std::ranges::iter_swap - cppreference.com (original) (raw)

| Defined in header | | | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | ------------------------------------------ | | namespace ranges { inline namespace /* unspecified */ { inline constexpr /* unspecified */ iter_swap = /* unspecified */; } } | | (since C++20) (customization point object) | | Call signature | | | | template< class I1, class I2 > constexpr void iter_swap( I1&& i1, I2&& i2 ) noexcept(/* see below */); | | (since C++20) | | Helper function | | | | template< class X, class Y > constexpr std::iter_value_t<X> iter-exchange-move( X&& x, Y&& y ) noexcept(noexcept(std::iter_value_t<X>(std::ranges::iter_move(x))) && noexcept(*x = std::ranges::iter_move(y))); | | (exposition only*) |

Swaps values denoted by two iterators.

The effect of the exposition-only helper function _iter-exchange-move_ is equivalent to

ranges::iter_swap(i1, i2) is expression-equivalent to:

  1. (void)iter_swap(i1, i2), if i1 or i2 has a class or enumeration type and the expression is well-formed, where the overload resolution of iter_swap is performed with the additional candidate void iter_swap(auto, auto) = delete;[1], excluding std::ranges::iter_swap itself.
    • If the selected overload does not exchange the value denoted by i1 and i2, the program is ill-formed, no diagnostic required.
  2. Otherwise, ranges::swap(*i1, *i2) if both I1 and I2 model indirectly_readable and if std::iter_reference_t<I1> and std::iter_reference_t<I2> model swappable_with.
  3. Otherwise, (void)(*i1 = _iter-exchange-move_(i2, i1)), if std::indirectly_movable_storable<I1, I2> and std::indirectly_movable_storable<I2, I1> are both modeled, except that i1 is only evaluated once.
  4. Otherwise, ranges::iter_swap(i1, i2) is ill-formed, which can result in substitution failure when ranges::iter_swap(i1, i2) appears in the immediate context of a template instantiation.
  5. ↑ This precludes calling unconstrained std::iter_swap.

Customization point objects

The name ranges::iter_swap denotes a customization point object, which is a const function object of a literal semiregular class type. See CustomizationPointObject for details.

[edit] Example

[edit] See also

| | swaps the objects pointed to by two adjusted underlying iterators (function template) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | | swaps the objects pointed to by two underlying iterators (function template) [edit] | | | swaps the elements pointed to by two iterators (function template) [edit] |