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// Copyright 2022 The Dawn & Tint Authors
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#ifndef SRC_TINT_UTILS_REFLECTION_REFLECTION_H_
#define SRC_TINT_UTILS_REFLECTION_REFLECTION_H_
#include <cstddef>
#include <tuple>
#include <type_traits>
#include <utility>
#include "src/tint/utils/macros/foreach.h"
#include "src/tint/utils/memory/aligned_storage.h"
#include "src/tint/utils/result/result.h"
/// Forward declarations
namespace tint {
class CastableBase;
}
namespace tint::reflection::detail {
/// Helper for detecting whether the type T contains a nested Reflection class.
template <typename T, typename ENABLE = void>
struct HasReflection : std::false_type {};
/// Specialization for types that have a nested Reflection class.
template <typename T>
struct HasReflection<T, std::void_t<typename T::Reflection>> : std::true_type {};
/// Helper for inferring the base class size of T.
template <typename T, typename ENABLE = void>
struct BaseClassSize {
/// Zero as T::Base does not exist
static constexpr size_t value = 0;
};
/// Specialization for types that contain a 'Base' type alias.
template <typename T>
struct BaseClassSize<T, std::void_t<typename T::Base>> {
/// The size of T::Base, or zero if T::Base is not a base of T
static constexpr size_t value =
std::is_base_of_v<typename T::Base, T> ? sizeof(typename T::Base) : 0;
};
/// ReflectedFieldInfo describes a single reflected field. Used by CheckAllFieldsReflected()
struct ReflectedFieldInfo {
/// The field name
const std::string_view name;
/// The field size in bytes
const size_t size;
/// The field alignment in bytes
const size_t align;
/// The field offset in bytes
const size_t offset;
};
/// @returns Success if the sequential fields of @p fields have the expected offsets, and aligned
/// sum match the class size @p class_size.
::tint::Result<SuccessType> CheckAllFieldsReflected(VectorRef<ReflectedFieldInfo> fields,
std::string_view class_name,
size_t class_size,
size_t class_align,
bool class_is_castable,
std::string_view reflect_file,
uint32_t reflect_line);
/// @returns Success if the TINT_REFLECT() reflected fields of @tparam CLASS match the declaration
/// order, do not have any gaps, and fully account for the entire size of the class.
template <typename CLASS>
::tint::Result<SuccessType> CheckAllFieldsReflected() {
static_assert(!std::has_virtual_destructor_v<CLASS> || std::is_base_of_v<CastableBase, CLASS>,
"TINT_ASSERT_ALL_FIELDS_REFLECTED() cannot be used on virtual classes, except "
"for types using the tint::Castable framework");
using R = typename CLASS::Reflection;
using Fields = typename R::Fields;
Vector<ReflectedFieldInfo, std::tuple_size_v<Fields>> fields;
AlignedStorage<CLASS> obj;
R::ForeachField(obj.Get(), [&](auto&& field, std::string_view name) {
using T = std::decay_t<decltype(field)>;
size_t offset = static_cast<size_t>(reinterpret_cast<const std::byte*>(&field) -
reinterpret_cast<const std::byte*>(&obj));
fields.Push({name, sizeof(T), alignof(T), offset});
});
return CheckAllFieldsReflected(fields, R::Name, sizeof(CLASS), alignof(CLASS),
std::is_base_of_v<CastableBase, CLASS>, R::ReflectFile,
R::ReflectLine);
}
} // namespace tint::reflection::detail
namespace tint {
/// Is true if the class T has reflected its fields with TINT_REFLECT()
template <typename T>
static constexpr bool HasReflection = tint::reflection::detail::HasReflection<T>::value;
/// Calls @p callback with each field of @p object
/// @param object the object
/// @param callback a function that is called for each field of @p object.
