// -*- 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_STRING
#define _LIBCPP_STRING

// clang-format off

/*
    string synopsis

#include <compare>
#include <initializer_list>

namespace std
{

template <class stateT>
class fpos
{
private:
    stateT st;
public:
    fpos(streamoff = streamoff());

    operator streamoff() const;

    stateT state() const;
    void state(stateT);

    fpos& operator+=(streamoff);
    fpos  operator+ (streamoff) const;
    fpos& operator-=(streamoff);
    fpos  operator- (streamoff) const;
};

template <class stateT> streamoff operator-(const fpos<stateT>& x, const fpos<stateT>& y);

template <class stateT> bool operator==(const fpos<stateT>& x, const fpos<stateT>& y);
template <class stateT> bool operator!=(const fpos<stateT>& x, const fpos<stateT>& y);

template <class charT>
struct char_traits
{
    using char_type           = charT;
    using int_type            = ...;
    using off_type            = streamoff;
    using pos_type            = streampos;
    using state_type          = mbstate_t;
    using comparison_category = strong_ordering; // Since C++20 only for the specializations
                                                 // char, wchar_t, char8_t, char16_t, and char32_t.

    static void assign(char_type& c1, const char_type& c2) noexcept;
    static constexpr bool eq(char_type c1, char_type c2) noexcept;
    static constexpr bool lt(char_type c1, char_type c2) noexcept;

    static int              compare(const char_type* s1, const char_type* s2, size_t n);
    static size_t           length(const char_type* s);
    static const char_type* find(const char_type* s, size_t n, const char_type& a);
    static char_type*       move(char_type* s1, const char_type* s2, size_t n);
    static char_type*       copy(char_type* s1, const char_type* s2, size_t n);
    static char_type*       assign(char_type* s, size_t n, char_type a);

    static constexpr int_type  not_eof(int_type c) noexcept;
    static constexpr char_type to_char_type(int_type c) noexcept;
    static constexpr int_type  to_int_type(char_type c) noexcept;
    static constexpr bool      eq_int_type(int_type c1, int_type c2) noexcept;
    static constexpr int_type  eof() noexcept;
};

template <> struct char_traits<char>;
template <> struct char_traits<wchar_t>;
template <> struct char_traits<char8_t>;  // C++20
template <> struct char_traits<char16_t>;
template <> struct char_traits<char32_t>;

template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
class basic_string
{
public:
// types:
    typedef traits traits_type;
    typedef typename traits_type::char_type value_type;
    typedef Allocator allocator_type;
    typedef typename allocator_type::size_type size_type;
    typedef typename allocator_type::difference_type difference_type;
    typedef typename allocator_type::reference reference;
    typedef typename allocator_type::const_reference const_reference;
    typedef typename allocator_type::pointer pointer;
    typedef typename allocator_type::const_pointer const_pointer;
    typedef implementation-defined iterator;
    typedef implementation-defined const_iterator;
    typedef std::reverse_iterator<iterator> reverse_iterator;
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

    static const size_type npos = -1;

    basic_string()
        noexcept(is_nothrow_default_constructible<allocator_type>::value);                      // constexpr since C++20
    explicit basic_string(const allocator_type& a);                                             // constexpr since C++20
    basic_string(const basic_string& str);                                                      // constexpr since C++20
    basic_string(basic_string&& str)
        noexcept(is_nothrow_move_constructible<allocator_type>::value);                         // constexpr since C++20
    basic_string(const basic_string& str, size_type pos,
                 const allocator_type& a = allocator_type());                                   // constexpr since C++20
    basic_string(const basic_string& str, size_type pos, size_type n,
                 const Allocator& a = Allocator());                                             // constexpr since C++20
    constexpr basic_string(
        basic_string&& str, size_type pos, const Allocator& a = Allocator());                   // since C++23
    constexpr basic_string(
        basic_string&& str, size_type pos, size_type n, const Allocator& a = Allocator());      // since C++23
    template<class T>
        basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator()); // C++17, constexpr since C++20
    template <class T>
        explicit basic_string(const T& t, const Allocator& a = Allocator());                    // C++17, constexpr since C++20
    basic_string(const value_type* s, const allocator_type& a = allocator_type());              // constexpr since C++20
    basic_string(const value_type* s, size_type n, const allocator_type& a = allocator_type()); // constexpr since C++20
    basic_string(nullptr_t) = delete; // C++23
    basic_string(size_type n, value_type c, const allocator_type& a = allocator_type());        // constexpr since C++20
    template<class InputIterator>
        basic_string(InputIterator begin, InputIterator end,
                     const allocator_type& a = allocator_type());                               // constexpr since C++20
    template<container-compatible-range<charT> R>
      constexpr basic_string(from_range_t, R&& rg, const Allocator& a = Allocator());           // since C++23
    basic_string(initializer_list<value_type>, const Allocator& = Allocator());                 // constexpr since C++20
    basic_string(const basic_string&, const Allocator&);                                        // constexpr since C++20
    basic_string(basic_string&&, const Allocator&);                                             // constexpr since C++20

    ~basic_string();                                                                            // constexpr since C++20

    operator basic_string_view<charT, traits>() const noexcept;                                 // constexpr since C++20

    basic_string& operator=(const basic_string& str);                                           // constexpr since C++20
    template <class T>
        basic_string& operator=(const T& t);                                                    // C++17, constexpr since C++20
    basic_string& operator=(basic_string&& str)
        noexcept(
             allocator_type::propagate_on_container_move_assignment::value ||
             allocator_type::is_always_equal::value );                                          // C++17, constexpr since C++20
    basic_string& operator=(const value_type* s);                                               // constexpr since C++20
    basic_string& operator=(nullptr_t) = delete; // C++23
    basic_string& operator=(value_type c);                                                      // constexpr since C++20
    basic_string& operator=(initializer_list<value_type>);                                      // constexpr since C++20

    iterator       begin() noexcept;                                                            // constexpr since C++20
    const_iterator begin() const noexcept;                                                      // constexpr since C++20
    iterator       end() noexcept;                                                              // constexpr since C++20
    const_iterator end() const noexcept;                                                        // constexpr since C++20

    reverse_iterator       rbegin() noexcept;                                                   // constexpr since C++20
    const_reverse_iterator rbegin() const noexcept;                                             // constexpr since C++20
    reverse_iterator       rend() noexcept;                                                     // constexpr since C++20
    const_reverse_iterator rend() const noexcept;                                               // constexpr since C++20

    const_iterator         cbegin() const noexcept;                                             // constexpr since C++20
    const_iterator         cend() const noexcept;                                               // constexpr since C++20
    const_reverse_iterator crbegin() const noexcept;                                            // constexpr since C++20
    const_reverse_iterator crend() const noexcept;                                              // constexpr since C++20

    size_type size() const noexcept;                                                            // constexpr since C++20
    size_type length() const noexcept;                                                          // constexpr since C++20
    size_type max_size() const noexcept;                                                        // constexpr since C++20
    size_type capacity() const noexcept;                                                        // constexpr since C++20

    void resize(size_type n, value_type c);                                                     // constexpr since C++20
    void resize(size_type n);                                                                   // constexpr since C++20

    template<class Operation>
    constexpr void resize_and_overwrite(size_type n, Operation op); // since C++23

    void reserve(size_type res_arg);                                                            // constexpr since C++20
    void reserve();                                                                             // deprecated in C++20, removed in C++26
    void shrink_to_fit();                                                                       // constexpr since C++20
    void clear() noexcept;                                                                      // constexpr since C++20
    bool empty() const noexcept;                                                                // constexpr since C++20

    const_reference operator[](size_type pos) const;                                            // constexpr since C++20
    reference       operator[](size_type pos);                                                  // constexpr since C++20

    const_reference at(size_type n) const;                                                      // constexpr since C++20
    reference       at(size_type n);                                                            // constexpr since C++20

    basic_string& operator+=(const basic_string& str);                                          // constexpr since C++20
    template <class T>
        basic_string& operator+=(const T& t);                                                   // C++17, constexpr since C++20
    basic_string& operator+=(const value_type* s);                                              // constexpr since C++20
    basic_string& operator+=(value_type c);                                                     // constexpr since C++20
    basic_string& operator+=(initializer_list<value_type>);                                     // constexpr since C++20

    basic_string& append(const basic_string& str);                                              // constexpr since C++20
    template <class T>
        basic_string& append(const T& t);                                                       // C++17, constexpr since C++20
    basic_string& append(const basic_string& str, size_type pos, size_type n=npos);             // C++14, constexpr since C++20
    template <class T>
        basic_string& append(const T& t, size_type pos, size_type n=npos);                      // C++17, constexpr since C++20
    basic_string& append(const value_type* s, size_type n);                                     // constexpr since C++20
    basic_string& append(const value_type* s);                                                  // constexpr since C++20
    basic_string& append(size_type n, value_type c);                                            // constexpr since C++20
    template<class InputIterator>
        basic_string& append(InputIterator first, InputIterator last);                          // constexpr since C++20
    template<container-compatible-range<charT> R>
      constexpr basic_string& append_range(R&& rg);                                             // C++23
    basic_string& append(initializer_list<value_type>);                                         // constexpr since C++20

    void push_back(value_type c);                                                               // constexpr since C++20
    void pop_back();                                                                            // constexpr since C++20
    reference       front();                                                                    // constexpr since C++20
    const_reference front() const;                                                              // constexpr since C++20
    reference       back();                                                                     // constexpr since C++20
    const_reference back() const;                                                               // constexpr since C++20

    basic_string& assign(const basic_string& str);                                              // constexpr since C++20
    template <class T>
        basic_string& assign(const T& t);                                                       // C++17, constexpr since C++20
    basic_string& assign(basic_string&& str);                                                   // constexpr since C++20
    basic_string& assign(const basic_string& str, size_type pos, size_type n=npos);             // C++14, constexpr since C++20
    template <class T>
        basic_string& assign(const T& t, size_type pos, size_type n=npos);                      // C++17, constexpr since C++20
    basic_string& assign(const value_type* s, size_type n);                                     // constexpr since C++20
    basic_string& assign(const value_type* s);                                                  // constexpr since C++20
    basic_string& assign(size_type n, value_type c);                                            // constexpr since C++20
    template<class InputIterator>
        basic_string& assign(InputIterator first, InputIterator last);                          // constexpr since C++20
    template<container-compatible-range<charT> R>
      constexpr basic_string& assign_range(R&& rg);                                             // C++23
    basic_string& assign(initializer_list<value_type>);                                         // constexpr since C++20

    basic_string& insert(size_type pos1, const basic_string& str);                              // constexpr since C++20
    template <class T>
        basic_string& insert(size_type pos1, const T& t);                                       // constexpr since C++20
    basic_string& insert(size_type pos1, const basic_string& str,
                         size_type pos2, size_type n);                                          // constexpr since C++20
    template <class T>
        basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n);          // C++17, constexpr since C++20
    basic_string& insert(size_type pos, const value_type* s, size_type n=npos);                 // C++14, constexpr since C++20
    basic_string& insert(size_type pos, const value_type* s);                                   // constexpr since C++20
    basic_string& insert(size_type pos, size_type n, value_type c);                             // constexpr since C++20
    iterator      insert(const_iterator p, value_type c);                                       // constexpr since C++20
    iterator      insert(const_iterator p, size_type n, value_type c);                          // constexpr since C++20
    template<class InputIterator>
        iterator insert(const_iterator p, InputIterator first, InputIterator last);             // constexpr since C++20
    template<container-compatible-range<charT> R>
      constexpr iterator insert_range(const_iterator p, R&& rg);                                // C++23
    iterator      insert(const_iterator p, initializer_list<value_type>);                       // constexpr since C++20

    basic_string& erase(size_type pos = 0, size_type n = npos);                                 // constexpr since C++20
    iterator      erase(const_iterator position);                                               // constexpr since C++20
    iterator      erase(const_iterator first, const_iterator last);                             // constexpr since C++20

    basic_string& replace(size_type pos1, size_type n1, const basic_string& str);               // constexpr since C++20
    template <class T>
    basic_string& replace(size_type pos1, size_type n1, const T& t);                            // C++17, constexpr since C++20
    basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
                          size_type pos2, size_type n2=npos);                                   // C++14, constexpr since C++20
    template <class T>
        basic_string& replace(size_type pos1, size_type n1, const T& t,
                              size_type pos2, size_type n);                                     // C++17, constexpr since C++20
    basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2);      // constexpr since C++20
    basic_string& replace(size_type pos, size_type n1, const value_type* s);                    // constexpr since C++20
    basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c);             // constexpr since C++20
    basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);       // constexpr since C++20
    template <class T>
        basic_string& replace(const_iterator i1, const_iterator i2, const T& t);                // C++17, constexpr since C++20
    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s, size_type n); // constexpr since C++20
    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s);           // constexpr since C++20
    basic_string& replace(const_iterator i1, const_iterator i2, size_type n, value_type c);     // constexpr since C++20
    template<class InputIterator>
        basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2); // constexpr since C++20
    template<container-compatible-range<charT> R>
      constexpr basic_string& replace_with_range(const_iterator i1, const_iterator i2, R&& rg); // C++23
    basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<value_type>);  // constexpr since C++20

    size_type copy(value_type* s, size_type n, size_type pos = 0) const;                        // constexpr since C++20
    basic_string substr(size_type pos = 0, size_type n = npos) const;                           // constexpr in C++20, removed in C++23
    basic_string substr(size_type pos = 0, size_type n = npos) const&;                          // since C++23
    constexpr basic_string substr(size_type pos = 0, size_type n = npos) &&;                    // since C++23
    void swap(basic_string& str)
        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
                 allocator_traits<allocator_type>::is_always_equal::value);                     // C++17, constexpr since C++20

    const value_type* c_str() const noexcept;                                                   // constexpr since C++20
    const value_type* data() const noexcept;                                                    // constexpr since C++20
          value_type* data()       noexcept;                                                    // C++17, constexpr since C++20

    allocator_type get_allocator() const noexcept;                                              // constexpr since C++20

    size_type find(const basic_string& str, size_type pos = 0) const noexcept;                  // constexpr since C++20
    template <class T>
        size_type find(const T& t, size_type pos = 0) const noexcept;                           // C++17, noexcept as an extension, constexpr since C++20
    size_type find(const value_type* s, size_type pos, size_type n) const noexcept;             // constexpr since C++20
    size_type find(const value_type* s, size_type pos = 0) const noexcept;                      // constexpr since C++20
    size_type find(value_type c, size_type pos = 0) const noexcept;                             // constexpr since C++20

    size_type rfind(const basic_string& str, size_type pos = npos) const noexcept;              // constexpr since C++20
    template <class T>
        size_type rfind(const T& t, size_type pos = npos) const noexcept;                       // C++17, noexcept as an extension, constexpr since C++20
    size_type rfind(const value_type* s, size_type pos, size_type n) const noexcept;            // constexpr since C++20
    size_type rfind(const value_type* s, size_type pos = npos) const noexcept;                  // constexpr since C++20
    size_type rfind(value_type c, size_type pos = npos) const noexcept;                         // constexpr since C++20

    size_type find_first_of(const basic_string& str, size_type pos = 0) const noexcept;         // constexpr since C++20
    template <class T>
        size_type find_first_of(const T& t, size_type pos = 0) const noexcept;                  // C++17, noexcept as an extension, constexpr since C++20
    size_type find_first_of(const value_type* s, size_type pos, size_type n) const noexcept;    // constexpr since C++20
    size_type find_first_of(const value_type* s, size_type pos = 0) const noexcept;             // constexpr since C++20
    size_type find_first_of(value_type c, size_type pos = 0) const noexcept;                    // constexpr since C++20

