transmission/gtk/DynamicPropertyStore.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 "Utils.h"
#include <glibmm/object.h>
#include <glibmm/value.h>
#include <glibmm/wrap.h>
#include <array>
#include <functional>
#include <type_traits>
template<typename ObjectT, typename PropertyT>
class DynamicPropertyStore
{
public:
using ObjectType = ObjectT;
using PropertyType = PropertyT;
using PropertyIdType = guint;
static_assert(std::is_same_v<std::underlying_type_t<PropertyType>, PropertyIdType>);
struct PropertyInfo
{
template<typename MethodT>
using ValueType = std::invoke_result_t<MethodT, ObjectType>;
PropertyIdType id = 0;
GParamSpec* spec = nullptr;
std::function<void(ObjectType const&, Glib::ValueBase&)> getter;
PropertyInfo() = default;
template<typename MethodT>
PropertyInfo(PropertyType index, char const* name, char const* nick, char const* blurb, MethodT getter_method)
: id(static_cast<PropertyIdType>(index))
, spec(gtr_get_param_spec<ValueType<MethodT>>(name, nick, blurb))
, getter([getter_method](ObjectType const& object, Glib::ValueBase& value)
{ static_cast<Glib::Value<ValueType<MethodT>>&>(value).set((object.*getter_method)()); })
{
}
};
static inline auto const PropertyCount = static_cast<PropertyIdType>(PropertyType::N_PROPS);
public:
static DynamicPropertyStore& get() noexcept
{
static auto instance = DynamicPropertyStore();
return instance;
}
void install(GObjectClass* cls, std::initializer_list<PropertyInfo> properties)
{
cls->get_property = &DynamicPropertyStore::get_property_vfunc;
g_assert(properties_.size() == properties.size() + 1);
std::move(properties.begin(), properties.end(), properties_.begin() + 1);
for (auto id = PropertyIdType{ 1 }; id < PropertyCount; ++id)
{
g_assert(id == properties_[id].id);
g_object_class_install_property(cls, id, properties_[id].spec);
}
}
void get_value(ObjectType const& object, PropertyType index, Glib::ValueBase& value) const
{
get_property(index).getter(object, value);
}
void notify_changed(ObjectType& object, PropertyType index) const
{
g_object_notify_by_pspec(object.gobj(), get_property(index).spec);
}
private:
PropertyInfo const& get_property(PropertyType index) const noexcept
{
auto const id = static_cast<PropertyIdType>(index);
g_assert(id > 0);
g_assert(id < PropertyCount);
return properties_[id];
}
static void get_property_vfunc(GObject* object, PropertyIdType id, GValue* value, GParamSpec* /*param_spec*/)
{
if (id <= 0 || id >= PropertyCount)
{
return;
}
if (auto const* const typed_object = dynamic_cast<ObjectType const*>(Glib::wrap_auto(object)); typed_object != nullptr)
{
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-reinterpret-cast)
get().get_value(*typed_object, PropertyType{ id }, *reinterpret_cast<Glib::ValueBase*>(value));
}
}
private:
std::array<PropertyInfo, PropertyCount> properties_ = {};
};