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Merge pull request #59 from georgemoralis/result 

Add Result<T, E> type
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georgemoralis 2023-10-19 22:33:53 +03:00 committed by GitHub
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1
CMakeLists.txt
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@ -19,6 +19,7 @@ include_directories(third-party/zydis/include/Zydis)
include_directories(third-party/winpthread/include) include_directories(third-party/winpthread/include)
include_directories(third-party/vulkan/include) include_directories(third-party/vulkan/include)
include_directories(third-party/xxhash/include) include_directories(third-party/xxhash/include)
include_directories(third-party/result/include)
add_subdirectory("third-party") add_subdirectory("third-party")
#=================== EXAMPLE =================== #=================== EXAMPLE ===================
include_directories(src) include_directories(src)

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Copyright {2016} {Mathieu Stefani}
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# Result
This is an adaption of [https://github.com/oktal/result](https://github.com/oktal/result). Make sure to support the original library!
## Overview
`Result<T, E>` is a template type that can be used to return and propage errors. It can be used to replace
exceptions in context where they are not allowed or too slow to be used. `Result<T, E>` is an algebraic data
type of `Ok(T)` that represents success and `Err(E)` representing an error.
Design of this class has been mainly inspired by Rust's [std::result](https://doc.rust-lang.org/std/result/)
```
struct Request {
};
struct Error {
enum class Kind {
Timeout,
Invalid,
TooLong
}
Error(Kind kind, std::string text);
Kind kind;
std::string text;
};
Result<Request, Error> parseRequest(const std::string& payload) {
if (payload.size() > 512) return Err(Error(Kind::TooLong, "Request exceeded maximum allowed size (512 bytes)"));
Request request;
return Ok(request);
}
std::string payload = receivePayload();
auto request = parseRequest(payload).expect("Failed to parse request");
```
To return a successfull `Result`, use the `Ok()` function. To return an error one, use the `Err()` function.
## Extract and unwrap
To extract the value from a `Result<T, E>` type, you can use the `expect()` function that will yield the value
of an `Ok(T)` or terminate the program with an error message passed as a parameter.
```
Result<uint32_t, uint32_t> r1 = Ok(3u);
auto val = r1.expect("Failed to retrieve the value");
assert(val == 3);
```
`unwrap()` can also be used to extract the value of a `Result`, yielding the value of an `Ok(T)` value or terminating
the program otherwise:
```
Result<uint32_t, uint32_t> r1 = Ok(3u);
auto val = r1.unwrap();
assert(val == 3);
```
Instead a terminating the program, `unwrapOr` can be used to return a default value for an `Err(E)` Result:
```
Result<uint32_t, uint32_t> r1 = Err(9u);
auto val = r1.unwrapOr(0);
assert(val == 0);
```
## Map and bind
To transform (or map) a `Result<T, E>` to a `Result<U, E>`, `Result` provides a `map` member function.
`map` will apply a function to a contained `Ok(T)` value and will return the result of the transformation,
and will leave an `Err(E)` untouched:
```
std::string stringify(int val) { return std::to_string(val); }
Result<uint32_t, uint32_t> r1 = Ok(2u);
auto r2 = r1.map(stringify); // Maps a Result<uint32_t, uint32_t> to Result<std::string, uint32_t>
assert(r2.unwrap(), "2");
```
Note that `map` should return a simple value and not a `Result<U, E>`. A function returning nothing (`void`)
applied to a `Result<T, E>` will yield a `Result<void, E>`.
To map a function to a contained `Err(E)` value, use the `mapError` function.
To *bind* a `Result<T, E>` to a `Result<U, E>`, you can use the `andThen` member function:
```
Result<uint32_t, uint32_t> square(uint32_t val) { return Ok(val * val); }
Result<uint32_t, uint32_t> r1 = Ok(3u);
auto r2 = r1.andThen(square);
assert(r2.unwrap(), 9);
```
Use `orElse` to apply a function to a contained `Err(E)` value:
```
Result<uint32_t, uint32_t> identity(uint32_t val) { return Ok(val); }
Result<uint32_t, uint32_t> r1 = Err(3u);
assert(r1.andThen(identity).orElse(square).unwrap(), 9);
```
## The TRY macro
Like Rust, a `TRY` macro is also provided that comes in handy when writing code that calls a lot of functions returning a `Result`.
the `TRY` macro will simply call its argument and short-cirtcuit the function returning an `Err(E)` if the operation returned an error `Result`:
```
Result<void, IoError> copy(int srcFd, const char* dstFile) {
auto fd = TRY(open(dstFile));
auto data = TRY(read(srcFd));
TRY(write(fd, data));
return Ok();
}
```
Note that this macro uses a special extension called *compound statement* only supported by gcc and clang

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/*
Mathieu Stefani, 03 mai 2016
This header provides a Result type that can be used to replace exceptions in code
that has to handle error.