    size_type find_last_of(const basic_string& str, size_type pos = npos) const noexcept;       // constexpr since C++20
    template <class T>
        size_type find_last_of(const T& t, size_type pos = npos) const noexcept noexcept;       // C++17, noexcept as an extension, constexpr since C++20
    size_type find_last_of(const value_type* s, size_type pos, size_type n) const noexcept;     // constexpr since C++20
    size_type find_last_of(const value_type* s, size_type pos = npos) const noexcept;           // constexpr since C++20
    size_type find_last_of(value_type c, size_type pos = npos) const noexcept;                  // constexpr since C++20

    size_type find_first_not_of(const basic_string& str, size_type pos = 0) const noexcept;     // constexpr since C++20
    template <class T>
        size_type find_first_not_of(const T& t, size_type pos = 0) const noexcept;              // C++17, noexcept as an extension, constexpr since C++20
    size_type find_first_not_of(const value_type* s, size_type pos, size_type n) const noexcept; // constexpr since C++20
    size_type find_first_not_of(const value_type* s, size_type pos = 0) const noexcept;         // constexpr since C++20
    size_type find_first_not_of(value_type c, size_type pos = 0) const noexcept;                // constexpr since C++20

    size_type find_last_not_of(const basic_string& str, size_type pos = npos) const noexcept;   // constexpr since C++20
    template <class T>
        size_type find_last_not_of(const T& t, size_type pos = npos) const noexcept;            // C++17, noexcept as an extension, constexpr since C++20
    size_type find_last_not_of(const value_type* s, size_type pos, size_type n) const noexcept; // constexpr since C++20
    size_type find_last_not_of(const value_type* s, size_type pos = npos) const noexcept;       // constexpr since C++20
    size_type find_last_not_of(value_type c, size_type pos = npos) const noexcept;              // constexpr since C++20

    int compare(const basic_string& str) const noexcept;                                        // constexpr since C++20
    template <class T>
        int compare(const T& t) const noexcept;                                                 // C++17, noexcept as an extension, constexpr since C++20
    int compare(size_type pos1, size_type n1, const basic_string& str) const;                   // constexpr since C++20
    template <class T>
        int compare(size_type pos1, size_type n1, const T& t) const;                            // C++17, constexpr since C++20
    int compare(size_type pos1, size_type n1, const basic_string& str,
                size_type pos2, size_type n2=npos) const;                                       // C++14, constexpr since C++20
    template <class T>
        int compare(size_type pos1, size_type n1, const T& t,
                    size_type pos2, size_type n2=npos) const;                                   // C++17, constexpr since C++20
    int compare(const value_type* s) const noexcept;                                            // constexpr since C++20
    int compare(size_type pos1, size_type n1, const value_type* s) const;                       // constexpr since C++20
    int compare(size_type pos1, size_type n1, const value_type* s, size_type n2) const;         // constexpr since C++20

    constexpr bool starts_with(basic_string_view<charT, traits> sv) const noexcept;             // C++20
    constexpr bool starts_with(charT c) const noexcept;                                         // C++20
    constexpr bool starts_with(const charT* s) const;                                           // C++20
    constexpr bool ends_with(basic_string_view<charT, traits> sv) const noexcept;               // C++20
    constexpr bool ends_with(charT c) const noexcept;                                           // C++20
    constexpr bool ends_with(const charT* s) const;                                             // C++20

    constexpr bool contains(basic_string_view<charT, traits> sv) const noexcept;                // C++23
    constexpr bool contains(charT c) const noexcept;                                            // C++23
    constexpr bool contains(const charT* s) const;                                              // C++23
};

template<class InputIterator,
         class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
basic_string(InputIterator, InputIterator, Allocator = Allocator())
   -> basic_string<typename iterator_traits<InputIterator>::value_type,
                  char_traits<typename iterator_traits<InputIterator>::value_type>,
                  Allocator>;   // C++17

template<ranges::input_range R,
         class Allocator = allocator<ranges::range_value_t<R>>>
  basic_string(from_range_t, R&&, Allocator = Allocator())
    -> basic_string<ranges::range_value_t<R>, char_traits<ranges::range_value_t<R>>,
                    Allocator>; // C++23

template<class charT,
         class traits,
         class Allocator = allocator<charT>>
  explicit basic_string(basic_string_view<charT, traits>, const Allocator& = Allocator())
    -> basic_string<charT, traits, Allocator>; // C++17

template<class charT,
         class traits,
         class Allocator = allocator<charT>>
  basic_string(basic_string_view<charT, traits>,
                typename see below::size_type, typename see below::size_type,
                const Allocator& = Allocator())
    -> basic_string<charT, traits, Allocator>; // C++17

template<class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
operator+(const basic_string<charT, traits, Allocator>& lhs,
          const basic_string<charT, traits, Allocator>& rhs);                                   // constexpr since C++20

template<class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
operator+(const charT* lhs , const basic_string<charT,traits,Allocator>&rhs);                   // constexpr since C++20

template<class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);                          // constexpr since C++20

template<class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);                 // constexpr since C++20

template<class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);                        // constexpr since C++20

template<class charT, class traits, class Allocator>
bool operator==(const basic_string<charT, traits, Allocator>& lhs,
                const basic_string<charT, traits, Allocator>& rhs) noexcept;                    // constexpr since C++20

template<class charT, class traits, class Allocator>
bool operator==(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs) noexcept;    // constexpr since C++20

template<class charT, class traits, class Allocator>
bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
                const basic_string<charT, traits, Allocator>& rhs) noexcept;                    // removed in C++20

template<class charT, class traits, class Allocator>
bool operator!=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator!=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator< (const basic_string<charT, traits, Allocator>& lhs,
                const basic_string<charT, traits, Allocator>& rhs) noexcept;                    // removed in C++20

template<class charT, class traits, class Allocator>
bool operator< (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator< (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator> (const basic_string<charT, traits, Allocator>& lhs,
                const basic_string<charT, traits, Allocator>& rhs) noexcept;                    // removed in C++20

template<class charT, class traits, class Allocator>
bool operator> (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator> (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator<=(const basic_string<charT, traits, Allocator>& lhs,
                const basic_string<charT, traits, Allocator>& rhs) noexcept;                    // removed in C++20

template<class charT, class traits, class Allocator>
bool operator<=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator<=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator>=(const basic_string<charT, traits, Allocator>& lhs,
                const basic_string<charT, traits, Allocator>& rhs) noexcept;                    // removed in C++20

template<class charT, class traits, class Allocator>
bool operator>=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>
bool operator>=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;  // removed in C++20

template<class charT, class traits, class Allocator>                                            // since C++20
constexpr see below operator<=>(const basic_string<charT, traits, Allocator>& lhs,
                                const basic_string<charT, traits, Allocator>& rhs) noexcept;

template<class charT, class traits, class Allocator>                                            // since C++20
constexpr see below operator<=>(const basic_string<charT, traits, Allocator>& lhs,
                                const charT* rhs) noexcept;

template<class charT, class traits, class Allocator>
void swap(basic_string<charT, traits, Allocator>& lhs,
          basic_string<charT, traits, Allocator>& rhs)
            noexcept(noexcept(lhs.swap(rhs)));                                                  // constexpr since C++20

template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
operator>>(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);

template<class charT, class traits, class Allocator>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str);

template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str,
        charT delim);

template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);

template<class charT, class traits, class Allocator, class U>
typename basic_string<charT, traits, Allocator>::size_type
erase(basic_string<charT, traits, Allocator>& c, const U& value);    // C++20
template<class charT, class traits, class Allocator, class Predicate>
typename basic_string<charT, traits, Allocator>::size_type
erase_if(basic_string<charT, traits, Allocator>& c, Predicate pred); // C++20

typedef basic_string<char>    string;
typedef basic_string<wchar_t> wstring;
typedef basic_string<char8_t> u8string; // C++20
typedef basic_string<char16_t> u16string;
typedef basic_string<char32_t> u32string;

int                stoi  (const string& str, size_t* idx = nullptr, int base = 10);
long               stol  (const string& str, size_t* idx = nullptr, int base = 10);
unsigned long      stoul (const string& str, size_t* idx = nullptr, int base = 10);
long long          stoll (const string& str, size_t* idx = nullptr, int base = 10);
unsigned long long stoull(const string& str, size_t* idx = nullptr, int base = 10);

float       stof (const string& str, size_t* idx = nullptr);
double      stod (const string& str, size_t* idx = nullptr);
long double stold(const string& str, size_t* idx = nullptr);

string to_string(int val);
string to_string(unsigned val);
string to_string(long val);
string to_string(unsigned long val);
string to_string(long long val);
string to_string(unsigned long long val);
string to_string(float val);
string to_string(double val);
string to_string(long double val);

int                stoi  (const wstring& str, size_t* idx = nullptr, int base = 10);
long               stol  (const wstring& str, size_t* idx = nullptr, int base = 10);
unsigned long      stoul (const wstring& str, size_t* idx = nullptr, int base = 10);
long long          stoll (const wstring& str, size_t* idx = nullptr, int base = 10);
unsigned long long stoull(const wstring& str, size_t* idx = nullptr, int base = 10);

float       stof (const wstring& str, size_t* idx = nullptr);
double      stod (const wstring& str, size_t* idx = nullptr);
long double stold(const wstring& str, size_t* idx = nullptr);

wstring to_wstring(int val);
wstring to_wstring(unsigned val);
wstring to_wstring(long val);
wstring to_wstring(unsigned long val);
wstring to_wstring(long long val);
wstring to_wstring(unsigned long long val);
wstring to_wstring(float val);
wstring to_wstring(double val);
wstring to_wstring(long double val);

template <> struct hash<string>;
template <> struct hash<u8string>; // C++20
template <> struct hash<u16string>;
template <> struct hash<u32string>;
template <> struct hash<wstring>;

basic_string<char>     operator""s( const char *str,     size_t len );           // C++14, constexpr since C++20
basic_string<wchar_t>  operator""s( const wchar_t *str,  size_t len );           // C++14, constexpr since C++20
constexpr basic_string<char8_t>  operator""s( const char8_t *str,  size_t len ); // C++20
basic_string<char16_t> operator""s( const char16_t *str, size_t len );           // C++14, constexpr since C++20
basic_string<char32_t> operator""s( const char32_t *str, size_t len );           // C++14, constexpr since C++20

}  // std

*/

// clang-format on

#include <__algorithm/max.h>
#include <__algorithm/min.h>
#include <__algorithm/remove.h>
#include <__algorithm/remove_if.h>
#include <__assert> // all public C++ headers provide the assertion handler
#include <__config>
#include <__format/enable_insertable.h>
#include <__functional/hash.h>
#include <__functional/unary_function.h>
#include <__fwd/string.h>
#include <__ios/fpos.h>
#include <__iterator/distance.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/reverse_iterator.h>
#include <__iterator/wrap_iter.h>
#include <__memory/addressof.h>
#include <__memory/allocate_at_least.h>
#include <__memory/allocator.h>
#include <__memory/allocator_traits.h>
#include <__memory/compressed_pair.h>
#include <__memory/construct_at.h>
#include <__memory/pointer_traits.h>
#include <__memory/swap_allocator.h>
#include <__memory_resource/polymorphic_allocator.h>
#include <__ranges/access.h>
#include <__ranges/concepts.h>
#include <__ranges/container_compatible_range.h>
#include <__ranges/from_range.h>
#include <__ranges/size.h>
#include <__string/char_traits.h>
#include <__string/extern_template_lists.h>
#include <__type_traits/is_allocator.h>
#include <__type_traits/is_array.h>
#include <__type_traits/is_convertible.h>
#include <__type_traits/is_nothrow_default_constructible.h>
#include <__type_traits/is_nothrow_move_assignable.h>
#include <__type_traits/is_same.h>
#include <__type_traits/is_standard_layout.h>
#include <__type_traits/is_trivial.h>
#include <__type_traits/noexcept_move_assign_container.h>
#include <__type_traits/remove_cvref.h>
#include <__type_traits/void_t.h>
#include <__utility/auto_cast.h>
#include <__utility/declval.h>
#include <__utility/forward.h>
#include <__utility/is_pointer_in_range.h>
#include <__utility/move.h>
#include <__utility/swap.h>
#include <__utility/unreachable.h>
#include <climits>
#include <cstdio> // EOF
#include <cstring>
#include <limits>
#include <stdexcept>
#include <string_view>
#include <version>

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
#  include <cwchar>
#endif

// standard-mandated includes

// [iterator.range]
#include <__iterator/access.h>
#include <__iterator/data.h>
#include <__iterator/empty.h>
#include <__iterator/reverse_access.h>
#include <__iterator/size.h>

// [string.syn]
#include <compare>
#include <initializer_list>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

#if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
#  define _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS __attribute__((__no_sanitize__("address")))
// This macro disables AddressSanitizer (ASan) instrumentation for a specific function,
// allowing memory accesses that would normally trigger ASan errors to proceed without crashing.
// This is useful for accessing parts of objects memory, which should not be accessed,
// such as unused bytes in short strings, that should never be accessed
// by other parts of the program.
#else
#  define _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS
#endif
#define _LIBCPP_SHORT_STRING_ANNOTATIONS_ALLOWED false

_LIBCPP_BEGIN_NAMESPACE_STD

// basic_string

template <class _CharT, class _Traits, class _Allocator>
basic_string<_CharT, _Traits, _Allocator> _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, const basic_string<_CharT, _Traits, _Allocator>& __y);

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDDEN _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const _CharT* __x, const basic_string<_CharT, _Traits, _Allocator>& __y);

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(_CharT __x, const basic_string<_CharT, _Traits, _Allocator>& __y);

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, const _CharT* __y);

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, _CharT __y);

extern template _LIBCPP_EXPORTED_FROM_ABI string operator+
    <char, char_traits<char>, allocator<char> >(char const*, string const&);

template <class _Iter>
struct __string_is_trivial_iterator : public false_type {};

template <class _Tp>
struct __string_is_trivial_iterator<_Tp*> : public is_arithmetic<_Tp> {};

template <class _Iter>
struct __string_is_trivial_iterator<__wrap_iter<_Iter> > : public __string_is_trivial_iterator<_Iter> {};

template <class _CharT, class _Traits, class _Tp>
struct __can_be_converted_to_string_view
    : public _BoolConstant< is_convertible<const _Tp&, basic_string_view<_CharT, _Traits> >::value &&
                            !is_convertible<const _Tp&, const _CharT*>::value > {};

struct __uninitialized_size_tag {};
struct __init_with_sentinel_tag {};

template <class _CharT, class _Traits, class _Allocator>
class basic_string {
private:
  using __default_allocator_type = allocator<_CharT>;

public:
  typedef basic_string __self;
  typedef basic_string_view<_CharT, _Traits> __self_view;
  typedef _Traits traits_type;
  typedef _CharT value_type;
  typedef _Allocator allocator_type;
  typedef allocator_traits<allocator_type> __alloc_traits;
  typedef typename __alloc_traits::size_type size_type;
  typedef typename __alloc_traits::difference_type difference_type;
  typedef value_type& reference;
  typedef const value_type& const_reference;
  typedef typename __alloc_traits::pointer pointer;
  typedef typename __alloc_traits::const_pointer const_pointer;

  static_assert((!is_array<value_type>::value), "Character type of basic_string must not be an array");
  static_assert((is_standard_layout<value_type>::value), "Character type of basic_string must be standard-layout");
  static_assert((is_trivial<value_type>::value), "Character type of basic_string must be trivial");
  static_assert((is_same<_CharT, typename traits_type::char_type>::value),
                "traits_type::char_type must be the same type as CharT");
  static_assert((is_same<typename allocator_type::value_type, value_type>::value),
                "Allocator::value_type must be same type as value_type");

  static_assert(is_same<allocator_type, __rebind_alloc<__alloc_traits, value_type> >::value,
                "[allocator.requirements] states that rebinding an allocator to the same type should result in the "
                "original allocator");

  // TODO: Implement iterator bounds checking without requiring the global database.
  typedef __wrap_iter<pointer> iterator;
  typedef __wrap_iter<const_pointer> const_iterator;
  typedef std::reverse_iterator<iterator> reverse_iterator;
  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

private:
  static_assert(CHAR_BIT == 8, "This implementation assumes that one byte contains 8 bits");

#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT

  struct __long {
    pointer __data_;
    size_type __size_;
    size_type __cap_ : sizeof(size_type) * CHAR_BIT - 1;
    size_type __is_long_ : 1;
  };

  enum { __min_cap = (sizeof(__long) - 1) / sizeof(value_type) > 2 ? (sizeof(__long) - 1) / sizeof(value_type) : 2 };

  struct __short {
    value_type __data_[__min_cap];
    unsigned char __padding_[sizeof(value_type) - 1];
    unsigned char __size_    : 7;
    unsigned char __is_long_ : 1;
  };

  // The __endian_factor is required because the field we use to store the size
  // has one fewer bit than it would if it were not a bitfield.
  //
  // If the LSB is used to store the short-flag in the short string representation,
  // we have to multiply the size by two when it is stored and divide it by two when
  // it is loaded to make sure that we always store an even number. In the long string
  // representation, we can ignore this because we can assume that we always allocate
  // an even amount of value_types.
  //
  // If the MSB is used for the short-flag, the max_size() is numeric_limits<size_type>::max() / 2.
  // This does not impact the short string representation, since we never need the MSB
  // for representing the size of a short string anyway.

