Proposed package to replace iphoneos-sys.

1 files changed, 4076 insertions, 0 deletions

diff --git a/data/iphoneos-sdk/v1/string b/data/iphoneos-sdk/v1/string
new file mode 100755
index 000000000..f5d548965
--- /dev/null
+++ b/data/iphoneos-sdk/v1/string
@@ -0,0 +1,4076 @@
+// -*- C++ -*-
+//===--------------------------- string -----------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_STRING
+#define _LIBCPP_STRING
+
+/*
+    string synopsis
+
+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
+{
+    typedef charT     char_type;
+    typedef ...       int_type;
+    typedef streamoff off_type;
+    typedef streampos pos_type;
+    typedef mbstate_t state_type;
+
+    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<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);
+    explicit basic_string(const allocator_type& a);
+    basic_string(const basic_string& str);
+    basic_string(basic_string&& str)
+        noexcept(is_nothrow_move_constructible<allocator_type>::value);
+    basic_string(const basic_string& str, size_type pos,
+                 const allocator_type& a = allocator_type());
+    basic_string(const basic_string& str, size_type pos, size_type n,
+                 const Allocator& a = Allocator());
+    template<class T>
+        basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator()); // C++17
+    explicit basic_string(const basic_string_view<charT, traits> sv, const Allocator& a = Allocator());
+    basic_string(const value_type* s, const allocator_type& a = allocator_type());
+    basic_string(const value_type* s, size_type n, const allocator_type& a = allocator_type());
+    basic_string(size_type n, value_type c, const allocator_type& a = allocator_type());
+    template<class InputIterator>
+        basic_string(InputIterator begin, InputIterator end,
+                     const allocator_type& a = allocator_type());
+    basic_string(initializer_list<value_type>, const Allocator& = Allocator());
+    basic_string(const basic_string&, const Allocator&);
+    basic_string(basic_string&&, const Allocator&);
+
+    ~basic_string();
+
+    operator basic_string_view<charT, traits>() const noexcept;
+
+    basic_string& operator=(const basic_string& str);
+    basic_string& operator=(basic_string_view<charT, traits> sv);
+    basic_string& operator=(basic_string&& str)
+        noexcept(
+             allocator_type::propagate_on_container_move_assignment::value ||
+             allocator_type::is_always_equal::value ); // C++17
+    basic_string& operator=(const value_type* s);
+    basic_string& operator=(value_type c);
+    basic_string& operator=(initializer_list<value_type>);
+
+    iterator       begin() noexcept;
+    const_iterator begin() const noexcept;
+    iterator       end() noexcept;
+    const_iterator end() const noexcept;
+
+    reverse_iterator       rbegin() noexcept;
+    const_reverse_iterator rbegin() const noexcept;
+    reverse_iterator       rend() noexcept;
+    const_reverse_iterator rend() const noexcept;
+
+    const_iterator         cbegin() const noexcept;
+    const_iterator         cend() const noexcept;
+    const_reverse_iterator crbegin() const noexcept;
+    const_reverse_iterator crend() const noexcept;
+
+    size_type size() const noexcept;
+    size_type length() const noexcept;
+    size_type max_size() const noexcept;
+    size_type capacity() const noexcept;
+
+    void resize(size_type n, value_type c);
+    void resize(size_type n);
+
+    void reserve(size_type res_arg = 0);
+    void shrink_to_fit();
+    void clear() noexcept;
+    bool empty() const noexcept;
+
+    const_reference operator[](size_type pos) const;
+    reference       operator[](size_type pos);
+
+    const_reference at(size_type n) const;
+    reference       at(size_type n);
+
+    basic_string& operator+=(const basic_string& str);
+    basic_string& operator+=(basic_string_view<charT, traits> sv);
+    basic_string& operator+=(const value_type* s);
+    basic_string& operator+=(value_type c);
+    basic_string& operator+=(initializer_list<value_type>);
+
+    basic_string& append(const basic_string& str);
+    basic_string& append(basic_string_view<charT, traits> sv);
+    basic_string& append(const basic_string& str, size_type pos, size_type n=npos); //C++14
+    template <class T>
+        basic_string& append(const T& t, size_type pos, size_type n=npos); // C++17
+    basic_string& append(const value_type* s, size_type n);
+    basic_string& append(const value_type* s);
+    basic_string& append(size_type n, value_type c);
+    template<class InputIterator>
+        basic_string& append(InputIterator first, InputIterator last);
+    basic_string& append(initializer_list<value_type>);
+
+    void push_back(value_type c);
+    void pop_back();
+    reference       front();
+    const_reference front() const;
+    reference       back();
+    const_reference back() const;
+
+    basic_string& assign(const basic_string& str);
+    basic_string& assign(basic_string_view<charT, traits> sv);
+    basic_string& assign(basic_string&& str);
+    basic_string& assign(const basic_string& str, size_type pos, size_type n=npos); // C++14
+    template <class T>
+        basic_string& assign(const T& t, size_type pos, size_type n=npos); // C++17
+    basic_string& assign(const value_type* s, size_type n);
+    basic_string& assign(const value_type* s);
+    basic_string& assign(size_type n, value_type c);
+    template<class InputIterator>
+        basic_string& assign(InputIterator first, InputIterator last);
+    basic_string& assign(initializer_list<value_type>);
+
+    basic_string& insert(size_type pos1, const basic_string& str);
+    basic_string& insert(size_type pos1, basic_string_view<charT, traits> sv);
+    basic_string& insert(size_type pos1, const basic_string& str,
+                         size_type pos2, size_type n);
+    template <class T>
+        basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17
+    basic_string& insert(size_type pos, const value_type* s, size_type n=npos); //C++14
+    basic_string& insert(size_type pos, const value_type* s);
+    basic_string& insert(size_type pos, size_type n, value_type c);
+    iterator      insert(const_iterator p, value_type c);
+    iterator      insert(const_iterator p, size_type n, value_type c);
+    template<class InputIterator>
+        iterator insert(const_iterator p, InputIterator first, InputIterator last);
+    iterator      insert(const_iterator p, initializer_list<value_type>);
+
+    basic_string& erase(size_type pos = 0, size_type n = npos);
+    iterator      erase(const_iterator position);
+    iterator      erase(const_iterator first, const_iterator last);
+
+    basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
+    basic_string& replace(size_type pos1, size_type n1, basic_string_view<charT, traits> sv);
+    basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
+                          size_type pos2, size_type n2=npos); // C++14
+    template <class T>
+        basic_string& replace(size_type pos1, size_type n1, const T& t,
+                              size_type pos2, size_type n); // C++17
+    basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2);
+    basic_string& replace(size_type pos, size_type n1, const value_type* s);
+    basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c);
+    basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);
+    basic_string& replace(const_iterator i1, const_iterator i2, basic_string_view<charT, traits> sv);
+    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s, size_type n);
+    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s);
+    basic_string& replace(const_iterator i1, const_iterator i2, size_type n, value_type c);
+    template<class InputIterator>
+        basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2);
+    basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<value_type>);
+
+    size_type copy(value_type* s, size_type n, size_type pos = 0) const;
+    basic_string substr(size_type pos = 0, size_type n = npos) const;
+
+    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
+
+    const value_type* c_str() const noexcept;
+    const value_type* data() const noexcept;
+          value_type* data()       noexcept;   // C++17
+
+    allocator_type get_allocator() const noexcept;
+
+    size_type find(const basic_string& str, size_type pos = 0) const noexcept;
+    size_type find(basic_string_view<charT, traits> sv, size_type pos = 0) const noexcept;
+    size_type find(const value_type* s, size_type pos, size_type n) const noexcept;
+    size_type find(const value_type* s, size_type pos = 0) const noexcept;
+    size_type find(value_type c, size_type pos = 0) const noexcept;
+
+    size_type rfind(const basic_string& str, size_type pos = npos) const noexcept;
+    size_type rfind(basic_string_view<charT, traits> sv, size_type pos = npos) const noexcept;
+    size_type rfind(const value_type* s, size_type pos, size_type n) const noexcept;
+    size_type rfind(const value_type* s, size_type pos = npos) const noexcept;
+    size_type rfind(value_type c, size_type pos = npos) const noexcept;
+
+    size_type find_first_of(const basic_string& str, size_type pos = 0) const noexcept;
+    size_type find_first_of(basic_string_view<charT, traits> sv, size_type pos = 0) const noexcept;
+    size_type find_first_of(const value_type* s, size_type pos, size_type n) const noexcept;
+    size_type find_first_of(const value_type* s, size_type pos = 0) const noexcept;
+    size_type find_first_of(value_type c, size_type pos = 0) const noexcept;
+
+    size_type find_last_of(const basic_string& str, size_type pos = npos) const noexcept;
+    size_type find_last_of(basic_string_view<charT, traits> sv, size_type pos = npos) const noexcept;
+    size_type find_last_of(const value_type* s, size_type pos, size_type n) const noexcept;
+    size_type find_last_of(const value_type* s, size_type pos = npos) const noexcept;
+    size_type find_last_of(value_type c, size_type pos = npos) const noexcept;
+
+    size_type find_first_not_of(const basic_string& str, size_type pos = 0) const noexcept;
+    size_type find_first_not_of(basic_string_view<charT, traits> sv, size_type pos = 0) const noexcept;
+    size_type find_first_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
+    size_type find_first_not_of(const value_type* s, size_type pos = 0) const noexcept;
+    size_type find_first_not_of(value_type c, size_type pos = 0) const noexcept;
+
+    size_type find_last_not_of(const basic_string& str, size_type pos = npos) const noexcept;
+    size_type find_last_not_of(basic_string_view<charT, traits> sv, size_type pos = npos) const noexcept;
+    size_type find_last_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
+    size_type find_last_not_of(const value_type* s, size_type pos = npos) const noexcept;
+    size_type find_last_not_of(value_type c, size_type pos = npos) const noexcept;
+
+    int compare(const basic_string& str) const noexcept;
+    int compare(basic_string_view<charT, traits> sv) const noexcept;
+    int compare(size_type pos1, size_type n1, const basic_string& str) const;
+    int compare(size_type pos1, size_type n1, basic_string_view<charT, traits> sv) const;
+    int compare(size_type pos1, size_type n1, const basic_string& str,
+                size_type pos2, size_type n2=npos) const; // C++14
+    template <class T>
+        int compare(size_type pos1, size_type n1, const T& t,
+                    size_type pos2, size_type n2=npos) const; // C++17
+    int compare(const value_type* s) const noexcept;
+    int compare(size_type pos1, size_type n1, const value_type* s) const;
+    int compare(size_type pos1, size_type n1, const value_type* s, size_type n2) const;
+
