src/jsr166x/NavigableMap.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 */

package jsr166x;

import java.util.*;

/**
 * A {@link SortedMap} extended with methods returning key-value pairs
 * holding the closest matches for given search targets. Methods
 * <tt>lowerEntry</tt>, <tt>floorEntry</tt>, <tt>ceilingEntry</tt>,
 * and <tt>higherEntry</tt> return {@link Map.Entry} objects
 * associated with keys respectively less than, less than or equal,
 * greater than or equal, and greater than a given key, returning
 * <tt>null</tt> if there is no such key.  These methods are designed
 * for locating, not traversing entries. To traverse, use view
 * iterators and/or <tt>submap</tt>. This interface additionally
 * defines methods <tt>firstEntry</tt>, <tt>pollFirstEntry</tt>
 * <tt>lastEntry</tt>, and <tt>pollLastEntry</tt> that return and/or
 * remove the least and greatest mappings, if any exist, else
 * returning <tt>null</tt>.
 *
 * <p> Implementations of these methods are expected to return
 * <tt>Map.Entry</tt> pairs representing snapshots of mappings at the
 * time they were produced, and thus generally do <em>not</em> support
 * the optional <tt>Entry.setValue</tt> method. Note however that it
 * is possible to change mappings in the associated map using method
 * <tt>put</tt>.
 *
 * @author Doug Lea
 * @param <K> the type of keys maintained by this map
 * @param <V> the type of mapped values 
 */
public interface NavigableMap<K,V> extends SortedMap<K,V> {
    /**
     * Returns a key-value mapping associated with the least key
     * greater than or equal to the given key, or null if there is
     * no such entry. 
     * 
     * @param key the key.
     * @return an Entry associated with ceiling of given key, or null
     * if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> ceilingEntry(K key);

    /**
     * Returns a key-value mapping associated with the greatest
     * key strictly less than the given key, or null if there is no
     * such entry. 
     * 
     * @param key the key.
     * @return an Entry with greatest key less than the given
     * key, or null if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> lowerEntry(K key);

    /**
     * Returns a key-value mapping associated with the greatest
     * key less than or equal to the given key, or null if there is no
     * such entry. 
     * 
     * @param key the key.
     * @return an Entry associated with floor of given key, or null
     * if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> floorEntry(K key);

    /**
     * Returns a key-value mapping associated with the least
     * key strictly greater than the given key, or null if there is no
     * such entry. 
     * 
     * @param key the key.
     * @return an Entry with least key greater than the given key, or
     * null if there is no such Entry.
     * @throws ClassCastException if key cannot be compared with the keys
     *            currently in the map.
     * @throws NullPointerException if key is <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    public Map.Entry<K,V> higherEntry(K key);

    /**
     * Returns a key-value mapping associated with the least
     * key in this map, or null if the map is empty.
     * 
     * @return an Entry with least key, or null 
     * if the map is empty.
     */
    public Map.Entry<K,V> firstEntry();

    /**
     * Returns a key-value mapping associated with the greatest
     * key in this map, or null if the map is empty.
     * 
     * @return an Entry with greatest key, or null
     * if the map is empty.
     */
    public Map.Entry<K,V> lastEntry();

    /**
     * Removes and returns a key-value mapping associated with
     * the least key in this map, or null if the map is empty.
     * 
     * @return the removed first entry of this map, or null
     * if the map is empty.
     */
    public Map.Entry<K,V> pollFirstEntry();

    /**
     * Removes and returns a key-value mapping associated with
     * the greatest key in this map, or null if the map is empty.
     * 
     * @return the removed last entry of this map, or null
     * if the map is empty.
     */
    public Map.Entry<K,V> pollLastEntry();

    /**
     * Returns a view of the portion of this map whose keys range from
     * <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.  (If
     * <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned sorted map
     * is empty.)  The returned sorted map is backed by this map, so changes
     * in the returned sorted map are reflected in this map, and vice-versa.

