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[ADT] Make Optional a literal type.

This allows returning Optional values from constexpr contexts.

Reviewed By: fhahn, dblaikie, rjmccall

Differential Revision: https://reviews.llvm.org/D86354
This commit is contained in:
Varun Gandhi 2020-08-21 01:45:44 -07:00
parent 2cc81d44bf
commit 99d53ed697
2 changed files with 91 additions and 57 deletions

View File

@ -43,21 +43,21 @@ class OptionalStorage {
public:
~OptionalStorage() { reset(); }
OptionalStorage() noexcept : empty(), hasVal(false) {}
constexpr OptionalStorage() noexcept : empty(), hasVal(false) {}
OptionalStorage(OptionalStorage const &other) : OptionalStorage() {
constexpr OptionalStorage(OptionalStorage const &other) : OptionalStorage() {
if (other.hasValue()) {
emplace(other.value);
}
}
OptionalStorage(OptionalStorage &&other) : OptionalStorage() {
constexpr OptionalStorage(OptionalStorage &&other) : OptionalStorage() {
if (other.hasValue()) {
emplace(std::move(other.value));
}
}
template <class... Args>
explicit OptionalStorage(in_place_t, Args &&... args)
constexpr explicit OptionalStorage(in_place_t, Args &&... args)
: value(std::forward<Args>(args)...), hasVal(true) {}
void reset() noexcept {
@ -67,13 +67,13 @@ public:
}
}
bool hasValue() const noexcept { return hasVal; }
constexpr bool hasValue() const noexcept { return hasVal; }
T &getValue() LLVM_LVALUE_FUNCTION noexcept {
assert(hasVal);
return value;
}
T const &getValue() const LLVM_LVALUE_FUNCTION noexcept {
constexpr T const &getValue() const LLVM_LVALUE_FUNCTION noexcept {
assert(hasVal);
return value;
}
@ -148,16 +148,16 @@ template <typename T> class OptionalStorage<T, true> {
public:
~OptionalStorage() = default;
OptionalStorage() noexcept : empty{} {}
constexpr OptionalStorage() noexcept : empty{} {}
OptionalStorage(OptionalStorage const &other) = default;
OptionalStorage(OptionalStorage &&other) = default;
constexpr OptionalStorage(OptionalStorage const &other) = default;
constexpr OptionalStorage(OptionalStorage &&other) = default;
OptionalStorage &operator=(OptionalStorage const &other) = default;
OptionalStorage &operator=(OptionalStorage &&other) = default;
template <class... Args>
explicit OptionalStorage(in_place_t, Args &&... args)
constexpr explicit OptionalStorage(in_place_t, Args &&... args)
: value(std::forward<Args>(args)...), hasVal(true) {}
void reset() noexcept {
@ -167,13 +167,13 @@ public:
}
}
bool hasValue() const noexcept { return hasVal; }
constexpr bool hasValue() const noexcept { return hasVal; }
T &getValue() LLVM_LVALUE_FUNCTION noexcept {
assert(hasVal);
return value;
}
T const &getValue() const LLVM_LVALUE_FUNCTION noexcept {
constexpr T const &getValue() const LLVM_LVALUE_FUNCTION noexcept {
assert(hasVal);
return value;
}
@ -221,11 +221,12 @@ public:
constexpr Optional() {}
constexpr Optional(NoneType) {}
Optional(const T &y) : Storage(optional_detail::in_place_t{}, y) {}
Optional(const Optional &O) = default;
constexpr Optional(const T &y) : Storage(optional_detail::in_place_t{}, y) {}
constexpr Optional(const Optional &O) = default;
Optional(T &&y) : Storage(optional_detail::in_place_t{}, std::move(y)) {}
Optional(Optional &&O) = default;
constexpr Optional(T &&y)
: Storage(optional_detail::in_place_t{}, std::move(y)) {}
constexpr Optional(Optional &&O) = default;
Optional &operator=(T &&y) {
Storage = std::move(y);
@ -238,7 +239,7 @@ public:
Storage.emplace(std::forward<ArgTypes>(Args)...);
}
static inline Optional create(const T *y) {
static constexpr Optional create(const T *y) {
return y ? Optional(*y) : Optional();
}
@ -250,16 +251,20 @@ public:
void reset() { Storage.reset(); }
const T *getPointer() const { return &Storage.getValue(); }
constexpr const T *getPointer() const { return &Storage.getValue(); }
T *getPointer() { return &Storage.getValue(); }
const T &getValue() const LLVM_LVALUE_FUNCTION { return Storage.getValue(); }
constexpr const T &getValue() const LLVM_LVALUE_FUNCTION {
return Storage.getValue();
}
T &getValue() LLVM_LVALUE_FUNCTION { return Storage.getValue(); }
explicit operator bool() const { return hasValue(); }
bool hasValue() const { return Storage.hasValue(); }
const T *operator->() const { return getPointer(); }
constexpr explicit operator bool() const { return hasValue(); }
constexpr bool hasValue() const { return Storage.hasValue(); }
constexpr const T *operator->() const { return getPointer(); }
T *operator->() { return getPointer(); }
const T &operator*() const LLVM_LVALUE_FUNCTION { return getValue(); }
constexpr const T &operator*() const LLVM_LVALUE_FUNCTION {
return getValue();
}
T &operator*() LLVM_LVALUE_FUNCTION { return getValue(); }
template <typename U>
@ -295,136 +300,152 @@ public:
};
template <typename T, typename U>
bool operator==(const Optional<T> &X, const Optional<U> &Y) {
constexpr bool operator==(const Optional<T> &X, const Optional<U> &Y) {
if (X && Y)
return *X == *Y;
return X.hasValue() == Y.hasValue();
}
template <typename T, typename U>
bool operator!=(const Optional<T> &X, const Optional<U> &Y) {
constexpr bool operator!=(const Optional<T> &X, const Optional<U> &Y) {
return !(X == Y);
}
template <typename T, typename U>
bool operator<(const Optional<T> &X, const Optional<U> &Y) {
constexpr bool operator<(const Optional<T> &X, const Optional<U> &Y) {
if (X && Y)
return *X < *Y;
return X.hasValue() < Y.hasValue();
}
template <typename T, typename U>
bool operator<=(const Optional<T> &X, const Optional<U> &Y) {
constexpr bool operator<=(const Optional<T> &X, const Optional<U> &Y) {
return !(Y < X);
}
template <typename T, typename U>
bool operator>(const Optional<T> &X, const Optional<U> &Y) {
constexpr bool operator>(const Optional<T> &X, const Optional<U> &Y) {
return Y < X;
}
template <typename T, typename U>
bool operator>=(const Optional<T> &X, const Optional<U> &Y) {
constexpr bool operator>=(const Optional<T> &X, const Optional<U> &Y) {
return !(X < Y);
}
template<typename T>
bool operator==(const Optional<T> &X, NoneType) {
template <typename T>
constexpr bool operator==(const Optional<T> &X, NoneType) {
return !X;
}
template<typename T>
bool operator==(NoneType, const Optional<T> &X) {
template <typename T>
constexpr bool operator==(NoneType, const Optional<T> &X) {
return X == None;
}
template<typename T>
bool operator!=(const Optional<T> &X, NoneType) {
template <typename T>
constexpr bool operator!=(const Optional<T> &X, NoneType) {
return !(X == None);
}
template<typename T>
bool operator!=(NoneType, const Optional<T> &X) {
template <typename T>
constexpr bool operator!=(NoneType, const Optional<T> &X) {
return X != None;
}
template <typename T> bool operator<(const Optional<T> &X, NoneType) {
template <typename T> constexpr bool operator<(const Optional<T> &X, NoneType) {
return false;
}
template <typename T> bool operator<(NoneType, const Optional<T> &X) {
template <typename T> constexpr bool operator<(NoneType, const Optional<T> &X) {
return X.hasValue();
}
template <typename T> bool operator<=(const Optional<T> &X, NoneType) {
template <typename T>
constexpr bool operator<=(const Optional<T> &X, NoneType) {
return !(None < X);
}
template <typename T> bool operator<=(NoneType, const Optional<T> &X) {
template <typename T>
