Commit 613a6ff7 authored by Ronan's avatar Ronan

feat(core): add a private-access file to access private data

parent 72bc4fec
/*
* private-access.h
* Copyright (C) 2017 Belledonne Communications SARL
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
// =============================================================================
// Tools to get/set private data of Cpp objects.
//
// See: https://bloglitb.blogspot.fr/2011/12/access-to-private-members-safer.html
// See: http://en.cppreference.com/w/cpp/language/adl
// See: http://en.cppreference.com/w/cpp/language/friend
// =============================================================================
#ifndef _PRIVATE_ACCESS_H_
#define _PRIVATE_ACCESS_H_
#include <type_traits>
#define L_INTERNAL_STRUCT_L_ATTR_GET(CLASS, ATTR_NAME) AttrGet ## _ ## CLASS ## _ ## ATTR_NAME
#define L_INTERNAL_STRUCT_ATTR_SPY(ATTR_NAME) AttrSpy ## _ ## ATTR_NAME
#define L_ENABLE_ATTR_ACCESS(CLASS, ATTR_TYPE, ATTR_NAME) \
template<typename AttrSpy, ATTR_TYPE CLASS::*Attr> \
struct L_INTERNAL_STRUCT_L_ATTR_GET(CLASS, ATTR_NAME) { \
friend constexpr ATTR_TYPE (CLASS::*get(AttrSpy *)) { \
return Attr; \
} \
}; \
template<typename T> \
struct L_INTERNAL_STRUCT_ATTR_SPY(ATTR_NAME); \
template<> \
struct L_INTERNAL_STRUCT_ATTR_SPY(ATTR_NAME)<CLASS> { \
friend constexpr ATTR_TYPE (CLASS::*get(L_INTERNAL_STRUCT_ATTR_SPY(ATTR_NAME)<CLASS> *)); \
}; \
template struct L_INTERNAL_STRUCT_L_ATTR_GET(CLASS, ATTR_NAME)< \
L_INTERNAL_STRUCT_ATTR_SPY(ATTR_NAME)<CLASS>, \
&CLASS::ATTR_NAME \
>;
// Warning: Allow to modify const data.
// Returns a ref to `ATTR_NAME`.
#define L_ATTR_GET(OBJECT, ATTR_NAME) \
(const_cast<std::remove_const<decltype(OBJECT)>::type &>(OBJECT)).*get( \
static_cast<L_INTERNAL_STRUCT_ATTR_SPY(ATTR_NAME)<std::decay<decltype(OBJECT)>::type> *>(nullptr) \
)
#endif // ifndef _PRIVATE_ACCESS_H_
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