+    bool starts_with(basic_string_view<charT, traits> sv) const noexcept; // C++2a
+    bool starts_with(charT c) const noexcept;                             // C++2a
+    bool starts_with(const charT* s) const;                               // C++2a
+    bool ends_with(basic_string_view<charT, traits> sv) const noexcept;   // C++2a
+    bool ends_with(charT c) const noexcept;                               // C++2a
+    bool ends_with(const charT* s) const;                                 // C++2a
+
+    bool __invariants() const;
+};
+
+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);
+
+template<class charT, class traits, class Allocator>
+basic_string<charT, traits, Allocator>
+operator+(const charT* lhs , const basic_string<charT,traits,Allocator>&rhs);
+
+template<class charT, class traits, class Allocator>
+basic_string<charT, traits, Allocator>
+operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);
+
+template<class charT, class traits, class Allocator>
+basic_string<charT, traits, Allocator>
+operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
+
+template<class charT, class traits, class Allocator>
+basic_string<charT, traits, Allocator>
+operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
+
+template<class charT, class traits, class Allocator>
+bool operator==(const basic_string<charT, traits, Allocator>& lhs,
+                const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator==(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
+                const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator!=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator!=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator< (const basic_string<charT, traits, Allocator>& lhs,
+                const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator< (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator< (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator> (const basic_string<charT, traits, Allocator>& lhs,
+                const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator> (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator> (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator<=(const basic_string<charT, traits, Allocator>& lhs,
+                const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator<=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator<=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator>=(const basic_string<charT, traits, Allocator>& lhs,
+                const basic_string<charT, traits, Allocator>& rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator>=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
+
+template<class charT, class traits, class Allocator>
+bool operator>=(const charT* lhs, const basic_string<charT, traits, Allocator>& 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)));
+
+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);
+
+typedef basic_string<char>    string;
+typedef basic_string<wchar_t> wstring;
+typedef basic_string<char16_t> u16string;
+typedef basic_string<char32_t> u32string;
+
+int                stoi  (const string& str, size_t* idx = 0, int base = 10);
+long               stol  (const string& str, size_t* idx = 0, int base = 10);
+unsigned long      stoul (const string& str, size_t* idx = 0, int base = 10);
+long long          stoll (const string& str, size_t* idx = 0, int base = 10);
+unsigned long long stoull(const string& str, size_t* idx = 0, int base = 10);
+
+float       stof (const string& str, size_t* idx = 0);
+double      stod (const string& str, size_t* idx = 0);
+long double stold(const string& str, size_t* idx = 0);
+
+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 = 0, int base = 10);
+long               stol  (const wstring& str, size_t* idx = 0, int base = 10);
+unsigned long      stoul (const wstring& str, size_t* idx = 0, int base = 10);
+long long          stoll (const wstring& str, size_t* idx = 0, int base = 10);
+unsigned long long stoull(const wstring& str, size_t* idx = 0, int base = 10);
+
+float       stof (const wstring& str, size_t* idx = 0);
+double      stod (const wstring& str, size_t* idx = 0);
+long double stold(const wstring& str, size_t* idx = 0);
+
+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<u16string>;
+template <> struct hash<u32string>;
+template <> struct hash<wstring>;
+
+basic_string<char>     operator "" s( const char *str,     size_t len ); // C++14
+basic_string<wchar_t>  operator "" s( const wchar_t *str,  size_t len ); // C++14
+basic_string<char16_t> operator "" s( const char16_t *str, size_t len ); // C++14
+basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++14
+
+}  // std
+
+*/
+
+#include <__config>
+#include <string_view>
+#include <iosfwd>
+#include <cstring>
+#include <cstdio>  // For EOF.
+#include <cwchar>
+#include <algorithm>
+#include <iterator>
+#include <utility>
+#include <memory>
+#include <stdexcept>
+#include <type_traits>
+#include <initializer_list>
+#include <__functional_base>
+#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
+#include <cstdint>
+#endif
+
+#include <__debug>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// fpos
+
+template <class _StateT>
+class _LIBCPP_TEMPLATE_VIS fpos
+{
+private:
+    _StateT __st_;
+    streamoff __off_;
+public:
+    _LIBCPP_INLINE_VISIBILITY fpos(streamoff __off = streamoff()) : __st_(), __off_(__off) {}
+
+    _LIBCPP_INLINE_VISIBILITY operator streamoff() const {return __off_;}
+
+    _LIBCPP_INLINE_VISIBILITY _StateT state() const {return __st_;}
+    _LIBCPP_INLINE_VISIBILITY void state(_StateT __st) {__st_ = __st;}
+
+    _LIBCPP_INLINE_VISIBILITY fpos& operator+=(streamoff __off) {__off_ += __off; return *this;}
+    _LIBCPP_INLINE_VISIBILITY fpos  operator+ (streamoff __off) const {fpos __t(*this); __t += __off; return __t;}
+    _LIBCPP_INLINE_VISIBILITY fpos& operator-=(streamoff __off) {__off_ -= __off; return *this;}
+    _LIBCPP_INLINE_VISIBILITY fpos  operator- (streamoff __off) const {fpos __t(*this); __t -= __off; return __t;}
+};
+
+template <class _StateT>
+inline _LIBCPP_INLINE_VISIBILITY
+streamoff operator-(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
+    {return streamoff(__x) - streamoff(__y);}
+
+template <class _StateT>
+inline _LIBCPP_INLINE_VISIBILITY
+bool operator==(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
+    {return streamoff(__x) == streamoff(__y);}
+
+template <class _StateT>
+inline _LIBCPP_INLINE_VISIBILITY
+bool operator!=(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
+    {return streamoff(__x) != streamoff(__y);}
+
+// basic_string
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const basic_string<_CharT, _Traits, _Allocator>& __x,
+          const basic_string<_CharT, _Traits, _Allocator>& __y);
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const _CharT* __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(_CharT __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, const _CharT* __y);
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, _CharT __y);
+
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS string operator+<char, char_traits<char>, allocator<char> >(char const*, string const&))
+
+template <bool>
+class _LIBCPP_TEMPLATE_VIS __basic_string_common
+{
+protected:
+    _LIBCPP_NORETURN void __throw_length_error() const;
+    _LIBCPP_NORETURN void __throw_out_of_range() const;
+};
+
+template <bool __b>
+void
+__basic_string_common<__b>::__throw_length_error() const
+{
+    _VSTD::__throw_length_error("basic_string");
+}
+
+template <bool __b>
+void
+__basic_string_common<__b>::__throw_out_of_range() const
+{
+    _VSTD::__throw_out_of_range("basic_string");
+}
+
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS __basic_string_common<true>)
+
+#ifdef _LIBCPP_NO_EXCEPTIONS
+template <class _Iter>
+struct __libcpp_string_gets_noexcept_iterator_impl : public true_type {};
+#elif defined(_LIBCPP_HAS_NO_NOEXCEPT)
+template <class _Iter>
+struct __libcpp_string_gets_noexcept_iterator_impl : public false_type {};
+#else
+template <class _Iter, bool = __is_forward_iterator<_Iter>::value>
+struct __libcpp_string_gets_noexcept_iterator_impl : public _LIBCPP_BOOL_CONSTANT((
+    noexcept(++(declval<_Iter&>())) && 
+    is_nothrow_assignable<_Iter&, _Iter>::value && 
+    noexcept(declval<_Iter>() == declval<_Iter>()) && 
+    noexcept(*declval<_Iter>())
+)) {};
+
+template <class _Iter> 
+struct __libcpp_string_gets_noexcept_iterator_impl<_Iter, false> : public false_type {};
+#endif
+
+
+template <class _Iter>
+struct __libcpp_string_gets_noexcept_iterator
+    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value || __libcpp_string_gets_noexcept_iterator_impl<_Iter>::value) {};
+
+template <class _CharT, class _Traits, class _Tp>
+struct __can_be_converted_to_string_view : public _LIBCPP_BOOL_CONSTANT(
+    ( is_convertible<const _Tp&, basic_string_view<_CharT, _Traits> >::value &&
+     !is_convertible<const _Tp&, const _CharT*>::value)) {};
+
+#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+
+template <class _CharT, size_t = sizeof(_CharT)>
+struct __padding
+{
+    unsigned char __xx[sizeof(_CharT)-1];
+};
+
+template <class _CharT>
+struct __padding<_CharT, 1>
+{
+};
+
+#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+
+template<class _CharT, class _Traits, class _Allocator>
+class _LIBCPP_TEMPLATE_VIS basic_string
+    : private __basic_string_common<true>
+{
+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_pod<value_type>::value, "Character type of basic_string must be a POD");
+    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");
+#if defined(_LIBCPP_RAW_ITERATORS)
+    typedef pointer                                      iterator;
+    typedef const_pointer                                const_iterator;
+#else  // defined(_LIBCPP_RAW_ITERATORS)
+    typedef __wrap_iter<pointer>                         iterator;
+    typedef __wrap_iter<const_pointer>                   const_iterator;
+#endif  // defined(_LIBCPP_RAW_ITERATORS)
+    typedef _VSTD::reverse_iterator<iterator>             reverse_iterator;
+    typedef _VSTD::reverse_iterator<const_iterator>       const_reverse_iterator;
+
+private:
+
+#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+
+    struct __long
+    {
+        pointer   __data_;
+        size_type __size_;
+        size_type __cap_;
+    };
+
+#ifdef _LIBCPP_BIG_ENDIAN
+    static const size_type __short_mask = 0x01;
+    static const size_type __long_mask  = 0x1ul;
+#else  // _LIBCPP_BIG_ENDIAN
+    static const size_type __short_mask = 0x80;
+    static const size_type __long_mask  = ~(size_type(~0) >> 1);
+#endif  // _LIBCPP_BIG_ENDIAN
+
+    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
+                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
+
+    struct __short
+    {
+        value_type __data_[__min_cap];
+        struct
+            : __padding<value_type>
+        {
+            unsigned char __size_;
+        };
+    };
+
+#else
+
+    struct __long
+    {
+        size_type __cap_;
+        size_type __size_;
+        pointer   __data_;
+    };
+
+#ifdef _LIBCPP_BIG_ENDIAN
+    static const size_type __short_mask = 0x80;
+    static const size_type __long_mask  = ~(size_type(~0) >> 1);
+#else  // _LIBCPP_BIG_ENDIAN
+    static const size_type __short_mask = 0x01;
+    static const size_type __long_mask  = 0x1ul;
+#endif  // _LIBCPP_BIG_ENDIAN
+
+    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
+                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
+
+    struct __short
+    {
+        union
+        {
+            unsigned char __size_;
+            value_type __lx;
+        };
+        value_type __data_[__min_cap];
+    };
+
+#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+
+    union __ulx{__long __lx; __short __lxx;};
