实验性库头文件 <experimental/ranges/iterator>

 

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标准库头文件

语言支持 <cfloat> <climits> <compare> (C++20) <contracts> (C++26) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) 概念 <concepts> (C++20) 诊断 <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) 内存管理 <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) 元编程 <type_traits> (C++11) <ratio> (C++11)

通用工具 <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) 容器 <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <hive> (C++26) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> 迭代器 <iterator> 范围 <generator> (C++23) <ranges> (C++20)

算法 <algorithm> <numeric> 字符串 <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> 文本处理 <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    数值 <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <simd> (C++26) <valarray> 时间 <chrono> (C++11) <ctime> C 兼容性 <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

输入/输出 <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) 并发支持 <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) 执行支持 <execution> (C++17)

 

实验性库头文件

执行 P2300
<experimental/execution>
文件系统 TS
<experimental/filesystem>
并行 TS (v1, v2)
experimental/algorithm experimental/execution_policy experimental/exception_list	experimental/numeric <experimental/simd> experimental/task_block
库基础 TS (v1, v2, v3)
experimental/algorithm <experimental/any> experimental/array experimental/chrono experimental/deque experimental/forward_list <experimental/functional> experimental/future experimental/iterator experimental/list experimental/map experimental/memory <experimental/memory_resource> experimental/numeric <experimental/optional> experimental/propagate_const	experimental/random experimental/ratio experimental/regex experimental/scope experimental/set experimental/source_location experimental/string <experimental/string_view> experimental/system_error experimental/tuple experimental/type_traits experimental/unordered_map experimental/unordered_set experimental/utility experimental/vector
并发 TS
experimental/atomic experimental/barrier	experimental/future experimental/latch
范围 TS
<experimental/ranges/algorithm> <experimental/ranges/concepts> <experimental/ranges/functional>         <experimental/ranges/iterator>	<experimental/ranges/random> <experimental/ranges/tuple> <experimental/ranges/type_traits> <experimental/ranges/utility>
协程 TS
experimental/coroutine
网络 TS
experimental/buffer experimental/executor experimental/internet experimental/io_context	<experimental/net> experimental/netfwd experimental/socket experimental/timer
反射 TS
<experimental/reflect>

 

此头文件是范围库的一部分。

迭代器相关概念

定义于命名空间 std::experimental::ranges

迭代器概念

可读 (Readable)	指定可以通过应用运算符 * 来读取类型 (概念)
可写 (Writable)	指定可以将值写入迭代器引用的对象 (概念)
弱可递增 (WeaklyIncrementable)	指定 Semiregular 类型可以使用前缀和后缀递增运算符进行递增 (概念)
可递增 (Incrementable)	指定 WeaklyIncrementable 类型的递增操作是保持相等的，并且该类型是 EqualityComparable (概念)
迭代器 (Iterator)	指定类型的对象可以被递增和解引用 (概念)
哨位 (Sentinel)	指定类型的对象是 Iterator 类型的哨位 (概念)
带尺寸哨位 (SizedSentinel)	指定 - 运算符可以应用于迭代器和哨位，以常量时间计算它们的差值 (概念)
输入迭代器 (InputIterator)	指定类型是输入迭代器，即，可以读取其引用的值，并且可以进行前缀和后缀递增 (概念)
输出迭代器 (OutputIterator)	指定类型是给定值类型的输出迭代器，即，可以将该类型的值写入其中，并且可以进行前缀和后缀递增 (概念)
前向迭代器 (ForwardIterator)	指定 InputIterator 是前向迭代器，支持相等比较和多趟 (multi-pass) (概念)
双向迭代器 (BidirectionalIterator)	指定 ForwardIterator 是双向迭代器，支持向后移动 (概念)
随机访问迭代器 (RandomAccessIterator)	指定 BidirectionalIterator 是随机访问迭代器，支持常量时间步进和下标 (概念)

