On 06/02/20 19:52 -0500, Patrick Palka wrote:
This patch adds ranges::basic_istream_view and ranges::istream_view. This seems
to be the last missing part of the ranges header.
libstdc++-v3/ChangeLog:
* include/std/ranges (ranges::__detail::__stream_extractable,
ranges::basic_istream_view, ranges::istream_view): Define.
* testsuite/std/ranges/istream_view: New test.
---
libstdc++-v3/include/std/ranges | 94 +++++++++++++++++++
.../testsuite/std/ranges/istream_view.cc | 76 +++++++++++++++
2 files changed, 170 insertions(+)
create mode 100644 libstdc++-v3/testsuite/std/ranges/istream_view.cc
diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 8a8fefb6f19..88b98310ef9 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -951,6 +951,100 @@ namespace views
inline constexpr _Iota iota{};
} // namespace views
+ namespace __detail
+ {
+ template<typename _Val, typename _CharT, typename _Traits>
+ concept __stream_extractable
+ = requires(basic_istream<_CharT, _Traits>& is, _Val& t) { is >> t; };
I was going to ask for "is" and "t" to use reserved names, but those
names are actually reserved. std::ctype::is is present since C++98 and
std::binomial_distribution::t() since C++11. So the names are OK.
+ } // namespace __detail
+
+ template<movable _Val, typename _CharT, typename _Traits>
+ requires default_initializable<_Val>
+ && __detail::__stream_extractable<_Val, _CharT, _Traits>
+ class basic_istream_view
+ : public view_interface<basic_istream_view<_Val, _CharT, _Traits>>
+ {
+ public:
+ basic_istream_view() = default;
+
+ constexpr explicit
+ basic_istream_view(basic_istream<_CharT, _Traits>& __stream)
+ : _M_stream(std::__addressof(__stream))
+ { }
+
+ constexpr auto
+ begin()
+ {
+ if (_M_stream != nullptr)
+ *_M_stream >> _M_object;
+ return _Iterator{*this};
+ }
+
+ constexpr default_sentinel_t
+ end() const noexcept
+ { return default_sentinel; }
+
+ private:
+ basic_istream<_CharT, _Traits>* _M_stream = nullptr;
+ _Val _M_object = _Val();
+
+ struct _Iterator
+ {
+ public:
+ using iterator_category = input_iterator_tag;
+ using difference_type = ptrdiff_t;
+ using value_type = _Val;
+
+ _Iterator() = default;
+
+ constexpr explicit
+ _Iterator(basic_istream_view& __parent) noexcept
+ : _M_parent(std::__addressof(__parent))
+ { }
+
+ _Iterator(const _Iterator&) = delete;
+ _Iterator(_Iterator&&) = default;
+ _Iterator& operator=(const _Iterator&) = delete;
+ _Iterator& operator=(_Iterator&&) = default;
+
+ _Iterator&
+ operator++()
+ {
+ __glibcxx_assert(_M_parent->_M_stream != nullptr);
+ *_M_parent->_M_stream >> _M_parent->_M_object;
+ }
+
+ void
+ operator++(int)
+ { ++*this; }
+
+ _Val&
+ operator*() const
+ {
+ __glibcxx_assert(_M_parent->_M_stream != nullptr);
+ return _M_parent->_M_object;
+ }
+
+ friend bool
+ operator==(const _Iterator& __x, default_sentinel_t)
+ { return __x.__at_end(); }
+
+ private:
+ basic_istream_view* _M_parent = nullptr;
+
+ bool
+ __at_end() const
Please rename this to _M_at_end for consistency with the rest of the
library.
OK for master with that tweak, thanks.
