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uvalue upcasting support: wip

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BlackMATov
2022-11-02 01:21:54 +07:00
parent 48395d3b13
commit 014315699f
3 changed files with 136 additions and 8 deletions
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8
headers/meta.hpp/meta_detail/value_utilities/utraits.hpp
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@@ -135,6 +135,11 @@ namespace meta_hpp::detail
return nullptr;
}
[[nodiscard]] inline const void* pointer_upcast(const void* ptr, const class_type& from, const class_type& to) {
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-const-cast)
return pointer_upcast(const_cast<void*>(ptr), from, to);
}
template < class_kind To, class_kind From >
[[nodiscard]] To* pointer_upcast(From* ptr) {
return static_cast<To*>(pointer_upcast(ptr, resolve_type<From>(), resolve_type<To>()));
@@ -142,7 +147,6 @@ namespace meta_hpp::detail
template < class_kind To, class_kind From >
[[nodiscard]] const To* pointer_upcast(const From* ptr) {
// NOLINTNEXTLINE(cppcoreguidelines-pro-type-const-cast)
return pointer_upcast<To>(const_cast<From*>(ptr));
return static_cast<const To*>(pointer_upcast(ptr, resolve_type<From>(), resolve_type<To>()));
}
}

44
headers/meta.hpp/meta_uvalue/uvalue.hpp
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@@ -17,6 +17,8 @@
#include "../meta_detail/value_traits/less_traits.hpp"
#include "../meta_detail/value_traits/ostream_traits.hpp"
#include "../meta_detail/value_utilities/utraits.hpp"
namespace meta_hpp
{
struct uvalue::vtable_t final {
@@ -327,53 +329,83 @@ namespace meta_hpp
template < typename T >
std::decay_t<T>& uvalue::cast() & {
using Tp = std::decay_t<T>;
if ( Tp* ptr = try_cast<Tp>() ) {
return *ptr;
}
detail::throw_exception_with("bad value cast");
}
template < typename T >
std::decay_t<T>&& uvalue::cast() && {
using Tp = std::decay_t<T>;
if ( Tp* ptr = try_cast<Tp>() ) {
return std::move(*ptr);
}
detail::throw_exception_with("bad value cast");
}
template < typename T >
const std::decay_t<T>& uvalue::cast() const & {
using Tp = std::decay_t<T>;
if ( const Tp* ptr = try_cast<const Tp>() ) {
return *ptr;
}
detail::throw_exception_with("bad value cast");
}
template < typename T >
const std::decay_t<T>&& uvalue::cast() const && {
using Tp = std::decay_t<T>;
if ( const Tp* ptr = try_cast<const Tp>() ) {
return std::move(*ptr);
}
detail::throw_exception_with("bad value cast");
}
template < typename T >
std::decay_t<T>* uvalue::try_cast() noexcept {
using Tp = std::decay_t<T>;
return get_type() == resolve_type<Tp>()
? vtable_t::storage_cast<Tp>(storage_)
: nullptr;
const any_type& from_type = get_type();
const any_type& to_type = resolve_type<Tp>();
if ( from_type == to_type ) {
return static_cast<Tp*>(data());
}
if ( from_type.is_class() && to_type.is_class() ) {
void* to_ptr = detail::pointer_upcast(data(), from_type.as_class(), to_type.as_class());
return static_cast<Tp*>(to_ptr);
}
return nullptr;
}
template < typename T >
const std::decay_t<T>* uvalue::try_cast() const noexcept {
using Tp = std::decay_t<T>;
return get_type() == resolve_type<Tp>()
? vtable_t::storage_cast<Tp>(storage_)
: nullptr;
const any_type& from_type = get_type();
const any_type& to_type = resolve_type<Tp>();
if ( from_type == to_type ) {
return static_cast<const Tp*>(data());
}
if ( from_type.is_class() && to_type.is_class() ) {
const void* to_ptr = detail::pointer_upcast(data(), from_type.as_class(), to_type.as_class());
return static_cast<const Tp*>(to_ptr);
}
return nullptr;
}
}

92
untests/meta_utilities/value3_tests.cpp Normal file
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@@ -0,0 +1,92 @@
/*******************************************************************************
* This file is part of the "https://github.com/blackmatov/meta.hpp"
* For conditions of distribution and use, see copyright notice in LICENSE.md
* Copyright (C) 2021-2022, by Matvey Cherevko (blackmatov@gmail.com)
******************************************************************************/
#include "../meta_untests.hpp"
namespace
{
struct base0 {
int i{21};
};
struct base1 : virtual base0 {
int j{42};
};
struct base2 : virtual base0 {
int k{84};
};
struct derived : base1, base2 {
int l{168};
};
}
TEST_CASE("meta/meta_utilities/value3") {
namespace meta = meta_hpp;
meta::class_<base0>();
meta::class_<base1>()
.base_<base0>();
meta::class_<base2>()
.base_<base0>();
meta::class_<derived>()
.base_<base1>()
.base_<base2>();
}
TEST_CASE("meta/meta_utilities/value3/cast") {
namespace meta = meta_hpp;
SUBCASE("derived") {
{
meta::uvalue v{derived{}};
CHECK(v.get_type() == meta::resolve_type<derived>());
CHECK(v.cast<base0>().i == 21);
CHECK(v.cast<base1>().j == 42);
CHECK(v.cast<base2>().k == 84);
CHECK(v.cast<derived>().l == 168);
}
{
const meta::uvalue v{derived{}};
CHECK(v.get_type() == meta::resolve_type<derived>());
CHECK(v.cast<base0>().i == 21);
CHECK(v.cast<base1>().j == 42);
CHECK(v.cast<base2>().k == 84);
CHECK(v.cast<derived>().l == 168);
}
}
}
TEST_CASE("meta/meta_utilities/value3/try_cast") {
namespace meta = meta_hpp;
SUBCASE("derived") {
{
meta::uvalue v{derived{}};
CHECK(v.get_type() == meta::resolve_type<derived>());
CHECK((v.try_cast<base0>() && v.try_cast<base0>()->i == 21));
CHECK((v.try_cast<base1>() && v.try_cast<base1>()->j == 42));
CHECK((v.try_cast<base2>() && v.try_cast<base2>()->k == 84));
CHECK((v.try_cast<derived>() && v.try_cast<derived>()->l == 168));
}
{
const meta::uvalue v{derived{}};
CHECK(v.get_type() == meta::resolve_type<derived>());
CHECK((v.try_cast<base0>() && v.try_cast<base0>()->i == 21));
CHECK((v.try_cast<base1>() && v.try_cast<base1>()->j == 42));
CHECK((v.try_cast<base2>() && v.try_cast<base2>()->k == 84));
CHECK((v.try_cast<derived>() && v.try_cast<derived>()->l == 168));
}
}
}