process.h

//
// Copyright 2019 - 2024 (C). Alex Robenko. All rights reserved.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
#pragma once
 
#include <type_traits>
 
#include "comms/Message.h"
#include "comms/details/detect.h"
 
namespace  comms
{
 
namespace details
{
 
template <typename T>
using ProcessMsgDecayType = typename std::decay<T>::type;
 
template <bool TIsMessage, bool TIsMsgPtr>
struct ProcessMsgIdRetrieveHelper
{
    template <typename T>
    using Type = void;
};
 
template <>
struct ProcessMsgIdRetrieveHelper<true, false>
{
    template <typename T>
    using Type = comms::MessageIdType<T>;
};
 
template <>
struct ProcessMsgIdRetrieveHelper<false, true>
{
private:
    template <typename T>
    using ElementType = typename T::element_type;
public:
    template <typename T>
    using Type =
        typename ProcessMsgIdRetrieveHelper<comms::isMessage<ElementType<T> >(),  hasElementType<ElementType<T> >()>::
            template Type<ElementType<T> >;
};
 
template <typename T>
using ProcessMsgIdType =
    typename ProcessMsgIdRetrieveHelper<comms::isMessage<ProcessMsgDecayType<T> >(), hasElementType<ProcessMsgDecayType<T> >()>::
        template Type<ProcessMsgDecayType<T> >;
 
 
template <bool TIsMessage, bool TIsMsgPtr>
struct ProcessMsgCastToMsgObjHelper;
 
template <>
struct ProcessMsgCastToMsgObjHelper<true, false>
{
    template <typename T>
    static auto cast(T& msg) -> decltype(msg)
    {
        return msg;
    }
};
 
template <>
struct ProcessMsgCastToMsgObjHelper<false, true>
{
    template <typename T>
    static auto cast(T& msg) -> decltype(*msg)
    {
        return *msg;
    }
};
 
template <typename T>
using ProcessMsgCastParamIsMessage = 
    std::integral_constant<
        bool,
        isMessage<ProcessMsgDecayType<T> >()
    >;
 
template <typename T>
using ProcessMsgCastParamIsMsgPtr = 
    std::integral_constant<
        bool,
        hasElementType<ProcessMsgDecayType<T> >()
    >;    
 
template <typename T>
auto processMsgCastToMsgObj(T& msg) ->
    decltype(ProcessMsgCastToMsgObjHelper<ProcessMsgCastParamIsMessage<T>::value, ProcessMsgCastParamIsMsgPtr<T>::value>::cast(msg))
{
    return ProcessMsgCastToMsgObjHelper<ProcessMsgCastParamIsMessage<T>::value, ProcessMsgCastParamIsMsgPtr<T>::value>::cast(msg);
}
 
} // namespace details
 
} // namespace  comms