| /* |
| * 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 org.checkerframework.checker.nullness.compatqual.NullableDecl; |
| |
| /** |
| * A class to represent the set of edges connecting an (implicit) origin node to a target node. |
| * |
| * <p>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 <E> Edge parameter type |
| */ |
| final class EdgesConnecting<E> extends AbstractSet<E> { |
| |
| private final Map<?, E> nodeToOutEdge; |
| private final Object targetNode; |
| |
| EdgesConnecting(Map<?, E> nodeToEdgeMap, Object targetNode) { |
| this.nodeToOutEdge = checkNotNull(nodeToEdgeMap); |
| this.targetNode = checkNotNull(targetNode); |
| } |
| |
| @Override |
| public UnmodifiableIterator<E> iterator() { |
| E connectingEdge = getConnectingEdge(); |
| return (connectingEdge == null) |
| ? ImmutableSet.<E>of().iterator() |
| : Iterators.singletonIterator(connectingEdge); |
| } |
| |
| @Override |
| public int size() { |
| return getConnectingEdge() == null ? 0 : 1; |
| } |
| |
| @Override |
| public boolean contains(@NullableDecl Object edge) { |
| E connectingEdge = getConnectingEdge(); |
| return (connectingEdge != null && connectingEdge.equals(edge)); |
| } |
| |
| @NullableDecl |
| private E getConnectingEdge() { |
| return nodeToOutEdge.get(targetNode); |
| } |
| } |