transmission/libtransmission/settings.h

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// This file Copyright © Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#pragma once
#include <functional>
#include <typeindex>
#include <typeinfo>
#include <unordered_map>
#include <vector>
#include "libtransmission/quark.h"
#include "libtransmission/variant.h"
namespace libtransmission
{
class Settings
{
public:
void load(tr_variant const& src);
[[nodiscard]] tr_variant save() const;
protected:
Settings();
// convert from tr_variant to T
template<typename T>
using Load = bool (*)(tr_variant const& src, T* tgt);
// convert from T to tr_variant
template<typename T>
using Save = tr_variant (*)(T const& src);
template<typename T>
void add_type_handler(Load<T> load_handler, Save<T> save_handler)
{
auto const key = std::type_index(typeid(T*));
// wrap load_handler + save_handler with void* wrappers so that
// they can be stored in the save_ and load_ maps
load_.insert_or_assign(
key,
[load_handler](tr_variant const& src, void* tgt) { return load_handler(src, static_cast<T*>(tgt)); });
save_.insert_or_assign(key, [save_handler](void const* src) { return save_handler(*static_cast<T const*>(src)); });
}
struct Field
{
template<typename T>
Field(tr_quark key_in, T* ptr_in)
: key{ key_in }
, type{ typeid(T*) }
, ptr{ ptr_in }
{
}
tr_quark key;
std::type_info const& type;
void* ptr;
};
using Fields = std::vector<Field>;
[[nodiscard]] virtual Fields fields() = 0;
private:
std::unordered_map<std::type_index, std::function<tr_variant(void const* src)>> save_;
std::unordered_map<std::type_index, std::function<bool(tr_variant const& src, void* tgt)>> load_;
};
} // namespace libtransmission