#  ifdef _LIBCPP_BIG_ENDIAN
  static const size_type __endian_factor = 2;
#  else
  static const size_type __endian_factor = 1;
#  endif

#else // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT

#  ifdef _LIBCPP_BIG_ENDIAN
  static const size_type __endian_factor = 1;
#  else
  static const size_type __endian_factor = 2;
#  endif

  // Attribute 'packed' is used to keep the layout compatible with the
  // previous definition that did not use bit fields. This is because on
  // some platforms bit fields have a default size rather than the actual
  // size used, e.g., it is 4 bytes on AIX. See D128285 for details.
  struct __long {
    struct _LIBCPP_PACKED {
      size_type __is_long_ : 1;
      size_type __cap_ : sizeof(size_type) * CHAR_BIT - 1;
    };
    size_type __size_;
    pointer __data_;
  };

  enum { __min_cap = (sizeof(__long) - 1) / sizeof(value_type) > 2 ? (sizeof(__long) - 1) / sizeof(value_type) : 2 };

  struct __short {
    struct _LIBCPP_PACKED {
      unsigned char __is_long_ : 1;
      unsigned char __size_    : 7;
    };
    char __padding_[sizeof(value_type) - 1];
    value_type __data_[__min_cap];
  };

#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT

  static_assert(sizeof(__short) == (sizeof(value_type) * (__min_cap + 1)), "__short has an unexpected size.");

  union __ulx {
    __long __lx;
    __short __lxx;
  };

  enum { __n_words = sizeof(__ulx) / sizeof(size_type) };

  struct __raw {
    size_type __words[__n_words];
  };

  struct __rep {
    union {
      __short __s;
      __long __l;
      __raw __r;
    };
  };

  __compressed_pair<__rep, allocator_type> __r_;

  // Construct a string with the given allocator and enough storage to hold `__size` characters, but
  // don't initialize the characters. The contents of the string, including the null terminator, must be
  // initialized separately.
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit basic_string(
      __uninitialized_size_tag, size_type __size, const allocator_type& __a)
      : __r_(__default_init_tag(), __a) {
    if (__size > max_size())
      __throw_length_error();
    if (__fits_in_sso(__size)) {
      __r_.first() = __rep();
      __set_short_size(__size);
    } else {
      auto __capacity   = __recommend(__size) + 1;
      auto __allocation = __alloc_traits::allocate(__alloc(), __capacity);
      __begin_lifetime(__allocation, __capacity);
      __set_long_cap(__capacity);
      __set_long_pointer(__allocation);
      __set_long_size(__size);
    }
    __annotate_new(__size);
  }

  template <class _Iter, class _Sent>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  basic_string(__init_with_sentinel_tag, _Iter __first, _Sent __last, const allocator_type& __a)
      : __r_(__default_init_tag(), __a) {
    __init_with_sentinel(std::move(__first), std::move(__last));
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator __make_iterator(pointer __p) { return iterator(__p); }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_iterator __make_const_iterator(const_pointer __p) const {
    return const_iterator(__p);
  }

public:
  _LIBCPP_TEMPLATE_DATA_VIS static const size_type npos = -1;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string()
      _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
      : __r_(__value_init_tag(), __default_init_tag()) {
    __annotate_new(0);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit basic_string(const allocator_type& __a)
#if _LIBCPP_STD_VER <= 14
      _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
#else
      _NOEXCEPT
#endif
      : __r_(__value_init_tag(), __a) {
    __annotate_new(0);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS basic_string(const basic_string& __str)
      : __r_(__default_init_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc())) {
    if (!__str.__is_long()) {
      __r_.first() = __str.__r_.first();
      __annotate_new(__get_short_size());
    } else
      __init_copy_ctor_external(std::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS
  basic_string(const basic_string& __str, const allocator_type& __a)
      : __r_(__default_init_tag(), __a) {
    if (!__str.__is_long()) {
      __r_.first() = __str.__r_.first();
      __annotate_new(__get_short_size());
    } else
      __init_copy_ctor_external(std::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
  }

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(basic_string&& __str)
#  if _LIBCPP_STD_VER <= 14
      _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
#  else
      _NOEXCEPT
#  endif
      // Turning off ASan instrumentation for variable initialization with _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS
      // does not work consistently during initialization of __r_, so we instead unpoison __str's memory manually first.
      // __str's memory needs to be unpoisoned only in the case where it's a short string.
      : __r_([](basic_string &__s) -> decltype(__s.__r_)&& { if(!__s.__is_long()) __s.__annotate_delete(); return std::move(__s.__r_); }(__str)) {
    __str.__r_.first() = __rep();
    __str.__annotate_new(0);
    if (!__is_long())
      __annotate_new(size());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(basic_string&& __str, const allocator_type& __a)
      : __r_(__default_init_tag(), __a) {
    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
      __init(std::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
    else {
      if (__libcpp_is_constant_evaluated())
        __r_.first() = __rep();
      if (!__str.__is_long())
        __str.__annotate_delete();
      __r_.first()       = __str.__r_.first();
      __str.__r_.first() = __rep();
      __str.__annotate_new(0);
      if (!__is_long() && this != &__str)
        __annotate_new(size());
    }
  }
#endif // _LIBCPP_CXX03_LANG

  template <__enable_if_t<__is_allocator<_Allocator>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(const _CharT* __s)
      : __r_(__default_init_tag(), __default_init_tag()) {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "basic_string(const char*) detected nullptr");
    __init(__s, traits_type::length(__s));
  }

  template <__enable_if_t<__is_allocator<_Allocator>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(const _CharT* __s, const _Allocator& __a)
      : __r_(__default_init_tag(), __a) {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
    __init(__s, traits_type::length(__s));
  }

#if _LIBCPP_STD_VER >= 23
  basic_string(nullptr_t) = delete;
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(const _CharT* __s, size_type __n)
      : __r_(__default_init_tag(), __default_init_tag()) {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
    __init(__s, __n);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
      : __r_(__default_init_tag(), __a) {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
    __init(__s, __n);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(size_type __n, _CharT __c)
      : __r_(__default_init_tag(), __default_init_tag()) {
    __init(__n, __c);
  }

#if _LIBCPP_STD_VER >= 23
  _LIBCPP_HIDE_FROM_ABI constexpr basic_string(
      basic_string&& __str, size_type __pos, const _Allocator& __alloc = _Allocator())
      : basic_string(std::move(__str), __pos, npos, __alloc) {}

  _LIBCPP_HIDE_FROM_ABI constexpr basic_string(
      basic_string&& __str, size_type __pos, size_type __n, const _Allocator& __alloc = _Allocator())
      : __r_(__default_init_tag(), __alloc) {
    if (__pos > __str.size())
      __throw_out_of_range();

    auto __len = std::min<size_type>(__n, __str.size() - __pos);
    if (__alloc_traits::is_always_equal::value || __alloc == __str.__alloc()) {
      __move_assign(std::move(__str), __pos, __len);
    } else {
      // Perform a copy because the allocators are not compatible.
      __init(__str.data() + __pos, __len);
    }
  }
#endif

  template <__enable_if_t<__is_allocator<_Allocator>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(size_type __n, _CharT __c, const _Allocator& __a)
      : __r_(__default_init_tag(), __a) {
    __init(__n, __c);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20
  basic_string(const basic_string& __str, size_type __pos, size_type __n, const _Allocator& __a = _Allocator())
      : __r_(__default_init_tag(), __a) {
    size_type __str_sz = __str.size();
    if (__pos > __str_sz)
      __throw_out_of_range();
    __init(__str.data() + __pos, std::min(__n, __str_sz - __pos));
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  basic_string(const basic_string& __str, size_type __pos, const _Allocator& __a = _Allocator())
      : __r_(__default_init_tag(), __a) {
    size_type __str_sz = __str.size();
    if (__pos > __str_sz)
      __throw_out_of_range();
    __init(__str.data() + __pos, __str_sz - __pos);
  }

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20
  basic_string(const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a = allocator_type())
      : __r_(__default_init_tag(), __a) {
    __self_view __sv0 = __t;
    __self_view __sv  = __sv0.substr(__pos, __n);
    __init(__sv.data(), __sv.size());
  }

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit basic_string(const _Tp& __t)
      : __r_(__default_init_tag(), __default_init_tag()) {
    __self_view __sv = __t;
    __init(__sv.data(), __sv.size());
  }

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit basic_string(
      const _Tp& __t, const allocator_type& __a)
      : __r_(__default_init_tag(), __a) {
    __self_view __sv = __t;
    __init(__sv.data(), __sv.size());
  }

  template <class _InputIterator, __enable_if_t<__has_input_iterator_category<_InputIterator>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(_InputIterator __first, _InputIterator __last)
      : __r_(__default_init_tag(), __default_init_tag()) {
    __init(__first, __last);
  }

  template <class _InputIterator, __enable_if_t<__has_input_iterator_category<_InputIterator>::value, int> = 0>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  basic_string(_InputIterator __first, _InputIterator __last, const allocator_type& __a)
      : __r_(__default_init_tag(), __a) {
    __init(__first, __last);
  }

#if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<_CharT> _Range>
  _LIBCPP_HIDE_FROM_ABI constexpr basic_string(
      from_range_t, _Range&& __range, const allocator_type& __a = allocator_type())
      : __r_(__default_init_tag(), __a) {
    if constexpr (ranges::forward_range<_Range> || ranges::sized_range<_Range>) {
      __init_with_size(ranges::begin(__range), ranges::end(__range), ranges::distance(__range));
    } else {
      __init_with_sentinel(ranges::begin(__range), ranges::end(__range));
    }
  }
#endif

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(initializer_list<_CharT> __il)
      : __r_(__default_init_tag(), __default_init_tag()) {
    __init(__il.begin(), __il.end());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string(initializer_list<_CharT> __il, const _Allocator& __a)
      : __r_(__default_init_tag(), __a) {
    __init(__il.begin(), __il.end());
  }
#endif // _LIBCPP_CXX03_LANG

  inline _LIBCPP_CONSTEXPR_SINCE_CXX20 ~basic_string() {
    __annotate_delete();
    if (__is_long())
      __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 operator __self_view() const _NOEXCEPT {
    return __self_view(data(), size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS basic_string&
  operator=(const basic_string& __str);

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator=(const _Tp& __t) {
    __self_view __sv = __t;
    return assign(__sv);
  }

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator=(basic_string&& __str)
      _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value)) {
    __move_assign(__str, integral_constant<bool, __alloc_traits::propagate_on_container_move_assignment::value>());
    return *this;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator=(initializer_list<value_type> __il) {
    return assign(__il.begin(), __il.size());
  }
#endif
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator=(const value_type* __s) {
    return assign(__s);
  }
#if _LIBCPP_STD_VER >= 23
  basic_string& operator=(nullptr_t) = delete;
#endif
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS basic_string& operator=(value_type __c);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator begin() _NOEXCEPT {
    return __make_iterator(__get_pointer());
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_iterator begin() const _NOEXCEPT {
    return __make_const_iterator(__get_pointer());
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator end() _NOEXCEPT {
    return __make_iterator(__get_pointer() + size());
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_iterator end() const _NOEXCEPT {
    return __make_const_iterator(__get_pointer() + size());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reverse_iterator rbegin() _NOEXCEPT {
    return reverse_iterator(end());
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reverse_iterator rbegin() const _NOEXCEPT {
    return const_reverse_iterator(end());
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reverse_iterator rend() _NOEXCEPT {
    return reverse_iterator(begin());
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reverse_iterator rend() const _NOEXCEPT {
    return const_reverse_iterator(begin());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_iterator cbegin() const _NOEXCEPT { return begin(); }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_iterator cend() const _NOEXCEPT { return end(); }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reverse_iterator crbegin() const _NOEXCEPT {
    return rbegin();
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reverse_iterator crend() const _NOEXCEPT { return rend(); }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type size() const _NOEXCEPT {
    return __is_long() ? __get_long_size() : __get_short_size();
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type length() const _NOEXCEPT { return size(); }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type max_size() const _NOEXCEPT {
    size_type __m = __alloc_traits::max_size(__alloc());
    if (__m <= std::numeric_limits<size_type>::max() / 2) {
      return __m - __alignment;
    } else {
      bool __uses_lsb = __endian_factor == 2;
      return __uses_lsb ? __m - __alignment : (__m / 2) - __alignment;
    }
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type capacity() const _NOEXCEPT {
    return (__is_long() ? __get_long_cap() : static_cast<size_type>(__min_cap)) - 1;
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 void resize(size_type __n, value_type __c);
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void resize(size_type __n) { resize(__n, value_type()); }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 void reserve(size_type __requested_capacity);

#if _LIBCPP_STD_VER >= 23
  template <class _Op>
  _LIBCPP_HIDE_FROM_ABI constexpr void resize_and_overwrite(size_type __n, _Op __op) {
    __resize_default_init(__n);
    __erase_to_end(std::move(__op)(data(), _LIBCPP_AUTO_CAST(__n)));
  }
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __resize_default_init(size_type __n);

#if _LIBCPP_STD_VER < 26 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_STRING_RESERVE)
  _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void reserve() _NOEXCEPT { shrink_to_fit(); }
#endif
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void shrink_to_fit() _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void clear() _NOEXCEPT;

  _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool empty() const _NOEXCEPT {
    return size() == 0;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reference operator[](size_type __pos) const _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__pos <= size(), "string index out of bounds");
    if (__builtin_constant_p(__pos) && !__fits_in_sso(__pos)) {
      return *(__get_long_pointer() + __pos);
    }
    return *(data() + __pos);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference operator[](size_type __pos) _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__pos <= size(), "string index out of bounds");
    if (__builtin_constant_p(__pos) && !__fits_in_sso(__pos)) {
      return *(__get_long_pointer() + __pos);
    }
    return *(__get_pointer() + __pos);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reference at(size_type __n) const;
  _LIBCPP_CONSTEXPR_SINCE_CXX20 reference at(size_type __n);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator+=(const basic_string& __str) {
    return append(__str);
  }

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string >::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  operator+=(const _Tp& __t) {
    __self_view __sv = __t;
    return append(__sv);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator+=(const value_type* __s) {
    return append(__s);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator+=(value_type __c) {
    push_back(__c);
    return *this;
  }

