Class UserAggregateDefinition

java.lang.Object

org.apache.derby.impl.sql.compile.UserAggregateDefinition

All Implemented Interfaces:

AggregateDefinition

class UserAggregateDefinition
extends Object
implements AggregateDefinition

Definition for user-defined aggregates.

Field Summary

Fields

Modifier and Type	Field	Description
private AliasDescriptor	_alias	////////////////////////////////////////////////////////////////////////////////
private static final int	AGGREGATOR_PARAM_COUNT
private static final int	AGGREGATOR_TYPE
private static final String	DERBY_BYTE_ARRAY_NAME
private static final int	INPUT_TYPE	////////////////////////////////////////////////////////////////////////////////
private static final int	RETURN_TYPE

Constructor Summary

Constructors

Constructor	Description
UserAggregateDefinition(AliasDescriptor alias)	Conjure out of thin air.

Method Summary

Modifier and Type	Method	Description
private StandardException	aggregatorInstantiation(Throwable t)	Make a "Could not instantiate aggregator" exception.
(package private) final ValueNode	castInputValue(ValueNode inputValue, ContextManager cm)	Wrap the input operand in an implicit CAST node as necessary in order to coerce it the correct type for the aggregator.
final DataTypeDescriptor	getAggregator(DataTypeDescriptor inputType, StringBuffer aggregatorClass)	Determines the result datatype and verifies that the input datatype is correct.
AliasDescriptor	getAliasDescriptor()	Get the wrapped alias descriptor
private Class<?>	getJavaClass(ClassFactory classFactory, DataTypeDescriptor dtd)	Get the Java class corresponding to a Derby datatype.
private void	vetCompatibility(Class<?> actualClass, Class<?> expectedClass, String sqlState)	Verify that an actual type is compatible with the expected type.

Methods inherited from class Object

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

Field Details

INPUT_TYPE

private static final int INPUT_TYPE

////////////////////////////////////////////////////////////////////////////////

See Also:

• Constant Field Values

RETURN_TYPE

private static final int RETURN_TYPE

See Also:

• Constant Field Values

AGGREGATOR_TYPE

private static final int AGGREGATOR_TYPE

See Also:

• Constant Field Values

AGGREGATOR_PARAM_COUNT

private static final int AGGREGATOR_PARAM_COUNT

See Also:

• Constant Field Values

DERBY_BYTE_ARRAY_NAME

private static final String DERBY_BYTE_ARRAY_NAME

See Also:

• Constant Field Values

_alias

private AliasDescriptor _alias

////////////////////////////////////////////////////////////////////////////////

Constructor Details

UserAggregateDefinition

public UserAggregateDefinition(AliasDescriptor alias)

Conjure out of thin air.

Method Details

getAliasDescriptor

public AliasDescriptor getAliasDescriptor()

Get the wrapped alias descriptor

getAggregator

public final DataTypeDescriptor getAggregator(DataTypeDescriptor inputType,
 StringBuffer aggregatorClass)
                                       throws StandardException

Determines the result datatype and verifies that the input datatype is correct.

Specified by:

getAggregator in interface AggregateDefinition

Parameters:

inputType - the input type

aggregatorClass - (Output arg) the name of the Derby execution-time class which wraps the aggregate logic

Returns:

the result type of the user-defined aggregator

Throws:

StandardException

See Also:

• TypeDescriptor

vetCompatibility

private void vetCompatibility(Class<?> actualClass,
 Class<?> expectedClass,
 String sqlState)
                       throws StandardException

Verify that an actual type is compatible with the expected type.

Throws:

StandardException

castInputValue

final ValueNode castInputValue(ValueNode inputValue,
 ContextManager cm)
                        throws StandardException

Wrap the input operand in an implicit CAST node as necessary in order to coerce it the correct type for the aggregator. Return null if no cast is necessary.

Throws:

StandardException

getJavaClass

private Class<?> getJavaClass(ClassFactory classFactory,
 DataTypeDescriptor dtd)
                       throws StandardException,
ClassNotFoundException

Get the Java class corresponding to a Derby datatype.

Throws:

StandardException

ClassNotFoundException

aggregatorInstantiation

private StandardException aggregatorInstantiation(Throwable t)

Make a "Could not instantiate aggregator" exception.