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llvm-project/libcxx/include/__ranges/iota_view.h

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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// 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___RANGES_IOTA_VIEW_H
#define _LIBCPP___RANGES_IOTA_VIEW_H
#include <__assert>
#include <__compare/three_way_comparable.h>
#include <__concepts/arithmetic.h>
#include <__concepts/constructible.h>
#include <__concepts/convertible_to.h>
#include <__concepts/copyable.h>
#include <__concepts/equality_comparable.h>
#include <__concepts/invocable.h>
#include <__concepts/same_as.h>
#include <__concepts/semiregular.h>
#include <__concepts/totally_ordered.h>
#include <__config>
#include <__functional/ranges_operations.h>
#include <__iterator/concepts.h>
#include <__iterator/incrementable_traits.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/unreachable_sentinel.h>
#include <__ranges/copyable_box.h>
#include <__ranges/enable_borrowed_range.h>
#include <__ranges/view_interface.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
namespace ranges {
template<class _Int>
struct __get_wider_signed {
static auto __call() {
if constexpr (sizeof(_Int) < sizeof(short)) return type_identity<short>{};
else if constexpr (sizeof(_Int) < sizeof(int)) return type_identity<int>{};
else if constexpr (sizeof(_Int) < sizeof(long)) return type_identity<long>{};
else return type_identity<long long>{};
static_assert(sizeof(_Int) <= sizeof(long long),
"Found integer-like type that is bigger than largest integer like type.");
}
using type = typename decltype(__call())::type;
};
template<class _Start>
using _IotaDiffT = typename _If<
(!integral<_Start> || sizeof(iter_difference_t<_Start>) > sizeof(_Start)),
type_identity<iter_difference_t<_Start>>,
__get_wider_signed<_Start>
>::type;
template<class _Iter>
concept __decrementable = incrementable<_Iter> && requires(_Iter __i) {
{ --__i } -> same_as<_Iter&>;
{ __i-- } -> same_as<_Iter>;
};
template<class _Iter>
concept __advanceable =
__decrementable<_Iter> && totally_ordered<_Iter> &&
requires(_Iter __i, const _Iter __j, const _IotaDiffT<_Iter> __n) {
{ __i += __n } -> same_as<_Iter&>;
{ __i -= __n } -> same_as<_Iter&>;
_Iter(__j + __n);
_Iter(__n + __j);
_Iter(__j - __n);
{ __j - __j } -> convertible_to<_IotaDiffT<_Iter>>;
};
template<class>
struct __iota_iterator_category {};
template<incrementable _Tp>
struct __iota_iterator_category<_Tp> {
using iterator_category = input_iterator_tag;
};
template <weakly_incrementable _Start, semiregular _BoundSentinel = unreachable_sentinel_t>
requires __weakly_equality_comparable_with<_Start, _BoundSentinel> && copyable<_Start>
class iota_view : public view_interface<iota_view<_Start, _BoundSentinel>> {
struct __iterator : public __iota_iterator_category<_Start> {
friend class iota_view;
using iterator_concept =
_If<__advanceable<_Start>, random_access_iterator_tag,
_If<__decrementable<_Start>, bidirectional_iterator_tag,
_If<incrementable<_Start>, forward_iterator_tag,
/*Else*/ input_iterator_tag>>>;
using value_type = _Start;
using difference_type = _IotaDiffT<_Start>;
_Start __value_ = _Start();
_LIBCPP_HIDE_FROM_ABI
__iterator() requires default_initializable<_Start> = default;
_LIBCPP_HIDE_FROM_ABI
constexpr explicit __iterator(_Start __value) : __value_(std::move(__value)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr _Start operator*() const noexcept(is_nothrow_copy_constructible_v<_Start>) {
return __value_;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator++() {
++__value_;
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr void operator++(int) { ++*this; }
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator operator++(int) requires incrementable<_Start> {
auto __tmp = *this;
++*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator--() requires __decrementable<_Start> {
--__value_;
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator operator--(int) requires __decrementable<_Start> {
auto __tmp = *this;
--*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator+=(difference_type __n)
requires __advanceable<_Start>
{
if constexpr (__integer_like<_Start> && !__signed_integer_like<_Start>) {
if (__n >= difference_type(0)) {
__value_ += static_cast<_Start>(__n);
} else {
__value_ -= static_cast<_Start>(-__n);
}
} else {
__value_ += __n;
}
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator-=(difference_type __n)
requires __advanceable<_Start>
{
if constexpr (__integer_like<_Start> && !__signed_integer_like<_Start>) {
if (__n >= difference_type(0)) {
__value_ -= static_cast<_Start>(__n);
} else {
__value_ += static_cast<_Start>(-__n);
}
} else {
__value_ -= __n;
}
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr _Start operator[](difference_type __n) const
requires __advanceable<_Start>
{
return _Start(__value_ + __n);
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
requires equality_comparable<_Start>
{
return __x.__value_ == __y.__value_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
requires totally_ordered<_Start>
{
return __x.__value_ < __y.__value_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
requires totally_ordered<_Start>
{
return __y < __x;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
requires totally_ordered<_Start>
{
return !(__y < __x);
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
requires totally_ordered<_Start>
{
return !(__x < __y);
}
friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
requires totally_ordered<_Start> && three_way_comparable<_Start>
{
return __x.__value_ <=> __y.__value_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr __iterator operator+(__iterator __i, difference_type __n)
requires __advanceable<_Start>