constexpr bool operator<=(NoneType, const Optional<T> &X) {
return !(X < None);
}
template <typename T> bool operator>(const Optional<T> &X, NoneType) {
template <typename T> constexpr bool operator>(const Optional<T> &X, NoneType) {
return None < X;
}
template <typename T> bool operator>(NoneType, const Optional<T> &X) {
template <typename T> constexpr bool operator>(NoneType, const Optional<T> &X) {
return X < None;
}
template <typename T> bool operator>=(const Optional<T> &X, NoneType) {
template <typename T>
constexpr bool operator>=(const Optional<T> &X, NoneType) {
return None <= X;
}
template <typename T> bool operator>=(NoneType, const Optional<T> &X) {
template <typename T>
constexpr bool operator>=(NoneType, const Optional<T> &X) {
return X <= None;
}
template <typename T> bool operator==(const Optional<T> &X, const T &Y) {
template <typename T>
constexpr bool operator==(const Optional<T> &X, const T &Y) {
return X && *X == Y;
}
template <typename T> bool operator==(const T &X, const Optional<T> &Y) {
template <typename T>
constexpr bool operator==(const T &X, const Optional<T> &Y) {
return Y && X == *Y;
}
template <typename T> bool operator!=(const Optional<T> &X, const T &Y) {
template <typename T>
constexpr bool operator!=(const Optional<T> &X, const T &Y) {
return !(X == Y);
}
template <typename T> bool operator!=(const T &X, const Optional<T> &Y) {
template <typename T>
constexpr bool operator!=(const T &X, const Optional<T> &Y) {
return !(X == Y);
}
template <typename T> bool operator<(const Optional<T> &X, const T &Y) {
template <typename T>
constexpr bool operator<(const Optional<T> &X, const T &Y) {
return !X || *X < Y;
}
template <typename T> bool operator<(const T &X, const Optional<T> &Y) {
template <typename T>
constexpr bool operator<(const T &X, const Optional<T> &Y) {
return Y && X < *Y;
}
template <typename T> bool operator<=(const Optional<T> &X, const T &Y) {
template <typename T>
constexpr bool operator<=(const Optional<T> &X, const T &Y) {
return !(Y < X);
}
template <typename T> bool operator<=(const T &X, const Optional<T> &Y) {
template <typename T>
constexpr bool operator<=(const T &X, const Optional<T> &Y) {
return !(Y < X);
}
template <typename T> bool operator>(const Optional<T> &X, const T &Y) {
template <typename T>
constexpr bool operator>(const Optional<T> &X, const T &Y) {
return Y < X;
}
template <typename T> bool operator>(const T &X, const Optional<T> &Y) {
template <typename T>
constexpr bool operator>(const T &X, const Optional<T> &Y) {
return Y < X;
}
template <typename T> bool operator>=(const Optional<T> &X, const T &Y) {
template <typename T>
constexpr bool operator>=(const Optional<T> &X, const T &Y) {
return !(X < Y);
}
template <typename T> bool operator>=(const T &X, const Optional<T> &Y) {
template <typename T>
constexpr bool operator>=(const T &X, const Optional<T> &Y) {
return !(X < Y);
}

View File

@ -23,6 +23,19 @@ static_assert(is_trivially_copyable<Optional<int>>::value,
static_assert(is_trivially_copyable<Optional<std::array<int, 3>>>::value,
"trivially copyable");
void OptionalWorksInConstexpr() {
constexpr auto x1 = Optional<int>();
constexpr Optional<int> x2{};
static_assert(!x1.hasValue() && !x2.hasValue(),
"Default construction and hasValue() are contexpr");
constexpr auto y1 = Optional<int>(3);
constexpr Optional<int> y2{3};
static_assert(y1.getValue() == y2.getValue() && y1.getValue() == 3,
"Construction with value and getValue() are constexpr");
static_assert(Optional<int>{3} >= 2 && Optional<int>{1} < Optional<int>{2},
"Comparisons work in constexpr");
}
namespace {
struct NonDefaultConstructible {