Result<T, E> can be used to return and propagate an error to the caller. Result<T, E> is an algebraic
data type that can either Ok(T) to represent success or Err(E) to represent an error.
*/
#pragma once
#include <iostream>
#include <functional>
#include <type_traits>
namespace types {
template<typename T>
struct Ok {
Ok(const T& val) : val(val) { }
Ok(T&& val) : val(std::move(val)) { }
T val;
};
template<>
struct Ok<void> { };
template<typename E>
struct Err {
Err(const E& val) : val(val) { }
Err(E&& val) : val(std::move(val)) { }
E val;
};
}
template<typename T, typename CleanT = typename std::decay<T>::type>
types::Ok<CleanT> Ok(T&& val) {
return types::Ok<CleanT>(std::forward<T>(val));
}
inline types::Ok<void> Ok() {
return types::Ok<void>();
}
template<typename E, typename CleanE = typename std::decay<E>::type>
types::Err<CleanE> Err(E&& val) {
return types::Err<CleanE>(std::forward<E>(val));
}
namespace Rust {
template<typename T, typename E> struct Result;
}
namespace details {
template<typename ...> struct void_t { typedef void type; };
namespace impl {
template<typename Func> struct result_of;
template<typename Ret, typename Cls, typename... Args>
struct result_of<Ret (Cls::*)(Args...)> : public result_of<Ret (Args...)> { };
template<typename Ret, typename... Args>
struct result_of<Ret (Args...)> {
typedef Ret type;
};
}
template<typename Func>
struct result_of : public impl::result_of<decltype(&Func::operator())> { };
template<typename Ret, typename Cls, typename... Args>
struct result_of<Ret (Cls::*) (Args...) const> {
typedef Ret type;
};
template<typename Ret, typename... Args>
struct result_of<Ret (*)(Args...)> {
typedef Ret type;
};
template<typename R>
struct ResultOkType { typedef typename std::decay<R>::type type; };
template<typename T, typename E>
struct ResultOkType<Rust::Result<T, E>> {
typedef T type;
};
template<typename R>
struct ResultErrType { typedef R type; };
template<typename T, typename E>
struct ResultErrType<Rust::Result<T, E>> {
typedef typename std::remove_reference<E>::type type;
};
template<typename R> struct IsResult : public std::false_type { };
template<typename T, typename E>
struct IsResult<Rust::Result<T, E>> : public std::true_type { };
namespace ok {
namespace impl {
template<typename T> struct Map;
template<typename Ret, typename Cls, typename Arg>
struct Map<Ret (Cls::*)(Arg) const> : public Map<Ret (Arg)> { };
template<typename Ret, typename Cls, typename Arg>
struct Map<Ret (Cls::*)(Arg)> : public Map<Ret (Arg)> { };
// General implementation
template<typename Ret, typename Arg>
struct Map<Ret (Arg)> {
static_assert(!IsResult<Ret>::value,
"Can not map a callback returning a Result, use andThen instead");
template<typename T, typename E, typename Func>
static Rust::Result<Ret, E> map(const Rust::Result<T, E>& result, Func func) {
static_assert(
std::is_same<T, Arg>::value ||
std::is_convertible<T, Arg>::value,
"Incompatible types detected");
if (result.isOk()) {
auto res = func(result.storage().template get<T>());
return types::Ok<Ret>(std::move(res));
}
return types::Err<E>(result.storage().template get<E>());
}
};
// Specialization for callback returning void
template<typename Arg>
struct Map<void (Arg)> {
template<typename T, typename E, typename Func>
static Rust::Result<void, E> map(const Rust::Result<T, E>& result, Func func) {
if (result.isOk()) {
func(result.storage().template get<T>());
return types::Ok<void>();
}
return types::Err<E>(result.storage().template get<E>());
}
};
// Specialization for a void Result
template<typename Ret>
struct Map<Ret (void)> {
template<typename T, typename E, typename Func>
static Rust::Result<Ret, E> map(const Rust::Result<T, E>& result, Func func) {
static_assert(std::is_same<T, void>::value,
"Can not map a void callback on a non-void Result");
if (result.isOk()) {
auto ret = func();
return types::Ok<Ret>(std::move(ret));
}
return types::Err<E>(result.storage().template get<E>());
}
};
// Specialization for callback returning void on a void Result
template<>
struct Map<void (void)> {
template<typename T, typename E, typename Func>
static Rust::Result<void, E> map(const Rust::Result<T, E>& result, Func func) {
