org.apache.beam.sdk.extensions.sql.impl.interpreter.operator.collection

Class BeamSqlSingleElementExpression

java.lang.Object

org.apache.beam.sdk.extensions.sql.impl.interpreter.operator.BeamSqlExpression

org.apache.beam.sdk.extensions.sql.impl.interpreter.operator.collection.BeamSqlSingleElementExpression

All Implemented Interfaces:

java.io.Serializable

public class BeamSqlSingleElementExpression
extends BeamSqlExpression

Implements ELEMENT(collection) operation which returns the single element from the collection.

Throws if there is more than one element. Returns null if collection is empty.

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.beam.sdk.extensions.sql.impl.interpreter.operator.BeamSqlExpression

operands, outputType

Constructor Summary

Constructors

Constructor and Description
BeamSqlSingleElementExpression(java.util.List<BeamSqlExpression> operands, org.apache.calcite.sql.type.SqlTypeName sqlTypeName)

Method Summary

Modifier and Type	Method and Description
boolean	accept() assertion to make sure the input and output are supported in this expression.
BeamSqlPrimitive	evaluate(Row inputRow, BoundedWindow window, BeamSqlExpressionEnvironment env) Apply input record Row with BoundedWindow to this expression, the output value is wrapped with BeamSqlPrimitive.

Methods inherited from class org.apache.beam.sdk.extensions.sql.impl.interpreter.operator.BeamSqlExpression

getOperands, getOutputType, numberOfOperands, op, opType, opValueEvaluated

Methods inherited from class java.lang.Object

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

Constructor Detail

BeamSqlSingleElementExpression

public BeamSqlSingleElementExpression(java.util.List<BeamSqlExpression> operands,
                                      org.apache.calcite.sql.type.SqlTypeName sqlTypeName)

Method Detail

accept

public boolean accept()

Description copied from class: BeamSqlExpression

assertion to make sure the input and output are supported in this expression.

Specified by:

accept in class BeamSqlExpression

evaluate

public BeamSqlPrimitive evaluate(Row inputRow,
                                 BoundedWindow window,
                                 BeamSqlExpressionEnvironment env)

Description copied from class: BeamSqlExpression

Apply input record Row with BoundedWindow to this expression, the output value is wrapped with BeamSqlPrimitive.

Specified by:

evaluate in class BeamSqlExpression