Clean-up IQueryResult and its implementations

bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/internal/p2/metadata/expression/QueryResult.java

@@ -14,31 +14,40 @@
 package org.eclipse.equinox.internal.p2.metadata.expression;
 
 import java.lang.reflect.Array;
-import java.util.*;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.equinox.p2.metadata.index.IIndexProvider;
 import org.eclipse.equinox.p2.query.IQuery;
 import org.eclipse.equinox.p2.query.IQueryResult;
 
 /**
- * A result optimized for dealing with iterators returned from
- * expression evaluation.
+ * A result optimized for dealing with iterators returned from expression
+ * evaluation.
  */
 public class QueryResult<T> implements IQueryResult<T> {
 
  private final IRepeatableIterator<T> iterator;
  private boolean firstUse = true;
 
  /**
- * Create an QueryResult based on the given iterator. The <code>oneShot</code> parameter
- * can be set to <code>true</code> if the returned instance is expected to be perused
- * only once. This will allow some optimizations since the result of the iteration doesn't
- * need to be copied in preparation for a second iteration.
+ * Create an QueryResult based on the given iterator. The <code>oneShot</code>
+ * parameter can be set to <code>true</code> if the returned instance is
+ * expected to be perused only once. This will allow some optimizations since
+ * the result of the iteration doesn't need to be copied in preparation for a
+ * second iteration.
  *
  * @param iterator The iterator to use as the result iterator.
  */
  public QueryResult(Iterator<T> iterator) {
- this.iterator = (iterator instanceof IRepeatableIterator<?>) ? (IRepeatableIterator<T>) iterator : RepeatableIterator.create(iterator);
+ this.iterator = (iterator instanceof IRepeatableIterator<T> repeatable) //
+ ? repeatable
+ : RepeatableIterator.create(iterator);
  }
 
  public QueryResult(Collection<T> collection) {
@@ -63,31 +72,26 @@ public Iterator<T> iterator() {
  @SuppressWarnings("unchecked")
  public T[] toArray(Class<T> clazz) {
  Object provider = iterator.getIteratorProvider();
- if (provider.getClass().isArray())
+ if (provider.getClass().isArray()) {
  return (T[]) provider;
-
- Collection<T> c = toUnmodifiableSet();
- return c.toArray((T[]) Array.newInstance(clazz, c.size()));
+ }
+ return toArray(toUnmodifiableSet(), clazz);
  }
 
  @Override
  @SuppressWarnings("unchecked")
  public Set<T> toSet() {
  Object provider = iterator.getIteratorProvider();
- if (provider instanceof Collection<?>)
- return new HashSet<>((Collection<T>) provider);
- if (provider instanceof IIndexProvider<?>)
- return iteratorToSet(((IIndexProvider<T>) provider).everything());
- if (provider.getClass().isArray()) {
+ if (provider instanceof Collection collection) {
+ return new HashSet<>(collection);
+ } else if (provider instanceof IIndexProvider indexProvider) {
+ return iteratorToSet(indexProvider.everything());
+ } else if (provider.getClass().isArray()) {
  T[] elems = (T[]) provider;
- int idx = elems.length;
- HashSet<T> copy = new HashSet<>(idx);
- while (--idx >= 0)
- copy.add(elems[idx]);
- return copy;
+ return new HashSet<>(Arrays.asList(elems));
+ } else if (provider instanceof Map<?, ?> map) {
+ return new HashSet<>((Set<T>) map.entrySet());
  }
- if (provider instanceof Map<?, ?>)
- return new HashSet<>((Set<T>) ((Map<?, ?>) provider).entrySet());
  return iteratorToSet(iterator());
  }
 
@@ -100,17 +104,25 @@ public IQueryResult<T> query(IQuery<T> query, IProgressMonitor monitor) {
  @SuppressWarnings("unchecked")
  public Set<T> toUnmodifiableSet() {
  Object provider = iterator.getIteratorProvider();
- if (provider instanceof Set<?>)
- return Collections.unmodifiableSet((Set<T>) provider);
- if (provider instanceof Map<?, ?>)
- return Collections.unmodifiableSet((Set<T>) ((Map<?, ?>) provider).entrySet());
+ if (provider instanceof Set set) {
+ return Collections.unmodifiableSet(set);
+ } else if (provider instanceof Map map) {
+ return Collections.unmodifiableSet((Set<T>) map.entrySet());
+ }
  return toSet();
  }
 
  private Set<T> iteratorToSet(Iterator<T> iter) {
- HashSet<T> set = new HashSet<>();
- while (iter.hasNext())
+ Set<T> set = new HashSet<>();
+ while (iter.hasNext()) {
  set.add(iter.next());
+ }
  return set;
  }
+
+ public static <T> T[] toArray(Collection<T> collection, Class<T> clazz) {
+ @SuppressWarnings("unchecked")
+ T[] arr = (T[]) Array.newInstance(clazz, collection == null ? 0 : collection.size());
+ return collection != null ? collection.toArray(arr) : arr;
+ }
 }

bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/CollectionResult.java

@@ -13,16 +13,18 @@
  *******************************************************************************/
 package org.eclipse.equinox.p2.query;
 
