// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_STRING_VIEW
#define _LIBCPP_STRING_VIEW

// clang-format off

/*

    string_view synopsis

#include <compare>

namespace std {

    // 7.2, Class template basic_string_view
    template<class charT, class traits = char_traits<charT>>
        class basic_string_view;

    template<class charT, class traits>
    inline constexpr bool ranges::enable_view<basic_string_view<charT, traits>> = true;

    template<class charT, class traits>
    inline constexpr bool ranges::enable_borrowed_range<basic_string_view<charT, traits>> = true;  // C++20

    // 7.9, basic_string_view non-member comparison functions
    template<class charT, class traits>
    constexpr bool operator==(basic_string_view<charT, traits> x,
                              basic_string_view<charT, traits> y) noexcept;
    template<class charT, class traits>                                                            // Removed in C++20
    constexpr bool operator!=(basic_string_view<charT, traits> x,
                              basic_string_view<charT, traits> y) noexcept;
    template<class charT, class traits>                                                            // Removed in C++20
    constexpr bool operator< (basic_string_view<charT, traits> x,
                                 basic_string_view<charT, traits> y) noexcept;
    template<class charT, class traits>                                                            // Removed in C++20
    constexpr bool operator> (basic_string_view<charT, traits> x,
                              basic_string_view<charT, traits> y) noexcept;
    template<class charT, class traits>                                                            // Removed in C++20
    constexpr bool operator<=(basic_string_view<charT, traits> x,
                                 basic_string_view<charT, traits> y) noexcept;
    template<class charT, class traits>                                                            // Removed in C++20
    constexpr bool operator>=(basic_string_view<charT, traits> x,
                              basic_string_view<charT, traits> y) noexcept;
    template<class charT, class traits>                                                            // Since C++20
    constexpr see below operator<=>(basic_string_view<charT, traits> x,
                                    basic_string_view<charT, traits> y) noexcept;

    // see below, sufficient additional overloads of comparison functions

    // 7.10, Inserters and extractors
    template<class charT, class traits>
      basic_ostream<charT, traits>&
        operator<<(basic_ostream<charT, traits>& os,
                   basic_string_view<charT, traits> str);

    // basic_string_view typedef names
    typedef basic_string_view<char> string_view;
    typedef basic_string_view<char8_t> u8string_view; // C++20
    typedef basic_string_view<char16_t> u16string_view;
    typedef basic_string_view<char32_t> u32string_view;
    typedef basic_string_view<wchar_t> wstring_view;

    template<class charT, class traits = char_traits<charT>>
    class basic_string_view {
      public:
      // types
      typedef traits traits_type;
      typedef charT value_type;
      typedef charT* pointer;
      typedef const charT* const_pointer;
      typedef charT& reference;
      typedef const charT& const_reference;
      typedef implementation-defined const_iterator;
      typedef const_iterator iterator;
      typedef reverse_iterator<const_iterator> const_reverse_iterator;
      typedef const_reverse_iterator reverse_iterator;
      typedef size_t size_type;
      typedef ptrdiff_t difference_type;
      static constexpr size_type npos = size_type(-1);

      // 7.3, basic_string_view constructors and assignment operators
      constexpr basic_string_view() noexcept;
      constexpr basic_string_view(const basic_string_view&) noexcept = default;
      basic_string_view& operator=(const basic_string_view&) noexcept = default;
      template<class Allocator>
      constexpr basic_string_view(const charT* str);
      basic_string_view(nullptr_t) = delete; // C++23
      constexpr basic_string_view(const charT* str, size_type len);
      template <class It, class End>
      constexpr basic_string_view(It begin, End end); // C++20
      template <class Range>
      constexpr basic_string_view(Range&& r); // C++23

      // 7.4, basic_string_view iterator support
      constexpr const_iterator begin() const noexcept;
      constexpr const_iterator end() const noexcept;
      constexpr const_iterator cbegin() const noexcept;
      constexpr const_iterator cend() const noexcept;
      const_reverse_iterator rbegin() const noexcept;
      const_reverse_iterator rend() const noexcept;
      const_reverse_iterator crbegin() const noexcept;
      const_reverse_iterator crend() const noexcept;

