/**
* Copyright (C) 2009-2013 FoundationDB, LLC
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.foundationdb.sql.optimizer.plan;
/** A source that never outputs any rows. */
public class NullSource extends BaseJoinable implements ColumnSource
{
public NullSource() {
}
@Override
public String getName() {
return "NULL";
}
@Override
public boolean isTable() {
return false;
}
@Override
public boolean accept(PlanVisitor v) {
return v.visit(this);
}
@Override
protected boolean maintainInDuplicateMap() {
return true;
}
}