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// -*- C++ -*-

// Copyright (C) 2005, 2006, 2009 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 3, 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 COPYING3.  If not see

// <http://www.gnu.org/licenses/>.

// 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_resize_example.cpp

 * An example of externally resizing a map.

 */

/**

 * This example shows how to externally manipulate the size of a hash-based

 * container object throught its resize-policy object.

 **/

#include <functional>

#include <cassert>

#include <ext/pb_ds/assoc_container.hpp>

#include <ext/pb_ds/hash_policy.hpp>

using namespace std;

using namespace __gnu_pbds;

// A simple hash functor.

// hash could serve instead of this functor, but it is not yet

// standard everywhere.

struct int_hash : public unary_function<int, size_t>

{

  inline size_t

  operator()(const int& r_i) const

  { return r_i; }

};

int main()

{

  // A probing hash table mapping ints to chars.

  typedef

    gp_hash_table<

    int,

    char,

    int_hash,

    equal_to<

    int>,

    // Combining function.

    direct_mask_range_hashing<>,

    // Probe function.

    linear_probe_fn<>,

    // Resize policy.

    hash_standard_resize_policy<

    hash_exponential_size_policy<>,

    hash_load_check_resize_trigger<>,

    /* Allow external access to size.

     * Without setting this to true, external resizing

     * is not possible.

     */

    true> >

    map_t;

  map_t g;

  // Check the actual size of the container object. In this case, this

  // should be the initial size given by the size policy object.

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

  // Insert some elements.

  g[1] = 'a';

  g[2] = 'b';

  g[3] = 'c';

  // Now resize the table upward.

  g.resize(200);

  // Check the actual size of the container object. 

  // For the policy used in this example, the nearest larger size than

  // 200 is 256.

  assert(g.get_actual_size() == 256);

  g[67] = 'g';

  g[22] = 'f';

  // Regardless of the internal size, the logical size should be 5.

  assert(g.size() == 5);

  // Now resize the table downward.

  g.resize(106);

  // Check the actual size of the container object. 

  // For the policy used in this example, the nearest larger size than

  // 106 is 128.

  assert(g.get_actual_size() == 128);

  g[37] = 'f';

  // Regardless of the internal size, the logical size should be 5.

  assert(g.size() == 6);

  return 0;

}