LLVM  6.0.0svn
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llvm::ErrorOr< T > Class Template Reference

Represents either an error or a value T. More...

#include "llvm/Support/ErrorOr.h"

Collaboration diagram for llvm::ErrorOr< T >:
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Public Types

using storage_type = typename std::conditional< isRef, wrap, T >::type
 

Public Member Functions

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=nullptr)
 
 ErrorOr (std::error_code EC)
 
template<class OtherT >
 ErrorOr (OtherT &&Val, typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *=nullptr)
 
 ErrorOr (const ErrorOr &Other)
 
template<class OtherT >
 ErrorOr (const ErrorOr< OtherT > &Other, typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *=nullptr)
 
template<class OtherT >
 ErrorOr (const ErrorOr< OtherT > &Other, typename std::enable_if< !std::is_convertible< OtherT, const T &>::value >::type *=nullptr)
 
 ErrorOr (ErrorOr &&Other)
 
template<class OtherT >
 ErrorOr (ErrorOr< OtherT > &&Other, typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *=nullptr)
 
template<class OtherT >
 ErrorOr (ErrorOr< OtherT > &&Other, typename std::enable_if<!std::is_convertible< OtherT, T >::value >::type *=nullptr)
 
ErrorOroperator= (const ErrorOr &Other)
 
ErrorOroperator= (ErrorOr &&Other)
 
 ~ErrorOr ()
 
 operator bool () const
 Return false if there is an error. More...
 
reference get ()
 
const_reference get () const
 
std::error_code getError () const
 
pointer operator-> ()
 
const_pointer operator-> () const
 
reference operator* ()
 
const_reference operator* () const
 

Friends

template<class OtherT >
class ErrorOr
 

Detailed Description

template<class T>
class llvm::ErrorOr< T >

Represents either an error or a value T.

ErrorOr<T> is a pointer-like class that represents the result of an operation. The result is either an error, or a value of type T. This is designed to emulate the usage of returning a pointer where nullptr indicates failure. However instead of just knowing that the operation failed, we also have an error_code and optional user data that describes why it failed.

It is used like the following.

ErrorOr<Buffer> getBuffer();
auto buffer = getBuffer();
if (error_code ec = buffer.getError())
return ec;
buffer->write("adena");

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 behavior is slightly different. The reference is held in a std::reference_wrapper<std::remove_reference<T>::type>, and there is special handling to make operator -> work as if T was not a reference.

T cannot be a rvalue reference.

Definition at line 69 of file ErrorOr.h.

Member Typedef Documentation

◆ storage_type

template<class T>
using llvm::ErrorOr< T >::storage_type = typename std::conditional<isRef, wrap, T>::type

Definition at line 77 of file ErrorOr.h.

Constructor & Destructor Documentation

◆ ErrorOr() [1/9]

template<class T>
template<class E >
llvm::ErrorOr< T >::ErrorOr ( E  ErrorCode,
typename std::enable_if< std::is_error_code_enum< E >::value||std::is_error_condition_enum< E >::value, void *>::type  = nullptr 
)
inline

Definition at line 87 of file ErrorOr.h.

References llvm::make_error_code().

◆ ErrorOr() [2/9]

template<class T>
llvm::ErrorOr< T >::ErrorOr ( std::error_code  EC)
inline

Definition at line 95 of file ErrorOr.h.

◆ ErrorOr() [3/9]

template<class T>
template<class OtherT >
llvm::ErrorOr< T >::ErrorOr ( OtherT &&  Val,
typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *  = nullptr 
)
inline

Definition at line 100 of file ErrorOr.h.

◆ ErrorOr() [4/9]

template<class T>
llvm::ErrorOr< T >::ErrorOr ( const ErrorOr< T > &  Other)
inline

Definition at line 107 of file ErrorOr.h.

