indirectly-binary-left-foldable, indirectly-binary-right-foldable
template< class F, class T, class I >
concept /*indirectly-binary-left-foldable*/ =
std::copy_constructible<F> &&
std::indirectly_readable<I> &&
std::invocable<F&, T, std::iter_reference_t<I>> &&
std::convertible_to<std::invoke_result_t
<F&, T, std::iter_reference_t<I>>,
std::decay_t<std::invoke_result_t<F&, T, std::iter_reference_t<I>>>> &&
/*indirectly-binary-left-foldable-impl*/
<F, T, I,
std::decay_t<std::invoke_result_t<F&, T, std::iter_reference_t<I>>>>;
| (1) |
(since C++23) (exposition only*) |
template< class F, class T, class I >
concept /*indirectly-binary-right-foldable*/ =
/*indirectly-binary-left-foldable*/</*flipped*/<F>, T, I>;
| (2) |
(since C++23) (exposition only*) |
| Helper concepts | ||
template< class F, class T, class I, class U >
concept /*indirectly-binary-left-foldable-impl*/ =
std::movable<T> &&
std::movable<U> &&
std::convertible_to<T, U> &&
std::invocable<F&, U, std::iter_reference_t<I>> &&
std::assignable_from
<U&, std::invoke_result_t<F&, U, std::iter_reference_t<I>>>;
| (3) |
(since C++23) (exposition only*) |
template< class F >
class /*flipped*/
{
F f; // exposition only
public:
template< class T, class U >
requires std::invocable<F&, U, T>
std::invoke_result_t<F&, U, T> operator()( T&&, U&& );
};
| (4) |
(since C++23) (exposition only*) |
1) The exposition-only concept
indirectly-binary-left-foldable is used by left-folding algorithms to constrain the function object template parameter.
2) The exposition-only concept
indirectly-binary-right-foldable is used by right-folding algorithms to constrain the function object template parameter.See also
|
(C++23) | left-folds a range of elements (algorithm function object) |
|
(C++23) | left-folds a range of elements, and returns a pair (iterator, value) (algorithm function object) |
|
(C++23) | left-folds a range of elements using the first element as an initial value (algorithm function object) |
|
(C++23) | left-folds a range of elements using the first element as an initial value, and returns a pair (iterator, optional) (algorithm function object) |
|
(C++23) | right-folds a range of elements (algorithm function object) |
|
(C++23) | right-folds a range of elements using the last element as an initial value (algorithm function object) |
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