+
+    enum {__n_words = sizeof(__ulx) / sizeof(size_type)};
+
+    struct __raw
+    {
+        size_type __words[__n_words];
+    };
+
+    struct __rep
+    {
+        union
+        {
+            __long  __l;
+            __short __s;
+            __raw   __r;
+        };
+    };
+
+    __compressed_pair<__rep, allocator_type> __r_;
+
+public:
+    static const size_type npos = -1;
+
+    _LIBCPP_INLINE_VISIBILITY basic_string()
+        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
+
+    _LIBCPP_INLINE_VISIBILITY explicit basic_string(const allocator_type& __a)
+#if _LIBCPP_STD_VER <= 14
+        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value);
+#else
+        _NOEXCEPT;
+#endif
+
+    basic_string(const basic_string& __str);
+    basic_string(const basic_string& __str, const allocator_type& __a);
+
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(basic_string&& __str)
+#if _LIBCPP_STD_VER <= 14
+        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
+#else
+        _NOEXCEPT;
+#endif
+
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(basic_string&& __str, const allocator_type& __a);
+#endif  // _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY basic_string(const _CharT* __s);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(const _CharT* __s, const _Allocator& __a);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(const _CharT* __s, size_type __n);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(const _CharT* __s, size_type __n, const _Allocator& __a);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(size_type __n, _CharT __c);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(size_type __n, _CharT __c, const _Allocator& __a);
+    basic_string(const basic_string& __str, size_type __pos, size_type __n,
+                 const _Allocator& __a = _Allocator());
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(const basic_string& __str, size_type __pos,
+                 const _Allocator& __a = _Allocator());
+    template<class _Tp>
+        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+        basic_string(const _Tp& __t, size_type __pos, size_type __n,
+                     const allocator_type& __a = allocator_type(),
+                     typename enable_if<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, void>::type* = 0);
+    _LIBCPP_INLINE_VISIBILITY explicit
+    basic_string(__self_view __sv);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(__self_view __sv, const _Allocator& __a);
+    template<class _InputIterator>
+        _LIBCPP_INLINE_VISIBILITY
+        basic_string(_InputIterator __first, _InputIterator __last);
+    template<class _InputIterator>
+        _LIBCPP_INLINE_VISIBILITY
+        basic_string(_InputIterator __first, _InputIterator __last, const allocator_type& __a);
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(initializer_list<_CharT> __il);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string(initializer_list<_CharT> __il, const _Allocator& __a);
+#endif  // _LIBCPP_CXX03_LANG
+
+    inline ~basic_string();
+
+    _LIBCPP_INLINE_VISIBILITY
+    operator __self_view() const _NOEXCEPT { return __self_view(data(), size()); }
+
+    basic_string& operator=(const basic_string& __str);
+
+#ifndef _LIBCPP_CXX03_LANG
+    template <class = void>
+#endif
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& operator=(__self_view __sv)  {return assign(__sv);}
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& operator=(basic_string&& __str)
+        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value));
+     _LIBCPP_INLINE_VISIBILITY
+    basic_string& operator=(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
+#endif
+    _LIBCPP_INLINE_VISIBILITY basic_string& operator=(const value_type* __s) {return assign(__s);}
+    basic_string& operator=(value_type __c);
+
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    _LIBCPP_INLINE_VISIBILITY
+    iterator begin() _NOEXCEPT
+        {return iterator(this, __get_pointer());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator begin() const _NOEXCEPT
+        {return const_iterator(this, __get_pointer());}
+    _LIBCPP_INLINE_VISIBILITY
+    iterator end() _NOEXCEPT
+        {return iterator(this, __get_pointer() + size());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator end() const _NOEXCEPT
+        {return const_iterator(this, __get_pointer() + size());}
+#else
+    _LIBCPP_INLINE_VISIBILITY
+    iterator begin() _NOEXCEPT
+        {return iterator(__get_pointer());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator begin() const _NOEXCEPT
+        {return const_iterator(__get_pointer());}
+    _LIBCPP_INLINE_VISIBILITY
+    iterator end() _NOEXCEPT
+        {return iterator(__get_pointer() + size());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator end() const _NOEXCEPT
+        {return const_iterator(__get_pointer() + size());}
+#endif  // _LIBCPP_DEBUG_LEVEL >= 2
+    _LIBCPP_INLINE_VISIBILITY
+    reverse_iterator rbegin() _NOEXCEPT
+        {return reverse_iterator(end());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator rbegin() const _NOEXCEPT
+        {return const_reverse_iterator(end());}
+    _LIBCPP_INLINE_VISIBILITY
+    reverse_iterator rend() _NOEXCEPT
+        {return reverse_iterator(begin());}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator rend() const _NOEXCEPT
+        {return const_reverse_iterator(begin());}
+
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator cbegin() const _NOEXCEPT
+        {return begin();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_iterator cend() const _NOEXCEPT
+        {return end();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator crbegin() const _NOEXCEPT
+        {return rbegin();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_reverse_iterator crend() const _NOEXCEPT
+        {return rend();}
+
+    _LIBCPP_INLINE_VISIBILITY size_type size() const _NOEXCEPT
+        {return __is_long() ? __get_long_size() : __get_short_size();}
+    _LIBCPP_INLINE_VISIBILITY size_type length() const _NOEXCEPT {return size();}
+    _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY size_type capacity() const _NOEXCEPT
+        {return (__is_long() ? __get_long_cap()
+                             : static_cast<size_type>(__min_cap)) - 1;}
+
+    void resize(size_type __n, value_type __c);
+    _LIBCPP_INLINE_VISIBILITY void resize(size_type __n) {resize(__n, value_type());}
+
+    void reserve(size_type __res_arg = 0);
+    _LIBCPP_INLINE_VISIBILITY
+    void shrink_to_fit() _NOEXCEPT {reserve();}
+    _LIBCPP_INLINE_VISIBILITY
+    void clear() _NOEXCEPT;
+    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
+    bool empty() const _NOEXCEPT {return size() == 0;}
+
+    _LIBCPP_INLINE_VISIBILITY const_reference operator[](size_type __pos) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY reference       operator[](size_type __pos)       _NOEXCEPT;
+
+    const_reference at(size_type __n) const;
+    reference       at(size_type __n);
+
+    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const basic_string& __str) {return append(__str);}
+    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(__self_view __sv)          {return append(__sv);}
+    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const value_type* __s)     {return append(__s);}
+    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(value_type __c)            {push_back(__c); return *this;}
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(initializer_list<value_type> __il) {return append(__il);}
+#endif  // _LIBCPP_CXX03_LANG
+
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& append(const basic_string& __str);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& append(__self_view __sv) { return append(__sv.data(), __sv.size()); }
+    basic_string& append(const basic_string& __str, size_type __pos, size_type __n=npos);
+    template <class _Tp>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+            basic_string&
+        >::type
+                  append(const _Tp& __t, size_type __pos, size_type __n=npos);
+    basic_string& append(const value_type* __s, size_type __n);
+    basic_string& append(const value_type* __s);
+    basic_string& append(size_type __n, value_type __c);
+    template <class _ForwardIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    basic_string& __append_forward_unsafe(_ForwardIterator, _ForwardIterator);
+    template<class _InputIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __is_exactly_input_iterator<_InputIterator>::value
+                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
+            basic_string&
+        >::type
+    _LIBCPP_INLINE_VISIBILITY
+    append(_InputIterator __first, _InputIterator __last) {
+      const basic_string __temp (__first, __last, __alloc());
+      append(__temp.data(), __temp.size());
+      return *this;
+    }
+    template<class _ForwardIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __is_forward_iterator<_ForwardIterator>::value
+                && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
+            basic_string&
+        >::type
+    _LIBCPP_INLINE_VISIBILITY
+    append(_ForwardIterator __first, _ForwardIterator __last) {
+      return __append_forward_unsafe(__first, __last);
+    }
+
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& append(initializer_list<value_type> __il) {return append(__il.begin(), __il.size());}
+#endif  // _LIBCPP_CXX03_LANG
+
+    void push_back(value_type __c);
+    _LIBCPP_INLINE_VISIBILITY
+    void pop_back();
+    _LIBCPP_INLINE_VISIBILITY reference       front();
+    _LIBCPP_INLINE_VISIBILITY const_reference front() const;
+    _LIBCPP_INLINE_VISIBILITY reference       back();
+    _LIBCPP_INLINE_VISIBILITY const_reference back() const;
+
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& assign(__self_view __sv) { return assign(__sv.data(), __sv.size()); }
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& assign(const basic_string& __str) { return *this = __str; }
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& assign(basic_string&& __str)
+        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
+        {*this = _VSTD::move(__str); return *this;}
+#endif
+    basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
+    template <class _Tp>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+            basic_string&
+        >::type
+                  assign(const _Tp & __t, size_type __pos, size_type __n=npos);
+    basic_string& assign(const value_type* __s, size_type __n);
+    basic_string& assign(const value_type* __s);
+    basic_string& assign(size_type __n, value_type __c);
+    template<class _InputIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+           __is_exactly_input_iterator<_InputIterator>::value
+                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
+            basic_string&
+        >::type
+        assign(_InputIterator __first, _InputIterator __last);
+    template<class _ForwardIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __is_forward_iterator<_ForwardIterator>::value
+                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
+            basic_string&
+        >::type
+        assign(_ForwardIterator __first, _ForwardIterator __last);
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& assign(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
+#endif  // _LIBCPP_CXX03_LANG
+
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& insert(size_type __pos1, const basic_string& __str);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& insert(size_type __pos1, __self_view __sv) { return insert(__pos1, __sv.data(), __sv.size()); }
