/*
* @(#)TreeMap.java 1.65 04/02/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.util;
/**
* Red-Black tree based implementation of the <tt>SortedMap</tt> interface.
* This class guarantees that the map will be in ascending key order, sorted
* according to the <i>natural order</i> for the key's class (see
* <tt>Comparable</tt>), or by the comparator provided at creation time,
* depending on which constructor is used.<p>
*
* This implementation provides guaranteed log(n) time cost for the
* <tt>containsKey</tt>, <tt>get</tt>, <tt>put</tt> and <tt>remove</tt>
* operations. Algorithms are adaptations of those in Cormen, Leiserson, and
* Rivest's <I>Introduction to Algorithms</I>.<p>
*
* Note that the ordering maintained by a sorted map (whether or not an
* explicit comparator is provided) must be <i>consistent with equals</i> if
* this sorted map is to correctly implement the <tt>Map</tt> interface. (See
* <tt>Comparable</tt> or <tt>Comparator</tt> for a precise definition of
* <i>consistent with equals</i>.) This is so because the <tt>Map</tt>
* interface is defined in terms of the equals operation, but a map performs
* all key comparisons using its <tt>compareTo</tt> (or <tt>compare</tt>)
* method, so two keys that are deemed equal by this method are, from the
* standpoint of the sorted map, equal. The behavior of a sorted map
* <i>is</i> well-defined even if its ordering is inconsistent with equals; it
* just fails to obey the general contract of the <tt>Map</tt> interface.<p>
*
* <b>Note that this implementation is not synchronized.</b> If multiple
* threads access a map concurrently, and at least one of the threads modifies
* the map structurally, it <i>must</i> be synchronized externally. (A
* structural modification is any operation that adds or deletes one or more
* mappings; merely changing the value associated with an existing key is not
* a structural modification.) This is typically accomplished by
* synchronizing on some object that naturally encapsulates the map. If no
* such object exists, the map should be "wrapped" using the
* <tt>Collections.synchronizedMap</tt> method. This is best done at creation
* time, to prevent accidental unsynchronized access to the map:
* <pre>
* Map m = Collections.synchronizedMap(new TreeMap(...));
* </pre><p>
*
* The iterators returned by all of this class's "collection view methods" are
* <i>fail-fast</i>: if the map is structurally modified at any time after the
* iterator is created, in any way except through the iterator's own
* <tt>remove</tt> or <tt>add</tt> methods, the iterator throws a
* <tt>ConcurrentModificationException</tt>. Thus, in the face of concurrent
* modification, the iterator fails quickly and cleanly, rather than risking
* arbitrary, non-deterministic behavior at an undetermined time in the
* future.
*
* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
* as it is, generally speaking, impossible to make any hard guarantees in the
* presence of unsynchronized concurrent modification. Fail-fast iterators
* throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
* Therefore, it would be wrong to write a program that depended on this
* exception for its correctness: <i>the fail-fast behavior of iterators
* should be used only to detect bugs.</i><p>
*
* This class is a member of the
* <a href="{@docRoot}/../guide/collections/index.html">
* Java Collections Framework</a>.
*
* @author Josh Bloch and Doug Lea
* @version 1.65, 02/19/04
* @see Map
* @see HashMap
* @see Hashtable
* @see Comparable
* @see Comparator
* @see Collection
* @see Collections#synchronizedMap(Map)
* @since 1.2
*/
public class TreeMap<K,V>
extends AbstractMap<K,V>
implements SortedMap<K,V>, Cloneable, java.io.Serializable
{
/**
* The Comparator used to maintain order in this TreeMap, or
* null if this TreeMap uses its elements natural ordering.
*
* @serial
*/
private Comparator<? super K> comparator = null;
private transient Entry<K,V> root = null;
/**
* The number of entries in the tree
*/
private transient int size = 0;
/**
* The number of structural modifications to the tree.
*/
private transient int modCount = 0;
private void incrementSize() { modCount++; size++; }
private void decrementSize() { modCount++; size--; }
/**
* Constructs a new, empty map, sorted according to the keys' natural
* order. All keys inserted into the map must implement the
* <tt>Comparable</tt> interface. Furthermore, all such keys must be
* <i>mutually comparable</i>: <tt>k1.compareTo(k2)</tt> must not throw a
* ClassCastException for any elements <tt>k1</tt> and <tt>k2</tt> in the
* map. If the user attempts to put a key into the map that violates this
* constraint (for example, the user attempts to put a string key into a
* map whose keys are integers), the <tt>put(Object key, Object
* value)</tt> call will throw a <tt>ClassCastException</tt>.
*
* @see Comparable
*/
public TreeMap() {
}
/**
* Constructs a new, empty map, sorted according to the given comparator.
* All keys inserted into the map must be <i>mutually comparable</i> by
* the given comparator: <tt>comparator.compare(k1, k2)</tt> must not
* throw a <tt>ClassCastException</tt> for any keys <tt>k1</tt> and
* <tt>k2</tt> in the map. If the user attempts to put a key into the
* map that violates this constraint, the <tt>put(Object key, Object
* value)</tt> call will throw a <tt>ClassCastException</tt>.
*
* @param c the comparator that will be used to sort this map. A
* <tt>null</tt> value indicates that the keys' <i>natural
* ordering</i> should be used.
*/
public TreeMap(Comparator<? super K> c) {
this.comparator = c;
}
/**
* Constructs a new map containing the same mappings as the given map,
* sorted according to the keys' <i>natural order</i>. All keys inserted
* into the new map must implement the <tt>Comparable</tt> interface.
