Package 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:
Iterable<T>, IQueryable<T>, IQueryResult<T>
public class Collector<T> extends 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 Details

    • EMPTY_COLLECTOR

      public static final Collector<?> EMPTY_COLLECTOR

  • Constructor Details

    • Collector

      public Collector()
      Creates a new collector.

  • Method Details

    • 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 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 Iterator<T> iterator()
      Returns an iterator on the collected objects.
      Specified by:
      iterator in interface IQueryResult<T>
      Specified by:
      iterator in interface Iterable<T>
      Returns:
      an iterator of the collected objects.

    • size

      public int size()
      Returns the number of collected objects.

    • toArray

      public T[] toArray(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:
      ArrayStoreException - the runtime type of the specified array is not a super-type of the runtime type of every collected object

    • toSet

      public 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 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