viewable_container.h

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#pragma once
 
#include "di/container/concepts/container.h"
#include "di/container/concepts/view.h"
#include "di/meta/core.h"
#include "di/meta/language.h"
#include "di/meta/operations.h"
 
namespace di::concepts {
// Any View is considered viewable, if and only if the View can be constructed from T.
// Non-views can be viewable, if they are either an lvalue, or they are movable (into the view), with
// the exception of std::initializer_list, which does not own its underlying values.
template<typename T>
concept ViewableContainer =
    Container<T> && ((View<meta::RemoveCVRef<T>> && ConstructibleFrom<meta::RemoveCVRef<T>, T>) ||
                     (!View<meta::RemoveCVRef<T>> &&
                      (LValueReference<T> || (Movable<meta::RemoveReference<T>> && !InitializerList<T>) )));
}