tdlight/td/tl/TlObject.h

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
/**
* \file
* Contains the declarations of a base class for all TL-objects and some helper methods
*/
#include <cstdint>
#include <memory>
#include <string>
#include <utility>
namespace td {
class TlStorerCalcLength;
class TlStorerUnsafe;
class TlStorerToString;
/**
* This class is a base class for all TDLib TL-objects.
*/
class TlObject {
public:
/**
* Returns an identifier, uniquely determining the TL-type of the object.
*/
virtual std::int32_t get_id() const = 0;
/**
* Appends the object to the storer serializing object, a buffer of fixed length.
* \param[in] s Storer to which the object will be appended.
*/
virtual void store(TlStorerUnsafe &s) const {
}
/**
* Appends the object to the storer, calculating the TL-length of the serialized object.
* \param[in] s Storer to which the object will be appended.
*/
virtual void store(TlStorerCalcLength &s) const {
}
/**
* Helper function for the to_string method. Appends a string representation of the object to the storer.
* \param[in] s Storer to which the object string representation will be appended.
* \param[in] field_name Object field_name if applicable.
*/
virtual void store(TlStorerToString &s, const char *field_name) const = 0;
/**
* Default constructor.
*/
TlObject() = default;
/**
* Deleted copy constructor.
*/
TlObject(const TlObject &) = delete;
/**
* Deleted copy assignment operator.
*/
TlObject &operator=(const TlObject &) = delete;
/**
* Default move constructor.
*/
TlObject(TlObject &&) = default;
/**
* Default move assignment operator.
*/
TlObject &operator=(TlObject &&) = default;
/**
* Virtual destructor.
*/
virtual ~TlObject() = default;
};
/**
* A smart wrapper to store a pointer to a TL-object.
*/
template <class Type>
using tl_object_ptr = std::unique_ptr<Type>;
/**
* A function to create a dynamically allocated TL-object. Can be treated as an analogue of std::make_unique.
* Usage example:
* \code
* auto get_authorization_state_request = td::make_tl_object<td::td_api::getAuthorizationState>();
* auto send_message_request = td::make_tl_object<td::td_api::sendMessage>(chat_id, 0, false, false, nullptr,
* td::make_tl_object<td::td_api::inputMessageText>("Hello, world!!!", false, true, {}, nullptr));
* \endcode
*
* \tparam Type Type of the TL-object to construct.
* \param[in] args Arguments to pass to the object constructor.
* \return Wrapped pointer to the created TL-object.
*/
template <class Type, class... Args>
tl_object_ptr<Type> make_tl_object(Args &&... args) {
return tl_object_ptr<Type>(new Type(std::forward<Args>(args)...));
}
/**
* A function to downcast a wrapped pointer to a TL-object to a pointer to its subclass.
* Casting an object to an incorrect type will lead to undefined behaviour.
* Examples of usage:
* \code
* td::tl_object_ptr<td::td_api::callState> call_state = ...;
* switch (call_state->get_id()) {
* case td::td_api::callStatePending::ID: {
* auto state = td::move_tl_object_as<td::td_api::callStatePending>(call_state);
* // use state
* break;
* }
* case td::td_api::callStateExchangingKeys::ID: {
* // no additional fields, so cast isn't needed
* break;
* }
* case td::td_api::callStateReady::ID: {
* auto state = td::move_tl_object_as<td::td_api::callStateReady>(call_state);
* // use state
* break;
* }
* case td::td_api::callStateHangingUp::ID: {
* // no additional fields, so cast isn't needed
* break;
* }
* case td::td_api::callStateDiscarded::ID: {
* auto state = td::move_tl_object_as<td::td_api::callStateDiscarded>(call_state);
* // use state
* break;
* }
* case td::td_api::callStateError::ID: {
* auto state = td::move_tl_object_as<td::td_api::callStateError>(call_state);
* // use state
* break;
* }
* default:
* assert(false);
* }
* \endcode
*
* \tparam ToT Type of a TL-object to move to.
* \tparam FromT Type of a TL-object to move from, this is auto-deduced.
* \param[in] from Wrapped pointer to a TL-object.
*/
template <class ToT, class FromT>
tl_object_ptr<ToT> move_tl_object_as(tl_object_ptr<FromT> &from) {
return tl_object_ptr<ToT>(static_cast<ToT *>(from.release()));
}
/**
* \overload
*/
template <class ToT, class FromT>
tl_object_ptr<ToT> move_tl_object_as(tl_object_ptr<FromT> &&from) {
return tl_object_ptr<ToT>(static_cast<ToT *>(from.release()));
}
} // namespace td