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& operator+=(initializer_list<value_type> __il) {
    return append(__il);
  }
#endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const basic_string& __str) {
    return append(__str.data(), __str.size());
  }

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  append(const _Tp& __t) {
    __self_view __sv = __t;
    return append(__sv.data(), __sv.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const basic_string& __str, size_type __pos, size_type __n = npos);

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20

      basic_string&
      append(const _Tp& __t, size_type __pos, size_type __n = npos);

  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const value_type* __s, size_type __n);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(const value_type* __s);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(size_type __n, value_type __c);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __append_default_init(size_type __n);

  template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  append(_InputIterator __first, _InputIterator __last) {
    const basic_string __temp(__first, __last, __alloc());
    append(__temp.data(), __temp.size());
    return *this;
  }

  template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  append(_ForwardIterator __first, _ForwardIterator __last);

#if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<_CharT> _Range>
  _LIBCPP_HIDE_FROM_ABI constexpr basic_string& append_range(_Range&& __range) {
    insert_range(end(), std::forward<_Range>(__range));
    return *this;
  }
#endif

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& append(initializer_list<value_type> __il) {
    return append(__il.begin(), __il.size());
  }
#endif // _LIBCPP_CXX03_LANG

  _LIBCPP_CONSTEXPR_SINCE_CXX20 void push_back(value_type __c);
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void pop_back();

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference front() _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string::front(): string is empty");
    return *__get_pointer();
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reference front() const _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string::front(): string is empty");
    return *data();
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 reference back() _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string::back(): string is empty");
    return *(__get_pointer() + size() - 1);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_reference back() const _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string::back(): string is empty");
    return *(data() + size() - 1);
  }

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  assign(const _Tp& __t) {
    __self_view __sv = __t;
    return assign(__sv.data(), __sv.size());
  }

#if _LIBCPP_STD_VER >= 20
  _LIBCPP_HIDE_FROM_ABI constexpr void __move_assign(basic_string&& __str, size_type __pos, size_type __len) {
    // Pilfer the allocation from __str.
    _LIBCPP_ASSERT_INTERNAL(__alloc() == __str.__alloc(), "__move_assign called with wrong allocator");
    size_type __old_sz = __str.size();
    if (!__str.__is_long())
      __str.__annotate_delete();
    __r_.first()       = __str.__r_.first();
    __str.__r_.first() = __rep();
    __str.__annotate_new(0);

    _Traits::move(data(), data() + __pos, __len);
    __set_size(__len);
    _Traits::assign(data()[__len], value_type());

    if (!__is_long()) {
      __annotate_new(__len);
    } else if (__old_sz > __len) {
      __annotate_shrink(__old_sz);
    }
  }
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const basic_string& __str) {
    return *this = __str;
  }
#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(basic_string&& __str)
      _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value)) {
    *this = std::move(__str);
    return *this;
  }
#endif
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const basic_string& __str, size_type __pos, size_type __n = npos);

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  assign(const _Tp& __t, size_type __pos, size_type __n = npos);

  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const value_type* __s, size_type __n);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(const value_type* __s);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(size_type __n, value_type __c);
  template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  assign(_InputIterator __first, _InputIterator __last);

  template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  assign(_ForwardIterator __first, _ForwardIterator __last);

#if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<_CharT> _Range>
  _LIBCPP_HIDE_FROM_ABI constexpr basic_string& assign_range(_Range&& __range) {
    if constexpr (__string_is_trivial_iterator<ranges::iterator_t<_Range>>::value &&
                  (ranges::forward_range<_Range> || ranges::sized_range<_Range>)) {
      size_type __n = static_cast<size_type>(ranges::distance(__range));
      __assign_trivial(ranges::begin(__range), ranges::end(__range), __n);

    } else {
      __assign_with_sentinel(ranges::begin(__range), ranges::end(__range));
    }

    return *this;
  }
#endif

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& assign(initializer_list<value_type> __il) {
    return assign(__il.begin(), __il.size());
  }
#endif // _LIBCPP_CXX03_LANG

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  insert(size_type __pos1, const basic_string& __str) {
    return insert(__pos1, __str.data(), __str.size());
  }

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  insert(size_type __pos1, const _Tp& __t) {
    __self_view __sv = __t;
    return insert(__pos1, __sv.data(), __sv.size());
  }

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n = npos);

  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n = npos);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& insert(size_type __pos, const value_type* __s);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& insert(size_type __pos, size_type __n, value_type __c);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator insert(const_iterator __pos, value_type __c);

#if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<_CharT> _Range>
  _LIBCPP_HIDE_FROM_ABI constexpr iterator insert_range(const_iterator __position, _Range&& __range) {
    if constexpr (ranges::forward_range<_Range> || ranges::sized_range<_Range>) {
      auto __n = static_cast<size_type>(ranges::distance(__range));
      return __insert_with_size(__position, ranges::begin(__range), ranges::end(__range), __n);

    } else {
      basic_string __temp(from_range, std::forward<_Range>(__range), __alloc());
      return insert(__position, __temp.data(), __temp.data() + __temp.size());
    }
  }
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator
  insert(const_iterator __pos, size_type __n, value_type __c) {
    difference_type __p = __pos - begin();
    insert(static_cast<size_type>(__p), __n, __c);
    return begin() + __p;
  }

  template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator
  insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);

  template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator
  insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator
  insert(const_iterator __pos, initializer_list<value_type> __il) {
    return insert(__pos, __il.begin(), __il.end());
  }
#endif // _LIBCPP_CXX03_LANG

  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& erase(size_type __pos = 0, size_type __n = npos);
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator erase(const_iterator __pos);
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator erase(const_iterator __first, const_iterator __last);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(size_type __pos1, size_type __n1, const basic_string& __str) {
    return replace(__pos1, __n1, __str.data(), __str.size());
  }

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(size_type __pos1, size_type __n1, const _Tp& __t) {
    __self_view __sv = __t;
    return replace(__pos1, __n1, __sv.data(), __sv.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2 = npos);

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2 = npos);

  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(const_iterator __i1, const_iterator __i2, const basic_string& __str) {
    return replace(
        static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __str.data(), __str.size());
  }

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(const_iterator __i1, const_iterator __i2, const _Tp& __t) {
    __self_view __sv = __t;
    return replace(__i1 - begin(), __i2 - __i1, __sv);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n) {
    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s, __n);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(const_iterator __i1, const_iterator __i2, const value_type* __s) {
    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c) {
    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __n, __c);
  }

  template <class _InputIterator, __enable_if_t<__has_input_iterator_category<_InputIterator>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2);

#if _LIBCPP_STD_VER >= 23
  template <_ContainerCompatibleRange<_CharT> _Range>
  _LIBCPP_HIDE_FROM_ABI constexpr basic_string&
  replace_with_range(const_iterator __i1, const_iterator __i2, _Range&& __range) {
    basic_string __temp(from_range, std::forward<_Range>(__range), __alloc());
    return replace(__i1, __i2, __temp);
  }
#endif

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  replace(const_iterator __i1, const_iterator __i2, initializer_list<value_type> __il) {
    return replace(__i1, __i2, __il.begin(), __il.end());
  }
#endif // _LIBCPP_CXX03_LANG

  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type copy(value_type* __s, size_type __n, size_type __pos = 0) const;

#if _LIBCPP_STD_VER <= 20
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string
  substr(size_type __pos = 0, size_type __n = npos) const {
    return basic_string(*this, __pos, __n);
  }
#else
  _LIBCPP_HIDE_FROM_ABI constexpr basic_string substr(size_type __pos = 0, size_type __n = npos) const& {
    return basic_string(*this, __pos, __n);
  }

  _LIBCPP_HIDE_FROM_ABI constexpr basic_string substr(size_type __pos = 0, size_type __n = npos) && {
    return basic_string(std::move(*this), __pos, __n);
  }
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(basic_string& __str)
#if _LIBCPP_STD_VER >= 14
      _NOEXCEPT;
#else
      _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || __is_nothrow_swappable<allocator_type>::value);
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const value_type* c_str() const _NOEXCEPT { return data(); }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const value_type* data() const _NOEXCEPT {
    return std::__to_address(__get_pointer());
  }
#if _LIBCPP_STD_VER >= 17
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 value_type* data() _NOEXCEPT {
    return std::__to_address(__get_pointer());
  }
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator_type get_allocator() const _NOEXCEPT {
    return __alloc();
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;

  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type find(value_type __c, size_type __pos = 0) const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  rfind(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  rfind(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;

  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  rfind(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type rfind(value_type __c, size_type __pos = npos) const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_of(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;

  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;

  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_not_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_not_of(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;

  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_not_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_first_not_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_not_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_not_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;

  _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_not_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  find_last_not_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 int compare(const basic_string& __str) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 int
  compare(const _Tp& __t) const _NOEXCEPT;

  template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> = 0>
  _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS _LIBCPP_CONSTEXPR_SINCE_CXX20 int
  compare(size_type __pos1, size_type __n1, const _Tp& __t) const;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 int
  compare(size_type __pos1, size_type __n1, const basic_string& __str) const;
  _LIBCPP_CONSTEXPR_SINCE_CXX20 int
  compare(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2 = npos) const;

  template <class _Tp,
            __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                              !__is_same_uncvref<_Tp, basic_string>::value,
                          int> = 0>
  inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 int
  compare(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2 = npos) const;

  _LIBCPP_CONSTEXPR_SINCE_CXX20 int compare(const value_type* __s) const _NOEXCEPT;
  _LIBCPP_CONSTEXPR_SINCE_CXX20 int compare(size_type __pos1, size_type __n1, const value_type* __s) const;
  _LIBCPP_CONSTEXPR_SINCE_CXX20 int
  compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;

#if _LIBCPP_STD_VER >= 20
  constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(__self_view __sv) const noexcept {
    return __self_view(data(), size()).starts_with(__sv);
  }

  constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(value_type __c) const noexcept {
    return !empty() && _Traits::eq(front(), __c);
  }

  constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(const value_type* __s) const noexcept {
    return starts_with(__self_view(__s));
  }

  constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(__self_view __sv) const noexcept {
    return __self_view(data(), size()).ends_with(__sv);
  }

  constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(value_type __c) const noexcept {
    return !empty() && _Traits::eq(back(), __c);
  }

  constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(const value_type* __s) const noexcept {
    return ends_with(__self_view(__s));
  }
#endif

#if _LIBCPP_STD_VER >= 23
  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(__self_view __sv) const noexcept {
    return __self_view(data(), size()).contains(__sv);
  }

  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(value_type __c) const noexcept {
    return __self_view(data(), size()).contains(__c);
  }

  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(const value_type* __s) const {
    return __self_view(data(), size()).contains(__s);
  }
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __invariants() const;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __clear_and_shrink() _NOEXCEPT;

private:
  template <class _Alloc>
  inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool friend
  operator==(const basic_string<char, char_traits<char>, _Alloc>& __lhs,
             const basic_string<char, char_traits<char>, _Alloc>& __rhs) _NOEXCEPT;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __shrink_or_extend(size_type __target_capacity);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS bool
  __is_long() const _NOEXCEPT {
    if (__libcpp_is_constant_evaluated() && __builtin_constant_p(__r_.first().__l.__is_long_)) {
      return __r_.first().__l.__is_long_;
    }
    return __r_.first().__s.__is_long_;
  }

  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __begin_lifetime(pointer __begin, size_type __n) {
#if _LIBCPP_STD_VER >= 20
    if (__libcpp_is_constant_evaluated()) {
      for (size_type __i = 0; __i != __n; ++__i)
        std::construct_at(std::addressof(__begin[__i]));
    }
#else
    (void)__begin;
    (void)__n;
#endif // _LIBCPP_STD_VER >= 20
  }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI static bool __fits_in_sso(size_type __sz) { return __sz < __min_cap; }

  template <class _Iterator, class _Sentinel>
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
  __assign_trivial(_Iterator __first, _Sentinel __last, size_type __n);

  template <class _Iterator, class _Sentinel>
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __assign_with_sentinel(_Iterator __first, _Sentinel __last);

  template <class _ForwardIterator, class _Sentinel>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 iterator
  __insert_from_safe_copy(size_type __n, size_type __ip, _ForwardIterator __first, _Sentinel __last) {
    size_type __sz  = size();
    size_type __cap = capacity();
    value_type* __p;
    if (__cap - __sz >= __n) {
      __annotate_increase(__n);
      __p                = std::__to_address(__get_pointer());
      size_type __n_move = __sz - __ip;
      if (__n_move != 0)
        traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
    } else {
      __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
      __p = std::__to_address(__get_long_pointer());
    }
    __sz += __n;
    __set_size(__sz);
    traits_type::assign(__p[__sz], value_type());
    for (__p += __ip; __first != __last; ++__p, ++__first)
      traits_type::assign(*__p, *__first);

    return begin() + __ip;
  }

  template <class _Iterator, class _Sentinel>
  _LIBCPP_CONSTEXPR_SINCE_CXX20 iterator
  __insert_with_size(const_iterator __pos, _Iterator __first, _Sentinel __last, size_type __n);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 allocator_type& __alloc() _NOEXCEPT { return __r_.second(); }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR const allocator_type& __alloc() const _NOEXCEPT { return __r_.second(); }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS void
  __set_short_size(size_type __s) _NOEXCEPT {
    _LIBCPP_ASSERT_INTERNAL(__s < __min_cap, "__s should never be greater than or equal to the short string capacity");
    __r_.first().__s.__size_    = __s;
    __r_.first().__s.__is_long_ = false;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS size_type
  __get_short_size() const _NOEXCEPT {
    _LIBCPP_ASSERT_INTERNAL(!__r_.first().__s.__is_long_, "String has to be short when trying to get the short size");
    return __r_.first().__s.__size_;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __set_long_size(size_type __s) _NOEXCEPT {
    __r_.first().__l.__size_ = __s;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type __get_long_size() const _NOEXCEPT {
    return __r_.first().__l.__size_;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __set_size(size_type __s) _NOEXCEPT {
    if (__is_long())
      __set_long_size(__s);
    else
      __set_short_size(__s);
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __set_long_cap(size_type __s) _NOEXCEPT {
    __r_.first().__l.__cap_     = __s / __endian_factor;
    __r_.first().__l.__is_long_ = true;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type __get_long_cap() const _NOEXCEPT {
    return __r_.first().__l.__cap_ * __endian_factor;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __set_long_pointer(pointer __p) _NOEXCEPT {
    __r_.first().__l.__data_ = __p;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pointer __get_long_pointer() _NOEXCEPT {
    return __r_.first().__l.__data_;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_pointer __get_long_pointer() const _NOEXCEPT {
    return __r_.first().__l.__data_;
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pointer __get_short_pointer() _NOEXCEPT {
    return pointer_traits<pointer>::pointer_to(__r_.first().__s.__data_[0]);
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_pointer __get_short_pointer() const _NOEXCEPT {
    return pointer_traits<const_pointer>::pointer_to(__r_.first().__s.__data_[0]);
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 pointer __get_pointer() _NOEXCEPT {
    return __is_long() ? __get_long_pointer() : __get_short_pointer();
  }
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 const_pointer __get_pointer() const _NOEXCEPT {
    return __is_long() ? __get_long_pointer() : __get_short_pointer();
  }

  // The following functions are no-ops outside of AddressSanitizer mode.
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
  __annotate_contiguous_container(const void* __old_mid, const void* __new_mid) const {
    (void)__old_mid;
    (void)__new_mid;
#if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
    const void* __begin = data();
    const void* __end   = data() + capacity() + 1;
    if (__asan_annotate_container_with_allocator<allocator_type>::value && !__libcpp_is_constant_evaluated())
      __sanitizer_annotate_contiguous_container(__begin, __end, __old_mid, __new_mid);
#endif
  }

