Cache.h++

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/* ---------------------------------------------------------------------------
   commonc++ - A C++ Common Class Library
   Copyright (C) 2005-2014  Mark A Lindner

   This file is part of commonc++.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   ---------------------------------------------------------------------------
*/

#ifndef __ccxx_Cache_hxx
#define __ccxx_Cache_hxx

#include <map>
#include <utility>

#include <commonc++/Common.h++>

namespace ccxx {

template<typename K, typename T> class Cache
{
 public:

  Cache(uint_t maxSize);

  virtual ~Cache();

  void put(K key, T* item);

  T* get(K key) const;

  inline T* operator[](K key) const
  { return(this->get(key)); }

  T* take(K key);

  bool remove(K key);

  bool contains(K key) const;

  void clear();

  inline uint_t getMaxSize() const
  { return(_maxSize); }

  inline uint_t getSize() const
  { return(_size); }

  inline bool isEmpty() const
  { return(_size == 0); }

 protected:

  virtual void onRemove(K key, T* item);

 private:

  uint_t _maxSize;
  uint_t _size;

  struct Link
  {
    Link(K key)
      : key(key),
        prev(NULL),
        next(NULL)
    { }

    K key;
    Link *prev;
    Link *next;
  };

  struct KeyCompare
  {
    bool operator()(const Link* key1, const Link* key2) const
    { return(key1->key < key2->key); }
  };
  void _unlink(Link* link) const;
  void _link(Link* link) const;

  typedef std::map<Link*, T*, KeyCompare> MapType;
  mutable MapType _map;
  mutable Link* _head;
  mutable Link* _tail;
};

#include <commonc++/CacheImpl.h++>

} // namespace ccxx

#endif // __ccxx_Cache_hxx