| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.drill.exec.physical.base; |
| |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import com.fasterxml.jackson.annotation.JsonIgnore; |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.Iterators; |
| |
| /** |
| * Describes an operator that expects a single child operator as its input. |
| */ |
| public abstract class AbstractSingle extends AbstractBase { |
| static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(AbstractSingle.class); |
| |
| protected final PhysicalOperator child; |
| |
| public AbstractSingle(PhysicalOperator child) { |
| super(); |
| this.child = child; |
| } |
| |
| @Override |
| public Iterator<PhysicalOperator> iterator() { |
| return Iterators.singletonIterator(child); |
| } |
| |
| public PhysicalOperator getChild(){ |
| return child; |
| } |
| |
| @Override |
| @JsonIgnore |
| public final PhysicalOperator getNewWithChildren(List<PhysicalOperator> children) { |
| Preconditions.checkArgument(children.size() == 1); |
| return getNewWithChild(children.iterator().next()); |
| } |
| |
| protected abstract PhysicalOperator getNewWithChild(PhysicalOperator child); |
| |
| |
| |
| |
| } |