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 com.google.errorprone.annotations.CanIgnoreReturnValue; 20 import java.util.Iterator; 21 import java.util.Set; 22 import org.checkerframework.checker.nullness.qual.Nullable; 23 24 /** 25 * An interface for representing and manipulating an origin node's adjacent nodes and edge values in 26 * a {@link Graph}. 27 * 28 * @author James Sexton 29 * @param <N> Node parameter type 30 * @param <V> Value parameter type 31 */ 32 interface GraphConnections<N, V> { 33 adjacentNodes()34 Set<N> adjacentNodes(); 35 predecessors()36 Set<N> predecessors(); 37 successors()38 Set<N> successors(); 39 40 /** 41 * Returns an iterator over the incident edges. 42 * 43 * @param thisNode The node that this all of the connections in this class are connected to. 44 */ incidentEdgeIterator(N thisNode)45 Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode); 46 47 /** 48 * Returns the value associated with the edge connecting the origin node to {@code node}, or null 49 * if there is no such edge. 50 */ 51 @Nullable value(N node)52 V value(N node); 53 54 /** Remove {@code node} from the set of predecessors. */ removePredecessor(N node)55 void removePredecessor(N node); 56 57 /** 58 * Remove {@code node} from the set of successors. Returns the value previously associated with 59 * the edge connecting the two nodes. 60 */ 61 @CanIgnoreReturnValue removeSuccessor(N node)62 V removeSuccessor(N node); 63 64 /** 65 * Add {@code node} as a predecessor to the origin node. In the case of an undirected graph, it 66 * also becomes a successor. Associates {@code value} with the edge connecting the two nodes. 67 */ addPredecessor(N node, V value)68 void addPredecessor(N node, V value); 69 70 /** 71 * Add {@code node} as a successor to the origin node. In the case of an undirected graph, it also 72 * becomes a predecessor. Associates {@code value} with the edge connecting the two nodes. Returns 73 * the value previously associated with the edge connecting the two nodes. 74 */ 75 @CanIgnoreReturnValue addSuccessor(N node, V value)76 V addSuccessor(N node, V value); 77 } 78