com.googlecode.blaisemath.graph.NodeInGraph Maven / Gradle / Ivy

Go to download
package com.googlecode.blaisemath.graph;

/*
 * #%L
 * BlaiseGraphTheory
 * --
 * Copyright (C) 2009 - 2019 Elisha Peterson
 * --
 * 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.
 * #L%
 */


import com.google.common.graph.Graph;
import org.checkerframework.checker.nullness.qual.Nullable;

import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Objects.requireNonNull;

/**
 * Data structure describing a node in a graph. This is a useful way to pass a reference to a graph's node, providing
 * the target object with access to both the node and the graph.
 *
 * @param  node type
 *
 * @author Elisha Peterson
 */
public final class NodeInGraph {

    private final E node;
    private final Graph graph;

    public NodeInGraph(E node, @Nullable Graph graph) {
        this.node = requireNonNull(node);
        this.graph = graph;
        checkArgument(graph == null || graph.nodes().contains(node));
    }

    public static  NodeInGraph create(E node) {
        return new NodeInGraph<>(node, null);
    }

    public E getNode() {
        return node;
    }

    public @Nullable Graph getGraph() {
        return graph;
    }

}