      // 7.5, basic_string_view capacity
      constexpr size_type size() const noexcept;
      constexpr size_type length() const noexcept;
      constexpr size_type max_size() const noexcept;
      constexpr bool empty() const noexcept;

      // 7.6, basic_string_view element access
      constexpr const_reference operator[](size_type pos) const;
      constexpr const_reference at(size_type pos) const;
      constexpr const_reference front() const;
      constexpr const_reference back() const;
      constexpr const_pointer data() const noexcept;

      // 7.7, basic_string_view modifiers
      constexpr void remove_prefix(size_type n);
      constexpr void remove_suffix(size_type n);
      constexpr void swap(basic_string_view& s) noexcept;

      size_type copy(charT* s, size_type n, size_type pos = 0) const;  // constexpr in C++20

      constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
      constexpr int compare(basic_string_view s) const noexcept;
      constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const;
      constexpr int compare(size_type pos1, size_type n1,
                            basic_string_view s, size_type pos2, size_type n2) const;
      constexpr int compare(const charT* s) const;
      constexpr int compare(size_type pos1, size_type n1, const charT* s) const;
      constexpr int compare(size_type pos1, size_type n1,
                            const charT* s, size_type n2) const;
      constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept;
      constexpr size_type find(charT c, size_type pos = 0) const noexcept;
      constexpr size_type find(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
      constexpr size_type find(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
      constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept;
      constexpr size_type rfind(charT c, size_type pos = npos) const noexcept;
      constexpr size_type rfind(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
      constexpr size_type rfind(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
      constexpr size_type find_first_of(basic_string_view s, size_type pos = 0) const noexcept;
      constexpr size_type find_first_of(charT c, size_type pos = 0) const noexcept;
      constexpr size_type find_first_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
      constexpr size_type find_first_of(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
      constexpr size_type find_last_of(basic_string_view s, size_type pos = npos) const noexcept;
      constexpr size_type find_last_of(charT c, size_type pos = npos) const noexcept;
      constexpr size_type find_last_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
      constexpr size_type find_last_of(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
      constexpr size_type find_first_not_of(basic_string_view s, size_type pos = 0) const noexcept;
      constexpr size_type find_first_not_of(charT c, size_type pos = 0) const noexcept;
      constexpr size_type find_first_not_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
      constexpr size_type find_first_not_of(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
      constexpr size_type find_last_not_of(basic_string_view s, size_type pos = npos) const noexcept;
      constexpr size_type find_last_not_of(charT c, size_type pos = npos) const noexcept;
      constexpr size_type find_last_not_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
      constexpr size_type find_last_not_of(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension

      constexpr bool starts_with(basic_string_view s) const noexcept; // C++20
      constexpr bool starts_with(charT c) const noexcept;             // C++20
      constexpr bool starts_with(const charT* s) const;               // C++20
      constexpr bool ends_with(basic_string_view s) const noexcept;   // C++20
      constexpr bool ends_with(charT c) const noexcept;               // C++20
      constexpr bool ends_with(const charT* s) const;                 // C++20

      constexpr bool contains(basic_string_view s) const noexcept; // C++23
      constexpr bool contains(charT c) const noexcept;             // C++23
      constexpr bool contains(const charT* s) const;               // C++23

     private:
      const_pointer data_;  // exposition only
      size_type     size_;  // exposition only
    };

  // basic_string_view deduction guides
  template<class It, class End>
    basic_string_view(It, End) -> basic_string_view<iter_value_t<It>>; // C++20
  template<class Range>
    basic_string_view(Range&&) -> basic_string_view<ranges::range_value_t<Range>>; // C++23