* Furthermore, all such keys must be <i>mutually comparable</i>:
* <tt>k1.compareTo(k2)</tt> must not throw a <tt>ClassCastException</tt>
* for any elements <tt>k1</tt> and <tt>k2</tt> in the map. This method
* runs in n*log(n) time.
*
* @param m the map whose mappings are to be placed in this map.
* @throws ClassCastException the keys in t are not Comparable, or
* are not mutually comparable.
* @throws NullPointerException if the specified map is null.
*/
public TreeMap(Map<? extends K, ? extends V> m) {
putAll(m);
}
/**
* Constructs a new map containing the same mappings as the given
* <tt>SortedMap</tt>, sorted according to the same ordering. This method
* runs in linear time.
*
* @param m the sorted map whose mappings are to be placed in this map,
* and whose comparator is to be used to sort this map.
* @throws NullPointerException if the specified sorted map is null.
*/
public TreeMap(SortedMap<K, ? extends V> m) {
comparator = m.comparator();
try {
buildFromSorted(m.size(), m.entrySet().iterator(), null, null);
} catch (java.io.IOException cannotHappen) {
} catch (ClassNotFoundException cannotHappen) {
}
}
// Query Operations
/**
* Returns the number of key-value mappings in this map.
*
* @return the number of key-value mappings in this map.
*/
public int size() {
return 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 key.
* @throws ClassCastException if the key cannot be compared with the keys
* currently in the map.
* @throws NullPointerException key is <tt>null</tt> and this map uses
* natural ordering, or its comparator does not tolerate
* <tt>null</tt> keys.
*/
public boolean containsKey(Object key) {
return getEntry(key) != null;
}
/**
* Returns <tt>true</tt> if this map maps one or more keys to the
* specified value. More formally, returns <tt>true</tt> if and only if
* this map contains at least one mapping to a value <tt>v</tt> such
* that <tt>(value==null ? v==null : value.equals(v))</tt>. This
* operation will probably require time linear in the Map size for most
* implementations of Map.
*
* @param value value whose presence in this Map is to be tested.
* @return <tt>true</tt> if a mapping to <tt>value</tt> exists;
* <tt>false</tt> otherwise.
* @since 1.2
*/
public boolean containsValue(Object value) {
return (root==null ? false :
(value==null ? valueSearchNull(root)
: valueSearchNonNull(root, value)));
}
private boolean valueSearchNull(Entry n) {
if (n.value == null)
return true;
// Check left and right subtrees for value
return (n.left != null && valueSearchNull(n.left)) ||
(n.right != null && valueSearchNull(n.right));
}
private boolean valueSearchNonNull(Entry n, Object value) {
// Check this node for the value
if (value.equals(n.value))
return true;
// Check left and right subtrees for value
return (n.left != null && valueSearchNonNull(n.left, value)) ||
(n.right != null && valueSearchNonNull(n.right, value));
}
/**
* Returns the value to which this map maps the specified key. Returns
* <tt>null</tt> if the map contains no mapping for this key. A return
* value of <tt>null</tt> does not <i>necessarily</i> indicate that the
* map contains no mapping for the key; it's also possible that the map
* explicitly maps the key to <tt>null</tt>. The <tt>containsKey</tt>
* operation may be used to distinguish these two cases.
*
* @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 the key.
* @throws ClassCastException key cannot be compared with the keys
* currently in the map.
* @throws NullPointerException key is <tt>null</tt> and this map uses
* natural ordering, or its comparator does not tolerate
* <tt>null</tt> keys.
*
* @see #containsKey(Object)
*/
public V get(Object key) {
Entry<K,V> p = getEntry(key);
return (p==null ? null : p.value);
}
/**
* Returns the comparator used to order this map, or <tt>null</tt> if this
* map uses its keys' natural order.
*
* @return the comparator associated with this sorted map, or
* <tt>null</tt> if it uses its keys' natural sort method.
*/
public Comparator<? super K> comparator() {
return comparator;
}
/**
* Returns the first (lowest) key currently in this sorted map.
*
* @return the first (lowest) key currently in this sorted map.
* @throws NoSuchElementException Map is empty.
*/
public K firstKey() {
return key(firstEntry());
}
/**
* Returns the last (highest) key currently in this sorted map.
*
* @return the last (highest) key currently in this sorted map.
* @throws NoSuchElementException Map is empty.
*/
public K lastKey() {
return key(lastEntry());
}
/**
* Copies all of the mappings from the specified map to this map. These
* mappings replace any mappings that this map had for any of the keys
* currently in the specified map.
*
* @param map mappings to be stored in this map.
* @throws ClassCastException class of a key or value in the specified
* map prevents it from being stored in this map.
*
* @throws NullPointerException if the given map is <tt>null</tt> or
* this map does not permit <tt>null</tt> keys and a
* key in the specified map is <tt>null</tt>.
*/
public void putAll(Map<? extends K, ? extends V> map) {
int mapSize = map.size();
if (size==0 && mapSize!=0 && map instanceof SortedMap) {
Comparator c = ((SortedMap)map).comparator();
if (c == comparator || (c != null && c.equals(comparator))) {
++modCount;
try {
buildFromSorted(mapSize, map.entrySet().iterator(),
null, null);
} catch (java.io.IOException cannotHappen) {
} catch (ClassNotFoundException cannotHappen) {
}
return;
}
}
super.putAll(map);
}
/**
* Returns this map's entry for the given key, or <tt>null</tt> if the map
* does not contain an entry for the key.
*
* @return this map's entry for the given key, or <tt>null</tt> if the map
* does not contain an entry for the key.
* @throws ClassCastException if the key cannot be compared with the keys
* currently in the map.
