llvm-project/libcxx/include/__ranges/transform_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_TRANSFORM_VIEW_H
#define _LIBCPP___RANGES_TRANSFORM_VIEW_H
#include <__compare/three_way_comparable.h>
#include <__concepts/constructible.h>
#include <__concepts/convertible_to.h>
#include <__concepts/copyable.h>
#include <__concepts/derived_from.h>
#include <__concepts/equality_comparable.h>
#include <__concepts/invocable.h>
#include <__config>
#include <__functional/bind_back.h>
#include <__functional/invoke.h>
#include <__iterator/concepts.h>
#include <__iterator/iter_swap.h>
#include <__iterator/iterator_traits.h>
#include <__memory/addressof.h>
#include <__ranges/access.h>
#include <__ranges/all.h>
#include <__ranges/concepts.h>
#include <__ranges/copyable_box.h>
#include <__ranges/empty.h>
#include <__ranges/range_adaptor.h>
#include <__ranges/size.h>
#include <__ranges/view_interface.h>
#include <__utility/forward.h>
#include <__utility/in_place.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 !defined(_LIBCPP_HAS_NO_RANGES)
namespace ranges {
template<class _View, class _Fn>
concept __transform_view_constraints =
view<_View> && is_object_v<_Fn> &&
regular_invocable<_Fn&, range_reference_t<_View>> &&
__referenceable<invoke_result_t<_Fn&, range_reference_t<_View>>>;
template<input_range _View, copy_constructible _Fn>
requires __transform_view_constraints<_View, _Fn>
class transform_view : public view_interface<transform_view<_View, _Fn>> {
template<bool> class __iterator;
template<bool> class __sentinel;
[[no_unique_address]] __copyable_box<_Fn> __func_;
[[no_unique_address]] _View __base_ = _View();
public:
_LIBCPP_HIDE_FROM_ABI
transform_view()
requires default_initializable<_View> && default_initializable<_Fn> = default;
_LIBCPP_HIDE_FROM_ABI
constexpr transform_view(_View __base, _Fn __func)
: __func_(_VSTD::in_place, _VSTD::move(__func)), __base_(_VSTD::move(__base)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr _View base() const& requires copy_constructible<_View> { return __base_; }
_LIBCPP_HIDE_FROM_ABI
constexpr _View base() && { return _VSTD::move(__base_); }
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator<false> begin() {
return __iterator<false>{*this, ranges::begin(__base_)};
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator<true> begin() const
requires range<const _View> &&
regular_invocable<const _Fn&, range_reference_t<const _View>>
{
return __iterator<true>(*this, ranges::begin(__base_));
}
_LIBCPP_HIDE_FROM_ABI
constexpr __sentinel<false> end() {
return __sentinel<false>(ranges::end(__base_));
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator<false> end()
requires common_range<_View>
{
return __iterator<false>(*this, ranges::end(__base_));
}
_LIBCPP_HIDE_FROM_ABI
constexpr __sentinel<true> end() const
requires range<const _View> &&
regular_invocable<const _Fn&, range_reference_t<const _View>>
{
return __sentinel<true>(ranges::end(__base_));
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator<true> end() const
requires common_range<const _View> &&
regular_invocable<const _Fn&, range_reference_t<const _View>>
{
return __iterator<true>(*this, ranges::end(__base_));
}
_LIBCPP_HIDE_FROM_ABI
constexpr auto size() requires sized_range<_View> { return ranges::size(__base_); }
_LIBCPP_HIDE_FROM_ABI
constexpr auto size() const requires sized_range<const _View> { return ranges::size(__base_); }
};
template<class _Range, class _Fn>
transform_view(_Range&&, _Fn) -> transform_view<views::all_t<_Range>, _Fn>;
template<class _View>
struct __transform_view_iterator_concept { using type = input_iterator_tag; };
template<random_access_range _View>
struct __transform_view_iterator_concept<_View> { using type = random_access_iterator_tag; };
template<bidirectional_range _View>
struct __transform_view_iterator_concept<_View> { using type = bidirectional_iterator_tag; };
template<forward_range _View>
struct __transform_view_iterator_concept<_View> { using type = forward_iterator_tag; };
template<class, class>
struct __transform_view_iterator_category_base {};
template<forward_range _View, class _Fn>
struct __transform_view_iterator_category_base<_View, _Fn> {