static_assert(std::is_same<T, void>::value,
"Can not map a void callback on a non-void Result");
if (result.isOk()) {
func();
return types::Ok<void>();
}
return types::Err<E>(result.storage().template get<E>());
}
};
// General specialization for a callback returning a Result
template<typename U, typename E, typename Arg>
struct Map<Rust::Result<U, E> (Arg)> {
template<typename T, typename Func>
static Rust::Result<U, E> map(const Rust::Result<T, E>& result, Func func) {
static_assert(
std::is_same<T, Arg>::value ||
std::is_convertible<T, Arg>::value,
"Incompatible types detected");
if (result.isOk()) {
auto res = func(result.storage().template get<T>());
return res;
}
return types::Err<E>(result.storage().template get<E>());
}
};
// Specialization for a void callback returning a Result
template<typename U, typename E>
struct Map<Rust::Result<U, E> (void)> {
template<typename T, typename Func>
static Rust::Result<U, E> map(const Rust::Result<T, E>& result, Func func) {
static_assert(std::is_same<T, void>::value, "Can not call a void-callback on a non-void Result");
if (result.isOk()) {
auto res = func();
return res;
}
return types::Err<E>(result.storage().template get<E>());
}
};
} // namespace impl
template<typename Func> struct Map : public impl::Map<decltype(&Func::operator())> { };
template<typename Ret, typename... Args>
struct Map<Ret (*) (Args...)> : public impl::Map<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Map<Ret (Cls::*) (Args...)> : public impl::Map<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Map<Ret (Cls::*) (Args...) const> : public impl::Map<Ret (Args...)> { };
template<typename Ret, typename... Args>
struct Map<std::function<Ret (Args...)>> : public impl::Map<Ret (Args...)> { };
} // namespace ok
namespace err {
namespace impl {
template<typename T> struct Map;
template<typename Ret, typename Cls, typename Arg>
struct Map<Ret (Cls::*)(Arg) const> {
static_assert(!IsResult<Ret>::value,
"Can not map a callback returning a Result, use orElse instead");
template<typename T, typename E, typename Func>
static Rust::Result<T, Ret> map(const Rust::Result<T, E>& result, Func func) {
if (result.isErr()) {
auto res = func(result.storage().template get<E>());
return types::Err<Ret>(res);
}
return types::Ok<T>(result.storage().template get<T>());
}
template<typename E, typename Func>
static Rust::Result<void, Ret> map(const Rust::Result<void, E>& result, Func func) {
if (result.isErr()) {
auto res = func(result.storage().template get<E>());
return types::Err<Ret>(res);
}
return types::Ok<void>();
}
};
} // namespace impl
template<typename Func> struct Map : public impl::Map<decltype(&Func::operator())> { };
} // namespace err;
namespace And {
namespace impl {
template<typename Func> struct Then;
template<typename Ret, typename... Args>
struct Then<Ret (*)(Args...)> : public Then<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Then<Ret (Cls::*)(Args...)> : public Then<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Then<Ret (Cls::*)(Args...) const> : public Then<Ret (Args...)> { };
template<typename Ret, typename Arg>
struct Then<Ret (Arg)> {
static_assert(std::is_same<Ret, void>::value,
"then() should not return anything, use map() instead");
template<typename T, typename E, typename Func>
static Rust::Result<T, E> then(const Rust::Result<T, E>& result, Func func) {
if (result.isOk()) {
func(result.storage().template get<T>());
}
return result;
}
};
template<typename Ret>
struct Then<Ret (void)> {
static_assert(std::is_same<Ret, void>::value,
"then() should not return anything, use map() instead");
template<typename T, typename E, typename Func>
static Rust::Result<T, E> then(const Rust::Result<T, E>& result, Func func) {
static_assert(std::is_same<T, void>::value, "Can not call a void-callback on a non-void Result");
if (result.isOk()) {
func();
}
return result;
}
};
} // namespace impl
template<typename Func>
struct Then : public impl::Then<decltype(&Func::operator())> { };
template<typename Ret, typename... Args>
