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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
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tree976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/util/TreeSet.java
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+/* TreeSet.java -- a class providing a TreeMap-backed SortedSet
+ Copyright (C) 1999, 2000, 2001, 2004, 2005 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING. If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library. Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module. An independent module is a module which is not derived from
+or based on this library. If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so. If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package java.util;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+
+/**
+ * This class provides a TreeMap-backed implementation of the SortedSet
+ * interface. The elements will be sorted according to their <i>natural
+ * order</i>, or according to the provided <code>Comparator</code>.<p>
+ *
+ * Most operations are O(log n), but there is so much overhead that this
+ * makes small sets expensive. Note that the ordering must be <i>consistent
+ * with equals</i> to correctly implement the Set interface. If this
+ * condition is violated, the set is still well-behaved, but you may have
+ * suprising results when comparing it to other sets.<p>
+ *
+ * This implementation is not synchronized. If you need to share this between
+ * multiple threads, do something like:<br>
+ * <code>SortedSet s
+ * = Collections.synchronizedSortedSet(new TreeSet(...));</code><p>
+ *
+ * The iterators are <i>fail-fast</i>, meaning that any structural
+ * modification, except for <code>remove()</code> called on the iterator
+ * itself, cause the iterator to throw a
+ * <code>ConcurrentModificationException</code> rather than exhibit
+ * non-deterministic behavior.
+ *
+ * @author Jon Zeppieri
+ * @author Bryce McKinlay
+ * @author Eric Blake (ebb9@email.byu.edu)
+ * @author Tom Tromey (tromey@redhat.com)
+ * @author Andrew John Hughes (gnu_andrew@member.fsf.org)
+ * @see Collection
+ * @see Set
+ * @see HashSet
+ * @see LinkedHashSet
+ * @see Comparable
+ * @see Comparator
+ * @see Collections#synchronizedSortedSet(SortedSet)
+ * @see TreeMap
+ * @since 1.2
+ * @status updated to 1.6
+ */
+public class TreeSet<T> extends AbstractSet<T>
+ implements NavigableSet<T>, Cloneable, Serializable
+{
+ /**
+ * Compatible with JDK 1.2.
+ */
+ private static final long serialVersionUID = -2479143000061671589L;
+
+ /**
+ * The NavigableMap which backs this Set.
+ */
+ // Not final because of readObject. This will always be one of TreeMap or
+ // TreeMap.SubMap, which both extend AbstractMap.
+ private transient NavigableMap<T, String> map;
+
+ /**
+ * Construct a new TreeSet whose backing TreeMap using the "natural"
+ * ordering of keys. Elements that are not mutually comparable will cause
+ * ClassCastExceptions down the road.
+ *
+ * @see Comparable
+ */
+ public TreeSet()
+ {
+ map = new TreeMap<T, String>();
+ }
+
+ /**
+ * Construct a new TreeSet whose backing TreeMap uses the supplied
+ * Comparator. Elements that are not mutually comparable will cause
+ * ClassCastExceptions down the road.
+ *
+ * @param comparator the Comparator this Set will use
+ */
+ public TreeSet(Comparator<? super T> comparator)
+ {
+ map = new TreeMap<T, String>(comparator);
+ }
+
+ /**
+ * Construct a new TreeSet whose backing TreeMap uses the "natural"
+ * orering of the keys and which contains all of the elements in the
+ * supplied Collection. This runs in n*log(n) time.
+ *
+ * @param collection the new Set will be initialized with all
+ * of the elements in this Collection
+ * @throws ClassCastException if the elements of the collection are not
+ * comparable
+ * @throws NullPointerException if the collection is null
+ * @see Comparable
+ */
+ public TreeSet(Collection<? extends T> collection)
+ {
+ map = new TreeMap<T, String>();
+ addAll(collection);
+ }
+
+ /**
+ * Construct a new TreeSet, using the same key ordering as the supplied
+ * SortedSet and containing all of the elements in the supplied SortedSet.
+ * This constructor runs in linear time.
