Nie możesz wybrać więcej, niż 25 tematów
Tematy muszą się zaczynać od litery lub cyfry, mogą zawierać myślniki ('-') i mogą mieć do 35 znaków.
90 wiersze
1.3 KiB
90 wiersze
1.3 KiB
#pragma once
|
|
|
|
#include "gp_config.hpp"
|
|
|
|
#include "gp/algorithm/modifiers.hpp"
|
|
#include "gp/algorithm/move.hpp"
|
|
#include "gp/exception.hpp"
|
|
|
|
#include <type_traits>
|
|
#include <new>
|
|
|
|
namespace gp{
|
|
struct nullopt_t{};
|
|
|
|
constexpr nullopt_t nullopt;
|
|
|
|
template<typename T>
|
|
class optional{
|
|
bool ready = false;
|
|
char buffer[sizeof(T)];
|
|
public:
|
|
constexpr optional()
|
|
: ready{false}
|
|
{}
|
|
|
|
constexpr optional(nullopt_t)
|
|
: ready{false}
|
|
{}
|
|
|
|
constexpr optional(T& value)
|
|
: ready{true}
|
|
{
|
|
new(buffer) T(value);
|
|
}
|
|
|
|
constexpr optional(T&& value)
|
|
: ready{true}
|
|
{
|
|
new(buffer) T(gp::move(value));
|
|
}
|
|
|
|
optional& operator=(nullopt_t) {
|
|
if(ready) {
|
|
((T*)buffer)->~T();
|
|
ready = false;
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
optional& operator=(T& value) {
|
|
if(ready) {
|
|
*(T*)buffer = value;
|
|
} else {
|
|
ready = true;
|
|
new(buffer) T(value);
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
optional& operator=(T&& value) {
|
|
if(ready) {
|
|
*(T*)buffer = gp::move(value);
|
|
} else {
|
|
ready = true;
|
|
new(buffer) T(gp::move(value));
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
|
|
constexpr bool has_value()
|
|
{
|
|
return ready;
|
|
}
|
|
|
|
constexpr T& value()
|
|
{
|
|
if constexpr (gp_config::has_exceptions)
|
|
{
|
|
if(!ready)
|
|
{
|
|
throw bad_optional{};
|
|
}
|
|
} else {
|
|
gp_config::assertion(ready, "bad optional access");
|
|
}
|
|
return *reinterpret_cast<T*>(buffer);
|
|
}
|
|
};
|
|
}
|