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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.google.common.graph;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.graph.Graphs.checkNonNegative;
import static com.google.common.graph.Graphs.checkPositive;
import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.collect.Sets;
import com.google.common.collect.UnmodifiableIterator;
import com.google.common.math.IntMath;
import java.util.AbstractSet;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import org.checkerframework.checker.nullness.compatqual.NullableDecl;
/**
* 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> {
/** Keys are edges incoming to the origin node, values are the source node. */
protected final Map<E, N> inEdgeMap;
/** Keys are edges outgoing from the origin node, values are the target node. */
protected final Map<E, N> outEdgeMap;
private int selfLoopCount;
protected AbstractDirectedNetworkConnections(
Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
this.inEdgeMap = checkNotNull(inEdgeMap);
this.outEdgeMap = checkNotNull(outEdgeMap);
this.selfLoopCount = checkNonNegative(selfLoopCount);
checkState(selfLoopCount <= inEdgeMap.size() && selfLoopCount <= outEdgeMap.size());
}
@Override
public Set<N> adjacentNodes() {
return Sets.union(predecessors(), successors());
}
@Override
public Set<E> incidentEdges() {
return new AbstractSet<E>() {
@Override
public UnmodifiableIterator<E> iterator() {
Iterable<E> incidentEdges =
(selfLoopCount == 0)
? Iterables.concat(inEdgeMap.keySet(), outEdgeMap.keySet())
: Sets.union(inEdgeMap.keySet(), outEdgeMap.keySet());
return Iterators.unmodifiableIterator(incidentEdges.iterator());
}
@Override
public int size() {
return IntMath.saturatedAdd(inEdgeMap.size(), outEdgeMap.size() - selfLoopCount);
}
@Override
public boolean contains(@NullableDecl Object obj) {
return inEdgeMap.containsKey(obj) || outEdgeMap.containsKey(obj);
}
};
}
@Override
public Set<E> inEdges() {
return Collections.unmodifiableSet(inEdgeMap.keySet());
}
@Override
public Set<E> outEdges() {
return Collections.unmodifiableSet(outEdgeMap.keySet());
}
@Override
public N adjacentNode(E edge) {
// Since the reference node is defined to be 'source' for directed graphs,
// we can assume this edge lives in the set of outgoing edges.
return checkNotNull(outEdgeMap.get(edge));
}
@Override
public N removeInEdge(E edge, boolean isSelfLoop) {
if (isSelfLoop) {
checkNonNegative(--selfLoopCount);
}
N previousNode = inEdgeMap.remove(edge);
return checkNotNull(previousNode);
}
@Override
public N removeOutEdge(E edge) {
N previousNode = outEdgeMap.remove(edge);
return checkNotNull(previousNode);
}
@Override
public void addInEdge(E edge, N node, boolean isSelfLoop) {
if (isSelfLoop) {
checkPositive(++selfLoopCount);
}
N previousNode = inEdgeMap.put(edge, node);
checkState(previousNode == null);
}
@Override
public void addOutEdge(E edge, N node) {
N previousNode = outEdgeMap.put(edge, node);
checkState(previousNode == null);
}
}
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