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// Copyright (c) 2004-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc.
//
// MySQL Connector/NET is licensed under the terms of the GPLv2
// <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most
// MySQL Connectors. There are special exceptions to the terms and
// conditions of the GPLv2 as it is applied to this software, see the
// FLOSS License Exception
// <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
//
// 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; version 2 of the License.
//
// 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 St, Fifth Floor, Boston, MA 02110-1301 USA
using System;
using System.Collections.Generic;
namespace MySql.Data.Common
{
internal class Cache<KeyType, ValueType>
{
private int _capacity;
private Queue<KeyType> _keyQ;
private Dictionary<KeyType, ValueType> _contents;
public Cache(int initialCapacity, int capacity)
{
_capacity = capacity;
_contents = new Dictionary<KeyType, ValueType>(initialCapacity);
if (capacity > 0)
_keyQ = new Queue<KeyType>(initialCapacity);
}
public ValueType this[KeyType key]
{
get
{
ValueType val;
if (_contents.TryGetValue(key, out val))
return val;
else
return default(ValueType);
}
set { InternalAdd(key, value); }
}
public void Add(KeyType key, ValueType value)
{
InternalAdd(key, value);
}
private void InternalAdd(KeyType key, ValueType value)
{
if (!_contents.ContainsKey(key))
{
if (_capacity > 0)
{
_keyQ.Enqueue(key);
if (_keyQ.Count > _capacity)
_contents.Remove(_keyQ.Dequeue());
}
}
_contents[key] = value;
}
}
}
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