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265 lines
8.7 KiB
C++
265 lines
8.7 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___RANDOM_UNIFORM_INT_DISTRIBUTION_H
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#define _LIBCPP___RANDOM_UNIFORM_INT_DISTRIBUTION_H
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#include <__bit/countl.h>
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#include <__config>
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#include <__cstddef/size_t.h>
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#include <__random/is_valid.h>
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#include <__random/log2.h>
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#include <__type_traits/conditional.h>
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#include <__type_traits/make_unsigned.h>
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#include <cstdint>
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#include <iosfwd>
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#include <limits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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template <class _Engine, class _UIntType>
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class __independent_bits_engine {
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public:
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// types
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typedef _UIntType result_type;
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private:
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typedef typename _Engine::result_type _Engine_result_type;
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typedef __conditional_t<sizeof(_Engine_result_type) <= sizeof(result_type), result_type, _Engine_result_type>
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_Working_result_type;
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_Engine& __e_;
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size_t __w_;
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size_t __w0_;
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size_t __n_;
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size_t __n0_;
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_Working_result_type __y0_;
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_Working_result_type __y1_;
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_Engine_result_type __mask0_;
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_Engine_result_type __mask1_;
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#ifdef _LIBCPP_CXX03_LANG
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static const _Working_result_type _Rp = _Engine::_Max - _Engine::_Min + _Working_result_type(1);
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#else
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static _LIBCPP_CONSTEXPR const _Working_result_type _Rp = _Engine::max() - _Engine::min() + _Working_result_type(1);
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#endif
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static _LIBCPP_CONSTEXPR const size_t __m = __log2<_Working_result_type, _Rp>::value;
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static _LIBCPP_CONSTEXPR const size_t _WDt = numeric_limits<_Working_result_type>::digits;
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static _LIBCPP_CONSTEXPR const size_t _EDt = numeric_limits<_Engine_result_type>::digits;
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public:
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// constructors and seeding functions
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_LIBCPP_HIDE_FROM_ABI __independent_bits_engine(_Engine& __e, size_t __w);
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// generating functions
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_LIBCPP_HIDE_FROM_ABI result_type operator()() { return __eval(integral_constant<bool, _Rp != 0>()); }
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private:
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_LIBCPP_HIDE_FROM_ABI result_type __eval(false_type);
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_LIBCPP_HIDE_FROM_ABI result_type __eval(true_type);
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};
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template <class _Engine, class _UIntType>
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__independent_bits_engine<_Engine, _UIntType>::__independent_bits_engine(_Engine& __e, size_t __w)
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: __e_(__e), __w_(__w) {
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__n_ = __w_ / __m + (__w_ % __m != 0);
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__w0_ = __w_ / __n_;
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if (_Rp == 0)
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__y0_ = _Rp;
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else if (__w0_ < _WDt)
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__y0_ = (_Rp >> __w0_) << __w0_;
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else
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__y0_ = 0;
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if (_Rp - __y0_ > __y0_ / __n_) {
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++__n_;
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__w0_ = __w_ / __n_;
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if (__w0_ < _WDt)
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__y0_ = (_Rp >> __w0_) << __w0_;
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else
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__y0_ = 0;
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}
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__n0_ = __n_ - __w_ % __n_;
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if (__w0_ < _WDt - 1)
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__y1_ = (_Rp >> (__w0_ + 1)) << (__w0_ + 1);
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else
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__y1_ = 0;
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__mask0_ = __w0_ > 0 ? _Engine_result_type(~0) >> (_EDt - __w0_) : _Engine_result_type(0);
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__mask1_ = __w0_ < _EDt - 1 ? _Engine_result_type(~0) >> (_EDt - (__w0_ + 1)) : _Engine_result_type(~0);
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}
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template <class _Engine, class _UIntType>
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inline _UIntType __independent_bits_engine<_Engine, _UIntType>::__eval(false_type) {
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return static_cast<result_type>(__e_() & __mask0_);
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}
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template <class _Engine, class _UIntType>
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_UIntType __independent_bits_engine<_Engine, _UIntType>::__eval(true_type) {
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const size_t __w_rt = numeric_limits<result_type>::digits;
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result_type __sp = 0;
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for (size_t __k = 0; __k < __n0_; ++__k) {
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_Engine_result_type __u;
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do {
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__u = __e_() - _Engine::min();
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} while (__u >= __y0_);
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if (__w0_ < __w_rt)
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__sp <<= __w0_;
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else
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__sp = 0;
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__sp += __u & __mask0_;
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}
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for (size_t __k = __n0_; __k < __n_; ++__k) {
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_Engine_result_type __u;
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do {
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__u = __e_() - _Engine::min();
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} while (__u >= __y1_);
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if (__w0_ < __w_rt - 1)
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__sp <<= __w0_ + 1;
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else
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__sp = 0;
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__sp += __u & __mask1_;
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}
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return __sp;
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}
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template <class _IntType = int>
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class uniform_int_distribution {
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static_assert(__libcpp_random_is_valid_inttype<_IntType>::value, "IntType must be a supported integer type");
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public:
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// types
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typedef _IntType result_type;
