query/include/matador/object/collection_proxy.hpp

82 lines
2.1 KiB
C++

#ifndef MATADOR_COLLECTION_PROXY_HPP
#define MATADOR_COLLECTION_PROXY_HPP
#include <atomic>
#include "matador/object/object_ptr.hpp"
#include "matador/utils/identifier.hpp"
#include <vector>
namespace matador::object {
class abstract_collection_resolver {
public:
virtual ~abstract_collection_resolver() = default;
[[nodiscard]] const std::type_index& type() const { return type_; }
protected:
explicit abstract_collection_resolver(const std::type_index& ti) : type_(ti) {}
public:
const std::type_index type_;
};
template<typename Type>
class collection_resolver : public abstract_collection_resolver {
public:
collection_resolver() : abstract_collection_resolver(typeid(Type)) {}
virtual std::shared_ptr<Type> resolve(const utils::identifier& id) = 0;
};
template<typename Type>
class collection_proxy final {
public:
collection_proxy(std::weak_ptr<object_resolver<Type>> resolver, utils::identifier owner_id)
: owner_id_(std::move(owner_id)), resolver_(std::move(resolver)) {}
collection_proxy(std::weak_ptr<object_resolver<Type>> resolver, std::vector<object_ptr<Type>> items)
: items_(std::move(items)), resolver_(std::move(resolver)) {}
explicit collection_proxy(std::vector<object_ptr<Type>> items)
: items_(std::move(items)) {}
[[nodiscard]] const utils::identifier& owner_id() const {
return owner_id_;
}
const std::vector<object_ptr<Type>>& items() const {
return items_;
}
std::vector<object_ptr<Type>>& items() {
return items_;
}
private:
void resolve() const {
if (loaded_) {
return;
}
std::lock_guard lock(mutex_);
auto resolver = resolver_.lock();
if (!resolver) {
return;
// Todo: Add states (Detached, Attached, Transient) - if attached an no resolver is available throw runtime exception
// throw std::runtime_error("Detached proxy (session expired)");
}
items_ = resolver->resolve(owner_id_);
}
private:
const utils::identifier owner_id_;
std::atomic_bool loaded_{false};
std::vector<object_ptr<Type>> items_;
std::weak_ptr<object_resolver<Type>> resolver_{};
mutable std::mutex mutex_{};
};
}
#endif //MATADOR_COLLECTION_PROXY_HPP