old-autovect-branch/libstdc++-v3/testsuite/ext/pb_assoc/example/hash_initial_size.cc

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 2, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  31
  32 // Permission to use, copy, modify, sell, and distribute this software
  33 // is hereby granted without fee, provided that the above copyright
  34 // notice appears in all copies, and that both that copyright notice and
  35 // this permission notice appear in supporting documentation. None of
  36 // the above authors, nor IBM Haifa Research Laboratories, make any
  37 // representation about the suitability of this software for any
  38 // purpose. It is provided "as is" without express or implied warranty.
  39
  40 /**
  41  * @file gp_ht_map_resize_example.cpp
  42  * An example of setting an initial size for a container object.
  43  */
  44
  45 // For gp_hash_assoc_cntnr
  46 #include <ext/pb_assoc/assoc_cntnr.hpp>
  47 // For hash-related policies.
  48 #include <ext/pb_assoc/hash_policy.hpp>
  49 // For assert
  50 #include <cassert>
  51
  52 /*
  53  * A simple hash functor.
  54  *      std::hash could serve instead of this functor,
  55  *      but it is not yet standard everywhere.
  56  */
  57 struct int_hash : public std::unary_function<
  58   int,
  59              size_t>
  60 {
  61   inline size_t
  62   operator()(const int& r_i) const
  63   {
  64     return (r_i);
  65   }
  66 };
  67
  68 int
  69 main()
  70 {
  71   // Resize policy type.
  72   typedef
  73     pb_assoc::hash_standard_resize_policy<
  74     // Size-policy type.
  75     pb_assoc::hash_exponential_size_policy<>,
  76     // Trigger-policy type.
  77     pb_assoc::hash_load_check_resize_trigger<>,
  78     /* Allow external access to size.
  79      *  This is just used in this example for using the
  80      *  get_actual_size method (which won't be accessible without
  81      *  this flag.
  82      */
  83     true>
  84     resize_policy_t;
  85
  86   /*
  87    * A collision-probing hash table mapping ints to chars.
  88    */
  89   typedef
  90     pb_assoc::gp_hash_assoc_cntnr<
  91     int,
  92     char,
  93     int_hash,
  94     std::equal_to<
  95     int>,
  96     // Combining function.
  97     pb_assoc::direct_mask_range_hashing<>,
  98     // Probe function.
  99     pb_assoc::linear_probe_fn<
 100     const int& >,
 101     // Resize policy.
 102     resize_policy_t>
 103     map_t;
 104
 105   // A resize-policy object with suggested initial size 256.
 106   resize_policy_t res(pb_assoc::hash_exponential_size_policy<>(256));
 107
 108   map_t g(int_hash(),
 109           std::equal_to<int>(),
 110           pb_assoc::direct_mask_range_hashing<>(),
 111           pb_assoc::linear_probe_fn<const int& >(),
 112           res);
 113
 114   /*
 115    * Check the actual size of the container object. In this case,
 116    *    this should be the initial size given by the size policy object.
 117    **/
 118   assert(g.get_actual_size() >= 256);
 119
 120   assert(g.size() == 0);
 121 }
 122