-//===- llvm/Support/ErrorOr.h - Error Smart Pointer -----------------------===//
+//===- llvm/Support/ErrorOr.h - Error Smart Pointer -------------*- C++ -*-===//
//
// The LLVM Linker
//
///
//===----------------------------------------------------------------------===//
-#ifndef LLVM_SUPPORT_ERROR_OR_H
-#define LLVM_SUPPORT_ERROR_OR_H
+#ifndef LLVM_SUPPORT_ERROROR_H
+#define LLVM_SUPPORT_ERROROR_H
+#include "llvm/ADT/PointerIntPair.h"
#include "llvm/Support/AlignOf.h"
-#include "llvm/Support/system_error.h"
-#include "llvm/Support/type_traits.h"
-
#include <cassert>
-#if LLVM_HAS_CXX11_TYPETRAITS
+#include <system_error>
#include <type_traits>
-#endif
namespace llvm {
-struct ErrorHolderBase {
- error_code Error;
- uint16_t RefCount;
- bool HasUserData;
-
- ErrorHolderBase() : RefCount(1) {}
-
- void aquire() {
- ++RefCount;
- }
-
- void release() {
- if (--RefCount == 0)
- delete this;
- }
-
-protected:
- virtual ~ErrorHolderBase() {}
-};
-
-template<class T>
-struct ErrorHolder : ErrorHolderBase {
-#if LLVM_HAS_RVALUE_REFERENCES
- ErrorHolder(T &&UD) : UserData(llvm_move(UD)) {}
-#else
- ErrorHolder(T &UD) : UserData(UD) {}
-#endif
- T UserData;
-};
-
-template<class Tp> struct ErrorOrUserDataTraits : llvm::false_type {};
-
-#if LLVM_HAS_CXX11_TYPETRAITS && LLVM_HAS_RVALUE_REFERENCES
template<class T, class V>
typename std::enable_if< std::is_constructible<T, V>::value
, typename std::remove_reference<V>::type>::type &&
moveIfMoveConstructible(V &Val) {
return Val;
}
-#else
-template<class T, class V>
-V &moveIfMoveConstructible(V &Val) {
- return Val;
-}
-#endif
/// \brief Stores a reference that can be changed.
template <typename T>
/// It is used like the following.
/// \code
/// ErrorOr<Buffer> getBuffer();
-/// void handleError(error_code ec);
///
/// auto buffer = getBuffer();
-/// if (!buffer)
-/// handleError(buffer);
+/// if (error_code ec = buffer.getError())
+/// return ec;
/// buffer->write("adena");
/// \endcode
///
-/// ErrorOr<T> also supports user defined data for specific error_codes. To use
-/// this feature you must first add a template specialization of
-/// ErrorOrUserDataTraits derived from std::true_type for your type in the lld
-/// namespace. This specialization must have a static error_code error()
-/// function that returns the error_code this data is used with.
-///
-/// getError<UserData>() may be called to get either the stored user data, or
-/// a default constructed UserData if none was stored.
///
-/// Example:
-/// \code
-/// struct InvalidArgError {
-/// InvalidArgError() {}
-/// InvalidArgError(std::string S) : ArgName(S) {}
-/// std::string ArgName;
-/// };
-///
-/// namespace llvm {
-/// template<>
-/// struct ErrorOrUserDataTraits<InvalidArgError> : std::true_type {
-/// static error_code error() {
-/// return make_error_code(errc::invalid_argument);
-/// }
-/// };
-/// } // end namespace llvm
-///
-/// using namespace llvm;
-///
-/// ErrorOr<int> foo() {
-/// return InvalidArgError("adena");
-/// }
-///
-/// int main() {
-/// auto a = foo();
-/// if (!a && error_code(a) == errc::invalid_argument)
-/// llvm::errs() << a.getError<InvalidArgError>().ArgName << "\n";
-/// }
-/// \endcode
-///
-/// An implicit conversion to bool provides a way to check if there was an
-/// error. The unary * and -> operators provide pointer like access to the
-/// value. Accessing the value when there is an error has undefined behavior.
+/// Implicit conversion to bool returns true if there is a usable value. The
+/// unary * and -> operators provide pointer like access to the value. Accessing
+/// the value when there is an error has undefined behavior.
///
/// When T is a reference type the behaivor is slightly different. The reference
/// is held in a std::reference_wrapper<std::remove_reference<T>::type>, and
/// T cannot be a rvalue reference.