struct Then<Ret (*) (Args...)> : public impl::Then<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Then<Ret (Cls::*)(Args...)> : public impl::Then<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Then<Ret (Cls::*)(Args...) const> : public impl::Then<Ret (Args...)> { };
} // namespace And
namespace Or {
namespace impl {
template<typename Func> struct Else;
template<typename Ret, typename... Args>
struct Else<Ret (*)(Args...)> : public Else<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Else<Ret (Cls::*)(Args...)> : public Else<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Else<Ret (Cls::*)(Args...) const> : public Else<Ret (Args...)> { };
template<typename T, typename F, typename Arg>
struct Else<Rust::Result<T, F> (Arg)> {
template<typename E, typename Func>
static Rust::Result<T, F> orElse(const Rust::Result<T, E>& result, Func func) {
static_assert(
std::is_same<E, Arg>::value ||
std::is_convertible<E, Arg>::value,
"Incompatible types detected");
if (result.isErr()) {
auto res = func(result.storage().template get<E>());
return res;
}
return types::Ok<T>(result.storage().template get<T>());
}
template<typename E, typename Func>
static Rust::Result<void, F> orElse(const Rust::Result<void, E>& result, Func func) {
if (result.isErr()) {
auto res = func(result.storage().template get<E>());
return res;
}
return types::Ok<void>();
}
};
template<typename T, typename F>
struct Else<Rust::Result<T, F> (void)> {
template<typename E, typename Func>
static Rust::Result<T, F> orElse(const Rust::Result<T, E>& result, Func func) {
static_assert(std::is_same<T, void>::value,
"Can not call a void-callback on a non-void Result");
if (result.isErr()) {
auto res = func();
return res;
}
return types::Ok<T>(result.storage().template get<T>());
}
template<typename E, typename Func>
static Rust::Result<void, F> orElse(const Rust::Result<void, E>& result, Func func) {
if (result.isErr()) {
auto res = func();
return res;
}
return types::Ok<void>();
}
};
} // namespace impl
template<typename Func>
struct Else : public impl::Else<decltype(&Func::operator())> { };
template<typename Ret, typename... Args>
struct Else<Ret (*) (Args...)> : public impl::Else<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Else<Ret (Cls::*)(Args...)> : public impl::Else<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Else<Ret (Cls::*)(Args...) const> : public impl::Else<Ret (Args...)> { };
} // namespace Or
namespace Other {
namespace impl {
template<typename Func> struct Wise;
template<typename Ret, typename... Args>
struct Wise<Ret (*)(Args...)> : public Wise<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Wise<Ret (Cls::*)(Args...)> : public Wise<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Wise<Ret (Cls::*)(Args...) const> : public Wise<Ret (Args...)> { };
template<typename Ret, typename Arg>
struct Wise<Ret (Arg)> {
template<typename T, typename E, typename Func>
static Rust::Result<T, E> otherwise(const Rust::Result<T, E>& result, Func func) {
static_assert(
std::is_same<E, Arg>::value ||
std::is_convertible<E, Arg>::value,
"Incompatible types detected");
static_assert(std::is_same<Ret, void>::value,
"callback should not return anything, use mapError() for that");
if (result.isErr()) {
func(result.storage().template get<E>());
}
return result;
}
};
} // namespace impl
template<typename Func>
struct Wise : public impl::Wise<decltype(&Func::operator())> { };
template<typename Ret, typename... Args>
struct Wise<Ret (*) (Args...)> : public impl::Wise<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Wise<Ret (Cls::*)(Args...)> : public impl::Wise<Ret (Args...)> { };
template<typename Ret, typename Cls, typename... Args>
struct Wise<Ret (Cls::*)(Args...) const> : public impl::Wise<Ret (Args...)> { };
} // namespace Other
template<typename T, typename E, typename Func,
typename Ret =
Rust::Result<
typename details::ResultOkType<
typename details::result_of<Func>::type
>::type,
E>
>
Ret map(const Rust::Result<T, E>& result, Func func) {
return ok::Map<Func>::map(result, func);
}
template<typename T, typename E, typename Func,
typename Ret =
Rust::Result<T,
typename details::ResultErrType<
typename details::result_of<Func>::type
>::type
>
>
Ret mapError(const Rust::Result<T, E>& result, Func func) {
