code: /**
   *   Copyright (c) Rich Hickey. All rights reserved.
   *   The use and distribution terms for this software are covered by the
   *   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
   *   which can be found in the file epl-v10.html at the root of this distribution.
   *   By using this software in any fashion, you are agreeing to be bound by
   * 	 the terms of this license.
   *   You must not remove this notice, or any other, from this software.
   **/
  
  /* rich Mar 3, 2008 */
  
  package clojure.lang;
  
  import java.util.Comparator;
  
  public class PersistentTreeSet extends APersistentSet implements IObj, Reversible, Sorted{
  static public final PersistentTreeSet EMPTY = new PersistentTreeSet(null, PersistentTreeMap.EMPTY);
  final IPersistentMap _meta;
  
  
  static public PersistentTreeSet create(ISeq items){
  	PersistentTreeSet ret = EMPTY;
  	for(; items != null; items = items.next())
  		{
  		ret = (PersistentTreeSet) ret.cons(items.first());
  		}
  	return ret;
  }
  
  static public PersistentTreeSet create(Comparator comp, ISeq items){
  	PersistentTreeSet ret = new PersistentTreeSet(null, new PersistentTreeMap(null, comp));
  	for(; items != null; items = items.next())
  		{
  		ret = (PersistentTreeSet) ret.cons(items.first());
  		}
  	return ret;
  }
  
  PersistentTreeSet(IPersistentMap meta, IPersistentMap impl){
  	super(impl);
  	this._meta = meta;
  }
  
  public boolean equals(Object obj){
      try {
          return super.equals(obj);
      } catch (ClassCastException e) {
          return false;
      }
  }
  
  public boolean equiv(Object obj){
      try {
          return super.equiv(obj);
      } catch (ClassCastException e) {
          return false;
      }
  }
  
  public IPersistentSet disjoin(Object key) {
  	if(contains(key))
  		return new PersistentTreeSet(meta(),impl.without(key));
  	return this;
  }
  
  public IPersistentSet cons(Object o){
  	if(contains(o))
  		return this;
  	return new PersistentTreeSet(meta(),impl.assoc(o,o));
  }
  
  public IPersistentCollection empty(){
  	return new PersistentTreeSet(meta(),(PersistentTreeMap)impl.empty());
  }
  
  public ISeq rseq() {
  	return APersistentMap.KeySeq.create(((Reversible) impl).rseq());
  }
  
  public PersistentTreeSet withMeta(IPersistentMap meta){
  	if(meta() == meta)
  		return this;
  	return new PersistentTreeSet(meta, impl);
  }
  
  public Comparator comparator(){
  	return ((Sorted)impl).comparator();
  }
  
  public Object entryKey(Object entry){
  	return entry;
  }
  
  public ISeq seq(boolean ascending){
  	PersistentTreeMap m = (PersistentTreeMap) impl;
  	return RT.keys(m.seq(ascending));
  }
  
  public ISeq seqFrom(Object key, boolean ascending){
  	PersistentTreeMap m = (PersistentTreeMap) impl;
  	return RT.keys(m.seqFrom(key,ascending));
  }
  
  public IPersistentMap meta(){
  	return _meta;
  }
  }
  