  // 7.11, Hash support
  template <class T> struct hash;
  template <> struct hash<string_view>;
  template <> struct hash<u8string_view>; // C++20
  template <> struct hash<u16string_view>;
  template <> struct hash<u32string_view>;
  template <> struct hash<wstring_view>;

  constexpr basic_string_view<char>     operator""sv(const char *str,     size_t len) noexcept;
  constexpr basic_string_view<wchar_t>  operator""sv(const wchar_t *str,  size_t len) noexcept;
  constexpr basic_string_view<char8_t>  operator""sv(const char8_t *str,  size_t len) noexcept; // C++20
  constexpr basic_string_view<char16_t> operator""sv(const char16_t *str, size_t len) noexcept;
  constexpr basic_string_view<char32_t> operator""sv(const char32_t *str, size_t len) noexcept;

}  // namespace std

*/

// clang-format on

#include <__algorithm/min.h>
#include <__assert>
#include <__config>
#include <__functional/hash.h>
#include <__functional/unary_function.h>
#include <__fwd/string_view.h>
#include <__iterator/bounded_iter.h>
#include <__iterator/concepts.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/reverse_iterator.h>
#include <__iterator/wrap_iter.h>
#include <__memory/pointer_traits.h>
#include <__ranges/concepts.h>
#include <__ranges/data.h>
#include <__ranges/enable_borrowed_range.h>
#include <__ranges/enable_view.h>
#include <__ranges/size.h>
#include <__string/char_traits.h>
#include <__type_traits/is_array.h>
#include <__type_traits/is_convertible.h>
#include <__type_traits/is_same.h>
#include <__type_traits/is_standard_layout.h>
#include <__type_traits/is_trivial.h>
#include <__type_traits/remove_cvref.h>
#include <__type_traits/remove_reference.h>
#include <__type_traits/type_identity.h>
#include <cstddef>
#include <iosfwd>
#include <limits>
#include <stdexcept>
#include <version>

// standard-mandated includes

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

// [string.view.synop]
#include <compare>

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

_LIBCPP_PUSH_MACROS
#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

// TODO: This is a workaround for some vendors to carry a downstream diff to accept `nullptr` in
//       string_view constructors. This can be refactored when this exact form isn't needed anymore.
template <class _Traits>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR inline size_t
__char_traits_length_checked(const typename _Traits::char_type* __s) _NOEXCEPT {
  // This needs to be a single statement for C++11 constexpr
  return _LIBCPP_ASSERT_NON_NULL(
             __s != nullptr, "null pointer passed to non-null argument of char_traits<...>::length"),
         _Traits::length(__s);
}

template <class _CharT, class _Traits>
class basic_string_view {
public:
  // types
  using traits_type     = _Traits;
  using value_type      = _CharT;
  using pointer         = _CharT*;
  using const_pointer   = const _CharT*;
  using reference       = _CharT&;
  using const_reference = const _CharT&;
#if defined(_LIBCPP_ABI_BOUNDED_ITERATORS)
  using const_iterator = __bounded_iter<const_pointer>;
#elif defined(_LIBCPP_ABI_USE_WRAP_ITER_IN_STD_STRING_VIEW)
  using const_iterator = __wrap_iter<const_pointer>;
#else
  using const_iterator = const_pointer;
#endif
  using iterator                                = const_iterator;
  using const_reverse_iterator                  = std::reverse_iterator<const_iterator>;
  using reverse_iterator                        = const_reverse_iterator;
  using size_type                               = size_t;
  using difference_type                         = ptrdiff_t;
  static _LIBCPP_CONSTEXPR const size_type npos = -1; // size_type(-1);

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

  // [string.view.cons], construct/copy
  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view() _NOEXCEPT : __data_(nullptr), __size_(0) {}

  _LIBCPP_HIDE_FROM_ABI basic_string_view(const basic_string_view&) _NOEXCEPT = default;

  _LIBCPP_HIDE_FROM_ABI basic_string_view& operator=(const basic_string_view&) _NOEXCEPT = default;