  // ASan: short string is poisoned if and only if this function returns true.
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __asan_short_string_is_annotated() const _NOEXCEPT {
    return _LIBCPP_SHORT_STRING_ANNOTATIONS_ALLOWED && !__libcpp_is_constant_evaluated();
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __annotate_new(size_type __current_size) const _NOEXCEPT {
    (void) __current_size;
#if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
    if (!__libcpp_is_constant_evaluated() && (__asan_short_string_is_annotated() || __is_long()))
      __annotate_contiguous_container(data() + capacity() + 1, data() + __current_size + 1);
#endif
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __annotate_delete() const _NOEXCEPT {
#if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
    if (!__libcpp_is_constant_evaluated() && (__asan_short_string_is_annotated() || __is_long()))
      __annotate_contiguous_container(data() + size() + 1, data() + capacity() + 1);
#endif
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __annotate_increase(size_type __n) const _NOEXCEPT {
    (void) __n;
#if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
    if (!__libcpp_is_constant_evaluated() && (__asan_short_string_is_annotated() || __is_long()))
      __annotate_contiguous_container(data() + size() + 1, data() + size() + 1 + __n);
#endif
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __annotate_shrink(size_type __old_size) const _NOEXCEPT {
    (void) __old_size;
#if !defined(_LIBCPP_HAS_NO_ASAN) && defined(_LIBCPP_INSTRUMENTED_WITH_ASAN)
    if (!__libcpp_is_constant_evaluated() && (__asan_short_string_is_annotated() || __is_long()))
      __annotate_contiguous_container(data() + __old_size + 1, data() + size() + 1);
#endif
  }

  template <size_type __a>
  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type __align_it(size_type __s) _NOEXCEPT {
    return (__s + (__a - 1)) & ~(__a - 1);
  }
  enum {
    __alignment = 8
  };
  static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type __recommend(size_type __s) _NOEXCEPT {
    if (__s < __min_cap) {
      return static_cast<size_type>(__min_cap) - 1;
    }
    const size_type __boundary = sizeof(value_type) < __alignment ? __alignment / sizeof(value_type) : 1;
    size_type __guess          = __align_it<__boundary>(__s + 1) - 1;
    if (__guess == __min_cap)
      ++__guess;
    return __guess;
  }

  inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void __init(const value_type* __s, size_type __sz, size_type __reserve);
  inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void __init(const value_type* __s, size_type __sz);
  inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void __init(size_type __n, value_type __c);

  // Slow path for the (inlined) copy constructor for 'long' strings.
  // Always externally instantiated and not inlined.
  // Requires that __s is zero terminated.
  // The main reason for this function to exist is because for unstable, we
  // want to allow inlining of the copy constructor. However, we don't want
  // to call the __init() functions as those are marked as inline which may
  // result in over-aggressive inlining by the compiler, where our aim is
  // to only inline the fast path code directly in the ctor.
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE void __init_copy_ctor_external(const value_type* __s, size_type __sz);

  template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> = 0>
  inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void __init(_InputIterator __first, _InputIterator __last);

  template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> = 0>
  inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void __init(_ForwardIterator __first, _ForwardIterator __last);

  template <class _InputIterator, class _Sentinel>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
  __init_with_sentinel(_InputIterator __first, _Sentinel __last);
  template <class _InputIterator, class _Sentinel>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
  __init_with_size(_InputIterator __first, _Sentinel __last, size_type __sz);

  _LIBCPP_CONSTEXPR_SINCE_CXX20
#if _LIBCPP_ABI_VERSION >= 2 //  We want to use the function in the dylib in ABIv1
      _LIBCPP_HIDE_FROM_ABI
#endif
          _LIBCPP_DEPRECATED_("use __grow_by_without_replace") void __grow_by(
              size_type __old_cap,
              size_type __delta_cap,
              size_type __old_sz,
              size_type __n_copy,
              size_type __n_del,
              size_type __n_add = 0);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __grow_by_without_replace(
      size_type __old_cap,
      size_type __delta_cap,
      size_type __old_sz,
      size_type __n_copy,
      size_type __n_del,
      size_type __n_add = 0);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 void __grow_by_and_replace(
      size_type __old_cap,
      size_type __delta_cap,
      size_type __old_sz,
      size_type __n_copy,
      size_type __n_del,
      size_type __n_add,
      const value_type* __p_new_stuff);

  // __assign_no_alias is invoked for assignment operations where we
  // have proof that the input does not alias the current instance.
  // For example, operator=(basic_string) performs a 'self' check.
  template <bool __is_short>
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string& __assign_no_alias(const value_type* __s, size_type __n);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __erase_to_end(size_type __pos) {
    __null_terminate_at(std::__to_address(__get_pointer()), __pos);
  }

  // __erase_external_with_move is invoked for erase() invocations where
  // `n ~= npos`, likely requiring memory moves on the string data.
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE void __erase_external_with_move(size_type __pos, size_type __n);

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __copy_assign_alloc(const basic_string& __str) {
    __copy_assign_alloc(
        __str, integral_constant<bool, __alloc_traits::propagate_on_container_copy_assignment::value>());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __copy_assign_alloc(const basic_string& __str, true_type) {
    if (__alloc() == __str.__alloc())
      __alloc() = __str.__alloc();
    else {
      if (!__str.__is_long()) {
        __clear_and_shrink();
        __alloc() = __str.__alloc();
      } else {
        __annotate_delete();
        allocator_type __a = __str.__alloc();
        auto __allocation  = std::__allocate_at_least(__a, __str.__get_long_cap());
        __begin_lifetime(__allocation.ptr, __allocation.count);
        if (__is_long())
          __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
        __alloc() = std::move(__a);
        __set_long_pointer(__allocation.ptr);
        __set_long_cap(__allocation.count);
        __set_long_size(__str.size());
        __annotate_new(__get_long_size());
      }
    }
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
  __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT {}

#ifndef _LIBCPP_CXX03_LANG
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __move_assign(basic_string& __str, false_type)
      _NOEXCEPT_(__alloc_traits::is_always_equal::value);
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS void
  __move_assign(basic_string& __str, true_type)
#  if _LIBCPP_STD_VER >= 17
      _NOEXCEPT;
#  else
      _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
#  endif
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __move_assign_alloc(basic_string& __str)
      _NOEXCEPT_(!__alloc_traits::propagate_on_container_move_assignment::value ||
                 is_nothrow_move_assignable<allocator_type>::value) {
    __move_assign_alloc(
        __str, integral_constant<bool, __alloc_traits::propagate_on_container_move_assignment::value>());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __move_assign_alloc(basic_string& __c, true_type)
      _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value) {
    __alloc() = std::move(__c.__alloc());
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __move_assign_alloc(basic_string&, false_type) _NOEXCEPT {}

  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string& __assign_external(const value_type* __s);
  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string& __assign_external(const value_type* __s, size_type __n);

  // Assigns the value in __s, guaranteed to be __n < __min_cap in length.
  inline _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string& __assign_short(const value_type* __s, size_type __n) {
    size_type __old_size = size();
    if (__n > __old_size)
      __annotate_increase(__n - __old_size);
    pointer __p =
        __is_long() ? (__set_long_size(__n), __get_long_pointer()) : (__set_short_size(__n), __get_short_pointer());
    traits_type::move(std::__to_address(__p), __s, __n);
    traits_type::assign(__p[__n], value_type());
    if (__old_size > __n)
      __annotate_shrink(__old_size);
    return *this;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string&
  __null_terminate_at(value_type* __p, size_type __newsz) {
    size_type __old_size = size();
    if (__newsz > __old_size)
      __annotate_increase(__newsz - __old_size);
    __set_size(__newsz);
    traits_type::assign(__p[__newsz], value_type());
    if (__old_size > __newsz)
      __annotate_shrink(__old_size);
    return *this;
  }

  template <class _Tp>
  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool __addr_in_range(const _Tp& __v) const {
    return std::__is_pointer_in_range(data(), data() + size() + 1, std::addressof(__v));
  }

  _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI void __throw_length_error() const {
    std::__throw_length_error("basic_string");
  }

  _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI void __throw_out_of_range() const {
    std::__throw_out_of_range("basic_string");
  }

  friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(const basic_string&, const basic_string&);
  friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(const value_type*, const basic_string&);
  friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(value_type, const basic_string&);
  friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(const basic_string&, const value_type*);
  friend _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string operator+ <>(const basic_string&, value_type);
};

// These declarations must appear before any functions are implicitly used
// so that they have the correct visibility specifier.
#define _LIBCPP_DECLARE(...) extern template __VA_ARGS__;
#ifdef _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
_LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_DECLARE, char)
#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
_LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_DECLARE, wchar_t)
#  endif
#else
_LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_DECLARE, char)
#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
_LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_DECLARE, wchar_t)
#  endif
#endif
#undef _LIBCPP_DECLARE

#if _LIBCPP_STD_VER >= 17
template <class _InputIterator,
          class _CharT     = __iter_value_type<_InputIterator>,
          class _Allocator = allocator<_CharT>,
          class            = enable_if_t<__has_input_iterator_category<_InputIterator>::value>,
          class            = enable_if_t<__is_allocator<_Allocator>::value> >
basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
    -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;

template <class _CharT,
          class _Traits,
          class _Allocator = allocator<_CharT>,
          class            = enable_if_t<__is_allocator<_Allocator>::value> >
explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
    -> basic_string<_CharT, _Traits, _Allocator>;

template <class _CharT,
          class _Traits,
          class _Allocator = allocator<_CharT>,
          class            = enable_if_t<__is_allocator<_Allocator>::value>,
          class _Sz        = typename allocator_traits<_Allocator>::size_type >
basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _Allocator())
    -> basic_string<_CharT, _Traits, _Allocator>;
#endif

#if _LIBCPP_STD_VER >= 23
template <ranges::input_range _Range,
          class _Allocator = allocator<ranges::range_value_t<_Range>>,
          class            = enable_if_t<__is_allocator<_Allocator>::value> >
basic_string(from_range_t, _Range&&, _Allocator = _Allocator())
    -> basic_string<ranges::range_value_t<_Range>, char_traits<ranges::range_value_t<_Range>>, _Allocator>;
#endif

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz, size_type __reserve) {
  if (__libcpp_is_constant_evaluated())
    __r_.first() = __rep();
  if (__reserve > max_size())
    __throw_length_error();
  pointer __p;
  if (__fits_in_sso(__reserve)) {
    __set_short_size(__sz);
    __p = __get_short_pointer();
  } else {
    auto __allocation = std::__allocate_at_least(__alloc(), __recommend(__reserve) + 1);
    __p               = __allocation.ptr;
    __begin_lifetime(__p, __allocation.count);
    __set_long_pointer(__p);
    __set_long_cap(__allocation.count);
    __set_long_size(__sz);
  }
  traits_type::copy(std::__to_address(__p), __s, __sz);
  traits_type::assign(__p[__sz], value_type());
  __annotate_new(__sz);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz) {
  if (__libcpp_is_constant_evaluated())
    __r_.first() = __rep();
  if (__sz > max_size())
    __throw_length_error();
  pointer __p;
  if (__fits_in_sso(__sz)) {
    __set_short_size(__sz);
    __p = __get_short_pointer();
  } else {
    auto __allocation = std::__allocate_at_least(__alloc(), __recommend(__sz) + 1);
    __p               = __allocation.ptr;
    __begin_lifetime(__p, __allocation.count);
    __set_long_pointer(__p);
    __set_long_cap(__allocation.count);
    __set_long_size(__sz);
  }
  traits_type::copy(std::__to_address(__p), __s, __sz);
  traits_type::assign(__p[__sz], value_type());
  __annotate_new(__sz);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE void
basic_string<_CharT, _Traits, _Allocator>::__init_copy_ctor_external(const value_type* __s, size_type __sz) {
  if (__libcpp_is_constant_evaluated())
    __r_.first() = __rep();

  pointer __p;
  if (__fits_in_sso(__sz)) {
    __p = __get_short_pointer();
    __set_short_size(__sz);
  } else {
    if (__sz > max_size())
      __throw_length_error();
    auto __allocation = std::__allocate_at_least(__alloc(), __recommend(__sz) + 1);
    __p               = __allocation.ptr;
    __begin_lifetime(__p, __allocation.count);
    __set_long_pointer(__p);
    __set_long_cap(__allocation.count);
    __set_long_size(__sz);
  }
  traits_type::copy(std::__to_address(__p), __s, __sz + 1);
  __annotate_new(__sz);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c) {
  if (__libcpp_is_constant_evaluated())
    __r_.first() = __rep();

  if (__n > max_size())
    __throw_length_error();
  pointer __p;
  if (__fits_in_sso(__n)) {
    __set_short_size(__n);
    __p = __get_short_pointer();
  } else {
    auto __allocation = std::__allocate_at_least(__alloc(), __recommend(__n) + 1);
    __p               = __allocation.ptr;
    __begin_lifetime(__p, __allocation.count);
    __set_long_pointer(__p);
    __set_long_cap(__allocation.count);
    __set_long_size(__n);
  }
  traits_type::assign(std::__to_address(__p), __n, __c);
  traits_type::assign(__p[__n], value_type());
  __annotate_new(__n);
}

template <class _CharT, class _Traits, class _Allocator>
template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last) {
  __init_with_sentinel(std::move(__first), std::move(__last));
}

template <class _CharT, class _Traits, class _Allocator>
template <class _InputIterator, class _Sentinel>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__init_with_sentinel(_InputIterator __first, _Sentinel __last) {
  __r_.first() = __rep();
  __annotate_new(0);

#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
  try {
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
    for (; __first != __last; ++__first)
      push_back(*__first);
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
  } catch (...) {
    __annotate_delete();
    if (__is_long())
      __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
    throw;
  }
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
}

template <class _CharT, class _Traits, class _Allocator>
template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last) {
  size_type __sz = static_cast<size_type>(std::distance(__first, __last));
  __init_with_size(__first, __last, __sz);
}

template <class _CharT, class _Traits, class _Allocator>
template <class _InputIterator, class _Sentinel>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__init_with_size(_InputIterator __first, _Sentinel __last, size_type __sz) {
  if (__libcpp_is_constant_evaluated())
    __r_.first() = __rep();

  if (__sz > max_size())
    __throw_length_error();

  pointer __p;
  if (__fits_in_sso(__sz)) {
    __set_short_size(__sz);
    __p = __get_short_pointer();

  } else {
    auto __allocation = std::__allocate_at_least(__alloc(), __recommend(__sz) + 1);
    __p               = __allocation.ptr;
    __begin_lifetime(__p, __allocation.count);
    __set_long_pointer(__p);
    __set_long_cap(__allocation.count);
    __set_long_size(__sz);
  }

#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
  try {
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
    for (; __first != __last; ++__first, (void)++__p)
      traits_type::assign(*__p, *__first);
    traits_type::assign(*__p, value_type());
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
  } catch (...) {
    if (__is_long())
      __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
    throw;
  }
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
  __annotate_new(__sz);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace(
    size_type __old_cap,
    size_type __delta_cap,
    size_type __old_sz,
    size_type __n_copy,
    size_type __n_del,
    size_type __n_add,
    const value_type* __p_new_stuff) {
  size_type __ms = max_size();
  if (__delta_cap > __ms - __old_cap - 1)
    __throw_length_error();
  pointer __old_p = __get_pointer();
  size_type __cap =
      __old_cap < __ms / 2 - __alignment ? __recommend(std::max(__old_cap + __delta_cap, 2 * __old_cap)) : __ms - 1;
  __annotate_delete();
  auto __allocation = std::__allocate_at_least(__alloc(), __cap + 1);
  pointer __p       = __allocation.ptr;
  __begin_lifetime(__p, __allocation.count);
  if (__n_copy != 0)
    traits_type::copy(std::__to_address(__p), std::__to_address(__old_p), __n_copy);
  if (__n_add != 0)
    traits_type::copy(std::__to_address(__p) + __n_copy, __p_new_stuff, __n_add);
  size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
  if (__sec_cp_sz != 0)
    traits_type::copy(
        std::__to_address(__p) + __n_copy + __n_add, std::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
  if (__old_cap + 1 != __min_cap)
    __alloc_traits::deallocate(__alloc(), __old_p, __old_cap + 1);
  __set_long_pointer(__p);
  __set_long_cap(__allocation.count);
  __old_sz = __n_copy + __n_add + __sec_cp_sz;
  __set_long_size(__old_sz);
  traits_type::assign(__p[__old_sz], value_type());
  __annotate_new(__old_cap + __delta_cap);
}

