org.apache.flink.api.table.runtime

Class ExpressionSelectFunction<I,O>

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.api.common.functions.RichMapFunction<I,O>

org.apache.flink.api.table.runtime.ExpressionSelectFunction<I,O>

All Implemented Interfaces:

Serializable, Function, MapFunction<I,O>, RichFunction

public class ExpressionSelectFunction<I,O>
extends RichMapFunction<I,O>

Proxy function that takes expressions. These are compiled upon runtime and calls to map() are forwarded to the compiled code.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ExpressionSelectFunction(CompositeType<I> inputType, CompositeType<O> resultType, scala.collection.Seq<Expression> outputFields, TableConfig config)

Method Summary

Modifier and Type	Method and Description
MapFunction<I,O>	compiledSelect()
O	map(I in) The mapping method.
void	open(Configuration c) Initialization method for the function.

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionSelectFunction

public ExpressionSelectFunction(CompositeType<I> inputType,
                                CompositeType<O> resultType,
                                scala.collection.Seq<Expression> outputFields,
                                TableConfig config)

Method Detail

compiledSelect

public MapFunction<I,O> compiledSelect()

open

public void open(Configuration c)

Description copied from interface: RichFunction

Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

The configuration object passed to the function can be used for configuration and initialization. The configuration contains all parameters that were configured on the function in the program composition.

 public class MyMapper extends FilterFunction<String> {
 
     private String searchString;
     
     public void open(Configuration parameters) {
         this.searchString = parameters.getString("foo");
     }
     
     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

By default, this method does nothing.

Specified by:

open in interface RichFunction

Overrides:

open in class AbstractRichFunction

Parameters:

c - The configuration containing the parameters attached to the contract.

See Also:

Configuration

map

public O map(I in)

Description copied from interface: MapFunction

The mapping method. Takes an element from the input data set and transforms it into exactly one element.

Specified by:

map in interface MapFunction<I,O>

Specified by:

map in class RichMapFunction<I,O>

Parameters:

in - The input value.

Returns:

The transformed value