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/*

 Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016.  All rights reserved.

 Contact:
 SYSTAP, LLC DBA Blazegraph
 2501 Calvert ST NW #106
 Washington, DC 20008
 [email protected]

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; version 2 of the License.

 This program 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 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */
package com.bigdata.sparse;

import com.bigdata.btree.IIndex;


/**
 * Atomic read of the logical row associated with some {@link Schema} and
 * primary key.
 * 
 * @author Bryan Thompson
 */
public class AtomicRowRead extends AbstractAtomicRowReadOrWrite {

    /**
     * 
     */
    private static final long serialVersionUID = 7240920229720302721L;

    @Override
    public final boolean isReadOnly() {
        
        return true;
        
    }
        
    /**
     * De-serialization ctor.
     */
    public AtomicRowRead() {
        
    }
    
    /**
     * Constructor for an atomic read operation.
     * 
     * @param schema
     *            The schema governing the property set.
     * @param primaryKey
     *            The value of the primary key (identifies the logical row
     *            to be read).
     * @param fromTime
     *            During pre-condition and post-condition reads, the
     *            first timestamp for which timestamped property values will be
     *            accepted.
     * @param toTime
     *            During pre-condition and post-condition reads, the
     *            first timestamp for which timestamped property values will NOT
     *            be accepted -or- {@link IRowStoreConstants#CURRENT_ROW} to
     *            accept only the most current binding whose timestamp is GTE
     *            fromTime.
     * @param filter
     *            An optional filter used to restrict the property values
     *            that will be returned.
     */
    public AtomicRowRead(final Schema schema, final Object primaryKey,
            final long fromTime, final long toTime, final INameFilter filter) {
        
        super(schema, primaryKey, fromTime, toTime, filter);
        
    }
    
    /**
     * Atomic read.
     * 
     * @return A {@link TPS} instance containing the selected data from the
     *         logical row identified by the {@link #primaryKey} -or-
     *         null iff the primary key was NOT FOUND in the
     *         index. I.e., iff there are NO entries for that primary key
     *         regardless of whether or not they were selected.
     */
    @Override
	public TPS apply(final IIndex ndx) {
    
        return atomicRead(ndx, schema, primaryKey, fromTime, toTime,
                0L/* writeTime */, filter);
        
    }

}