+ *
+ * @param sortedSet the new TreeSet will use this SortedSet's comparator
+ * and will initialize itself with all its elements
+ * @throws NullPointerException if sortedSet is null
+ */
+ public TreeSet(SortedSet<T> sortedSet)
+ {
+ Iterator<T> itr;
+
+ map = new TreeMap<T, String>
+ ((Comparator<? super T>)sortedSet.comparator());
+ itr = ((SortedSet<T>) sortedSet).iterator();
+ ((TreeMap<T, String>) map).putKeysLinear(itr, sortedSet.size());
+ }
+
+ /**
+ * This private constructor is used to implement the subSet() calls around
+ * a backing TreeMap.SubMap.
+ *
+ * @param backingMap the submap
+ */
+ private TreeSet(NavigableMap<T,String> backingMap)
+ {
+ map = backingMap;
+ }
+
+ /**
+ * Adds the spplied Object to the Set if it is not already in the Set;
+ * returns true if the element is added, false otherwise.
+ *
+ * @param obj the Object to be added to this Set
+ * @throws ClassCastException if the element cannot be compared with objects
+ * already in the set
+ */
+ public boolean add(T obj)
+ {
+ return map.put(obj, "") == null;
+ }
+
+ /**
+ * Adds all of the elements in the supplied Collection to this TreeSet.
+ *
+ * @param c The collection to add
+ * @return true if the Set is altered, false otherwise
+ * @throws NullPointerException if c is null
+ * @throws ClassCastException if an element in c cannot be compared with
+ * objects already in the set
+ */
+ public boolean addAll(Collection<? extends T> c)
+ {
+ boolean result = false;
+ int pos = c.size();
+ Iterator<? extends T> itr = c.iterator();
+ while (--pos >= 0)
+ result |= (map.put(itr.next(), "") == null);
+ return result;
+ }
+
+ /**
+ * Removes all elements in this Set.
+ */
+ public void clear()
+ {
+ map.clear();
+ }
+
+ /**
+ * Returns a shallow copy of this Set. The elements are not cloned.
+ *
+ * @return the cloned set
+ */
+ public Object clone()
+ {
+ TreeSet<T> copy = null;
+ try
+ {
+ copy = (TreeSet<T>) super.clone();
+ // Map may be either TreeMap or TreeMap.SubMap, hence the ugly casts.
+ copy.map = (NavigableMap<T, String>) ((AbstractMap<T, String>) map).clone();
+ }
+ catch (CloneNotSupportedException x)
+ {
+ // Impossible result.
+ }
+ return copy;
+ }
+
+ /**
+ * Returns this Set's comparator.
+ *
+ * @return the comparator, or null if the set uses natural ordering
+ */
+ public Comparator<? super T> comparator()
+ {
+ return map.comparator();
+ }
+
+ /**
+ * Returns true if this Set contains the supplied Object, false otherwise.
+ *
+ * @param obj the Object to check for
+ * @return true if it is in the set
+ * @throws ClassCastException if obj cannot be compared with objects
+ * already in the set
+ */
+ public boolean contains(Object obj)
+ {
+ return map.containsKey(obj);
+ }
+
+ /**
+ * Returns the first (by order) element in this Set.
+ *
+ * @return the first element
+ * @throws NoSuchElementException if the set is empty
+ */
+ public T first()
+ {
+ return map.firstKey();
+ }
+
+ /**
+ * Returns a view of this Set including all elements less than
+ * <code>to</code>. The returned set is backed by the original, so changes
+ * in one appear in the other. The subset will throw an
+ * {@link IllegalArgumentException} for any attempt to access or add an
+ * element beyond the specified cutoff. The returned set does not include
+ * the endpoint; if you want inclusion, pass the successor element or
+ * call {@link #headSet(T,boolean)}. This call is equivalent to
+ * <code>headSet(to, false)</code>.
+ *
+ * @param to the (exclusive) cutoff point
+ * @return a view of the set less than the cutoff
+ * @throws ClassCastException if <code>to</code> is not compatible with
+ * the comparator (or is not Comparable, for natural ordering)
+ * @throws NullPointerException if to is null, but the comparator does not
+ * tolerate null elements
+ */
+ public SortedSet<T> headSet(T to)
+ {
+ return headSet(to, false);
+ }
+
+ /**
+ * Returns a view of this Set including all elements less than
+ * (or equal to, if <code>inclusive</code> is true) <code>to</code>.
