com.google.common.graph.EdgesConnecting Maven / Gradle / Ivy
/*
* 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 com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterators;
import com.google.common.collect.UnmodifiableIterator;
import java.util.AbstractSet;
import java.util.Map;
import javax.annotation.CheckForNull;
/**
* A class to represent the set of edges connecting an (implicit) origin node to a target node.
*
* The {@link #nodeToOutEdge} map means this class only works on networks without parallel edges.
* See {@link MultiEdgesConnecting} for a class that works with parallel edges.
*
* @author James Sexton
* @param Edge parameter type
*/
@ElementTypesAreNonnullByDefault
final class EdgesConnecting extends AbstractSet {
private final Map nodeToOutEdge;
private final Object targetNode;
EdgesConnecting(Map nodeToEdgeMap, Object targetNode) {
this.nodeToOutEdge = checkNotNull(nodeToEdgeMap);
this.targetNode = checkNotNull(targetNode);
}
@Override
public UnmodifiableIterator iterator() {
E connectingEdge = getConnectingEdge();
return (connectingEdge == null)
? ImmutableSet.of().iterator()
: Iterators.singletonIterator(connectingEdge);
}
@Override
public int size() {
return getConnectingEdge() == null ? 0 : 1;
}
@Override
public boolean contains(@CheckForNull Object edge) {
E connectingEdge = getConnectingEdge();
return (connectingEdge != null && connectingEdge.equals(edge));
}
@CheckForNull
private E getConnectingEdge() {
return nodeToOutEdge.get(targetNode);
}
}