* @throws NullPointerException key is <tt>null</tt> and this map uses
* natural order, or its comparator does not tolerate *
* <tt>null</tt> keys.
*/
private Entry<K,V> getEntry(Object key) {
Entry<K,V> p = root;
K k = (K) key;
while (p != null) {
int cmp = compare(k, p.key);
if (cmp == 0)
return p;
else if (cmp < 0)
p = p.left;
else
p = p.right;
}
return null;
}
/**
* Gets the entry corresponding to the specified key; if no such entry
* exists, returns the entry for the least key greater than the specified
* key; if no such entry exists (i.e., the greatest key in the Tree is less
* than the specified key), returns <tt>null</tt>.
*/
private Entry<K,V> getCeilEntry(K key) {
Entry<K,V> p = root;
if (p==null)
return null;
while (true) {
int cmp = compare(key, p.key);
if (cmp == 0) {
return p;
} else if (cmp < 0) {
if (p.left != null)
p = p.left;
else
return p;
} else {
if (p.right != null) {
p = p.right;
} else {
Entry<K,V> parent = p.parent;
Entry<K,V> ch = p;
while (parent != null && ch == parent.right) {
ch = parent;
parent = parent.parent;
}
return parent;
}
}
}
}
/**
* Returns the entry for the greatest key less than the specified key; if
* no such entry exists (i.e., the least key in the Tree is greater than
* the specified key), returns <tt>null</tt>.
*/
private Entry<K,V> getPrecedingEntry(K key) {
Entry<K,V> p = root;
if (p==null)
return null;
while (true) {
int cmp = compare(key, p.key);
if (cmp > 0) {
if (p.right != null)
p = p.right;
else
return p;
} else {
if (p.left != null) {
p = p.left;
} else {
Entry<K,V> parent = p.parent;
Entry<K,V> ch = p;
while (parent != null && ch == parent.left) {
ch = parent;
parent = parent.parent;
}
return parent;
}
}
}
}
/**
* Returns the key corresponding to the specified Entry. Throw
* NoSuchElementException if the Entry is <tt>null</tt>.
*/
private static <K> K key(Entry<K,?> e) {
if (e==null)
throw new NoSuchElementException();
return e.key;
}
/**
* Associates the specified value with the specified key in this map.
* If the map previously contained a mapping for this key, the old
* value is replaced.
*
* @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.
* @throws ClassCastException key cannot be compared with the keys
* currently in the map.
* @throws NullPointerException key is <tt>null</tt> and this map uses
* natural order, or its comparator does not tolerate
* <tt>null</tt> keys.
*/
public V put(K key, V value) {
Entry<K,V> t = root;
if (t == null) {
incrementSize();
root = new Entry<K,V>(key, value, null);
return null;
}
while (true) {
int cmp = compare(key, t.key);
if (cmp == 0) {
return t.setValue(value);
} else if (cmp < 0) {
if (t.left != null) {
t = t.left;
} else {
incrementSize();
t.left = new Entry<K,V>(key, value, t);
fixAfterInsertion(t.left);
return null;
}
} else { // cmp > 0
if (t.right != null) {
t = t.right;
} else {
incrementSize();
t.right = new Entry<K,V>(key, value, t);
fixAfterInsertion(t.right);
return null;
}
}
}
}
/**
* Removes the mapping for this key from this TreeMap if present.
*
* @param key key for which mapping should be removed
* @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.
*
* @throws ClassCastException key cannot be compared with the keys
* currently in the map.
* @throws NullPointerException key is <tt>null</tt> and this map uses
* natural order, or its comparator does not tolerate
* <tt>null</tt> keys.
*/
public V remove(Object key) {
Entry<K,V> p = getEntry(key);
if (p == null)
return null;
V oldValue = p.value;
deleteEntry(p);
return oldValue;
}
/**
* Removes all mappings from this TreeMap.
*/
public void clear() {
modCount++;
size = 0;
root = null;
}
/**
* Returns a shallow copy of this <tt>TreeMap</tt> instance. (The keys and
* values themselves are not cloned.)
*
* @return a shallow copy of this Map.
*/
public Object clone() {
TreeMap<K,V> clone = null;
try {
clone = (TreeMap<K,V>) super.clone();
} catch (CloneNotSupportedException e) {
throw new InternalError();
}
// Put clone into "virgin" state (except for comparator)
clone.root = null;
clone.size = 0;
clone.modCount = 0;
clone.entrySet = null;
// Initialize clone with our mappings
try {
clone.buildFromSorted(size, entrySet().iterator(), null, null);
} catch (java.io.IOException cannotHappen) {
} catch (ClassNotFoundException cannotHappen) {
}
return clone;
}
// Views
/**
* This field is initialized to contain an instance of the entry set
* view the first time this view is requested. The view is stateless,
* so there's no reason to create more than one.
*/
private transient volatile Set<Map.Entry<K,V>> entrySet = null;
/**
* Returns a Set view of the keys contained in this map. The set's
* iterator will return the keys in ascending order. The map is backed by
* this <tt>TreeMap</tt> instance, so changes to this map are reflected in
* the Set, and vice-versa. 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 keys contained in this TreeMap.
*/
public Set<K> keySet() {
if (keySet == null) {
keySet = new AbstractSet<K>() {
public Iterator<K> iterator() {
return new KeyIterator();
}
public int size() {
return TreeMap.this.size();
}
public boolean contains(Object o) {
return containsKey(o);
}
public boolean remove(Object o) {
int oldSize = size;
TreeMap.this.remove(o);
return size != oldSize;
}
public void clear() {
TreeMap.this.clear();
}
};
}
return keySet;
}
/**
* Returns a collection view of the values contained in this map. The
* collection's iterator will return the values in the order that their
* corresponding keys appear in the tree. The collection is backed by
* this <tt>TreeMap</tt> instance, so changes to this map are reflected in
* the collection, and vice-versa. The collection supports element
* removal, which removes the corresponding mapping from the map through
* 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 <tt>add</tt> or <tt>addAll</tt> operations.
