com.hammurapi.extract

Class MappedExtractor<T,V,C>

java.lang.Object

com.hammurapi.extract.MappedExtractor<T,V,C>

Type Parameters:

T -

V -

C -

All Implemented Interfaces:

Extractor<T,V,C>, FacadeExtractor<T,V,C>, Mappable<T,V,C>

Direct Known Subclasses:

MappedPredicate

public class MappedExtractor<T,V,C>
extends Object
implements FacadeExtractor<T,V,C>, Mappable<T,V,C>

Extractor which maps arguments to the target extractor.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	MappedExtractor(Extractor<T,V,C> target, int[] map)

Method Summary

Methods

Modifier and Type	Method and Description
ComparisonResult	compareTo(Extractor<T,V,C> other) Compares two extractors
V	extract(C context, Map<C,Map<Extractor<T,? super V,C>,? super V>> cache, T... obj) Extracts value.
double	getCost()
int[]	getMap()
Extractor<T,V,C>	getTarget()
boolean	isContextDependent()
Extractor<T,V,C>	map(int[] map) Applies mapping to extractor.
static <T,V,C> Extractor<T,V,C>	mapExtractor(Extractor<T,V,C> target, int[] map)
Set<Integer>	parameterIndices()
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

MappedExtractor

protected MappedExtractor(Extractor<T,V,C> target,
               int[] map)

Parameters:

target - Target extractor

map - Index map, e.g. if it is {5, 3} then the first argument of this extractor becomes the sixth argument of the target extractor and the second argument of this extractor becomes the 4th argument of the target extractor.

Method Detail

extract

public V extract(C context,
        Map<C,Map<Extractor<T,? super V,C>,? super V>> cache,
        T... obj)

Description copied from interface: Extractor

Extracts value.

Specified by:

extract in interface Extractor<T,V,C>

Parameters:

context - Extraction context. Extraction context may provide source for constants for comparison with object values.

cache - Cache of values extracted from the source object for the given context. Composite extractors can use cache to find already extracted values and to store extracted values. For example extractor which extracts object area as obj.getWidth()*obj.getHeight() may find that width was already extracted and getWidth() doesn't have to be invoked. So it invokes getHeight() and stores returned value to the cache. It also calculates object area and stores it to the cache. A particular cache instance is valid only for a particular obj array, i.e. it can be re-used between extractors but not between arguments.

obj - Source objects.

Returns:

Extracted value.

parameterIndices

public Set<Integer> parameterIndices()

Specified by:

parameterIndices in interface Extractor<T,V,C>

Returns:

Indexes of objects which this extractor uses for computations.

isContextDependent

public boolean isContextDependent()

Specified by:

isContextDependent in interface Extractor<T,V,C>

Returns:

True if extractor uses context for extraction. False if only object(s) are used.

compareTo

public ComparisonResult compareTo(Extractor<T,V,C> other)

Description copied from interface: Extractor

Compares two extractors

Specified by:

compareTo in interface Extractor<T,V,C>

Parameters:

other - Other extractor

Returns:

Comparison result.

toString

public String toString()

Overrides:

toString in class Object

getCost

public double getCost()

Specified by:

getCost in interface Extractor<T,V,C>

Returns:

Extractor evaluation cost. Cost is used for optimization of computation intensive algorithms. E.g. in Store it is used for selection of indices for query operations.

mapExtractor

public static <T,V,C> Extractor<T,V,C> mapExtractor(Extractor<T,V,C> target,
                                    int[] map)

map

public Extractor<T,V,C> map(int[] map)

Description copied from interface: Mappable

Applies mapping to extractor.

Specified by:

map in interface Mappable<T,V,C>

Returns:

Extractor with changed mapping or null if mapping is not possible.

getTarget

public Extractor<T,V,C> getTarget()

getMap

public int[] getMap()