Coverage Summary for Class: AbstractUndirectedNetworkConnections (com.google.common.graph)

1 /*
2  * Copyright (C) 2016 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.google.common.graph;
18 
19 import static com.google.common.base.Preconditions.checkNotNull;
20 import static com.google.common.base.Preconditions.checkState;
21 import static java.util.Objects.requireNonNull;
22 
23 import java.util.Collections;
24 import java.util.Map;
25 import java.util.Set;
26 import javax.annotation.CheckForNull;
27 
28 /**
29  * A base implementation of {@link NetworkConnections} for undirected networks.
30  *
31  * @author James Sexton
32  * @param <N> Node parameter type
33  * @param <E> Edge parameter type
34  */
35 @ElementTypesAreNonnullByDefault
36 abstract class AbstractUndirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {
37   /** Keys are edges incident to the origin node, values are the node at the other end. */
38   final Map<E, N> incidentEdgeMap;
39 
40   AbstractUndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
41     this.incidentEdgeMap = checkNotNull(incidentEdgeMap);
42   }
43 
44   @Override
45   public Set<N> predecessors() {
46     return adjacentNodes();
47   }
48 
49   @Override
50   public Set<N> successors() {
51     return adjacentNodes();
52   }
53 
54   @Override
55   public Set<E> incidentEdges() {
56     return Collections.unmodifiableSet(incidentEdgeMap.keySet());
57   }
58 
59   @Override
60   public Set<E> inEdges() {
61     return incidentEdges();
62   }
63 
64   @Override
65   public Set<E> outEdges() {
66     return incidentEdges();
67   }
68 
69   @Override
70   public N adjacentNode(E edge) {
71     // We're relying on callers to call this method only with an edge that's in the graph.
72     return requireNonNull(incidentEdgeMap.get(edge));
73   }
74 
75   @Override
76   @CheckForNull
77   public N removeInEdge(E edge, boolean isSelfLoop) {
78     if (!isSelfLoop) {
79       return removeOutEdge(edge);
80     }
81     return null;
82   }
83 
84   @Override
85   public N removeOutEdge(E edge) {
86     N previousNode = incidentEdgeMap.remove(edge);
87     // We're relying on callers to call this method only with an edge that's in the graph.
88     return requireNonNull(previousNode);
89   }
90 
91   @Override
92   public void addInEdge(E edge, N node, boolean isSelfLoop) {
93     if (!isSelfLoop) {
94       addOutEdge(edge, node);
95     }
96   }
97 
98   @Override
99   public void addOutEdge(E edge, N node) {
100     N previousNode = incidentEdgeMap.put(edge, node);
101     checkState(previousNode == null);
102   }
103 }