*
* @return a collection view of the values contained in this map.
*/
public Collection<V> values() {
if (values == null) {
values = new AbstractCollection<V>() {
public Iterator<V> iterator() {
return new ValueIterator();
}
public int size() {
return TreeMap.this.size();
}
public boolean contains(Object o) {
for (Entry<K,V> e = firstEntry(); e != null; e = successor(e))
if (valEquals(e.getValue(), o))
return true;
return false;
}
public boolean remove(Object o) {
for (Entry<K,V> e = firstEntry(); e != null; e = successor(e)) {
if (valEquals(e.getValue(), o)) {
deleteEntry(e);
return true;
}
}
return false;
}
public void clear() {
TreeMap.this.clear();
}
};
}
return values;
}
/**
* Returns a set view of the mappings contained in this map. The set's
* iterator returns the mappings in ascending key order. Each element in
* the returned set is a <tt>Map.Entry</tt>. The set is backed by this
* map, so changes to this map are reflected in the set, and vice-versa.
* The set supports element removal, which removes the corresponding
* mapping from the TreeMap, through 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.
* @see Map.Entry
*/
public Set<Map.Entry<K,V>> entrySet() {
if (entrySet == null) {
entrySet = new AbstractSet<Map.Entry<K,V>>() {
public Iterator<Map.Entry<K,V>> iterator() {
return new EntryIterator();
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<K,V> entry = (Map.Entry<K,V>) o;
V value = entry.getValue();
Entry<K,V> p = getEntry(entry.getKey());
return p != null && valEquals(p.getValue(), value);
}
public boolean remove(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<K,V> entry = (Map.Entry<K,V>) o;
V value = entry.getValue();
Entry<K,V> p = getEntry(entry.getKey());
if (p != null && valEquals(p.getValue(), value)) {
deleteEntry(p);
return true;
}
return false;
}
public int size() {
return TreeMap.this.size();
}
public void clear() {
TreeMap.this.clear();
}
};
}
return entrySet;
}
/**
* 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.
* The returned sorted map supports all optional map operations.<p>
*
* The sorted map returned by this method will throw an
* <tt>IllegalArgumentException</tt> if the user attempts to insert a key
* less than <tt>fromKey</tt> or greater than or equal to
* <tt>toKey</tt>.<p>
*
* Note: this method always returns a <i>half-open range</i> (which
* includes its low endpoint but not its high endpoint). If you need a
* <i>closed range</i> (which includes both endpoints), and the key type
* allows for calculation of the successor a given key, merely request the
* subrange from <tt>lowEndpoint</tt> to <tt>successor(highEndpoint)</tt>.
* For example, suppose that <tt>m</tt> is a sorted map whose keys are
* strings. The following idiom obtains a view containing all of the
* key-value mappings in <tt>m</tt> whose keys are between <tt>low</tt>
* and <tt>high</tt>, inclusive:
* <pre> SortedMap sub = m.submap(low, high+"\0");</pre>
* A similar technique can be used to generate an <i>open range</i> (which
* contains neither endpoint). The following idiom obtains a view
* containing all of the key-value mappings in <tt>m</tt> whose keys are
* between <tt>low</tt> and <tt>high</tt>, exclusive:
* <pre> SortedMap sub = m.subMap(low+"\0", high);</pre>
*
* @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 uses natural order, or its
* comparator does not tolerate <tt>null</tt> keys.
*/
public SortedMap<K,V> subMap(K fromKey, K toKey) {
return new SubMap(fromKey, 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. The returned sorted map supports all optional map
* operations.<p>
*
* The sorted map returned by this method will throw an
* <tt>IllegalArgumentException</tt> if the user attempts to insert a key
* greater than or equal to <tt>toKey</tt>.<p>
*
* Note: this method always returns a view that does not contain its
* (high) endpoint. If you need a view that does contain this endpoint,
* and the key type allows for calculation of the successor a given key,
* merely request a headMap bounded by <tt>successor(highEndpoint)</tt>.
* For example, suppose that suppose that <tt>m</tt> is a sorted map whose
* keys are strings. The following idiom obtains a view containing all of
* the key-value mappings in <tt>m</tt> whose keys are less than or equal
* to <tt>high</tt>:
* <pre>
* SortedMap head = m.headMap(high+"\0");
* </pre>
*
* @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 IllegalArgumentException if this map is itself a subMap,
* headMap, or tailMap, and <tt>toKey</tt> is not within the
* specified range of the subMap, headMap, or tailMap.
* @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt> and
* this map uses natural order, or its comparator does not
* tolerate <tt>null</tt> keys.
*/
public SortedMap<K,V> headMap(K toKey) {
return new SubMap(toKey, true);
}
/**
* 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. The returned sorted map supports all optional map
* operations.<p>
*
* The sorted map returned by this method will throw an
* <tt>IllegalArgumentException</tt> if the user attempts to insert a key
* less than <tt>fromKey</tt>.<p>
*
* Note: this method always returns a view that contains its (low)
* endpoint. If you need a view that does not contain this endpoint, and
* the element type allows for calculation of the successor a given value,
* merely request a tailMap bounded by <tt>successor(lowEndpoint)</tt>.
