org.cojen.tupl

Interface Transformer

All Known Subinterfaces:

Filter

public interface Transformer

Interface which supports filtering and transforming the entries within a View. For pure filtering, consider implementing a Filter instead.

See Also:

View.viewTransformed

Method Summary

Modifier and Type	Method and Description
default byte[]	inverseTransformKey(byte[] tkey) Apply an inverse transformation of the given key, if supported.
default byte[]	inverseTransformKeyGt(byte[] tkey) Apply an inverse transformation of the given key, strictly greater than the one given.
default byte[]	inverseTransformKeyLt(byte[] tkey) Apply an inverse transformation of the given key, strictly less than the one given.
byte[]	inverseTransformValue(byte[] tvalue, byte[] key, byte[] tkey) Apply an inverse transformation of the given value, if supported.
default boolean	requireValue() Returns true by default, indicating that the transform methods always require a value instance to be provided.
default Ordering	transformedOrdering(Ordering original) Returns the natural ordering of keys, after they have been transformed.
default byte[]	transformKey(byte[] key, byte[] value) Transform or filter out the given key.
byte[]	transformValue(byte[] value, byte[] key, byte[] tkey) Transform or filter out the given value.

Method Detail

requireValue

default boolean requireValue()

Returns true by default, indicating that the transform methods always require a value instance to be provided.

Returns:

true if a value must always be passed into the transform methods

transformValue

byte[] transformValue(byte[] value,
                      byte[] key,
                      byte[] tkey)
               throws IOException

Transform or filter out the given value. This method is only called after loading a value from a view.

Parameters:

value - nullable value to transform

key - non-null untransformed key associated with the value

tkey - non-null transformed key associated with the value

Returns:

transformed value or null to discard entry

Throws:

IOException

inverseTransformValue

byte[] inverseTransformValue(byte[] tvalue,
                             byte[] key,
                             byte[] tkey)
                      throws ViewConstraintException,
                             IOException

Apply an inverse transformation of the given value, if supported. This method is only called when attempting to store the value into the view.

Parameters:

tvalue - nullable value to transform

key - non-null untransformed key associated with the value

tkey - non-null transformed key associated with the value

Returns:

inverse transformed value, or null to delete the value

Throws:

ViewConstraintException - if inverse transformation of given value is not supported

IOException

transformKey

default byte[] transformKey(byte[] key,
                            byte[] value)
                     throws IOException

Transform or filter out the given key. This method is only called after loading a value from a view. Default implementation returns the same key.

Parameters:

key - non-null key to transform

value - nullable value associated with the key

Returns:

transformed key or null to discard entry

Throws:

IOException

inverseTransformKey

default byte[] inverseTransformKey(byte[] tkey)

Apply an inverse transformation of the given key, if supported. This method can be called for load and store operations. Default implementation returns the same key.

Parameters:

tkey - non-null key

Returns:

inverse transformed key or null if inverse transformation of given key is not supported

inverseTransformKeyGt

default byte[] inverseTransformKeyGt(byte[] tkey)

Apply an inverse transformation of the given key, strictly greater than the one given. This method is only called after the regular inverse transformation has been attempted. Default implementation increments the key by the minimum amount and then calls inverseTransformKey.

Parameters:

tkey - non-null key

Returns:

inverse transformed key or null if inverse transformation of given key is not supported

inverseTransformKeyLt

default byte[] inverseTransformKeyLt(byte[] tkey)

Apply an inverse transformation of the given key, strictly less than the one given. This method is only called after the regular inverse transformation has been attempted. Default implementation decrements the key by the minimum amount and then calls inverseTransformKey.

Parameters:

tkey - non-null key

Returns:

inverse transformed key or null if inverse transformation of given key is not supported

transformedOrdering

default Ordering transformedOrdering(Ordering original)

Returns the natural ordering of keys, after they have been transformed. Default implementation returns the same ordering.

Parameters:

original - natural ordering of view before transformation