Package org.apache.druid.math.expr

Class ExprMacroTable

java.lang.Object

org.apache.druid.math.expr.ExprMacroTable

Direct Known Subclasses:

GuiceExprMacroTable

public class ExprMacroTable
extends Object

Mechanism by which Druid expressions can define new functions for the Druid expression language. When ExprListenerImpl is creating a FunctionExpr, ExprMacroTable will first be checked to find the function by name, falling back to Parser.getFunction(String) to map to a built-in Function if none is defined in the macro table.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ExprMacroTable.BaseMacroFunctionExpr	Base class for Expr from ExprMacroTable.ExprMacro.
static class	ExprMacroTable.BaseScalarMacroFunctionExpr	Base class for Expr from ExprMacroTable.ExprMacro that accepts all-scalar arguments.
static interface	ExprMacroTable.ExprMacro
static interface	ExprMacroTable.ExprMacroFunctionExpr	stub interface to allow Parser.flatten(Expr) a way to recognize macro functions that exend this

Constructor Summary

Constructors

Constructor	Description
ExprMacroTable(List<ExprMacroTable.ExprMacro> macros)

Method Summary

Modifier and Type	Method	Description
Expr	get(String functionName, List<Expr> args)	Returns an expr corresponding to a function call if this table has an entry for functionName.
List<ExprMacroTable.ExprMacro>	getMacros()
static ExprMacroTable	granularity()	Specialized ExprMacroTable that only knows about TimestampFloorExprMacro, intended for use parsing generated expressions which translate Granularity into Expr
static ExprMacroTable	nil()

Methods inherited from class java.lang.Object

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

Constructor Details

ExprMacroTable

public ExprMacroTable(List<ExprMacroTable.ExprMacro> macros)

Method Details

nil

public static ExprMacroTable nil()

granularity

public static ExprMacroTable granularity()

Specialized ExprMacroTable that only knows about TimestampFloorExprMacro, intended for use parsing generated expressions which translate Granularity into Expr

getMacros

public List<ExprMacroTable.ExprMacro> getMacros()

get

@Nullable
public Expr get(String functionName,
 List<Expr> args)

Returns an expr corresponding to a function call if this table has an entry for functionName. Otherwise, returns null.

Parameters:

functionName - function name

args - function arguments

Returns:

expr for this function call, or null