间接可调用概念

间接一元可调用 (IndirectUnaryInvocable)间接正则一元可调用 (IndirectRegularUnaryInvocable)	指定可调用类型可以使用解引用 Readable 类型的结果来调用 (概念)
间接一元谓词 (IndirectUnaryPredicate)	指定一个可调用对象，当使用解引用 Readable 类型的结果调用时，满足 Predicate (概念)
间接关系 (IndirectRelation)	指定一个可调用对象，当使用解引用一些 Readable 类型的结果调用时，满足 Relation (概念)
间接严格弱序 (IndirectStrictWeakOrder)	指定一个可调用对象，当使用解引用一些 Readable 类型的结果调用时，满足 StrictWeakOrder (概念)

常用算法要求

间接可移动 (IndirectlyMovable)	指定值可以从 Readable 类型移动到 Writable 类型 (概念)
间接可移动可存储 (IndirectlyMovableStorable)	指定值可以从 Readable 类型移动到 Writable 类型，并且移动可以通过中间对象执行 (概念)
间接可复制 (IndirectlyCopyable)	指定值可以从 Readable 类型复制到 Writable 类型 (概念)
间接可复制可存储 (IndirectlyCopyableStorable)	指定值可以从 Readable 类型复制到 Writable 类型，并且复制可以通过中间对象执行 (概念)
间接可交换 (IndirectlySwappable)	指定两个 Readable 类型引用的值可以被交换 (概念)
间接可比较 (IndirectlyComparable)	指定两个 Readable 类型引用的值可以被比较 (概念)
可置换 (Permutable)	指定就地重排元素的算法的通用要求 (概念)
可归并 (Mergeable)	指定通过复制元素将排序序列合并到输出序列的算法的要求 (概念)
可排序 (Sortable)	指定将序列置换为有序序列的算法的通用要求 (概念)

概念工具

间接结果类型 (indirect_result_of)	计算在解引用一组 Readable 类型的结果上调用可调用对象的结果 (类模板)
投影 (projected)	用于指定接受投影的算法约束的辅助模板 (类模板)

迭代器原语

迭代器工具

定义于命名空间 std::experimental::ranges
迭代器移动 (iter_move)	将解引用对象的结果转换为其关联的右值引用类型 (定制点对象)
迭代器交换 (iter_swap)	交换两个可解引用对象引用的值 (定制点对象)

迭代器特征

定义于命名空间 std::experimental::ranges
差值类型 (difference_type)	获取 WeaklyIncrementable 类型的差值类型 (类模板)
值类型 (value_type)	获取 Readable 类型的值类型 (类模板)
迭代器类别 (iterator_category)	获取输入迭代器类型的迭代器类别 (类模板)
迭代器特征 (iterator_traits)	兼容性特征类，用于收集迭代器的关联类型 (别名模板)
引用类型 (reference_t)右值引用类型 (rvalue_reference_t)迭代器公共引用类型 (iter_common_reference_t)	获取可解引用对象的关联引用类型 (别名模板)

迭代器类别标签

定义于命名空间 std::experimental::ranges
输入迭代器标签 (input_iterator_tag)输出迭代器标签 (output_iterator_tag)前向迭代器标签 (forward_iterator_tag)双向迭代器标签 (bidirectional_iterator_tag)随机访问迭代器标签 (random_access_iterator_tag)	用于指示迭代器类别的空类类型 (类)

std::iterator_traits 特化

定义于命名空间 std
std::iterator_traits<InputIterator>std::iterator_traits<OutputIterator>	为范围 TS 迭代器特化 std::iterator_traits (类模板特化)

迭代器操作

定义于命名空间 std::experimental::ranges
步进 (advance)	使迭代器步进给定距离 (函数模板)
距离 (distance)	返回迭代器和哨位之间，或范围的开始和结束之间的距离 (函数模板)
下一个 (next)	递增迭代器 (函数模板)
上一个 (prev)	递减迭代器 (函数模板)

