com.hammurapi.extract

Class ExtractorBase<T,V,C>

java.lang.Object

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

Type Parameters:

T -

V -

All Implemented Interfaces:

Extractor<T,V,C>

Direct Known Subclasses:

AbstractExtractor, Add, And, CommutativeAnd, CommutativeOr, ComparisonPredicate, CompositeExtractorBase, Constant, Divide, MethodExtractor, Multiply, Or, ScriptingPredicate, Subtract

public abstract class ExtractorBase<T,V,C>
extends Object
implements Extractor<T,V,C>

Base class for extractors, implements value caching.

Field Summary

Fields

Modifier and Type	Field and Description
protected double	cost
protected TimeUnit	costUnit
protected double	initialCost
protected long	invocations
protected boolean	nanos
protected double	totalCost

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ExtractorBase(double initialCost, TimeUnit costUnit)

Method Summary

Methods

Modifier and Type	Method and Description
ComparisonResult	compareTo(Extractor<T,V,C> other) Basic comparisons with True and False.
protected Map<Extractor<T,? super V,C>,? super V>	createCacheEntry()
boolean	equals(Object obj)
V	extract(C context, Map<C,Map<Extractor<T,? super V,C>,? super V>> cache, T... obj) Extracts value.
protected abstract V	extractInternal(C context, Map<C,Map<Extractor<T,? super V,C>,? super V>> cache, T... obj)
double	getCost()

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.hammurapi.extract.Extractor

isContextDependent, parameterIndices

Field Detail

costUnit

protected TimeUnit costUnit

invocations

protected long invocations

totalCost

protected double totalCost

nanos

protected boolean nanos

cost

protected double cost

initialCost

protected double initialCost

Constructor Detail

ExtractorBase

protected ExtractorBase(double initialCost,
             TimeUnit costUnit)

Parameters:

initialCost - Initial cost. If positive, this value is added to the calculated cost. If costUnit is null, then cost is always equal to the initial cost. If negative and time unit is not null, then absolute value is used as first measurement of cost.

costUnit - If this argument is not null, then extractor cost is calculated as average time to execute extractInternal() method in specified time unit. If time unit is nanoseconds or microseconds, then System.nanoTime() method is used for measurement, otherwise Systsm.currentTimeMillis() is used.

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.

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.

compareTo

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

Basic comparisons with True and False.

Specified by:

compareTo in interface Extractor<T,V,C>

Parameters:

otherPredicate -

Returns:

extractInternal

protected abstract V extractInternal(C context,
                Map<C,Map<Extractor<T,? super V,C>,? super V>> cache,
                T... obj)

createCacheEntry

protected Map<Extractor<T,? super V,C>,? super V> createCacheEntry()

equals

public boolean equals(Object obj)

Overrides:

equals in class Object