21 Strings library [strings]

21.4 String view classes [string.view]

21.4.3 Class template basic_­string_­view [string.view.template]

21.4.3.1 General [string.view.template.general]

namespace std { template<class charT, class traits = char_traits<charT>> class basic_string_view { public: // types using traits_type = traits; using value_type = charT; using pointer = value_type*; using const_pointer = const value_type*; using reference = value_type&; using const_reference = const value_type&; using const_iterator = implementation-defined; // see [string.view.iterators] using iterator = const_iterator;226 using const_reverse_iterator = reverse_iterator<const_iterator>; using reverse_iterator = const_reverse_iterator; using size_type = size_t; using difference_type = ptrdiff_t; static constexpr size_type npos = size_type(-1); // [string.view.cons], construction and assignment constexpr basic_string_view() noexcept; constexpr basic_string_view(const basic_string_view&) noexcept = default; constexpr basic_string_view& operator=(const basic_string_view&) noexcept = default; 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); // [string.view.iterators], iterator support constexpr const_iterator begin() const noexcept; constexpr const_iterator end() const noexcept; constexpr const_iterator cbegin() const noexcept; constexpr const_iterator cend() const noexcept; constexpr const_reverse_iterator rbegin() const noexcept; constexpr const_reverse_iterator rend() const noexcept; constexpr const_reverse_iterator crbegin() const noexcept; constexpr const_reverse_iterator crend() const noexcept; // [string.view.capacity], capacity 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; // [string.view.access], element access 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; // [string.view.modifiers], modifiers constexpr void remove_prefix(size_type n); constexpr void remove_suffix(size_type n); constexpr void swap(basic_string_view& s) noexcept; // [string.view.ops], string operations 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 s) const noexcept; constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const; constexpr int compare(size_type pos1, size_type n1, basic_string_view s, 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; // [string.view.find], searching constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept; constexpr size_type find(charT c, size_type pos = 0) const noexcept; constexpr size_type find(const charT* s, size_type pos, size_type n) const; constexpr size_type find(const charT* s, size_type pos = 0) const; constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept; constexpr size_type rfind(charT c, size_type pos = npos) const noexcept; constexpr size_type rfind(const charT* s, size_type pos, size_type n) const; constexpr size_type rfind(const charT* s, size_type pos = npos) const; constexpr size_type find_first_of(basic_string_view s, size_type pos = 0) const noexcept; constexpr size_type find_first_of(charT c, size_type pos = 0) const noexcept; constexpr size_type find_first_of(const charT* s, size_type pos, size_type n) const; constexpr size_type find_first_of(const charT* s, size_type pos = 0) const; constexpr size_type find_last_of(basic_string_view s, size_type pos = npos) const noexcept; constexpr size_type find_last_of(charT c, size_type pos = npos) const noexcept; constexpr size_type find_last_of(const charT* s, size_type pos, size_type n) const; constexpr size_type find_last_of(const charT* s, size_type pos = npos) const; constexpr size_type find_first_not_of(basic_string_view s, size_type pos = 0) const noexcept; constexpr size_type find_first_not_of(charT c, size_type pos = 0) const noexcept; constexpr size_type find_first_not_of(const charT* s, size_type pos, size_type n) const; constexpr size_type find_first_not_of(const charT* s, size_type pos = 0) const; constexpr size_type find_last_not_of(basic_string_view s, size_type pos = npos) const noexcept; constexpr size_type find_last_not_of(charT c, size_type pos = npos) const noexcept; constexpr size_type find_last_not_of(const charT* s, size_type pos, size_type n) const; constexpr size_type find_last_not_of(const charT* s, size_type pos = npos) const; private: const_pointer data_; // exposition only size_type size_; // exposition only }; // [string.view.deduct], deduction guide template<class It, class End> basic_string_view(It, End) -> basic_string_view<iter_value_t<It>>; }
In every specialization basic_­string_­view<charT, traits>, the type traits shall meet the character traits requirements ([char.traits]).
[Note 1:
The program is ill-formed if traits​::​char_­type is not the same type as charT.
— end note]
For a basic_­string_­view str, any operation that invalidates a pointer in the range [str.data(), ​str.data() + str.size()) invalidates pointers, iterators, and references returned from str's member functions.
The complexity of basic_­string_­view member functions is unless otherwise specified.
Because basic_­string_­view refers to a constant sequence, iterator and const_­iterator are the same type.