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//===- Optional.h - Simple variant for passing optional values --*- C++ -*-===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file provides Optional, a template class modeled in the spirit of // OCaml's 'opt' variant. The idea is to strongly type whether or not // a value can be optional. // //===----------------------------------------------------------------------===// #ifndef LLVM_ADT_OPTIONAL_H #define LLVM_ADT_OPTIONAL_H #include "llvm/ADT/None.h" #include "llvm/Support/Compiler.h" #include "llvm/Support/type_traits.h" #include <cassert> #include <memory> #include <new> #include <utility> namespace llvm { class raw_ostream; namespace optional_detail { struct in_place_t {}; /// Storage for any type. template <typename T, bool = is_trivially_copyable<T>::value> class OptionalStorage { union { char empty; T value; }; bool hasVal; public: ~OptionalStorage() { reset(); } OptionalStorage() noexcept : empty(), hasVal(false) {} OptionalStorage(OptionalStorage const &other) : OptionalStorage() { if (other.hasValue()) { emplace(other.value); } } OptionalStorage(OptionalStorage &&other) : OptionalStorage() { if (other.hasValue()) { emplace(std::move(other.value)); } } template <class... Args> explicit OptionalStorage(in_place_t, Args &&... args) : value(std::forward<Args>(args)...), hasVal(true) {} void reset() noexcept { if (hasVal) { value.~T(); hasVal = false; } } bool hasValue() const noexcept { return hasVal; } T &getValue() LLVM_LVALUE_FUNCTION noexcept { assert(hasVal); return value; } T const &getValue() const LLVM_LVALUE_FUNCTION noexcept { assert(hasVal); return value; } #if LLVM_HAS_RVALUE_REFERENCE_THIS T &&getValue() && noexcept { assert(hasVal); return std::move(value); } #endif template <class... Args> void emplace(Args &&... args) { reset(); ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...); hasVal = true; } OptionalStorage &operator=(T const &y) { if (hasValue()) { value = y; } else { ::new ((void *)std::addressof(value)) T(y); hasVal = true; } return *this; } OptionalStorage &operator=(T &&y) { if (hasValue()) { value = std::move(y); } else { ::new ((void *)std::addressof(value)) T(std::move(y)); hasVal = true; } return *this; } OptionalStorage &operator=(OptionalStorage const &other) { if (other.hasValue()) { if (hasValue()) { value = other.value; } else { ::new ((void *)std::addressof(value)) T(other.value); hasVal = true; } } else { reset(); } return *this; } OptionalStorage &operator=(OptionalStorage &&other) { if (other.hasValue()) { if (hasValue()) { value = std::move(other.value); } else { ::new ((void *)std::addressof(value)) T(std::move(other.value)); hasVal = true; } } else { reset(); } return *this; } }; template <typename T> class OptionalStorage<T, true> { union { char empty; T value; }; bool hasVal = false; public: ~OptionalStorage() = default; OptionalStorage() noexcept : empty{} {} OptionalStorage(OptionalStorage const &other) = default; 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) : value(std::forward<Args>(args)...), hasVal(true) {} void reset() noexcept { if (hasVal) { value.~T(); hasVal = false; } } bool hasValue() const noexcept { return hasVal; } T &getValue() LLVM_LVALUE_FUNCTION noexcept { assert(hasVal); return value; } T const &getValue() const LLVM_LVALUE_FUNCTION noexcept { assert(hasVal); return value; } #if LLVM_HAS_RVALUE_REFERENCE_THIS T &&getValue() && noexcept { assert(hasVal); return std::move(value); } #endif template <class... Args> void emplace(Args &&... args) { reset(); ::new ((void *)std::addressof(value)) T(std::forward<Args>(args)...); hasVal = true; } OptionalStorage &operator=(T const &y) { if (hasValue()) { value = y; } else { ::new ((void *)std::addressof(value)) T(y); hasVal = true; } return *this; } OptionalStorage &operator=(T &&y) { if (hasValue()) { value = std::move(y); } else { ::new ((void *)std::addressof(value)) T(std::move(y)); hasVal = true; } return *this; } }; } // namespace optional_detail template <typename T> class Optional { optional_detail::OptionalStorage<T> Storage; public: using value_type = T; constexpr Optional() {} constexpr Optional(NoneType) {} Optional(const T &y) : Storage(optional_detail::in_place_t{}, y) {} Optional(const Optional &O) = default; Optional(T &&y) : Storage(optional_detail::in_place_t{}, std::move(y)) {} Optional(Optional &&O) = default; Optional &operator=(T &&y) { Storage = std::move(y); return *this; } Optional &operator=(Optional &&O) = default; /// Create a new object by constructing it in place with the given arguments. template <typename... ArgTypes> void emplace(ArgTypes &&... Args) { Storage.emplace(std::forward<ArgTypes>(Args)...); } static inline Optional create(const T *y) { return y ? Optional(*y) : Optional(); } Optional &operator=(const T &y) { Storage = y; return *this; } Optional &operator=(const Optional &O) = default; void reset() { Storage.reset(); } const T *getPointer() const { return &Storage.getValue(); } T *getPointer() { return &Storage.getValue(); } 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(); } T *operator->() { return getPointer(); } const T &operator*() const LLVM_LVALUE_FUNCTION { return getValue(); } T &operator*() LLVM_LVALUE_FUNCTION { return getValue(); } template <typename U> constexpr T getValueOr(U &&value) const LLVM_LVALUE_FUNCTION { return hasValue() ? getValue() : std::forward<U>(value); } /// Apply a function to the value if present; otherwise return None. template <class Function> auto map(const Function &F) const -> Optional<decltype(F(getValue()))> { if (*this) return F(getValue()); return None; } #if LLVM_HAS_RVALUE_REFERENCE_THIS T &&getValue() && { return std::move(Storage.getValue()); } T &&operator*() && { return std::move(Storage.getValue()); } template <typename U> T getValueOr(U &&value) && { return hasValue() ? std::move(getValue()) : std::forward<U>(value); } /// Apply a function to the value if present; otherwise return None. template <class Function> auto map(const Function &F) && -> Optional<decltype(F(std::move(*this).getValue()))> { if (*this) return F(std::move(*this).getValue()); return None; } #endif }; template <typename T, typename U> 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) { return !(X == Y); } template <typename T, typename U> 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) { return !(Y < X); } template <typename T, typename U> 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) { return !(X < Y); } template<typename T> bool operator==(const Optional<T> &X, NoneType) { return !X; } template<typename T> bool operator==(NoneType, const Optional<T> &X) { return X == None; } template<typename T> bool operator!=(const Optional<T> &X, NoneType) { return !(X == None); } template<typename T> bool operator!=(NoneType, const Optional<T> &X) { return X != None; } template <typename T> bool operator<(const Optional<T> &X, NoneType) { return false; } template <typename T> bool operator<(NoneType, const Optional<T> &X) { return X.hasValue(); } template <typename T> bool operator<=(const Optional<T> &X, NoneType) { return !(None < X); } template <typename T> bool operator<=(NoneType, const Optional<T> &X) { return !(X < None); } template <typename T> bool operator>(const Optional<T> &X, NoneType) { return None < X; } template <typename T> bool operator>(NoneType, const Optional<T> &X) { return X < None; } template <typename T> bool operator>=(const Optional<T> &X, NoneType) { return None <= X; } template <typename T> bool operator>=(NoneType, const Optional<T> &X) { return X <= None; } template <typename T> 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) { return Y && X == *Y; } template <typename T> bool operator!=(const Optional<T> &X, const T &Y) { return !(X == Y); } template <typename T> bool operator!=(const T &X, const Optional<T> &Y) { return !(X == Y); } template <typename T> 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) { return Y && X < *Y; } template <typename T> bool operator<=(const Optional<T> &X, const T &Y) { return !(Y < X); } template <typename T> bool operator<=(const T &X, const Optional<T> &Y) { return !(Y < X); } template <typename T> bool operator>(const Optional<T> &X, const T &Y) { return Y < X; } template <typename T> bool operator>(const T &X, const Optional<T> &Y) { return Y < X; } template <typename T> bool operator>=(const Optional<T> &X, const T &Y) { return !(X < Y); } template <typename T> bool operator>=(const T &X, const Optional<T> &Y) { return !(X < Y); } raw_ostream &operator<<(raw_ostream &OS, NoneType); template <typename T, typename = decltype(std::declval<raw_ostream &>() << std::declval<const T &>())> raw_ostream &operator<<(raw_ostream &OS, const Optional<T> &O) { if (O) OS << *O; else OS << None; return OS; } } // end namespace llvm #endif // LLVM_ADT_OPTIONAL_H