org.bytedeco.arrow_dataset

Class KeyOptionalResult

java.lang.Object

org.bytedeco.javacpp.Pointer

org.bytedeco.arrow_dataset.KeyOptionalResult

All Implemented Interfaces:

AutoCloseable

@Name(value="arrow::Result<arrow::util::optional<arrow::dataset::KeyValuePartitioning::Key> >")
 @NoOffset
 @Properties(inherit=arrow_dataset.class)
public class KeyOptionalResult
extends Pointer

A class for representing either a usable value, or an error. A Result object either contains a value of type T or a Status object explaining why such a value is not present. The type T must be copy-constructible and/or move-constructible. The state of a Result object may be determined by calling ok() or status(). The ok() method returns true if the object contains a valid value. The status() method returns the internal Status object. A Result object that contains a valid value will return an OK Status for a call to status(). A value of type T may be extracted from a Result object through a call to ValueOrDie(). This function should only be called if a call to ok() returns true. Sample usage:

    arrow::Result<Foo> result = CalculateFoo();
    if (result.ok()) {
      Foo foo = result.ValueOrDie();
      foo.DoSomethingCool();
    } else {
      ARROW_LOG(ERROR) << result.status();
   }
  

If T is a move-only type, like std::unique_ptr<>, then the value should only be extracted after invoking std::move() on the Result object. Sample usage:

    arrow::Result<std::unique_ptr<Foo>> result = CalculateFoo();
    if (result.ok()) {
      std::unique_ptr<Foo> foo = std::move(result).ValueOrDie();
      foo->DoSomethingCool();
    } else {
      ARROW_LOG(ERROR) << result.status();
    }
  

Result is provided for the convenience of implementing functions that return some value but may fail during execution. For instance, consider a function with the following signature:

    arrow::Status CalculateFoo(int *output);
  

This function may instead be written as:

    arrow::Result<int> CalculateFoo();
  

Nested Class Summary

Nested classes/interfaces inherited from class org.bytedeco.javacpp.Pointer

Pointer.CustomDeallocator, Pointer.Deallocator, Pointer.NativeDeallocator, Pointer.ReferenceCounter

Field Summary

Fields inherited from class org.bytedeco.javacpp.Pointer

address, capacity, limit, position

Constructor Summary

Constructors

Constructor and Description
KeyOptionalResult() Constructs a Result object that contains a non-OK status.
KeyOptionalResult(KeyOptional value) Constructs a Result object that contains value.
KeyOptionalResult(KeyOptionalResult other) Copy constructor.
KeyOptionalResult(long size) Native array allocator.
KeyOptionalResult(Pointer p) Pointer cast constructor.
KeyOptionalResult(Status status) Constructs a Result object with the given non-OK Status object.

Method Summary

Modifier and Type	Method and Description
KeyOptional	access()
boolean	Equals(KeyOptionalResult other) Compare to another Result.
KeyOptionalResult	getPointer(long i)
KeyOptional	MoveValueUnsafe()
KeyOptional	multiply()
boolean	ok() Indicates whether the object contains a T value.
KeyOptionalResult	position(long position)
KeyOptionalResult	put(KeyOptionalResult other) Copy-assignment operator.
Status	status() Gets the stored status object, or an OK status if a T value is stored.
KeyOptional	ValueOrDie() Gets a mutable reference to the stored T value.
KeyOptional	ValueUnsafe() Cast the internally stored value to produce a new result or propagate the stored error.

Methods inherited from class org.bytedeco.javacpp.Pointer

address, asBuffer, asByteBuffer, availablePhysicalBytes, calloc, capacity, capacity, close, deallocate, deallocate, deallocateReferences, deallocator, deallocator, equals, fill, formatBytes, free, getDirectBufferAddress, getPointer, getPointer, getPointer, hashCode, interruptDeallocatorThread, isNull, isNull, limit, limit, malloc, maxBytes, maxPhysicalBytes, memchr, memcmp, memcpy, memmove, memset, offsetAddress, offsetof, offsetof, parseBytes, physicalBytes, physicalBytesInaccurate, position, put, realloc, referenceCount, releaseReference, retainReference, setNull, sizeof, sizeof, toString, totalBytes, totalCount, totalPhysicalBytes, withDeallocator, zero

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

KeyOptionalResult

public KeyOptionalResult(Pointer p)

Pointer cast constructor. Invokes Pointer(Pointer).

