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/*
 * 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.facebook.presto.jdbc.internal.guava.graph;

import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkArgument;
import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkNotNull;
import static com.facebook.presto.jdbc.internal.guava.graph.GraphConstants.DEFAULT_EDGE_COUNT;
import static com.facebook.presto.jdbc.internal.guava.graph.GraphConstants.DEFAULT_NODE_COUNT;
import static com.facebook.presto.jdbc.internal.guava.graph.GraphConstants.EDGE_NOT_IN_GRAPH;
import static com.facebook.presto.jdbc.internal.guava.graph.GraphConstants.NODE_NOT_IN_GRAPH;

import com.facebook.presto.jdbc.internal.guava.collect.ImmutableSet;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Configurable implementation of {@link Network} that supports the options supplied by {@link
 * NetworkBuilder}.
 *
 * 

This class maintains a map of nodes to {@link NetworkConnections}. This class also maintains a * map of edges to reference nodes. The reference node is defined to be the edge's source node on * directed graphs, and an arbitrary endpoint of the edge on undirected graphs. * *

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 * @author Joshua O'Madadhain * @author Omar Darwish * @param Node parameter type * @param Edge parameter type */ class ConfigurableNetwork extends AbstractNetwork { private final boolean isDirected; private final boolean allowsParallelEdges; private final boolean allowsSelfLoops; private final ElementOrder nodeOrder; private final ElementOrder edgeOrder; protected final MapIteratorCache> nodeConnections; // We could make this a Map>. It would make incidentNodes(edge) slightly // faster, but also make Networks consume 5 to 20+% (increasing with average degree) more memory. protected final MapIteratorCache edgeToReferenceNode; // referenceNode == source if directed /** Constructs a graph with the properties specified in {@code builder}. */ ConfigurableNetwork(NetworkBuilder builder) { this( builder, builder.nodeOrder.>createMap( builder.expectedNodeCount.or(DEFAULT_NODE_COUNT)), builder.edgeOrder.createMap(builder.expectedEdgeCount.or(DEFAULT_EDGE_COUNT))); } /** * Constructs a graph with the properties specified in {@code builder}, initialized with the given * node and edge maps. */ ConfigurableNetwork( NetworkBuilder builder, Map> nodeConnections, Map edgeToReferenceNode) { this.isDirected = builder.directed; this.allowsParallelEdges = builder.allowsParallelEdges; this.allowsSelfLoops = builder.allowsSelfLoops; this.nodeOrder = builder.nodeOrder.cast(); this.edgeOrder = builder.edgeOrder.cast(); // Prefer the heavier "MapRetrievalCache" for nodes if lookup is expensive. This optimizes // methods that access the same node(s) repeatedly, such as Graphs.removeEdgesConnecting(). this.nodeConnections = (nodeConnections instanceof TreeMap) ? new MapRetrievalCache>(nodeConnections) : new MapIteratorCache>(nodeConnections); this.edgeToReferenceNode = new MapIteratorCache<>(edgeToReferenceNode); } @Override public Set nodes() { return nodeConnections.unmodifiableKeySet(); } @Override public Set edges() { return edgeToReferenceNode.unmodifiableKeySet(); } @Override public boolean isDirected() { return isDirected; } @Override public boolean allowsParallelEdges() { return allowsParallelEdges; } @Override public boolean allowsSelfLoops() { return allowsSelfLoops; } @Override public ElementOrder nodeOrder() { return nodeOrder; } @Override public ElementOrder edgeOrder() { return edgeOrder; } @Override public Set incidentEdges(N node) { return checkedConnections(node).incidentEdges(); } @Override public EndpointPair incidentNodes(E edge) { N nodeU = checkedReferenceNode(edge); N nodeV = nodeConnections.get(nodeU).adjacentNode(edge); return EndpointPair.of(this, nodeU, nodeV); } @Override public Set adjacentNodes(N node) { return checkedConnections(node).adjacentNodes(); } @Override public Set edgesConnecting(N nodeU, N nodeV) { NetworkConnections connectionsU = checkedConnections(nodeU); if (!allowsSelfLoops && nodeU == nodeV) { // just an optimization, only check reference equality return ImmutableSet.of(); } checkArgument(containsNode(nodeV), NODE_NOT_IN_GRAPH, nodeV); return connectionsU.edgesConnecting(nodeV); } @Override public Set inEdges(N node) { return checkedConnections(node).inEdges(); } @Override public Set outEdges(N node) { return checkedConnections(node).outEdges(); } @Override public Set predecessors(N node) { return checkedConnections(node).predecessors(); } @Override public Set successors(N node) { return checkedConnections(node).successors(); } protected final NetworkConnections checkedConnections(N node) { NetworkConnections connections = nodeConnections.get(node); if (connections == null) { checkNotNull(node); throw new IllegalArgumentException(String.format(NODE_NOT_IN_GRAPH, node)); } return connections; } protected final N checkedReferenceNode(E edge) { N referenceNode = edgeToReferenceNode.get(edge); if (referenceNode == null) { checkNotNull(edge); throw new IllegalArgumentException(String.format(EDGE_NOT_IN_GRAPH, edge)); } return referenceNode; } protected final boolean containsNode(@Nullable N node) { return nodeConnections.containsKey(node); } protected final boolean containsEdge(@Nullable E edge) { return edgeToReferenceNode.containsKey(edge); } }





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