com.healthmarketscience.jackcess.impl.RowIdImpl.java Source code

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Here is the source code for com.healthmarketscience.jackcess.impl.RowIdImpl.java

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/*
Copyright (c) 2007 Health Market Science, Inc.
    
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
    
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.
    
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
USA
    
You can contact Health Market Science at info@healthmarketscience.com
or at the following address:
    
Health Market Science
2700 Horizon Drive
Suite 200
King of Prussia, PA 19406
*/

package com.healthmarketscience.jackcess.impl;

import java.io.Serializable;

import com.healthmarketscience.jackcess.RowId;
import org.apache.commons.lang.builder.CompareToBuilder;

/**
 * Uniquely identifies a row of data within the access database.
 *
 * @author James Ahlborn
 */
public class RowIdImpl implements RowId, Serializable {
    private static final long serialVersionUID = 20131014L;

    /** special page number which will sort before any other valid page
        number */
    public static final int FIRST_PAGE_NUMBER = -1;
    /** special page number which will sort after any other valid page
        number */
    public static final int LAST_PAGE_NUMBER = -2;

    /** special row number representing an invalid row number */
    public static final int INVALID_ROW_NUMBER = -1;

    /** type attributes for RowIds which simplify comparisons */
    public enum Type {
        /** comparable type indicating this RowId should always compare less than
            normal RowIds */
        ALWAYS_FIRST,
        /** comparable type indicating this RowId should always compare
            normally */
        NORMAL,
        /** comparable type indicating this RowId should always compare greater
            than normal RowIds */
        ALWAYS_LAST;
    }

    /** special rowId which will sort before any other valid rowId */
    public static final RowIdImpl FIRST_ROW_ID = new RowIdImpl(FIRST_PAGE_NUMBER, INVALID_ROW_NUMBER);

    /** special rowId which will sort after any other valid rowId */
    public static final RowIdImpl LAST_ROW_ID = new RowIdImpl(LAST_PAGE_NUMBER, INVALID_ROW_NUMBER);

    private final int _pageNumber;
    private final int _rowNumber;
    private final Type _type;

    /**
     * Creates a new <code>RowId</code> instance.
     *
     */
    public RowIdImpl(int pageNumber, int rowNumber) {
        _pageNumber = pageNumber;
        _rowNumber = rowNumber;
        _type = ((_pageNumber == FIRST_PAGE_NUMBER) ? Type.ALWAYS_FIRST
                : ((_pageNumber == LAST_PAGE_NUMBER) ? Type.ALWAYS_LAST : Type.NORMAL));
    }

    public int getPageNumber() {
        return _pageNumber;
    }

    public int getRowNumber() {
        return _rowNumber;
    }

    /**
     * Returns {@code true} if this rowId potentially represents an actual row
     * of data, {@code false} otherwise.
     */
    public boolean isValid() {
        return ((getRowNumber() >= 0) && (getPageNumber() >= 0));
    }

    public Type getType() {
        return _type;
    }

    public int compareTo(RowId other) {
        return compareTo((RowIdImpl) other);
    }

    public int compareTo(RowIdImpl other) {
        return new CompareToBuilder().append(getType(), other.getType())
                .append(getPageNumber(), other.getPageNumber()).append(getRowNumber(), other.getRowNumber())
                .toComparison();
    }

    @Override
    public int hashCode() {
        return getPageNumber() ^ getRowNumber();
    }

    @Override
    public boolean equals(Object o) {
        return ((this == o) || ((o != null) && (getClass() == o.getClass())
                && (getPageNumber() == ((RowIdImpl) o).getPageNumber())
                && (getRowNumber() == ((RowIdImpl) o).getRowNumber())));
    }

    @Override
    public String toString() {
        return getPageNumber() + ":" + getRowNumber();
    }

}