+ * The returned set is backed by the original, so changes
+ * in one appear in the other. The subset will throw an
+ * {@link IllegalArgumentException} for any attempt to access or add an
+ * element beyond the specified cutoff.
+ *
+ * @param to the cutoff point
+ * @param inclusive true if <code>to</code> should be included.
+ * @return a view of the set for the specified range.
+ * @throws ClassCastException if <code>to</code> is not compatible with
+ * the comparator (or is not Comparable, for natural ordering)
+ * @throws NullPointerException if to is null, but the comparator does not
+ * tolerate null elements
+ */
+ public NavigableSet<T> headSet(T to, boolean inclusive)
+ {
+ return new TreeSet<T>(map.headMap(to, inclusive));
+ }
+
+ /**
+ * Returns true if this Set has size 0, false otherwise.
+ *
+ * @return true if the set is empty
+ */
+ public boolean isEmpty()
+ {
+ return map.isEmpty();
+ }
+
+ /**
+ * Returns in Iterator over the elements in this TreeSet, which traverses
+ * in ascending order.
+ *
+ * @return an iterator
+ */
+ public Iterator<T> iterator()
+ {
+ return map.keySet().iterator();
+ }
+
+ /**
+ * Returns the last (by order) element in this Set.
+ *
+ * @return the last element
+ * @throws NoSuchElementException if the set is empty
+ */
+ public T last()
+ {
+ return map.lastKey();
+ }
+
+ /**
+ * If the supplied Object is in this Set, it is removed, and true is
+ * returned; otherwise, false is returned.
+ *
+ * @param obj the Object to remove from this Set
+ * @return true if the set was modified
+ * @throws ClassCastException if obj cannot be compared to set elements
+ */
+ public boolean remove(Object obj)
+ {
+ return map.remove(obj) != null;
+ }
+
+ /**
+ * Returns the number of elements in this Set
+ *
+ * @return the set size
+ */
+ public int size()
+ {
+ return map.size();
+ }
+
+ /**
+ * Returns a view of this Set including all elements greater or equal to
+ * <code>from</code> and less than <code>to</code> (a half-open interval).
+ * The returned set is backed by the original, so changes in one appear in
+ * the other. The subset will throw an {@link IllegalArgumentException}
+ * for any attempt to access or add an element beyond the specified cutoffs.
+ * The returned set includes the low endpoint but not the high; if you want
+ * to reverse this behavior on either end, pass in the successor element
+ * or call {@link #subSet(T,boolean,T,boolean)}. This is equivalent to
+ * calling <code>subSet(from,true,to,false)</code>.
+ *
+ * @param from the (inclusive) low cutoff point
+ * @param to the (exclusive) high cutoff point
+ * @return a view of the set between the cutoffs
+ * @throws ClassCastException if either cutoff is not compatible with
+ * the comparator (or is not Comparable, for natural ordering)
+ * @throws NullPointerException if from or to is null, but the comparator
+ * does not tolerate null elements
+ * @throws IllegalArgumentException if from is greater than to
+ */
+ public SortedSet<T> subSet(T from, T to)
+ {
+ return subSet(from, true, to, false);
+ }
+
+ /**
+ * Returns a view of this Set including all elements greater than (or equal to,
+ * if <code>fromInclusive</code> is true</code> <code>from</code> and less than
+ * (or equal to, if <code>toInclusive</code> is true) <code>to</code>.
+ * The returned set is backed by the original, so changes in one appear in
+ * the other. The subset will throw an {@link IllegalArgumentException}
+ * for any attempt to access or add an element beyond the specified cutoffs.
+ *
+ * @param from the low cutoff point
+ * @param fromInclusive true if <code>from</code> should be included.
+ * @param to the high cutoff point
+ * @param toInclusive true if <code>to</code> should be included.
