/*
* Copyright 2013 Future Systems
*
* 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 org.araqne.logdb.query.aggregator;
import java.util.List;
import org.araqne.logdb.Row;
import org.araqne.logdb.ObjectComparator;
import org.araqne.logdb.query.expr.Expression;
public class Min extends AbstractAggregationFunction {
private ObjectComparator comp = new ObjectComparator();
private Object min;
public Min(List<Expression> exprs) {
super(exprs);
}
@Override
public String getName() {
return "min";
}
@Override
public void apply(Row map) {
Object obj = exprs.get(0).eval(map);
if (obj == null)
return;
put(obj);
}
private void put(Object obj) {
if (min == null || (comp.compare(min, obj) > 0 && obj != null))
min = obj;
}
public Object getMin() {
return min;
}
public void setMin(Object min) {
this.min = min;
}
@Override
public Object eval() {
return min;
}
@Override
public void clean() {
min = null;
}
@Override
public AggregationFunction clone() {
Min f = new Min(exprs);
f.min = min;
return f;
}
@Override
public Object[] serialize() {
Object[] l = new Object[1];
l[0] = min;
return l;
}
@Override
public void deserialize(Object[] values) {
this.min = values[0];
}
@Override
public void merge(AggregationFunction func) {
Min other = (Min) func;
put(other.min);
}
@Override
public String toString() {
return "min(" + exprs.get(0) + ")";
}
@Override
public boolean canBeDistributed() {
return true;
}
@Override
public AggregationFunction mapper(List<Expression> exprs) {
return new Min(exprs);
}
@Override
public AggregationFunction reducer(List<Expression> exprs) {
return new Min(exprs);
}
}