/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* 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 eu.stratosphere.compiler.plan;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import eu.stratosphere.compiler.dag.BinaryUnionNode;
import eu.stratosphere.compiler.dataproperties.GlobalProperties;
import eu.stratosphere.compiler.dataproperties.LocalProperties;
import eu.stratosphere.pact.runtime.task.DriverStrategy;
import eu.stratosphere.util.Visitor;
/**
* A union operation over multiple inputs (2 or more).
*/
public class NAryUnionPlanNode extends PlanNode {
private final List<Channel> inputs;
/**
* @param template
*/
public NAryUnionPlanNode(BinaryUnionNode template, List<Channel> inputs, GlobalProperties gProps) {
super(template, "Union", DriverStrategy.NONE);
this.inputs = inputs;
this.globalProps = gProps;
this.localProps = new LocalProperties();
}
@Override
public void accept(Visitor<PlanNode> visitor) {
visitor.preVisit(this);
for (Channel c : this.inputs) {
c.getSource().accept(visitor);
}
visitor.postVisit(this);
}
public List<Channel> getListOfInputs() {
return this.inputs;
}
@Override
public Iterator<Channel> getInputs() {
return Collections.unmodifiableList(this.inputs).iterator();
}
@Override
public Iterator<PlanNode> getPredecessors() {
final Iterator<Channel> channels = this.inputs.iterator();
return new Iterator<PlanNode>() {
@Override
public boolean hasNext() {
return channels.hasNext();
}
@Override
public PlanNode next() {
return channels.next().getSource();
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
}
@Override
public SourceAndDamReport hasDamOnPathDownTo(PlanNode source) {
// this node is used after the plan enumeration. consequently, this will never be invoked here
throw new UnsupportedOperationException();
}
}