/*
 * Copyright (C) 2016 The Guava Authors
 *
 * 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.
 */

package com.google.common.graph;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.graph.GraphConstants.DEFAULT_NODE_COUNT;
import static com.google.common.graph.Graphs.checkNonNegative;

import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import org.checkerframework.checker.nullness.qual.Nullable;

Configurable implementation of ValueGraph that supports the options supplied by AbstractGraphBuilder.

This class maintains a map of nodes to GraphConnections.

Collection-returning accessors return unmodifiable views: the view returned will reflect changes to the graph (if the graph is mutable) but may not be modified by the user.

The time complexity of all collection-returning accessors is O(1), since views are returned.

Author:James Sexton, Joshua O'Madadhain, Omar Darwish
Type parameters:
  • <N> – Node parameter type
  • <V> – Value parameter type
/** * Configurable implementation of {@link ValueGraph} that supports the options supplied by {@link * AbstractGraphBuilder}. * * <p>This class maintains a map of nodes to {@link GraphConnections}. * * <p>Collection-returning accessors return unmodifiable views: the view returned will reflect * changes to the graph (if the graph is mutable) but may not be modified by the user. * * <p>The time complexity of all collection-returning accessors is O(1), since views are returned. * * @author James Sexton * @author Joshua O'Madadhain * @author Omar Darwish * @param <N> Node parameter type * @param <V> Value parameter type */
class ConfigurableValueGraph<N, V> extends AbstractValueGraph<N, V> { private final boolean isDirected; private final boolean allowsSelfLoops; private final ElementOrder<N> nodeOrder; protected final MapIteratorCache<N, GraphConnections<N, V>> nodeConnections; protected long edgeCount; // must be updated when edges are added or removed
Constructs a graph with the properties specified in builder.
/** Constructs a graph with the properties specified in {@code builder}. */
ConfigurableValueGraph(AbstractGraphBuilder<? super N> builder) { this( builder, builder.nodeOrder.<N, GraphConnections<N, V>>createMap( builder.expectedNodeCount.or(DEFAULT_NODE_COUNT)), 0L); }
Constructs a graph with the properties specified in builder, initialized with the given node map.
/** * Constructs a graph with the properties specified in {@code builder}, initialized with the given * node map. */
ConfigurableValueGraph( AbstractGraphBuilder<? super N> builder, Map<N, GraphConnections<N, V>> nodeConnections, long edgeCount) { this.isDirected = builder.directed; this.allowsSelfLoops = builder.allowsSelfLoops; this.nodeOrder = builder.nodeOrder.cast(); // Prefer the heavier "MapRetrievalCache" for nodes if lookup is expensive. this.nodeConnections = (nodeConnections instanceof TreeMap) ? new MapRetrievalCache<N, GraphConnections<N, V>>(nodeConnections) : new MapIteratorCache<N, GraphConnections<N, V>>(nodeConnections); this.edgeCount = checkNonNegative(edgeCount); } @Override public Set<N> nodes() { return nodeConnections.unmodifiableKeySet(); } @Override public boolean isDirected() { return isDirected; } @Override public boolean allowsSelfLoops() { return allowsSelfLoops; } @Override public ElementOrder<N> nodeOrder() { return nodeOrder; } @Override public Set<N> adjacentNodes(N node) { return checkedConnections(node).adjacentNodes(); } @Override public Set<N> predecessors(N node) { return checkedConnections(node).predecessors(); } @Override public Set<N> successors(N node) { return checkedConnections(node).successors(); } @Override public boolean hasEdgeConnecting(N nodeU, N nodeV) { checkNotNull(nodeU); checkNotNull(nodeV); GraphConnections<N, V> connectionsU = nodeConnections.get(nodeU); return (connectionsU != null) && connectionsU.successors().contains(nodeV); } @Override public @Nullable V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue) { checkNotNull(nodeU); checkNotNull(nodeV); GraphConnections<N, V> connectionsU = nodeConnections.get(nodeU); V value = (connectionsU == null) ? null : connectionsU.value(nodeV); return value == null ? defaultValue : value; } @Override protected long edgeCount() { return edgeCount; } protected final GraphConnections<N, V> checkedConnections(N node) { GraphConnections<N, V> connections = nodeConnections.get(node); if (connections == null) { checkNotNull(node); throw new IllegalArgumentException("Node " + node + " is not an element of this graph."); } return connections; } protected final boolean containsNode(@Nullable N node) { return nodeConnections.containsKey(node); } }