171 lines
6.8 KiB
Java
171 lines
6.8 KiB
Java
/* SortedMap.java -- A map that makes guarantees about the order of its keys
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Copyright (C) 1998, 2001 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.util;
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/**
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* A map which guarantees its key's iteration order. The entries in the
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* map are related by the <i>natural ordering</i> of the keys if they
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* are Comparable, or by the provided Comparator. Additional operations
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* take advantage of the sorted nature of the map.
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* <p>
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*
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* All keys entered in the map must be mutually comparable; in other words,
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* <code>k1.compareTo(k2)</code> or <code>comparator.compare(k1, k2)</code>
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* must not throw a ClassCastException. The ordering must be <i>consistent
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* with equals</i> (see {@link Comparator} for this definition), if the
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* map is to obey the general contract of the Map interface. If not,
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* the results are well-defined, but probably not what you wanted.
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* <p>
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*
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* It is recommended that all implementing classes provide four constructors:
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* 1) one that takes no arguments and builds an empty map sorted by natural
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* order of the keys; 2) one that takes a Comparator for the sorting order;
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* 3) one that takes a Map and sorts according to the natural order of its
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* keys; and 4) one that takes a SortedMap and sorts by the same comparator.
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* Unfortunately, the Java language does not provide a way to enforce this.
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*
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* @author Original author unknown
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* @author Eric Blake <ebb9@email.byu.edu>
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* @see Map
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* @see TreeMap
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* @see SortedSet
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* @see Comparable
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* @see Comparator
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* @see Collection
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* @see ClassCastException
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* @since 1.2
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* @status updated to 1.4
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*/
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public interface SortedMap extends Map
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{
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/**
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* Returns the comparator used in sorting this map, or null if it is
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* the keys' natural ordering.
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*
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* @return the sorting comparator
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*/
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Comparator comparator();
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/**
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* Returns the first (lowest sorted) key in the map.
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*
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* @return the first key
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*/
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Object firstKey();
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/**
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* Returns a view of the portion of the map strictly less than toKey. The
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* view is backed by this map, so changes in one show up in the other.
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* The submap supports all optional operations of the original.
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* <p>
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*
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* The returned map throws an IllegalArgumentException any time a key is
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* used which is out of the range of toKey. Note that the endpoint is not
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* included; if you want the endpoint, pass the successor object in to
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* toKey. For example, for Strings, you can request
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* <code>headMap(limit + "\0")</code>.
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*
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* @param toKey the exclusive upper range of the submap
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* @return the submap
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* @throws ClassCastException if toKey is not comparable to the map contents
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* @throws IllegalArgumentException if this is a subMap, and toKey is out
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* of range
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* @throws NullPointerException if toKey is null but the map does not allow
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* null keys
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*/
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SortedMap headMap(Object toKey);
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/**
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* Returns the last (highest sorted) key in the map.
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*
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* @return the last key
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*/
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Object lastKey();
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/**
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* Returns a view of the portion of the map greater than or equal to
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* fromKey, and strictly less than toKey. The view is backed by this map,
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* so changes in one show up in the other. The submap supports all
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* optional operations of the original.
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* <p>
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*
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* The returned map throws an IllegalArgumentException any time a key is
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* used which is out of the range of fromKey and toKey. Note that the
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* lower endpoint is included, but the upper is not; if you want to
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* change the inclusion or exclusion of an endpoint, pass the successor
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* object in instead. For example, for Strings, you can request
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* <code>subMap(lowlimit + "\0", highlimit + "\0")</code> to reverse
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* the inclusiveness of both endpoints.
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*
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* @param fromKey the inclusive lower range of the submap
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* @param toKey the exclusive upper range of the submap
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* @return the submap
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* @throws ClassCastException if fromKey or toKey is not comparable to
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* the map contents
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* @throws IllegalArgumentException if this is a subMap, and fromKey or
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* toKey is out of range
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* @throws NullPointerException if fromKey or toKey is null but the map
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* does not allow null keys
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*/
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SortedMap subMap(Object fromKey, Object toKey);
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/**
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* Returns a view of the portion of the map greater than or equal to
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* fromKey. The view is backed by this map, so changes in one show up
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* in the other. The submap supports all optional operations of the original.
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* <p>
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*
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* The returned map throws an IllegalArgumentException any time a key is
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* used which is out of the range of fromKey. Note that the endpoint is
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* included; if you do not want the endpoint, pass the successor object in
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* to fromKey. For example, for Strings, you can request
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* <code>tailMap(limit + "\0")</code>.
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*
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* @param fromKey the inclusive lower range of the submap
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* @return the submap
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* @throws ClassCastException if fromKey is not comparable to the map
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* contents
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* @throws IllegalArgumentException if this is a subMap, and fromKey is out
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* of range
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* @throws NullPointerException if fromKey is null but the map does not allow
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* null keys
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*/
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SortedMap tailMap(Object fromKey);
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}
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