/// @tparam CB a function with one of the signatures:
/// `void(auto& FIELD)`
/// `void(auto& FIELD, std::string_view NAME)`
template <typename OBJECT, typename CB>
void ForeachField(OBJECT& object, CB&& callback) {
using T = std::decay_t<OBJECT>;
static_assert(HasReflection<T>, "object missing TINT_REFLECT() declaration");
constexpr bool callback_field = std::is_invocable_v<std::decay_t<CB>, int&>;
constexpr bool callback_field_name =
std::is_invocable_v<std::decay_t<CB>, int&, std::string_view>;
static_assert(callback_field || callback_field_name,
"callback must have the signature of:\n"
" 'void(auto& field)'\n"
"or 'void(auto& field, std::string_view name)'");
if constexpr (callback_field) {
T::Reflection::ForeachField(object,
[&](auto& field, std::string_view) { callback(field); });
} else {
T::Reflection::ForeachField(object, std::forward<CB>(callback));
}
}
/// Calls @p callback with each field of @p object
/// @param object the object
/// @param callback a function that is called for each field of @p object.
/// @tparam CB a function with one of the signatures:
/// `void(const auto& FIELD)`
/// `void(const auto& FIELD, std::string_view NAME)`
template <typename OBJECT, typename CB>
void ForeachField(const OBJECT& object, CB&& callback) {
using T = std::decay_t<OBJECT>;
static_assert(HasReflection<T>, "object missing TINT_REFLECT() declaration");
constexpr bool callback_field = std::is_invocable_v<std::decay_t<CB>, const int&>;
constexpr bool callback_field_name =
std::is_invocable_v<std::decay_t<CB>, const int&, std::string_view>;
static_assert(callback_field || callback_field_name,
"callback must have the signature of:\n"
" 'void(auto& field)'\n"
"or 'void(auto& field, std::string_view name)'");
if constexpr (callback_field) {
T::Reflection::ForeachField(object,
[&](const auto& field, std::string_view) { callback(field); });
} else {
T::Reflection::ForeachField(object, std::forward<CB>(callback));
}
}
/// Macro used by TINT_FOREACH() in TINT_REFLECT() to generate the T::Reflection::Fields tuple.
#define TINT_REFLECT_FIELD_TYPE(FIELD) decltype(Class::FIELD),
/// Macro used by TINT_FOREACH() in TINT_REFLECT() to call the callback function with each field in
/// the variadic.
#define TINT_REFLECT_CALLBACK_FIELD(FIELD) callback(object.FIELD, #FIELD);
// TINT_REFLECT(CLASS, ...) reflects each of the fields arguments of CLASS so that the types can be
// used with tint::ForeachField().
#define TINT_REFLECT(CLASS, ...) \
struct Reflection { \
using Class = CLASS; \
using Fields = std::tuple<TINT_FOREACH(TINT_REFLECT_FIELD_TYPE, __VA_ARGS__) void>; \
[[maybe_unused]] static constexpr std::string_view Name = #CLASS; \
[[maybe_unused]] static constexpr std::string_view ReflectFile = __FILE__; \
[[maybe_unused]] static constexpr uint32_t ReflectLine = __LINE__; \
template <typename OBJECT, typename CB> \
[[maybe_unused]] static constexpr void ForeachField(OBJECT&& object, CB&& callback) { \
TINT_FOREACH(TINT_REFLECT_CALLBACK_FIELD, __VA_ARGS__) \
} \
}
/// TINT_ASSERT_ALL_FIELDS_REFLECTED(...) performs a compile-time assertion that all the fields of
/// CLASS have been reflected with TINT_REFLECT().
/// @note The order in which the fields are passed to TINT_REFLECT must match the declaration order
/// in the class.
#define TINT_ASSERT_ALL_FIELDS_REFLECTED(CLASS) \
ASSERT_EQ(::tint::reflection::detail::CheckAllFieldsReflected<CLASS>(), ::tint::Success)
/// A template that can be specialized to reflect the valid range of an enum
/// Use TINT_REFLECT_ENUM_RANGE to specialize this class
template <typename T>
struct EnumRange;
/// Declares a specialization of EnumRange for the enum ENUM with the lowest enum value MIN and
/// largest enum value MAX. Must only be used in the `tint` namespace.
#define TINT_REFLECT_ENUM_RANGE(ENUM, MIN, MAX) \
template <> \
struct EnumRange<ENUM> { \
static constexpr ENUM kMin = ENUM::MIN; \
static constexpr ENUM kMax = ENUM::MAX; \
}
} // namespace tint
#endif // SRC_TINT_UTILS_REFLECTION_REFLECTION_H_