Package org.apache.druid.segment.virtual

Class BaseExpressionColumnValueSelector

java.lang.Object

org.apache.druid.segment.virtual.BaseExpressionColumnValueSelector

All Implemented Interfaces:

HotLoopCallee, BaseDoubleColumnValueSelector, BaseFloatColumnValueSelector, BaseLongColumnValueSelector, BaseNullableColumnValueSelector, BaseObjectColumnValueSelector<ExprEval>, ColumnValueSelector<ExprEval>

Direct Known Subclasses:

ExpressionColumnValueSelector, RowBasedExpressionColumnValueSelector, SingleLongInputCachingExpressionColumnValueSelector, SingleStringInputCachingExpressionColumnValueSelector

public abstract class BaseExpressionColumnValueSelector
extends Object
implements ColumnValueSelector<ExprEval>

Base class for many (although not all) ColumnValueSelector<ExprEval>.

Field Summary

Fields inherited from interface org.apache.druid.segment.ColumnValueSelector

EMPTY_ARRAY

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	BaseExpressionColumnValueSelector(RowIdSupplier rowIdSupplier)

Method Summary

Modifier and Type	Method	Description
Class<ExprEval>	classOfObject()	Most-specific class of object returned by BaseObjectColumnValueSelector.getObject(), if known in advance.
protected abstract ExprEval<?>	eval()	Implementations override this.
double	getDouble()
float	getFloat()
long	getLong()
ExprEval<?>	getObject()	Returns the currently-selected object.
void	inspectRuntimeShape(RuntimeShapeInspector inspector)	Implementations of this method should call inspector.visit() with all fields of this class, which meet two conditions: 1.
boolean	isNull()	Returns true if the primitive long, double, or float value returned by this selector should be treated as null.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BaseExpressionColumnValueSelector

protected BaseExpressionColumnValueSelector(@Nullable
                                            RowIdSupplier rowIdSupplier)

Method Detail

getDouble

public double getDouble()

Specified by:

getDouble in interface BaseDoubleColumnValueSelector

getFloat

public float getFloat()

Specified by:

getFloat in interface BaseFloatColumnValueSelector

getLong

public long getLong()

Specified by:

getLong in interface BaseLongColumnValueSelector

isNull

public boolean isNull()

Description copied from interface: BaseNullableColumnValueSelector

Returns true if the primitive long, double, or float value returned by this selector should be treated as null. Users of BaseLongColumnValueSelector.getLong(), BaseDoubleColumnValueSelector.getDouble() and BaseFloatColumnValueSelector.getFloat() must check this method first, or else they may improperly use placeholder values returned by the primitive get methods. Users of BaseObjectColumnValueSelector.getObject() should not call this method. Instead, call "getObject" and check if it is null.

Specified by:

isNull in interface BaseNullableColumnValueSelector

getObject

@Nullable
public ExprEval<?> getObject()

Description copied from interface: BaseObjectColumnValueSelector

Returns the currently-selected object. The behavior of this method depends on the type of selector, which can be determined by calling ColumnSelectorFactory.getColumnCapabilities(String) on the same ColumnSelectorFactory that you got this selector from. If the capabilties are nonnull, the selector type is given by TypeSignature.getType(). String selectors, where type is ColumnType.STRING, may return any type of object from this method, especially in cases where the selector is casting objects to string at selection time. Callers are encouraged to avoid the need to deal with various objects by using ColumnSelectorFactory.makeDimensionSelector(org.apache.druid.query.dimension.DimensionSpec) instead. Numeric selectors, where TypeSignature.isNumeric(), may return any type of Number. Callers that wish to deal with more specific types should treat the original ColumnValueSelector as a BaseLongColumnValueSelector, BaseDoubleColumnValueSelector, or BaseFloatColumnValueSelector instead. Array selectors, where TypeSignature.isArray(), must return Object[]. The array may contain null elements, and the array itself may also be null. Selectors of unknown type, where ColumnSelectorFactory.getColumnCapabilities(String) returns null, may return any type of object. Callers must be prepared for a wide variety of possible input objects. This case is common during ingestion, where selectors are built on top of external data.

Specified by:

getObject in interface BaseObjectColumnValueSelector<ExprEval>

classOfObject

public Class<ExprEval> classOfObject()

Description copied from interface: BaseObjectColumnValueSelector

Most-specific class of object returned by BaseObjectColumnValueSelector.getObject(), if known in advance. This method returns Object when selectors do not know in advance what class of object they may return.

Specified by:

classOfObject in interface BaseObjectColumnValueSelector<ExprEval>

inspectRuntimeShape

public void inspectRuntimeShape(RuntimeShapeInspector inspector)

Description copied from interface: HotLoopCallee

Implementations of this method should call inspector.visit() with all fields of this class, which meet two conditions: 1. They are used in methods of this class, annotated with CalledFromHotLoop 2. They are either: a. Nullable objects b. Instances of HotLoopCallee c. Objects, which don't always have a specific class in runtime. For example, a field of type Set could be HashSet or TreeSet in runtime, depending on how this instance (the instance on which inspectRuntimeShape() is called) is configured. d. ByteBuffer or similar objects, where byte order matters e. boolean flags, affecting branch taking f. Arrays of objects, meeting any of conditions a-e.

Specified by:

inspectRuntimeShape in interface HotLoopCallee

eval

protected abstract ExprEval<?> eval()

Implementations override this.