Docs4dev
Docs
cpp / latest / iterator / indirectly_readable.html

std::indirectly_readable

Defined in header <iterator> 
template< class In >
    concept __IndirectlyReadableImpl =
        requires(const In in) {
            typename std::iter_value_t<In>;
            typename std::iter_reference_t<In>;
            typename std::iter_rvalue_reference_t<In>;
            { *in } -> std::same_as<std::iter_reference_t<In>>;
            { ranges::iter_move(in) } -> std::same_as<std::iter_rvalue_reference_t<In>>;
        } &&
        std::common_reference_with<
            std::iter_reference_t<In>&&, std::iter_value_t<In>&
        > &&
        std::common_reference_with<
            std::iter_reference_t<In>&&, std::iter_rvalue_reference_t<In>&&
        > &&
        std::common_reference_with<
            std::iter_rvalue_reference_t<In>&&, const std::iter_value_t<In>&
        >;
 (exposition only*) 
template< class In >
    concept indirectly_readable =
        __IndirectlyReadableImpl<std::remove_cvref_t<In>>;
 (since C++20)

The concept indirectly_readable is modeled by types that are readable by applying operator*, such as pointers, smart pointers, and input iterators.

Semantic requirements

Given a value i of type I, I models indirectly_readable only if all concepts it subsumes are modeled and the expression *i is equality-preserving.

Equality preservation

Expressions declared in requires expressions of the standard library concepts are required to be equality-preserving (except where stated otherwise).

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/iterator/indirectly_readable