Chris@16: /* boost random/shuffle_order.hpp header file
Chris@16:  *
Chris@16:  * Copyright Jens Maurer 2000-2001
Chris@16:  * Copyright Steven Watanabe 2010
Chris@16:  * Distributed under the Boost Software License, Version 1.0. (See
Chris@16:  * accompanying file LICENSE_1_0.txt or copy at
Chris@16:  * http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  *
Chris@16:  * See http://www.boost.org for most recent version including documentation.
Chris@16:  *
Chris@101:  * $Id$
Chris@16:  *
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_RANDOM_SHUFFLE_ORDER_HPP
Chris@16: #define BOOST_RANDOM_SHUFFLE_ORDER_HPP
Chris@16: 
Chris@16: #include <iostream>
Chris@16: #include <algorithm>     // std::copy
Chris@16: #include <cassert>
Chris@16: #include <boost/config.hpp>
Chris@16: #include <boost/limits.hpp>
Chris@16: #include <boost/static_assert.hpp>
Chris@16: #include <boost/cstdint.hpp>
Chris@16: #include <boost/random/detail/operators.hpp>
Chris@16: #include <boost/random/detail/seed.hpp>
Chris@16: #include <boost/random/detail/signed_unsigned_tools.hpp>
Chris@16: #include <boost/random/linear_congruential.hpp>
Chris@16: 
Chris@16: #include <boost/random/detail/disable_warnings.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace random {
Chris@16: 
Chris@16: /**
Chris@16:  * Instatiations of class template @c shuffle_order_engine model a
Chris@16:  * \pseudo_random_number_generator. It mixes the output
Chris@16:  * of some (usually \linear_congruential_engine)
Chris@16:  * \uniform_random_number_generator to get better statistical properties.
Chris@16:  * The algorithm is described in
Chris@16:  *
Chris@16:  *  @blockquote
Chris@16:  *  "Improving a poor random number generator", Carter Bays
Chris@16:  *  and S.D. Durham, ACM Transactions on Mathematical Software,
Chris@16:  *  Vol 2, No. 1, March 1976, pp. 59-64.
Chris@16:  *  http://doi.acm.org/10.1145/355666.355670
Chris@16:  *  @endblockquote
Chris@16:  *
Chris@16:  * The output of the base generator is buffered in an array of
Chris@16:  * length k. Every output X(n) has a second role: It gives an
Chris@16:  * index into the array where X(n+1) will be retrieved. Used
Chris@16:  * array elements are replaced with fresh output from the base
Chris@16:  * generator.
Chris@16:  *
Chris@16:  * Template parameters are the base generator and the array
Chris@16:  * length k, which should be around 100.
Chris@16:  */
Chris@16: template<class UniformRandomNumberGenerator, std::size_t k>
Chris@16: class shuffle_order_engine
Chris@16: {
Chris@16: public:
Chris@16:     typedef UniformRandomNumberGenerator base_type;
Chris@16:     typedef typename base_type::result_type result_type;
Chris@16: 
Chris@16:     BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
Chris@16:     BOOST_STATIC_CONSTANT(std::size_t, buffer_size = k);
Chris@16:     BOOST_STATIC_CONSTANT(std::size_t, table_size = k);
Chris@16: 
Chris@16:     BOOST_STATIC_ASSERT(std::numeric_limits<result_type>::is_integer);
Chris@16:     BOOST_STATIC_ASSERT(k > 0);
Chris@16: 
Chris@16:     /**
Chris@16:      * Constructs a @c shuffle_order_engine by invoking the
Chris@16:      * default constructor of the base generator.
Chris@16:      *
Chris@16:      * Complexity: Exactly k+1 invocations of the base generator.
Chris@16:      */
Chris@16:     shuffle_order_engine() : _rng() { init(); }
Chris@16:     /**
Chris@16:      * Constructs a @c shuffle_output_engine by invoking the one-argument
Chris@16:      * constructor of the base generator with the parameter seed.
Chris@16:      *
Chris@16:      * Complexity: Exactly k+1 invocations of the base generator.
Chris@16:      */
Chris@16:     BOOST_RANDOM_DETAIL_ARITHMETIC_CONSTRUCTOR(shuffle_order_engine,
Chris@16:                                                result_type, s)
Chris@16:     { _rng.seed(s); init(); }
Chris@16:     BOOST_RANDOM_DETAIL_SEED_SEQ_CONSTRUCTOR(shuffle_order_engine, SeedSeq, seq)
Chris@16:     { _rng.seed(seq); init(); }
Chris@16:     /**
Chris@16:      * Constructs a @c shuffle_output_engine by using a copy
Chris@16:      * of the provided generator.