迭代器适配器

定义于命名空间 std::experimental::ranges
反向迭代器 (reverse_iterator)	用于反向顺序遍历的迭代器适配器 (类模板)
后向插入迭代器 (back_insert_iterator)	用于在容器末尾插入的迭代器适配器 (类模板)
front_insert_iterator	用于在容器前端插入的迭代器适配器 (类模板)
insert_iterator	用于在容器中插入的迭代器适配器 (类模板)
move_iterator	解引用为右值引用的迭代器适配器 (类模板)
move_sentinel	用于 move_iterator 的哨位适配器 (类模板)
common_iterator	将迭代器-哨位对适配为通用迭代器类型，以便用于旧式算法 (类模板)
counted_iterator	迭代器适配器，用于跟踪其与起始位置的距离 (类模板)
default_sentinel	空哨位类型，用于知道其范围边界的迭代器类型 (类)
dangling	可能悬空的迭代器的包装器 (类模板)
safe_iterator_t	别名模板，用于使用 dangling 包装右值范围的迭代器类型 (别名模板)
unreachable	与任何迭代器一起使用的哨位类型，表示无限范围 (类)

流迭代器

定义于命名空间 std::experimental::ranges
istream_iterator	从 std::basic_istream 读取的输入迭代器 (类模板)
ostream_iterator	写入到 std::basic_ostream 的输出迭代器 (类模板)
istreambuf_iterator	从 std::basic_streambuf 读取的输入迭代器 (类模板)
ostreambuf_iterator	写入到 std::basic_streambuf 的输出迭代器 (类模板)

概要

namespace std { namespace experimental { namespace ranges { inline namespace v1 {
 
template <class T> concept bool /* dereferenceable */ // exposition only
  = requires(T& t) { {*t} -> auto&&; };
 
namespace {
  constexpr /* unspecified */ iter_move = /* unspecified */;
  constexpr /* unspecified */ iter_swap = /* unspecified */;
}
 
template <class> struct difference_type;
template <class T> using difference_type_t
  = typename difference_type<T>::type;
 
template <class> struct value_type;
template <class T> using value_type_t
  = typename value_type<T>::type;
 
template <class> struct iterator_category;
template <class T> using iterator_category_t
  = typename iterator_category<T>::type;
 
template </* dereferenceable */ T> using reference_t
  = decltype(*declval<T&>());
 
template </* dereferenceable */ T>
    requires /* see definition */ using rvalue_reference_t
  = decltype(ranges::iter_move(declval<T&>()));
 
template <class In>
concept bool Readable = /* see definition */;
 
template <class Out, class T>
concept bool Writable = /* see definition */;
 
template <class I>
concept bool WeaklyIncrementable = /* see definition */;
 
template <class I>
concept bool Incrementable = /* see definition */;
 
template <class I>
concept bool Iterator = /* see definition */;
 
template <class S, class I>
concept bool Sentinel = /* see definition */;
 
template <class S, class I>
  constexpr bool disable_sized_sentinel = false;
 
template <class S, class I>
concept bool SizedSentinel = /* see definition */;
 
template <class I>
concept bool InputIterator = /* see definition */;
 
template <class I>
concept bool OutputIterator = /* see definition */;
 
template <class I>
concept bool ForwardIterator = /* see definition */;
 
template <class I>
concept bool BidirectionalIterator = /* see definition */;
 
template <class I>
concept bool RandomAccessIterator = /* see definition */;
 
template <class F, class I>
concept bool IndirectUnaryInvocable = /* see definition */;
 
template <class F, class I>
concept bool IndirectRegularUnaryInvocable = /* see definition */;
 
template <class F, class I>
concept bool IndirectUnaryPredicate = /* see definition */;
 
template <class F, class I1, class I2 = I1>
concept bool IndirectRelation = /* see definition */;
 
template <class F, class I1, class I2 = I1>
concept bool IndirectStrictWeakOrder = /* see definition */;
 
template <class> struct indirect_result_of;
 
template <class F, class... Is>
  requires Invocable<F, reference_t<Is>...>
struct indirect_result_of<F(Is...)>;
 
template <class F>
using indirect_result_of_t
  = typename indirect_result_of<F>::type;
 
template <Readable I, IndirectRegularUnaryInvocable<I> Proj>
struct projected;
 
