logical/src/main/java/org/apache/drill/common/graph/Graph.java

/*
 * 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.common.graph;

import java.util.Collection;
import java.util.List;

import org.apache.drill.common.logical.UnexpectedOperatorType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


public class Graph<G extends GraphValue<G>, R extends G, T extends G> {

  static final Logger logger = LoggerFactory.getLogger(Graph.class);

  private AdjacencyList<G> adjList;
  private final List<R> roots;
  private final List<T> leaves;

  public Graph(List<G> operators, Class<R> root, Class<T> leaf) {
    adjList = AdjacencyList.newInstance(operators);
    roots = checkOperatorType(adjList.getRootNodes(), root, String.format("Root nodes must be a subclass of %s.", root.getSimpleName()));
    leaves = checkOperatorType(adjList.getLeafNodes(), leaf, String.format("Leaf nodes must be a subclass of %s.", leaf.getSimpleName()));
  }

  @SuppressWarnings("unchecked")
  private <O extends G> List<O> checkOperatorType(Collection<G> ops, Class<O> classIdentifier, String error){
    for(G o : ops){
      if(!classIdentifier.isAssignableFrom(o.getClass())){
        throw new UnexpectedOperatorType(o, error);
      }
    }
    return (List<O>) ops;
  }

  public AdjacencyList<G> getAdjList() {
    return adjList;
  }

  public Collection<R> getRoots() {
    return roots;
  }

  public Collection<T> getLeaves() {
    return leaves;
  }

  public static <G extends GraphValue<G>, R extends G, T extends G> Graph<G, R, T> newGraph(List<G> operators, Class<R> root, Class<T> leaf){
    return new Graph<G, R, T>(operators, root, leaf);
  }

}