| /* |
| * 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.calcite.rel; |
| |
| import org.apache.calcite.plan.RelOptCluster; |
| import org.apache.calcite.plan.RelTraitSet; |
| import org.apache.calcite.rel.metadata.RelMetadataQuery; |
| import org.apache.calcite.rel.type.RelDataType; |
| |
| import com.google.common.collect.ImmutableList; |
| |
| import java.util.List; |
| |
| /** |
| * Abstract base class for relational expressions with a single input. |
| * |
| * <p>It is not required that single-input relational expressions use this |
| * class as a base class. However, default implementations of methods make life |
| * easier. |
| */ |
| public abstract class SingleRel extends AbstractRelNode { |
| //~ Instance fields -------------------------------------------------------- |
| |
| protected RelNode input; |
| |
| //~ Constructors ----------------------------------------------------------- |
| |
| /** |
| * Creates a <code>SingleRel</code>. |
| * |
| * @param cluster Cluster this relational expression belongs to |
| * @param input Input relational expression |
| */ |
| protected SingleRel( |
| RelOptCluster cluster, |
| RelTraitSet traits, |
| RelNode input) { |
| super(cluster, traits); |
| this.input = input; |
| } |
| |
| //~ Methods ---------------------------------------------------------------- |
| |
| public RelNode getInput() { |
| return input; |
| } |
| |
| @Override public List<RelNode> getInputs() { |
| return ImmutableList.of(input); |
| } |
| |
| @Override public double estimateRowCount(RelMetadataQuery mq) { |
| // Not necessarily correct, but a better default than AbstractRelNode's 1.0 |
| return mq.getRowCount(input); |
| } |
| |
| @Override public void childrenAccept(RelVisitor visitor) { |
| visitor.visit(input, 0, this); |
| } |
| |
| public RelWriter explainTerms(RelWriter pw) { |
| return super.explainTerms(pw) |
| .input("input", getInput()); |
| } |
| |
| @Override public void replaceInput( |
| int ordinalInParent, |
| RelNode rel) { |
| assert ordinalInParent == 0; |
| this.input = rel; |
| } |
| |
| protected RelDataType deriveRowType() { |
| return input.getRowType(); |
| } |
| } |
| |
| // End SingleRel.java |