     * @param fromKey low endpoint (inclusive) of the subMap.
     * @param toKey high endpoint (exclusive) of the subMap.
     *
     * @return a view of the portion of this map whose keys range from
     * <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
     *
     * @throws ClassCastException if <tt>fromKey</tt> and
     * <tt>toKey</tt> cannot be compared to one another using this
     * map's comparator (or, if the map has no comparator, using
     * natural ordering).
     * @throws IllegalArgumentException if <tt>fromKey</tt> is greater
     * than <tt>toKey</tt>.
     * @throws NullPointerException if <tt>fromKey</tt> or
     * <tt>toKey</tt> is <tt>null</tt> and this map does not support
     * <tt>null</tt> keys.
     */
    public NavigableMap<K,V> subMap(K fromKey, K toKey);

    /**
     * Returns a view of the portion of this map whose keys are strictly less
     * than <tt>toKey</tt>.  The returned sorted map is backed by this map, so
     * changes in the returned sorted map are reflected in this map, and
     * vice-versa.  
     * @param toKey high endpoint (exclusive) of the headMap.
     * @return a view of the portion of this map whose keys are strictly
     *                less than <tt>toKey</tt>.
     *
     * @throws ClassCastException if <tt>toKey</tt> is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
     * @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
     * and this map does not support <tt>null</tt> keys.
     */
    public NavigableMap<K,V> headMap(K toKey);

