/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.addthis.hydra.data.query.op;
import com.addthis.bundle.core.Bundle;
import com.addthis.bundle.table.DataTable;
import com.addthis.bundle.table.DataTableFactory;
import com.addthis.hydra.data.query.AbstractTableOp;
import io.netty.channel.ChannelProgressivePromise;
/**
* <p>This query operation <span class="hydra-summary">reverses the ordering of rows</span>.
* <p/>
* <p>In a table with rows numbered 1,2,..,N-1,N, this operation moves row 1 to row N,
* row 2 to row N-1, ..., row N-1 to row 2, and row N to row 1.</p>
*
* @user-reference
* @hydra-name reverse
*/
public class OpReverse extends AbstractTableOp {
public OpReverse(DataTableFactory processor, ChannelProgressivePromise queryPromise) {
super(processor, queryPromise);
}
@Override
public DataTable tableOp(DataTable result) {
int size = result.size();
for (int i = 0; i < size / 2; i++) {
Bundle a = result.get(i);
Bundle b = result.get(size - i - 1);
result.set(size - i - 1, a);
result.set(i, b);
}
return result;
}
}