Chris@16:      *
Chris@16:      * Precondition: The template argument UniformRandomNumberGenerator
Chris@16:      * shall denote a CopyConstructible type.
Chris@16:      *
Chris@16:      * Complexity: Exactly k+1 invocations of the base generator.
Chris@16:      */
Chris@16:     explicit shuffle_order_engine(const base_type & rng) : _rng(rng) { init(); }
Chris@16: 
Chris@101: #ifndef BOOST_NO_CXX11_RVALUE_REFERENCES
Chris@16:     explicit shuffle_order_engine(base_type&& rng) : _rng(rng) { init(); }
Chris@16: #endif
Chris@16: 
Chris@16:     template<class It> shuffle_order_engine(It& first, It last)
Chris@16:       : _rng(first, last) { init(); }
Chris@16:     void seed() { _rng.seed(); init(); }
Chris@16:     /**
Chris@16:      * Invokes the one-argument seed method of the base generator
Chris@16:      * with the parameter seed and re-initializes the internal buffer array.
Chris@16:      *
Chris@16:      * Complexity: Exactly k+1 invocations of the base generator.
Chris@16:      */
Chris@16:     BOOST_RANDOM_DETAIL_ARITHMETIC_SEED(shuffle_order_engine,
Chris@16:         result_type, seed_arg)
Chris@16:     { _rng.seed(seed_arg); init(); }
Chris@16:     /**
Chris@16:      * Invokes the one-argument seed method of the base generator
Chris@16:      * with the parameter seq and re-initializes the internal buffer array.
Chris@16:      *
Chris@16:      * Complexity: Exactly k+1 invocations of the base generator.
Chris@16:      */
Chris@16:     BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(shuffle_order_engine, SeedSeq, seq)
Chris@16:     { _rng.seed(seq); init(); }
Chris@16:     template<class It> void seed(It& first, It last)
Chris@16:     { _rng.seed(first, last); init(); }
Chris@16: 
Chris@16:     const base_type& base() const { return _rng; }
Chris@16: 
Chris@16:     result_type operator()() {
Chris@16:         // calculating the range every time may seem wasteful.  However, this
Chris@16:         // makes the information locally available for the optimizer.
Chris@16:         typedef typename make_unsigned<result_type>::type base_unsigned;
Chris@16:         const base_unsigned brange =
Chris@16:             detail::subtract<result_type>()((max)(), (min)());
Chris@16:         const base_unsigned off =
Chris@16:             detail::subtract<result_type>()(y, (min)());
Chris@16: 
Chris@16:         base_unsigned j;
Chris@16:         if(k == 1) {
Chris@16:             j = 0;
Chris@16:         } else if(brange < (std::numeric_limits<base_unsigned>::max)() / k) {
Chris@16:             // try to do it in the native type if we know that it won't
Chris@16:             // overflow
Chris@16:             j = k * off / (brange + 1);
Chris@16:         } else if(brange < (std::numeric_limits<uintmax_t>::max)() / k) {
Chris@16:             // Otherwise try to use uint64_t
Chris@16:             j = static_cast<base_unsigned>(
Chris@16:                 static_cast<uintmax_t>(off) * k /
Chris@16:                 (static_cast<uintmax_t>(brange) + 1));
Chris@16:         } else {
Chris@16:             boost::uintmax_t divisor =
Chris@16:                 static_cast<boost::uintmax_t>(brange) + 1;
Chris@16:             j = static_cast<base_unsigned>(detail::muldiv(off, k, divisor));
Chris@16:         }
Chris@16:         // assert(0 <= j && j < k);
Chris@16:         y = v[j];
Chris@16:         v[j] = _rng();
Chris@16:         return y;
Chris@16:     }
Chris@16: 
Chris@16:     /** Advances the generator by z steps. */
Chris@16:     void discard(boost::uintmax_t z)
Chris@16:     {
Chris@16:         for(boost::uintmax_t j = 0; j < z; ++j) {
Chris@16:             (*this)();
Chris@16:         }
Chris@16:     }
Chris@16: 
Chris@16:     /** Fills a range with pseudo-random values. */
Chris@16:     template<class Iter>
Chris@16:     void generate(Iter first, Iter last)
Chris@16:     { detail::generate_from_int(*this, first, last); }
Chris@16: 
