immutablesortedmap.java

pastry的java实现的2.0b版

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"FreePastry" Peer-to-Peer Application Development Substrate 

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package rice.p2p.util;

import java.io.*;
import java.util.*;

/**
 * @(#) ImmutableSortedMap.java Class which is an implementation of a sorted map
 * which wraps and protects an internal sorted map. Any attempts to modify the
 * underlying map will result in a UnsupportedOperationException.
 *
 * @version $Id: ImmutableSortedMap.java 2302 2005-03-11 00:58:26Z jeffh $
 * @author Alan Mislove
 */
public class ImmutableSortedMap implements SortedMap, Serializable {

  // the internal map
  /**
   * DESCRIBE THE FIELD
   */
  protected SortedMap map;

  /**
   * Constructor which takes an existing map
   *
   * @param map the existing map
   */
  public ImmutableSortedMap(SortedMap map) {
    this.map = map;
  }

  /**
   * Returns <tt>true</tt> if this map contains no key-value mappings.
   *
   * @return <tt>true</tt> if this map contains no key-value mappings.
   */
  public boolean isEmpty() {
    return map.isEmpty();
  }

  /**
   * Returns the value to which this map maps the specified key. Returns <tt>
   * null</tt> if the map contains no mapping for this key.
   *
   * @param key key whose associated value is to be returned.
   * @return the value to which this map maps the specified key, or <tt>null
   *      </tt> if the map contains no mapping for this key.
   */
  public Object get(Object key) {
    return map.get(key);
  }

  /**
   * Returns the comparator associated with this sorted map, or <tt>null</tt> if
   * it uses its keys' natural ordering.
   *
   * @return the comparator associated with this sorted map, or <tt>null</tt> if
   *      it uses its keys' natural ordering.
   */
  public Comparator comparator() {
    return map.comparator();
  }

  /**
   * Returns a view of the portion of this sorted map whose keys range from <tt>
   * fromKey</tt> , inclusive, to <tt>toKey</tt> , exclusive.
   *
   * @param fromKey low endpoint (inclusive) of the subMap.
   * @param toKey high endpoint (exclusive) of the subMap.
   * @return a view of the specified range within this sorted map.
   */
  public SortedMap subMap(Object fromKey, Object toKey) {
    return new ImmutableSortedMap(map.subMap(fromKey, toKey));
  }

  /**
   * Returns a view of the portion of this sorted map whose keys are strictly
   * less than toKey.
   *
   * @param toKey high endpoint (exclusive) of the subMap.
   * @return a view of the specified initial range of this sorted map.
   */
  public SortedMap headMap(Object toKey) {
    return new ImmutableSortedMap(map.headMap(toKey));
  }

  /**
   * Returns a view of the portion of this sorted map whose keys are greater
   * than or equal to <tt>fromKey</tt> .
   *
   * @param fromKey low endpoint (inclusive) of the tailMap.
   * @return a view of the specified final range of this sorted map.
   */
  public SortedMap tailMap(Object fromKey) {
    return new ImmutableSortedMap(map.tailMap(fromKey));
  }

  /**
   * Returns the first (lowest) key currently in this sorted map.
   *
   * @return the first (lowest) key currently in this sorted map.
   * @throws NoSuchElementException if this map is empty.
   */
  public Object firstKey() {
    return map.firstKey();
  }

  /**
   * Returns the last (highest) key currently in this sorted map.
   *
   * @return the last (highest) key currently in this sorted map.
   * @throws NoSuchElementException if this map is empty.
   */
  public Object lastKey() {
    return map.lastKey();
  }

  /**
   * Returns the number of key-value mappings in this map. If the map contains
   * more than <tt>Integer.MAX_VALUE</tt> elements, returns <tt>
   * Integer.MAX_VALUE</tt> .
   *
   * @return the number of key-value mappings in this map.
   */
  public int size() {
    return map.size();
  }

  /**
   * Returns <tt>true</tt> if this map contains a mapping for the specified key.
   *
   * @param key key whose presence in this map is to be tested.
   * @return <tt>true</tt> if this map contains a mapping for the specified
   */
  public boolean containsKey(Object key) {
    return map.containsKey(key);
  }