return err::Map<Func>::map(result, func);
}
template<typename T, typename E, typename Func>
Rust::Result<T, E> then(const Rust::Result<T, E>& result, Func func) {
return And::Then<Func>::then(result, func);
}
template<typename T, typename E, typename Func>
Rust::Result<T, E> otherwise(const Rust::Result<T, E>& result, Func func) {
return Other::Wise<Func>::otherwise(result, func);
}
template<typename T, typename E, typename Func,
typename Ret =
Rust::Result<T,
typename details::ResultErrType<
typename details::result_of<Func>::type
>::type
>
>
Ret orElse(const Rust::Result<T, E>& result, Func func) {
return Or::Else<Func>::orElse(result, func);
}
struct ok_tag { };
struct err_tag { };
template<typename T, typename E>
struct Storage {
static constexpr size_t Size = sizeof(T) > sizeof(E) ? sizeof(T) : sizeof(E);
static constexpr size_t Align = sizeof(T) > sizeof(E) ? alignof(T) : alignof(E);
typedef typename std::aligned_storage<Size, Align>::type type;
Storage()
: initialized_(false)
{ }
void construct(types::Ok<T> ok)
{
new (&storage_) T(ok.val);
initialized_ = true;
}
void construct(types::Err<E> err)
{
new (&storage_) E(err.val);
initialized_ = true;
}
template<typename U>
void rawConstruct(U&& val) {
typedef typename std::decay<U>::type CleanU;
new (&storage_) CleanU(std::forward<U>(val));
initialized_ = true;
}
template<typename U>
const U& get() const {
return *reinterpret_cast<const U *>(&storage_);
}
template<typename U>
U& get() {
return *reinterpret_cast<U *>(&storage_);
}
void destroy(ok_tag) {
if (initialized_) {
get<T>().~T();
initialized_ = false;
}
}
void destroy(err_tag) {
if (initialized_) {
get<E>().~E();
initialized_ = false;
}
}
type storage_;
bool initialized_;
};
template<typename E>
struct Storage<void, E> {
typedef typename std::aligned_storage<sizeof(E), alignof(E)>::type type;
void construct(types::Ok<void>)
{
initialized_ = true;
}
void construct(types::Err<E> err)
{
new (&storage_) E(err.val);
initialized_ = true;
}
template<typename U>
void rawConstruct(U&& val) {
typedef typename std::decay<U>::type CleanU;
new (&storage_) CleanU(std::forward<U>(val));
initialized_ = true;
}
void destroy(ok_tag) { initialized_ = false; }
void destroy(err_tag) {
if (initialized_) {
get<E>().~E(); initialized_ = false;
}
}
template<typename U>
const U& get() const {
return *reinterpret_cast<const U *>(&storage_);
}
template<typename U>
U& get() {
return *reinterpret_cast<U *>(&storage_);
}
type storage_;
bool initialized_;
};
template<typename T, typename E>
struct Constructor {
static void move(Storage<T, E>&& src, Storage<T, E>& dst, ok_tag) {
dst.rawConstruct(std::move(src.template get<T>()));
src.destroy(ok_tag());
}
static void copy(const Storage<T, E>& src, Storage<T, E>& dst, ok_tag) {
dst.rawConstruct(src.template get<T>());
}
static void move(Storage<T, E>&& src, Storage<T, E>& dst, err_tag) {
dst.rawConstruct(std::move(src.template get<E>()));
src.destroy(err_tag());
}
static void copy(const Storage<T, E>& src, Storage<T, E>& dst, err_tag) {
dst.rawConstruct(src.template get<E>());
}
};
template<typename E>
struct Constructor<void, E> {
static void move(Storage<void, E>&& src, Storage<void, E>& dst, ok_tag) {
}
static void copy(const Storage<void, E>& src, Storage<void, E>& dst, ok_tag) {
}
static void move(Storage<void, E>&& src, Storage<void, E>& dst, err_tag) {
dst.rawConstruct(std::move(src.template get<E>()));
src.destroy(err_tag());
}
static void copy(const Storage<void, E>& src, Storage<void, E>& dst, err_tag) {
dst.rawConstruct(src.template get<E>());
}
};
} // namespace details
namespace rpog {
template<typename T, typename = void> struct EqualityComparable : std::false_type { };
template<typename T>
struct EqualityComparable<T,
typename std::enable_if<
true,
typename details::void_t<decltype(std::declval<T>() == std::declval<T>())>::type
>::type
> : std::true_type
{
};
} // namespace rpog
namespace Rust {
template<typename T, typename E>
struct Result {
static_assert(!std::is_same<E, void>::value, "void error type is not allowed");
typedef details::Storage<T, E> storage_type;
Result(types::Ok<T> ok)
: ok_(true)
{
storage_.construct(std::move(ok));
