/*******************************************************************************
* Breakout Cave Survey Visualizer
*
* Copyright (C) 2014 James Edwards
*
* jedwards8 at fastmail dot fm
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option) any later
* version.
*
* This program 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 General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*******************************************************************************/
package org.andork.func;
import java.util.IdentityHashMap;
/**
* A {@link Mapper} whose {@link #map(Object)} and {@link #unmap(Object)}
* methods will return the same values for the same parameters, even if the
* wrapped {@link Mapper} returns different (but equal) values for the same
* parameters.
*
* @author andy.edwards
*/
public class IdentityHashMapMapper<I, O> implements Mapper<I, O> {
private final Mapper<I, O> wrapped;
private final IdentityHashMap<I, O> inToOut = new IdentityHashMap<I, O>();
public IdentityHashMapMapper(Mapper<I, O> wrapped) {
this.wrapped = wrapped;
}
@Override
public O map(I in) {
O result = inToOut.get(in);
if (result == null) {
inToOut.put(in, result = wrapped.map(in));
}
return result;
}
}