* For example, suppose that <tt>m</tt> is a sorted map whose keys
* are strings. The following idiom obtains a view containing
* all of the key-value mappings in <tt>m</tt> whose keys are strictly
* greater than <tt>low</tt>: <pre>
* SortedMap tail = m.tailMap(low+"\0");
* </pre>
*
* @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 IllegalArgumentException if this map is itself a subMap,
* headMap, or tailMap, and <tt>fromKey</tt> is not within the
* specified range of the subMap, headMap, or tailMap.
* @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt> and
* this map uses natural order, or its comparator does not
* tolerate <tt>null</tt> keys.
*/
public SortedMap<K,V> tailMap(K fromKey) {
return new SubMap(fromKey, false);
}
private class SubMap
extends AbstractMap<K,V>
implements SortedMap<K,V>, java.io.Serializable {
private static final long serialVersionUID = -6520786458950516097L;
/**
* fromKey is significant only if fromStart is false. Similarly,
* toKey is significant only if toStart is false.
*/
private boolean fromStart = false, toEnd = false;
private K fromKey, toKey;
SubMap(K fromKey, K toKey) {
if (compare(fromKey, toKey) > 0)
throw new IllegalArgumentException("fromKey > toKey");
this.fromKey = fromKey;
this.toKey = toKey;
}
SubMap(K key, boolean headMap) {
compare(key, key); // Type-check key
if (headMap) {
fromStart = true;
toKey = key;
} else {
toEnd = true;
fromKey = key;
}
}
SubMap(boolean fromStart, K fromKey, boolean toEnd, K toKey) {
this.fromStart = fromStart;
this.fromKey= fromKey;
this.toEnd = toEnd;
this.toKey = toKey;
}
public boolean isEmpty() {
return entrySet.isEmpty();
}
public boolean containsKey(Object key) {
return inRange((K) key) && TreeMap.this.containsKey(key);
}
public V get(Object key) {
if (!inRange((K) key))
return null;
return TreeMap.this.get(key);
}
public V put(K key, V value) {
if (!inRange(key))
throw new IllegalArgumentException("key out of range");
return TreeMap.this.put(key, value);
}
public Comparator<? super K> comparator() {
return comparator;
}
public K firstKey() {
TreeMap.Entry<K,V> e = fromStart ? firstEntry() : getCeilEntry(fromKey);
K first = key(e);
if (!toEnd && compare(first, toKey) >= 0)
throw(new NoSuchElementException());
return first;
}
public K lastKey() {
TreeMap.Entry<K,V> e = toEnd ? lastEntry() : getPrecedingEntry(toKey);
K last = key(e);
if (!fromStart && compare(last, fromKey) < 0)
throw(new NoSuchElementException());
return last;
}
private transient Set<Map.Entry<K,V>> entrySet = new EntrySetView();
public Set<Map.Entry<K,V>> entrySet() {
return entrySet;
}
private class EntrySetView extends AbstractSet<Map.Entry<K,V>> {
private transient int size = -1, sizeModCount;
public int size() {
if (size == -1 || sizeModCount != TreeMap.this.modCount) {
size = 0; sizeModCount = TreeMap.this.modCount;
Iterator i = iterator();
while (i.hasNext()) {
size++;
i.next();
}
}
return size;
}
public boolean isEmpty() {
return !iterator().hasNext();
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<K,V> entry = (Map.Entry<K,V>) o;
K key = entry.getKey();
if (!inRange(key))
return false;
TreeMap.Entry node = getEntry(key);
return node != null &&
valEquals(node.getValue(), entry.getValue());
}
public boolean remove(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<K,V> entry = (Map.Entry<K,V>) o;
K key = entry.getKey();
if (!inRange(key))
return false;
TreeMap.Entry<K,V> node = getEntry(key);
if (node!=null && valEquals(node.getValue(),entry.getValue())){
deleteEntry(node);
return true;
}
return false;
}
public Iterator<Map.Entry<K,V>> iterator() {
return new SubMapEntryIterator(
(fromStart ? firstEntry() : getCeilEntry(fromKey)),
(toEnd ? null : getCeilEntry(toKey)));
}
}
public SortedMap<K,V> subMap(K fromKey, K toKey) {
if (!inRange2(fromKey))
throw new IllegalArgumentException("fromKey out of range");
if (!inRange2(toKey))
throw new IllegalArgumentException("toKey out of range");
return new SubMap(fromKey, toKey);
}
public SortedMap<K,V> headMap(K toKey) {
if (!inRange2(toKey))
throw new IllegalArgumentException("toKey out of range");
return new SubMap(fromStart, fromKey, false, toKey);
}
public SortedMap<K,V> tailMap(K fromKey) {
if (!inRange2(fromKey))
throw new IllegalArgumentException("fromKey out of range");
return new SubMap(false, fromKey, toEnd, toKey);
}
private boolean inRange(K key) {
return (fromStart || compare(key, fromKey) >= 0) &&
(toEnd || compare(key, toKey) < 0);
}
// This form allows the high endpoint (as well as all legit keys)
private boolean inRange2(K key) {
return (fromStart || compare(key, fromKey) >= 0) &&
(toEnd || compare(key, toKey) <= 0);
}
}
/**
* TreeMap Iterator.