+ * @return a view of the set for the specified range.
+ * @throws ClassCastException if either cutoff is not compatible with
+ * the comparator (or is not Comparable, for natural ordering)
+ * @throws NullPointerException if from or to is null, but the comparator
+ * does not tolerate null elements
+ * @throws IllegalArgumentException if from is greater than to
+ */
+ public NavigableSet<T> subSet(T from, boolean fromInclusive,
+ T to, boolean toInclusive)
+ {
+ return new TreeSet<T>(map.subMap(from, fromInclusive,
+ to, toInclusive));
+ }
+
+ /**
+ * Returns a view of this Set including all elements greater or equal to
+ * <code>from</code>. The returned set is backed by the original, so
+ * changes in one appear in the other. The subset will throw an
+ * {@link IllegalArgumentException} for any attempt to access or add an
+ * element beyond the specified cutoff. The returned set includes the
+ * endpoint; if you want to exclude it, pass in the successor element
+ * or call {@link #tailSet(T,boolean)}. This is equivalent to calling
+ * <code>tailSet(from, true)</code>.
+ *
+ * @param from the (inclusive) low cutoff point
+ * @return a view of the set above the cutoff
+ * @throws ClassCastException if <code>from</code> is not compatible with
+ * the comparator (or is not Comparable, for natural ordering)
+ * @throws NullPointerException if from is null, but the comparator
+ * does not tolerate null elements
+ */
+ public SortedSet<T> tailSet(T from)
+ {
+ return tailSet(from, true);
+ }
+
+ /**
+ * Returns a view of this Set including all elements greater (or equal to,
+ * if <code>inclusive</code> is true) <code>from</code>. The returned set
+ * is backed by the original, so changes in one appear in the other. The
+ * subset will throw an {@link IllegalArgumentException} for any attempt
+ * to access or add an element beyond the specified cutoff.
+ *
+ * @param from the low cutoff point.
+ * @param inclusive true if <code>from</code> should be included.
+ * @return a view of the set for the specified range.
+ * @throws ClassCastException if <code>from</code> is not compatible with
+ * the comparator (or is not Comparable, for natural ordering)
+ * @throws NullPointerException if from is null, but the comparator
+ * does not tolerate null elements
+ */
+ public NavigableSet<T> tailSet(T from, boolean inclusive)
+ {
+ return new TreeSet<T>(map.tailMap(from, inclusive));
+ }
+
+ /**
+ * Serializes this object to the given stream.
+ *
+ * @param s the stream to write to
+ * @throws IOException if the underlying stream fails
+ * @serialData the <i>comparator</i> (Object), followed by the set size
+ * (int), the the elements in sorted order (Object)
+ */
+ private void writeObject(ObjectOutputStream s) throws IOException
+ {
+ s.defaultWriteObject();
+ Iterator<T> itr = map.keySet().iterator();
+ int pos = map.size();
+ s.writeObject(map.comparator());
+ s.writeInt(pos);
+ while (--pos >= 0)
+ s.writeObject(itr.next());
+ }
+
+ /**
+ * Deserializes this object from the given stream.
+ *
+ * @param s the stream to read from
+ * @throws ClassNotFoundException if the underlying stream fails
+ * @throws IOException if the underlying stream fails
+ * @serialData the <i>comparator</i> (Object), followed by the set size
+ * (int), the the elements in sorted order (Object)
+ */
+ private void readObject(ObjectInputStream s)
+ throws IOException, ClassNotFoundException
+ {
+ s.defaultReadObject();
+ Comparator<? super T> comparator = (Comparator<? super T>) s.readObject();
+ int size = s.readInt();
+ map = new TreeMap<T, String>(comparator);
+ ((TreeMap<T, String>) map).putFromObjStream(s, size, false);
+ }
+
+ /**
+ * Returns the least or lowest element in the set greater than or
+ * equal to the given element, or <code>null</code> if there is
+ * no such element.
+ *
+ * @param e the element relative to the returned element.
+ * @return the least element greater than or equal
+ * to the given element, or <code>null</code> if there is
+ * no such element.
