as_const_view.h

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#pragma once
 
#include "di/container/concepts/prelude.h"
#include "di/container/concepts/simple_view.h"
#include "di/container/interface/cbegin.h"
#include "di/container/interface/cend.h"
#include "di/container/meta/as_view.h"
#include "di/container/meta/enable_borrowed_container.h"
#include "di/container/view/view_interface.h"
#include "di/meta/operations.h"
#include "di/util/move.h"
 
namespace di::container {
template<concepts::View View>
requires(concepts::InputContainer<View>)
class AsConstView
    : public ViewInterface<AsConstView<View>>
    , public meta::EnableBorrowedContainer<AsConstView<View>, concepts::BorrowedContainer<View>> {
public:
    constexpr AsConstView()
    requires(concepts::DefaultInitializable<View>)
    = default;
 
    constexpr explicit AsConstView(View view) : m_view(util::move(view)) {}
 
    constexpr auto base() const& -> View
    requires(concepts::CopyConstructible<View>)
    {
        return m_view;
    }
 
    constexpr auto base() && -> View { return util::move(m_view); }
 
    constexpr auto begin() const
    requires(!concepts::SimpleView<View>)
    {
        return container::cbegin(m_view);
    }
 
    constexpr auto begin() const
    requires(concepts::Container<View const>)
    {
        return container::cbegin(m_view);
    }
 
    constexpr auto end() const
    requires(!concepts::SimpleView<View>)
    {
        return container::cend(m_view);
    }
 
    constexpr auto end() const
    requires(concepts::Container<View const>)
    {
        return container::cend(m_view);
    }
 
    constexpr auto size()
    requires(concepts::SizedContainer<View>)
    {
        return container::size(m_view);
    }
 
    constexpr auto size() const
    requires(concepts::SizedContainer<View const>)
    {
        return container::size(m_view);
    }
 
private:
    View m_view;
};
 
template<typename Con>
AsConstView(Con&&) -> AsConstView<meta::AsView<Con>>;
}