// __grow_by is deprecated because it does not set the size. It may not update the size when the size is changed, and it
// may also not set the size at all when the string was short initially. This leads to unpredictable size value. It is
// not removed or changed to avoid breaking the ABI.
template <class _CharT, class _Traits, class _Allocator>
void _LIBCPP_CONSTEXPR_SINCE_CXX20
#if _LIBCPP_ABI_VERSION >= 2 // We want to use the function in the dylib in ABIv1
    _LIBCPP_HIDE_FROM_ABI
#endif
    _LIBCPP_DEPRECATED_("use __grow_by_without_replace") basic_string<_CharT, _Traits, _Allocator>::__grow_by(
        size_type __old_cap,
        size_type __delta_cap,
        size_type __old_sz,
        size_type __n_copy,
        size_type __n_del,
        size_type __n_add) {
  size_type __ms = max_size();
  if (__delta_cap > __ms - __old_cap)
    __throw_length_error();
  pointer __old_p = __get_pointer();
  size_type __cap =
      __old_cap < __ms / 2 - __alignment ? __recommend(std::max(__old_cap + __delta_cap, 2 * __old_cap)) : __ms - 1;
  __annotate_delete();
  auto __allocation = std::__allocate_at_least(__alloc(), __cap + 1);
  pointer __p       = __allocation.ptr;
  __begin_lifetime(__p, __allocation.count);
  if (__n_copy != 0)
    traits_type::copy(std::__to_address(__p), std::__to_address(__old_p), __n_copy);
  size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
  if (__sec_cp_sz != 0)
    traits_type::copy(
        std::__to_address(__p) + __n_copy + __n_add, std::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
  if (__old_cap + 1 != __min_cap)
    __alloc_traits::deallocate(__alloc(), __old_p, __old_cap + 1);
  __set_long_pointer(__p);
  __set_long_cap(__allocation.count);
}

template <class _CharT, class _Traits, class _Allocator>
void _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI
basic_string<_CharT, _Traits, _Allocator>::__grow_by_without_replace(
    size_type __old_cap,
    size_type __delta_cap,
    size_type __old_sz,
    size_type __n_copy,
    size_type __n_del,
    size_type __n_add) {
  _LIBCPP_SUPPRESS_DEPRECATED_PUSH
  __grow_by(__old_cap, __delta_cap, __old_sz, __n_copy, __n_del, __n_add);
  _LIBCPP_SUPPRESS_DEPRECATED_POP
  __set_long_size(__old_sz - __n_del + __n_add);
  __annotate_new(__old_sz - __n_del + __n_add);
}

// assign

template <class _CharT, class _Traits, class _Allocator>
template <bool __is_short>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(const value_type* __s, size_type __n) {
  size_type __cap = __is_short ? static_cast<size_type>(__min_cap) : __get_long_cap();
  if (__n < __cap) {
    size_type __old_size = __is_short ? __get_short_size() : __get_long_size();
    if (__n > __old_size)
      __annotate_increase(__n - __old_size);
    pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
    __is_short ? __set_short_size(__n) : __set_long_size(__n);
    traits_type::copy(std::__to_address(__p), __s, __n);
    traits_type::assign(__p[__n], value_type());
    if (__old_size > __n)
      __annotate_shrink(__old_size);
  } else {
    size_type __sz = __is_short ? __get_short_size() : __get_long_size();
    __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
  }
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s, size_type __n) {
  size_type __cap = capacity();
  if (__cap >= __n) {
    size_type __old_size = size();
    if (__n > __old_size)
      __annotate_increase(__n - __old_size);
    value_type* __p = std::__to_address(__get_pointer());
    traits_type::move(__p, __s, __n);
    return __null_terminate_at(__p, __n);
  } else {
    size_type __sz = size();
    __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
    return *this;
  }
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n) {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::assign received nullptr");
  return (__builtin_constant_p(__n) && __fits_in_sso(__n)) ? __assign_short(__s, __n) : __assign_external(__s, __n);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c) {
  size_type __cap      = capacity();
  size_type __old_size = size();
  if (__cap < __n) {
    size_type __sz = size();
    __grow_by_without_replace(__cap, __n - __cap, __sz, 0, __sz);
    __annotate_increase(__n);
  } else if (__n > __old_size)
    __annotate_increase(__n - __old_size);
  value_type* __p = std::__to_address(__get_pointer());
  traits_type::assign(__p, __n, __c);
  return __null_terminate_at(__p, __n);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c) {
  pointer __p;
  size_type __old_size = size();
  if (__old_size == 0)
    __annotate_increase(1);
  if (__is_long()) {
    __p = __get_long_pointer();
    __set_long_size(1);
  } else {
    __p = __get_short_pointer();
    __set_short_size(1);
  }
  traits_type::assign(*__p, __c);
  traits_type::assign(*++__p, value_type());
  if (__old_size > 1)
    __annotate_shrink(__old_size);
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str) {
  if (this != std::addressof(__str)) {
    __copy_assign_alloc(__str);
    if (!__is_long()) {
      if (!__str.__is_long()) {
        size_type __old_size = __get_short_size();
        if (__get_short_size() < __str.__get_short_size())
          __annotate_increase(__str.__get_short_size() - __get_short_size());
        __r_.first() = __str.__r_.first();
        if (__old_size > __get_short_size())
          __annotate_shrink(__old_size);
      } else {
        return __assign_no_alias<true>(__str.data(), __str.size());
      }
    } else {
      return __assign_no_alias<false>(__str.data(), __str.size());
    }
  }
  return *this;
}

#ifndef _LIBCPP_CXX03_LANG

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
    _NOEXCEPT_(__alloc_traits::is_always_equal::value) {
  if (__alloc() != __str.__alloc())
    assign(__str);
  else
    __move_assign(__str, true_type());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_STRING_INTERNAL_MEMORY_ACCESS void
basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
#  if _LIBCPP_STD_VER >= 17
    _NOEXCEPT
#  else
    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
#  endif
{
  __annotate_delete();
  if (__is_long()) {
    __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
#  if _LIBCPP_STD_VER <= 14
    if (!is_nothrow_move_assignable<allocator_type>::value) {
      __set_short_size(0);
      traits_type::assign(__get_short_pointer()[0], value_type());
      __annotate_new(0);
    }
#  endif
  }
  size_type __str_old_size = __str.size();
  bool __str_was_short     = !__str.__is_long();

  __move_assign_alloc(__str);
  __r_.first() = __str.__r_.first();
  __str.__set_short_size(0);
  traits_type::assign(__str.__get_short_pointer()[0], value_type());

  if (__str_was_short && this != &__str)
    __str.__annotate_shrink(__str_old_size);
  else
    // ASan annotations: was long, so object memory is unpoisoned as new.
    // Or is same as *this, and __annotate_delete() was called.
    __str.__annotate_new(0);

  // ASan annotations: Guard against `std::string s; s = std::move(s);`
  // You can find more here: https://en.cppreference.com/w/cpp/utility/move
  // Quote: "Unless otherwise specified, all standard library objects that have been moved
  // from are placed in a "valid but unspecified state", meaning the object's class
  // invariants hold (so functions without preconditions, such as the assignment operator,
  // can be safely used on the object after it was moved from):"
  // Quote: "v = std::move(v); // the value of v is unspecified"
  if (!__is_long() && &__str != this)
    // If it is long string, delete was never called on original __str's buffer.
    __annotate_new(__get_short_size());
}

#endif

template <class _CharT, class _Traits, class _Allocator>
template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last) {
  __assign_with_sentinel(__first, __last);
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
template <class _InputIterator, class _Sentinel>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__assign_with_sentinel(_InputIterator __first, _Sentinel __last) {
  const basic_string __temp(__init_with_sentinel_tag(), std::move(__first), std::move(__last), __alloc());
  assign(__temp.data(), __temp.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last) {
  if (__string_is_trivial_iterator<_ForwardIterator>::value) {
    size_type __n = static_cast<size_type>(std::distance(__first, __last));
    __assign_trivial(__first, __last, __n);
  } else {
    __assign_with_sentinel(__first, __last);
  }

  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Iterator, class _Sentinel>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void
basic_string<_CharT, _Traits, _Allocator>::__assign_trivial(_Iterator __first, _Sentinel __last, size_type __n) {
  _LIBCPP_ASSERT_INTERNAL(
      __string_is_trivial_iterator<_Iterator>::value, "The iterator type given to `__assign_trivial` must be trivial");

  size_type __old_size = size();
  size_type __cap      = capacity();
  if (__cap < __n) {
    // Unlike `append` functions, if the input range points into the string itself, there is no case that the input
    // range could get invalidated by reallocation:
    // 1. If the input range is a subset of the string itself, its size cannot exceed the capacity of the string,
    //    thus no reallocation would happen.
    // 2. In the exotic case where the input range is the byte representation of the string itself, the string
    //    object itself stays valid even if reallocation happens.
    size_type __sz = size();
    __grow_by_without_replace(__cap, __n - __cap, __sz, 0, __sz);
    __annotate_increase(__n);
  } else if (__n > __old_size)
    __annotate_increase(__n - __old_size);
  pointer __p = __get_pointer();
  for (; __first != __last; ++__p, (void)++__first)
    traits_type::assign(*__p, *__first);
  traits_type::assign(*__p, value_type());
  __set_size(__n);
  if (__n < __old_size)
    __annotate_shrink(__old_size);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const basic_string& __str, size_type __pos, size_type __n) {
  size_type __sz = __str.size();
  if (__pos > __sz)
    __throw_out_of_range();
  return assign(__str.data() + __pos, std::min(__n, __sz - __pos));
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp,
          __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                            !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
                        int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const _Tp& __t, size_type __pos, size_type __n) {
  __self_view __sv = __t;
  size_type __sz   = __sv.size();
  if (__pos > __sz)
    __throw_out_of_range();
  return assign(__sv.data() + __pos, std::min(__n, __sz - __pos));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s) {
  return __assign_external(__s, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s) {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::assign received nullptr");
  return __builtin_constant_p(*__s)
           ? (__fits_in_sso(traits_type::length(__s)) ? __assign_short(__s, traits_type::length(__s))
                                                      : __assign_external(__s, traits_type::length(__s)))
           : __assign_external(__s);
}
// append

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n) {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::append received nullptr");
  size_type __cap = capacity();
  size_type __sz  = size();
  if (__cap - __sz >= __n) {
    if (__n) {
      __annotate_increase(__n);
      value_type* __p = std::__to_address(__get_pointer());
      traits_type::copy(__p + __sz, __s, __n);
      __sz += __n;
      __set_size(__sz);
      traits_type::assign(__p[__sz], value_type());
    }
  } else
    __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __sz, 0, __n, __s);
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c) {
  if (__n) {
    size_type __cap = capacity();
    size_type __sz  = size();
    if (__cap - __sz < __n)
      __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0);
    __annotate_increase(__n);
    pointer __p = __get_pointer();
    traits_type::assign(std::__to_address(__p) + __sz, __n, __c);
    __sz += __n;
    __set_size(__sz);
    traits_type::assign(__p[__sz], value_type());
  }
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 inline void
basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n) {
  if (__n) {
    size_type __cap = capacity();
    size_type __sz  = size();
    if (__cap - __sz < __n)
      __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0);
    __annotate_increase(__n);
    pointer __p = __get_pointer();
    __sz += __n;
    __set_size(__sz);
    traits_type::assign(__p[__sz], value_type());
  }
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::push_back(value_type __c) {
  bool __is_short = !__is_long();
  size_type __cap;
  size_type __sz;
  if (__is_short) {
    __cap = __min_cap - 1;
    __sz  = __get_short_size();
  } else {
    __cap = __get_long_cap() - 1;
    __sz  = __get_long_size();
  }
  if (__sz == __cap) {
    __grow_by_without_replace(__cap, 1, __sz, __sz, 0);
    __annotate_increase(1);
    __is_short = false; // the string is always long after __grow_by
  } else
    __annotate_increase(1);
  pointer __p = __get_pointer();
  if (__is_short) {
    __p = __get_short_pointer() + __sz;
    __set_short_size(__sz + 1);
  } else {
    __p = __get_long_pointer() + __sz;
    __set_long_size(__sz + 1);
  }
  traits_type::assign(*__p, __c);
  traits_type::assign(*++__p, value_type());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::append(_ForwardIterator __first, _ForwardIterator __last) {
  size_type __sz  = size();
  size_type __cap = capacity();
  size_type __n   = static_cast<size_type>(std::distance(__first, __last));
  if (__n) {
    if (__string_is_trivial_iterator<_ForwardIterator>::value && !__addr_in_range(*__first)) {
      if (__cap - __sz < __n)
        __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __sz, 0);
      __annotate_increase(__n);
      pointer __p = __get_pointer() + __sz;
      for (; __first != __last; ++__p, (void)++__first)
        traits_type::assign(*__p, *__first);
      traits_type::assign(*__p, value_type());
      __set_size(__sz + __n);
    } else {
      const basic_string __temp(__first, __last, __alloc());
      append(__temp.data(), __temp.size());
    }
  }
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str, size_type __pos, size_type __n) {
  size_type __sz = __str.size();
  if (__pos > __sz)
    __throw_out_of_range();
  return append(__str.data() + __pos, std::min(__n, __sz - __pos));
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp,
          __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                            !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
                        int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::append(const _Tp& __t, size_type __pos, size_type __n) {
  __self_view __sv = __t;
  size_type __sz   = __sv.size();
  if (__pos > __sz)
    __throw_out_of_range();
  return append(__sv.data() + __pos, std::min(__n, __sz - __pos));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s) {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::append received nullptr");
  return append(__s, traits_type::length(__s));
}