◆ ErrorOr() [5/9]

template<class T>
template<class OtherT >
llvm::ErrorOr< T >::ErrorOr ( const ErrorOr< OtherT > &  Other,
typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *  = nullptr 
)
inline

Definition at line 112 of file ErrorOr.h.

◆ ErrorOr() [6/9]

template<class T>
template<class OtherT >
llvm::ErrorOr< T >::ErrorOr ( const ErrorOr< OtherT > &  Other,
typename std::enable_if< !std::is_convertible< OtherT, const T &>::value >::type *  = nullptr 
)
inlineexplicit

Definition at line 120 of file ErrorOr.h.

◆ ErrorOr() [7/9]

template<class T>
llvm::ErrorOr< T >::ErrorOr ( ErrorOr< T > &&  Other)
inline

Definition at line 127 of file ErrorOr.h.

References Other.

◆ ErrorOr() [8/9]

template<class T>
template<class OtherT >
llvm::ErrorOr< T >::ErrorOr ( ErrorOr< OtherT > &&  Other,
typename std::enable_if< std::is_convertible< OtherT, T >::value >::type *  = nullptr 
)
inline

Definition at line 132 of file ErrorOr.h.

References Other.

◆ ErrorOr() [9/9]

template<class T>
template<class OtherT >
llvm::ErrorOr< T >::ErrorOr ( ErrorOr< OtherT > &&  Other,
typename std::enable_if<!std::is_convertible< OtherT, T >::value >::type *  = nullptr 
)
inlineexplicit

Definition at line 142 of file ErrorOr.h.

References Other.

◆ ~ErrorOr()

template<class T>
llvm::ErrorOr< T >::~ErrorOr ( )
inline

Definition at line 159 of file ErrorOr.h.

Member Function Documentation

◆ get() [1/2]

template<class T>
reference llvm::ErrorOr< T >::get ( )
inline

◆ get() [2/2]

template<class T>
const_reference llvm::ErrorOr< T >::get ( ) const
inline

Definition at line 170 of file ErrorOr.h.

◆ getError()

template<class T>
std::error_code llvm::ErrorOr< T >::getError ( ) const
inline

◆ operator bool()

template<class T>
llvm::ErrorOr< T >::operator bool ( ) const
inlineexplicit

Return false if there is an error.

Definition at line 165 of file ErrorOr.h.

◆ operator*() [1/2]

template<class T>
reference llvm::ErrorOr< T >::operator* ( )
inline

Definition at line 182 of file ErrorOr.h.

◆ operator*() [2/2]

template<class T>
const_reference llvm::ErrorOr< T >::operator* ( ) const
inline

◆ operator->() [1/2]

template<class T>
pointer llvm::ErrorOr< T >::operator-> ( )
inline

Definition at line 176 of file ErrorOr.h.

◆ operator->() [2/2]

template<class T>
const_pointer llvm::ErrorOr< T >::operator-> ( ) const
inline

Definition at line 180 of file ErrorOr.h.

◆ operator=() [1/2]

template<class T>
ErrorOr& llvm::ErrorOr< T >::operator= ( const ErrorOr< T > &  Other)
inline

Definition at line 149 of file ErrorOr.h.

◆ operator=() [2/2]

template<class T>
ErrorOr& llvm::ErrorOr< T >::operator= ( ErrorOr< T > &&  Other)
inline

Definition at line 154 of file ErrorOr.h.

References Other.

Friends And Related Function Documentation

◆ ErrorOr

template<class T>
template<class OtherT >
friend class ErrorOr
friend

Definition at line 70 of file ErrorOr.h.

Member Data Documentation

◆ ErrorStorage

template<class T>
AlignedCharArrayUnion<std::error_code> llvm::ErrorOr< T >::ErrorStorage

Definition at line 276 of file ErrorOr.h.

◆ TStorage

template<class T>
AlignedCharArrayUnion<storage_type> llvm::ErrorOr< T >::TStorage

Definition at line 275 of file ErrorOr.h.


The documentation for this class was generated from the following file: