Class GraphComponent

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	package org.locationtech.jts.planargraph;
14
15	import java.util.Iterator;
16
17	/**
18	* The base class for all graph component classes.
19	* Maintains flags of use in generic graph algorithms.
20	* Provides two flags:
21	* <ul>
22	* <li><b>marked</b> - typically this is used to indicate a state that persists
23	* for the course of the graph's lifetime. For instance, it can be
24	* used to indicate that a component has been logically deleted from the graph.
25	* <li><b>visited</b> - this is used to indicate that a component has been processed
26	* or visited by an single graph algorithm. For instance, a breadth-first traversal of the
27	* graph might use this to indicate that a node has already been traversed.
28	* The visited flag may be set and cleared many times during the lifetime of a graph.
29	* </ul>
30	*
31	* <p>
32	* Graph components support storing user context data. This will typically be
33	* used by client algorithms which use planar graphs.
34	*
35	* @version 1.7
36	*/
37	public abstract class GraphComponent
38	{
39	/**
40	* Sets the Visited state for all {@link GraphComponent}s in an {@link Iterator}
41	*
42	* @param i the Iterator to scan
43	* @param visited the state to set the visited flag to
44	*/
45	public static void setVisited(Iterator i, boolean visited)
46	{
47	while (i.hasNext()) {
48	GraphComponent comp = (GraphComponent) i.next();
49	comp.setVisited(visited);
50	}
51	}
52
53	/**
54	* Sets the Marked state for all {@link GraphComponent}s in an {@link Iterator}
55	*
56	* @param i the Iterator to scan
57	* @param marked the state to set the Marked flag to
58	*/
59	public static void setMarked(Iterator i, boolean marked)
60	{
61	while (i.hasNext()) {
62	GraphComponent comp = (GraphComponent) i.next();
63	comp.setMarked(marked);
64	}
65	}
66
67	/**
68	* Finds the first {@link GraphComponent} in a {@link Iterator} set
69	* which has the specified visited state.
70	*
71	* @param i an Iterator of GraphComponents
72	* @param visitedState the visited state to test
73	* @return the first component found, or <code>null</code> if none found
74	*/
75	public static GraphComponent getComponentWithVisitedState(Iterator i, boolean visitedState)
76	{
77	while (i.hasNext()) {
78	GraphComponent comp = (GraphComponent) i.next();
79	if (comp.isVisited() == visitedState)
80	return comp;
81	}
82	return null;
83	}
84
85	protected boolean isMarked = false;
86	protected boolean isVisited = false;
87	private Object data;
88
89	public GraphComponent() {
90	}
91
92	/**
93	* Tests if a component has been visited during the course of a graph algorithm
94	* @return <code>true</code> if the component has been visited
95	*/
96	public boolean isVisited() { return isVisited; }
97
98	/**
99	* Sets the visited flag for this component.
100	* @param isVisited the desired value of the visited flag
101	*/
102	public void setVisited(boolean isVisited) { this.isVisited = isVisited; }
103
104	/**
105	* Tests if a component has been marked at some point during the processing
106	* involving this graph.
107	* @return <code>true</code> if the component has been marked
108	*/
109	public boolean isMarked() { return isMarked; }
110
111	/**
112	* Sets the marked flag for this component.
113	* @param isMarked the desired value of the marked flag
114	*/
115	public void setMarked(boolean isMarked) { this.isMarked = isMarked; }
116
117	/**
118	* Sets the user-defined data for this component.
119	*
120	* @param data an Object containing user-defined data
121	*/
122	public void setContext(Object data) { this.data = data; }
123
124	/**
125	* Gets the user-defined data for this component.
126	*
127	* @return the user-defined data
128	*/
129	public Object getContext() { return data; }
130
131	/**
132	* Sets the user-defined data for this component.
133	*
134	* @param data an Object containing user-defined data
135	*/
136	public void setData(Object data) { this.data = data; }
137
138	/**
139	* Gets the user-defined data for this component.
140	*
141	* @return the user-defined data
142	*/
143	public Object getData() { return data; }
144
145	/**
146	* Tests whether this component has been removed from its containing graph
147	*
148	* @return <code>true</code> if this component is removed
149	*/
150	public abstract boolean isRemoved();
151	}
152