template <WeaklyIncrementable I, class Proj>
struct difference_type<projected<I, Proj>>;
 
template <class In, class Out>
concept bool IndirectlyMovable = /* see definition */;
 
template <class In, class Out>
concept bool IndirectlyMovableStorable = /* see definition */;
 
template <class In, class Out>
concept bool IndirectlyCopyable = /* see definition */;
 
template <class In, class Out>
concept bool IndirectlyCopyableStorable = /* see definition */;
 
template <class I1, class I2 = I1>
concept bool IndirectlySwappable = /* see definition */;
 
template <class I1, class I2, class R = equal_to<>, class P1 = identity,
    class P2 = identity>
concept bool IndirectlyComparable = /* see definition */;
 
template <class I>
concept bool Permutable = /* see definition */;
 
template <class I1, class I2, class Out,
    class R = less<>, class P1 = identity, class P2 = identity>
concept bool Mergeable = /* see definition */;
 
template <class I, class R = less<>, class P = identity>
concept bool Sortable = /* see definition */;
 
template <class Iterator> using iterator_traits = /* see definition */;
 
template <Readable T> using iter_common_reference_t
  = common_reference_t<reference_t<T>, value_type_t<T>&>;
 
struct output_iterator_tag { };
struct input_iterator_tag { };
struct forward_iterator_tag : input_iterator_tag { };
struct bidirectional_iterator_tag : forward_iterator_tag { };
struct random_access_iterator_tag : bidirectional_iterator_tag { };
 
namespace {
  constexpr /* unspecified */ advance = /* unspecified */;
  constexpr /* unspecified */ distance = /* unspecified */;
  constexpr /* unspecified */ next = /* unspecified */;
  constexpr /* unspecified */ prev = /* unspecified */;
}
 
template <BidirectionalIterator I> class reverse_iterator;
 
template <class I1, class I2>
    requires EqualityComparableWith<I1, I2>
  constexpr bool operator==(
    const reverse_iterator<I1>& x,
    const reverse_iterator<I2>& y);
template <class I1, class I2>
    requires EqualityComparableWith<I1, I2>
  constexpr bool operator!=(
    const reverse_iterator<I1>& x,
    const reverse_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator<(
    const reverse_iterator<I1>& x,
    const reverse_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator>(
    const reverse_iterator<I1>& x,
    const reverse_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator>=(
    const reverse_iterator<I1>& x,
    const reverse_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator<=(
    const reverse_iterator<I1>& x,
    const reverse_iterator<I2>& y);
 
template <class I1, class I2>
    requires SizedSentinel<I1, I2>
  constexpr difference_type_t<I2> operator-(
    const reverse_iterator<I1>& x,
    const reverse_iterator<I2>& y);
template <RandomAccessIterator I>
  constexpr reverse_iterator<I> operator+(
    difference_type_t<I> n,
    const reverse_iterator<I>& x);
 
template <BidirectionalIterator I>
constexpr reverse_iterator<I> make_reverse_iterator(I i);
 
template <class Container> class back_insert_iterator;
template <class Container>
  back_insert_iterator<Container> back_inserter(Container& x);
 
template <class Container> class front_insert_iterator;
template <class Container>
  front_insert_iterator<Container> front_inserter(Container& x);
 
template <class Container> class insert_iterator;
template <class Container>
  insert_iterator<Container> inserter(Container& x, iterator_t<Container> i);
 
template <InputIterator I> class move_iterator;
 
template <class I1, class I2>
    requires EqualityComparableWith<I1, I2>
  constexpr bool operator==(
    const move_iterator<I1>& x, const move_iterator<I2>& y);
template <class I1, class I2>
    requires EqualityComparableWith<I1, I2>
  constexpr bool operator!=(
    const move_iterator<I1>& x, const move_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator<(
    const move_iterator<I1>& x, const move_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator<=(
    const move_iterator<I1>& x, const move_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator>(
    const move_iterator<I1>& x, const move_iterator<I2>& y);
template <class I1, class I2>
    requires StrictTotallyOrderedWith<I1, I2>
  constexpr bool operator>=(
    const move_iterator<I1>& x, const move_iterator<I2>& y);
 
