标准库头文件 <concepts>

此头文件是概念库的一部分。

概念
核心语言概念
same_as (C++20)	指定一个类型与另一类型相同 (概念)
derived_from (C++20)	指定一个类型派生自另一类型 (概念)
convertible_to (C++20)	指定一个类型能隐式转换成另一类型 (概念)
common_reference_with (C++20)	指定两个类型共有一个公共引用类型 (概念)
common_with (C++20)	指定两个类型共有一个公共类型 (概念)
integral (C++20)	指定类型为整型类型 (概念)
signed_integral (C++20)	指定类型为有符号的整型类型 (概念)
unsigned_integral (C++20)	指定类型为无符号的整型类型 (概念)
floating_point (C++20)	指定类型为浮点类型 (概念)
assignable_from (C++20)	指定一个类型能从另一类型赋值 (概念)
swappableswappable_with (C++20)	指定一个类型能进行交换，或两个类型能彼此交换 (概念)
destructible (C++20)	指定能销毁该类型的对象 (概念)
constructible_from (C++20)	指定该类型的变量能从一组实参类型进行构造，或绑定到一组实参类型 (概念)
default_initializable (C++20)	指定能默认构造一个类型的对象 (概念)
move_constructible (C++20)	指定能移动构造一个类型的对象 (概念)
copy_constructible (C++20)	指定能复制构造和移动构造一个类型的对象 (概念)
比较概念
equality_comparableequality_comparable_with (C++20)	指定运算符 == 为等价关系 (概念)
totally_orderedtotally_ordered_with (C++20)	指定比较运算符在该类型上产生全序 (概念)
对象概念
movable (C++20)	指定能移动及交换一个类型的对象 (概念)
copyable (C++20)	指定能复制、移动及交换一个类型的对象 (概念)
semiregular (C++20)	指定能赋值、移动、交换及默认构造一个类型的对象 (概念)
regular (C++20)	指定类型为正则，即它既为 `semiregular` 亦为 `equality_comparable` (概念)
可调用概念
invocableregular_invocable (C++20)	指定能以给定的一组实参类型调用的可调用类型 (概念)
predicate (C++20)	指定可调用类型为布尔谓词 (概念)
relation (C++20)	指定可调用类型为二元关系 (概念)
equivalence_relation (C++20)	指定 `relation` 施加等价关系 (概念)
strict_weak_order (C++20)	指定一个 `relation` 所强加的是严格弱序 (概念)
定制点对象
ranges::swap (C++20)	交换两个对象的值 (定制点对象)

概要

namespace std {
  // 语言相关概念
  // 概念 same_as
  template<class T, class U>
    concept same_as = /* 见描述 */;
 
  // 概念 derived_from
  template<class Derived, class Base>
    concept derived_from = /* 见描述 */;
 
  // 概念 convertible_to
  template<class From, class To>
    concept convertible_to = /* 见描述 */;
 
  // 概念 common_reference_with
  template<class T, class U>
    concept common_reference_with = /* 见描述 */;
 
  // 概念 common_with
  template<class T, class U>
    concept common_with = /* 见描述 */;
 
  // 算术概念
  template<class T>
    concept integral = /* 见描述 */;
  template<class T>
    concept signed_integral = /* 见描述 */;
  template<class T>
    concept unsigned_integral = /* 见描述 */;
  template<class T>
    concept floating_point = /* 见描述 */;
 
  // 概念 assignable_from
  template<class LHS, class RHS>
    concept assignable_from = /* 见描述 */;
 
  // 概念 swappable
  namespace ranges {
    inline namespace /* 未指明 */ {
      inline constexpr /* 未指明 */ swap = /* 未指明 */;
    }
  }
  template<class T>
    concept swappable = /* 见描述 */;
  template<class T, class U>
    concept swappable_with = /* 见描述 */;
 
  // 概念 destructible
  template<class T>
    concept destructible = /* 见描述 */;
 
  // 概念 constructible_from
  template<class T, class... Args>
    concept constructible_from = /* 见描述 */;
 
  // 概念 default_initializable
  template<class T>
    concept default_initializable = /* 见描述 */;
 
  // 概念 move_constructible
  template<class T>
    concept move_constructible = /* 见描述 */;
 
  // 概念 copy_constructible
  template<class T>
    concept copy_constructible = /* 见描述 */;
 
  // 比较概念
  // 概念 equality_comparable
  template<class T>
    concept equality_comparable = /* 见描述 */;
  template<class T, class U>
    concept equality_comparable_with = /* 见描述 */;
 
  // 概念 totally_ordered
  template<class T>
    concept totally_ordered = /* 见描述 */;
  template<class T, class U>
    concept totally_ordered_with = /* 见描述 */;
 
  // 对象概念
  template<class T>
    concept movable = /* 见描述 */;
  template<class T>
    concept copyable = /* 见描述 */;
  template<class T>
    concept semiregular = /* 见描述 */;
  template<class T>
    concept regular = /* 见描述 */;
 
  // 可调用概念
  // 概念 invocable
  template<class F, class... Args>
    concept invocable = /* 见描述 */;
 