    /**
     * Returns a view of the portion of this map whose keys are
     * greater than or equal to <tt>fromKey</tt>.  The returned sorted
     * map is backed by this map, so changes in the returned sorted
     * map are reflected in this map, and vice-versa.
     * @param fromKey low endpoint (inclusive) of the tailMap.
     * @return a view of the portion of this map whose keys are greater
     *                than or equal to <tt>fromKey</tt>.
     * @throws ClassCastException if <tt>fromKey</tt> is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
     * @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
     * and this map does not support <tt>null</tt> keys.
     */
    public NavigableMap<K,V>  tailMap(K fromKey);
}
Revision:	1.1
Committed:	Mon Sep 6 17:01:54 2004 UTC (19 years, 8 months ago) by dl
Branch:	MAIN
Log Message:	Add Navigable interfaces for concurrent skip list classes; adjust accordingly
#	Content
1	/*
2	* Written by Doug Lea with assistance from members of JCP JSR-166
3	* Expert Group and released to the public domain, as explained at
4	* http://creativecommons.org/licenses/publicdomain
5	*/
6
7	package jsr166x;
8
9	import java.util.*;
10
11	/**
12	* A {@link SortedMap} extended with methods returning key-value pairs
13	* holding the closest matches for given search targets. Methods
14	* <tt>lowerEntry</tt>, <tt>floorEntry</tt>, <tt>ceilingEntry</tt>,
15	* and <tt>higherEntry</tt> return {@link Map.Entry} objects
16	* associated with keys respectively less than, less than or equal,
17	* greater than or equal, and greater than a given key, returning
18	* <tt>null</tt> if there is no such key. These methods are designed
19	* for locating, not traversing entries. To traverse, use view
20	* iterators and/or <tt>submap</tt>. This interface additionally
21	* defines methods <tt>firstEntry</tt>, <tt>pollFirstEntry</tt>
22	* <tt>lastEntry</tt>, and <tt>pollLastEntry</tt> that return and/or
23	* remove the least and greatest mappings, if any exist, else
24	* returning <tt>null</tt>.
25	*
26	* <p> Implementations of these methods are expected to return
27	* <tt>Map.Entry</tt> pairs representing snapshots of mappings at the
28	* time they were produced, and thus generally do <em>not</em> support
29	* the optional <tt>Entry.setValue</tt> method. Note however that it
30	* is possible to change mappings in the associated map using method
31	* <tt>put</tt>.
32	*
33	* @author Doug Lea
34	* @param <K> the type of keys maintained by this map
35	* @param <V> the type of mapped values
36	*/
37	public interface NavigableMap<K,V> extends SortedMap<K,V> {
38	/**
39	* Returns a key-value mapping associated with the least key
40	* greater than or equal to the given key, or null if there is
41	* no such entry.
42	*
43	* @param key the key.
44	* @return an Entry associated with ceiling of given key, or null
45	* if there is no such Entry.
46	* @throws ClassCastException if key cannot be compared with the keys
47	* currently in the map.
48	* @throws NullPointerException if key is <tt>null</tt> and this map
49	* does not support <tt>null</tt> keys.
50	*/
51	public Map.Entry<K,V> ceilingEntry(K key);
52
53	/**
54	* Returns a key-value mapping associated with the greatest
55	* key strictly less than the given key, or null if there is no
56	* such entry.
57	*
58	* @param key the key.
59	* @return an Entry with greatest key less than the given
60	* key, or null if there is no such Entry.
61	* @throws ClassCastException if key cannot be compared with the keys
62	* currently in the map.
63	* @throws NullPointerException if key is <tt>null</tt> and this map
64	* does not support <tt>null</tt> keys.
65	*/
66	public Map.Entry<K,V> lowerEntry(K key);
67
68	/**
69	* Returns a key-value mapping associated with the greatest
70	* key less than or equal to the given key, or null if there is no
71	* such entry.
72	*
73	* @param key the key.
74	* @return an Entry associated with floor of given key, or null
75	* if there is no such Entry.
76	* @throws ClassCastException if key cannot be compared with the keys
77	* currently in the map.
78	* @throws NullPointerException if key is <tt>null</tt> and this map
79	* does not support <tt>null</tt> keys.
80	*/
81	public Map.Entry<K,V> floorEntry(K key);
82
83	/**
84	* Returns a key-value mapping associated with the least
85	* key strictly greater than the given key, or null if there is no
86	* such entry.
87	*
88	* @param key the key.
89	* @return an Entry with least key greater than the given key, or
90	* null if there is no such Entry.
91	* @throws ClassCastException if key cannot be compared with the keys
92	* currently in the map.
93	* @throws NullPointerException if key is <tt>null</tt> and this map
94	* does not support <tt>null</tt> keys.
95	*/
96	public Map.Entry<K,V> higherEntry(K key);
97
98	/**
99	* Returns a key-value mapping associated with the least
100	* key in this map, or null if the map is empty.
101	*
102	* @return an Entry with least key, or null
103	* if the map is empty.
104	*/
105	public Map.Entry<K,V> firstEntry();
106
107	/**
108	* Returns a key-value mapping associated with the greatest
109	* key in this map, or null if the map is empty.
110	*
111	* @return an Entry with greatest key, or null
112	* if the map is empty.
113	*/
114	public Map.Entry<K,V> lastEntry();
115
116	/**
117	* Removes and returns a key-value mapping associated with
118	* the least key in this map, or null if the map is empty.
119	*
120	* @return the removed first entry of this map, or null
121	* if the map is empty.
122	*/
123	public Map.Entry<K,V> pollFirstEntry();
124
125	/**
126	* Removes and returns a key-value mapping associated with
127	* the greatest key in this map, or null if the map is empty.
128	*
129	* @return the removed last entry of this map, or null
130	* if the map is empty.
131	*/
132	public Map.Entry<K,V> pollLastEntry();
133
134	/**
135	* Returns a view of the portion of this map whose keys range from
136	* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive. (If
137	* <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned sorted map
138	* is empty.) The returned sorted map is backed by this map, so changes
139	* in the returned sorted map are reflected in this map, and vice-versa.
140
141	* @param fromKey low endpoint (inclusive) of the subMap.
142	* @param toKey high endpoint (exclusive) of the subMap.
143	*
144	* @return a view of the portion of this map whose keys range from
145	* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
146	*
147	* @throws ClassCastException if <tt>fromKey</tt> and
148	* <tt>toKey</tt> cannot be compared to one another using this
149	* map's comparator (or, if the map has no comparator, using
150	* natural ordering).
151	* @throws IllegalArgumentException if <tt>fromKey</tt> is greater
152	* than <tt>toKey</tt>.
153	* @throws NullPointerException if <tt>fromKey</tt> or
154	* <tt>toKey</tt> is <tt>null</tt> and this map does not support
155	* <tt>null</tt> keys.
156	*/
157	public NavigableMap<K,V> subMap(K fromKey, K toKey);
158
159	/**
160	* Returns a view of the portion of this map whose keys are strictly less
161	* than <tt>toKey</tt>. The returned sorted map is backed by this map, so
162	* changes in the returned sorted map are reflected in this map, and
163	* vice-versa.
164	* @param toKey high endpoint (exclusive) of the headMap.
165	* @return a view of the portion of this map whose keys are strictly
166	* less than <tt>toKey</tt>.
167	*
168	* @throws ClassCastException if <tt>toKey</tt> is not compatible
169	* with this map's comparator (or, if the map has no comparator,
170	* if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
171	* @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
172	* and this map does not support <tt>null</tt> keys.
173	*/
174	public NavigableMap<K,V> headMap(K toKey);
175
176	/**
177	* Returns a view of the portion of this map whose keys are
178	* greater than or equal to <tt>fromKey</tt>. The returned sorted
179	* map is backed by this map, so changes in the returned sorted
180	* map are reflected in this map, and vice-versa.
181	* @param fromKey low endpoint (inclusive) of the tailMap.
182	* @return a view of the portion of this map whose keys are greater
183	* than or equal to <tt>fromKey</tt>.
184	* @throws ClassCastException if <tt>fromKey</tt> is not compatible
185	* with this map's comparator (or, if the map has no comparator,
186	* if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
187	* @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
188	* and this map does not support <tt>null</tt> keys.
189	*/
190	public NavigableMap<K,V> tailMap(K fromKey);
191	}