*/
private abstract class PrivateEntryIterator<T> implements Iterator<T> {
private int expectedModCount = TreeMap.this.modCount;
private Entry<K,V> lastReturned = null;
Entry<K,V> next;
PrivateEntryIterator() {
next = firstEntry();
}
// Used by SubMapEntryIterator
PrivateEntryIterator(Entry<K,V> first) {
next = first;
}
public boolean hasNext() {
return next != null;
}
final Entry<K,V> nextEntry() {
if (next == null)
throw new NoSuchElementException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
lastReturned = next;
next = successor(next);
return lastReturned;
}
public void remove() {
if (lastReturned == null)
throw new IllegalStateException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
if (lastReturned.left != null && lastReturned.right != null)
next = lastReturned;
deleteEntry(lastReturned);
expectedModCount++;
lastReturned = null;
}
}
private class EntryIterator extends PrivateEntryIterator<Map.Entry<K,V>> {
public Map.Entry<K,V> next() {
return nextEntry();
}
}
private class KeyIterator extends PrivateEntryIterator<K> {
public K next() {
return nextEntry().key;
}
}
private class ValueIterator extends PrivateEntryIterator<V> {
public V next() {
return nextEntry().value;
}
}
private class SubMapEntryIterator extends PrivateEntryIterator<Map.Entry<K,V>> {
private final K firstExcludedKey;
SubMapEntryIterator(Entry<K,V> first, Entry<K,V> firstExcluded) {
super(first);
firstExcludedKey = (firstExcluded == null
? null
: firstExcluded.key);
}
public boolean hasNext() {
return next != null && next.key != firstExcludedKey;
}
public Map.Entry<K,V> next() {
if (next == null || next.key == firstExcludedKey)
throw new NoSuchElementException();
return nextEntry();
}
}
/**
* Compares two keys using the correct comparison method for this TreeMap.
*/
private int compare(K k1, K k2) {
return (comparator==null ? ((Comparable</*-*/K>)k1).compareTo(k2)
: comparator.compare((K)k1, (K)k2));
}
/**
* Test two values for equality. Differs from o1.equals(o2) only in
* that it copes with <tt>null</tt> o1 properly.
*/
private static boolean valEquals(Object o1, Object o2) {
return (o1==null ? o2==null : o1.equals(o2));
}
private static final boolean RED = false;
private static final boolean BLACK = true;
/**
* Node in the Tree. Doubles as a means to pass key-value pairs back to
* user (see Map.Entry).
*/
static class Entry<K,V> implements Map.Entry<K,V> {
K key;
V value;
Entry<K,V> left = null;
Entry<K,V> right = null;
Entry<K,V> parent;
boolean color = BLACK;
/**
* Make a new cell with given key, value, and parent, and with
* <tt>null</tt> child links, and BLACK color.
*/
Entry(K key, V value, Entry<K,V> parent) {
this.key = key;
this.value = value;
this.parent = parent;
}
/**
* Returns the key.
*
* @return the key.
*/
public K getKey() {
return key;
}
/**
* Returns the value associated with the key.
*
* @return the value associated with the key.
*/
public V getValue() {
return value;
}
/**
* Replaces the value currently associated with the key with the given
* value.
*
* @return the value associated with the key before this method was
* called.
*/
public V setValue(V value) {
V oldValue = this.value;
this.value = value;
return oldValue;
}
public boolean equals(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry e = (Map.Entry)o;
return valEquals(key,e.getKey()) && valEquals(value,e.getValue());
}
public int hashCode() {
int keyHash = (key==null ? 0 : key.hashCode());
int valueHash = (value==null ? 0 : value.hashCode());
return keyHash ^ valueHash;
}
public String toString() {
return key + "=" + value;
}
}
/**
* Returns the first Entry in the TreeMap (according to the TreeMap's
* key-sort function). Returns null if the TreeMap is empty.
*/
private Entry<K,V> firstEntry() {
Entry<K,V> p = root;
if (p != null)
while (p.left != null)
p = p.left;
return p;
}
/**
* Returns the last Entry in the TreeMap (according to the TreeMap's
* key-sort function). Returns null if the TreeMap is empty.
*/
private Entry<K,V> lastEntry() {
Entry<K,V> p = root;
if (p != null)
while (p.right != null)
p = p.right;
return p;
}
/**
* Returns the successor of the specified Entry, or null if no such.
*/
private Entry<K,V> successor(Entry<K,V> t) {
if (t == null)
return null;
else if (t.right != null) {
Entry<K,V> p = t.right;
while (p.left != null)
p = p.left;
return p;
} else {
Entry<K,V> p = t.parent;
Entry<K,V> ch = t;
while (p != null && ch == p.right) {
ch = p;
p = p.parent;
}
return p;
}
}
/**
* Balancing operations.
*
* Implementations of rebalancings during insertion and deletion are
* slightly different than the CLR version. Rather than using dummy
* nilnodes, we use a set of accessors that deal properly with null. They
* are used to avoid messiness surrounding nullness checks in the main
* algorithms.