+ * @throws ClassCastException if the specified element can not
+ * be compared with those in the map.
+ * @throws NullPointerException if the element is <code>null</code>
+ * and this set either uses natural
+ * ordering or a comparator that does
+ * not permit null elements.
+ * @since 1.6
+ */
+ public T ceiling(T e)
+ {
+ return map.ceilingKey(e);
+ }
+
+ /**
+ * Returns an iterator over the elements of this set in descending
+ * order. This is equivalent to calling
+ * <code>descendingSet().iterator()</code>.
+ *
+ * @return an iterator over the elements in descending order.
+ * @since 1.6
+ */
+ public Iterator<T> descendingIterator()
+ {
+ return descendingSet().iterator();
+ }
+
+ /**
+ * Returns a view of the set in reverse order. The descending set
+ * is backed by the original set, so that changes affect both sets.
+ * Any changes occurring to either set while an iteration is taking
+ * place (with the exception of a {@link Iterator#remove()} operation)
+ * result in undefined behaviour from the iteration. The ordering
+ * of the descending set is the same as for a set with a
+ * {@link Comparator} given by {@link Collections#reverseOrder()},
+ * and calling {@link #descendingSet()} on the descending set itself
+ * results in a view equivalent to the original set.
+ *
+ * @return a reverse order view of the set.
+ * @since 1.6
+ */
+ public NavigableSet<T> descendingSet()
+ {
+ return map.descendingKeySet();
+ }
+
+ /**
+ * Returns the greatest or highest element in the set less than or
+ * equal to the given element, or <code>null</code> if there is
+ * no such element.
+ *
+ * @param e the element relative to the returned element.
+ * @return the greatest element less than or equal
+ * to the given element, or <code>null</code> if there is
+ * no such element.
+ * @throws ClassCastException if the specified element can not
+ * be compared with those in the map.
+ * @throws NullPointerException if the element is <code>null</code>
+ * and this set either uses natural
+ * ordering or a comparator that does
+ * not permit null elements.
+ * @since 1.6
+ */
+ public T floor(T e)
+ {
+ return map.floorKey(e);
+ }
+
+ /**
+ * Returns the least or lowest element in the set strictly greater
+ * than the given element, or <code>null</code> if there is
+ * no such element.
+ *
+ * @param e the element relative to the returned element.
+ * @return the least element greater than
+ * the given element, or <code>null</code> if there is
+ * no such element.
+ * @throws ClassCastException if the specified element can not
+ * be compared with those in the map.
+ * @throws NullPointerException if the element is <code>null</code>
+ * and this set either uses natural
+ * ordering or a comparator that does
+ * not permit null elements.
+ * @since 1.6
+ */
+ public T higher(T e)
+ {
+ return map.higherKey(e);
+ }
+
+ /**
+ * Returns the greatest or highest element in the set strictly less
+ * than the given element, or <code>null</code> if there is
+ * no such element.
+ *
+ * @param e the element relative to the returned element.
+ * @return the greatest element less than
+ * the given element, or <code>null</code> if there is
+ * no such element.
+ * @throws ClassCastException if the specified element can not
+ * be compared with those in the map.
+ * @throws NullPointerException if the element is <code>null</code>
+ * and this set either uses natural
+ * ordering or a comparator that does
+ * not permit null elements.
+ * @since 1.6
+ */
+ public T lower(T e)
+ {
+ return map.lowerKey(e);
+ }
+
+ /**
+ * Removes and returns the least or lowest element in the set,
+ * or <code>null</code> if the map is empty.
+ *
+ * @return the removed first element, or <code>null</code> if the
+ * map is empty.
+ * @since 1.6
+ */
+ public T pollFirst()
+ {
+ return map.pollFirstEntry().getKey();
+ }
+
+ /**
+ * Removes and returns the greatest or highest element in the set,
+ * or <code>null</code> if the map is empty.
+ *
+ * @return the removed last element, or <code>null</code> if the
+ * map is empty.
+ * @since 1.6
+ */
+ public T pollLast()
+ {
+ return map.pollLastEntry().getKey();
+ }
+
+}