/* * Distributed as part of c3p0 v.0.9.1-pre6 * * Copyright (C) 2005 Machinery For Change, Inc. * * Author: Steve Waldman <swaldman@mchange.com> * * This library is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License version 2.1, as  * published by the Free Software Foundation. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this software; see the file LICENSE.  If not, write to the * Free Software Foundation, Inc., 59 Temple Place, Suite 330, * Boston, MA 02111-1307, USA. */package com.mchange.v2.coalesce;public final class CoalescerFactory{    /**     *  <p>Creates a "Coalescer" that coalesces Objects according to their     *  equals() method. Given a set of n Objects among whom equals() would     *  return true, calling coalescer.coalesce() in any order on any sequence      *  of these Objects will always return a single "canonical" instance.</p>     *     *  <p>This method creates a weak, synchronized coalesecer, safe for use     *  by multiple Threads.</p>     */    public static Coalescer createCoalescer()    { return createCoalescer( true, true ); }    /**     *  <p>Creates a "Coalescer" that coalesces Objects according to their     *  equals() method. Given a set of n Objects among whom equals() would     *  return true, calling coalescer.coalesce() in any order on any sequence      *  of these Objects will always return a single "canonical" instance.</p>     *     *  @param weak if true, the Coalescer will use WeakReferences to hold     *              its canonical instances, allowing them to be garbage     *              collected if they are nowhere in use.     *     *  @param synced if true, access to the Coalescer will be automatically     *                synchronized. if set to false, then users must manually     *                synchronize access.     */    public static Coalescer createCoalescer( boolean weak, boolean synced )    { return createCoalescer( null, weak, synced ); }    /**     *  <p>Creates a "Coalescer" that coalesces Objects according to the     *  checkCoalesce() method of a "CoalesceChecker". Given a set of      *  n Objects among whom calling cc.checkCoalesce() on any pair would     *  return true, calling coalescer.coalesce() in any order on any sequence      *  of these Objects will always return a single "canonical" instance.     *  This allows one to define immutable value Objects whose equals()      *  method is a mere identity test -- one can use a Coalescer in a      *  factory method to ensure that no two instances with the same values     *  are made available to clients.</p>     *     * @param cc CoalesceChecker that will be used to determine whether two     *           objects are equivalent and can be coalesced. [If cc is null, then two     *           objects will be coalesced iff o1.equals( o2 ).]     *     *  @param weak if true, the Coalescer will use WeakReferences to hold     *              its canonical instances, allowing them to be garbage     *              collected if they are nowhere in use.     *     *  @param synced if true, access to the Coalescer will be automatically     *                synchronized. if set to false, then users must manually     *                synchronize access.     */    public static Coalescer createCoalescer( CoalesceChecker cc, boolean weak, boolean synced )    {	Coalescer out;	if ( cc == null )	    {		out = ( weak ? 			(Coalescer) new WeakEqualsCoalescer() : 			(Coalescer) new StrongEqualsCoalescer() );	    }	else	    {		out = ( weak ? 			(Coalescer) new WeakCcCoalescer( cc ) : 			(Coalescer) new StrongCcCoalescer( cc ) );	    }	return ( synced ? new SyncedCoalescer( out ) : out );    }}