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view(const _CharT* __s, size_type __len) _NOEXCEPT
      : __data_(__s),
        __size_(__len) {
#if _LIBCPP_STD_VER >= 14
    // Allocations must fit in `ptrdiff_t` for pointer arithmetic to work. If `__len` exceeds it, the input
    // range could not have been valid. Most likely the caller underflowed some arithmetic and inadvertently
    // passed in a negative length.
    _LIBCPP_ASSERT_VALID_INPUT_RANGE(
        __len <= static_cast<size_type>(numeric_limits<difference_type>::max()),
        "string_view::string_view(_CharT *, size_t): length does not fit in difference_type");
    _LIBCPP_ASSERT_NON_NULL(
        __len == 0 || __s != nullptr, "string_view::string_view(_CharT *, size_t): received nullptr");
#endif
  }

#if _LIBCPP_STD_VER >= 20
  template <contiguous_iterator _It, sized_sentinel_for<_It> _End>
    requires(is_same_v<iter_value_t<_It>, _CharT> && !is_convertible_v<_End, size_type>)
  constexpr _LIBCPP_HIDE_FROM_ABI basic_string_view(_It __begin, _End __end)
      : __data_(std::to_address(__begin)), __size_(__end - __begin) {
    _LIBCPP_ASSERT_VALID_INPUT_RANGE(
        (__end - __begin) >= 0, "std::string_view::string_view(iterator, sentinel) received invalid range");
  }
#endif // _LIBCPP_STD_VER >= 20

#if _LIBCPP_STD_VER >= 23
  template <class _Range>
    requires(!is_same_v<remove_cvref_t<_Range>, basic_string_view> && ranges::contiguous_range<_Range> &&
             ranges::sized_range<_Range> && is_same_v<ranges::range_value_t<_Range>, _CharT> &&
             !is_convertible_v<_Range, const _CharT*> &&
             (!requires(remove_cvref_t<_Range>& __d) { __d.operator std::basic_string_view<_CharT, _Traits>(); }))
  constexpr explicit _LIBCPP_HIDE_FROM_ABI basic_string_view(_Range&& __r)
      : __data_(ranges::data(__r)), __size_(ranges::size(__r)) {}
#endif // _LIBCPP_STD_VER >= 23

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view(const _CharT* __s)
      : __data_(__s), __size_(std::__char_traits_length_checked<_Traits>(__s)) {}

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

  // [string.view.iterators], iterators
  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return cbegin(); }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return cend(); }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT {
#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS
    return std::__make_bounded_iter(data(), data(), data() + size());
#else
    return const_iterator(__data_);
#endif
  }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT {
#ifdef _LIBCPP_ABI_BOUNDED_ITERATORS
    return std::__make_bounded_iter(data() + size(), data(), data() + size());
#else
    return const_iterator(__data_ + __size_);
#endif
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT {
    return const_reverse_iterator(cend());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT {
    return const_reverse_iterator(cbegin());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT {
    return const_reverse_iterator(cend());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT {
    return const_reverse_iterator(cbegin());
  }

  // [string.view.capacity], capacity
  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __size_; }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type length() const _NOEXCEPT { return __size_; }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
    return numeric_limits<size_type>::max() / sizeof(value_type);
  }

  _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT { return __size_ == 0; }

  // [string.view.access], element access
  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference operator[](size_type __pos) const _NOEXCEPT {
    return _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__pos < size(), "string_view[] index out of bounds"), __data_[__pos];
  }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference at(size_type __pos) const {
    return __pos >= size() ? (__throw_out_of_range("string_view::at"), __data_[0]) : __data_[__pos];
  }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference front() const _NOEXCEPT {
    return _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string_view::front(): string is empty"), __data_[0];
  }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference back() const _NOEXCEPT {
    return _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string_view::back(): string is empty"), __data_[__size_ - 1];
  }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_pointer data() const _NOEXCEPT { return __data_; }

