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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H
#define _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H
#include <__algorithm/upper_bound.h>
#include <__config>
#include <__random/uniform_real_distribution.h>
#include <cstddef>
#include <iosfwd>
#include <numeric>
#include <vector>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
template<class _IntType = int>
class _LIBCPP_TEMPLATE_VIS discrete_distribution
{
public:
// types
typedef _IntType result_type;
class _LIBCPP_TEMPLATE_VIS param_type
{
vector<double> __p_;
public:
typedef discrete_distribution distribution_type;
_LIBCPP_INLINE_VISIBILITY
param_type() {}
template<class _InputIterator>
_LIBCPP_INLINE_VISIBILITY
param_type(_InputIterator __f, _InputIterator __l)
: __p_(__f, __l) {__init();}
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_INLINE_VISIBILITY
param_type(initializer_list<double> __wl)
: __p_(__wl.begin(), __wl.end()) {__init();}
#endif // _LIBCPP_CXX03_LANG
template<class _UnaryOperation>
param_type(size_t __nw, double __xmin, double __xmax,
_UnaryOperation __fw);
vector<double> probabilities() const;
friend _LIBCPP_INLINE_VISIBILITY
bool operator==(const param_type& __x, const param_type& __y)
{return __x.__p_ == __y.__p_;}
friend _LIBCPP_INLINE_VISIBILITY
bool operator!=(const param_type& __x, const param_type& __y)
{return !(__x == __y);}
private:
void __init();
friend class discrete_distribution;
template <class _CharT, class _Traits, class _IT>
friend
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os,
const discrete_distribution<_IT>& __x);
template <class _CharT, class _Traits, class _IT>
friend
basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is,
discrete_distribution<_IT>& __x);
};
private:
param_type __p_;
public:
// constructor and reset functions
_LIBCPP_INLINE_VISIBILITY
discrete_distribution() {}
template<class _InputIterator>
_LIBCPP_INLINE_VISIBILITY
discrete_distribution(_InputIterator __f, _InputIterator __l)
: __p_(__f, __l) {}
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_INLINE_VISIBILITY
discrete_distribution(initializer_list<double> __wl)
: __p_(__wl) {}
#endif // _LIBCPP_CXX03_LANG
template<class _UnaryOperation>
_LIBCPP_INLINE_VISIBILITY
discrete_distribution(size_t __nw, double __xmin, double __xmax,
_UnaryOperation __fw)
: __p_(__nw, __xmin, __xmax, __fw) {}
_LIBCPP_INLINE_VISIBILITY
explicit discrete_distribution(const param_type& __p)
: __p_(__p) {}
_LIBCPP_INLINE_VISIBILITY
void reset() {}
// generating functions
template<class _URNG>
_LIBCPP_INLINE_VISIBILITY
result_type operator()(_URNG& __g)
{return (*this)(__g, __p_);}
template<class _URNG> result_type operator()(_URNG& __g, const param_type& __p);
// property functions
_LIBCPP_INLINE_VISIBILITY
vector<double> probabilities() const {return __p_.probabilities();}
_LIBCPP_INLINE_VISIBILITY
param_type param() const {return __p_;}
_LIBCPP_INLINE_VISIBILITY
void param(const param_type& __p) {__p_ = __p;}
_LIBCPP_INLINE_VISIBILITY
result_type min() const {return 0;}
_LIBCPP_INLINE_VISIBILITY
result_type max() const {return __p_.__p_.size();}
friend _LIBCPP_INLINE_VISIBILITY
bool operator==(const discrete_distribution& __x,
const discrete_distribution& __y)
{return __x.__p_ == __y.__p_;}
friend _LIBCPP_INLINE_VISIBILITY
bool operator!=(const discrete_distribution& __x,
const discrete_distribution& __y)
{return !(__x == __y);}
template <class _CharT, class _Traits, class _IT>
friend
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os,
const discrete_distribution<_IT>& __x);
template <class _CharT, class _Traits, class _IT>
friend
basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is,
discrete_distribution<_IT>& __x);
};
template<class _IntType>
template<class _UnaryOperation>
discrete_distribution<_IntType>::param_type::param_type(size_t __nw,
double __xmin,
double __xmax,
_UnaryOperation __fw)
{
if (__nw > 1)
{
__p_.reserve(__nw - 1);
double __d = (__xmax - __xmin) / __nw;
double __d2 = __d / 2;
for (size_t __k = 0; __k < __nw; ++__k)
__p_.push_back(__fw(__xmin + __k * __d + __d2));
__init();
}
}
template<class _IntType>
void
discrete_distribution<_IntType>::param_type::__init()
{
if (!__p_.empty())
{
if (__p_.size() > 1)
{
double __s = _VSTD::accumulate(__p_.begin(), __p_.end(), 0.0);
for (vector<double>::iterator __i = __p_.begin(), __e = __p_.end(); __i < __e; ++__i)
*__i /= __s;
vector<double> __t(__p_.size() - 1);
_VSTD::partial_sum(__p_.begin(), __p_.end() - 1, __t.begin());
swap(__p_, __t);
}
else
{
__p_.clear();
__p_.shrink_to_fit();
}
}
}
template<class _IntType>
vector<double>
discrete_distribution<_IntType>::param_type::probabilities() const
{
size_t __n = __p_.size();
vector<double> __p(__n+1);
_VSTD::adjacent_difference(__p_.begin(), __p_.end(), __p.begin());
if (__n > 0)
__p[__n] = 1 - __p_[__n-1];
else
__p[0] = 1;
return __p;
}
template<class _IntType>
template<class _URNG>
_IntType
discrete_distribution<_IntType>::operator()(_URNG& __g, const param_type& __p)
{
uniform_real_distribution<double> __gen;
return static_cast<_IntType>(
_VSTD::upper_bound(__p.__p_.begin(), __p.__p_.end(), __gen(__g)) -
__p.__p_.begin());
}
template <class _CharT, class _Traits, class _IT>
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os,
const discrete_distribution<_IT>& __x)
{
__save_flags<_CharT, _Traits> __lx(__os);
typedef basic_ostream<_CharT, _Traits> _OStream;
__os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
_OStream::scientific);
_CharT __sp = __os.widen(' ');
__os.fill(__sp);
size_t __n = __x.__p_.__p_.size();
__os << __n;
for (size_t __i = 0; __i < __n; ++__i)
__os << __sp << __x.__p_.__p_[__i];
return __os;
}
template <class _CharT, class _Traits, class _IT>
basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is,
discrete_distribution<_IT>& __x)
{
__save_flags<_CharT, _Traits> __lx(__is);
typedef basic_istream<_CharT, _Traits> _Istream;
__is.flags(_Istream::dec | _Istream::skipws);
size_t __n;
__is >> __n;
vector<double> __p(__n);
for (size_t __i = 0; __i < __n; ++__i)
__is >> __p[__i];
if (!__is.fail())
swap(__x.__p_.__p_, __p);
return __is;
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANDOM_DISCRETE_DISTRIBUTION_H
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