  // 概念 regular_invocable
  template<class F, class... Args>
    concept regular_invocable = /* 见描述 */;
 
  // 概念 predicate
  template<class F, class... Args>
    concept predicate = /* 见描述 */;
 
  // 概念 relation
  template<class R, class T, class U>
    concept relation = /* 见描述 */;
 
  // 概念 equivalence_relation
  template<class R, class T, class U>
    concept equivalence_relation = /* 见描述 */;
 
  // 概念 strict_weak_order
  template<class R, class T, class U>
    concept strict_weak_order = /* 见描述 */;
}

概念 `same_as`

template<class T, class U>
  concept __SameImpl = is_same_v<T, U>;  // 仅为阐释
 
template<class T, class U>
  concept same_as = __SameImpl<T, U> && __SameImpl<U, T>;

概念 `derived_from`

template<class Derived, class Base>
  concept derived_from =
    is_base_of_v<Base, Derived> &&
    is_convertible_v<const volatile Derived*, const volatile Base*>;

概念 `convertible_to`

template<class From, class To>
  concept convertible_to =
    is_convertible_v<From, To> &&
    requires(From (&f)()) {
      static_cast<To>(f());
    };

概念 `common_reference_with`

template<class T, class U>
  concept common_reference_with =
    same_as<common_reference_t<T, U>, common_reference_t<U, T>> &&
    convertible_to<T, common_reference_t<T, U>> &&
    convertible_to<U, common_reference_t<T, U>>;

概念 `common_with`

template<class T, class U>
  concept common_with =
    same_as<common_type_t<T, U>, common_type_t<U, T>> &&
    requires {
      static_cast<common_type_t<T, U>>(declval<T>());
      static_cast<common_type_t<T, U>>(declval<U>());
    } &&
    common_reference_with<
      add_lvalue_reference_t<const T>,
      add_lvalue_reference_t<const U>> &&
    common_reference_with<
      add_lvalue_reference_t<common_type_t<T, U>>,
      common_reference_t<
        add_lvalue_reference_t<const T>,
        add_lvalue_reference_t<const U>>>;

概念 `integral`

template<class T>
  concept integral = is_integral_v<T>;

概念 `signed_integral`

template<class T>
  concept signed_integral = integral<T> && is_signed_v<T>;

概念 `unsigned_integral`

template<class T>
  concept unsigned_integral = integral<T> && !signed_integral<T>;

概念 `floating_point`

template<class T>
  concept floating_point = is_floating_point_v<T>;

概念 `assignable_from`

template<class LHS, class RHS>
  concept assignable_from =
    is_lvalue_reference_v<LHS> &&
    common_reference_with<
      const remove_reference_t<LHS>&,
      const remove_reference_t<RHS>&> &&
    requires(LHS lhs, RHS&& rhs) {
      { lhs = std::forward<RHS>(rhs) } -> same_as<LHS>;

概念 `swappable`

template<class T>
  concept swappable = requires(T& a, T& b) { ranges::swap(a, b); };

概念 `swappable_with`

template<class T, class U>
  concept swappable_with =
    common_reference_with<const remove_reference_t<T>&, const remove_reference_t<U>&> &&
    requires(T&& t, U&& u) {
      ranges::swap(std::forward<T>(t), std::forward<T>(t));
      ranges::swap(std::forward<U>(u), std::forward<U>(u));
      ranges::swap(std::forward<T>(t), std::forward<U>(u));
      ranges::swap(std::forward<U>(u), std::forward<T>(t));
    };

概念 `destructible`

template<class T>
  concept destructible = is_nothrow_destructible_v<T>;

概念 `constructible_from`

template<class T, class... Args>
  concept constructible_from = destructible<T> && is_constructible_v<T, Args...>;

概念 `default_initializable`

template<class T>
  inline constexpr bool __is_default_initializable = /* 见描述 */;  // 仅用于阐释
 
template<class T>
  concept default_initializable = constructible_from<T> &&
                                  requires{ T{}; } &&
                                  __is_default_initializable<T>;

概念 `move_constructible`

template<class T>
  concept move_constructible = constructible_from<T, T> && convertible_to<T, T>;

概念 `copy_constructible`

template<class T>
  concept copy_constructible =
    move_constructible<T> &&
    constructible_from<T, T&> && convertible_to<T&, T> &&
    constructible_from<T, const T&> && convertible_to<const T&, T> &&
    constructible_from<T, const T> && convertible_to<const T, T>;

概念 `equality_comparable`

template<class T, class U>
  concept __WeaklyEqualityComparableWith = // 仅为阐释
    requires(const remove_reference_t<T>& t,
             const remove_reference_t<U>& u) {
      { t == u } -> boolean-testable;
      { t != u } -> boolean-testable;
      { u == t } -> boolean-testable;
      { u != t } -> boolean-testable;
    };
 
template<class T>
  concept equality_comparable = __WeaklyEqualityComparableWith<T, T>;