// insert

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n) {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::insert received nullptr");
  size_type __sz = size();
  if (__pos > __sz)
    __throw_out_of_range();
  size_type __cap = capacity();
  if (__cap - __sz >= __n) {
    if (__n) {
      __annotate_increase(__n);
      value_type* __p    = std::__to_address(__get_pointer());
      size_type __n_move = __sz - __pos;
      if (__n_move != 0) {
        if (std::__is_pointer_in_range(__p + __pos, __p + __sz, __s))
          __s += __n;
        traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
      }
      traits_type::move(__p + __pos, __s, __n);
      __sz += __n;
      __set_size(__sz);
      traits_type::assign(__p[__sz], value_type());
    }
  } else
    __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n, __s);
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n, value_type __c) {
  size_type __sz = size();
  if (__pos > __sz)
    __throw_out_of_range();
  if (__n) {
    size_type __cap = capacity();
    value_type* __p;
    if (__cap - __sz >= __n) {
      __annotate_increase(__n);
      __p                = std::__to_address(__get_pointer());
      size_type __n_move = __sz - __pos;
      if (__n_move != 0)
        traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
    } else {
      __grow_by_without_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
      __p = std::__to_address(__get_long_pointer());
    }
    traits_type::assign(__p + __pos, __n, __c);
    __sz += __n;
    __set_size(__sz);
    traits_type::assign(__p[__sz], value_type());
  }
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
template <class _InputIterator, __enable_if_t<__has_exactly_input_iterator_category<_InputIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::iterator
basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last) {
  const basic_string __temp(__first, __last, __alloc());
  return insert(__pos, __temp.data(), __temp.data() + __temp.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _ForwardIterator, __enable_if_t<__has_forward_iterator_category<_ForwardIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::iterator
basic_string<_CharT, _Traits, _Allocator>::insert(
    const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last) {
  auto __n = static_cast<size_type>(std::distance(__first, __last));
  return __insert_with_size(__pos, __first, __last, __n);
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Iterator, class _Sentinel>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::iterator
basic_string<_CharT, _Traits, _Allocator>::__insert_with_size(
    const_iterator __pos, _Iterator __first, _Sentinel __last, size_type __n) {
  size_type __ip = static_cast<size_type>(__pos - begin());
  if (__n == 0)
    return begin() + __ip;

  if (__string_is_trivial_iterator<_Iterator>::value && !__addr_in_range(*__first)) {
    return __insert_from_safe_copy(__n, __ip, __first, __last);
  } else {
    const basic_string __temp(__init_with_sentinel_tag(), __first, __last, __alloc());
    return __insert_from_safe_copy(__n, __ip, __temp.begin(), __temp.end());
  }
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::insert(
    size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n) {
  size_type __str_sz = __str.size();
  if (__pos2 > __str_sz)
    __throw_out_of_range();
  return insert(__pos1, __str.data() + __pos2, std::min(__n, __str_sz - __pos2));
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp,
          __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                            !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
                        int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n) {
  __self_view __sv   = __t;
  size_type __str_sz = __sv.size();
  if (__pos2 > __str_sz)
    __throw_out_of_range();
  return insert(__pos1, __sv.data() + __pos2, std::min(__n, __str_sz - __pos2));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s) {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::insert received nullptr");
  return insert(__pos, __s, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::iterator
basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_type __c) {
  size_type __ip  = static_cast<size_type>(__pos - begin());
  size_type __sz  = size();
  size_type __cap = capacity();
  value_type* __p;
  if (__cap == __sz) {
    __grow_by_without_replace(__cap, 1, __sz, __ip, 0, 1);
    __p = std::__to_address(__get_long_pointer());
  } else {
    __annotate_increase(1);
    __p                = std::__to_address(__get_pointer());
    size_type __n_move = __sz - __ip;
    if (__n_move != 0)
      traits_type::move(__p + __ip + 1, __p + __ip, __n_move);
  }
  traits_type::assign(__p[__ip], __c);
  traits_type::assign(__p[++__sz], value_type());
  __set_size(__sz);
  return begin() + static_cast<difference_type>(__ip);
}

// replace

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::replace(
    size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK {
  _LIBCPP_ASSERT_NON_NULL(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
  size_type __sz = size();
  if (__pos > __sz)
    __throw_out_of_range();
  __n1            = std::min(__n1, __sz - __pos);
  size_type __cap = capacity();
  if (__cap - __sz + __n1 >= __n2) {
    value_type* __p = std::__to_address(__get_pointer());
    if (__n1 != __n2) {
      if (__n2 > __n1)
        __annotate_increase(__n2 - __n1);
      size_type __n_move = __sz - __pos - __n1;
      if (__n_move != 0) {
        if (__n1 > __n2) {
          traits_type::move(__p + __pos, __s, __n2);
          traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
          return __null_terminate_at(__p, __sz + (__n2 - __n1));
        }
        if (std::__is_pointer_in_range(__p + __pos + 1, __p + __sz, __s)) {
          if (__p + __pos + __n1 <= __s)
            __s += __n2 - __n1;
          else // __p + __pos < __s < __p + __pos + __n1
          {
            traits_type::move(__p + __pos, __s, __n1);
            __pos += __n1;
            __s += __n2;
            __n2 -= __n1;
            __n1 = 0;
          }
        }
        traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
      }
    }
    traits_type::move(__p + __pos, __s, __n2);
    return __null_terminate_at(__p, __sz + (__n2 - __n1));
  } else
    __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c) {
  size_type __sz = size();
  if (__pos > __sz)
    __throw_out_of_range();
  __n1            = std::min(__n1, __sz - __pos);
  size_type __cap = capacity();
  value_type* __p;
  if (__cap - __sz + __n1 >= __n2) {
    __p = std::__to_address(__get_pointer());
    if (__n1 != __n2) {
      if (__n2 > __n1)
        __annotate_increase(__n2 - __n1);
      size_type __n_move = __sz - __pos - __n1;
      if (__n_move != 0)
        traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
    }
  } else {
    __grow_by_without_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
    __p = std::__to_address(__get_long_pointer());
  }
  traits_type::assign(__p + __pos, __n2, __c);
  return __null_terminate_at(__p, __sz - (__n1 - __n2));
}

template <class _CharT, class _Traits, class _Allocator>
template <class _InputIterator, __enable_if_t<__has_input_iterator_category<_InputIterator>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::replace(
    const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2) {
  const basic_string __temp(__j1, __j2, __alloc());
  return replace(__i1, __i2, __temp);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::replace(
    size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2) {
  size_type __str_sz = __str.size();
  if (__pos2 > __str_sz)
    __throw_out_of_range();
  return replace(__pos1, __n1, __str.data() + __pos2, std::min(__n2, __str_sz - __pos2));
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp,
          __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                            !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
                        int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::replace(
    size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2) {
  __self_view __sv   = __t;
  size_type __str_sz = __sv.size();
  if (__pos2 > __str_sz)
    __throw_out_of_range();
  return replace(__pos1, __n1, __sv.data() + __pos2, std::min(__n2, __str_sz - __pos2));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s) {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::replace received nullptr");
  return replace(__pos, __n1, __s, traits_type::length(__s));
}

// erase

// 'externally instantiated' erase() implementation, called when __n != npos.
// Does not check __pos against size()
template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_NOINLINE void
basic_string<_CharT, _Traits, _Allocator>::__erase_external_with_move(size_type __pos, size_type __n) {
  if (__n) {
    size_type __sz     = size();
    value_type* __p    = std::__to_address(__get_pointer());
    __n                = std::min(__n, __sz - __pos);
    size_type __n_move = __sz - __pos - __n;
    if (__n_move != 0)
      traits_type::move(__p + __pos, __p + __pos + __n, __n_move);
    __null_terminate_at(__p, __sz - __n);
  }
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>&
basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos, size_type __n) {
  if (__pos > size())
    __throw_out_of_range();
  if (__n == npos) {
    __erase_to_end(__pos);
  } else {
    __erase_external_with_move(__pos, __n);
  }
  return *this;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::iterator
basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos) {
  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
      __pos != end(), "string::erase(iterator) called with a non-dereferenceable iterator");
  iterator __b  = begin();
  size_type __r = static_cast<size_type>(__pos - __b);
  erase(__r, 1);
  return __b + static_cast<difference_type>(__r);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::iterator
basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last) {
  _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "string::erase(first, last) called with invalid range");
  iterator __b  = begin();
  size_type __r = static_cast<size_type>(__first - __b);
  erase(__r, static_cast<size_type>(__last - __first));
  return __b + static_cast<difference_type>(__r);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::pop_back() {
  _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string::pop_back(): string is already empty");
  __erase_to_end(size() - 1);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT {
  size_type __old_size = size();
  if (__is_long()) {
    traits_type::assign(*__get_long_pointer(), value_type());
    __set_long_size(0);
  } else {
    traits_type::assign(*__get_short_pointer(), value_type());
    __set_short_size(0);
  }
  __annotate_shrink(__old_size);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::resize(size_type __n, value_type __c) {
  size_type __sz = size();
  if (__n > __sz)
    append(__n - __sz, __c);
  else
    __erase_to_end(__n);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 inline void
basic_string<_CharT, _Traits, _Allocator>::__resize_default_init(size_type __n) {
  size_type __sz = size();
  if (__n > __sz) {
    __append_default_init(__n - __sz);
  } else
    __erase_to_end(__n);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __requested_capacity) {
  if (__requested_capacity > max_size())
    __throw_length_error();

  // Make sure reserve(n) never shrinks. This is technically only required in C++20
  // and later (since P0966R1), however we provide consistent behavior in all Standard
  // modes because this function is instantiated in the shared library.
  if (__requested_capacity <= capacity())
    return;

  size_type __target_capacity = std::max(__requested_capacity, size());
  __target_capacity           = __recommend(__target_capacity);
  if (__target_capacity == capacity())
    return;

  __shrink_or_extend(__target_capacity);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::shrink_to_fit() _NOEXCEPT {
  size_type __target_capacity = __recommend(size());
  if (__target_capacity == capacity())
    return;

  __shrink_or_extend(__target_capacity);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void
basic_string<_CharT, _Traits, _Allocator>::__shrink_or_extend(size_type __target_capacity) {
  __annotate_delete();
  size_type __cap = capacity();
  size_type __sz  = size();

  pointer __new_data, __p;
  bool __was_long, __now_long;
  if (__fits_in_sso(__target_capacity)) {
    __was_long = true;
    __now_long = false;
    __new_data = __get_short_pointer();
    __p        = __get_long_pointer();
  } else {
    if (__target_capacity > __cap) {
      auto __allocation = std::__allocate_at_least(__alloc(), __target_capacity + 1);
      __new_data        = __allocation.ptr;
      __target_capacity = __allocation.count - 1;
    } else {
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
      try {
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
        auto __allocation = std::__allocate_at_least(__alloc(), __target_capacity + 1);
        __new_data        = __allocation.ptr;
        __target_capacity = __allocation.count - 1;
#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
      } catch (...) {
        return;
      }
#else  // _LIBCPP_HAS_NO_EXCEPTIONS
      if (__new_data == nullptr)
        return;
#endif // _LIBCPP_HAS_NO_EXCEPTIONS
    }
    __begin_lifetime(__new_data, __target_capacity + 1);
    __now_long = true;
    __was_long = __is_long();
    __p        = __get_pointer();
  }
  traits_type::copy(std::__to_address(__new_data), std::__to_address(__p), size() + 1);
  if (__was_long)
    __alloc_traits::deallocate(__alloc(), __p, __cap + 1);
  if (__now_long) {
    __set_long_cap(__target_capacity + 1);
    __set_long_size(__sz);
    __set_long_pointer(__new_data);
  } else
    __set_short_size(__sz);
  __annotate_new(__sz);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::const_reference
basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const {
  if (__n >= size())
    __throw_out_of_range();
  return (*this)[__n];
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::reference
basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) {
  if (__n >= size())
    __throw_out_of_range();
  return (*this)[__n];
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::copy(value_type* __s, size_type __n, size_type __pos) const {
  size_type __sz = size();
  if (__pos > __sz)
    __throw_out_of_range();
  size_type __rlen = std::min(__n, __sz - __pos);
  traits_type::copy(__s, data() + __pos, __rlen);
  return __rlen;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
#if _LIBCPP_STD_VER >= 14
    _NOEXCEPT
#else
    _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value || __is_nothrow_swappable<allocator_type>::value)
#endif
{
  _LIBCPP_ASSERT_COMPATIBLE_ALLOCATOR(
      __alloc_traits::propagate_on_container_swap::value || __alloc_traits::is_always_equal::value ||
          __alloc() == __str.__alloc(),
      "swapping non-equal allocators");
  if (!__is_long())
    __annotate_delete();
  if (this != &__str && !__str.__is_long())
    __str.__annotate_delete();
  std::swap(__r_.first(), __str.__r_.first());
  std::__swap_allocator(__alloc(), __str.__alloc());
  if (!__is_long())
    __annotate_new(__get_short_size());
  if (this != &__str && !__str.__is_long())
    __str.__annotate_new(__str.__get_short_size());
}

// find

template <class _Traits>
struct _LIBCPP_HIDDEN __traits_eq {
  typedef typename _Traits::char_type char_type;
  _LIBCPP_HIDE_FROM_ABI bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT {
    return _Traits::eq(__x, __y);
  }
};

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::find(): received nullptr");
  return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str, size_type __pos) const _NOEXCEPT {
  return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __str.data(), __pos, __str.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find(const _Tp& __t, size_type __pos) const _NOEXCEPT {
  __self_view __sv = __t;
  return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __sv.data(), __pos, __sv.size());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s, size_type __pos) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::find(): received nullptr");
  return std::__str_find<value_type, size_type, traits_type, npos>(
      data(), size(), __s, __pos, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find(value_type __c, size_type __pos) const _NOEXCEPT {
  return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}

// rfind

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::rfind(
    const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
  return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str, size_type __pos) const _NOEXCEPT {
  return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __str.data(), __pos, __str.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::rfind(const _Tp& __t, size_type __pos) const _NOEXCEPT {
  __self_view __sv = __t;
  return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __sv.data(), __pos, __sv.size());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s, size_type __pos) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::rfind(): received nullptr");
  return std::__str_rfind<value_type, size_type, traits_type, npos>(
      data(), size(), __s, __pos, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c, size_type __pos) const _NOEXCEPT {
  return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}

// find_first_of

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_of(
    const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
  return std::__str_find_first_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_of(const basic_string& __str, size_type __pos) const _NOEXCEPT {
  return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
      data(), size(), __str.data(), __pos, __str.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_of(const _Tp& __t, size_type __pos) const _NOEXCEPT {
  __self_view __sv = __t;
  return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
      data(), size(), __sv.data(), __pos, __sv.size());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s, size_type __pos) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::find_first_of(): received nullptr");
  return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
      data(), size(), __s, __pos, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_of(value_type __c, size_type __pos) const _NOEXCEPT {
  return find(__c, __pos);
}

// find_last_of

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_of(
    const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
  return std::__str_find_last_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_of(const basic_string& __str, size_type __pos) const _NOEXCEPT {
  return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
      data(), size(), __str.data(), __pos, __str.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_of(const _Tp& __t, size_type __pos) const _NOEXCEPT {
  __self_view __sv = __t;
  return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
      data(), size(), __sv.data(), __pos, __sv.size());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s, size_type __pos) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::find_last_of(): received nullptr");
  return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
      data(), size(), __s, __pos, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_of(value_type __c, size_type __pos) const _NOEXCEPT {
  return rfind(__c, __pos);
}

// find_first_not_of

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(
    const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
  return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(
    const basic_string& __str, size_type __pos) const _NOEXCEPT {
  return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
      data(), size(), __str.data(), __pos, __str.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const _Tp& __t, size_type __pos) const _NOEXCEPT {
  __self_view __sv = __t;
  return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
      data(), size(), __sv.data(), __pos, __sv.size());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s, size_type __pos) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::find_first_not_of(): received nullptr");
  return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
      data(), size(), __s, __pos, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(value_type __c, size_type __pos) const _NOEXCEPT {
  return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}

// find_last_not_of

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(
    const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
  return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(
    const basic_string& __str, size_type __pos) const _NOEXCEPT {
  return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
      data(), size(), __str.data(), __pos, __str.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const _Tp& __t, size_type __pos) const _NOEXCEPT {
  __self_view __sv = __t;
  return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
      data(), size(), __sv.data(), __pos, __sv.size());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s, size_type __pos) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::find_last_not_of(): received nullptr");
  return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
      data(), size(), __s, __pos, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 typename basic_string<_CharT, _Traits, _Allocator>::size_type
basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(value_type __c, size_type __pos) const _NOEXCEPT {
  return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}

