org.drools.core.base.accumulators.CollectListAccumulateFunction Maven / Gradle / Ivy
/*
* Copyright 2010 Red Hat, Inc. and/or its affiliates.
*
* 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.drools.core.base.accumulators;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* An implementation of an accumulator capable of collecting lists of values.
* This is similar to the "collect" CE, but allows us to collect any value, not
* only facts.
*
* Example:
*
* rule "List employee names"
* when
* $names : List() from accumulate(
* Employee( $n : firstName, $l : lastName ),
* collectList( $n + " " + $l ) )
* then
* // do something
* end
*
*
* The list accepts duplications and the order of the elements in the list is not
* guaranteed.
*/
public class CollectListAccumulateFunction extends AbstractAccumulateFunction {
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
// functions are stateless, so nothing to serialize
}
public void writeExternal(ObjectOutput out) throws IOException {
// functions are stateless, so nothing to serialize
}
public static class CollectListData
implements
Externalizable {
public List< Object > list = new ArrayList