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

java.lang.Object
  org.apache.derby.impl.sql.compile.UserAggregateDefinition

All Implemented Interfaces:

AggregateDefinition

public class UserAggregateDefinition
extends java.lang.Object
implements AggregateDefinition

Definition for user-defined aggregates.

Field Summary

private AliasDescriptor	_alias
private static int	AGGREGATOR_PARAM_COUNT
private static int	AGGREGATOR_TYPE
private static java.lang.String	DERBY_BYTE_ARRAY_NAME
private static int	INPUT_TYPE
private static int	RETURN_TYPE

Constructor Summary

UserAggregateDefinition(AliasDescriptor alias)
Conjure out of thin air.

Method Summary

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

Methods inherited from class java.lang.Object

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

Field Detail

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 java.lang.String DERBY_BYTE_ARRAY_NAME

See Also:

Constant Field Values

_alias

private AliasDescriptor _alias

Constructor Detail

UserAggregateDefinition

public UserAggregateDefinition(AliasDescriptor alias)

Conjure out of thin air.

Method Detail

getAliasDescriptor

public AliasDescriptor getAliasDescriptor()

Get the wrapped alias descriptor

getAggregator

public final DataTypeDescriptor getAggregator(DataTypeDescriptor inputType,
                                              java.lang.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(java.lang.Class actualClass,
                              java.lang.Class expectedClass,
                              java.lang.String sqlState)
                       throws StandardException

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

Throws:

StandardException

castInputValue

public final ValueNode castInputValue(ValueNode inputValue,
                                      NodeFactory nodeFactory,
                                      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 java.lang.Class getJavaClass(ClassFactory classFactory,
                                     DataTypeDescriptor dtd)
                              throws StandardException,
                                     java.lang.ClassNotFoundException

Get the Java class corresponding to a Derby datatype.

Throws:

StandardException

java.lang.ClassNotFoundException

aggregatorInstantiation

private StandardException aggregatorInstantiation(java.lang.Throwable t)

Make a "Could not instantiate aggregator" exception.