  /**
   * Returns <tt>true</tt> if this map maps one or more keys to the specified
   * value.
   *
   * @param value value whose presence in this map is to be tested.
   * @return <tt>true</tt> if this map maps one or more keys to the specified
   *      value.
   */
  public boolean containsValue(Object value) {
    return map.containsValue(value);
  }

  // Modification Operations

  /**
   * Associates the specified value with the specified key in this map (optional
   * operation). If the map previously contained a mapping for this key, the old
   * value is replaced by the specified value.
   *
   * @param key key with which the specified value is to be associated.
   * @param value value to be associated with the specified key.
   * @return previous value associated with specified key, or <tt>null</tt> if
   *      there was no mapping for key. A <tt>null</tt> return can also indicate
   *      that the map previously associated <tt>null</tt> with the specified
   *      key, if the implementation supports <tt>null</tt> values.
   * @throws UnsupportedOperationException if the <tt>put</tt> operation is not
   *      supported by this map.
   */
  public Object put(Object key, Object value) {
    throw new UnsupportedOperationException("put not supported by immutablemap");
  }

  /**
   * Removes the mapping for this key from this map if it is present (optional
   * operation). More formally, if this map contains a mapping from key <tt>k
   * </tt> to value <tt>v</tt> such that <code>(key==null ?  k==null : key.equals(k))</code>
   * , that mapping is removed.
   *
   * @param key key whose mapping is to be removed from the map.
   * @return previous value associated with specified key, or <tt>null</tt> if
   *      there was no mapping for key.
   */
  public Object remove(Object key) {
    throw new UnsupportedOperationException("remove not supported by immutablemap");
  }

  /**
   * Copies all of the mappings from the specified map to this map (optional
   * operation).
   *
   * @param t Mappings to be stored in this map.
   */
  public void putAll(Map t) {
    throw new UnsupportedOperationException("putall not supported by immutablemap");
  }

  /**
   * Removes all mappings from this map (optional operation).
   *
   * @throws UnsupportedOperationException clear is not supported by this map.
   */
  public void clear() {
    throw new UnsupportedOperationException("clear not supported by immutablemap");
  }

  /**
   * Returns a set view of the keys contained in this map. The set is backed by
   * the map, so changes to the map are reflected in the set, and vice-versa. If
   * the map is modified while an iteration over the set is in progress, the
   * results of the iteration are undefined. The set supports element removal,
   * which removes the corresponding mapping from the map, via the <tt>
   * Iterator.remove</tt> , <tt>Set.remove</tt> , <tt>removeAll</tt> <tt>
   * retainAll</tt> , and <tt>clear</tt> operations. It does not support the add
   * or <tt>addAll</tt> operations.
   *
   * @return a set view of the keys contained in this map.
   */
  public Set keySet() {
    return map.keySet();
  }

  /**
   * Returns a collection view of the values contained in this map. The
   * collection is backed by the map, so changes to the map are reflected in the
   * collection, and vice-versa. If the map is modified while an iteration over
   * the collection is in progress, the results of the iteration are undefined.
   * The collection supports element removal, which removes the corresponding
   * mapping from the map, via the <tt>Iterator.remove</tt> , <tt>
   * Collection.remove</tt> , <tt>removeAll</tt> , <tt>retainAll</tt> and <tt>
   * clear</tt> operations. It does not support the add or <tt>addAll</tt>
   * operations.
   *
   * @return a collection view of the values contained in this map.
   */
  public Collection values() {
    return map.values();
  }

  /**
   * Returns a set view of the mappings contained in this map. Each element in
   * the returned set is a {@link Map.Entry}. The set is backed by the map, so
   * changes to the map are reflected in the set, and vice-versa. If the map is
   * modified while an iteration over the set is in progress, the results of the
   * iteration are undefined. The set supports element removal, which removes
   * the corresponding mapping from the map, via the <tt>Iterator.remove</tt> ,
   * <tt>Set.remove</tt> , <tt>removeAll</tt> , <tt>retainAll</tt> and <tt>clear
   * </tt> operations. It does not support the <tt>add</tt> or <tt>addAll</tt>
   * operations.
   *
   * @return a set view of the mappings contained in this map.
   */
  public Set entrySet() {
    return map.entrySet();
  }
}