Package edu.harvard.seas.pl.abcdatalog.util.datastructures

Class ConcurrentFactIndexer<T extends Iterable<PositiveAtom>>

java.lang.Object

edu.harvard.seas.pl.abcdatalog.util.datastructures.ConcurrentFactIndexer<T>

Type Parameters:

T - the container type

All Implemented Interfaces:

FactIndexer, IndexableFactCollection

public class ConcurrentFactIndexer<T extends Iterable<PositiveAtom>>
extends Object
implements FactIndexer

An index that holds facts. The facts are indexed by predicate symbol and then by the constants in each argument position. The indexer is parameterized by the type of the container that ultimately holds the facts (i.e., all facts that belong to the same index are added to the same container).

In the presence of multiple threads, the indexer can momentarily be in an inconsistent state. However, after the add method returns having been invoked with a fact f, the indexer will be consistent with respect to f, meaning that f is properly indexed and that it is visible as such to all threads. (This only holds, of course, if the provided container type is thread safe.)

Constructor Summary

Constructors

Constructor	Description
ConcurrentFactIndexer(Supplier<T> generator, BiConsumer<T,PositiveAtom> addFunc)	Creates a new fact indexer.
ConcurrentFactIndexer(Supplier<T> generator, BiConsumer<T,PositiveAtom> addFunc, Supplier<T> empty)	Creates a new fact indexer.

Method Summary

Modifier and Type	Method	Description
void	add(PositiveAtom fact)	Adds a fact to this indexer.
void	addAll(IndexableFactCollection that)	Add all the facts from an indexable fact collection to this index.
void	addAll(Iterable<PositiveAtom> facts)	Adds the facts to the index.
void	clear()	Clears this index.
ConcurrentFactIndexer<T>	getCopy()
Set<PredicateSym>	getPreds()	Returns the set of the predicate symbols represented in this collection.
T	indexInto(PositiveAtom a)	Returns the atoms in the collection that potentially "match" the provided atom.
T	indexInto(PositiveAtom a, ConstOnlySubstitution s)	Returns the atoms in the collection that potentially "match" the provided atom, after the given substitution has been applied.
T	indexInto(PredicateSym pred)	Returns the atoms in the collection with the given predicate symbol.
boolean	isEmpty()	Returns whether the collection is empty.

Methods inherited from class java.lang.Object

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

Constructor Details

ConcurrentFactIndexer

public ConcurrentFactIndexer(Supplier<T> generator,
 BiConsumer<T,PositiveAtom> addFunc)

Creates a new fact indexer.

Parameters:

generator - an anonymous function that returns a container

addFunc - an anonymous function that adds a fact to a container

ConcurrentFactIndexer

public ConcurrentFactIndexer(Supplier<T> generator,
 BiConsumer<T,PositiveAtom> addFunc,
 Supplier<T> empty)

Creates a new fact indexer.

Parameters:

generator - an anonymous function that returns a container

addFunc - an anonymous function that adds a fact to a container

empty - an anonymous function that returns an empty container (such as a static instance)

Method Details

add

public void add(PositiveAtom fact)

Adds a fact to this indexer.

Specified by:

add in interface FactIndexer

Parameters:

fact - the fact

addAll

public void addAll(Iterable<PositiveAtom> facts)

Adds the facts to the index.

Specified by:

addAll in interface FactIndexer

Parameters:

facts - the facts

indexInto

public T indexInto(PositiveAtom a)

Description copied from interface: IndexableFactCollection

Returns the atoms in the collection that potentially "match" the provided atom. There is no guarantee that the returned atoms can actually be unified with the provided atom.

Specified by:

indexInto in interface IndexableFactCollection

Parameters:

a - the atom to match

Returns:

the matching facts

indexInto

public T indexInto(PositiveAtom a,
 ConstOnlySubstitution s)

Description copied from interface: IndexableFactCollection

Returns the atoms in the collection that potentially "match" the provided atom, after the given substitution has been applied. There is no guarantee that the returned atoms can actually be unified with the provided atom.

Specified by:

indexInto in interface IndexableFactCollection

Parameters:

a - the atom to match

Returns:

the matching facts

indexInto

public T indexInto(PredicateSym pred)

Description copied from interface: IndexableFactCollection

Returns the atoms in the collection with the given predicate symbol.

Specified by:

indexInto in interface IndexableFactCollection

Parameters:

pred - the predicate symbol

Returns:

the matching facts

clear

public void clear()

Clears this index.

isEmpty

public boolean isEmpty()

Description copied from interface: IndexableFactCollection

Returns whether the collection is empty.

Specified by:

isEmpty in interface IndexableFactCollection

Returns:

whether the collection is empty

getCopy

public ConcurrentFactIndexer<T> getCopy()

getPreds

public Set<PredicateSym> getPreds()

Description copied from interface: IndexableFactCollection

Returns the set of the predicate symbols represented in this collection.

Specified by:

getPreds in interface IndexableFactCollection

Returns:

the predicate symbols

addAll

public void addAll(IndexableFactCollection that)

Add all the facts from an indexable fact collection to this index.

Parameters:

that - the indexable fact collection