  // [string.view.modifiers], modifiers:
  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI void remove_prefix(size_type __n) _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__n <= size(), "remove_prefix() can't remove more than size()");
    __data_ += __n;
    __size_ -= __n;
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI void remove_suffix(size_type __n) _NOEXCEPT {
    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__n <= size(), "remove_suffix() can't remove more than size()");
    __size_ -= __n;
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI void swap(basic_string_view& __other) _NOEXCEPT {
    const value_type* __p = __data_;
    __data_               = __other.__data_;
    __other.__data_       = __p;

    size_type __sz  = __size_;
    __size_         = __other.__size_;
    __other.__size_ = __sz;
  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 size_type
  copy(_CharT* __s, size_type __n, size_type __pos = 0) const {
    if (__pos > size())
      __throw_out_of_range("string_view::copy");
    size_type __rlen = std::min(__n, size() - __pos);
    _Traits::copy(__s, data() + __pos, __rlen);
    return __rlen;
  }

  _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view substr(size_type __pos = 0, size_type __n = npos) const {
    return __pos > size() ? (__throw_out_of_range("string_view::substr"), basic_string_view())
                          : basic_string_view(data() + __pos, std::min(__n, size() - __pos));
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
    size_type __rlen = std::min(size(), __sv.size());
    int __retval     = _Traits::compare(data(), __sv.data(), __rlen);
    if (__retval == 0) // first __rlen chars matched
      __retval = size() == __sv.size() ? 0 : (size() < __sv.size() ? -1 : 1);
    return __retval;
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
  compare(size_type __pos1, size_type __n1, basic_string_view __sv) const {
    return substr(__pos1, __n1).compare(__sv);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
  compare(size_type __pos1, size_type __n1, basic_string_view __sv, size_type __pos2, size_type __n2) const {
    return substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int compare(const _CharT* __s) const _NOEXCEPT {
    return compare(basic_string_view(__s));
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
  compare(size_type __pos1, size_type __n1, const _CharT* __s) const {
    return substr(__pos1, __n1).compare(basic_string_view(__s));
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
  compare(size_type __pos1, size_type __n1, const _CharT* __s, size_type __n2) const {
    return substr(__pos1, __n1).compare(basic_string_view(__s, __n2));
  }

  // find
  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): received nullptr");
    return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s.data(), __pos, __s.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type find(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
    return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find(): received nullptr");
    return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find(const _CharT* __s, size_type __pos = 0) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find(): received nullptr");
    return std::__str_find<value_type, size_type, traits_type, npos>(
        data(), size(), __s, __pos, traits_type::length(__s));
  }

  // rfind
  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  rfind(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): received nullptr");
    return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s.data(), __pos, __s.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  rfind(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
    return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  rfind(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::rfind(): received nullptr");
    return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  rfind(const _CharT* __s, size_type __pos = npos) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::rfind(): received nullptr");
    return std::__str_rfind<value_type, size_type, traits_type, npos>(
        data(), size(), __s, __pos, traits_type::length(__s));
  }

  // find_first_of
  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s.size() == 0 || __s.data() != nullptr, "string_view::find_first_of(): received nullptr");
    return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s.data(), __pos, __s.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
    return find(__c, __pos);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_first_of(): received nullptr");
    return std::__str_find_first_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_of(const _CharT* __s, size_type __pos = 0) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_first_of(): received nullptr");
    return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s, __pos, traits_type::length(__s));
  }

  // find_last_of
  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_of(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s.size() == 0 || __s.data() != nullptr, "string_view::find_last_of(): received nullptr");
    return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s.data(), __pos, __s.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
    return rfind(__c, __pos);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_last_of(): received nullptr");
    return std::__str_find_last_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_of(const _CharT* __s, size_type __pos = npos) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_last_of(): received nullptr");
    return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s, __pos, traits_type::length(__s));
  }

  // find_first_not_of
  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_not_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(
        __s.size() == 0 || __s.data() != nullptr, "string_view::find_first_not_of(): received nullptr");
    return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s.data(), __pos, __s.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_not_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
    return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_first_not_of(): received nullptr");
    return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_first_not_of(const _CharT* __s, size_type __pos = 0) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_first_not_of(): received nullptr");
    return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s, __pos, traits_type::length(__s));
  }

