < " +
				                           object);
			}
			visited++;
			orderVisitorPrevious = object;
		}
	}

	class TestUtils {

		public void setRoot(Btree o, BtreePage page, int size) {
			o.root = page;
			o.size = size;
		}
	}

}