tpl_dynLhash.H

/*
  This file is part of Aleph system

  Copyright (c) 2002, 2003, 2004, 2005, 2006
  UNIVERSITY LOS ANDES (ULA) Merida - REPÚBLICA BOLIVARIANA DE VENEZUELA  

  - Center of Studies in Microelectronics & Distributed Systems (CEMISID) 
  - ULA Computer Science Department
  - FUNDACITE Mérida - Ministerio de Ciencia y Tecnología

  PERMISSION TO USE, COPY, MODIFY AND DISTRIBUTE THIS SOFTWARE AND ITS
  DOCUMENTATION IS HEREBY GRANTED, PROVIDED THAT BOTH THE COPYRIGHT
  NOTICE AND THIS PERMISSION NOTICE APPEAR IN ALL COPIES OF THE
  SOFTWARE, DERIVATIVE WORKS OR MODIFIED VERSIONS, AND ANY PORTIONS
  THEREOF, AND THAT BOTH NOTICES APPEAR IN SUPPORTING DOCUMENTATION.

  Aleph 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.

  UNIVERSIDAD DE LOS ANDES requests users of this software to return to 

  Leandro Leon
  CEMISID 
  Ed La Hechicera 
  3er piso, ala sur
  Facultad de Ingenieria 
  Universidad de Los Andes 
  Merida - REPÚBLICA BOLIVARIANA DE VENEZUELA    or

  lrleon@ula.ve

  any improvements or extensions that they make and grant Universidad 
  de Los Andes (ULA) the rights to redistribute these changes. 

  Aleph is (or was) granted by: 
  - Consejo de Desarrollo Cientifico, Humanistico, Tecnico de la ULA 
    (CDCHT)
  - Fundacite Mérida
*/


# ifndef TPL_DYNLHASH_H
# define TPL_DYNLHASH_H

# include <tpl_lhash.H>

using namespace Aleph;

namespace Aleph {

    template <typename Key, typename Record, class Cmp = Aleph::equal_to<Key> >
class DynLhashTable : public LhashTable<Key>
{

private:

  struct DLBucket : public LhashTable<Key>::Bucket
  {
    Record record;

    DLBucket(const Key & key, const Record & _record)
      : LhashTable<Key>::Bucket(key), record(_record)
    { /* Empty */ }
  };
  static DLBucket * record_to_bucket(Record * rec)
  {
    DLBucket * ret_val = 0;
    size_t offset = reinterpret_cast<size_t>(&ret_val->record);
    return reinterpret_cast<DLBucket*>(reinterpret_cast<size_t>(rec) - 
                                       offset);
  }
  class DLProxy
  {
    DynLhashTable & table;
    const Key &     key;
    DLBucket *      bucket;

  public:

    DLProxy(DynLhashTable & _table, const Key& _key)
      : table(_table), key(_key)
    {
      Record * record = table.search(key);
      bucket = record not_eq NULL ? record_to_bucket(record) : NULL;
    }

    operator const Record & () const throw(std::exception, std::invalid_argument)
    {
      if (bucket == NULL)
        throw std::invalid_argument("access to unexisting entry");
    
      return bucket->record;
    }

    DLProxy& operator = (const Record& record) 
      throw(std::exception, std::bad_alloc) 
    {
      if (bucket != NULL)
        {
          bucket->record = record;
          return *this;
        }

      bucket = new DLBucket (key, record);
      table.LhashTable<Key>::insert(bucket);

      return *this;
    }

    DLProxy& operator = (const DLProxy& proxy) 
      throw(std::exception, std::bad_alloc, std::invalid_argument)
    {
      if (proxy.bucket == NULL)
        throw std::invalid_argument("access to unexisting entry");

      if (bucket != NULL)
        {
          bucket->record = proxy.bucket->record;
          return *this;
        }

      bucket = new DLBucket (key, proxy.bucket->record);
      table.LhashTable<Key>::insert(bucket);

      return *this;
    }
  };

public:


  typedef typename DynLhashTable<Key, Record>::Hash_Fct Hash_Fct;

  DynLhashTable(Hash_Fct hash_fct, const size_t & len = DefaultPrime) 
    throw (std::exception, std::bad_alloc) : LhashTable<Key>(hash_fct, len)
  {
    // Empty 
  }


  Record * insert(const Key & key, const Record & record)

    throw (std::exception, std::bad_alloc)

  {
    DLBucket * bucket = new DLBucket (key, record);

    LhashTable<Key>::insert(bucket);

    return &bucket->record;
  }
  Record * search(const Key & key)
  {
    DLBucket * bucket = static_cast<DLBucket*>(LhashTable<Key>::search(key));

    return bucket != NULL ? &bucket->record : NULL;
  }
  void remove(Record * record)
  {
    DLBucket* bucket = record_to_bucket(record);

    LhashTable<Key>::remove(bucket);

    delete bucket;
  }
  DLProxy operator [] (const Key& key) const
    throw(std::exception, std::invalid_argument) 
  {
    return DLProxy ( const_cast<DynLhashTable&>(*this), key);
  }

  DLProxy operator [] (const Key& key) 
    throw(std::exception, std::bad_alloc, std::invalid_argument) 
  {
    return DLProxy (*this, key);
  }
};

} // end namespace Aleph

# endif // TPL_DYNLHASH_H

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