template <class I1, class I2>
    requires SizedSentinel<I1, I2>
  constexpr difference_type_t<I2> operator-(
    const move_iterator<I1>& x,
    const move_iterator<I2>& y);
template <RandomAccessIterator I>
  constexpr move_iterator<I> operator+(
    difference_type_t<I> n,
    const move_iterator<I>& x);
 
template <InputIterator I>
  constexpr move_iterator<I> make_move_iterator(I i);
 
template <Semiregular S> class move_sentinel;
 
template <class I, Sentinel<I> S>
  constexpr bool operator==(
    const move_iterator<I>& i, const move_sentinel<S>& s);
template <class I, Sentinel<I> S>
  constexpr bool operator==(
    const move_sentinel<S>& s, const move_iterator<I>& i);
template <class I, Sentinel<I> S>
  constexpr bool operator!=(
    const move_iterator<I>& i, const move_sentinel<S>& s);
template <class I, Sentinel<I> S>
  constexpr bool operator!=(
    const move_sentinel<S>& s, const move_iterator<I>& i);
 
template <class I, SizedSentinel<I> S>
  constexpr difference_type_t<I> operator-(
    const move_sentinel<S>& s, const move_iterator<I>& i);
template <class I, SizedSentinel<I> S>
  constexpr difference_type_t<I> operator-(
    const move_iterator<I>& i, const move_sentinel<S>& s);
 
template <Semiregular S>
  constexpr move_sentinel<S> make_move_sentinel(S s);
 
template <Iterator I, Sentinel<I> S>
  requires !Same<I, S>
class common_iterator;
 
template <Readable I, class S>
struct value_type<common_iterator<I, S>>;
 
template <InputIterator I, class S>
struct iterator_category<common_iterator<I, S>>;
 
template <ForwardIterator I, class S>
struct iterator_category<common_iterator<I, S>>;
 
template <class I1, class I2, Sentinel<I2> S1, Sentinel<I1> S2>
bool operator==(
  const common_iterator<I1, S1>& x, const common_iterator<I2, S2>& y);
template <class I1, class I2, Sentinel<I2> S1, Sentinel<I1> S2>
  requires EqualityComparableWith<I1, I2>
bool operator==(
  const common_iterator<I1, S1>& x, const common_iterator<I2, S2>& y);
template <class I1, class I2, Sentinel<I2> S1, Sentinel<I1> S2>
bool operator!=(
  const common_iterator<I1, S1>& x, const common_iterator<I2, S2>& y);
 
template <class I2, SizedSentinel<I2> I1, SizedSentinel<I2> S1, SizedSentinel<I1> S2>
difference_type_t<I2> operator-(
  const common_iterator<I1, S1>& x, const common_iterator<I2, S2>& y);
 
class default_sentinel;
 
template <Iterator I> class counted_iterator;
 
template <class I1, class I2>
    requires Common<I1, I2>
  constexpr bool operator==(
    const counted_iterator<I1>& x, const counted_iterator<I2>& y);
constexpr bool operator==(
  const counted_iterator<auto>& x, default_sentinel);
constexpr bool operator==(
  default_sentinel, const counted_iterator<auto>& x);
template <class I1, class I2>
    requires Common<I1, I2>
  constexpr bool operator!=(
    const counted_iterator<I1>& x, const counted_iterator<I2>& y);
constexpr bool operator!=(
  const counted_iterator<auto>& x, default_sentinel y);
constexpr bool operator!=(
  default_sentinel x, const counted_iterator<auto>& y);
template <class I1, class I2>
    requires Common<I1, I2>
  constexpr bool operator<(
    const counted_iterator<I1>& x, const counted_iterator<I2>& y);
template <class I1, class I2>
    requires Common<I1, I2>
  constexpr bool operator<=(
    const counted_iterator<I1>& x, const counted_iterator<I2>& y);
template <class I1, class I2>
    requires Common<I1, I2>
  constexpr bool operator>(
    const counted_iterator<I1>& x, const counted_iterator<I2>& y);
template <class I1, class I2>
    requires Common<I1, I2>
  constexpr bool operator>=(
    const counted_iterator<I1>& x, const counted_iterator<I2>& y);
 