template<class T>
class ErrorOr {
- static const bool isRef = is_reference<T>::value;
- typedef ReferenceStorage<typename remove_reference<T>::type> wrap;
+ template <class OtherT> friend class ErrorOr;
+ static const bool isRef = std::is_reference<T>::value;
+ typedef ReferenceStorage<typename std::remove_reference<T>::type> wrap;
public:
- typedef typename
- conditional< isRef
- , wrap
- , T
- >::type storage_type;
+ typedef typename std::conditional<isRef, wrap, T>::type storage_type;
private:
- typedef typename remove_reference<T>::type &reference;
- typedef typename remove_reference<T>::type *pointer;
+ typedef typename std::remove_reference<T>::type &reference;
+ typedef const typename std::remove_reference<T>::type &const_reference;
+ typedef typename std::remove_reference<T>::type *pointer;
+ typedef const typename std::remove_reference<T>::type *const_pointer;
public:
- ErrorOr() : IsValid(false) {}
+ template <class E>
+ ErrorOr(E ErrorCode,
+ typename std::enable_if<std::is_error_code_enum<E>::value ||
+ std::is_error_condition_enum<E>::value,
+ void *>::type = 0)
+ : HasError(true) {
+ new (getErrorStorage()) std::error_code(make_error_code(ErrorCode));
+ }
- ErrorOr(llvm::error_code EC) : HasError(true), IsValid(true) {
- Error = new ErrorHolderBase;
- Error->Error = EC;
- Error->HasUserData = false;
+ ErrorOr(std::error_code EC) : HasError(true) {
+ new (getErrorStorage()) std::error_code(EC);
}
- template<class UserDataT>
- ErrorOr(UserDataT UD, typename
- enable_if_c<ErrorOrUserDataTraits<UserDataT>::value>::type* = 0)
- : HasError(true), IsValid(true) {
- Error = new ErrorHolder<UserDataT>(llvm_move(UD));
- Error->Error = ErrorOrUserDataTraits<UserDataT>::error();
- Error->HasUserData = true;
+ ErrorOr(T Val) : HasError(false) {
+ new (getStorage()) storage_type(moveIfMoveConstructible<storage_type>(Val));
}
- ErrorOr(T Val) : HasError(false), IsValid(true) {
- new (get()) storage_type(moveIfMoveConstructible<storage_type>(Val));
+ ErrorOr(const ErrorOr &Other) {
+ copyConstruct(Other);
}
- ErrorOr(const ErrorOr &Other) : IsValid(false) {
- // Construct an invalid ErrorOr if other is invalid.
- if (!Other.IsValid)
- return;
- if (!Other.HasError) {
- // Get the other value.
- new (get()) storage_type(*Other.get());
- HasError = false;
- } else {
- // Get other's error.
- Error = Other.Error;
- HasError = true;
- Error->aquire();
- }
+ template <class OtherT>
+ ErrorOr(
+ const ErrorOr<OtherT> &Other,
+ typename std::enable_if<std::is_convertible<OtherT, T>::value>::type * =
+ nullptr) {
+ copyConstruct(Other);
+ }
- IsValid = true;
+ template <class OtherT>
+ explicit ErrorOr(
+ const ErrorOr<OtherT> &Other,
+ typename std::enable_if<
+ !std::is_convertible<OtherT, const T &>::value>::type * = nullptr) {
+ copyConstruct(Other);
}
- ErrorOr &operator =(const ErrorOr &Other) {
- if (this == &Other)
- return *this;
+ ErrorOr(ErrorOr &&Other) {
+ moveConstruct(std::move(Other));
+ }
- this->~ErrorOr();
- new (this) ErrorOr(Other);
+ template <class OtherT>
+ ErrorOr(
+ ErrorOr<OtherT> &&Other,
+ typename std::enable_if<std::is_convertible<OtherT, T>::value>::type * =
+ nullptr) {
+ moveConstruct(std::move(Other));
+ }
+
+ // This might eventually need SFINAE but it's more complex than is_convertible
+ // & I'm too lazy to write it right now.
+ template <class OtherT>
+ explicit ErrorOr(
+ ErrorOr<OtherT> &&Other,
+ typename std::enable_if<!std::is_convertible<OtherT, T>::value>::type * =
+ nullptr) {
+ moveConstruct(std::move(Other));
+ }
+ ErrorOr &operator=(const ErrorOr &Other) {
+ copyAssign(Other);
return *this;
}
-#if LLVM_HAS_RVALUE_REFERENCES
- ErrorOr(ErrorOr &&Other) : IsValid(false) {
- // Construct an invalid ErrorOr if other is invalid.
- if (!Other.IsValid)
- return;
+ ErrorOr &operator=(ErrorOr &&Other) {
+ moveAssign(std::move(Other));
+ return *this;
+ }
+
+ ~ErrorOr() {
+ if (!HasError)
+ getStorage()->~storage_type();
+ }
+
+ /// \brief Return false if there is an error.
+ explicit operator bool() const {
+ return !HasError;
+ }
+
+ reference get() { return *getStorage(); }
+ const_reference get() const { return const_cast<ErrorOr<T> *>(this)->get(); }
+
+ std::error_code getError() const {
+ return HasError ? *getErrorStorage() : std::error_code();
+ }
+
+ pointer operator ->() {
+ return toPointer(getStorage());
+ }
+
+ const_pointer operator->() const { return toPointer(getStorage()); }
+
+ reference operator *() {
+ return *getStorage();
+ }
+
+ const_reference operator*() const { return *getStorage(); }
+
+private:
+ template <class OtherT>
+ void copyConstruct(const ErrorOr<OtherT> &Other) {
if (!Other.HasError) {
// Get the other value.