using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category;
using iterator_category = conditional_t<
is_lvalue_reference_v<invoke_result_t<_Fn&, range_reference_t<_View>>>,
conditional_t<
derived_from<_Cat, contiguous_iterator_tag>,
random_access_iterator_tag,
_Cat
>,
input_iterator_tag
>;
};
template<input_range _View, copy_constructible _Fn>
requires __transform_view_constraints<_View, _Fn>
template<bool _Const>
class transform_view<_View, _Fn>::__iterator
: public __transform_view_iterator_category_base<_View, _Fn> {
using _Parent = __maybe_const<_Const, transform_view>;
using _Base = __maybe_const<_Const, _View>;
_Parent *__parent_ = nullptr;
template<bool>
friend class transform_view<_View, _Fn>::__iterator;
template<bool>
friend class transform_view<_View, _Fn>::__sentinel;
public:
iterator_t<_Base> __current_ = iterator_t<_Base>();
using iterator_concept = typename __transform_view_iterator_concept<_View>::type;
using value_type = remove_cvref_t<invoke_result_t<_Fn&, range_reference_t<_Base>>>;
using difference_type = range_difference_t<_Base>;
_LIBCPP_HIDE_FROM_ABI
__iterator() requires default_initializable<iterator_t<_Base>> = default;
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator(_Parent& __parent, iterator_t<_Base> __current)
: __parent_(_VSTD::addressof(__parent)), __current_(_VSTD::move(__current)) {}
// Note: `__i` should always be `__iterator<false>`, but directly using
// `__iterator<false>` is ill-formed when `_Const` is false
// (see http://wg21.link/class.copy.ctor#5).
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator(__iterator<!_Const> __i)
requires _Const && convertible_to<iterator_t<_View>, iterator_t<_Base>>
: __parent_(__i.__parent_), __current_(_VSTD::move(__i.__current_)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr iterator_t<_Base> base() const&
requires copyable<iterator_t<_Base>>
{
return __current_;
}
_LIBCPP_HIDE_FROM_ABI
constexpr iterator_t<_Base> base() && {
return _VSTD::move(__current_);
}
_LIBCPP_HIDE_FROM_ABI
constexpr decltype(auto) operator*() const
noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, *__current_)))
{
return _VSTD::invoke(*__parent_->__func_, *__current_);
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator++() {
++__current_;
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr void operator++(int) { ++__current_; }
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator operator++(int)
requires forward_range<_Base>
{
auto __tmp = *this;
++*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator--()
requires bidirectional_range<_Base>
{
--__current_;
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator operator--(int)
requires bidirectional_range<_Base>
{
auto __tmp = *this;
--*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator+=(difference_type __n)
requires random_access_range<_Base>
{
__current_ += __n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr __iterator& operator-=(difference_type __n)
requires random_access_range<_Base>
{
__current_ -= __n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI
constexpr decltype(auto) operator[](difference_type __n) const
noexcept(noexcept(_VSTD::invoke(*__parent_->__func_, __current_[__n])))
requires random_access_range<_Base>
{
return _VSTD::invoke(*__parent_->__func_, __current_[__n]);
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
requires equality_comparable<iterator_t<_Base>>
{
return __x.__current_ == __y.__current_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator<(const __iterator& __x, const __iterator& __y)
requires random_access_range<_Base>
{
return __x.__current_ < __y.__current_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator>(const __iterator& __x, const __iterator& __y)
requires random_access_range<_Base>
{
return __x.__current_ > __y.__current_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator<=(const __iterator& __x, const __iterator& __y)
requires random_access_range<_Base>
{
return __x.__current_ <= __y.__current_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator>=(const __iterator& __x, const __iterator& __y)
requires random_access_range<_Base>
{
return __x.__current_ >= __y.__current_;
