org.apache.druid.segment.virtual

Class ExpressionSelectors

java.lang.Object

org.apache.druid.segment.virtual.ExpressionSelectors

public class ExpressionSelectors
extends Object

Method Summary

Modifier and Type	Method and Description
static boolean	canMapOverDictionary(Expr.BindingAnalysis bindingAnalysis, ColumnCapabilities.Capable hasMultipleValues) Returns whether an expression can be applied to unique values of a particular column (like those in a dictionary) rather than being applied to each row individually.
static Object	coerceEvalToSelectorObject(ExprEval eval) Coerces ExprEval value back to selector friendly List if the evaluated expression result is an array type
static Expr.ObjectBinding	createBindings(ColumnSelectorFactory columnSelectorFactory, List<String> columns) Create Expr.ObjectBinding given a ColumnSelectorFactory and Expr.BindingAnalysis which provides the set of identifiers which need a binding (list of required columns), and context of whether or not they are used as array or scalar inputs
static Expr.ObjectBinding	createBindings(Expr.BindingAnalysis bindingAnalysis, ColumnSelectorFactory columnSelectorFactory) Create Expr.ObjectBinding given a ColumnSelectorFactory and Expr.BindingAnalysis which provides the set of identifiers which need a binding (list of required columns), and context of whether or not they are used as array or scalar inputs
static ColumnValueSelector	makeColumnValueSelector(ColumnSelectorFactory columnSelectorFactory, Expr expression) Makes a ColumnValueSelector whose getObject method returns an Object that is the value computed by an ExprEval.
static DimensionSelector	makeDimensionSelector(ColumnSelectorFactory columnSelectorFactory, Expr expression, ExtractionFn extractionFn) Makes a single or multi-value DimensionSelector wrapper around a ColumnValueSelector created by makeExprEvalSelector(ColumnSelectorFactory, Expr) as appropriate
static ColumnValueSelector<ExprEval>	makeExprEvalSelector(ColumnSelectorFactory columnSelectorFactory, Expr expression) Makes a ColumnValueSelector whose getObject method returns an ExprEval.
static ColumnValueSelector<ExprEval>	makeExprEvalSelector(ColumnSelectorFactory columnSelectorFactory, ExpressionPlan plan)

Methods inherited from class java.lang.Object

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

Method Detail

makeColumnValueSelector

public static ColumnValueSelector makeColumnValueSelector(ColumnSelectorFactory columnSelectorFactory,
                                                          Expr expression)

Makes a ColumnValueSelector whose getObject method returns an Object that is the value computed by an ExprEval.

See Also:

makeExprEvalSelector(ColumnSelectorFactory, Expr)

makeExprEvalSelector

public static ColumnValueSelector<ExprEval> makeExprEvalSelector(ColumnSelectorFactory columnSelectorFactory,
                                                                 Expr expression)

Makes a ColumnValueSelector whose getObject method returns an ExprEval.

See Also:

makeColumnValueSelector(ColumnSelectorFactory, Expr)

makeExprEvalSelector

public static ColumnValueSelector<ExprEval> makeExprEvalSelector(ColumnSelectorFactory columnSelectorFactory,
                                                                 ExpressionPlan plan)

makeDimensionSelector

public static DimensionSelector makeDimensionSelector(ColumnSelectorFactory columnSelectorFactory,
                                                      Expr expression,
                                                      @Nullable
                                                      ExtractionFn extractionFn)

Makes a single or multi-value DimensionSelector wrapper around a ColumnValueSelector created by makeExprEvalSelector(ColumnSelectorFactory, Expr) as appropriate

canMapOverDictionary

public static boolean canMapOverDictionary(Expr.BindingAnalysis bindingAnalysis,
                                           ColumnCapabilities.Capable hasMultipleValues)

Returns whether an expression can be applied to unique values of a particular column (like those in a dictionary) rather than being applied to each row individually. This function should only be called if you have already determined that an expression is over a single column, and that single column has a dictionary.

Parameters:

bindingAnalysis - result of calling Expr.analyzeInputs() on an expression

hasMultipleValues - result of calling ColumnCapabilities.hasMultipleValues()

createBindings

public static Expr.ObjectBinding createBindings(Expr.BindingAnalysis bindingAnalysis,
                                                ColumnSelectorFactory columnSelectorFactory)

Create Expr.ObjectBinding given a ColumnSelectorFactory and Expr.BindingAnalysis which provides the set of identifiers which need a binding (list of required columns), and context of whether or not they are used as array or scalar inputs

createBindings

public static Expr.ObjectBinding createBindings(ColumnSelectorFactory columnSelectorFactory,
                                                List<String> columns)

Create Expr.ObjectBinding given a ColumnSelectorFactory and Expr.BindingAnalysis which provides the set of identifiers which need a binding (list of required columns), and context of whether or not they are used as array or scalar inputs

coerceEvalToSelectorObject

@Nullable
public static Object coerceEvalToSelectorObject(ExprEval eval)

Coerces ExprEval value back to selector friendly List if the evaluated expression result is an array type