- IsValid = true;
- new (get()) storage_type(std::move(*Other.get()));
HasError = false;
- // Tell other not to do any destruction.
- Other.IsValid = false;
+ new (getStorage()) storage_type(*Other.getStorage());
} else {
// Get other's error.
- Error = Other.Error;
HasError = true;
- // Tell other not to do any destruction.
- Other.IsValid = false;
+ new (getErrorStorage()) std::error_code(Other.getError());
}
-
- IsValid = true;
- }
-
- ErrorOr &operator =(ErrorOr &&Other) {
- if (this == &Other)
- return *this;
-
- this->~ErrorOr();
- new (this) ErrorOr(std::move(Other));
-
- return *this;
}
- ~ErrorOr() {
- if (!IsValid)
- return;
- if (HasError)
- Error->release();
- else
- get()->~storage_type();
+ template <class T1>
+ static bool compareThisIfSameType(const T1 &a, const T1 &b) {
+ return &a == &b;
}
-#endif
- template<class ET>
- ET getError() const {
- assert(IsValid && "Cannot get the error of a default constructed ErrorOr!");
- assert(HasError && "Cannot get an error if none exists!");
- assert(ErrorOrUserDataTraits<ET>::error() == Error->Error &&
- "Incorrect user error data type for error!");
- if (!Error->HasUserData)
- return ET();
- return reinterpret_cast<const ErrorHolder<ET>*>(Error)->UserData;
+ template <class T1, class T2>
+ static bool compareThisIfSameType(const T1 &a, const T2 &b) {
+ return false;
}
- typedef void (*unspecified_bool_type)();
- static void unspecified_bool_true() {}
+ template <class OtherT>
+ void copyAssign(const ErrorOr<OtherT> &Other) {
+ if (compareThisIfSameType(*this, Other))
+ return;
- /// \brief Return false if there is an error.
- operator unspecified_bool_type() const {
- assert(IsValid && "Can't do anything on a default constructed ErrorOr!");
- return HasError ? 0 : unspecified_bool_true;
+ this->~ErrorOr();
+ new (this) ErrorOr(Other);
}
- operator llvm::error_code() const {
- assert(IsValid && "Can't do anything on a default constructed ErrorOr!");
- return HasError ? Error->Error : llvm::error_code::success();
+ template <class OtherT>
+ void moveConstruct(ErrorOr<OtherT> &&Other) {
+ if (!Other.HasError) {
+ // Get the other value.
+ HasError = false;
+ new (getStorage()) storage_type(std::move(*Other.getStorage()));
+ } else {
+ // Get other's error.
+ HasError = true;
+ new (getErrorStorage()) std::error_code(Other.getError());
+ }
}
- pointer operator ->() {
- return toPointer(get());
- }
+ template <class OtherT>
+ void moveAssign(ErrorOr<OtherT> &&Other) {
+ if (compareThisIfSameType(*this, Other))
+ return;
- reference operator *() {
- return *get();
+ this->~ErrorOr();
+ new (this) ErrorOr(std::move(Other));
}
-private:
pointer toPointer(pointer Val) {
return Val;
}
+ const_pointer toPointer(const_pointer Val) const { return Val; }
+
pointer toPointer(wrap *Val) {
return &Val->get();
}
-protected:
- storage_type *get() {
- assert(IsValid && "Can't do anything on a default constructed ErrorOr!");
+ const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
+
+ storage_type *getStorage() {
assert(!HasError && "Cannot get value when an error exists!");
return reinterpret_cast<storage_type*>(TStorage.buffer);
}
- const storage_type *get() const {
- assert(IsValid && "Can't do anything on a default constructed ErrorOr!");
+ const storage_type *getStorage() const {
assert(!HasError && "Cannot get value when an error exists!");
return reinterpret_cast<const storage_type*>(TStorage.buffer);
}
+ std::error_code *getErrorStorage() {
+ assert(HasError && "Cannot get error when a value exists!");
+ return reinterpret_cast<std::error_code *>(ErrorStorage.buffer);
+ }
+
+ const std::error_code *getErrorStorage() const {
+ return const_cast<ErrorOr<T> *>(this)->getErrorStorage();
+ }
+
+
union {
AlignedCharArrayUnion<storage_type> TStorage;
- ErrorHolderBase *Error;
+ AlignedCharArrayUnion<std::error_code> ErrorStorage;
};
bool HasError : 1;
- bool IsValid : 1;
};
-template<class T, class E>
-typename enable_if_c<is_error_code_enum<E>::value ||
- is_error_condition_enum<E>::value, bool>::type
-operator ==(ErrorOr<T> &Err, E Code) {
- return error_code(Err) == Code;
+template <class T, class E>
+typename std::enable_if<std::is_error_code_enum<E>::value ||
+ std::is_error_condition_enum<E>::value,
+ bool>::type
+operator==(const ErrorOr<T> &Err, E Code) {
+ return Err.getError() == Code;
}
} // end namespace llvm
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