*
 * <p>Time complexities for mutation methods are all O(1) except for {@code removeNode(N node)},
 * which is in O(d_node) where d_node is the degree of {@code node}.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 */
final class StandardMutableGraph<N> extends ForwardingGraph<N> implements MutableGraph<N> {
  private final MutableValueGraph<N, Presence> backingValueGraph;

import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * An interface for representing and manipulating an origin node's adjacent nodes and incident edges
 * in a {@link Network}.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @param <E> Edge parameter type
 */
interface NetworkConnections<N, E> {

  Set<N> adjacentNodes();

  Set<N> predecessors();

  Set<N> successors();

import java.util.Collections;
import java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A base implementation of {@link NetworkConnections} for undirected networks.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @param <E> Edge parameter type
 */
abstract class AbstractUndirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {

import java.util.Collections;
import java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A base implementation of {@link NetworkConnections} for directed networks.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @param <E> Edge parameter type
 */
abstract class AbstractDirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {

 */

package com.google.common.graph;

import java.util.Set;

/**
 * A non-public interface for the methods shared between {@link Graph} and {@link ValueGraph}.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 */
interface BaseGraph<N> extends ArchetypeGraph<N> {
  //
  // Graph-level accessors
  //

  /** Returns all edges in this graph. */
  Set<EndpointPair<N>> edges();

/**
 * A class to allow {@link Network} implementations to be backed by a provided delegate. This is not
 * currently planned to be released as a general-purpose forwarding class.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 */
abstract class ForwardingNetwork<N, E> extends AbstractNetwork<N, E> {

  abstract Network<N, E> delegate();

  @Override
  public Set<N> nodes() {

import java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * An implementation of {@link NetworkConnections} for directed networks with parallel edges.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @param <E> Edge parameter type
 */
final class DirectedMultiNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> {

  private DirectedMultiNetworkConnections(

 * map is immutable).
 *
 * <p>This class is tailored toward use cases in common.graph. It is *NOT* a general purpose map.
 *
 * @author James Sexton
 */
class MapIteratorCache<K, V> {
  private final Map<K, V> backingMap;

  /*
   * Per JDK: "the behavior of a map entry is undefined if the backing map has been modified after

/**
 * A subinterface of {@link Graph} which adds mutation methods. When mutation is not required, users
 * should prefer the {@link Graph} interface.
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @param <N> Node parameter type
 * @since 20.0
 */
public interface MutableGraph<N> extends Graph<N> {

  /**
   * Adds {@code node} if it is not already present.
   *

import java.util.Iterator;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A class to facilitate the set returned by {@link Graph#edges()}.
 *
 * @author James Sexton
 */
abstract class EndpointPairIterator<N> extends AbstractIterator<EndpointPair<N>> {
  private final BaseGraph<N> graph;
  private final Iterator<N> nodeIterator;