// compare

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 int basic_string<_CharT, _Traits, _Allocator>::compare(const _Tp& __t) const _NOEXCEPT {
  __self_view __sv = __t;
  size_t __lhs_sz  = size();
  size_t __rhs_sz  = __sv.size();
  int __result     = traits_type::compare(data(), __sv.data(), std::min(__lhs_sz, __rhs_sz));
  if (__result != 0)
    return __result;
  if (__lhs_sz < __rhs_sz)
    return -1;
  if (__lhs_sz > __rhs_sz)
    return 1;
  return 0;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 int
basic_string<_CharT, _Traits, _Allocator>::compare(const basic_string& __str) const _NOEXCEPT {
  return compare(__self_view(__str));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 int basic_string<_CharT, _Traits, _Allocator>::compare(
    size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const {
  _LIBCPP_ASSERT_NON_NULL(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
  size_type __sz = size();
  if (__pos1 > __sz || __n2 == npos)
    __throw_out_of_range();
  size_type __rlen = std::min(__n1, __sz - __pos1);
  int __r          = traits_type::compare(data() + __pos1, __s, std::min(__rlen, __n2));
  if (__r == 0) {
    if (__rlen < __n2)
      __r = -1;
    else if (__rlen > __n2)
      __r = 1;
  }
  return __r;
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp, __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 int
basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1, size_type __n1, const _Tp& __t) const {
  __self_view __sv = __t;
  return compare(__pos1, __n1, __sv.data(), __sv.size());
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 int
basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1, size_type __n1, const basic_string& __str) const {
  return compare(__pos1, __n1, __str.data(), __str.size());
}

template <class _CharT, class _Traits, class _Allocator>
template <class _Tp,
          __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
                            !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
                        int> >
_LIBCPP_CONSTEXPR_SINCE_CXX20 int basic_string<_CharT, _Traits, _Allocator>::compare(
    size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2) const {
  __self_view __sv = __t;
  return __self_view(*this).substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 int basic_string<_CharT, _Traits, _Allocator>::compare(
    size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2) const {
  return compare(__pos1, __n1, __self_view(__str), __pos2, __n2);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 int
basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::compare(): received nullptr");
  return compare(0, npos, __s, traits_type::length(__s));
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_CONSTEXPR_SINCE_CXX20 int
basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1, size_type __n1, const value_type* __s) const {
  _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string::compare(): received nullptr");
  return compare(__pos1, __n1, __s, traits_type::length(__s));
}

// __invariants

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 bool basic_string<_CharT, _Traits, _Allocator>::__invariants() const {
  if (size() > capacity())
    return false;
  if (capacity() < __min_cap - 1)
    return false;
  if (data() == nullptr)
    return false;
  if (!_Traits::eq(data()[size()], value_type()))
    return false;
  return true;
}

// __clear_and_shrink

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 void basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT {
  clear();
  if (__is_long()) {
    __annotate_delete();
    __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
    __r_.first() = __rep();
  }
}

// operator==

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool
operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
#if _LIBCPP_STD_VER >= 20
  return basic_string_view<_CharT, _Traits>(__lhs) == basic_string_view<_CharT, _Traits>(__rhs);
#else
  size_t __lhs_sz = __lhs.size();
  return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(), __rhs.data(), __lhs_sz) == 0;
#endif
}

template <class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool
operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
           const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT {
  size_t __lhs_sz = __lhs.size();
  if (__lhs_sz != __rhs.size())
    return false;
  const char* __lp = __lhs.data();
  const char* __rp = __rhs.data();
  if (__lhs.__is_long())
    return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
  for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
    if (*__lp != *__rp)
      return false;
  return true;
}

#if _LIBCPP_STD_VER <= 17
template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator==(const _CharT* __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  typedef basic_string<_CharT, _Traits, _Allocator> _String;
  _LIBCPP_ASSERT_NON_NULL(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
  size_t __lhs_len = _Traits::length(__lhs);
  if (__lhs_len != __rhs.size())
    return false;
  return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
}
#endif // _LIBCPP_STD_VER <= 17

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI bool
operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) _NOEXCEPT {
#if _LIBCPP_STD_VER >= 20
  return basic_string_view<_CharT, _Traits>(__lhs) == basic_string_view<_CharT, _Traits>(__rhs);
#else
  typedef basic_string<_CharT, _Traits, _Allocator> _String;
  _LIBCPP_ASSERT_NON_NULL(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
  size_t __rhs_len = _Traits::length(__rhs);
  if (__rhs_len != __lhs.size())
    return false;
  return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
#endif
}

#if _LIBCPP_STD_VER >= 20

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI constexpr auto operator<=>(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
                                                 const basic_string<_CharT, _Traits, _Allocator>& __rhs) noexcept {
  return basic_string_view<_CharT, _Traits>(__lhs) <=> basic_string_view<_CharT, _Traits>(__rhs);
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI constexpr auto
operator<=>(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) {
  return basic_string_view<_CharT, _Traits>(__lhs) <=> basic_string_view<_CharT, _Traits>(__rhs);
}

#else  // _LIBCPP_STD_VER >= 20

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
                                             const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return !(__lhs == __rhs);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator!=(const _CharT* __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return !(__lhs == __rhs);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) _NOEXCEPT {
  return !(__lhs == __rhs);
}

// operator<

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool operator<(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
                                            const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) < 0;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) < 0;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<(const _CharT* __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return __rhs.compare(__lhs) > 0;
}

// operator>

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool operator>(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
                                            const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return __rhs < __lhs;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) _NOEXCEPT {
  return __rhs < __lhs;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>(const _CharT* __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return __rhs < __lhs;
}

// operator<=

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
                                             const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return !(__rhs < __lhs);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) _NOEXCEPT {
  return !(__rhs < __lhs);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator<=(const _CharT* __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return !(__rhs < __lhs);
}

// operator>=

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
                                             const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return !(__lhs < __rhs);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) _NOEXCEPT {
  return !(__lhs < __rhs);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI bool
operator>=(const _CharT* __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT {
  return !(__lhs < __rhs);
}
#endif // _LIBCPP_STD_VER >= 20

// operator +

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
          const basic_string<_CharT, _Traits, _Allocator>& __rhs) {
  using _String = basic_string<_CharT, _Traits, _Allocator>;
  auto __lhs_sz = __lhs.size();
  auto __rhs_sz = __rhs.size();
  _String __r(__uninitialized_size_tag(),
              __lhs_sz + __rhs_sz,
              _String::__alloc_traits::select_on_container_copy_construction(__lhs.get_allocator()));
  auto __ptr = std::__to_address(__r.__get_pointer());
  _Traits::copy(__ptr, __lhs.data(), __lhs_sz);
  _Traits::copy(__ptr + __lhs_sz, __rhs.data(), __rhs_sz);
  _Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
  return __r;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDDEN _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const _CharT* __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) {
  using _String = basic_string<_CharT, _Traits, _Allocator>;
  auto __lhs_sz = _Traits::length(__lhs);
  auto __rhs_sz = __rhs.size();
  _String __r(__uninitialized_size_tag(),
              __lhs_sz + __rhs_sz,
              _String::__alloc_traits::select_on_container_copy_construction(__rhs.get_allocator()));
  auto __ptr = std::__to_address(__r.__get_pointer());
  _Traits::copy(__ptr, __lhs, __lhs_sz);
  _Traits::copy(__ptr + __lhs_sz, __rhs.data(), __rhs_sz);
  _Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
  return __r;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(_CharT __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) {
  using _String                        = basic_string<_CharT, _Traits, _Allocator>;
  typename _String::size_type __rhs_sz = __rhs.size();
  _String __r(__uninitialized_size_tag(),
              __rhs_sz + 1,
              _String::__alloc_traits::select_on_container_copy_construction(__rhs.get_allocator()));
  auto __ptr = std::__to_address(__r.__get_pointer());
  _Traits::assign(__ptr, 1, __lhs);
  _Traits::copy(__ptr + 1, __rhs.data(), __rhs_sz);
  _Traits::assign(__ptr + 1 + __rhs_sz, 1, _CharT());
  return __r;
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs) {
  using _String                        = basic_string<_CharT, _Traits, _Allocator>;
  typename _String::size_type __lhs_sz = __lhs.size();
  typename _String::size_type __rhs_sz = _Traits::length(__rhs);
  _String __r(__uninitialized_size_tag(),
              __lhs_sz + __rhs_sz,
              _String::__alloc_traits::select_on_container_copy_construction(__lhs.get_allocator()));
  auto __ptr = std::__to_address(__r.__get_pointer());
  _Traits::copy(__ptr, __lhs.data(), __lhs_sz);
  _Traits::copy(__ptr + __lhs_sz, __rhs, __rhs_sz);
  _Traits::assign(__ptr + __lhs_sz + __rhs_sz, 1, _CharT());
  return __r;
}

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs) {
  using _String                        = basic_string<_CharT, _Traits, _Allocator>;
  typename _String::size_type __lhs_sz = __lhs.size();
  _String __r(__uninitialized_size_tag(),
              __lhs_sz + 1,
              _String::__alloc_traits::select_on_container_copy_construction(__lhs.get_allocator()));
  auto __ptr = std::__to_address(__r.__get_pointer());
  _Traits::copy(__ptr, __lhs.data(), __lhs_sz);
  _Traits::assign(__ptr + __lhs_sz, 1, __rhs);
  _Traits::assign(__ptr + 1 + __lhs_sz, 1, _CharT());
  return __r;
}

#ifndef _LIBCPP_CXX03_LANG

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs) {
  return std::move(__lhs.append(__rhs));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs) {
  return std::move(__rhs.insert(0, __lhs));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs) {
  return std::move(__lhs.append(__rhs));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(const _CharT* __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs) {
  return std::move(__rhs.insert(0, __lhs));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(_CharT __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs) {
  __rhs.insert(__rhs.begin(), __lhs);
  return std::move(__rhs);
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs) {
  return std::move(__lhs.append(__rhs));
}

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<_CharT, _Traits, _Allocator>
operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs) {
  __lhs.push_back(__rhs);
  return std::move(__lhs);
}

#endif // _LIBCPP_CXX03_LANG

// swap

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void
swap(basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>& __rhs)
    _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs))) {
  __lhs.swap(__rhs);
}

_LIBCPP_EXPORTED_FROM_ABI int stoi(const string& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI long stol(const string& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI unsigned long stoul(const string& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI long long stoll(const string& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI unsigned long long stoull(const string& __str, size_t* __idx = nullptr, int __base = 10);

_LIBCPP_EXPORTED_FROM_ABI float stof(const string& __str, size_t* __idx = nullptr);
_LIBCPP_EXPORTED_FROM_ABI double stod(const string& __str, size_t* __idx = nullptr);
_LIBCPP_EXPORTED_FROM_ABI long double stold(const string& __str, size_t* __idx = nullptr);

_LIBCPP_EXPORTED_FROM_ABI string to_string(int __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(unsigned __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(long __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(unsigned long __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(long long __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(unsigned long long __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(float __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(double __val);
_LIBCPP_EXPORTED_FROM_ABI string to_string(long double __val);

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
_LIBCPP_EXPORTED_FROM_ABI int stoi(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI long stol(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI unsigned long stoul(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI long long stoll(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
_LIBCPP_EXPORTED_FROM_ABI unsigned long long stoull(const wstring& __str, size_t* __idx = nullptr, int __base = 10);

_LIBCPP_EXPORTED_FROM_ABI float stof(const wstring& __str, size_t* __idx = nullptr);
_LIBCPP_EXPORTED_FROM_ABI double stod(const wstring& __str, size_t* __idx = nullptr);
_LIBCPP_EXPORTED_FROM_ABI long double stold(const wstring& __str, size_t* __idx = nullptr);

_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(int __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(unsigned __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(long __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(unsigned long __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(long long __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(unsigned long long __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(float __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(double __val);
_LIBCPP_EXPORTED_FROM_ABI wstring to_wstring(long double __val);
#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_TEMPLATE_DATA_VIS const typename basic_string<_CharT, _Traits, _Allocator>::size_type
    basic_string<_CharT, _Traits, _Allocator>::npos;

template <class _CharT, class _Allocator>
struct __string_hash : public __unary_function<basic_string<_CharT, char_traits<_CharT>, _Allocator>, size_t> {
  _LIBCPP_HIDE_FROM_ABI size_t
  operator()(const basic_string<_CharT, char_traits<_CharT>, _Allocator>& __val) const _NOEXCEPT {
    return std::__do_string_hash(__val.data(), __val.data() + __val.size());
  }
};

template <class _Allocator>
struct hash<basic_string<char, char_traits<char>, _Allocator> > : __string_hash<char, _Allocator> {};

#ifndef _LIBCPP_HAS_NO_CHAR8_T
template <class _Allocator>
struct hash<basic_string<char8_t, char_traits<char8_t>, _Allocator> > : __string_hash<char8_t, _Allocator> {};
#endif

template <class _Allocator>
struct hash<basic_string<char16_t, char_traits<char16_t>, _Allocator> > : __string_hash<char16_t, _Allocator> {};

template <class _Allocator>
struct hash<basic_string<char32_t, char_traits<char32_t>, _Allocator> > : __string_hash<char32_t, _Allocator> {};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <class _Allocator>
struct hash<basic_string<wchar_t, char_traits<wchar_t>, _Allocator> > : __string_hash<wchar_t, _Allocator> {};
#endif

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const basic_string<_CharT, _Traits, _Allocator>& __str);

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
operator>>(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _Allocator>& __str);

template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
getline(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
getline(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _Allocator>& __str);

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
getline(basic_istream<_CharT, _Traits>&& __is, basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);

template <class _CharT, class _Traits, class _Allocator>
inline _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
getline(basic_istream<_CharT, _Traits>&& __is, basic_string<_CharT, _Traits, _Allocator>& __str);

#if _LIBCPP_STD_VER >= 20
template <class _CharT, class _Traits, class _Allocator, class _Up>
inline _LIBCPP_HIDE_FROM_ABI typename basic_string<_CharT, _Traits, _Allocator>::size_type
erase(basic_string<_CharT, _Traits, _Allocator>& __str, const _Up& __v) {
  auto __old_size = __str.size();
  __str.erase(std::remove(__str.begin(), __str.end(), __v), __str.end());
  return __old_size - __str.size();
}

template <class _CharT, class _Traits, class _Allocator, class _Predicate>
inline _LIBCPP_HIDE_FROM_ABI typename basic_string<_CharT, _Traits, _Allocator>::size_type
erase_if(basic_string<_CharT, _Traits, _Allocator>& __str, _Predicate __pred) {
  auto __old_size = __str.size();
  __str.erase(std::remove_if(__str.begin(), __str.end(), __pred), __str.end());
  return __old_size - __str.size();
}
#endif

#if _LIBCPP_STD_VER >= 14
// Literal suffixes for basic_string [basic.string.literals]
inline namespace literals {
inline namespace string_literals {
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<char>
operator""s(const char* __str, size_t __len) {
  return basic_string<char>(__str, __len);
}

#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<wchar_t>
operator""s(const wchar_t* __str, size_t __len) {
  return basic_string<wchar_t>(__str, __len);
}
#  endif

#  ifndef _LIBCPP_HAS_NO_CHAR8_T
inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string<char8_t> operator""s(const char8_t* __str, size_t __len) {
  return basic_string<char8_t>(__str, __len);
}
#  endif

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<char16_t>
operator""s(const char16_t* __str, size_t __len) {
  return basic_string<char16_t>(__str, __len);
}

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 basic_string<char32_t>
operator""s(const char32_t* __str, size_t __len) {
  return basic_string<char32_t>(__str, __len);
}
} // namespace string_literals
} // namespace literals

#  if _LIBCPP_STD_VER >= 20
template <>
inline constexpr bool __format::__enable_insertable<std::basic_string<char>> = true;
#    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
inline constexpr bool __format::__enable_insertable<std::basic_string<wchar_t>> = true;
#    endif
#  endif

#endif

_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
#  include <algorithm>
#  include <concepts>
#  include <cstdlib>
#  include <iterator>
#  include <new>
#  include <type_traits>
#  include <typeinfo>
#  include <utility>
#endif

#endif // _LIBCPP_STRING