}
#if !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
_LIBCPP_HIDE_FROM_ABI
friend constexpr auto operator<=>(const __iterator& __x, const __iterator& __y)
requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>>
{
return __x.__current_ <=> __y.__current_;
}
#endif // !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR)
_LIBCPP_HIDE_FROM_ABI
friend constexpr __iterator operator+(__iterator __i, difference_type __n)
requires random_access_range<_Base>
{
return __iterator{*__i.__parent_, __i.__current_ + __n};
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr __iterator operator+(difference_type __n, __iterator __i)
requires random_access_range<_Base>
{
return __iterator{*__i.__parent_, __i.__current_ + __n};
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr __iterator operator-(__iterator __i, difference_type __n)
requires random_access_range<_Base>
{
return __iterator{*__i.__parent_, __i.__current_ - __n};
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr difference_type operator-(const __iterator& __x, const __iterator& __y)
requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
{
return __x.__current_ - __y.__current_;
}
_LIBCPP_HIDE_FROM_ABI
friend constexpr decltype(auto) iter_move(const __iterator& __i)
noexcept(noexcept(*__i))
{
if constexpr (is_lvalue_reference_v<decltype(*__i)>)
return _VSTD::move(*__i);
else
return *__i;
}
};
template<input_range _View, copy_constructible _Fn>
requires __transform_view_constraints<_View, _Fn>
template<bool _Const>
class transform_view<_View, _Fn>::__sentinel {
using _Parent = __maybe_const<_Const, transform_view>;
using _Base = __maybe_const<_Const, _View>;
sentinel_t<_Base> __end_ = sentinel_t<_Base>();
template<bool>
friend class transform_view<_View, _Fn>::__iterator;
template<bool>
friend class transform_view<_View, _Fn>::__sentinel;
public:
_LIBCPP_HIDE_FROM_ABI
__sentinel() = default;
_LIBCPP_HIDE_FROM_ABI
constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(__end) {}
// Note: `__i` should always be `__sentinel<false>`, but directly using
// `__sentinel<false>` is ill-formed when `_Const` is false
// (see http://wg21.link/class.copy.ctor#5).
_LIBCPP_HIDE_FROM_ABI
constexpr __sentinel(__sentinel<!_Const> __i)
requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
: __end_(_VSTD::move(__i.__end_)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr sentinel_t<_Base> base() const { return __end_; }
template<bool _OtherConst>
requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
_LIBCPP_HIDE_FROM_ABI
friend constexpr bool operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
return __x.__current_ == __y.__end_;
}
template<bool _OtherConst>
requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
_LIBCPP_HIDE_FROM_ABI
friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
operator-(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
return __x.__current_ - __y.__end_;
}
template<bool _OtherConst>
requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
_LIBCPP_HIDE_FROM_ABI
friend constexpr range_difference_t<__maybe_const<_OtherConst, _View>>
operator-(const __sentinel& __x, const __iterator<_OtherConst>& __y) {
return __x.__end_ - __y.__current_;
}
};
namespace views {
namespace __transform {
struct __fn {
template<class _Range, class _Fn>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Range&& __range, _Fn&& __f) const
noexcept(noexcept(transform_view(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f))))
-> decltype( transform_view(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f)))
{ return transform_view(_VSTD::forward<_Range>(__range), _VSTD::forward<_Fn>(__f)); }
template<class _Fn>
requires constructible_from<decay_t<_Fn>, _Fn>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Fn&& __f) const
noexcept(is_nothrow_constructible_v<decay_t<_Fn>, _Fn>)
{ return __range_adaptor_closure_t(_VSTD::__bind_back(*this, _VSTD::forward<_Fn>(__f))); }
};
}
inline namespace __cpo {
inline constexpr auto transform = __transform::__fn{};
}
} // namespace views
} // namespace ranges
#endif // !defined(_LIBCPP_HAS_NO_RANGES)
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___RANGES_TRANSFORM_VIEW_H