implement `std::views::istream`
implement `std::ranges::basic_istream_view` and `std::views::istream`. Although the view itself is constexpr,
the constructor argument is a base class std::istream where its ctor/dtor are not constexpr. So no tests are performed in
constexpr
Differential Revision: https://reviews.llvm.org/D133317
NOKEYCHECK=True
GitOrigin-RevId: 96a509bca28b8668c3c2c68aae4116cc0d8c2952
diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index 8e79e10..b9b657b 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -481,6 +481,7 @@
__ranges/enable_view.h
__ranges/filter_view.h
__ranges/iota_view.h
+ __ranges/istream_view.h
__ranges/join_view.h
__ranges/lazy_split_view.h
__ranges/non_propagating_cache.h
diff --git a/include/__ranges/istream_view.h b/include/__ranges/istream_view.h
new file mode 100644
index 0000000..caa29aa
--- /dev/null
+++ b/include/__ranges/istream_view.h
@@ -0,0 +1,139 @@
+// -*- 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_ISTREAM_VIEW_H
+#define _LIBCPP___RANGES_ISTREAM_VIEW_H
+
+#include <__concepts/constructible.h>
+#include <__concepts/derived_from.h>
+#include <__concepts/movable.h>
+#include <__config>
+#include <__iterator/default_sentinel.h>
+#include <__iterator/iterator_traits.h>
+#include <__memory/addressof.h>
+#include <__ranges/view_interface.h>
+#include <__type_traits/remove_cvref.h>
+#include <__utility/forward.h>
+#include <cstddef>
+#include <iosfwd>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 20
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+
+template <class _Val, class _CharT, class _Traits>
+concept __stream_extractable = requires(basic_istream<_CharT, _Traits>& __is, _Val& __t) { __is >> __t; };
+
+template <movable _Val, class _CharT, class _Traits = char_traits<_CharT>>
+ requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>
+class basic_istream_view : public view_interface<basic_istream_view<_Val, _CharT, _Traits>> {
+public:
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
+ : __stream_(std::addressof(__stream)) {}
+
+ _LIBCPP_HIDE_FROM_ABI constexpr auto begin() {
+ *__stream_ >> __value_;
+ return __iterator{*this};
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr default_sentinel_t end() const noexcept { return default_sentinel; }
+
+private:
+ class __iterator;
+
+ basic_istream<_CharT, _Traits>* __stream_;
+ _LIBCPP_NO_UNIQUE_ADDRESS _Val __value_ = _Val();
+};
+
+template <movable _Val, class _CharT, class _Traits>
+ requires default_initializable<_Val> && __stream_extractable<_Val, _CharT, _Traits>
+class basic_istream_view<_Val, _CharT, _Traits>::__iterator {
+public:
+ using iterator_concept = input_iterator_tag;
+ using difference_type = ptrdiff_t;
+ using value_type = _Val;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(basic_istream_view& __parent) noexcept
+ : __parent_(std::addressof(__parent)) {}
+
+ __iterator(const __iterator&) = delete;
+ _LIBCPP_HIDE_FROM_ABI __iterator(__iterator&&) = default;
+
+ __iterator& operator=(const __iterator&) = delete;
+ _LIBCPP_HIDE_FROM_ABI __iterator& operator=(__iterator&&) = default;
+
+ _LIBCPP_HIDE_FROM_ABI __iterator& operator++() {
+ *__parent_->__stream_ >> __parent_->__value_;
+ return *this;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI void operator++(int) { ++*this; }
+
+ _LIBCPP_HIDE_FROM_ABI _Val& operator*() const { return __parent_->__value_; }
+
+ _LIBCPP_HIDE_FROM_ABI friend bool operator==(const __iterator& __x, default_sentinel_t) {
+ return !*__x.__get_parent_stream();
+ }
+
+private:
+ basic_istream_view* __parent_;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr basic_istream<_CharT, _Traits>* __get_parent_stream() const {
+ return __parent_->__stream_;
+ }
+};
+
+template <class _Val>
+using istream_view = basic_istream_view<_Val, char>;
+
+#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+template <class _Val>
+using wistream_view = basic_istream_view<_Val, wchar_t>;
+#endif
+
+namespace views {
+namespace __istream {
+
+// clang-format off
+template <class _Tp>
+struct __fn {
+ template <class _Up, class _UnCVRef = remove_cvref_t<_Up>>
+ requires derived_from<_UnCVRef, basic_istream<typename _UnCVRef::char_type,
+ typename _UnCVRef::traits_type>>
+ _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Up&& __u) const
+ noexcept(noexcept(basic_istream_view<_Tp, typename _UnCVRef::char_type,
+ typename _UnCVRef::traits_type>(std::forward<_Up>(__u))))
+ -> decltype( basic_istream_view<_Tp, typename _UnCVRef::char_type,
+ typename _UnCVRef::traits_type>(std::forward<_Up>(__u)))
+ { return basic_istream_view<_Tp, typename _UnCVRef::char_type,
+ typename _UnCVRef::traits_type>(std::forward<_Up>(__u));
+ }
+};
+// clang-format on
+
+} // namespace __istream
+
+inline namespace __cpo {
+template <class _Tp>
+ inline constexpr auto istream = __istream::__fn<_Tp>{};
+} // namespace __cpo
+} // namespace views
+
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 20
+
+#endif // _LIBCPP___RANGES_ISTREAM_VIEW_H
diff --git a/include/module.modulemap.in b/include/module.modulemap.in
index dd7fd08..73e366f 100644
--- a/include/module.modulemap.in
+++ b/include/module.modulemap.in
@@ -1014,6 +1014,10 @@
module enable_view { private header "__ranges/enable_view.h" }
module filter_view { private header "__ranges/filter_view.h" }
module iota_view { private header "__ranges/iota_view.h" }
+ module istream_view {
+ @requires_LIBCXX_ENABLE_LOCALIZATION@
+ private header "__ranges/istream_view.h"
+ }
module join_view { private header "__ranges/join_view.h" }
module lazy_split_view { private header "__ranges/lazy_split_view.h" }
module non_propagating_cache { private header "__ranges/non_propagating_cache.h" }
diff --git a/include/ranges b/include/ranges
index b2e14cd..0565b2f 100644
--- a/include/ranges
+++ b/include/ranges
@@ -228,6 +228,19 @@
inline constexpr unspecified lazy_split = unspecified;
}
+ // [range.istream], istream view
+ template<movable Val, class CharT, class Traits = char_traits<CharT>>
+ requires see below
+ class basic_istream_view;
+
+ template<class Val>
+ using istream_view = basic_istream_view<Val, char>;
+
+ template<class Val>
+ using wistream_view = basic_istream_view<Val, wchar_t>;
+
+ namespace views { template<class T> inline constexpr unspecified istream = unspecified; }
+
// [range.zip], zip view
template<input_range... Views>
requires (view<Views> && ...) && (sizeof...(Views) > 0)
@@ -305,6 +318,10 @@
#include <type_traits>
#include <version>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <__ranges/istream_view.h>
+#endif
+
// standard-mandated includes
// [ranges.syn]