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 Nov 8, 2009 */

    12 

    13 package clojure.lang;

    14 

    15 public final class MethodImplCache{

    16 

    17 static public class Entry{

    18 	final public Class c;

    19 	final public IFn fn;

    20 

    21 	public Entry(Class c, IFn fn){

    22 		this.c = c;

    23 		this.fn = fn;

    24 	}

    25 }

    26 

    27 public final IPersistentMap protocol;

    28 public final Keyword methodk;

    29 public final int shift;

    30 public final int mask;

    31 public final Object[] table;    //[class, entry. class, entry ...]

    32 

    33 volatile Entry mre = null;

    34 

    35 public MethodImplCache(IPersistentMap protocol, Keyword methodk){

    36 	this(protocol, methodk, 0, 0, RT.EMPTY_ARRAY);

    37 }

    38 

    39 public MethodImplCache(IPersistentMap protocol, Keyword methodk, int shift, int mask, Object[] table){

    40 	this.protocol = protocol;

    41 	this.methodk = methodk;

    42 	this.shift = shift;

    43 	this.mask = mask;

    44 	this.table = table;

    45 }

    46 

    47 public IFn fnFor(Class c){

    48 	Entry last = mre;

    49 	if(last != null && last.c == c)

    50 		return last.fn;

    51 	return findFnFor(c);

    52 }

    53 

    54 IFn findFnFor(Class c){

    55 	int idx = ((Util.hash(c) >> shift) & mask) << 1;

    56 	if(idx < table.length && table[idx] == c)

    57 		{

    58 		Entry e = ((Entry) table[idx + 1]);

    59 		mre = e;

    60 		return  e != null ? e.fn : null;

    61 		}

    62 	return null;

    63 }

    64 

    65 

    66 }
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 21 Aug 2010 06:25:44 -0400
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