+    template <class _Tp>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+            basic_string&
+        >::type
+                  insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n=npos);
+    basic_string& insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n=npos);
+    basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
+    basic_string& insert(size_type __pos, const value_type* __s);
+    basic_string& insert(size_type __pos, size_type __n, value_type __c);
+    iterator      insert(const_iterator __pos, value_type __c);
+    _LIBCPP_INLINE_VISIBILITY
+    iterator      insert(const_iterator __pos, size_type __n, value_type __c);
+    template<class _InputIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+           __is_exactly_input_iterator<_InputIterator>::value
+                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
+            iterator
+        >::type
+        insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
+    template<class _ForwardIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __is_forward_iterator<_ForwardIterator>::value
+                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
+            iterator
+        >::type
+        insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    iterator insert(const_iterator __pos, initializer_list<value_type> __il)
+                    {return insert(__pos, __il.begin(), __il.end());}
+#endif  // _LIBCPP_CXX03_LANG
+
+    basic_string& erase(size_type __pos = 0, size_type __n = npos);
+    _LIBCPP_INLINE_VISIBILITY
+    iterator      erase(const_iterator __pos);
+    _LIBCPP_INLINE_VISIBILITY
+    iterator      erase(const_iterator __first, const_iterator __last);
+
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& replace(size_type __pos1, size_type __n1, __self_view __sv) { return replace(__pos1, __n1, __sv.data(), __sv.size()); }
+    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos);
+    template <class _Tp>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+            basic_string&
+        >::type
+                  replace(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos);
+    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
+    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
+    basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& replace(const_iterator __i1, const_iterator __i2, const basic_string& __str);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& replace(const_iterator __i1, const_iterator __i2, __self_view __sv) { return replace(__i1 - begin(), __i2 - __i1, __sv); }
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s);
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string& replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c);
+    template<class _InputIterator>
+    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
+    typename enable_if
+        <
+            __is_input_iterator<_InputIterator>::value,
+            basic_string&
+        >::type
+        replace(const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2);
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    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
+
+    size_type copy(value_type* __s, size_type __n, size_type __pos = 0) const;
+    _LIBCPP_INLINE_VISIBILITY
+    basic_string substr(size_type __pos = 0, size_type __n = npos) const;
+
+    _LIBCPP_INLINE_VISIBILITY
+    void swap(basic_string& __str)
+#if _LIBCPP_STD_VER >= 14
+        _NOEXCEPT_DEBUG;
+#else
+        _NOEXCEPT_DEBUG_(!__alloc_traits::propagate_on_container_swap::value ||
+                    __is_nothrow_swappable<allocator_type>::value);
+#endif
+
+    _LIBCPP_INLINE_VISIBILITY
+    const value_type* c_str() const _NOEXCEPT {return data();}
+    _LIBCPP_INLINE_VISIBILITY
+    const value_type* data() const _NOEXCEPT  {return _VSTD::__to_raw_pointer(__get_pointer());}
+#if _LIBCPP_STD_VER > 14 || defined(_LIBCPP_BUILDING_LIBRARY)
+    _LIBCPP_INLINE_VISIBILITY
+    value_type* data()             _NOEXCEPT  {return _VSTD::__to_raw_pointer(__get_pointer());}
+#endif
+
+    _LIBCPP_INLINE_VISIBILITY
+    allocator_type get_allocator() const _NOEXCEPT {return __alloc();}
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find(__self_view __sv, size_type __pos = 0) const _NOEXCEPT;
+    size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
+    size_type find(value_type __c, size_type __pos = 0) const _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type rfind(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type rfind(__self_view __sv, size_type __pos = npos) const _NOEXCEPT;
+    size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type rfind(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
+    size_type rfind(value_type __c, size_type __pos = npos) const _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_of(__self_view __sv, size_type __pos = 0) const _NOEXCEPT;
+    size_type find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_of(__self_view __sv, size_type __pos = npos) const _NOEXCEPT;
+    size_type find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_not_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_not_of(__self_view __sv, size_type __pos = 0) const _NOEXCEPT;
+    size_type find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_not_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_first_not_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_not_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_not_of(__self_view __sv, size_type __pos = npos) const _NOEXCEPT;
+    size_type find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_not_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    size_type find_last_not_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
+
+    _LIBCPP_INLINE_VISIBILITY
+    int compare(const basic_string& __str) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    int compare(__self_view __sv) const _NOEXCEPT;
+    _LIBCPP_INLINE_VISIBILITY
+    int compare(size_type __pos1, size_type __n1, __self_view __sv) const;
+    _LIBCPP_INLINE_VISIBILITY
+    int compare(size_type __pos1, size_type __n1, const basic_string& __str) const;
+    int compare(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos) const;
+    template <class _Tp>
+    inline _LIBCPP_INLINE_VISIBILITY
+        typename enable_if
+        <
+            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+            int
+        >::type
+        compare(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos) const;
+    int compare(const value_type* __s) const _NOEXCEPT;
+    int compare(size_type __pos1, size_type __n1, const value_type* __s) const;
+    int compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;
+
+#if _LIBCPP_STD_VER > 17
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool starts_with(__self_view __sv) const _NOEXCEPT
+    { return __self_view(data(), size()).starts_with(__sv); }
+
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool starts_with(value_type __c) const _NOEXCEPT
+    { return !empty() && _Traits::eq(front(), __c); }
+
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool starts_with(const value_type* __s) const _NOEXCEPT
+    { return starts_with(__self_view(__s)); }
+
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool ends_with(__self_view __sv) const _NOEXCEPT
+    { return __self_view(data(), size()).ends_with( __sv); }
+
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool ends_with(value_type __c) const _NOEXCEPT
+    { return !empty() && _Traits::eq(back(), __c); }
+
+    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+    bool ends_with(const value_type* __s) const _NOEXCEPT
+    { return ends_with(__self_view(__s)); }
+#endif
+
+    _LIBCPP_INLINE_VISIBILITY bool __invariants() const;
+
+    _LIBCPP_INLINE_VISIBILITY
+    bool __is_long() const _NOEXCEPT
+        {return bool(__r_.first().__s.__size_ & __short_mask);}
+
+#if _LIBCPP_DEBUG_LEVEL >= 2
+
+    bool __dereferenceable(const const_iterator* __i) const;
+    bool __decrementable(const const_iterator* __i) const;
+    bool __addable(const const_iterator* __i, ptrdiff_t __n) const;
+    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const;
+
+#endif  // _LIBCPP_DEBUG_LEVEL >= 2
+
+private:
+    _LIBCPP_INLINE_VISIBILITY
+    allocator_type& __alloc() _NOEXCEPT
+        {return __r_.second();}
+    _LIBCPP_INLINE_VISIBILITY
+    const allocator_type& __alloc() const _NOEXCEPT
+        {return __r_.second();}
+
+#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __set_short_size(size_type __s) _NOEXCEPT
+#   ifdef _LIBCPP_BIG_ENDIAN
+        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
+#   else
+        {__r_.first().__s.__size_ = (unsigned char)(__s);}
+#   endif
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type __get_short_size() const _NOEXCEPT
+#   ifdef _LIBCPP_BIG_ENDIAN
+        {return __r_.first().__s.__size_ >> 1;}
+#   else
+        {return __r_.first().__s.__size_;}
+#   endif
+
+#else  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __set_short_size(size_type __s) _NOEXCEPT
+#   ifdef _LIBCPP_BIG_ENDIAN
+        {__r_.first().__s.__size_ = (unsigned char)(__s);}
+#   else
+        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
+#   endif
+
+    _LIBCPP_INLINE_VISIBILITY
+    size_type __get_short_size() const _NOEXCEPT
+#   ifdef _LIBCPP_BIG_ENDIAN
+        {return __r_.first().__s.__size_;}
+#   else
+        {return __r_.first().__s.__size_ >> 1;}
+#   endif
+
+#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __set_long_size(size_type __s) _NOEXCEPT
+        {__r_.first().__l.__size_ = __s;}
+    _LIBCPP_INLINE_VISIBILITY
+    size_type __get_long_size() const _NOEXCEPT
+        {return __r_.first().__l.__size_;}
+    _LIBCPP_INLINE_VISIBILITY
+    void __set_size(size_type __s) _NOEXCEPT
+        {if (__is_long()) __set_long_size(__s); else __set_short_size(__s);}
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __set_long_cap(size_type __s) _NOEXCEPT
+        {__r_.first().__l.__cap_  = __long_mask | __s;}
+    _LIBCPP_INLINE_VISIBILITY
+    size_type __get_long_cap() const _NOEXCEPT
+        {return __r_.first().__l.__cap_ & size_type(~__long_mask);}
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __set_long_pointer(pointer __p) _NOEXCEPT
+        {__r_.first().__l.__data_ = __p;}
+    _LIBCPP_INLINE_VISIBILITY
+    pointer __get_long_pointer() _NOEXCEPT
+        {return __r_.first().__l.__data_;}
+    _LIBCPP_INLINE_VISIBILITY
+    const_pointer __get_long_pointer() const _NOEXCEPT
+        {return __r_.first().__l.__data_;}
+    _LIBCPP_INLINE_VISIBILITY
+    pointer __get_short_pointer() _NOEXCEPT
+        {return pointer_traits<pointer>::pointer_to(__r_.first().__s.__data_[0]);}
+    _LIBCPP_INLINE_VISIBILITY
+    const_pointer __get_short_pointer() const _NOEXCEPT
+        {return pointer_traits<const_pointer>::pointer_to(__r_.first().__s.__data_[0]);}
+    _LIBCPP_INLINE_VISIBILITY
+    pointer __get_pointer() _NOEXCEPT
+        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
+    _LIBCPP_INLINE_VISIBILITY
+    const_pointer __get_pointer() const _NOEXCEPT
+        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __zero() _NOEXCEPT
+        {
+            size_type (&__a)[__n_words] = __r_.first().__r.__words;
+            for (unsigned __i = 0; __i < __n_words; ++__i)
+                __a[__i] = 0;
+        }
+
+    template <size_type __a> static
+        _LIBCPP_INLINE_VISIBILITY
+        size_type __align_it(size_type __s) _NOEXCEPT
+            {return (__s + (__a-1)) & ~(__a-1);}
+    enum {__alignment = 16};
+    static _LIBCPP_INLINE_VISIBILITY
+    size_type __recommend(size_type __s) _NOEXCEPT
+        {return (__s < __min_cap ? static_cast<size_type>(__min_cap) :
+                 __align_it<sizeof(value_type) < __alignment ?
