/*
* Copyright 2013, Mysema Ltd
*
* 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.mysema.query.group;
import java.util.List;
import com.google.common.base.Objects;
import com.google.common.collect.Lists;
import com.mysema.commons.lang.CloseableIterator;
import com.mysema.query.Projectable;
import com.mysema.query.Tuple;
import com.mysema.query.types.Expression;
import com.mysema.query.types.FactoryExpression;
import com.mysema.query.types.FactoryExpressionUtils;
import com.mysema.query.types.QTuple;
/**
* Provides aggregated results as a list
*
* @author tiwe
*
* @param <K>
* @param <V>
*/
public class GroupByList<K, V> extends AbstractGroupByTransformer<K, List<V>> {
GroupByList(Expression<K> key, Expression<?>... expressions) {
super(key, expressions);
}
@Override
public List<V> transform(Projectable projectable) {
// create groups
FactoryExpression<Tuple> expr = FactoryExpressionUtils.wrap(new QTuple(expressions));
boolean hasGroups = false;
for (Expression<?> e : expr.getArgs()) {
hasGroups |= e instanceof GroupExpression;
}
if (hasGroups) {
expr = withoutGroupExpressions(expr);
}
final CloseableIterator<Tuple> iter = projectable.iterate(expr);
List<V> list = Lists.newArrayList();
GroupImpl group = null;
K groupId = null;
while (iter.hasNext()) {
Object[] row = iter.next().toArray();
if (group == null) {
group = new GroupImpl(groupExpressions, maps);
groupId = (K) row[0];
} else if (!Objects.equal(groupId, row[0])) {
list.add(transform(group));
group = new GroupImpl(groupExpressions, maps);
groupId = (K) row[0];
}
group.add(row);
}
if (group != null) {
list.add(transform(group));
}
iter.close();
return list;
}
protected V transform(Group group) {
return (V)group;
}
}