constexpr basic_string_view() noexcept;
constexpr basic_string_view(const charT* str);
constexpr basic_string_view(const charT* str, size_type len);
template<class It, class End>
constexpr basic_string_view(It begin, End end);
template<class R>
constexpr explicit basic_string_view(R&& r);
template<class It, class End>
basic_string_view(It, End) -> basic_string_view<iter_value_t<It>>;
template<class R>
basic_string_view(R&&) -> basic_string_view<ranges::range_value_t<R>>;
constexpr const_iterator begin() const noexcept;
constexpr const_iterator cbegin() const noexcept;
constexpr const_iterator end() const noexcept;
constexpr const_iterator cend() const noexcept;
constexpr const_reverse_iterator rbegin() const noexcept;
constexpr const_reverse_iterator crbegin() const noexcept;
constexpr const_reverse_iterator rend() const noexcept;
constexpr const_reverse_iterator crend() const noexcept;
constexpr size_type size() const noexcept;
constexpr size_type length() const noexcept;
constexpr size_type max_size() const noexcept;
[[nodiscard]] constexpr bool empty() const noexcept;
constexpr const_reference operator[](size_type pos) const;
constexpr const_reference at(size_type pos) const;
constexpr const_reference front() const;
constexpr const_reference back() const;
constexpr const_pointer data() const noexcept;
constexpr void remove_prefix(size_type n);
constexpr void remove_suffix(size_type n);
constexpr void swap(basic_string_view& s) noexcept;
constexpr size_type copy(charT* s, size_type n, size_type pos = 0) const;
constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
constexpr int compare(basic_string_view str) const noexcept;
constexpr int compare(size_type pos1, size_type n1, basic_string_view str) const;
constexpr int compare(size_type pos1, size_type n1, basic_string_view str,
size_type pos2, size_type n2) const;
constexpr int compare(const charT* s) const;
constexpr int compare(size_type pos1, size_type n1, const charT* s) const;
constexpr int compare(size_type pos1, size_type n1, const charT* s, size_type n2) const;
constexpr bool starts_with(basic_string_view x) const noexcept;
constexpr bool starts_with(charT x) const noexcept;
constexpr bool starts_with(const charT* x) const;
constexpr bool ends_with(basic_string_view x) const noexcept;
constexpr bool ends_with(charT x) const noexcept;
constexpr bool ends_with(const charT* x) const;
constexpr bool contains(basic_string_view x) const noexcept;
constexpr bool contains(charT x) const noexcept;
constexpr bool contains(const charT* x) const;
constexpr size_type find(basic_string_view str, size_type pos = 0) const noexcept;
constexpr size_type rfind(basic_string_view str, size_type pos = npos) const noexcept;
constexpr size_type find_first_of(basic_string_view str, size_type pos = 0) const noexcept;
constexpr size_type find_last_of(basic_string_view str, size_type pos = npos) const noexcept;
constexpr size_type find_first_not_of(basic_string_view str, size_type pos = 0) const noexcept;
constexpr size_type find_last_not_of(basic_string_view str, size_type pos = npos) const noexcept;