template <class I1, class I2>
    requires Common<I1, I2>
  constexpr difference_type_t<I2> operator-(
    const counted_iterator<I1>& x, const counted_iterator<I2>& y);
template <class I>
  constexpr difference_type_t<I> operator-(
    const counted_iterator<I>& x, default_sentinel y);
template <class I>
  constexpr difference_type_t<I> operator-(
    default_sentinel x, const counted_iterator<I>& y);
template <RandomAccessIterator I>
  constexpr counted_iterator<I>
    operator+(difference_type_t<I> n, const counted_iterator<I>& x);
 
template <Iterator I>
  constexpr counted_iterator<I> make_counted_iterator(I i, difference_type_t<I> n);
 
class unreachable;
template <Iterator I>
  constexpr bool operator==(const I&, unreachable) noexcept;
template <Iterator I>
  constexpr bool operator==(unreachable, const I&) noexcept;
template <Iterator I>
  constexpr bool operator!=(const I&, unreachable) noexcept;
template <Iterator I>
  constexpr bool operator!=(unreachable, const I&) noexcept;
 
template <class T> class dangling;
 
template <class T, class CharT = char, class Traits = char_traits<CharT>,
    class Distance = ptrdiff_t>
  class istream_iterator;
 
template <class T, class CharT, class Traits, class Distance>
  bool operator==(const istream_iterator<T, CharT, Traits, Distance>& x,
    const istream_iterator<T, CharT, Traits, Distance>& y);
template <class T, class CharT, class Traits, class Distance>
  bool operator==(default_sentinel x,
    const istream_iterator<T, CharT, Traits, Distance>& y);
template <class T, class CharT, class Traits, class Distance>
  bool operator==(const istream_iterator<T, CharT, Traits, Distance>& x,
    default_sentinel y);
template <class T, class CharT, class Traits, class Distance>
  bool operator!=(const istream_iterator<T, CharT, Traits, Distance>& x,
    const istream_iterator<T, CharT, Traits, Distance>& y);
template <class T, class CharT, class Traits, class Distance>
  bool operator!=(default_sentinel x,
    const istream_iterator<T, CharT, Traits, Distance>& y);
template <class T, class CharT, class Traits, class Distance>
  bool operator!=(const istream_iterator<T, CharT, Traits, Distance>& x,
    default_sentinel y);
 
template <class T, class CharT = char, class Traits = char_traits<CharT>>
  class ostream_iterator;
 
template <class CharT, class Traits = char_traits<CharT> >
  class istreambuf_iterator;
 
template <class CharT, class Traits>
  bool operator==(const istreambuf_iterator<CharT, Traits>& a,
    const istreambuf_iterator<CharT, Traits>& b);
template <class CharT, class Traits>
  bool operator==(default_sentinel a,
    const istreambuf_iterator<CharT, Traits>& b);
template <class CharT, class Traits>
  bool operator==(const istreambuf_iterator<CharT, Traits>& a,
    default_sentinel b);
template <class CharT, class Traits>
  bool operator!=(const istreambuf_iterator<CharT, Traits>& a,
    const istreambuf_iterator<CharT, Traits>& b);
template <class CharT, class Traits>
  bool operator!=(default_sentinel a,
    const istreambuf_iterator<CharT, Traits>& b);
template <class CharT, class Traits>
  bool operator!=(const istreambuf_iterator<CharT, Traits>& a,
    default_sentinel b);
 
template <class CharT, class Traits = char_traits<CharT> >
  class ostreambuf_iterator;
 
}}}}
 
namespace std {
  template <experimental::ranges::Iterator Out>
    struct iterator_traits<Out>;
  template <experimental::ranges::InputIterator In>
    struct iterator_traits<In>;
  template <experimental::ranges::InputIterator In>
      requires experimental::ranges::Sentinel<In, In>
    struct iterator_traits;
}