cellreader.java

来自「数据仓库展示程序」· Java 代码 · 共 47 行

/*
// $Id: //open/mondrian/src/main/mondrian/rolap/CellReader.java#5 $
// 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 2001-2005 Kana Software, Inc. and others.
// All Rights Reserved.
// You must accept the terms of that agreement to use this software.
//
// jhyde, 10 August, 2001
*/

package mondrian.rolap;
import mondrian.olap.CubeBase;
import mondrian.olap.Evaluator;
import mondrian.olap.Util;

/**
 * A <code>CellReader</code> finds the cell value for the current context
 * held by <code>evaluator</code>.
 *
 * <p>It returns:<ul>
 * <li><code>null</code> if the source is unable to evaluate the cell (for
 *   example, {@link RolapResult.AggregatingCellReader} does not have the cell
 *   in its cache). This value should only be returned if the caller is
 *   expecting it.</li>
 * <li>{@link Util#nullValue} if the cell evaluates to null</li>
 * <li>{@link mondrian.olap.Util.ErrorCellValue} if the cell evaluates to an
 *   error</li>
 * <li>an Object representing a value (often a {@link Double} or a {@link
 *   java.math.BigDecimal}), otherwise</li>
 * </ul>
 *
 * @author jhyde
 * @since 10 August, 2001
 * @version $Id: //open/mondrian/src/main/mondrian/rolap/CellReader.java#5 $
 **/
interface CellReader {
    /**
     * Returns the value of the cell which has the context described by the
     * evaluator.
     */
    Object get(Evaluator evaluator);
}

// End CellReader.java