  // find_last_not_of
  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_not_of(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(
        __s.size() == 0 || __s.data() != nullptr, "string_view::find_last_not_of(): received nullptr");
    return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s.data(), __pos, __s.size());
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_not_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
    return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_last_not_of(): received nullptr");
    return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
  find_last_not_of(const _CharT* __s, size_type __pos = npos) const _NOEXCEPT {
    _LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_last_not_of(): received nullptr");
    return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
        data(), size(), __s, __pos, traits_type::length(__s));
  }

#if _LIBCPP_STD_VER >= 20
  constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(basic_string_view __s) const noexcept {
    return size() >= __s.size() && compare(0, __s.size(), __s) == 0;
  }

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

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

  constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(basic_string_view __s) const noexcept {
    return size() >= __s.size() && compare(size() - __s.size(), npos, __s) == 0;
  }

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

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

#if _LIBCPP_STD_VER >= 23
  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(basic_string_view __sv) const noexcept { return find(__sv) != npos; }

  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(value_type __c) const noexcept { return find(__c) != npos; }

  constexpr _LIBCPP_HIDE_FROM_ABI bool contains(const value_type* __s) const { return find(__s) != npos; }
#endif

private:
  const value_type* __data_;
  size_type __size_;
};
_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_string_view);

#if _LIBCPP_STD_VER >= 20
template <class _CharT, class _Traits>
inline constexpr bool ranges::enable_view<basic_string_view<_CharT, _Traits>> = true;

template <class _CharT, class _Traits>
inline constexpr bool ranges::enable_borrowed_range<basic_string_view<_CharT, _Traits> > = true;
#endif // _LIBCPP_STD_VER >= 20

// [string.view.deduct]

#if _LIBCPP_STD_VER >= 20
template <contiguous_iterator _It, sized_sentinel_for<_It> _End>
basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
#endif // _LIBCPP_STD_VER >= 20

#if _LIBCPP_STD_VER >= 23
template <ranges::contiguous_range _Range>
basic_string_view(_Range) -> basic_string_view<ranges::range_value_t<_Range>>;
#endif

// [string.view.comparison]

#if _LIBCPP_STD_VER >= 20

template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator==(basic_string_view<_CharT, _Traits> __lhs,
                                                type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) noexcept {
  if (__lhs.size() != __rhs.size())
    return false;
  return __lhs.compare(__rhs) == 0;
}

template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI constexpr auto operator<=>(basic_string_view<_CharT, _Traits> __lhs,
                                                 type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) noexcept {
  if constexpr (requires { typename _Traits::comparison_category; }) {
    // [string.view]/4
    static_assert(
        __comparison_category<typename _Traits::comparison_category>, "return type is not a comparison category type");
    return static_cast<typename _Traits::comparison_category>(__lhs.compare(__rhs) <=> 0);
  } else {
    return static_cast<weak_ordering>(__lhs.compare(__rhs) <=> 0);
  }
}

#else

// operator ==

template <class _CharT, class _Traits>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator==(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  if (__lhs.size() != __rhs.size())
    return false;
  return __lhs.compare(__rhs) == 0;
}

// The dummy default template parameters are used to work around a MSVC issue with mangling, see VSO-409326 for details.
// This applies to the other sufficient overloads below for the other comparison operators.
template <class _CharT, class _Traits, int = 1>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator==(basic_string_view<_CharT, _Traits> __lhs,
           __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT {
  if (__lhs.size() != __rhs.size())
    return false;
  return __lhs.compare(__rhs) == 0;
}

template <class _CharT, class _Traits, int = 2>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator==(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
           basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  if (__lhs.size() != __rhs.size())
    return false;
  return __lhs.compare(__rhs) == 0;
}

// operator !=
template <class _CharT, class _Traits>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator!=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  if (__lhs.size() != __rhs.size())
    return true;
  return __lhs.compare(__rhs) != 0;
}

template <class _CharT, class _Traits, int = 1>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator!=(basic_string_view<_CharT, _Traits> __lhs,
           __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT {
  if (__lhs.size() != __rhs.size())
    return true;
  return __lhs.compare(__rhs) != 0;
}

template <class _CharT, class _Traits, int = 2>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator!=(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
           basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  if (__lhs.size() != __rhs.size())
    return true;
  return __lhs.compare(__rhs) != 0;
}

