shared_state.hpp

// Copyright Take Vos 2022.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "observed.hpp"
#include "observer_intf.hpp"
#include "../utility/utility.hpp"
#include "../concurrency/thread.hpp" // XXX #616
#include "../macros.hpp"
#include <memory>
 
hi_export_module(hikogui.observer : shared_state);
 
hi_export namespace hi::inline v1 {
 
template<typename T>
class shared_state {
public:
    using value_type = T;
 
    ~shared_state() = default;
    constexpr shared_state(shared_state const&) noexcept = default;
    constexpr shared_state(shared_state&&) noexcept = default;
    constexpr shared_state& operator=(shared_state const&) noexcept = default;
    constexpr shared_state& operator=(shared_state&&) noexcept = default;
 
    template<typename... Args>
    constexpr shared_state(Args&&...args) noexcept :
        _pimpl(std::make_shared<observed<value_type>>(std::forward<Args>(args)...))
    {
    }
 
    observer<value_type> observer() const & noexcept
    {
        return ::hi::observer<value_type>(_pimpl);
    }
 
    // clang-format off
    [[nodiscard]] auto sub(auto const& index) const& noexcept
        requires requires { observer().sub(index); }
    {
        return observer().sub(index);
    }
    // clang-format on
 
    template<fixed_string Name>
    [[nodiscard]] auto sub() const& noexcept
    {
        return observer().template sub<Name>();
    }
 
private:
    std::shared_ptr<observed<value_type>> _pimpl;
};
 
}