org.apache.flink.table.functions

Class UserDefinedFunctionHelper

java.lang.Object

org.apache.flink.table.functions.UserDefinedFunctionHelper

@Internal
public final class UserDefinedFunctionHelper
extends Object

Utility for dealing with subclasses of UserDefinedFunction. The purpose of this class is to keep the user-facing APIs clean and offer methods/constants from here.

It contains methods for instantiating, validating and extracting types during function registration in a catalog.

Field Summary

Fields

Modifier and Type	Field and Description
static String	AGGREGATE_ACCUMULATE
static String	AGGREGATE_MERGE
static String	AGGREGATE_RESET
static String	AGGREGATE_RETRACT
static String	ASYNC_TABLE_EVAL
static String	SCALAR_EVAL
static String	TABLE_AGGREGATE_ACCUMULATE
static String	TABLE_AGGREGATE_EMIT
static String	TABLE_AGGREGATE_EMIT_RETRACT
static String	TABLE_AGGREGATE_RETRACT
static String	TABLE_EVAL

Method Summary

Modifier and Type	Method and Description
static <T,ACC> TypeInformation<ACC>	getAccumulatorTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction) Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
static <T,ACC> TypeInformation<ACC>	getAccumulatorTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction, TypeInformation<ACC> scalaType) Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
static <T,ACC> TypeInformation<T>	getReturnTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction) Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
static <T,ACC> TypeInformation<T>	getReturnTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction, TypeInformation<T> scalaType) Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
static <T> TypeInformation<T>	getReturnTypeOfTableFunction(TableFunction<T> tableFunction) Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
static <T> TypeInformation<T>	getReturnTypeOfTableFunction(TableFunction<T> tableFunction, TypeInformation<T> scalaType) Tries to infer the TypeInformation of an AggregateFunction's accumulator type.
static UserDefinedFunction	instantiateFunction(Class<? extends UserDefinedFunction> functionClass) Instantiates a UserDefinedFunction assuming a default constructor.
static void	prepareInstance(ReadableConfig config, UserDefinedFunction function) Prepares a UserDefinedFunction instance for usage in the API.
static void	validateClass(Class<? extends UserDefinedFunction> functionClass) Validates a UserDefinedFunction class for usage in the API.

Methods inherited from class java.lang.Object

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

Field Detail

SCALAR_EVAL

public static final String SCALAR_EVAL

See Also:

Constant Field Values

TABLE_EVAL

public static final String TABLE_EVAL

See Also:

Constant Field Values

AGGREGATE_ACCUMULATE

public static final String AGGREGATE_ACCUMULATE

See Also:

Constant Field Values

AGGREGATE_RETRACT

public static final String AGGREGATE_RETRACT

See Also:

Constant Field Values

AGGREGATE_MERGE

public static final String AGGREGATE_MERGE

See Also:

Constant Field Values

AGGREGATE_RESET

public static final String AGGREGATE_RESET

See Also:

Constant Field Values

TABLE_AGGREGATE_ACCUMULATE

public static final String TABLE_AGGREGATE_ACCUMULATE

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Constant Field Values

TABLE_AGGREGATE_RETRACT

public static final String TABLE_AGGREGATE_RETRACT

See Also:

Constant Field Values

TABLE_AGGREGATE_EMIT

public static final String TABLE_AGGREGATE_EMIT

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Constant Field Values

TABLE_AGGREGATE_EMIT_RETRACT

public static final String TABLE_AGGREGATE_EMIT_RETRACT

See Also:

Constant Field Values

ASYNC_TABLE_EVAL

public static final String ASYNC_TABLE_EVAL

See Also:

Constant Field Values

Method Detail

getReturnTypeOfAggregateFunction

public static <T,ACC> TypeInformation<T> getReturnTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction)

Tries to infer the TypeInformation of an AggregateFunction's accumulator type.

Parameters:

aggregateFunction - The AggregateFunction for which the accumulator type is inferred.

Returns:

The inferred accumulator type of the AggregateFunction.

getReturnTypeOfAggregateFunction

public static <T,ACC> TypeInformation<T> getReturnTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction,
                                                                          TypeInformation<T> scalaType)

Tries to infer the TypeInformation of an AggregateFunction's accumulator type.

Parameters:

aggregateFunction - The AggregateFunction for which the accumulator type is inferred.

scalaType - The implicitly inferred type of the accumulator type.

Returns:

The inferred accumulator type of the AggregateFunction.

getAccumulatorTypeOfAggregateFunction

public static <T,ACC> TypeInformation<ACC> getAccumulatorTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction)

Tries to infer the TypeInformation of an AggregateFunction's accumulator type.

Parameters:

aggregateFunction - The AggregateFunction for which the accumulator type is inferred.

Returns:

The inferred accumulator type of the AggregateFunction.

getAccumulatorTypeOfAggregateFunction

public static <T,ACC> TypeInformation<ACC> getAccumulatorTypeOfAggregateFunction(UserDefinedAggregateFunction<T,ACC> aggregateFunction,
                                                                                 TypeInformation<ACC> scalaType)

Tries to infer the TypeInformation of an AggregateFunction's accumulator type.

Parameters:

aggregateFunction - The AggregateFunction for which the accumulator type is inferred.

scalaType - The implicitly inferred type of the accumulator type.

Returns:

The inferred accumulator type of the AggregateFunction.

getReturnTypeOfTableFunction

public static <T> TypeInformation<T> getReturnTypeOfTableFunction(TableFunction<T> tableFunction)

Tries to infer the TypeInformation of an AggregateFunction's accumulator type.

Parameters:

tableFunction - The TableFunction for which the accumulator type is inferred.

Returns:

The inferred accumulator type of the AggregateFunction.

getReturnTypeOfTableFunction

public static <T> TypeInformation<T> getReturnTypeOfTableFunction(TableFunction<T> tableFunction,
                                                                  TypeInformation<T> scalaType)

Tries to infer the TypeInformation of an AggregateFunction's accumulator type.

Parameters:

tableFunction - The TableFunction for which the accumulator type is inferred.

scalaType - The implicitly inferred type of the accumulator type.

Returns:

The inferred accumulator type of the AggregateFunction.

instantiateFunction

public static UserDefinedFunction instantiateFunction(Class<? extends UserDefinedFunction> functionClass)

Instantiates a UserDefinedFunction assuming a default constructor.

prepareInstance

public static void prepareInstance(ReadableConfig config,
                                   UserDefinedFunction function)

Prepares a UserDefinedFunction instance for usage in the API.

validateClass

public static void validateClass(Class<? extends UserDefinedFunction> functionClass)

Validates a UserDefinedFunction class for usage in the API.

Note: This is an initial validation to indicate common errors early. The concrete signature validation happens in the code generation when the actual DataTypes for arguments and result are known.