Created
August 8, 2014 22:59
-
-
Save mmozeiko/39d84d2edf3400b8af0b to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#pragma once | |
#include <exception> | |
#include <stdexcept> | |
#include <utility> | |
template <class T> | |
class Expected | |
{ | |
public: | |
Expected(const T& rhs) | |
: ham(rhs) | |
, gotHam(true) | |
{ | |
} | |
Expected(T&& rhs) | |
: ham(std::move(rhs)) | |
, gotHam(true) | |
{ | |
} | |
Expected(const Expected& rhs) | |
: gotHam(rhs.gotHam) | |
{ | |
if (gotHam) | |
{ | |
new (&ham) T(rhs.ham); | |
} | |
else | |
{ | |
new (&spam) std::exception_ptr(rhs.spam); | |
} | |
} | |
Expected(Expected&& rhs) | |
: gotHam(rhs.gotHam) | |
{ | |
if (gotHam) | |
{ | |
new (&ham) T(std::move(rhs.ham)); | |
} | |
else | |
{ | |
new (&spam) std::exception_ptr(std::move(rhs.spam)); | |
} | |
} | |
void swap(Expected& rhs) | |
{ | |
if (gotHam) | |
{ | |
if (rhs.gotHam) | |
{ | |
using std::swap; | |
swap(ham, rhs.ham); | |
} | |
else | |
{ | |
auto t = std::move(rhs.spam); | |
new (&rhs.ham) T(std::move(ham)); | |
new (&spam) std::exception_ptr(t); | |
std::swap(gotHam, rhs.gotHam); | |
} | |
} | |
else | |
{ | |
if (rhs.gotHam) | |
{ | |
rhs.swap(*this); | |
} | |
else | |
{ | |
spam.swap(rhs.spam); | |
std::swap(gotHam, rhs.gotHam); | |
} | |
} | |
} | |
template <class E> | |
static Expected<T> fromException(const E& exception) | |
{ | |
if (typeid(exception) != typeid(E)) | |
{ | |
throw std::invalid_argument("slicing detected"); | |
} | |
return fromException(std::make_exception_ptr(exception)); | |
} | |
static Expected<T> fromException(std::exception_ptr p) | |
{ | |
Expected<T> result; | |
result.gotHam = false; | |
new (&result.spam) std::exception_ptr(std::move(p)); | |
return result; | |
} | |
static Expected<T> fromException() | |
{ | |
return fromException(std::current_exception()); | |
} | |
bool valid() const | |
{ | |
return gotHam; | |
} | |
T& get() | |
{ | |
if (!gotHam) | |
{ | |
std::rethrow_exception(spam); | |
} | |
return ham; | |
} | |
const T& get() const | |
{ | |
if (!gotHam) | |
{ | |
std::rethrow_exception(spam); | |
} | |
return ham; | |
} | |
template <class E> | |
bool hasException() const | |
{ | |
try | |
{ | |
if (!gotHam) | |
{ | |
std::rethrow_exception(spam); | |
} | |
} | |
catch (const E& object) | |
{ | |
return true; | |
} | |
catch (...) | |
{ | |
} | |
return false; | |
} | |
template <class F> | |
static Expected fromCode(F fun) | |
{ | |
try | |
{ | |
return Expected(fun()); | |
} | |
catch (...) | |
{ | |
return fromException(); | |
} | |
} | |
private: | |
union | |
{ | |
T ham; | |
std::exception_ptr spam; | |
}; | |
bool gotHam; | |
Expected() | |
{ | |
} | |
}; |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment