libstdc++-v3/testsuite/util/testsuite_rng.h

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006, 2008 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 terms
   7 // of the GNU General Public License as published by the Free Software
   8 // Foundation; either version 2, or (at your option) any later
   9 // version.
  10
  11 // This library is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // 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
  22 // software library without restriction.  Specifically, if other files
  23 // instantiate templates or use macros or inline functions from this
  24 // file, or you compile this file and link it with other files to
  25 // produce an executable, this file does not by itself cause the
  26 // resulting executable to be covered by the GNU General Public
  27 // License.  This exception does not however invalidate any other
  28 // reasons why the executable file might be covered by the GNU General
  29 // Public License.
  30
  31 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  32
  33 // Permission to use, copy, modify, sell, and distribute this software
  34 // is hereby granted without fee, provided that the above copyright
  35 // notice appears in all copies, and that both that copyright notice
  36 // and this permission notice appear in supporting documentation. None
  37 // of the above authors, nor IBM Haifa Research Laboratories, make any
  38 // representation about the suitability of this software for any
  39 // purpose. It is provided "as is" without express or implied
  40 // warranty.
  41
  42 /**
  43  * @file testsuite_rng.h
  44  */
  45
  46 #ifndef _GLIBCXX_TESTSUITE_RNG_H
  47 #define _GLIBCXX_TESTSUITE_RNG_H
  48
  49 #include <ctime>
  50 #include <climits>
  51 #include <debug/debug.h>
  52 #include <tr1/random>
  53
  54 namespace __gnu_pbds
  55 {
  56   namespace test
  57   {
  58     class twister_rand_gen
  59     {
  60     public:
  61       twister_rand_gen(unsigned int seed =
  62                        static_cast<unsigned int>(std::time(0)))
  63       : m_base_generator(seed)
  64       {
  65         // Do nothing.
  66       }
  67
  68       void
  69       init(unsigned int seed)
  70       { m_base_generator.seed(seed); }
  71
  72       static unsigned int
  73       get_time_determined_seed()
  74       { return(static_cast<unsigned int>(std::time(0))); }
  75
  76       unsigned long
  77       get_unsigned_long(unsigned long min = 0,
  78                         unsigned long max = UINT_MAX - 1)
  79       {
  80         _GLIBCXX_DEBUG_ASSERT(max >= min);
  81         const double prob = get_prob();
  82         const unsigned long r = (unsigned long)((max - min + 1) * prob) + min;
  83         _GLIBCXX_DEBUG_ASSERT(r <= max);
  84         return r;
  85       }
  86
  87       double
  88       get_prob()
  89       {
  90         const double min = m_base_generator.min();
  91         const double max = m_base_generator.max();
  92         const double range = static_cast<const double>(max - min);
  93         const double res = static_cast<const double>(m_base_generator() - min);
  94         const double ret = res / range;
  95         _GLIBCXX_DEBUG_ASSERT(ret >= 0 && ret <= 1);
  96         return ret;
  97       }
  98
  99     private:
 100       typedef std::tr1::mt19937 base_generator_t;
 101
 102       base_generator_t m_base_generator;
 103     };
 104   } // namespace test
 105 } // namespace __gnu_pbds
 106
 107 #endif // #ifndef _GLIBCXX_TESTSUITE_RNG_H