*/
private static <K,V> boolean colorOf(Entry<K,V> p) {
return (p == null ? BLACK : p.color);
}
private static <K,V> Entry<K,V> parentOf(Entry<K,V> p) {
return (p == null ? null: p.parent);
}
private static <K,V> void setColor(Entry<K,V> p, boolean c) {
if (p != null)
p.color = c;
}
private static <K,V> Entry<K,V> leftOf(Entry<K,V> p) {
return (p == null) ? null: p.left;
}
private static <K,V> Entry<K,V> rightOf(Entry<K,V> p) {
return (p == null) ? null: p.right;
}
/** From CLR **/
private void rotateLeft(Entry<K,V> p) {
Entry<K,V> r = p.right;
p.right = r.left;
if (r.left != null)
r.left.parent = p;
r.parent = p.parent;
if (p.parent == null)
root = r;
else if (p.parent.left == p)
p.parent.left = r;
else
p.parent.right = r;
r.left = p;
p.parent = r;
}
/** From CLR **/
private void rotateRight(Entry<K,V> p) {
Entry<K,V> l = p.left;
p.left = l.right;
if (l.right != null) l.right.parent = p;
l.parent = p.parent;
if (p.parent == null)
root = l;
else if (p.parent.right == p)
p.parent.right = l;
else p.parent.left = l;
l.right = p;
p.parent = l;
}
/** From CLR **/
private void fixAfterInsertion(Entry<K,V> x) {
x.color = RED;
while (x != null && x != root && x.parent.color == RED) {
if (parentOf(x) == leftOf(parentOf(parentOf(x)))) {
Entry<K,V> y = rightOf(parentOf(parentOf(x)));
if (colorOf(y) == RED) {
setColor(parentOf(x), BLACK);
setColor(y, BLACK);
setColor(parentOf(parentOf(x)), RED);
x = parentOf(parentOf(x));
} else {
if (x == rightOf(parentOf(x))) {
x = parentOf(x);
rotateLeft(x);
}
setColor(parentOf(x), BLACK);
setColor(parentOf(parentOf(x)), RED);
if (parentOf(parentOf(x)) != null)
rotateRight(parentOf(parentOf(x)));
}
} else {
Entry<K,V> y = leftOf(parentOf(parentOf(x)));
if (colorOf(y) == RED) {
setColor(parentOf(x), BLACK);
setColor(y, BLACK);
setColor(parentOf(parentOf(x)), RED);
x = parentOf(parentOf(x));
} else {
if (x == leftOf(parentOf(x))) {
x = parentOf(x);
rotateRight(x);
}
setColor(parentOf(x), BLACK);
setColor(parentOf(parentOf(x)), RED);
if (parentOf(parentOf(x)) != null)
rotateLeft(parentOf(parentOf(x)));
}
}
}
root.color = BLACK;
}
/**
* Delete node p, and then rebalance the tree.
*/
private void deleteEntry(Entry<K,V> p) {
decrementSize();
// If strictly internal, copy successor's element to p and then make p
// point to successor.
if (p.left != null && p.right != null) {
Entry<K,V> s = successor (p);
p.key = s.key;
p.value = s.value;
p = s;
} // p has 2 children
// Start fixup at replacement node, if it exists.
Entry<K,V> replacement = (p.left != null ? p.left : p.right);
if (replacement != null) {
// Link replacement to parent
replacement.parent = p.parent;
if (p.parent == null)
root = replacement;
else if (p == p.parent.left)
p.parent.left = replacement;
else
p.parent.right = replacement;
// Null out links so they are OK to use by fixAfterDeletion.
p.left = p.right = p.parent = null;
// Fix replacement
if (p.color == BLACK)
fixAfterDeletion(replacement);
} else if (p.parent == null) { // return if we are the only node.
root = null;
} else { // No children. Use self as phantom replacement and unlink.
if (p.color == BLACK)
fixAfterDeletion(p);
if (p.parent != null) {
if (p == p.parent.left)
p.parent.left = null;
else if (p == p.parent.right)
p.parent.right = null;
p.parent = null;
}
}
}
/** From CLR **/
private void fixAfterDeletion(Entry<K,V> x) {
while (x != root && colorOf(x) == BLACK) {
if (x == leftOf(parentOf(x))) {
Entry<K,V> sib = rightOf(parentOf(x));
if (colorOf(sib) == RED) {
setColor(sib, BLACK);
setColor(parentOf(x), RED);
rotateLeft(parentOf(x));
sib = rightOf(parentOf(x));
}
if (colorOf(leftOf(sib)) == BLACK &&
colorOf(rightOf(sib)) == BLACK) {
setColor(sib, RED);
x = parentOf(x);
} else {
if (colorOf(rightOf(sib)) == BLACK) {
setColor(leftOf(sib), BLACK);
setColor(sib, RED);
rotateRight(sib);
sib = rightOf(parentOf(x));
}
setColor(sib, colorOf(parentOf(x)));
setColor(parentOf(x), BLACK);
setColor(rightOf(sib), BLACK);
rotateLeft(parentOf(x));
x = root;
}
} else { // symmetric
Entry<K,V> sib = leftOf(parentOf(x));
if (colorOf(sib) == RED) {
setColor(sib, BLACK);
setColor(parentOf(x), RED);
rotateRight(parentOf(x));
sib = leftOf(parentOf(x));
}
if (colorOf(rightOf(sib)) == BLACK &&
colorOf(leftOf(sib)) == BLACK) {
setColor(sib, RED);
x = parentOf(x);
} else {
if (colorOf(leftOf(sib)) == BLACK) {
setColor(rightOf(sib), BLACK);
setColor(sib, RED);
rotateLeft(sib);
sib = leftOf(parentOf(x));
}
setColor(sib, colorOf(parentOf(x)));
setColor(parentOf(x), BLACK);
setColor(leftOf(sib), BLACK);
rotateRight(parentOf(x));
x = root;
}
}
}
setColor(x, BLACK);
}
private static final long serialVersionUID = 919286545866124006L;
/**
* Save the state of the <tt>TreeMap</tt> instance to a stream (i.e.,
* serialize it).
*
* @serialData The <i>size</i> of the TreeMap (the number of key-value
* mappings) is emitted (int), followed by the key (Object)
* and value (Object) for each key-value mapping represented
* by the TreeMap. The key-value mappings are emitted in
* key-order (as determined by the TreeMap's Comparator,
* or by the keys' natural ordering if the TreeMap has no
* Comparator).
