Class Node

1
2	/*
3	* Copyright (c) 2016 Vivid Solutions.
4	*
5	* All rights reserved. This program and the accompanying materials
6	* are made available under the terms of the Eclipse Public License 2.0
7	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
8	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
9	* and the Eclipse Distribution License is available at
10	*
11	* http://www.eclipse.org/org/documents/edl-v10.php.
12	*/
13
14
15	package org.locationtech.jts.planargraph;
16
17	import java.util.Collection;
18	import java.util.HashSet;
19	import java.util.List;
20	import java.util.Set;
21
22	import org.locationtech.jts.geom.Coordinate;
23
24	/**
25	* A node in a {@link PlanarGraph}is a location where 0 or more {@link Edge}s
26	* meet. A node is connected to each of its incident Edges via an outgoing
27	* DirectedEdge. Some clients using a <code>PlanarGraph</code> may want to
28	* subclass <code>Node</code> to add their own application-specific
29	* data and methods.
30	*
31	* @version 1.7
32	*/
33	public class Node
34	extends GraphComponent
35	{
36	/**
37	* Returns all Edges that connect the two nodes (which are assumed to be different).
38	*/
39	public static Collection getEdgesBetween(Node node0, Node node1)
40	{
41	List edges0 = DirectedEdge.toEdges(node0.getOutEdges().getEdges());
42	Set commonEdges = new HashSet(edges0);
43	List edges1 = DirectedEdge.toEdges(node1.getOutEdges().getEdges());
44	commonEdges.retainAll(edges1);
45	return commonEdges;
46	}
47
48	/** The location of this Node */
49	protected Coordinate pt;
50
51	/** The collection of DirectedEdges that leave this Node */
52	protected DirectedEdgeStar deStar;
53
54	/**
55	* Constructs a Node with the given location.
56	*/
57	public Node(Coordinate pt)
58	{
59	this(pt, new DirectedEdgeStar());
60	}
61
62	/**
63	* Constructs a Node with the given location and collection of outgoing DirectedEdges.
64	*/
65	public Node(Coordinate pt, DirectedEdgeStar deStar)
66	{
67	this.pt = pt;
68	this.deStar = deStar;
69	}
70
71	/**
72	* Returns the location of this Node.
73	*/
74	public Coordinate getCoordinate() { return pt; }
75
76	/**
77	* Adds an outgoing DirectedEdge to this Node.
78	*/
79	public void addOutEdge(DirectedEdge de)
80	{
81	deStar.add(de);
82	}
83
84	/**
85	* Returns the collection of DirectedEdges that leave this Node.
86	*/
87	public DirectedEdgeStar getOutEdges() { return deStar; }
88	/**
89	* Returns the number of edges around this Node.
90	*/
91	public int getDegree() { return deStar.getDegree(); }
92	/**
93	* Returns the zero-based index of the given Edge, after sorting in ascending order
94	* by angle with the positive x-axis.
95	*/
96	public int getIndex(Edge edge)
97	{
98	return deStar.getIndex(edge);
99	}
100
101	/**
102	* Removes a {@link DirectedEdge} incident on this node.
103	* Does not change the state of the directed edge.
104	*/
105	public void remove(DirectedEdge de)
106	{
107	deStar.remove(de);
108	}
109
110	/**
111	* Removes this node from its containing graph.
112	*/
113	void remove() {
114	pt = null;
115	}
116
117
118	/**
119	* Tests whether this node has been removed from its containing graph
120	*
121	* @return <code>true</code> if this node is removed
122	*/
123	public boolean isRemoved()
124	{
125	return pt == null;
126	}
127
128	}
129