com.hammurapi.extract

Class True<T,C>

java.lang.Object

com.hammurapi.extract.True<T,C>

Type Parameters:

T -

C -

All Implemented Interfaces:

Extractor<T,Boolean,C>, Predicate<T,C>

public class True<T,C>
extends Object
implements Predicate<T,C>

Predicate which always evaluates to true. This predicate is primarily used for comparison

Method Summary

Methods

Modifier and Type	Method and Description
ComparisonResult	compareTo(Extractor<T,Boolean,C> otherPredicate) Compares two extractors
Boolean	extract(C context, Map<C,Map<Extractor<T,? super Boolean,C>,? super Boolean>> cache, T... obj) Extracts value.
double	getCost()
static <T,C> True<T,C>	getInstance()
boolean	isContextDependent()
Set<Integer>	parameterIndices()
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static <T,C> True<T,C> getInstance()

compareTo

public ComparisonResult compareTo(Extractor<T,Boolean,C> otherPredicate)

Description copied from interface: Extractor

Compares two extractors

Specified by:

compareTo in interface Extractor<T,Boolean,C>

Parameters:

otherPredicate - Other extractor

Returns:

Comparison result.

extract

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

Description copied from interface: Extractor

Extracts value.

Specified by:

extract in interface Extractor<T,Boolean,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.

isContextDependent

public boolean isContextDependent()

Specified by:

isContextDependent in interface Extractor<T,Boolean,C>

Returns:

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

parameterIndices

public Set<Integer> parameterIndices()

Specified by:

parameterIndices in interface Extractor<T,Boolean,C>

Returns:

Indexes of objects which this extractor uses for computations.

toString

public String toString()

Overrides:

toString in class Object

getCost

public double getCost()

Specified by:

getCost in interface Extractor<T,Boolean,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.