-import java.lang.reflect.Array;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
 import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.equinox.internal.p2.metadata.expression.QueryResult;
 
 /**
- * This class allows to adapt java collections to a p2 a query result and as such something queryable 
+ * This class allows to adapt java collections to a p2 a query result and as
+ * such something queryable
+ * 
  * @since 2.0
  */
 public class CollectionResult<T> implements IQueryResult<T> {
@@ -49,12 +51,7 @@ public Iterator<T> iterator() {
 
  @Override
  public T[] toArray(Class<T> clazz) {
- int size = collection.size();
- @SuppressWarnings("unchecked")
- T[] result = (T[]) Array.newInstance(clazz, size);
- if (size != 0)
- collection.toArray(result);
- return result;
+ return QueryResult.toArray(collection, clazz);
  }
 
  @Override

bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/Collector.java

@@ -14,7 +14,6 @@
  *******************************************************************************/
 package org.eclipse.equinox.p2.query;
 
-import java.lang.reflect.Array;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
@@ -23,6 +22,7 @@
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.NullProgressMonitor;
 import org.eclipse.equinox.internal.p2.metadata.Messages;
+import org.eclipse.equinox.internal.p2.metadata.expression.QueryResult;
 
 /**
  * A collector is a generic visitor that collects objects passed to it, and can
@@ -51,13 +51,6 @@ public static final <T> Collector<T> emptyCollector() {
  return (Collector<T>) EMPTY_COLLECTOR;
  }
 
- /**
- * Creates a new collector.
- */
- public Collector() {
- super();
- }
-
  /**
  * Accepts an object.
  * <p>
@@ -96,8 +89,9 @@ public void addAll(IQueryResult<T> queryResult) {
  * @return the collection being used to collect results.
  */
  protected Collection<T> getCollection() {
- if (collected == null)
+ if (collected == null) {
  collected = new HashSet<>();
+ }
  return collected;
  }
 
@@ -119,7 +113,7 @@ public boolean isEmpty() {
  */
  @Override
  public Iterator<T> iterator() {
- return collected == null ? Collections.<T>emptyList().iterator() : collected.iterator();
+ return collected == null ? Collections.emptyIterator() : collected.iterator();
  }
 
  /**
@@ -140,18 +134,13 @@ public int size() {
  */
  @Override
  public T[] toArray(Class<T> clazz) {
- int size = collected == null ? 0 : collected.size();
- @SuppressWarnings("unchecked")
- T[] result = (T[]) Array.newInstance(clazz, size);
- if (size != 0)
- collected.toArray(result);
- return result;
+ return QueryResult.toArray(collected, clazz);
  }
 
  /**
  * Returns a copy of the collected objects.
  * 
- * @return An unmodifiable collection of the collected objects
+ * @return An modifiable collection of the collected objects
  */
  @Override
  public Set<T> toSet() {
@@ -164,8 +153,9 @@ public Set<T> toSet() {
  @Override
  public IQueryResult<T> query(IQuery<T> query, IProgressMonitor monitor) {
  IQueryResult<T> result;
- if (monitor == null)
+ if (monitor == null) {
  monitor = new NullProgressMonitor();
+ }
  try {
  monitor.beginTask(Messages.performing_subquery, 1);
  result = query.perform(iterator());

bundles/org.eclipse.equinox.p2.metadata/src/org/eclipse/equinox/p2/query/IQueryResult.java

@@ -18,25 +18,26 @@
 import java.util.Set;
 
 /**
- * An IQueryResult represents the results of a query. 
+ * An IQueryResult represents the results of a query.
  * 
  * @since 2.0
  */
 public interface IQueryResult<T> extends IQueryable<T>, Iterable<T> {
  /**
- * Returns whether this QueryResult is empty.
- * @return <code>true</code> if this QueryResult has accepted any results,
- * and <code>false</code> otherwise.
+ * Returns whether this QueryResult is empty.
+ * 
+ * @return <code>true</code> if this QueryResult has accepted any results, and
+ * <code>false</code> otherwise.
  */
- public boolean isEmpty();
+ boolean isEmpty();
 
  /**
  * Returns an iterator on the collected objects.
  * 
  * @return an iterator of the collected objects.
  */
  @Override
- public Iterator<T> iterator();
+ Iterator<T> iterator();
 
  /**
  * Returns the collected objects as an array
@@ -46,18 +47,20 @@ public interface IQueryResult<T> extends IQueryable<T>, Iterable<T> {
  * @throws ArrayStoreException the runtime type of the specified array is
  * not a super-type of the runtime type of every collected object
  */
- public T[] toArray(Class<T> clazz);
+ T[] toArray(Class<T> clazz);
 
  /**
- * Creates a new Set copy with the contents of this query result. The
- * copy can be altered without any side effects on its origin.
+ * Creates a new Set copy with the contents of this query result. The copy can
+ * be altered without any side effects on its origin.
+ * 
  * @return A detached copy of the result.
  */
- public Set<T> toSet();
+ Set<T> toSet();
 
  /**
  * Returns a Set backed by this query result. The set is immutable.
+ * 
  * @return A Set backed by this query result.
  */
- public Set<T> toUnmodifiableSet();
+ Set<T> toUnmodifiableSet();
 }