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// -*- C++ -*-

// Copyright (C) 2005 Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library 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, 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 General Public License for more details.

// You should have received a copy of the GNU General Public License along

// with this library; see the file COPYING.  If not, write to the Free

// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// USA.

// As a special exception, you may use this file as part of a free software

// library without restriction.  Specifically, if other files instantiate

// templates or use macros or inline functions from this file, or you compile

// this file and link it with other files to produce an executable, this

// file does not by itself cause the resulting executable to be covered by

// the GNU General Public License.  This exception does not however

// invalidate any other reasons why the executable file might be covered by

// the GNU General Public License.

// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.

// Permission to use, copy, modify, sell, and distribute this software

// is hereby granted without fee, provided that the above copyright

// notice appears in all copies, and that both that copyright notice and

// this permission notice appear in supporting documentation. None of

// the above authors, nor IBM Haifa Research Laboratories, make any

// representation about the suitability of this software for any

// purpose. It is provided "as is" without express or implied warranty.

/**

 * @file hash_load_set_change_example.cpp

 * An example of setting and changing the load factor of a hash-based

 *      container object.

 */

// For cc_hash_assoc_cntnr.

#include <ext/pb_assoc/assoc_cntnr.hpp>

/*

 * For hash_standard_resize_policy, hash_exponential_size_policy,

 *      and direct_mask_range_hashing.

 */

#include <ext/pb_assoc/hash_policy.hpp>

// For unary_function.

#include <functional>

// For assert

#include <cassert>

/*

 * A simple hash functor.

 *      std::hash could serve instead of this functor,

 *      but it is not yet standard everywhere.

 */

struct int_hash : public std::unary_function<

  int,

             size_t>

{

  inline size_t

  operator()(int i) const

  {

    return (i);

  }

};

int

main()

{

  // A trigger policy type.

  typedef pb_assoc::hash_load_check_resize_trigger< true> trigger_t;

  // A resize policy type.

  typedef

    pb_assoc::hash_standard_resize_policy<

    pb_assoc::hash_exponential_size_policy<>,

    // Trigger type.

    trigger_t,

    /* Allow external access to size.

     *  This is not necessary for setting the load factor,

     *  but it allows to call get_actual_size.

     */

    true>

    resize_t;

  /*

   * A collision-chaining hash table mapping ints to chars.

   */

  typedef

    pb_assoc::cc_hash_assoc_cntnr<

    int,

    char,

    int_hash,

    std::equal_to<int>,

    // Combining function.

    pb_assoc::direct_mask_range_hashing<>,

    // Resize policy.

    resize_t>

    map_t;

  // A trigger policy object with load between 0.3 and 0.8.

  trigger_t trigger(static_cast<float>(0.3), static_cast<float>(0.8));

  // A resize policy object with the above trigger.

  resize_t resize(pb_assoc::hash_exponential_size_policy<>(),

                  trigger);

  map_t c(int_hash(),

          std::equal_to<int>(),

          pb_assoc::direct_mask_range_hashing<>(),

          resize);

  c[1] = 'a';

  // Check the loads and sizes.

  assert(c.get_loads().first == static_cast<float>(0.3));

  assert(c.get_loads().second == static_cast<float>(0.8));

  assert(c.get_actual_size() == 8);

  assert(c.size() == 1);

  /*

   * Note that there is a discrepancy between the loads of the policy

   *    object and the actual size of the container object. This is

   *    because the container's construction performs an implicit external

   *    resize.

   */

  c[2] = 'b';

  c[3] = 'c';

  c[4] = 'd';

  assert(c.get_actual_size() == 8);

  // Change the loads. This causes (potentially) a resize.

  c.set_loads(std::make_pair(

                             static_cast<float>(0.01),

                             static_cast<float>(0.05)));

  // The loads actually changed.

  assert(c.get_actual_size() > 8);

}