9783f28cbb
This patch runs clang-format on all of libcxx/include and libcxx/src, in
accordance with the RFC discussed at [1]. Follow-up patches will format
the benchmarks, the test suite and remaining parts of the code. I'm
splitting this one into its own patch so the diff is a bit easier to
review.
This patch was generated with:
find libcxx/include libcxx/src -type f \
| grep -v 'module.modulemap.in' \
| grep -v 'CMakeLists.txt' \
| grep -v 'README.txt' \
| grep -v 'libcxx.imp' \
| grep -v '__config_site.in' \
| xargs clang-format -i
A Git merge driver is available in libcxx/utils/clang-format-merge-driver.sh
to help resolve merge and rebase issues across these formatting changes.
[1]: https://discourse.llvm.org/t/rfc-clang-formatting-all-of-libc-once-and-for-all
104 lines
3.5 KiB
C++
104 lines
3.5 KiB
C++
// -*- 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_NON_PROPAGATING_CACHE_H
|
|
#define _LIBCPP___RANGES_NON_PROPAGATING_CACHE_H
|
|
|
|
#include <__config>
|
|
#include <__iterator/concepts.h> // indirectly_readable
|
|
#include <__iterator/iterator_traits.h> // iter_reference_t
|
|
#include <__memory/addressof.h>
|
|
#include <__utility/forward.h>
|
|
#include <optional>
|
|
|
|
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
|
|
# pragma GCC system_header
|
|
#endif
|
|
|
|
_LIBCPP_BEGIN_NAMESPACE_STD
|
|
|
|
#if _LIBCPP_STD_VER >= 20
|
|
|
|
namespace ranges {
|
|
// __non_propagating_cache is a helper type that allows storing an optional value in it,
|
|
// but which does not copy the source's value when it is copy constructed/assigned to,
|
|
// and which resets the source's value when it is moved-from.
|
|
//
|
|
// This type is used as an implementation detail of some views that need to cache the
|
|
// result of `begin()` in order to provide an amortized O(1) begin() method. Typically,
|
|
// we don't want to propagate the value of the cache upon copy because the cached iterator
|
|
// may refer to internal details of the source view.
|
|
template <class _Tp>
|
|
requires is_object_v<_Tp>
|
|
class _LIBCPP_TEMPLATE_VIS __non_propagating_cache {
|
|
struct __from_tag {};
|
|
struct __forward_tag {};
|
|
|
|
// This helper class is needed to perform copy and move elision when
|
|
// constructing the contained type from an iterator.
|
|
struct __wrapper {
|
|
template <class... _Args>
|
|
_LIBCPP_HIDE_FROM_ABI constexpr explicit __wrapper(__forward_tag, _Args&&... __args)
|
|
: __t_(std::forward<_Args>(__args)...) {}
|
|
template <class _Fn>
|
|
_LIBCPP_HIDE_FROM_ABI constexpr explicit __wrapper(__from_tag, _Fn const& __f) : __t_(__f()) {}
|
|
_Tp __t_;
|
|
};
|
|
|
|
optional<__wrapper> __value_ = nullopt;
|
|
|
|
public:
|
|
_LIBCPP_HIDE_FROM_ABI __non_propagating_cache() = default;
|
|
|
|
_LIBCPP_HIDE_FROM_ABI constexpr __non_propagating_cache(__non_propagating_cache const&) noexcept
|
|
: __value_(nullopt) {}
|
|
|
|
_LIBCPP_HIDE_FROM_ABI constexpr __non_propagating_cache(__non_propagating_cache&& __other) noexcept
|
|
: __value_(nullopt) {
|
|
__other.__value_.reset();
|
|
}
|
|
|
|
_LIBCPP_HIDE_FROM_ABI constexpr __non_propagating_cache& operator=(__non_propagating_cache const& __other) noexcept {
|
|
if (this != std::addressof(__other)) {
|
|
__value_.reset();
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
_LIBCPP_HIDE_FROM_ABI constexpr __non_propagating_cache& operator=(__non_propagating_cache&& __other) noexcept {
|
|
__value_.reset();
|
|
__other.__value_.reset();
|
|
return *this;
|
|
}
|
|
|
|
_LIBCPP_HIDE_FROM_ABI constexpr _Tp& operator*() { return __value_->__t_; }
|
|
_LIBCPP_HIDE_FROM_ABI constexpr _Tp const& operator*() const { return __value_->__t_; }
|
|
|
|
_LIBCPP_HIDE_FROM_ABI constexpr bool __has_value() const { return __value_.has_value(); }
|
|
|
|
template <class _Fn>
|
|
_LIBCPP_HIDE_FROM_ABI constexpr _Tp& __emplace_from(_Fn const& __f) {
|
|
return __value_.emplace(__from_tag{}, __f).__t_;
|
|
}
|
|
|
|
template <class... _Args>
|
|
_LIBCPP_HIDE_FROM_ABI constexpr _Tp& __emplace(_Args&&... __args) {
|
|
return __value_.emplace(__forward_tag{}, std::forward<_Args>(__args)...).__t_;
|
|
}
|
|
};
|
|
|
|
struct __empty_cache {};
|
|
} // namespace ranges
|
|
|
|
#endif // _LIBCPP_STD_VER >= 20
|
|
|
|
_LIBCPP_END_NAMESPACE_STD
|
|
|
|
#endif // _LIBCPP___RANGES_NON_PROPAGATING_CACHE_H
|