}
Result(types::Err<E> err)
: ok_(false)
{
storage_.construct(std::move(err));
}
Result(Result&& other) {
if (other.isOk()) {
details::Constructor<T, E>::move(std::move(other.storage_), storage_, details::ok_tag());
ok_ = true;
} else {
details::Constructor<T, E>::move(std::move(other.storage_), storage_, details::err_tag());
ok_ = false;
}
}
Result(const Result& other) {
if (other.isOk()) {
details::Constructor<T, E>::copy(other.storage_, storage_, details::ok_tag());
ok_ = true;
} else {
details::Constructor<T, E>::copy(other.storage_, storage_, details::err_tag());
ok_ = false;
}
}
~Result() {
if (ok_)
storage_.destroy(details::ok_tag());
else
storage_.destroy(details::err_tag());
}
bool isOk() const {
return ok_;
}
bool isErr() const {
return !ok_;
}
T expect(const char* str) const {
if (!isOk()) {
std::fprintf(stderr, "%s\n", str);
std::terminate();
}
return expect_impl(std::is_same<T, void>());
}
template<typename Func,
typename Ret =
Result<
typename details::ResultOkType<
typename details::result_of<Func>::type
>::type,
E>
>
Ret map(Func func) const {
return details::map(*this, func);
}
template<typename Func,
typename Ret =
Result<T,
typename details::ResultErrType<
typename details::result_of<Func>::type
>::type
>
>
Ret mapError(Func func) const {
return details::mapError(*this, func);
}
template<typename Func>
Result<T, E> then(Func func) const {
return details::then(*this, func);
}
template<typename Func>
Result<T, E> otherwise(Func func) const {
return details::otherwise(*this, func);
}
template<typename Func,
typename Ret =
Result<T,
typename details::ResultErrType<
typename details::result_of<Func>::type
>::type
>
>
Ret orElse(Func func) const {
return details::orElse(*this, func);
}
storage_type& storage() {
return storage_;
}
const storage_type& storage() const {
return storage_;
}
template<typename U = T>
typename std::enable_if<
!std::is_same<U, void>::value,
U
>::type
unwrapOr(const U& defaultValue) const {
if (isOk()) {
return storage().template get<U>();
}
return defaultValue;
}
template<typename U = T>
typename std::enable_if<
!std::is_same<U, void>::value,
U
>::type
unwrap() const {
if (isOk()) {
return storage().template get<U>();
}
std::fprintf(stderr, "Attempting to unwrap an error Result\n");
std::terminate();
}
E unwrapErr() const {
if (isErr()) {
return storage().template get<E>();
}
std::fprintf(stderr, "Attempting to unwrapErr an ok Result\n");
std::terminate();
}
private:
T expect_impl(std::true_type) const { }
T expect_impl(std::false_type) const { return storage_.template get<T>(); }
bool ok_;
storage_type storage_;
};
template<typename T, typename E>
bool operator==(const Rust::Result<T, E>& lhs, const Rust::Result<T, E>& rhs) {
static_assert(rpog::EqualityComparable<T>::value, "T must be EqualityComparable for Result to be comparable");
static_assert(rpog::EqualityComparable<E>::value, "E must be EqualityComparable for Result to be comparable");
if (lhs.isOk() && rhs.isOk()) {
return lhs.storage().template get<T>() == rhs.storage().template get<T>();
}
if (lhs.isErr() && rhs.isErr()) {
return lhs.storage().template get<E>() == rhs.storage().template get<E>();
}
}
template<typename T, typename E>
bool operator==(const Rust::Result<T, E>& lhs, types::Ok<T> ok) {
static_assert(rpog::EqualityComparable<T>::value, "T must be EqualityComparable for Result to be comparable");
if (!lhs.isOk()) return false;
return lhs.storage().template get<T>() == ok.val;
}
template<typename E>
bool operator==(const Rust::Result<void, E>& lhs, types::Ok<void>) {
return lhs.isOk();
}
template<typename T, typename E>
bool operator==(const Rust::Result<T, E>& lhs, types::Err<E> err) {
static_assert(rpog::EqualityComparable<E>::value, "E must be EqualityComparable for Result to be comparable");
if (!lhs.isErr()) return false;
return lhs.storage().template get<E>() == err.val;
}
} // end namespace Rust
#define TRY(...) \
({ \
auto res = __VA_ARGS__; \
if (!res.isOk()) { \
typedef details::ResultErrType<decltype(res)>::type E; \
return types::Err<E>(res.storage().get<E>()); \
} \
typedef details::ResultOkType<decltype(res)>::type T; \
res.storage().get<T>(); \
})