+                            __alignment/sizeof(value_type) : 1 > (__s+1)) - 1;}
+
+    inline
+    void __init(const value_type* __s, size_type __sz, size_type __reserve);
+    inline
+    void __init(const value_type* __s, size_type __sz);
+    inline
+    void __init(size_type __n, value_type __c);
+
+    template <class _InputIterator>
+    inline
+    typename enable_if
+    <
+        __is_exactly_input_iterator<_InputIterator>::value,
+        void
+    >::type
+    __init(_InputIterator __first, _InputIterator __last);
+
+    template <class _ForwardIterator>
+    inline
+    typename enable_if
+    <
+        __is_forward_iterator<_ForwardIterator>::value,
+        void
+    >::type
+    __init(_ForwardIterator __first, _ForwardIterator __last);
+
+    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);
+    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);
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __erase_to_end(size_type __pos);
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __copy_assign_alloc(const basic_string& __str)
+        {__copy_assign_alloc(__str, integral_constant<bool,
+                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __copy_assign_alloc(const basic_string& __str, true_type)
+        {
+            if (__alloc() == __str.__alloc())
+                __alloc() = __str.__alloc();
+            else
+            {
+                if (!__str.__is_long())
+                {
+                    clear();
+                    shrink_to_fit();
+                    __alloc() = __str.__alloc();
+                }
+                else
+                {
+                    allocator_type __a = __str.__alloc();
+                    pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
+                    clear();
+                    shrink_to_fit();
+                    __alloc() = _VSTD::move(__a);
+                    __set_long_pointer(__p);
+                    __set_long_cap(__str.__get_long_cap());
+                    __set_long_size(__str.size());
+                }
+            }
+        }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT
+        {}
+
+#ifndef _LIBCPP_CXX03_LANG
+    _LIBCPP_INLINE_VISIBILITY
+    void __move_assign(basic_string& __str, false_type)
+        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
+    _LIBCPP_INLINE_VISIBILITY
+    void __move_assign(basic_string& __str, true_type)
+#if _LIBCPP_STD_VER > 14
+        _NOEXCEPT;
+#else
+        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
+#endif
+#endif
+
+    _LIBCPP_INLINE_VISIBILITY
+    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_INLINE_VISIBILITY
+    void __move_assign_alloc(basic_string& __c, true_type)
+        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
+        {
+            __alloc() = _VSTD::move(__c.__alloc());
+        }
+
+    _LIBCPP_INLINE_VISIBILITY
+    void __move_assign_alloc(basic_string&, false_type)
+        _NOEXCEPT
+        {}
+
+    _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
+    _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
+
+    friend basic_string operator+<>(const basic_string&, const basic_string&);
+    friend basic_string operator+<>(const value_type*, const basic_string&);
+    friend basic_string operator+<>(value_type, const basic_string&);
+    friend basic_string operator+<>(const basic_string&, const value_type*);
+    friend basic_string operator+<>(const basic_string&, value_type);
+};
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+basic_string<_CharT, _Traits, _Allocator>::__invalidate_all_iterators()
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__invalidate_all(this);
+#endif  // _LIBCPP_DEBUG_LEVEL >= 2
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+basic_string<_CharT, _Traits, _Allocator>::__invalidate_iterators_past(size_type
+#if _LIBCPP_DEBUG_LEVEL >= 2
+                                                                        __pos
+#endif
+                                                                      )
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __c_node* __c = __get_db()->__find_c_and_lock(this);
+    if (__c)
+    {
+        const_pointer __new_last = __get_pointer() + __pos;
+        for (__i_node** __p = __c->end_; __p != __c->beg_; )
+        {
+            --__p;
+            const_iterator* __i = static_cast<const_iterator*>((*__p)->__i_);
+            if (__i->base() > __new_last)
+            {
+                (*__p)->__c_ = nullptr;
+                if (--__c->end_ != __p)
+                    memmove(__p, __p+1, (__c->end_ - __p)*sizeof(__i_node*));
+            }
+        }
+        __get_db()->unlock();
+    }
+#endif  // _LIBCPP_DEBUG_LEVEL >= 2
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string()
+    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+    __zero();
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
+#if _LIBCPP_STD_VER <= 14
+        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
+#else
+        _NOEXCEPT
+#endif
+: __r_(__second_tag(), __a)
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+    __zero();
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+void basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s,
+                                                       size_type __sz,
+                                                       size_type __reserve)
+{
+    if (__reserve > max_size())
+        this->__throw_length_error();
+    pointer __p;
+    if (__reserve < __min_cap)
+    {
+        __set_short_size(__sz);
+        __p = __get_short_pointer();
+    }
+    else
+    {
+        size_type __cap = __recommend(__reserve);
+        __p = __alloc_traits::allocate(__alloc(), __cap+1);
+        __set_long_pointer(__p);
+        __set_long_cap(__cap+1);
+        __set_long_size(__sz);
+    }
+    traits_type::copy(_VSTD::__to_raw_pointer(__p), __s, __sz);
+    traits_type::assign(__p[__sz], value_type());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+void
+basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz)
+{
+    if (__sz > max_size())
+        this->__throw_length_error();
+    pointer __p;
+    if (__sz < __min_cap)
+    {
+        __set_short_size(__sz);
+        __p = __get_short_pointer();
+    }
+    else
+    {
+        size_type __cap = __recommend(__sz);
+        __p = __alloc_traits::allocate(__alloc(), __cap+1);
+        __set_long_pointer(__p);
+        __set_long_cap(__cap+1);
+        __set_long_size(__sz);
+    }
+    traits_type::copy(_VSTD::__to_raw_pointer(__p), __s, __sz);
+    traits_type::assign(__p[__sz], value_type());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s)
+{
+    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*) detected nullptr");
+    __init(__s, traits_type::length(__s));
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, const _Allocator& __a)
+    : __r_(__second_tag(), __a)
+{
+    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
+    __init(__s, traits_type::length(__s));
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n)
+{
+    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
+    __init(__s, __n);
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
+    : __r_(__second_tag(), __a)
+{
+    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
+    __init(__s, __n);
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str)
+    : __r_(__second_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc()))
+{
+    if (!__str.__is_long())
+        __r_.first().__r = __str.__r_.first().__r;
+    else
+        __init(_VSTD::__to_raw_pointer(__str.__get_long_pointer()), __str.__get_long_size());
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>::basic_string(
+    const basic_string& __str, const allocator_type& __a)
+    : __r_(__second_tag(), __a)
+{
+    if (!__str.__is_long())
+        __r_.first().__r = __str.__r_.first().__r;
+    else
+        __init(_VSTD::__to_raw_pointer(__str.__get_long_pointer()), __str.__get_long_size());
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str)
+#if _LIBCPP_STD_VER <= 14
+        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
+#else
+        _NOEXCEPT
+#endif
+    : __r_(_VSTD::move(__str.__r_))
+{
+    __str.__zero();
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+    if (__is_long())
+        __get_db()->swap(this, &__str);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str, const allocator_type& __a)
+    : __r_(__second_tag(), __a)
+{
+    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
+        __init(_VSTD::__to_raw_pointer(__str.__get_long_pointer()), __str.__get_long_size());
+    else
+    {
+        __r_.first().__r = __str.__r_.first().__r;
+        __str.__zero();
+    }
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+    if (__is_long())
+        __get_db()->swap(this, &__str);
+#endif
+}
+
+#endif  // _LIBCPP_CXX03_LANG
+
+template <class _CharT, class _Traits, class _Allocator>
+void
+basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c)
+{
+    if (__n > max_size())
+        this->__throw_length_error();
+    pointer __p;
+    if (__n < __min_cap)
+    {
+        __set_short_size(__n);
+        __p = __get_short_pointer();
+    }
+    else
+    {
+        size_type __cap = __recommend(__n);
+        __p = __alloc_traits::allocate(__alloc(), __cap+1);
+        __set_long_pointer(__p);
+        __set_long_cap(__cap+1);
+        __set_long_size(__n);
+    }
+    traits_type::assign(_VSTD::__to_raw_pointer(__p), __n, __c);
+    traits_type::assign(__p[__n], value_type());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c)
+{
+    __init(__n, __c);
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c, const _Allocator& __a)
+    : __r_(__second_tag(), __a)
+{
+    __init(__n, __c);
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str,
+                                                        size_type __pos, size_type __n,
+                                                        const _Allocator& __a)
+    : __r_(__second_tag(), __a)
+{
+    size_type __str_sz = __str.size();
+    if (__pos > __str_sz)
+        this->__throw_out_of_range();
+    __init(__str.data() + __pos, _VSTD::min(__n, __str_sz - __pos));
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str, size_type __pos,
+                                                        const _Allocator& __a)
+    : __r_(__second_tag(), __a)
+{
+    size_type __str_sz = __str.size();
+    if (__pos > __str_sz)
+        this->__throw_out_of_range();
+    __init(__str.data() + __pos, __str_sz - __pos);
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template <class _Tp>
+basic_string<_CharT, _Traits, _Allocator>::basic_string(
+             const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a,
+             typename enable_if<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value, void>::type *)
+    : __r_(__second_tag(), __a)
+{
+    __self_view __sv = __self_view(__t).substr(__pos, __n);
+    __init(__sv.data(), __sv.size());
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(__self_view __sv)
+{
+    __init(__sv.data(), __sv.size());
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(__self_view __sv, const _Allocator& __a)
+    : __r_(__second_tag(), __a)
+{
+    __init(__sv.data(), __sv.size());
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template <class _InputIterator>
+typename enable_if
+<
+    __is_exactly_input_iterator<_InputIterator>::value,
+    void
+>::type
+basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
+{
+    __zero();
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    try
+    {
+#endif  // _LIBCPP_NO_EXCEPTIONS
+    for (; __first != __last; ++__first)
+        push_back(*__first);
+#ifndef _LIBCPP_NO_EXCEPTIONS
+    }
+    catch (...)
+    {
+        if (__is_long())
+            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
+        throw;
+    }
+#endif  // _LIBCPP_NO_EXCEPTIONS
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template <class _ForwardIterator>
+typename enable_if
+<
+    __is_forward_iterator<_ForwardIterator>::value,
+    void
+>::type
+basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last)
+{
+    size_type __sz = static_cast<size_type>(_VSTD::distance(__first, __last));
+    if (__sz > max_size())
+        this->__throw_length_error();
+    pointer __p;
+    if (__sz < __min_cap)
+    {
+        __set_short_size(__sz);
+        __p = __get_short_pointer();
+    }
+    else
+    {
+        size_type __cap = __recommend(__sz);
+        __p = __alloc_traits::allocate(__alloc(), __cap+1);
+        __set_long_pointer(__p);
+        __set_long_cap(__cap+1);
+        __set_long_size(__sz);
+    }
+    for (; __first != __last; ++__first, (void) ++__p)
+        traits_type::assign(*__p, *__first);
+    traits_type::assign(*__p, value_type());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template<class _InputIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last)
+{
+    __init(__first, __last);
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template<class _InputIterator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last,
+                                                        const allocator_type& __a)
+    : __r_(__second_tag(), __a)
+{
+    __init(__first, __last);
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>::basic_string(
+    initializer_list<_CharT> __il)
+{
+    __init(__il.begin(), __il.end());
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+
+basic_string<_CharT, _Traits, _Allocator>::basic_string(
+    initializer_list<_CharT> __il, const _Allocator& __a)
+    : __r_(__second_tag(), __a)
+{
+    __init(__il.begin(), __il.end());
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__insert_c(this);
+#endif
+}
+
+#endif  // _LIBCPP_CXX03_LANG
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>::~basic_string()
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    __get_db()->__erase_c(this);
+#endif
+    if (__is_long())
+        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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)
+        this->__throw_length_error();
+    pointer __old_p = __get_pointer();
+    size_type __cap = __old_cap < __ms / 2 - __alignment ?
