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hle/result: Reimplement ResultVal using Common::Expected

Common::Expected effectively provides the same functions as ResultVal, so we can implement it with this.
This can be replaced with std::expected with minimal effort should it be standardized in the C++ Standard Template Library.
This commit is contained in:
Morph 2021-11-01 10:09:37 -04:00
parent a41e9e93dd
commit 52e52924bb

View file

@ -4,11 +4,10 @@
#pragma once
#include <new>
#include <utility>
#include "common/assert.h"
#include "common/bit_field.h"
#include "common/common_types.h"
#include "common/expected.h"
// All the constants in this file come from http://switchbrew.org/index.php?title=Error_codes
@ -189,150 +188,97 @@ constexpr ResultCode ResultUnknown(UINT32_MAX);
template <typename T>
class ResultVal {
public:
/// Constructs an empty `ResultVal` with the given error code. The code must not be a success
/// code.
ResultVal(ResultCode error_code = ResultUnknown) : result_code(error_code) {
ASSERT(error_code.IsError());
}
constexpr ResultVal() : expected{} {}
/**
* Similar to the non-member function `MakeResult`, with the exception that you can manually
* specify the success code. `success_code` must not be an error code.
*/
template <typename... Args>
[[nodiscard]] static ResultVal WithCode(ResultCode success_code, Args&&... args) {
ResultVal<T> result;
result.emplace(success_code, std::forward<Args>(args)...);
return result;
}
constexpr ResultVal(ResultCode code) : expected{Common::Unexpected(code)} {}
ResultVal(const ResultVal& o) noexcept : result_code(o.result_code) {
if (!o.empty()) {
new (&object) T(o.object);
}
}
ResultVal(ResultVal&& o) noexcept : result_code(o.result_code) {
if (!o.empty()) {
new (&object) T(std::move(o.object));
}
}
~ResultVal() {
if (!empty()) {
object.~T();
}
}
ResultVal& operator=(const ResultVal& o) noexcept {
if (this == &o) {
return *this;
}
if (!empty()) {
if (!o.empty()) {
object = o.object;
} else {
object.~T();
}
} else {
if (!o.empty()) {
new (&object) T(o.object);
}
}
result_code = o.result_code;
return *this;
}
ResultVal& operator=(ResultVal&& o) noexcept {
if (this == &o) {
return *this;
}
if (!empty()) {
if (!o.empty()) {
object = std::move(o.object);
} else {
object.~T();
}
} else {
if (!o.empty()) {
new (&object) T(std::move(o.object));
}
}
result_code = o.result_code;
return *this;
}
/**
* Replaces the current result with a new constructed result value in-place. The code must not
* be an error code.
*/
template <typename... Args>
void emplace(ResultCode success_code, Args&&... args) {
ASSERT(success_code.IsSuccess());
if (!empty()) {
object.~T();
}
new (&object) T(std::forward<Args>(args)...);
result_code = success_code;
}
/// Returns true if the `ResultVal` contains an error code and no value.
[[nodiscard]] bool empty() const {
return result_code.IsError();
}
/// Returns true if the `ResultVal` contains a return value.
[[nodiscard]] bool Succeeded() const {
return result_code.IsSuccess();
}
/// Returns true if the `ResultVal` contains an error code and no value.
[[nodiscard]] bool Failed() const {
return empty();
}
[[nodiscard]] ResultCode Code() const {
return result_code;
}
[[nodiscard]] const T& operator*() const {
return object;
}
[[nodiscard]] T& operator*() {
return object;
}
[[nodiscard]] const T* operator->() const {
return &object;
}
[[nodiscard]] T* operator->() {
return &object;
}
/// Returns the value contained in this `ResultVal`, or the supplied default if it is missing.
template <typename U>
[[nodiscard]] T ValueOr(U&& value) const {
return !empty() ? object : std::move(value);
constexpr ResultVal(U&& val) : expected{std::forward<U>(val)} {}
template <typename... Args>
constexpr ResultVal(Args&&... args) : expected{std::in_place, std::forward<Args>(args)...} {}
~ResultVal() = default;
constexpr ResultVal(const ResultVal&) = default;
constexpr ResultVal(ResultVal&&) = default;
ResultVal& operator=(const ResultVal&) = default;
ResultVal& operator=(ResultVal&&) = default;
[[nodiscard]] constexpr explicit operator bool() const noexcept {
return expected.has_value();
}
/// Asserts that the result succeeded and returns a reference to it.
[[nodiscard]] T& Unwrap() & {
ASSERT_MSG(Succeeded(), "Tried to Unwrap empty ResultVal");
return **this;
[[nodiscard]] constexpr ResultCode Code() const {
return expected.has_value() ? ResultSuccess : expected.error();
}
[[nodiscard]] T&& Unwrap() && {
[[nodiscard]] constexpr bool Succeeded() const {
return expected.has_value();
}
[[nodiscard]] constexpr bool Failed() const {
return !expected.has_value();
}
[[nodiscard]] constexpr T* operator->() {
return std::addressof(expected.value());
}
[[nodiscard]] constexpr const T* operator->() const {
return std::addressof(expected.value());
}
[[nodiscard]] constexpr T& operator*() & {
return *expected;
}
[[nodiscard]] constexpr const T& operator*() const& {
return *expected;
}
[[nodiscard]] constexpr T&& operator*() && {
return *expected;
}
[[nodiscard]] constexpr const T&& operator*() const&& {
return *expected;
}
[[nodiscard]] constexpr T& Unwrap() & {
ASSERT_MSG(Succeeded(), "Tried to Unwrap empty ResultVal");
return std::move(**this);
return expected.value();
}
[[nodiscard]] constexpr const T& Unwrap() const& {
ASSERT_MSG(Succeeded(), "Tried to Unwrap empty ResultVal");
return expected.value();
}
[[nodiscard]] constexpr T&& Unwrap() && {
ASSERT_MSG(Succeeded(), "Tried to Unwrap empty ResultVal");
return std::move(expected.value());
}
[[nodiscard]] constexpr const T&& Unwrap() const&& {
ASSERT_MSG(Succeeded(), "Tried to Unwrap empty ResultVal");
return std::move(expected.value());
}
template <typename U>
[[nodiscard]] constexpr T ValueOr(U&& v) const& {
return expected.value_or(v);
}
template <typename U>
[[nodiscard]] constexpr T ValueOr(U&& v) && {
return expected.value_or(v);
}
private:
// A union is used to allocate the storage for the value, while allowing us to construct and
// destruct it at will.
union {
T object;
};
ResultCode result_code;
// TODO: Replace this with std::expected once it is standardized in the STL.
Common::Expected<T, ResultCode> expected;
};
/**
@ -341,16 +287,16 @@ private:
*/
template <typename T, typename... Args>
[[nodiscard]] ResultVal<T> MakeResult(Args&&... args) {
return ResultVal<T>::WithCode(ResultSuccess, std::forward<Args>(args)...);
return ResultVal<T>{std::forward<Args>(args)...};
}
/**
* Deducible overload of MakeResult, allowing the template parameter to be ommited if you're just
* copy or move constructing.
*/
template <typename Arg>
[[nodiscard]] ResultVal<std::remove_cvref_t<Arg>> MakeResult(Arg&& arg) {
return ResultVal<std::remove_cvref_t<Arg>>::WithCode(ResultSuccess, std::forward<Arg>(arg));
template <typename T>
[[nodiscard]] ResultVal<std::remove_cvref_t<T>> MakeResult(T&& val) {
return ResultVal<std::remove_cvref_t<T>>{std::forward<T>(val)};
}
/**