Chris@16:     /** Returns the smallest value that the generator can produce. */
Chris@16:     static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION ()
Chris@16:     { return (base_type::min)(); }
Chris@16:     /** Returns the largest value that the generator can produce. */
Chris@16:     static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION ()
Chris@16:     { return (base_type::max)(); }
Chris@16: 
Chris@16:     /** Writes a @c shuffle_order_engine to a @c std::ostream. */
Chris@16:     BOOST_RANDOM_DETAIL_OSTREAM_OPERATOR(os, shuffle_order_engine, s)
Chris@16:     {
Chris@16:         os << s._rng;
Chris@16:         for(std::size_t i = 0; i < k; ++i)
Chris@16:             os << ' ' << s.v[i];
Chris@16:         os << ' ' << s.y;
Chris@16:         return os;
Chris@16:     }
Chris@16: 
Chris@16:     /** Reads a @c shuffle_order_engine from a @c std::istream. */
Chris@16:     BOOST_RANDOM_DETAIL_ISTREAM_OPERATOR(is, shuffle_order_engine, s)
Chris@16:     {
Chris@16:         is >> s._rng;
Chris@16:         for(std::size_t i = 0; i < k; ++i)
Chris@16:             is >> std::ws >> s.v[i];
Chris@16:         is >> std::ws >> s.y;
Chris@16:         return is;
Chris@16:     }
Chris@16: 
Chris@16:     /** Returns true if the two generators will produce identical sequences. */
Chris@16:     BOOST_RANDOM_DETAIL_EQUALITY_OPERATOR(shuffle_order_engine, x, y)
Chris@16:     { return x._rng == y._rng && x.y == y.y && std::equal(x.v, x.v+k, y.v); }
Chris@16:     /** Returns true if the two generators will produce different sequences. */
Chris@16:     BOOST_RANDOM_DETAIL_INEQUALITY_OPERATOR(shuffle_order_engine)
Chris@16: 
Chris@16: private:
Chris@16: 
Chris@16:     /// \cond show_private
Chris@16: 
Chris@16:     void init()
Chris@16:     {
Chris@16:         // we cannot use std::generate, because it uses pass-by-value for _rng
Chris@16:         for(result_type * p = v; p != v+k; ++p)
Chris@16:             *p = _rng();
Chris@16:         y = _rng();
Chris@16:     }
Chris@16: 
Chris@16:     /// \endcond
Chris@16: 
Chris@16:     base_type _rng;
Chris@16:     result_type v[k];
Chris@16:     result_type y;
Chris@16: };
Chris@16: 
Chris@16: #ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
Chris@16: //  A definition is required even for integral static constants
Chris@16: template<class URNG, std::size_t k>
Chris@16: const bool shuffle_order_engine<URNG, k>::has_fixed_range;
Chris@16: template<class URNG, std::size_t k>
Chris@16: const std::size_t shuffle_order_engine<URNG, k>::table_size;
Chris@16: template<class URNG, std::size_t k>
Chris@16: const std::size_t shuffle_order_engine<URNG, k>::buffer_size;
Chris@16: #endif
Chris@16: 
Chris@16: /**
Chris@16:  * According to Harry Erwin (private e-mail), the specialization
Chris@16:  * @c kreutzer1986 was suggested in:
Chris@16:  *
Chris@16:  * @blockquote
Chris@16:  * "System Simulation: Programming Styles and Languages (International
Chris@16:  * Computer Science Series)", Wolfgang Kreutzer, Addison-Wesley, December 1986.
Chris@16:  * @endblockquote
Chris@16:  */
Chris@16: typedef shuffle_order_engine<
Chris@16:     linear_congruential_engine<uint32_t, 1366, 150889, 714025>,
Chris@16:     97> kreutzer1986;
Chris@16: 
Chris@16: /**
Chris@16:  * The specialization @c knuth_b is specified by the C++ standard.
Chris@16:  * It is described in
Chris@16:  *
Chris@16:  * @blockquote
Chris@16:  * "The Art of Computer Programming, Second Edition, Volume 2,
Chris@16:  * Seminumerical Algorithms", Donald Knuth, Addison-Wesley, 1981.
Chris@16:  * @endblockquote
Chris@16:  */
Chris@16: typedef shuffle_order_engine<minstd_rand0, 256> knuth_b;
Chris@16: 
Chris@16: } // namespace random
Chris@16: 
Chris@16: using random::kreutzer1986;
Chris@16: 
Chris@16: } // namespace boost
Chris@16: 
Chris@16: #include <boost/random/detail/enable_warnings.hpp>
Chris@16: 
Chris@16: #endif // BOOST_RANDOM_SHUFFLE_OUTPUT_HPP