概念 `equality_comparable_with`

template<class T, class U>
  concept equality_comparable_with =
    equality_comparable<T> && equality_comparable<U> &&
    common_reference_with<const remove_reference_t<T>&, const remove_reference_t<U>&> &&
    equality_comparable<
      common_reference_t<
        const remove_reference_t<T>&,
        const remove_reference_t<U>&>> &&
    __WeaklyEqualityComparableWith<T, U>;

概念 `totally_ordered`

template<class T>
  concept totally_ordered =
    equality_comparable<T> &&
    requires(const remove_reference_t<T>& a,
             const remove_reference_t<T>& b) {
      { a <  b } -> boolean-testable;
      { a >  b } -> boolean-testable;
      { a <= b } -> boolean-testable;
      { a >= b } -> boolean-testable;
    };

概念 `totally_ordered_with`

template<class T, class U>
  concept totally_ordered_with =
    totally_ordered<T> && totally_ordered<U> &&
    common_reference_with<const remove_reference_t<T>&, const remove_reference_t<U>&> &&
    totally_ordered<
      common_reference_t<
        const remove_reference_t<T>&,
        const remove_reference_t<U>&>> &&
    equality_comparable_with<T, U> &&
    requires(const remove_reference_t<T>& t,
             const remove_reference_t<U>& u) {
      { t <  u } -> boolean-testable;
      { t >  u } -> boolean-testable;
      { t <= u } -> boolean-testable;
      { t >= u } -> boolean-testable;
      { u <  t } -> boolean-testable;
      { u >  t } -> boolean-testable;
      { u <= t } -> boolean-testable;
      { u >= t } -> boolean-testable;
    };

概念 `movable`

template<class T>
  concept movable = is_object_v<T> && move_constructible<T> &&
                    assignable_from<T&, T> && swappable<T>;

概念 `copyable`

template<class T>
  concept copyable = copy_constructible<T> && movable<T> && assignable_from<T&, T&> &&
                     assignable_from<T&, const T&> && assignable_from<T&, const T>;

概念 `semiregular`

template<class T>
  concept semiregular = copyable<T> && default_initializable<T>;

概念 `regular`

template<class T>
  concept regular = semiregular<T> && equality_comparable<T>;

概念 `invocable`

template<class F, class... Args>
  concept invocable = requires(F&& f, Args&&... args) {
    invoke(std::forward<F>(f), std::forward<Args>(args)...);
      // 不要求保持相等性
  };

概念 `regular_invocable`

template<class F, class... Args>
  concept regular_invocable = invocable<F, Args...>;

概念 `predicate`

template<class F, class... Args>
  concept predicate =
    regular_invocable<F, Args...> && boolean-testable<invoke_result_t<F, Args...>>;

概念 `relation`

template<class R, class T, class U>
  concept relation =
    predicate<R, T, T> && predicate<R, U, U> &&
    predicate<R, T, U> && predicate<R, U, T>;

概念 `equivalence_relation`

template<class R, class T, class U>
  concept equivalence_relation = relation<R, T, U>;

概念 `strict_weak_order`

template<class R, class T, class U>
  concept strict_weak_order = relation<R, T, U>;

语言
标准库头文件
自立与有宿主实现
具名要求
语言支持库
概念库 (C++20)
诊断库
工具库
字符串库
容器库
迭代器库
范围库 (C++20)
算法库
数值库
本地化库
输入/输出库
文件系统库 (C++17)
正则表达式库 (C++11)
原子操作库 (C++11)
线程支持库 (C++11)
技术规范

标准库头文件 <concepts>

概念

核心语言概念

比较概念

对象概念

可调用概念

定制点对象

概要

概念 same_as

概念 derived_from

概念 convertible_to

概念 common_reference_with

概念 common_with

概念 integral

概念 signed_integral

概念 unsigned_integral

概念 floating_point

概念 assignable_from

概念 swappable

概念 swappable_with

概念 destructible

概念 constructible_from

概念 default_initializable

概念 move_constructible

概念 copy_constructible

概念 equality_comparable

概念 equality_comparable_with

概念 totally_ordered

概念 totally_ordered_with

概念 movable

概念 copyable

概念 semiregular

概念 regular

概念 invocable

概念 regular_invocable

概念 predicate

概念 relation

概念 equivalence_relation

概念 strict_weak_order

概念 `same_as`

概念 `derived_from`

概念 `convertible_to`

概念 `common_reference_with`

概念 `common_with`

概念 `integral`

概念 `signed_integral`

概念 `unsigned_integral`

概念 `floating_point`

概念 `assignable_from`

概念 `swappable`

概念 `swappable_with`

概念 `destructible`

概念 `constructible_from`

概念 `default_initializable`

概念 `move_constructible`

概念 `copy_constructible`

概念 `equality_comparable`

概念 `equality_comparable_with`

概念 `totally_ordered`

概念 `totally_ordered_with`

概念 `movable`

概念 `copyable`

概念 `semiregular`

概念 `regular`

概念 `invocable`

概念 `regular_invocable`

概念 `predicate`

概念 `relation`

概念 `equivalence_relation`

概念 `strict_weak_order`