+                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
+                          __ms - 1;
+    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
+    __invalidate_all_iterators();
+    if (__n_copy != 0)
+        traits_type::copy(_VSTD::__to_raw_pointer(__p),
+                          _VSTD::__to_raw_pointer(__old_p), __n_copy);
+    if (__n_add != 0)
+        traits_type::copy(_VSTD::__to_raw_pointer(__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(_VSTD::__to_raw_pointer(__p) + __n_copy + __n_add,
+                          _VSTD::__to_raw_pointer(__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(__cap+1);
+    __old_sz = __n_copy + __n_add + __sec_cp_sz;
+    __set_long_size(__old_sz);
+    traits_type::assign(__p[__old_sz], value_type());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+void
+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)
+        this->__throw_length_error();
+    pointer __old_p = __get_pointer();
+    size_type __cap = __old_cap < __ms / 2 - __alignment ?
+                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
+                          __ms - 1;
+    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
+    __invalidate_all_iterators();
+    if (__n_copy != 0)
+        traits_type::copy(_VSTD::__to_raw_pointer(__p),
+                          _VSTD::__to_raw_pointer(__old_p), __n_copy);
+    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
+    if (__sec_cp_sz != 0)
+        traits_type::copy(_VSTD::__to_raw_pointer(__p) + __n_copy + __n_add,
+                          _VSTD::__to_raw_pointer(__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(__cap+1);
+}
+
+// assign
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
+{
+    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
+    size_type __cap = capacity();
+    if (__cap >= __n)
+    {
+        value_type* __p = _VSTD::__to_raw_pointer(__get_pointer());
+        traits_type::move(__p, __s, __n);
+        traits_type::assign(__p[__n], value_type());
+        __set_size(__n);
+        __invalidate_iterators_past(__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>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
+{
+    size_type __cap = capacity();
+    if (__cap < __n)
+    {
+        size_type __sz = size();
+        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
+    }
+    else
+        __invalidate_iterators_past(__n);
+    value_type* __p = _VSTD::__to_raw_pointer(__get_pointer());
+    traits_type::assign(__p, __n, __c);
+    traits_type::assign(__p[__n], value_type());
+    __set_size(__n);
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c)
+{
+    pointer __p;
+    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());
+    __invalidate_iterators_past(1);
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
+{
+    if (this != &__str)
+    {
+        __copy_assign_alloc(__str);
+        assign(__str.data(), __str.size());
+    }
+    return *this;
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+void
+basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
+#if _LIBCPP_STD_VER > 14
+    _NOEXCEPT
+#else
+    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
+#endif
+{
+    clear();
+    shrink_to_fit();
+    __r_.first() = __str.__r_.first();
+    __move_assign_alloc(__str);
+    __str.__zero();
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::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;
+}
+
+#endif
+
+template <class _CharT, class _Traits, class _Allocator>
+template<class _InputIterator>
+typename enable_if
+<
+     __is_exactly_input_iterator <_InputIterator>::value
+          || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
+    basic_string<_CharT, _Traits, _Allocator>&
+>::type
+basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
+{
+    const basic_string __temp(__first, __last, __alloc());
+    assign(__temp.data(), __temp.size());
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template<class _ForwardIterator>
+typename enable_if
+<
+    __is_forward_iterator<_ForwardIterator>::value
+         && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
+    basic_string<_CharT, _Traits, _Allocator>&
+>::type
+basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
+{
+    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
+    size_type __cap = capacity();
+    if (__cap < __n)
+    {
+        size_type __sz = size();
+        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
+    }
+    else
+        __invalidate_iterators_past(__n);
+    pointer __p = __get_pointer();
+    for (; __first != __last; ++__first, ++__p)
+        traits_type::assign(*__p, *__first);
+    traits_type::assign(*__p, value_type());
+    __set_size(__n);
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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)
+        this->__throw_out_of_range();
+    return assign(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template <class _Tp>
+typename enable_if
+<
+    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+    basic_string<_CharT, _Traits, _Allocator>&
+>::type
+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)
+        this->__throw_out_of_range();
+    return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
+}
+
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
+{
+    _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
+    return assign(__s, traits_type::length(__s));
+}
+
+// append
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
+{
+    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
+    size_type __cap = capacity();
+    size_type __sz = size();
+    if (__cap - __sz >= __n)
+    {
+        if (__n)
+        {
+            value_type* __p = _VSTD::__to_raw_pointer(__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>
+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(__cap, __sz + __n - __cap, __sz, __sz, 0);
+        pointer __p = __get_pointer();
+        traits_type::assign(_VSTD::__to_raw_pointer(__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>
+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(__cap, 1, __sz, __sz, 0);
+        __is_short = !__is_long();
+    }
+    pointer __p;
+    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 _Tp>
+bool __ptr_in_range (const _Tp* __p, const _Tp* __first, const _Tp* __last)
+{
+    return __first <= __p && __p < __last;
+}
+
+template <class _Tp1, class _Tp2>
+bool __ptr_in_range (const _Tp1*, const _Tp2*, const _Tp2*)
+{
+    return false;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template<class _ForwardIterator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::__append_forward_unsafe(
+    _ForwardIterator __first, _ForwardIterator __last)
+{
+    static_assert(__is_forward_iterator<_ForwardIterator>::value,
+                  "function requires a ForwardIterator");
+    size_type __sz = size();
+    size_type __cap = capacity();
+    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
+    if (__n)
+    {
+        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
+        _CharRef __tmp_ref = *__first;
+        if (__ptr_in_range(_VSTD::addressof(__tmp_ref), data(), data() + size()))
+        {
+            const basic_string __temp (__first, __last, __alloc());
+            append(__temp.data(), __temp.size());
+        }
+        else 
+        {
+            if (__cap - __sz < __n)
+                __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
+            pointer __p = __get_pointer() + __sz;
+            for (; __first != __last; ++__p, ++__first)
+                traits_type::assign(*__p, *__first);
+            traits_type::assign(*__p, value_type());
+            __set_size(__sz + __n);
+        }
+    }
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str)
+{
+    return append(__str.data(), __str.size());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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)
+        this->__throw_out_of_range();
+    return append(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template <class _Tp>
+    typename enable_if
+    <
+        __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+        basic_string<_CharT, _Traits, _Allocator>&
+    >::type
+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)
+        this->__throw_out_of_range();
+    return append(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s)
+{
+    _LIBCPP_ASSERT(__s != nullptr, "string::append received nullptr");
+    return append(__s, traits_type::length(__s));
+}
+
+// insert
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n)
+{
+    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::insert received nullptr");
+    size_type __sz = size();
+    if (__pos > __sz)
+        this->__throw_out_of_range();
+    size_type __cap = capacity();
+    if (__cap - __sz >= __n)
+    {
+        if (__n)
+        {
+            value_type* __p = _VSTD::__to_raw_pointer(__get_pointer());
+            size_type __n_move = __sz - __pos;
+            if (__n_move != 0)
+            {
+                if (__p + __pos <= __s && __s < __p + __sz)
+                    __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>
+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)
+        this->__throw_out_of_range();
+    if (__n)
+    {
+        size_type __cap = capacity();
+        value_type* __p;
+        if (__cap - __sz >= __n)
+        {
+            __p = _VSTD::__to_raw_pointer(__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(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
+            __p = _VSTD::__to_raw_pointer(__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>
+typename enable_if
+<
+   __is_exactly_input_iterator<_InputIterator>::value
+        || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
+   typename basic_string<_CharT, _Traits, _Allocator>::iterator
+>::type
+basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
+        "string::insert(iterator, range) called with an iterator not"
+        " referring to this string");
+#endif
+    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>
+typename enable_if
+<
+    __is_forward_iterator<_ForwardIterator>::value
+        && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
+    typename basic_string<_CharT, _Traits, _Allocator>::iterator
+>::type
+basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
+        "string::insert(iterator, range) called with an iterator not"
+        " referring to this string");
+#endif
+    size_type __ip = static_cast<size_type>(__pos - begin());
+    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
+    if (__n)
+    {
+        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
+        _CharRef __tmp_char = *__first;
+        if (__ptr_in_range(_VSTD::addressof(__tmp_char), data(), data() + size()))
+        {
+            const basic_string __temp(__first, __last, __alloc());
+            return insert(__pos, __temp.data(), __temp.data() + __temp.size());
+        }
+
+        size_type __sz = size();
+        size_type __cap = capacity();
+        value_type* __p;
+        if (__cap - __sz >= __n)
+        {
+            __p = _VSTD::__to_raw_pointer(__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(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
+            __p = _VSTD::__to_raw_pointer(__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 _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str)
+{
+    return insert(__pos1, __str.data(), __str.size());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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)
+        this->__throw_out_of_range();
+    return insert(__pos1, __str.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template <class _Tp>
+typename enable_if
+<
+    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+    basic_string<_CharT, _Traits, _Allocator>&
+>::type
+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)
+        this->__throw_out_of_range();
+    return insert(__pos1, __sv.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s)
+{
+    _LIBCPP_ASSERT(__s != nullptr, "string::insert received nullptr");
+    return insert(__pos, __s, traits_type::length(__s));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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(__cap, 1, __sz, __ip, 0, 1);
+        __p = _VSTD::__to_raw_pointer(__get_long_pointer());
+    }
+    else
+    {
+        __p = _VSTD::__to_raw_pointer(__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);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::iterator
+basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, size_type __n, value_type __c)
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
+        "string::insert(iterator, n, value) called with an iterator not"
+        " referring to this string");
+#endif
+    difference_type __p = __pos - begin();
+    insert(static_cast<size_type>(__p), __n, __c);
+    return begin() + __p;
+}
+
+// replace
+
+template <class _CharT, class _Traits, class _Allocator>
+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(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
+    size_type __sz = size();
+    if (__pos > __sz)
+        this->__throw_out_of_range();
+    __n1 = _VSTD::min(__n1, __sz - __pos);
+    size_type __cap = capacity();
+    if (__cap - __sz + __n1 >= __n2)
+    {
+        value_type* __p = _VSTD::__to_raw_pointer(__get_pointer());
+        if (__n1 != __n2)
+        {
+            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);
+                    goto __finish;
+                }
+                if (__p + __pos < __s && __s < __p + __sz)
+                {
+                    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);
+__finish:
+// __sz += __n2 - __n1; in this and the below function below can cause unsigned integer overflow,
+// but this is a safe operation, so we disable the check.
