/**

* 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.io.IOException;

import java.io.NotSerializableException;

import java.util.Enumeration;

public class EnumerationSeq extends ASeq{

private static final long serialVersionUID = 5227192199685595994L;

final Enumeration iter;

final State state;

static class State{

volatile Object val;

volatile Object _rest;

}

public static EnumerationSeq create(Enumeration iter){

if(iter.hasMoreElements())

return new EnumerationSeq(iter);

return null;

}

EnumerationSeq(Enumeration iter){

this.iter = iter;

state = new State();

this.state.val = state;

this.state._rest = state;

}

EnumerationSeq(IPersistentMap meta, Enumeration iter, State state){

super(meta);

this.iter = iter;

this.state = state;

}

public Object first(){

if(state.val == state)

synchronized(state)

{

if(state.val == state)

state.val = iter.nextElement();

}

return state.val;

}

public ISeq next(){

if(state._rest == state)

synchronized(state)

{

if(state._rest == state)

{

first();

state._rest = create(iter);

}

}

return (ISeq) state._rest;

}

public EnumerationSeq withMeta(IPersistentMap meta){

if(meta() == meta)

return this;

return new EnumerationSeq(meta, iter, state);

}

private void writeObject (java.io.ObjectOutputStream out) throws IOException {

throw new NotSerializableException(getClass().getName());

}

}