// operator <
template <class _CharT, class _Traits>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator<(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) < 0;
}

template <class _CharT, class _Traits, int = 1>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator<(basic_string_view<_CharT, _Traits> __lhs,
          __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) < 0;
}

template <class _CharT, class _Traits, int = 2>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator<(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
          basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) < 0;
}

// operator >
template <class _CharT, class _Traits>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator>(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) > 0;
}

template <class _CharT, class _Traits, int = 1>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator>(basic_string_view<_CharT, _Traits> __lhs,
          __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) > 0;
}

template <class _CharT, class _Traits, int = 2>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator>(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
          basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) > 0;
}

// operator <=
template <class _CharT, class _Traits>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator<=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) <= 0;
}

template <class _CharT, class _Traits, int = 1>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator<=(basic_string_view<_CharT, _Traits> __lhs,
           __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) <= 0;
}

template <class _CharT, class _Traits, int = 2>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator<=(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
           basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) <= 0;
}

// operator >=
template <class _CharT, class _Traits>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator>=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) >= 0;
}

template <class _CharT, class _Traits, int = 1>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator>=(basic_string_view<_CharT, _Traits> __lhs,
           __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) >= 0;
}

template <class _CharT, class _Traits, int = 2>
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI bool
operator>=(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
           basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT {
  return __lhs.compare(__rhs) >= 0;
}

#endif //  _LIBCPP_STD_VER >= 20

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

// [string.view.hash]
template <class _CharT>
struct __string_view_hash : public __unary_function<basic_string_view<_CharT, char_traits<_CharT> >, size_t> {
  _LIBCPP_HIDE_FROM_ABI size_t operator()(const basic_string_view<_CharT, char_traits<_CharT> > __val) const _NOEXCEPT {
    return std::__do_string_hash(__val.data(), __val.data() + __val.size());
  }
};

template <>
struct hash<basic_string_view<char, char_traits<char> > > : __string_view_hash<char> {};

#ifndef _LIBCPP_HAS_NO_CHAR8_T
template <>
struct hash<basic_string_view<char8_t, char_traits<char8_t> > > : __string_view_hash<char8_t> {};
#endif

template <>
struct hash<basic_string_view<char16_t, char_traits<char16_t> > > : __string_view_hash<char16_t> {};

template <>
struct hash<basic_string_view<char32_t, char_traits<char32_t> > > : __string_view_hash<char32_t> {};

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
struct hash<basic_string_view<wchar_t, char_traits<wchar_t> > > : __string_view_hash<wchar_t> {};
#endif

#if _LIBCPP_STD_VER >= 14
inline namespace literals {
inline namespace string_view_literals {
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR basic_string_view<char>
operator""sv(const char* __str, size_t __len) _NOEXCEPT {
  return basic_string_view<char>(__str, __len);
}

#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR basic_string_view<wchar_t>
operator""sv(const wchar_t* __str, size_t __len) _NOEXCEPT {
  return basic_string_view<wchar_t>(__str, __len);
}
#  endif

#  ifndef _LIBCPP_HAS_NO_CHAR8_T
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR basic_string_view<char8_t>
operator""sv(const char8_t* __str, size_t __len) _NOEXCEPT {
  return basic_string_view<char8_t>(__str, __len);
}
#  endif

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR basic_string_view<char16_t>
operator""sv(const char16_t* __str, size_t __len) _NOEXCEPT {
  return basic_string_view<char16_t>(__str, __len);
}

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR basic_string_view<char32_t>
operator""sv(const char32_t* __str, size_t __len) _NOEXCEPT {
  return basic_string_view<char32_t>(__str, __len);
}
} // namespace string_view_literals
} // namespace literals
#endif
_LIBCPP_END_NAMESPACE_STD

_LIBCPP_POP_MACROS

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

#endif // _LIBCPP_STRING_VIEW