+        __sz += __n2 - __n1;
+        __set_size(__sz);
+        __invalidate_iterators_past(__sz);
+        traits_type::assign(__p[__sz], value_type());
+    }
+    else
+        __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c)
+    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
+{
+    size_type __sz = size();
+    if (__pos > __sz)
+        this->__throw_out_of_range();
+    __n1 = _VSTD::min(__n1, __sz - __pos);
+    size_type __cap = capacity();
+    value_type* __p;
+    if (__cap - __sz + __n1 >= __n2)
+    {
+        __p = _VSTD::__to_raw_pointer(__get_pointer());
+        if (__n1 != __n2)
+        {
+            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(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
+        __p = _VSTD::__to_raw_pointer(__get_long_pointer());
+    }
+    traits_type::assign(__p + __pos, __n2, __c);
+    __sz += __n2 - __n1;
+    __set_size(__sz);
+    __invalidate_iterators_past(__sz);
+    traits_type::assign(__p[__sz], value_type());
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template<class _InputIterator>
+typename enable_if
+<
+    __is_input_iterator<_InputIterator>::value,
+    basic_string<_CharT, _Traits, _Allocator>&
+>::type
+basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
+                                                   _InputIterator __j1, _InputIterator __j2)
+{
+    const basic_string __temp(__j1, __j2, __alloc());
+    return this->replace(__i1, __i2, __temp);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str)
+{
+    return replace(__pos1, __n1, __str.data(), __str.size());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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)
+        this->__throw_out_of_range();
+    return replace(__pos1, __n1, __str.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+template <class _Tp>
+typename enable_if
+<
+    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+    basic_string<_CharT, _Traits, _Allocator>&
+>::type
+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)
+        this->__throw_out_of_range();
+    return replace(__pos1, __n1, __sv.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s)
+{
+    _LIBCPP_ASSERT(__s != nullptr, "string::replace received nullptr");
+    return replace(__pos, __n1, __s, traits_type::length(__s));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::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 _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::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);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::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);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::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);
+}
+
+// erase
+
+template <class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>&
+basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos, size_type __n)
+{
+    size_type __sz = size();
+    if (__pos > __sz)
+        this->__throw_out_of_range();
+    if (__n)
+    {
+        value_type* __p = _VSTD::__to_raw_pointer(__get_pointer());
+        __n = _VSTD::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);
+        __sz -= __n;
+        __set_size(__sz);
+        __invalidate_iterators_past(__sz);
+        traits_type::assign(__p[__sz], value_type());
+    }
+    return *this;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::iterator
+basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos)
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
+        "string::erase(iterator) called with an iterator not"
+        " referring to this string");
+#endif
+    _LIBCPP_ASSERT(__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_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::iterator
+basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last)
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__first) == this,
+        "string::erase(iterator,  iterator) called with an iterator not"
+        " referring to this string");
+#endif
+    _LIBCPP_ASSERT(__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_INLINE_VISIBILITY
+void
+basic_string<_CharT, _Traits, _Allocator>::pop_back()
+{
+    _LIBCPP_ASSERT(!empty(), "string::pop_back(): string is already empty");
+    size_type __sz;
+    if (__is_long())
+    {
+        __sz = __get_long_size() - 1;
+        __set_long_size(__sz);
+        traits_type::assign(*(__get_long_pointer() + __sz), value_type());
+    }
+    else
+    {
+        __sz = __get_short_size() - 1;
+        __set_short_size(__sz);
+        traits_type::assign(*(__get_short_pointer() + __sz), value_type());
+    }
+    __invalidate_iterators_past(__sz);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT
+{
+    __invalidate_all_iterators();
+    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);
+    }
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+basic_string<_CharT, _Traits, _Allocator>::__erase_to_end(size_type __pos)
+{
+    if (__is_long())
+    {
+        traits_type::assign(*(__get_long_pointer() + __pos), value_type());
+        __set_long_size(__pos);
+    }
+    else
+    {
+        traits_type::assign(*(__get_short_pointer() + __pos), value_type());
+        __set_short_size(__pos);
+    }
+    __invalidate_iterators_past(__pos);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::max_size() const _NOEXCEPT
+{
+    size_type __m = __alloc_traits::max_size(__alloc());
+#ifdef _LIBCPP_BIG_ENDIAN
+    return (__m <= ~__long_mask ? __m : __m/2) - __alignment;
+#else
+    return __m - __alignment;
+#endif
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+void
+basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __res_arg)
+{
+    if (__res_arg > max_size())
+        this->__throw_length_error();
+    size_type __cap = capacity();
+    size_type __sz = size();
+    __res_arg = _VSTD::max(__res_arg, __sz);
+    __res_arg = __recommend(__res_arg);
+    if (__res_arg != __cap)
+    {
+        pointer __new_data, __p;
+        bool __was_long, __now_long;
+        if (__res_arg == __min_cap - 1)
+        {
+            __was_long = true;
+            __now_long = false;
+            __new_data = __get_short_pointer();
+            __p = __get_long_pointer();
+        }
+        else
+        {
+            if (__res_arg > __cap)
+                __new_data = __alloc_traits::allocate(__alloc(), __res_arg+1);
+            else
+            {
+            #ifndef _LIBCPP_NO_EXCEPTIONS
+                try
+                {
+            #endif  // _LIBCPP_NO_EXCEPTIONS
+                    __new_data = __alloc_traits::allocate(__alloc(), __res_arg+1);
+            #ifndef _LIBCPP_NO_EXCEPTIONS
+                }
+                catch (...)
+                {
+                    return;
+                }
+            #else  // _LIBCPP_NO_EXCEPTIONS
+                if (__new_data == nullptr)
+                    return;
+            #endif  // _LIBCPP_NO_EXCEPTIONS
+            }
+            __now_long = true;
+            __was_long = __is_long();
+            __p = __get_pointer();
+        }
+        traits_type::copy(_VSTD::__to_raw_pointer(__new_data),
+                          _VSTD::__to_raw_pointer(__p), size()+1);
+        if (__was_long)
+            __alloc_traits::deallocate(__alloc(), __p, __cap+1);
+        if (__now_long)
+        {
+            __set_long_cap(__res_arg+1);
+            __set_long_size(__sz);
+            __set_long_pointer(__new_data);
+        }
+        else
+            __set_short_size(__sz);
+        __invalidate_all_iterators();
+    }
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::const_reference
+basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) const _NOEXCEPT
+{
+    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
+    return *(data() + __pos);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::reference
+basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) _NOEXCEPT
+{
+    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
+    return *(__get_pointer() + __pos);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+typename basic_string<_CharT, _Traits, _Allocator>::const_reference
+basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const
+{
+    if (__n >= size())
+        this->__throw_out_of_range();
+    return (*this)[__n];
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+typename basic_string<_CharT, _Traits, _Allocator>::reference
+basic_string<_CharT, _Traits, _Allocator>::at(size_type __n)
+{
+    if (__n >= size())
+        this->__throw_out_of_range();
+    return (*this)[__n];
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::reference
+basic_string<_CharT, _Traits, _Allocator>::front()
+{
+    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
+    return *__get_pointer();
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::const_reference
+basic_string<_CharT, _Traits, _Allocator>::front() const
+{
+    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
+    return *data();
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::reference
+basic_string<_CharT, _Traits, _Allocator>::back()
+{
+    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
+    return *(__get_pointer() + size() - 1);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::const_reference
+basic_string<_CharT, _Traits, _Allocator>::back() const
+{
+    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
+    return *(data() + size() - 1);
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+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)
+        this->__throw_out_of_range();
+    size_type __rlen = _VSTD::min(__n, __sz - __pos);
+    traits_type::copy(__s, data() + __pos, __rlen);
+    return __rlen;
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+basic_string<_CharT, _Traits, _Allocator>::substr(size_type __pos, size_type __n) const
+{
+    return basic_string(*this, __pos, __n, __alloc());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
+#if _LIBCPP_STD_VER >= 14
+        _NOEXCEPT_DEBUG
+#else
+        _NOEXCEPT_DEBUG_(!__alloc_traits::propagate_on_container_swap::value ||
+                    __is_nothrow_swappable<allocator_type>::value)
+#endif
+{
+#if _LIBCPP_DEBUG_LEVEL >= 2
+    if (!__is_long())
+        __get_db()->__invalidate_all(this);
+    if (!__str.__is_long())
+        __get_db()->__invalidate_all(&__str);
+    __get_db()->swap(this, &__str);
+#endif
+    _LIBCPP_ASSERT(
+        __alloc_traits::propagate_on_container_swap::value ||
+        __alloc_traits::is_always_equal::value ||
+        __alloc() == __str.__alloc(), "swapping non-equal allocators");
+    _VSTD::swap(__r_.first(), __str.__r_.first());
+    __swap_allocator(__alloc(), __str.__alloc());
+}
+
+// find
+
+template <class _Traits>
+struct _LIBCPP_HIDDEN __traits_eq
+{
+    typedef typename _Traits::char_type char_type;
+    _LIBCPP_INLINE_VISIBILITY
+    bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT
+        {return _Traits::eq(__x, __y);}
+};
+
+template<class _CharT, class _Traits, class _Allocator>
+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(__n == 0 || __s != nullptr, "string::find(): received nullptr");
+    return __str_find<value_type, size_type, traits_type, npos>
+        (data(), size(), __s, __pos, __n);
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __str_find<value_type, size_type, traits_type, npos>
+        (data(), size(), __str.data(), __pos, __str.size());
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::find(__self_view __sv,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __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_INLINE_VISIBILITY
+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(__s != nullptr, "string::find(): received nullptr");
+    return __str_find<value_type, size_type, traits_type, npos>
+        (data(), size(), __s, __pos, traits_type::length(__s));
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::find(value_type __c,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __str_find<value_type, size_type, traits_type, npos>
+        (data(), size(), __c, __pos);
+}
+
+// rfind
+
+template<class _CharT, class _Traits, class _Allocator>
+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(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
+    return __str_rfind<value_type, size_type, traits_type, npos>
+        (data(), size(), __s, __pos, __n);
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str,
+                                                 size_type __pos) const _NOEXCEPT
+{
+    return __str_rfind<value_type, size_type, traits_type, npos>
+        (data(), size(), __str.data(), __pos, __str.size());
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::rfind(__self_view __sv,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __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_INLINE_VISIBILITY
+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(__s != nullptr, "string::rfind(): received nullptr");
+    return __str_rfind<value_type, size_type, traits_type, npos>
+        (data(), size(), __s, __pos, traits_type::length(__s));
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c,
+                                                 size_type __pos) const _NOEXCEPT
+{
+    return __str_rfind<value_type, size_type, traits_type, npos>
+        (data(), size(), __c, __pos);
+}
+
+// find_first_of
+
+template<class _CharT, class _Traits, class _Allocator>
+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(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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 __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>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::find_first_of(__self_view __sv,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __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_INLINE_VISIBILITY
+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(__s != nullptr, "string::find_first_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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>