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class param_type {
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result_type __a_;
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result_type __b_;
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public:
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typedef uniform_int_distribution distribution_type;
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_LIBCPP_HIDE_FROM_ABI explicit param_type(result_type __a = 0, result_type __b = numeric_limits<result_type>::max())
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: __a_(__a), __b_(__b) {}
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_LIBCPP_HIDE_FROM_ABI result_type a() const { return __a_; }
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_LIBCPP_HIDE_FROM_ABI result_type b() const { return __b_; }
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_LIBCPP_HIDE_FROM_ABI friend bool operator==(const param_type& __x, const param_type& __y) {
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return __x.__a_ == __y.__a_ && __x.__b_ == __y.__b_;
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}
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_LIBCPP_HIDE_FROM_ABI friend bool operator!=(const param_type& __x, const param_type& __y) { return !(__x == __y); }
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};
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private:
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param_type __p_;
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public:
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// constructors and reset functions
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#ifndef _LIBCPP_CXX03_LANG
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_LIBCPP_HIDE_FROM_ABI uniform_int_distribution() : uniform_int_distribution(0) {}
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_LIBCPP_HIDE_FROM_ABI explicit uniform_int_distribution(
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result_type __a, result_type __b = numeric_limits<result_type>::max())
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: __p_(param_type(__a, __b)) {}
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#else
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explicit uniform_int_distribution(result_type __a = 0, result_type __b = numeric_limits<result_type>::max())
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: __p_(param_type(__a, __b)) {}
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#endif
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_LIBCPP_HIDE_FROM_ABI explicit uniform_int_distribution(const param_type& __p) : __p_(__p) {}
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_LIBCPP_HIDE_FROM_ABI void reset() {}
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// generating functions
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template <class _URNG>
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_LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g) {
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return (*this)(__g, __p_);
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}
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template <class _URNG>
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_LIBCPP_HIDE_FROM_ABI result_type operator()(_URNG& __g, const param_type& __p);
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// property functions
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_LIBCPP_HIDE_FROM_ABI result_type a() const { return __p_.a(); }
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_LIBCPP_HIDE_FROM_ABI result_type b() const { return __p_.b(); }
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_LIBCPP_HIDE_FROM_ABI param_type param() const { return __p_; }
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_LIBCPP_HIDE_FROM_ABI void param(const param_type& __p) { __p_ = __p; }
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_LIBCPP_HIDE_FROM_ABI result_type min() const { return a(); }
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_LIBCPP_HIDE_FROM_ABI result_type max() const { return b(); }
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_LIBCPP_HIDE_FROM_ABI friend bool
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operator==(const uniform_int_distribution& __x, const uniform_int_distribution& __y) {
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return __x.__p_ == __y.__p_;
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}
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_LIBCPP_HIDE_FROM_ABI friend bool
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operator!=(const uniform_int_distribution& __x, const uniform_int_distribution& __y) {
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return !(__x == __y);
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}
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};
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template <class _IntType>
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template <class _URNG>
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typename uniform_int_distribution<_IntType>::result_type uniform_int_distribution<_IntType>::operator()(
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_URNG& __g, const param_type& __p) _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK {
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static_assert(__libcpp_random_is_valid_urng<_URNG>::value, "");
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typedef __conditional_t<sizeof(result_type) <= sizeof(uint32_t), uint32_t, __make_unsigned_t<result_type> > _UIntType;
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const _UIntType __rp = _UIntType(__p.b()) - _UIntType(__p.a()) + _UIntType(1);
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if (__rp == 1)
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return __p.a();
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const size_t __dt = numeric_limits<_UIntType>::digits;
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typedef __independent_bits_engine<_URNG, _UIntType> _Eng;
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if (__rp == 0)
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return static_cast<result_type>(_Eng(__g, __dt)());
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size_t __w = __dt - std::__countl_zero(__rp) - 1;
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if ((__rp & (numeric_limits<_UIntType>::max() >> (__dt - __w))) != 0)
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++__w;
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_Eng __e(__g, __w);
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_UIntType __u;
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do {
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__u = __e();
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} while (__u >= __rp);
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return static_cast<result_type>(__u + __p.a());
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}
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template <class _CharT, class _Traits, class _IT>
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_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
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operator<<(basic_ostream<_CharT, _Traits>& __os, const uniform_int_distribution<_IT>& __x) {
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__save_flags<_CharT, _Traits> __lx(__os);
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typedef basic_ostream<_CharT, _Traits> _Ostream;
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__os.flags(_Ostream::dec | _Ostream::left);
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_CharT __sp = __os.widen(' ');
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__os.fill(__sp);
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return __os << __x.a() << __sp << __x.b();
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}
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template <class _CharT, class _Traits, class _IT>
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_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
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operator>>(basic_istream<_CharT, _Traits>& __is, uniform_int_distribution<_IT>& __x) {
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typedef uniform_int_distribution<_IT> _Eng;
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typedef typename _Eng::result_type result_type;
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typedef typename _Eng::param_type param_type;
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__save_flags<_CharT, _Traits> __lx(__is);
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typedef basic_istream<_CharT, _Traits> _Istream;
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__is.flags(_Istream::dec | _Istream::skipws);
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result_type __a;
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result_type __b;
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__is >> __a >> __b;
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if (!__is.fail())
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__x.param(param_type(__a, __b));
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return __is;
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}
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___RANDOM_UNIFORM_INT_DISTRIBUTION_H
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