/* ***************************************************************************
 * Copyright (C) 2007 Jason House                                            *
 *                                                                           *
 * This file is part of HouseBot.                                            *
 *                                                                           *
 * HouseBot 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 3 of the License, or         *
 * (at your option) any later version.                                       *
 *                                                                           *
 * HouseBot 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, see <http://www.gnu.org/licenses/>.     *
 *                                                                           *
 *****************************************************************************/

/// Provides transposition table class
module search.transposition;

private{
	import tangoBind/*: bind*/;
	alias void delegate(Object) DisposeEvent;
	extern(C) void rt_attachDisposeEvent(Object obj, DisposeEvent event);
	extern(C) void rt_detachDisposeEvent(Object obj, DisposeEvent event);
	typedef size_t weakPointer;
	struct valueHolder(content_t){
		ulong key;
		weakPointer value;
		transpositionTable!(content_t) parent;
		void remove_(Object obj){
			parent.lookup.remove(key);
		}
	}
}

class transpositionTable(content_t){
private:
	valueHolder!(content_t)[ulong] lookup;
	content_t* castRealPointer(weakPointer p){
		return cast(content_t*)cast(void*)p;
	}
	weakPointer castWeakPointer(content_t* p){
		return cast(weakPointer)cast(void*)p;
	}
public:
	content_t* opIn(ulong key){
		valueHolder!(content_t)* ptr_ptr = (key in lookup);
		if (ptr_ptr is null)
			return null;
		else
			return castRealPointer((*ptr_ptr).value);
	}
	content_t opIndex(ulong key){
		return *castRealPointer(lookup[key].value);
	}
	void opIndexAssign(content_t value, ulong key){
		lookup[key] = valueHolder!(content_t)(key,castWeakPointer(&value),this);
		rt_attachDisposeEvent(value, &lookup[key].remove_);
	}
	void remove(ulong key){
		rt_detachDisposeEvent(*castRealPointer(lookup[key].value), &lookup[key].remove_);
		lookup.remove(key);
	}
}