001/*
002 * Copyright (C) 2016 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.graph;
018
019import org.jspecify.annotations.Nullable;
020
021/**
022 * This class provides a skeletal implementation of {@link Graph}. It is recommended to extend this
023 * class rather than implement {@link Graph} directly.
024 *
025 * @author James Sexton
026 * @param <N> Node parameter type
027 * @since 20.0
028 */
029public abstract class AbstractGraph<N> extends AbstractBaseGraph<N> implements Graph<N> {
030  /** Constructor for use by subclasses. */
031  protected AbstractGraph() {}
032
033  @Override
034  public final boolean equals(@Nullable Object obj) {
035    if (obj == this) {
036      return true;
037    }
038    if (!(obj instanceof Graph)) {
039      return false;
040    }
041    Graph<?> other = (Graph<?>) obj;
042
043    return isDirected() == other.isDirected()
044        && nodes().equals(other.nodes())
045        && edges().equals(other.edges());
046  }
047
048  @Override
049  public final int hashCode() {
050    return edges().hashCode();
051  }
052
053  /** Returns a string representation of this graph. */
054  @Override
055  public String toString() {
056    return "isDirected: "
057        + isDirected()
058        + ", allowsSelfLoops: "
059        + allowsSelfLoops()
060        + ", nodes: "
061        + nodes()
062        + ", edges: "
063        + edges();
064  }
065}