Mercurial > lasercutter

     1 /**

     2  *   Copyright (c) Rich Hickey. All rights reserved.

     3  *   The use and distribution terms for this software are covered by the

     4  *   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)

     5  *   which can be found in the file epl-v10.html at the root of this distribution.

     6  *   By using this software in any fashion, you are agreeing to be bound by

     7  * 	 the terms of this license.

     8  *   You must not remove this notice, or any other, from this software.

     9  **/

    10 

    11 /* rich Jan 1, 2009 */

    12 

    13 package clojure.lang;

    14 

    15 import java.util.concurrent.atomic.AtomicReference;

    16 

    17 final public class Atom extends ARef{

    18 final AtomicReference state;

    19 

    20 public Atom(Object state){

    21 	this.state = new AtomicReference(state);

    22 }

    23 

    24 public Atom(Object state, IPersistentMap meta){

    25 	super(meta);

    26 	this.state = new AtomicReference(state);

    27 }

    28 

    29 public Object deref(){

    30 	return state.get();

    31 }

    32 

    33 public Object swap(IFn f) throws Exception{

    34 	for(; ;)

    35 		{

    36 		Object v = deref();

    37 		Object newv = f.invoke(v);

    38 		validate(newv);

    39 		if(state.compareAndSet(v, newv))

    40 			{

    41 			notifyWatches(v, newv);

    42 			return newv;

    43 			}

    44 		}

    45 }

    46 

    47 public Object swap(IFn f, Object arg) throws Exception{

    48 	for(; ;)

    49 		{

    50 		Object v = deref();

    51 		Object newv = f.invoke(v, arg);

    52 		validate(newv);

    53 		if(state.compareAndSet(v, newv))

    54 			{

    55 			notifyWatches(v, newv);

    56 			return newv;

    57 			}

    58 		}

    59 }

    60 

    61 public Object swap(IFn f, Object arg1, Object arg2) throws Exception{

    62 	for(; ;)

    63 		{

    64 		Object v = deref();

    65 		Object newv = f.invoke(v, arg1, arg2);

    66 		validate(newv);

    67 		if(state.compareAndSet(v, newv))

    68 			{

    69 			notifyWatches(v, newv);

    70 			return newv;

    71 			}

    72 		}

    73 }

    74 

    75 public Object swap(IFn f, Object x, Object y, ISeq args) throws Exception{

    76 	for(; ;)

    77 		{

    78 		Object v = deref();

    79 		Object newv = f.applyTo(RT.listStar(v, x, y, args));

    80 		validate(newv);

    81 		if(state.compareAndSet(v, newv))

    82 			{

    83 			notifyWatches(v, newv);

    84 			return newv;

    85 			}

    86 		}

    87 }

    88 

    89 public boolean compareAndSet(Object oldv, Object newv){

    90 	validate(newv);

    91 	boolean ret = state.compareAndSet(oldv, newv);

    92 	if(ret)

    93 		notifyWatches(oldv, newv);

    94 	return ret;

    95 }

    96 

    97 public Object reset(Object newval){

    98 	Object oldval = state.get();

    99 	validate(newval);

   100 	state.set(newval);

   101 	notifyWatches(oldval, newval);

   102 	return newval;

   103 }

   104 }
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 21 Aug 2010 06:25:44 -0400
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