arraynavigator.java

来自「数据仓库展示程序」· Java 代码 · 共 131 行

/*
// $Id: //open/mondrian/src/main/mondrian/jolap/ArrayNavigator.java#3 $
// This software is subject to the terms of the Common Public License
// Agreement, available at the following URL:
// http://www.opensource.org/licenses/cpl.html.
// (C) Copyright 2002-2005 Kana Software, Inc. and others.
// All Rights Reserved.
// You must accept the terms of that agreement to use this software.
//
// jhyde, Dec 25, 2002
*/
package mondrian.jolap;

import javax.olap.OLAPException;

/**
 * Provides methods for cursor-like navigation ({@link #next}, {@link
 * #previous}, {@link #isBeforeFirst}, and so forth) over an array of objects.
 *
 * @author jhyde
 * @since Dec 25, 2002
 * @version $Id: //open/mondrian/src/main/mondrian/jolap/ArrayNavigator.java#3 $
 **/
class ArrayNavigator {
    private Object[] a;
    private int position;

    public ArrayNavigator(Object[] a) {
        super();
        this.a = a;
        this.position = -1;
    }

    public boolean next() throws OLAPException {
        position++;
        if (position < a.length) {
            return true;
        } else {
            position = a.length;
            return false;
        }
    }

    public boolean previous() throws OLAPException {
        position--;
        if (position >= 0) {
            return true;
        } else {
            position = -1;
            return false;
        }
    }

    public boolean relative(int arg0) throws OLAPException {
        position += arg0;
        if (position >= a.length) {
            position = a.length;
            return false;
        } else if (position < 0) {
            position = 0;
            return false;
        } else {
            return true;
        }
    }

    public boolean first() throws OLAPException {
        if (a.length > 0) {
            position = 0;
            return true;
        } else {
            return false;
        }
    }

    public boolean last() throws OLAPException {
        if (a.length > 0) {
            position = a.length - 1;
            return true;
        } else {
            return false;
        }
    }

    public boolean isBeforeFirst() {
        return position < 0;
    }

    public boolean isAfterLast() throws OLAPException {
        return position >= a.length;
    }

    public boolean isFirst() throws OLAPException {
        return position == 0;
    }

    public boolean isLast() throws OLAPException {
        return position == a.length - 1;
    }

    public void afterLast() throws OLAPException {
        position = a.length;
    }

    public void beforeFirst() throws OLAPException {
        position = -1;
    }

    // todo: spec: what happens if position is out of range?
    public void setPosition(long position) throws OLAPException {
        this.position = (int) position;
    }

    public long getPosition() throws OLAPException {
        return position;
    }

    /**
     * Returns the object representing the current row. Throws an exception if
     * the cursor is not positioned properly.
     *
     * todo: spec: what should happen if they call say getString(4) and the
     * cursor is not positioned
     */
    protected Object current() {
        return a[position];
    }
}

// End ArrayCursor.java