org.eclipse.equinox.p2.query

Class Collector<T>

java.lang.Object

org.eclipse.equinox.p2.query.Collector<T>

Type Parameters:

T - The type of object accepted by this collector

All Implemented Interfaces:

java.lang.Iterable<T>, IQueryable<T>, IQueryResult<T>

public class Collector<T>
extends java.lang.Object
implements IQueryResult<T>

A collector is a generic visitor that collects objects passed to it, and can then express the result of the visit in various forms. The collector can also short-circuit a traversal by returning false from its accept(Object) method.

This default collector just accepts all objects passed to it. Clients may subclass to perform different processing on the objects passed to it.

Since:

2.0

Field Summary

Fields

Modifier and Type	Field and Description
static Collector<?>	EMPTY_COLLECTOR

Constructor Summary

Constructors

Constructor and Description
Collector() Creates a new collector.

Method Summary

Modifier and Type	Method and Description
boolean	accept(T object) Accepts an object.
void	addAll(IQueryResult<T> queryResult) Adds the elements from one collector to this collector
static <T> Collector<T>	emptyCollector()
protected java.util.Collection<T>	getCollection() Returns the collection that is being used to collect results.
boolean	isEmpty() Returns whether this collector is empty.
java.util.Iterator<T>	iterator() Returns an iterator on the collected objects.
IQueryResult<T>	query(IQuery<T> query, IProgressMonitor monitor) Performs a query on this results of this collector.
int	size() Returns the number of collected objects.
T[]	toArray(java.lang.Class<T> clazz) Returns the collected objects as an array
java.util.Set<T>	toSet() Returns a copy of the collected objects.
java.util.Set<T>	toUnmodifiableSet() Returns the collected objects as an immutable collection.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

EMPTY_COLLECTOR

public static final Collector<?> EMPTY_COLLECTOR

Constructor Detail

Collector

public Collector()

Creates a new collector.

Method Detail

emptyCollector

public static final <T> Collector<T> emptyCollector()

accept

public boolean accept(T object)

Accepts an object.

This default implementation adds the objects to a list. Clients may override this method to perform additional filtering, add different objects to the list, short-circuit the traversal, or process the objects directly without collecting them.

Parameters:

object - the object to collect or visit

Returns:

true if the traversal should continue, or false to indicate the traversal should stop.

addAll

public void addAll(IQueryResult<T> queryResult)

Adds the elements from one collector to this collector

Parameters:

queryResult - The collector from which the elements should be retrieved

getCollection

protected java.util.Collection<T> getCollection()

Returns the collection that is being used to collect results. Unlike toSet(), this returns the actual modifiable collection that is being used to store results. The return value is only intended to be used within subclasses and should not be exposed outside of a collection class.

Returns:

the collection being used to collect results.

isEmpty

public boolean isEmpty()

Returns whether this collector is empty.

Specified by:

isEmpty in interface IQueryResult<T>

Returns:

true if this collector has accepted any results, and false otherwise.

iterator

public java.util.Iterator<T> iterator()

Returns an iterator on the collected objects.

Specified by:

iterator in interface java.lang.Iterable<T>

Specified by:

iterator in interface IQueryResult<T>

Returns:

an iterator of the collected objects.

size

public int size()

Returns the number of collected objects.

toArray

public T[] toArray(java.lang.Class<T> clazz)

Returns the collected objects as an array

Specified by:

toArray in interface IQueryResult<T>

Parameters:

clazz - The type of array to return

Returns:

The array of results

Throws:

java.lang.ArrayStoreException - the runtime type of the specified array is not a super-type of the runtime type of every collected object

toSet

public java.util.Set<T> toSet()

Returns a copy of the collected objects.

Specified by:

toSet in interface IQueryResult<T>

Returns:

An unmodifiable collection of the collected objects

query

public IQueryResult<T> query(IQuery<T> query,
                             IProgressMonitor monitor)

Performs a query on this results of this collector.

Specified by:

query in interface IQueryable<T>

Parameters:

query - The query to perform

monitor - a progress monitor, or null if progress reporting is not desired

Returns:

The collector argument

toUnmodifiableSet

public java.util.Set<T> toUnmodifiableSet()

Returns the collected objects as an immutable collection.

Specified by:

toUnmodifiableSet in interface IQueryResult<T>

Returns:

An unmodifiable collection of the collected objects