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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_DISCARD_BLOCK_ENGINE_H
#define _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H
#include <__config>
#include <__random/is_seed_sequence.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_convertible.h>
#include <__utility/move.h>
#include <cstddef>
#include <iosfwd>
#include <limits>
#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 _Engine, size_t __p, size_t __r>
class _LIBCPP_TEMPLATE_VIS discard_block_engine {
_Engine __e_;
int __n_;
static_assert(0 < __r, "discard_block_engine invalid parameters");
static_assert(__r <= __p, "discard_block_engine invalid parameters");
#ifndef _LIBCPP_CXX03_LANG // numeric_limits::max() is not constexpr in C++03
static_assert(__r <= numeric_limits<int>::max(), "discard_block_engine invalid parameters");
#endif
public:
// types
typedef typename _Engine::result_type result_type;
// engine characteristics
static _LIBCPP_CONSTEXPR const size_t block_size = __p;
static _LIBCPP_CONSTEXPR const size_t used_block = __r;
#ifdef _LIBCPP_CXX03_LANG
static const result_type _Min = _Engine::_Min;
static const result_type _Max = _Engine::_Max;
#else
static constexpr result_type _Min = _Engine::min();
static constexpr result_type _Max = _Engine::max();
#endif
_LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type min() { return _Engine::min(); }
_LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR result_type max() { return _Engine::max(); }
// constructors and seeding functions
_LIBCPP_HIDE_FROM_ABI discard_block_engine() : __n_(0) {}
_LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(const _Engine& __e) : __e_(__e), __n_(0) {}
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(_Engine&& __e) : __e_(std::move(__e)), __n_(0) {}
#endif // _LIBCPP_CXX03_LANG
_LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(result_type __sd) : __e_(__sd), __n_(0) {}
template <
class _Sseq,
__enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value && !is_convertible<_Sseq, _Engine>::value,
int> = 0>
_LIBCPP_HIDE_FROM_ABI explicit discard_block_engine(_Sseq& __q) : __e_(__q), __n_(0) {}
_LIBCPP_HIDE_FROM_ABI void seed() {
__e_.seed();
__n_ = 0;
}
_LIBCPP_HIDE_FROM_ABI void seed(result_type __sd) {
__e_.seed(__sd);
__n_ = 0;
}
template <class _Sseq, __enable_if_t<__is_seed_sequence<_Sseq, discard_block_engine>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI void seed(_Sseq& __q) {
__e_.seed(__q);
__n_ = 0;
}
// generating functions
_LIBCPP_HIDE_FROM_ABI result_type operator()();
_LIBCPP_HIDE_FROM_ABI void discard(unsigned long long __z) {
for (; __z; --__z)
operator()();
}
// property functions
_LIBCPP_HIDE_FROM_ABI const _Engine& base() const _NOEXCEPT { return __e_; }
template <class _Eng, size_t _Pp, size_t _Rp>
friend bool
operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y);
template <class _Eng, size_t _Pp, size_t _Rp>
friend bool
operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y);
template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
friend basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const discard_block_engine<_Eng, _Pp, _Rp>& __x);
template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
friend basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is, discard_block_engine<_Eng, _Pp, _Rp>& __x);
};
template <class _Engine, size_t __p, size_t __r>
_LIBCPP_CONSTEXPR const size_t discard_block_engine<_Engine, __p, __r>::block_size;
template <class _Engine, size_t __p, size_t __r>
_LIBCPP_CONSTEXPR const size_t discard_block_engine<_Engine, __p, __r>::used_block;
template <class _Engine, size_t __p, size_t __r>
typename discard_block_engine<_Engine, __p, __r>::result_type discard_block_engine<_Engine, __p, __r>::operator()() {
if (__n_ >= static_cast<int>(__r)) {
__e_.discard(__p - __r);
__n_ = 0;
}
++__n_;
return __e_();
}
template <class _Eng, size_t _Pp, size_t _Rp>
inline _LIBCPP_HIDE_FROM_ABI bool
operator==(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y) {
return __x.__n_ == __y.__n_ && __x.__e_ == __y.__e_;
}
template <class _Eng, size_t _Pp, size_t _Rp>
inline _LIBCPP_HIDE_FROM_ABI bool
operator!=(const discard_block_engine<_Eng, _Pp, _Rp>& __x, const discard_block_engine<_Eng, _Pp, _Rp>& __y) {
return !(__x == __y);
}
template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const discard_block_engine<_Eng, _Pp, _Rp>& __x) {
__save_flags<_CharT, _Traits> __lx(__os);
typedef basic_ostream<_CharT, _Traits> _Ostream;
__os.flags(_Ostream::dec | _Ostream::left);
_CharT __sp = __os.widen(' ');
__os.fill(__sp);
return __os << __x.__e_ << __sp << __x.__n_;
}
template <class _CharT, class _Traits, class _Eng, size_t _Pp, size_t _Rp>
_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is, discard_block_engine<_Eng, _Pp, _Rp>& __x) {
__save_flags<_CharT, _Traits> __lx(__is);
typedef basic_istream<_CharT, _Traits> _Istream;
__is.flags(_Istream::dec | _Istream::skipws);
_Eng __e;
int __n;
__is >> __e >> __n;
if (!__is.fail()) {
__x.__e_ = __e;
__x.__n_ = __n;
}
return __is;
}
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANDOM_DISCARD_BLOCK_ENGINE_H
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