+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(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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 __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>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::find_last_of(__self_view __sv,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __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_INLINE_VISIBILITY
+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(__s != nullptr, "string::find_last_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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>
+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(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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 __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>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(__self_view __sv,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __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_INLINE_VISIBILITY
+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(__s != nullptr, "string::find_first_not_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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 __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>
+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(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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 __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>
+inline _LIBCPP_INLINE_VISIBILITY
+typename basic_string<_CharT, _Traits, _Allocator>::size_type
+basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(__self_view __sv,
+                                                size_type __pos) const _NOEXCEPT
+{
+    return __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_INLINE_VISIBILITY
+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(__s != nullptr, "string::find_last_not_of(): received nullptr");
+    return __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_INLINE_VISIBILITY
+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 __str_find_last_not_of<value_type, size_type, traits_type, npos>
+        (data(), size(), __c, __pos);
+}
+
+// compare
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+int
+basic_string<_CharT, _Traits, _Allocator>::compare(__self_view __sv) const _NOEXCEPT
+{
+    size_t __lhs_sz = size();
+    size_t __rhs_sz = __sv.size();
+    int __result = traits_type::compare(data(), __sv.data(),
+                                        _VSTD::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_INLINE_VISIBILITY
+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>
+int
+basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
+                                                   size_type __n1,
+                                                   const value_type* __s,
+                                                   size_type __n2) const
+{
+    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
+    size_type __sz = size();
+    if (__pos1 > __sz || __n2 == npos)
+        this->__throw_out_of_range();
+    size_type __rlen = _VSTD::min(__n1, __sz - __pos1);
+    int __r = traits_type::compare(data() + __pos1, __s, _VSTD::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>
+inline _LIBCPP_INLINE_VISIBILITY
+int
+basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
+                                                   size_type __n1,
+                                                   __self_view __sv) const
+{
+    return compare(__pos1, __n1, __sv.data(), __sv.size());
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+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>
+typename enable_if
+<
+    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
+    int
+>::type
+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>
+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>
+int
+basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT
+{
+    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
+    return compare(0, npos, __s, traits_type::length(__s));
+}
+
+template <class _CharT, class _Traits, class _Allocator>
+int
+basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
+                                                   size_type __n1,
+                                                   const value_type* __s) const
+{
+    _LIBCPP_ASSERT(__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_INLINE_VISIBILITY
+bool
+basic_string<_CharT, _Traits, _Allocator>::__invariants() const
+{
+    if (size() > capacity())
+        return false;
+    if (capacity() < __min_cap - 1)
+        return false;
+    if (data() == 0)
+        return false;
+    if (data()[size()] != value_type(0))
+        return false;
+    return true;
+}
+
+// operator==
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
+           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
+{
+    size_t __lhs_sz = __lhs.size();
+    return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
+                                                        __rhs.data(),
+                                                        __lhs_sz) == 0;
+}
+
+template<class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+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;
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const _CharT* __lhs,
+           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
+{
+    typedef basic_string<_CharT, _Traits, _Allocator> _String;
+    _LIBCPP_ASSERT(__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;
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+bool
+operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
+           const _CharT* __rhs) _NOEXCEPT
+{
+    typedef basic_string<_CharT, _Traits, _Allocator> _String;
+    _LIBCPP_ASSERT(__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;
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+bool
+operator>=(const _CharT* __lhs,
+           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
+{
+    return !(__lhs < __rhs);
+}
+
+// operator +
+
+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)
+{
+    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
+    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
+    __r.append(__rhs.data(), __rhs_sz);
+    return __r;
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const _CharT* __lhs , const basic_string<_CharT,_Traits,_Allocator>& __rhs)
+{
+    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = _Traits::length(__lhs);
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
+    __r.__init(__lhs, __lhs_sz, __lhs_sz + __rhs_sz);
+    __r.append(__rhs.data(), __rhs_sz);
+    return __r;
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Allocator>& __rhs)
+{
+    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
+    __r.__init(&__lhs, 1, 1 + __rhs_sz);
+    __r.append(__rhs.data(), __rhs_sz);
+    return __r;
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs)
+{
+    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = _Traits::length(__rhs);
+    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
+    __r.append(__rhs, __rhs_sz);
+    return __r;
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs)
+{
+    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
+    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
+    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + 1);
+    __r.push_back(__rhs);
+    return __r;
+}
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs)
+{
+    return _VSTD::move(__lhs.append(__rhs));
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
+{
+    return _VSTD::move(__rhs.insert(0, __lhs));
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
+{
+    return _VSTD::move(__lhs.append(__rhs));
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+operator+(const _CharT* __lhs , basic_string<_CharT,_Traits,_Allocator>&& __rhs)
+{
+    return _VSTD::move(__rhs.insert(0, __lhs));
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+operator+(_CharT __lhs, basic_string<_CharT,_Traits,_Allocator>&& __rhs)
+{
+    __rhs.insert(__rhs.begin(), __lhs);
+    return _VSTD::move(__rhs);
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs)
+{
+    return _VSTD::move(__lhs.append(__rhs));
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_string<_CharT, _Traits, _Allocator>
+operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs)
+{
+    __lhs.push_back(__rhs);
+    return _VSTD::move(__lhs);
+}
+
+#endif  // _LIBCPP_CXX03_LANG
+
+// swap
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+void
+swap(basic_string<_CharT, _Traits, _Allocator>& __lhs,
+     basic_string<_CharT, _Traits, _Allocator>& __rhs)
+     _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs)))
+{
+    __lhs.swap(__rhs);
+}
+
+#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
+
+typedef basic_string<char16_t> u16string;
+typedef basic_string<char32_t> u32string;
+
+#endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = 0, int __base = 10);
+
+_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = 0);
+
+_LIBCPP_FUNC_VIS string to_string(int __val);
+_LIBCPP_FUNC_VIS string to_string(unsigned __val);
+_LIBCPP_FUNC_VIS string to_string(long __val);
+_LIBCPP_FUNC_VIS string to_string(unsigned long __val);
+_LIBCPP_FUNC_VIS string to_string(long long __val);
+_LIBCPP_FUNC_VIS string to_string(unsigned long long __val);
+_LIBCPP_FUNC_VIS string to_string(float __val);
+_LIBCPP_FUNC_VIS string to_string(double __val);
+_LIBCPP_FUNC_VIS string to_string(long double __val);
+
+_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = 0, int __base = 10);
+_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = 0, int __base = 10);
+
+_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = 0);
+_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = 0);
+
+_LIBCPP_FUNC_VIS wstring to_wstring(int __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(long __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(long long __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long long __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(float __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(double __val);
+_LIBCPP_FUNC_VIS wstring to_wstring(long double __val);
+
+template<class _CharT, class _Traits, class _Allocator>
+    const typename basic_string<_CharT, _Traits, _Allocator>::size_type
+                   basic_string<_CharT, _Traits, _Allocator>::npos;
+
+template<class _CharT, class _Traits, class _Allocator>
+struct _LIBCPP_TEMPLATE_VIS hash<basic_string<_CharT, _Traits, _Allocator> >
+    : public unary_function<basic_string<_CharT, _Traits, _Allocator>, size_t>
+{
+    size_t
+        operator()(const basic_string<_CharT, _Traits, _Allocator>& __val) const _NOEXCEPT;
+};
+
+template<class _CharT, class _Traits, class _Allocator>
+size_t
+hash<basic_string<_CharT, _Traits, _Allocator> >::operator()(
+        const basic_string<_CharT, _Traits, _Allocator>& __val) const _NOEXCEPT
+{
+    return __do_string_hash(__val.data(), __val.data() + __val.size());
+}
+
+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>&
+operator>>(basic_istream<_CharT, _Traits>& __is,
+           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 __dlm);
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+basic_istream<_CharT, _Traits>&
+getline(basic_istream<_CharT, _Traits>& __is,
+        basic_string<_CharT, _Traits, _Allocator>& __str);
+
+#ifndef _LIBCPP_CXX03_LANG
+
+template<class _CharT, class _Traits, class _Allocator>
+inline _LIBCPP_INLINE_VISIBILITY
+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_INLINE_VISIBILITY
+basic_istream<_CharT, _Traits>&
+getline(basic_istream<_CharT, _Traits>&& __is,
+        basic_string<_CharT, _Traits, _Allocator>& __str);
+
+#endif  // _LIBCPP_CXX03_LANG
+
+#if _LIBCPP_DEBUG_LEVEL >= 2
+
+template<class _CharT, class _Traits, class _Allocator>
+bool
+basic_string<_CharT, _Traits, _Allocator>::__dereferenceable(const const_iterator* __i) const
+{
+    return this->data() <= _VSTD::__to_raw_pointer(__i->base()) &&
+           _VSTD::__to_raw_pointer(__i->base()) < this->data() + this->size();
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+bool
+basic_string<_CharT, _Traits, _Allocator>::__decrementable(const const_iterator* __i) const
+{
+    return this->data() < _VSTD::__to_raw_pointer(__i->base()) &&
+           _VSTD::__to_raw_pointer(__i->base()) <= this->data() + this->size();
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+bool
+basic_string<_CharT, _Traits, _Allocator>::__addable(const const_iterator* __i, ptrdiff_t __n) const
+{
+    const value_type* __p = _VSTD::__to_raw_pointer(__i->base()) + __n;
+    return this->data() <= __p && __p <= this->data() + this->size();
+}
+
+template<class _CharT, class _Traits, class _Allocator>
+bool
+basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator* __i, ptrdiff_t __n) const
+{
+    const value_type* __p = _VSTD::__to_raw_pointer(__i->base()) + __n;
+    return this->data() <= __p && __p < this->data() + this->size();
+}
+
+#endif  // _LIBCPP_DEBUG_LEVEL >= 2
+
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_string<char>)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_string<wchar_t>)
+
+#if _LIBCPP_STD_VER > 11 
+// Literal suffixes for basic_string [basic.string.literals]
+inline namespace literals
+{
+  inline namespace string_literals
+  {
+    inline _LIBCPP_INLINE_VISIBILITY
+    basic_string<char> operator "" s( const char *__str, size_t __len )
+    {
+        return basic_string<char> (__str, __len);
+    }
+
+    inline _LIBCPP_INLINE_VISIBILITY
+    basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
+    {
+        return basic_string<wchar_t> (__str, __len);
+    }
+
+    inline _LIBCPP_INLINE_VISIBILITY
+    basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
+    {
+        return basic_string<char16_t> (__str, __len);
+    }
+
+    inline _LIBCPP_INLINE_VISIBILITY
+    basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
+    {
+        return basic_string<char32_t> (__str, __len);
+    }
+  }
+}
+#endif
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif  // _LIBCPP_STRING