clojure.lang.Delay Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of clojure Show documentation

Clojure core environment and runtime library.

The newest version!

/**
 *   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 Jun 28, 2007 */

package clojure.lang;

public class Delay implements IDeref, IPending{
Object val;
Throwable exception;
IFn fn;

public Delay(IFn fn){
	this.fn = fn;
	this.val = null;
        this.exception = null;
}

static public Object force(Object x) {
	return (x instanceof Delay) ?
	       ((Delay) x).deref()
	       : x;
}

synchronized public Object deref() {
	if(fn != null)
		{
		try
			{
			val = fn.invoke();
			}
		catch(Throwable t)
			{
			exception = t;
			}
		fn = null;
		}
	if(exception != null)
		throw Util.sneakyThrow(exception);
	return val;
}

synchronized public boolean isRealized(){
	return fn == null;
}
}