libcxx/include/__random/bernoulli_distribution.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___RANDOM_BERNOULLI_DISTRIBUTION_H
  10 #define _LIBCPP___RANDOM_BERNOULLI_DISTRIBUTION_H
  11
  12 #include <__config>
  13 #include <__random/is_valid.h>
  14 #include <__random/uniform_real_distribution.h>
  15 #include <iosfwd>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #  pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_PUSH_MACROS
  22 #include <__undef_macros>
  23
  24 _LIBCPP_BEGIN_NAMESPACE_STD
  25
  26 class _LIBCPP_TEMPLATE_VIS bernoulli_distribution
  27 {
  28 public:
  29     // types
  30     typedef bool result_type;
  31
  32     class _LIBCPP_TEMPLATE_VIS param_type
  33     {
  34         double __p_;
  35     public:
  36         typedef bernoulli_distribution distribution_type;
  37
  38         _LIBCPP_INLINE_VISIBILITY
  39         explicit param_type(double __p = 0.5) : __p_(__p) {}
  40
  41         _LIBCPP_INLINE_VISIBILITY
  42         double p() const {return __p_;}
  43
  44         friend _LIBCPP_INLINE_VISIBILITY
  45             bool operator==(const param_type& __x, const param_type& __y)
  46             {return __x.__p_ == __y.__p_;}
  47         friend _LIBCPP_INLINE_VISIBILITY
  48             bool operator!=(const param_type& __x, const param_type& __y)
  49             {return !(__x == __y);}
  50     };
  51
  52 private:
  53     param_type __p_;
  54
  55 public:
  56     // constructors and reset functions
  57 #ifndef _LIBCPP_CXX03_LANG
  58     _LIBCPP_INLINE_VISIBILITY
  59     bernoulli_distribution() : bernoulli_distribution(0.5) {}
  60     _LIBCPP_INLINE_VISIBILITY
  61     explicit bernoulli_distribution(double __p) : __p_(param_type(__p)) {}
  62 #else
  63     _LIBCPP_INLINE_VISIBILITY
  64     explicit bernoulli_distribution(double __p = 0.5) : __p_(param_type(__p)) {}
  65 #endif
  66     _LIBCPP_INLINE_VISIBILITY
  67     explicit bernoulli_distribution(const param_type& __p) : __p_(__p) {}
  68     _LIBCPP_INLINE_VISIBILITY
  69     void reset() {}
  70
  71     // generating functions
  72     template<class _URNG>
  73         _LIBCPP_INLINE_VISIBILITY
  74         result_type operator()(_URNG& __g)
  75         {return (*this)(__g, __p_);}
  76     template<class _URNG> _LIBCPP_INLINE_VISIBILITY result_type operator()(_URNG& __g, const param_type& __p);
  77
  78     // property functions
  79     _LIBCPP_INLINE_VISIBILITY
  80     double p() const {return __p_.p();}
  81
  82     _LIBCPP_INLINE_VISIBILITY
  83     param_type param() const {return __p_;}
  84     _LIBCPP_INLINE_VISIBILITY
  85     void param(const param_type& __p) {__p_ = __p;}
  86
  87     _LIBCPP_INLINE_VISIBILITY
  88     result_type min() const {return false;}
  89     _LIBCPP_INLINE_VISIBILITY
  90     result_type max() const {return true;}
  91
  92     friend _LIBCPP_INLINE_VISIBILITY
  93         bool operator==(const bernoulli_distribution& __x,
  94                         const bernoulli_distribution& __y)
  95         {return __x.__p_ == __y.__p_;}
  96     friend _LIBCPP_INLINE_VISIBILITY
  97         bool operator!=(const bernoulli_distribution& __x,
  98                         const bernoulli_distribution& __y)
  99         {return !(__x == __y);}
 100 };
 101
 102 template<class _URNG>
 103 inline
 104 bernoulli_distribution::result_type
 105 bernoulli_distribution::operator()(_URNG& __g, const param_type& __p)
 106 {
 107     static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
 108     uniform_real_distribution<double> __gen;
 109     return __gen(__g) < __p.p();
 110 }
 111
 112 template <class _CharT, class _Traits>
 113 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 114 operator<<(basic_ostream<_CharT, _Traits>& __os, const bernoulli_distribution& __x)
 115 {
 116     __save_flags<_CharT, _Traits> __lx(__os);
 117     typedef basic_ostream<_CharT, _Traits> _OStream;
 118     __os.flags(_OStream::dec | _OStream::left | _OStream::fixed |
 119                _OStream::scientific);
 120     _CharT __sp = __os.widen(' ');
 121     __os.fill(__sp);
 122     return __os << __x.p();
 123 }
 124
 125 template <class _CharT, class _Traits>
 126 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 127 operator>>(basic_istream<_CharT, _Traits>& __is, bernoulli_distribution& __x)
 128 {
 129     typedef bernoulli_distribution _Eng;
 130     typedef typename _Eng::param_type param_type;
 131     __save_flags<_CharT, _Traits> __lx(__is);
 132     typedef basic_istream<_CharT, _Traits> _Istream;
 133     __is.flags(_Istream::dec | _Istream::skipws);
 134     double __p;
 135     __is >> __p;
 136     if (!__is.fail())
 137         __x.param(param_type(__p));
 138     return __is;
 139 }
 140
 141 _LIBCPP_END_NAMESPACE_STD
 142
 143 _LIBCPP_POP_MACROS
 144
 145 #endif // _LIBCPP___RANDOM_BERNOULLI_DISTRIBUTION_H