{
__i += __n;
return __i;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr __iterator operator+(difference_type __n, __iterator __i)
requires __advanceable<_Start>
{
return __i + __n;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr __iterator operator-(__iterator __i, difference_type __n)
requires __advanceable<_Start>
{
__i -= __n;
return __i;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y)
requires __advanceable<_Start>
{
if constexpr (__integer_like<_Start>) {
if constexpr (__signed_integer_like<_Start>) {
return difference_type(difference_type(__x.__value_) - difference_type(__y.__value_));
}
if (__y.__value_ > __x.__value_) {
return difference_type(-difference_type(__y.__value_ - __x.__value_));
}
return difference_type(__x.__value_ - __y.__value_);
}
return __x.__value_ - __y.__value_;
}
};
struct __sentinel {
friend class iota_view;
private:
_BoundSentinel __bound_sentinel_ = _BoundSentinel();
public:
_LIBCPP_HIDE_FROM_ABI
__sentinel() = default;
constexpr explicit __sentinel(_BoundSentinel __bound_sentinel) : __bound_sentinel_(std::move(__bound_sentinel)) {}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator==(const __iterator& __x, const __sentinel& __y) {
return __x.__value_ == __y.__bound_sentinel_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr iter_difference_t<_Start> operator-(const __iterator& __x, const __sentinel& __y)
requires sized_sentinel_for<_BoundSentinel, _Start>
{
return __x.__value_ - __y.__bound_sentinel_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr iter_difference_t<_Start> operator-(const __sentinel& __x, const __iterator& __y)
requires sized_sentinel_for<_BoundSentinel, _Start>
{
return -(__y - __x);
}
};
_Start __value_ = _Start();
_BoundSentinel __bound_sentinel_ = _BoundSentinel();
public:
_LIBCPP_HIDE_FROM_ABI
iota_view() requires default_initializable<_Start> = default;
_LIBCPP_HIDE_FROM_ABI
constexpr explicit iota_view(_Start __value) : __value_(std::move(__value)) { }
_LIBCPP_HIDE_FROM_ABI
constexpr iota_view(type_identity_t<_Start> __value, type_identity_t<_BoundSentinel> __bound_sentinel)
: __value_(std::move(__value)), __bound_sentinel_(std::move(__bound_sentinel)) {
// Validate the precondition if possible.
if constexpr (totally_ordered_with<_Start, _BoundSentinel>) {
_LIBCPP_ASSERT(ranges::less_equal()(__value_, __bound_sentinel_),
"Precondition violated: value is greater than bound.");
}
}
_LIBCPP_HIDE_FROM_ABI
constexpr iota_view(__iterator __first, __iterator __last)
requires same_as<_Start, _BoundSentinel>
: iota_view(std::move(__first.__value_), std::move(__last.__value_)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr iota_view(__iterator __first, _BoundSentinel __last)
requires same_as<_BoundSentinel, unreachable_sentinel_t>
: iota_view(std::move(__first.__value_), std::move(__last)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr iota_view(__iterator __first, __sentinel __last)
requires(!same_as<_Start, _BoundSentinel> && !same_as<_Start, unreachable_sentinel_t>)
: iota_view(std::move(__first.__value_), std::move(__last.__bound_sentinel_)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator begin() const { return __iterator{__value_}; }
_LIBCPP_HIDE_FROM_ABI
constexpr auto end() const {
if constexpr (same_as<_BoundSentinel, unreachable_sentinel_t>)
return unreachable_sentinel;
else
return __sentinel{__bound_sentinel_};
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator end() const
requires same_as<_Start, _BoundSentinel>
{
return __iterator{__bound_sentinel_};
}
_LIBCPP_HIDE_FROM_ABI
constexpr auto size() const
requires(same_as<_Start, _BoundSentinel> && __advanceable<_Start>) ||
(integral<_Start> && integral<_BoundSentinel>) || sized_sentinel_for<_BoundSentinel, _Start>
{
if constexpr (__integer_like<_Start> && __integer_like<_BoundSentinel>) {
if (__value_ < 0) {
if (__bound_sentinel_ < 0) {
return std::__to_unsigned_like(-__value_) - std::__to_unsigned_like(-__bound_sentinel_);
}
return std::__to_unsigned_like(__bound_sentinel_) + std::__to_unsigned_like(-__value_);
}
return std::__to_unsigned_like(__bound_sentinel_) - std::__to_unsigned_like(__value_);
}
return std::__to_unsigned_like(__bound_sentinel_ - __value_);
}
};
template <class _Start, class _BoundSentinel>
requires(!__integer_like<_Start> || !__integer_like<_BoundSentinel> ||
(__signed_integer_like<_Start> == __signed_integer_like<_BoundSentinel>))
iota_view(_Start, _BoundSentinel) -> iota_view<_Start, _BoundSentinel>;
template <class _Start, class _BoundSentinel>
inline constexpr bool enable_borrowed_range<iota_view<_Start, _BoundSentinel>> = true;
namespace views {
namespace __iota {
struct __fn {
template<class _Start>
_LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Start&& __start) const
noexcept(noexcept(ranges::iota_view(std::forward<_Start>(__start))))
-> decltype( ranges::iota_view(std::forward<_Start>(__start)))
{ return ranges::iota_view(std::forward<_Start>(__start)); }
template <class _Start, class _BoundSentinel>
_LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Start&& __start, _BoundSentinel&& __bound_sentinel) const
noexcept(noexcept(ranges::iota_view(std::forward<_Start>(__start), std::forward<_BoundSentinel>(__bound_sentinel))))
-> decltype( ranges::iota_view(std::forward<_Start>(__start), std::forward<_BoundSentinel>(__bound_sentinel)))
{ return ranges::iota_view(std::forward<_Start>(__start), std::forward<_BoundSentinel>(__bound_sentinel)); }
};
} // namespace __iota
inline namespace __cpo {
inline constexpr auto iota = __iota::__fn{};
} // namespace __cpo
} // namespace views
} // namespace ranges
#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___RANGES_IOTA_VIEW_H
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