KeyOptionalResult

public KeyOptionalResult(long size)

Native array allocator. Access with Pointer.position(long).

KeyOptionalResult

public KeyOptionalResult()

Constructs a Result object that contains a non-OK status. This constructor is marked explicit to prevent attempts to return {} from a function with a return type of, for example, Result<std::vector<int>>. While return {} seems like it would return an empty vector, it will actually invoke the default constructor of Result.

KeyOptionalResult

public KeyOptionalResult(@Const @ByRef
                         Status status)

Constructs a Result object with the given non-OK Status object. All calls to ValueOrDie() on this object will abort. The given status must not be an OK status, otherwise this constructor will abort. This constructor is not declared explicit so that a function with a return type of Result<T> can return a Status object, and the status will be implicitly converted to the appropriate return type as a matter of convenience.

Parameters:

status - The non-OK Status object to initialize to.

KeyOptionalResult

public KeyOptionalResult(@ByRef(value=true)
                         KeyOptional value)

Constructs a Result object that contains value. The resulting object is considered to have an OK status. The wrapped element can be accessed with ValueOrDie(). This constructor is made implicit so that a function with a return type of Result<T> can return an object of type T, implicitly converting it to a Result<T> object.

Parameters:

value - The value to initialize to.

KeyOptionalResult

public KeyOptionalResult(@Const @ByRef
                         KeyOptionalResult other)

Copy constructor. This constructor needs to be explicitly defined because the presence of the move-assignment operator deletes the default copy constructor. In such a scenario, since the deleted copy constructor has stricter binding rules than the templated copy constructor, the templated constructor cannot act as a copy constructor, and any attempt to copy-construct a Result object results in a compilation error.

Parameters:

other - The value to copy from.

Method Detail

position

public KeyOptionalResult position(long position)

Overrides:

position in class Pointer

getPointer

public KeyOptionalResult getPointer(long i)

Overrides:

getPointer in class Pointer

put

@ByRef
 @Name(value="operator =")
 @NoException(value=true)
public KeyOptionalResult put(@Const @ByRef
                                                                                            KeyOptionalResult other)

Copy-assignment operator.

Parameters:

other - The Result object to copy.

Equals

@Cast(value="bool")
public boolean Equals(@Const @ByRef
                                           KeyOptionalResult other)

Compare to another Result.

ok

@Cast(value="const bool")
public boolean ok()

Indicates whether the object contains a T value. Generally instead of accessing this directly you will want to use ASSIGN_OR_RAISE defined below.

Returns:

True if this Result object's status is OK (i.e. a call to ok() returns true). If this function returns true, then it is safe to access the wrapped element through a call to ValueOrDie().

status

@Const
 @ByRef
public Status status()

Gets the stored status object, or an OK status if a T value is stored. /** /** @return The stored non-OK status object, or an OK status if this object /** has a value.

ValueOrDie

@ByRef
public KeyOptional ValueOrDie()

Gets a mutable reference to the stored T value. This method should only be called if this Result object's status is OK (i.e. a call to ok() returns true), otherwise this call will abort.

Returns:

The stored T value.

multiply

@ByRef
 @Name(value="operator *")
public KeyOptional multiply()

access

@Name(value="operator ->")
public KeyOptional access()

ValueUnsafe

@Const
 @ByRef
public KeyOptional ValueUnsafe()

Cast the internally stored value to produce a new result or propagate the stored error.

MoveValueUnsafe

@ByVal
public KeyOptional MoveValueUnsafe()