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Fix assignment chaining

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This commit is contained in:
Simon Brand
2017-11-02 08:35:04 +00:00
parent 18a2500d55
commit e4e32ea56d
1 changed files with 76 additions and 54 deletions
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94
optional.hpp
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@ -27,28 +27,33 @@
#define TL_OPTIONAL_MSVC2015 #define TL_OPTIONAL_MSVC2015
#endif #endif
#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && !defined(__clang__)) #if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && \
!defined(__clang__))
#define TL_OPTIONAL_GCC49 #define TL_OPTIONAL_GCC49
#endif #endif
#if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 4 && !defined(__clang__)) #if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 4 && \
!defined(__clang__))
#define TL_OPTIONAL_GCC54 #define TL_OPTIONAL_GCC54
#endif #endif
#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && !defined(__clang__)) #if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && \
!defined(__clang__))
// GCC < 5 doesn't support overloading on const&& for member functions // GCC < 5 doesn't support overloading on const&& for member functions
#define TL_OPTIONAL_NO_CONSTRR #define TL_OPTIONAL_NO_CONSTRR
// GCC < 5 doesn't support some standard C++11 type traits
//GCC < 5 doesn't support some standard C++11 type traits #define IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
#define IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) std::has_trivial_copy_constructor<T>::value std::has_trivial_copy_constructor<T>::value
#define IS_TRIVIALLY_COPY_ASSIGNABLE(T) std::has_trivial_copy_assign<T>::value #define IS_TRIVIALLY_COPY_ASSIGNABLE(T) std::has_trivial_copy_assign<T>::value
// This one will be different for GCC 5.7 if it's ever supported // This one will be different for GCC 5.7 if it's ever supported
#define IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>::value #define IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>::value
#else #else
#define IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) std::is_trivially_copy_constructible<T>::value #define IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
#define IS_TRIVIALLY_COPY_ASSIGNABLE(T) std::is_trivially_copy_assignable<T>::value std::is_trivially_copy_constructible<T>::value
#define IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
std::is_trivially_copy_assignable<T>::value
#define IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>::value #define IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>::value
#endif #endif
@ -280,8 +285,8 @@ struct is_nothrow_swappable
}; };
#endif #endif
// The storage base manages the actual storage, and correctly propagates trivial destruction from T // The storage base manages the actual storage, and correctly propagates trivial
// This case is for when T is trivially destructible // destruction from T This case is for when T is trivially destructible
template <class T, bool = ::std::is_trivially_destructible<T>::value> template <class T, bool = ::std::is_trivially_destructible<T>::value>
struct optional_storage_base { struct optional_storage_base {
TL_OPTIONAL_11_CONSTEXPR optional_storage_base() noexcept TL_OPTIONAL_11_CONSTEXPR optional_storage_base() noexcept
@ -327,8 +332,8 @@ template <class T> struct optional_storage_base<T, true> {
bool m_has_value = false; bool m_has_value = false;
}; };
// This base class provides some handy member functions which can be used in
// This base class provides some handy member functions which can be used in further derived classes // further derived classes
template <class T> struct optional_operations_base : optional_storage_base<T> { template <class T> struct optional_operations_base : optional_storage_base<T> {
using optional_storage_base<T>::optional_storage_base; using optional_storage_base<T>::optional_storage_base;
@ -394,16 +399,18 @@ struct optional_copy_base<T, false> : optional_operations_base<T> {
}; };
// This class manages conditionally having a trivial move constructor // This class manages conditionally having a trivial move constructor
// Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it doesn't implement an analogue to std::is_trivially_move_constructible. We have to make do with a non-trivial move constructor even if T is trivially move constructible // Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it
// doesn't implement an analogue to std::is_trivially_move_constructible. We
// have to make do with a non-trivial move constructor even if T is trivially
// move constructible
#ifndef TL_OPTIONAL_GCC49 #ifndef TL_OPTIONAL_GCC49
template <class T, bool = std::is_trivially_move_constructible<T>::value> template <class T, bool = std::is_trivially_move_constructible<T>::value>
struct optional_move_base : optional_copy_base<T> { struct optional_move_base : optional_copy_base<T> {
using optional_copy_base<T>::optional_copy_base; using optional_copy_base<T>::optional_copy_base;
}; };
#else #else
template <class T, bool = false> template <class T, bool = false> struct optional_move_base;
struct optional_move_base; #endif
#endif
template <class T> struct optional_move_base<T, false> : optional_copy_base<T> { template <class T> struct optional_move_base<T, false> : optional_copy_base<T> {
using optional_copy_base<T>::optional_copy_base; using optional_copy_base<T>::optional_copy_base;
@ -423,7 +430,9 @@ template <class T> struct optional_move_base<T, false> : optional_copy_base<T> {
}; };
// This class manages conditionally having a trivial copy assignment operator // This class manages conditionally having a trivial copy assignment operator
template <class T, bool = IS_TRIVIALLY_COPY_ASSIGNABLE(T) && IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) && IS_TRIVIALLY_DESTRUCTIBLE(T)> template <class T, bool = IS_TRIVIALLY_COPY_ASSIGNABLE(T) &&
IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) &&
IS_TRIVIALLY_DESTRUCTIBLE(T)>
struct optional_copy_assign_base : optional_move_base<T> { struct optional_copy_assign_base : optional_move_base<T> {
using optional_move_base<T>::optional_move_base; using optional_move_base<T>::optional_move_base;
}; };
@ -438,26 +447,30 @@ struct optional_copy_assign_base<T, false> : optional_move_base<T> {
optional_copy_assign_base(optional_copy_assign_base &&rhs) = default; optional_copy_assign_base(optional_copy_assign_base &&rhs) = default;
optional_copy_assign_base &operator=(const optional_copy_assign_base &rhs) { optional_copy_assign_base &operator=(const optional_copy_assign_base &rhs) {
this->assign(rhs); this->assign(rhs);
return *this;
} }
optional_copy_assign_base & optional_copy_assign_base &
operator=(optional_copy_assign_base &&rhs) = default; operator=(optional_copy_assign_base &&rhs) = default;
}; };
// This class manages conditionally having a trivial move assignment operator // This class manages conditionally having a trivial move assignment operator
// Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it doesn't implement an analogue to std::is_trivially_move_assignable. We have to make do with a non-trivial move assignment operator even if T is trivially move assignable // Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it
// doesn't implement an analogue to std::is_trivially_move_assignable. We have
// to make do with a non-trivial move assignment operator even if T is trivially
// move assignable
#ifndef TL_OPTIONAL_GCC49 #ifndef TL_OPTIONAL_GCC49
template <class T, bool = std::is_trivially_destructible<T>::value && std::is_trivially_move_constructible<T>::value && std::is_trivially_move_assignable<T>::value> template <class T, bool = std::is_trivially_destructible<T>::value
&&std::is_trivially_move_constructible<T>::value
&&std::is_trivially_move_assignable<T>::value>
struct optional_move_assign_base : optional_copy_assign_base<T> { struct optional_move_assign_base : optional_copy_assign_base<T> {
using optional_copy_assign_base<T>::optional_copy_assign_base; using optional_copy_assign_base<T>::optional_copy_assign_base;
}; };
#else #else
template <class T, bool = false> template <class T, bool = false> struct optional_move_assign_base;
struct optional_move_assign_base;
#endif #endif
template <class T> template <class T>
struct optional_move_assign_base<T, false> : optional_copy_assign_base<T> { struct optional_move_assign_base<T, false> : optional_copy_assign_base<T> {
using optional_copy_assign_base<T>::optional_copy_assign_base; using optional_copy_assign_base<T>::optional_copy_assign_base;
optional_move_assign_base() = default; optional_move_assign_base() = default;
@ -469,14 +482,14 @@ struct optional_move_assign_base : optional_copy_assign_base<T> {
std::is_nothrow_move_constructible<T>::value std::is_nothrow_move_constructible<T>::value
&&std::is_nothrow_move_assignable<T>::value) { &&std::is_nothrow_move_assignable<T>::value) {
this->assign(std::move(rhs)); this->assign(std::move(rhs));
return *this;
} }
optional_move_assign_base & optional_move_assign_base &
operator=(optional_move_assign_base &&rhs) = default; operator=(optional_move_assign_base &&rhs) = default;
}; };
// optional_delete_ctor_base will conditionally delete copy and move
// optional_delete_ctor_base will conditionally delete copy and move constructors depending on whether T is copy/move constructible // constructors depending on whether T is copy/move constructible
template <class T, bool EnableCopy = std::is_copy_constructible<T>::value, template <class T, bool EnableCopy = std::is_copy_constructible<T>::value,
bool EnableMove = std::is_move_constructible<T>::value> bool EnableMove = std::is_move_constructible<T>::value>
struct optional_delete_ctor_base { struct optional_delete_ctor_base {
@ -519,7 +532,8 @@ template <class T> struct optional_delete_ctor_base<T, false, false> {
operator=(optional_delete_ctor_base &&) noexcept = default; operator=(optional_delete_ctor_base &&) noexcept = default;
}; };
// optional_delete_assign_base will conditionally delete copy and move constructors depending on whether T is copy/move constructible + assignable // optional_delete_assign_base will conditionally delete copy and move
// constructors depending on whether T is copy/move constructible + assignable
template <class T, template <class T,
bool EnableCopy = (std::is_copy_constructible<T>::value && bool EnableCopy = (std::is_copy_constructible<T>::value &&
std::is_copy_assignable<T>::value), std::is_copy_assignable<T>::value),
@ -608,9 +622,11 @@ class optional : private detail::optional_move_assign_base<T>,
public: public:
// The different versions for C++14 and 11 are needed because deduced return // The different versions for C++14 and 11 are needed because deduced return
// types are not SFINAE-safe. This provides better support for things like generic lambdas. C.f. // types are not SFINAE-safe. This provides better support for things like
// generic lambdas. C.f.
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0826r0.html // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0826r0.html
#if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && !defined(TL_EXPECTED_GCC54) #if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && \
!defined(TL_EXPECTED_GCC54)
/// \group and_then /// \group and_then
/// Carries out some operation which returns an optional on the stored object /// Carries out some operation which returns an optional on the stored object
/// if there is one. /// if there is one.
@ -726,7 +742,8 @@ public:
#endif #endif
#endif #endif
#if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && !defined(TL_EXPECTED_GCC54) #if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && \
!defined(TL_EXPECTED_GCC54)
/// \brief Carries out some operation on the stored object if there is one. /// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f), /// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns a `std::optional<U>`. The return value is empty if /// value())`. Returns a `std::optional<U>`. The return value is empty if
@ -935,7 +952,8 @@ public:
} }
/// \group map_or_else /// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u) const &; /// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// const &;
template <class F, class U> template <class F, class U>
detail::invoke_result_t<U> map_or_else(F &&f, U &&u) const & { detail::invoke_result_t<U> map_or_else(F &&f, U &&u) const & {
return has_value() ? detail::invoke(std::forward<F>(f), **this) return has_value() ? detail::invoke(std::forward<F>(f), **this)
@ -944,7 +962,8 @@ public:
#ifndef TL_OPTIONAL_NO_CONSTRR #ifndef TL_OPTIONAL_NO_CONSTRR
/// \group map_or_else /// \group map_or_else
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u) const &&; /// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
/// const &&;
template <class F, class U> template <class F, class U>
detail::invoke_result_t<U> map_or_else(F &&f, U &&u) const && { detail::invoke_result_t<U> map_or_else(F &&f, U &&u) const && {
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this)) return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
@ -1058,7 +1077,8 @@ public:
/// Constructs the stored value in-place using the given arguments. /// Constructs the stored value in-place using the given arguments.
/// \group in_place /// \group in_place
/// \synopsis template <class... Args> constexpr explicit optional(in_place_t, Args&&... args); /// \synopsis template <class... Args> constexpr explicit optional(in_place_t,
/// Args&&... args);
template <class... Args> template <class... Args>
constexpr explicit optional( constexpr explicit optional(
detail::enable_if_t<std::is_constructible<T, Args...>::value, in_place_t>, detail::enable_if_t<std::is_constructible<T, Args...>::value, in_place_t>,
@ -1066,7 +1086,8 @@ public:
: base(in_place, std::forward<Args>(args)...) {} : base(in_place, std::forward<Args>(args)...) {}
/// \group in_place /// \group in_place
/// \synopsis template <class U, class... Args>\nconstexpr explicit optional(in_place_t, std::initializer_list<U>&, Args&&... args); /// \synopsis template <class U, class... Args>\nconstexpr explicit
/// optional(in_place_t, std::initializer_list<U>&, Args&&... args);
template <class U, class... Args> template <class U, class... Args>
TL_OPTIONAL_11_CONSTEXPR explicit optional( TL_OPTIONAL_11_CONSTEXPR explicit optional(
detail::enable_if_t<std::is_constructible<T, std::initializer_list<U> &, detail::enable_if_t<std::is_constructible<T, std::initializer_list<U> &,
@ -1223,7 +1244,8 @@ public:
} }
/// \group emplace /// \group emplace
/// \synopsis template <class U, class... Args>\nT& emplace(std::initializer_list<U> il, Args &&... args); /// \synopsis template <class U, class... Args>\nT&
/// emplace(std::initializer_list<U> il, Args &&... args);
template <class U, class... Args> template <class U, class... Args>
detail::enable_if_t< detail::enable_if_t<
std::is_constructible<T, std::initializer_list<U> &, Args &&...>::value, std::is_constructible<T, std::initializer_list<U> &, Args &&...>::value,