mongo_cache_type_traits.hpp

#pragma once
 
#include <chrono>
#include <type_traits>
 
#include <userver/cache/update_type.hpp>
#include <userver/utils/meta.hpp>
#include <userver/utils/void_t.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace formats::bson {
class Document;
}
 
namespace storages::mongo::operations {
class Find;
}
 
namespace mongo_cache::impl {
 
template <typename T>
using CollectionsField = decltype(T::kMongoCollectionsField);
template <typename T>
inline constexpr bool kHasCollectionsField = meta::kIsDetected<CollectionsField, T>;
 
template <typename T>
using UpdateFieldName = decltype(T::kMongoUpdateFieldName);
template <typename T>
inline constexpr bool kHasUpdateFieldName = meta::kIsDetected<UpdateFieldName, T>;
 
template <typename T>
using KeyField = decltype(T::kKeyField);
template <typename T>
inline constexpr bool kHasKeyField = meta::kIsDetected<KeyField, T>;
 
template <typename T>
using DataType = typename T::DataType;
template <typename T>
inline constexpr bool kHasValidDataType = meta::kIsMap<meta::DetectedType<DataType, T>>;
 
template <typename T>
using HasSecondaryPreferred = decltype(T::kIsSecondaryPreferred);
template <typename T>
inline constexpr bool kHasSecondaryPreferred = meta::kIsDetected<HasSecondaryPreferred, T>;
 
template <typename T>
using HasDeserializeObject = decltype(T::DeserializeObject);
template <typename T>
inline constexpr bool kHasDeserializeObject = meta::kIsDetected<HasDeserializeObject, T>;
 
template <typename T>
using HasCorrectDeserializeObject = meta::ExpectSame<
    typename T::ObjectType,
    decltype(std::declval<const T&>().DeserializeObject(std::declval<const formats::bson::Document&>()))>;
template <typename T>
inline constexpr bool kHasCorrectDeserializeObject = meta::kIsDetected<HasCorrectDeserializeObject, T>;
 
template <typename T>
using HasDefaultDeserializeObject = decltype(T::kUseDefaultDeserializeObject);
template <typename T>
inline constexpr bool kHasDefaultDeserializeObject = meta::kIsDetected<HasDefaultDeserializeObject, T>;
 
template <typename T>
using HasFindOperation = decltype(T::GetFindOperation);
template <typename T>
inline constexpr bool kHasFindOperation = meta::kIsDetected<HasFindOperation, T>;
 
template <typename T>
using HasCorrectFindOperation = meta::ExpectSame<
    storages::mongo::operations::Find,
    decltype(std::declval<const T&>().GetFindOperation(
        std::declval<cache::UpdateType>(),
        std::declval<const std::chrono::system_clock::time_point&>(),
        std::declval<const std::chrono::system_clock::time_point&>(),
        std::declval<const std::chrono::system_clock::duration&>()
    ))>;
 
template <typename T>
inline constexpr bool kHasCorrectFindOperation = meta::kIsDetected<HasCorrectFindOperation, T>;
 
template <typename T>
using HasDefaultFindOperation = decltype(T::kUseDefaultFindOperation);
template <typename T>
inline constexpr bool kHasDefaultFindOperation = meta::kIsDetected<HasDefaultFindOperation, T>;
 
template <typename T>
using HasInvalidDocumentsSkipped = decltype(T::kAreInvalidDocumentsSkipped);
template <typename T>
inline constexpr bool kHasInvalidDocumentsSkipped = meta::kIsDetected<HasInvalidDocumentsSkipped, T>;
 
template <typename>
struct ClassByMemberPointer {};
template <typename T, typename C>
struct ClassByMemberPointer<T C::*> {
    using type = C;
};
template <typename CollectionPtr>
using CollectionsType = typename ClassByMemberPointer<std::remove_cv_t<CollectionPtr>>::type;
 
template <typename MongoCacheTraits>
struct CheckTraits {
    CheckTraits() {
        if constexpr (kHasDefaultDeserializeObject<MongoCacheTraits>) {
            static_assert(
                std::is_same_v<std::decay_t<decltype(MongoCacheTraits::kUseDefaultDeserializeObject)>, bool>,
                "Mongo cache traits must specify kUseDefaultDeserializeObject as "
                "bool"
            );
        }
        if constexpr (kHasDefaultFindOperation<MongoCacheTraits>) {
            static_assert(
                std::is_same_v<std::decay_t<decltype(MongoCacheTraits::kUseDefaultFindOperation)>, bool>,
                "Mongo cache traits must specify kUseDefaultFindOperation as bool"
            );
        }
    }
 
    static_assert(kHasCollectionsField<MongoCacheTraits>, "Mongo cache traits must specify collections field");
    static_assert(kHasKeyField<MongoCacheTraits>, "Mongo cache traits must specify key field");
    static_assert(kHasValidDataType<MongoCacheTraits>, "Mongo cache traits must specify mapping data type");
 
    static_assert(kHasSecondaryPreferred<MongoCacheTraits>, "Mongo cache traits must specify read preference");
    static_assert(
        std::is_same_v<std::decay_t<decltype(MongoCacheTraits::kIsSecondaryPreferred)>, bool>,
        "Mongo cache traits must specify read preference of a bool type"
    );
 
    static_assert(kHasInvalidDocumentsSkipped<MongoCacheTraits>, "Mongo cache traits must specify validation policy");
    static_assert(
        std::is_same_v<std::decay_t<decltype(MongoCacheTraits::kAreInvalidDocumentsSkipped)>, bool>,
        "Mongo cache traits must specify validation policy of a bool type"
    );
 
    static_assert(
        kHasFindOperation<MongoCacheTraits> || kHasDefaultFindOperation<MongoCacheTraits>,
        "Mongo cache traits must specify find operation"
    );
    static_assert(
        !kHasFindOperation<MongoCacheTraits> || kHasCorrectFindOperation<MongoCacheTraits>,
        "Mongo cache traits must specify find operation with correct "
        "signature and return value type: "
        "static storages::mongo::operations::Find GetFindOperation("
        "cache::UpdateType type, "
        "const std::chrono::system_clock::time_point& last_update, "
        "const std::chrono::system_clock::time_point& now, "
        "const std::chrono::system_clock::duration& correction)"
    );
 
    static_assert(
        kHasDeserializeObject<MongoCacheTraits> || kHasDefaultDeserializeObject<MongoCacheTraits>,
        "Mongo cache traits must specify deserialize object"
    );
    static_assert(
        !kHasDeserializeObject<MongoCacheTraits> || kHasCorrectDeserializeObject<MongoCacheTraits>,
        "Mongo cache traits must specify deserialize object with correct "
        "signature and return value type: "
        "static ObjectType DeserializeObject(const formats::bson::Document& "
        "doc)"
    );
};
 
}  // namespace mongo_cache::impl
 
USERVER_NAMESPACE_END