[libcxx-commits] [libcxx] [libc++] P3168R2 Give std::optional Range Support (PR #146491)

[via libcxx-commits]

================
@@ -578,6 +593,128 @@ struct __is_std_optional : false_type {};
 template <class _Tp>
 struct __is_std_optional<optional<_Tp>> : true_type {};
 
+#    if _LIBCPP_STD_VER >= 26
+
+template <class _T>
+constexpr bool ranges::enable_view<optional<_T>> = true;
+
+template <class _T>
+constexpr auto format_kind<optional<_T>> = range_format::disabled;
+
+template <typename _Tp>
+class __optional_iterator {
+  using _Base = __wrap_iter<_Tp*>;
+  _Base __it_;
+
+public:
+  using value_type        = _Tp;
+  using difference_type   = typename _Base::difference_type;
+  using pointer           = typename _Base::pointer;
+  using reference         = typename _Base::reference;
+  using iterator_category = random_access_iterator_tag;
+  using iterator_concept  = contiguous_iterator_tag;
+
+private:
+  _LIBCPP_HIDE_FROM_ABI constexpr explicit __optional_iterator(_Base __it) noexcept : __it_(__it) {}
+
+  _LIBCPP_HIDE_FROM_ABI friend class __wrap_iter<_Tp*>;
+  _LIBCPP_HIDE_FROM_ABI friend class __wrap_iter<const _Tp*>;
+
+  _LIBCPP_HIDE_FROM_ABI friend class optional<std::remove_const_t<_Tp>>;
+  _LIBCPP_HIDE_FROM_ABI friend class optional<const _Tp>;
+
+public:
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator() : __it_(_Base()) {}
+
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator(const __optional_iterator&)            = default;
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator& operator=(const __optional_iterator&) = default;
+
+  _LIBCPP_HIDE_FROM_ABI constexpr reference operator*() const { return *__it_; }
+  _LIBCPP_HIDE_FROM_ABI constexpr pointer operator->() const { return __it_.operator->(); } 
+
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator& operator++() noexcept {
+    ++__it_;
+    return *this;
+  }
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator operator++(int) noexcept {
+    auto __tmp = *this;
+    ++__it_;
+    return __tmp;
+  }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator& operator--() noexcept {
+    --__it_;
+    return *this;
+  }
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator operator--(int) noexcept {
+    auto __tmp = *this;
+    --__it_;
+    return __tmp;
+  }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator& operator+=(difference_type __n) noexcept {
+    __it_ += __n;
+    return *this;
+  }
+  _LIBCPP_HIDE_FROM_ABI constexpr __optional_iterator& operator-=(difference_type __n) noexcept {
+    __it_ -= __n;
+    return *this;
+  }
+
+  _LIBCPP_HIDE_FROM_ABI friend constexpr __optional_iterator
+  operator+(__optional_iterator __i, difference_type __n) noexcept {
+    return __optional_iterator(__i.__it_ + __n);
+  }
+  _LIBCPP_HIDE_FROM_ABI friend constexpr __optional_iterator
+  operator+(difference_type __n, __optional_iterator __i) noexcept {
+    return __i + __n;
+  }
+  _LIBCPP_HIDE_FROM_ABI friend constexpr __optional_iterator
+  operator-(__optional_iterator __i, difference_type __n) noexcept {
+    return __optional_iterator(__i.__it_ - __n);
+  }
+  _LIBCPP_HIDE_FROM_ABI friend constexpr difference_type
+  operator-(__optional_iterator __a, __optional_iterator __b) noexcept {
+    return __a.__it_ - __b.__it_;
+  }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr reference operator[](difference_type __n) const noexcept { return *(__it_ + __n); }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr bool operator==(const __optional_iterator& __other) const {
+    return __it_ == __other.__it_;
+  }
+
+  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
+  operator<(const __optional_iterator& __a, const __optional_iterator& __b) noexcept {
+    return __a.__it_ < __b.__it_;
+  }
+  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
+  operator>(const __optional_iterator& __a, const __optional_iterator& __b) noexcept {
+    return __a.__it_ > __b.__it_;
+  }
+  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
+  operator<=(const __optional_iterator& __a, const __optional_iterator& __b) noexcept {
+    return __a.__it_ <= __b.__it_;
+  }
+  _LIBCPP_HIDE_FROM_ABI friend constexpr bool
+  operator>=(const __optional_iterator& __a, const __optional_iterator& __b) noexcept {
+    return __a.__it_ >= __b.__it_;
+  }
+
+  template <typename _Ut = _Tp>
+  _LIBCPP_HIDE_FROM_ABI constexpr operator __optional_iterator<const _Tp>() const
+    requires(!std::is_const_v<_Ut>)
+  {
+    return __optional_iterator<const _Tp>(__wrap_iter<const _Tp*>{__it_.base()});
+  }
+};
+template <typename _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp* to_address(const __optional_iterator<_Tp>& __it) noexcept {
+  return std::to_address(__it.__it_);
+}
----------------
dywoq wrote:

Sorry

https://github.com/llvm/llvm-project/pull/146491