node.java

Java写的含有一个jdbc驱动的小型数据库数据库引擎

/*
 * Node.java
 *
 * Copyright (c) 2001, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This package is based on HypersonicSQL, originally developed by Thomas Mueller.
 *
 */
package org.hsqldb;

import java.sql.*;
import java.io.*;

/**
 * Class declaration
 *
 *
 * @version 1.0.0.1
 */
class Node {
    int		iBalance;    // currently, -2 means 'deleted'
    int		iLeft, iRight, iParent;
    Node	nLeft, nRight, nParent;
    private int iId;	     // id of index this table
    Node	nNext;    // node of next index (nNext==null || nNext.iId=iId+1)
    Row		rData;

    /**
     * Constructor declaration
     *
     *
     * @param r
     * @param in
     * @param id
     */
    Node(Row r, DataInput in, int id) throws IOException, SQLException {
	iId = id;
	rData = r;
	iBalance = in.readInt();
	iLeft = in.readInt();
	iRight = in.readInt();
	iParent = in.readInt();

	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}
    }

    /**
     * Constructor declaration
     *
     *
     * @param r
     * @param id
     */
    Node(Row r, int id) {
	iId = id;
	rData = r;
    }

    /**
     * Method declaration
     *
     */
    void delete() {
	iBalance = -2;
	nLeft = nRight = nParent = null;
	iLeft = iRight = iParent = 0;
    }

    /**
     * Method declaration
     *
     *
     * @return
     */
    int getKey() {
	return rData.iPos;
    }

    /**
     * Method declaration
     *
     *
     * @return
     *
     * @throws SQLException
     */
    Node getLeft() throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	if (iLeft == 0) {
	    return nLeft;
	}

	// rData.iLastAccess=Row.iCurrentAccess++;
	return rData.getNode(iLeft, iId);
    }

    /**
     * Method declaration
     *
     *
     * @param n
     *
     * @throws SQLException
     */
    void setLeft(Node n) throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	rData.changed();

	if (n == null) {
	    iLeft = 0;
	    nLeft = null;
	} else if (n.rData.iPos != 0) {
	    iLeft = n.rData.iPos;
	} else {
	    nLeft = n;
	}
    }

    /**
     * Method declaration
     *
     *
     * @return
     *
     * @throws SQLException
     */
    Node getRight() throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	if (iRight == 0) {
	    return nRight;
	}

	// rData.iLastAccess=Row.iCurrentAccess++;
	return rData.getNode(iRight, iId);
    }

    /**
     * Method declaration
     *
     *
     * @param n
     *
     * @throws SQLException
     */
    void setRight(Node n) throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	rData.changed();

	if (n == null) {
	    iRight = 0;
	    nRight = null;
	} else if (n.rData.iPos != 0) {
	    iRight = n.rData.iPos;
	} else {
	    nRight = n;
	}
    }

    /**
     * Method declaration
     *
     *
     * @return
     *
     * @throws SQLException
     */
    Node getParent() throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	if (iParent == 0) {
	    return nParent;
	}

	// rData.iLastAccess=Row.iCurrentAccess++;
	return rData.getNode(iParent, iId);
    }

    /**
     * Method declaration
     *
     *
     * @param n
     *
     * @throws SQLException
     */
    void setParent(Node n) throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	rData.changed();

	if (n == null) {
	    iParent = 0;
	    nParent = null;
	} else if (n.rData.iPos != 0) {
	    iParent = n.rData.iPos;
	} else {
	    nParent = n;
	}
    }

    /**
     * Method declaration
     *
     *
     * @return
     *
     * @throws SQLException
     */
    int getBalance() throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);

	    // rData.iLastAccess=Row.iCurrentAccess++;
	}

	return iBalance;
    }

    /**
     * Method declaration
     *
     *
     * @param b
     *
     * @throws SQLException
     */
    void setBalance(int b) throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	if (iBalance != b) {
	    rData.changed();

	    iBalance = b;
	}
    }

    /**
     * Method declaration
     *
     *
     * @return
     *
     * @throws SQLException
     */
    public Object[] getData() throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	return rData.getData();
    }

    /**
     * Method declaration
     *
     *
     * @param n
     *
     * @return
     *
     * @throws SQLException
     */
    boolean equals(Node n) throws SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);

	    // rData.iLastAccess=Row.iCurrentAccess++;
	}

	if (Trace.ASSERT) {
	    if (n != this) {
		Trace.assert(rData.iPos == 0 || n == null
			     || n.rData.iPos != rData.iPos);
	    } else {
		Trace.assert(n.rData.iPos == rData.iPos);
	    }
	}

	return n == this;
    }

    /**
     * Method declaration
     *
     *
     * @param out
     *
     * @throws IOException
     * @throws SQLException
     */
    void write(DataOutput out) throws IOException, SQLException {
	if (Trace.ASSERT) {
	    Trace.assert(iBalance != -2);
	}

	out.writeInt(iBalance);
	out.writeInt(iLeft);
	out.writeInt(iRight);
	out.writeInt(iParent);

	if (nNext != null) {
	    nNext.write(out);
	}
    }

}