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      */
random_number_generator(base_type & rng)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      */
operator ()(argument_type n)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
74