ceph/src/boost/libs/random/include/boost/random/random_number_generator.hpp

   1 /* boost random/random_number_generator.hpp header file
   2  *
   3  * Copyright Jens Maurer 2000-2001
   4  * Distributed under the Boost Software License, Version 1.0. (See
   5  * accompanying file LICENSE_1_0.txt or copy at
   6  * http://www.boost.org/LICENSE_1_0.txt)
   7  *
   8  * See http://www.boost.org for most recent version including documentation.
   9  *
  10  * $Id$
  11  *
  12  * Revision history
  13  *  2001-02-18  moved to individual header files
  14  */
  15
  16 #ifndef BOOST_RANDOM_RANDOM_NUMBER_GENERATOR_HPP
  17 #define BOOST_RANDOM_RANDOM_NUMBER_GENERATOR_HPP
  18
  19 #include <boost/assert.hpp>
  20 #include <boost/random/uniform_int_distribution.hpp>
  21
  22 #include <boost/random/detail/disable_warnings.hpp>
  23
  24 namespace boost {
  25 namespace random {
  26
  27 /**
  28  * Instantiations of class template random_number_generator model a
  29  * RandomNumberGenerator (std:25.2.11 [lib.alg.random.shuffle]). On
  30  * each invocation, it returns a uniformly distributed integer in
  31  * the range [0..n).
  32  *
  33  * The template parameter IntType shall denote some integer-like value type.
  34  */
  35 template<class URNG, class IntType = long>
  36 class random_number_generator
  37 {
  38 public:
  39     typedef URNG base_type;
  40     typedef IntType argument_type;
  41     typedef IntType result_type;
  42     /**
  43      * Constructs a random_number_generator functor with the given
  44      * \uniform_random_number_generator as the underlying source of
  45      * random numbers.
  46      */
  47     random_number_generator(base_type& rng) : _rng(rng) {}
  48
  49     // compiler-generated copy ctor is fine
  50     // assignment is disallowed because there is a reference member
  51
  52     /**
  53      * Returns a value in the range [0, n)
  54      */
  55     result_type operator()(argument_type n)
  56     {
  57         BOOST_ASSERT(n > 0);
  58         return uniform_int_distribution<IntType>(0, n-1)(_rng);
  59     }
  60
  61 private:
  62     base_type& _rng;
  63 };
  64
  65 } // namespace random
  66
  67 using random::random_number_generator;
  68
  69 } // namespace boost
  70
  71 #include <boost/random/detail/enable_warnings.hpp>
  72
  73 #endif // BOOST_RANDOM_RANDOM_NUMBER_GENERATOR_HPP