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException {
// Write out the Comparator and any hidden stuff
s.defaultWriteObject();
// Write out size (number of Mappings)
s.writeInt(size);
// Write out keys and values (alternating)
for (Iterator<Map.Entry<K,V>> i = entrySet().iterator(); i.hasNext(); ) {
Map.Entry<K,V> e = i.next();
s.writeObject(e.getKey());
s.writeObject(e.getValue());
}
}
/**
* Reconstitute the <tt>TreeMap</tt> instance from a stream (i.e.,
* deserialize it).
*/
private void readObject(final java.io.ObjectInputStream s)
throws java.io.IOException, ClassNotFoundException {
// Read in the Comparator and any hidden stuff
s.defaultReadObject();
// Read in size
int size = s.readInt();
buildFromSorted(size, null, s, null);
}
/** Intended to be called only from TreeSet.readObject **/
void readTreeSet(int size, java.io.ObjectInputStream s, V defaultVal)
throws java.io.IOException, ClassNotFoundException {
buildFromSorted(size, null, s, defaultVal);
}
/** Intended to be called only from TreeSet.addAll **/
void addAllForTreeSet(SortedSet<Map.Entry<K,V>> set, V defaultVal) {
try {
buildFromSorted(set.size(), set.iterator(), null, defaultVal);
} catch (java.io.IOException cannotHappen) {
} catch (ClassNotFoundException cannotHappen) {
}
}
/**
* Linear time tree building algorithm from sorted data. Can accept keys
* and/or values from iterator or stream. This leads to too many
* parameters, but seems better than alternatives. The four formats
* that this method accepts are:
*
* 1) An iterator of Map.Entries. (it != null, defaultVal == null).
* 2) An iterator of keys. (it != null, defaultVal != null).
* 3) A stream of alternating serialized keys and values.
* (it == null, defaultVal == null).
* 4) A stream of serialized keys. (it == null, defaultVal != null).
*
* It is assumed that the comparator of the TreeMap is already set prior
* to calling this method.
*
* @param size the number of keys (or key-value pairs) to be read from
* the iterator or stream.
* @param it If non-null, new entries are created from entries
* or keys read from this iterator.
* @param str If non-null, new entries are created from keys and
* possibly values read from this stream in serialized form.
* Exactly one of it and str should be non-null.
* @param defaultVal if non-null, this default value is used for
* each value in the map. If null, each value is read from
* iterator or stream, as described above.
* @throws IOException propagated from stream reads. This cannot
* occur if str is null.
* @throws ClassNotFoundException propagated from readObject.
* This cannot occur if str is null.
*/
private
void buildFromSorted(int size, Iterator it,
java.io.ObjectInputStream str,
V defaultVal)
throws java.io.IOException, ClassNotFoundException {
this.size = size;
root =
buildFromSorted(0, 0, size-1, computeRedLevel(size),
it, str, defaultVal);
}
/**
* Recursive "helper method" that does the real work of the
* of the previous method. Identically named parameters have
* identical definitions. Additional parameters are documented below.
* It is assumed that the comparator and size fields of the TreeMap are
* already set prior to calling this method. (It ignores both fields.)
*
* @param level the current level of tree. Initial call should be 0.
* @param lo the first element index of this subtree. Initial should be 0.
* @param hi the last element index of this subtree. Initial should be
* size-1.
* @param redLevel the level at which nodes should be red.
* Must be equal to computeRedLevel for tree of this size.
*/
private final Entry<K,V> buildFromSorted(int level, int lo, int hi,
int redLevel,
Iterator it,
java.io.ObjectInputStream str,
V defaultVal)
throws java.io.IOException, ClassNotFoundException {
/*
* Strategy: The root is the middlemost element. To get to it, we
* have to first recursively construct the entire left subtree,
* so as to grab all of its elements. We can then proceed with right
* subtree.
*
* The lo and hi arguments are the minimum and maximum
* indices to pull out of the iterator or stream for current subtree.
* They are not actually indexed, we just proceed sequentially,
* ensuring that items are extracted in corresponding order.
*/
if (hi < lo) return null;
int mid = (lo + hi) / 2;
Entry<K,V> left = null;
if (lo < mid)
left = buildFromSorted(level+1, lo, mid - 1, redLevel,
it, str, defaultVal);
// extract key and/or value from iterator or stream
K key;
V value;
if (it != null) {
if (defaultVal==null) {
Map.Entry<K,V> entry = (Map.Entry<K,V>)it.next();
key = entry.getKey();
value = entry.getValue();
} else {
key = (K)it.next();
value = defaultVal;
}
} else { // use stream
key = (K) str.readObject();
value = (defaultVal != null ? defaultVal : (V) str.readObject());
}
Entry<K,V> middle = new Entry<K,V>(key, value, null);
// color nodes in non-full bottommost level red
if (level == redLevel)
middle.color = RED;
if (left != null) {
middle.left = left;
left.parent = middle;
}
if (mid < hi) {
Entry<K,V> right = buildFromSorted(level+1, mid+1, hi, redLevel,
it, str, defaultVal);
middle.right = right;
right.parent = middle;
}
return middle;
}
/**
* Find the level down to which to assign all nodes BLACK. This is the
* last `full' level of the complete binary tree produced by
* buildTree. The remaining nodes are colored RED. (This makes a `nice'
* set of color assignments wrt future insertions.) This level number is
* computed by finding the number of splits needed to reach the zeroeth
* node. (The answer is ~lg(N), but in any case must be computed by same
* quick O(lg(N)) loop.)
*/
private static int computeRedLevel(int sz) {
int level = 0;
for (int m = sz - 1; m >= 0; m = m / 2 - 1)
level++;
return level;
}
}
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