__cxx03/__random/bernoulli_distribution.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CXX03___RANDOM_BERNOULLI_DISTRIBUTION_H
0010 #define _LIBCPP___CXX03___RANDOM_BERNOULLI_DISTRIBUTION_H
0011
0012 #include <__cxx03/__config>
0013 #include <__cxx03/__random/is_valid.h>
0014 #include <__cxx03/__random/uniform_real_distribution.h>
0015 #include <__cxx03/iosfwd>
0016
0017 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0018 #  pragma GCC system_header
0019 #endif
0020
0021 _LIBCPP_PUSH_MACROS
0022 #include <__cxx03/__undef_macros>
0023
0024 _LIBCPP_BEGIN_NAMESPACE_STD
0025
0026 class _LIBCPP_TEMPLATE_VIS bernoulli_distribution {
0027 public:
0028   // types
0029   typedef bool result_type;
0030
0031   class _LIBCPP_TEMPLATE_VIS param_type {
0032     double __p_;
0033
0034   public:
0035     typedef bernoulli_distribution distribution_type;
0036
0037     _LIBCPP_HIDE_FROM_ABI explicit param_type(double __p = 0.5) : __p_(__p) {}
0038
0039     _LIBCPP_HIDE_FROM_ABI double p() const { return __p_; }
0040
0041     friend _LIBCPP_HIDE_FROM_ABI bool operator==(const param_type& __x, const param_type& __y) {
0042       return __x.__p_ == __y.__p_;
0043     }
0044     friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
0045   };
0046
0047 private:
0048   param_type __p_;
0049
0050 public:
0051   // constructors and reset functions
0052 #ifndef _LIBCPP_CXX03_LANG
0053   _LIBCPP_HIDE_FROM_ABI bernoulli_distribution() : bernoulli_distribution(0.5) {}
0054   _LIBCPP_HIDE_FROM_ABI explicit bernoulli_distribution(double __p) : __p_(param_type(__p)) {}
0055 #else
0056   _LIBCPP_HIDE_FROM_ABI explicit bernoulli_distribution(double __p = 0.5) : __p_(param_type(__p)) {}
0057 #endif
0058   _LIBCPP_HIDE_FROM_ABI explicit bernoulli_distribution(const param_type& __p) : __p_(__p) {}
0059   _LIBCPP_HIDE_FROM_ABI void reset() {}
0060
0061   // generating functions
0062   template <class _URNG>
0063   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
0064     return (*this)(__g, __p_);
0065   }
0066   template <class _URNG>
0067   _LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
0068
0069   // property functions
0070   _LIBCPP_HIDE_FROM_ABI double p() const { return __p_.p(); }
0071
0072   _LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
0073   _LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
0074
0075   _LIBCPP_HIDE_FROM_ABI result_type min() const { return false; }
0076   _LIBCPP_HIDE_FROM_ABI result_type max() const { return true; }
0077
0078   friend _LIBCPP_HIDE_FROM_ABI bool operator==(const bernoulli_distribution& __x, const bernoulli_distribution& __y) {
0079     return __x.__p_ == __y.__p_;
0080   }
0081   friend _LIBCPP_HIDE_FROM_ABI bool operator!=(const bernoulli_distribution& __x, const bernoulli_distribution& __y) {
0082     return !(__x == __y);
0083   }
0084 };
0085
0086 template <class _URNG>
0087 inline bernoulli_distribution::result_type bernoulli_distribution::operator()(_URNG& __g, const param_type& __p) {
0088   static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
0089   uniform_real_distribution<double> __gen;
0090   return __gen(__g) < __p.p();
0091 }
0092
0093 template <class _CharT, class _Traits>
0094 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
0095 operator<<(basic_ostream<_CharT, _Traits>& __os, const bernoulli_distribution& __x) {
0096   __save_flags<_CharT, _Traits> __lx(__os);
0097   typedef basic_ostream<_CharT, _Traits> _OStream;
0098   __os.flags(_OStream::dec | _OStream::left | _OStream::fixed | _OStream::scientific);
0099   _CharT __sp = __os.widen(' ');
0100   __os.fill(__sp);
0101   return __os << __x.p();
0102 }
0103
0104 template <class _CharT, class _Traits>
0105 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
0106 operator>>(basic_istream<_CharT, _Traits>& __is, bernoulli_distribution& __x) {
0107   typedef bernoulli_distribution _Eng;
0108   typedef typename _Eng::param_type param_type;
0109   __save_flags<_CharT, _Traits> __lx(__is);
0110   typedef basic_istream<_CharT, _Traits> _Istream;
0111   __is.flags(_Istream::dec | _Istream::skipws);
0112   double __p;
0113   __is >> __p;
0114   if (!__is.fail())
0115     __x.param(param_type(__p));
0116   return __is;
0117 }
0118
0119 _LIBCPP_END_NAMESPACE_STD
0120
0121 _LIBCPP_POP_MACROS
0122
0123 #endif // _LIBCPP___CXX03___RANDOM_BERNOULLI_DISTRIBUTION_H