1 files changed, 65 insertions, 0 deletions
diff --git a/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/internal/p2/ql/MatchIteratorFilter.java b/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/internal/p2/ql/MatchIteratorFilter.java
new file mode 100644
index 000000000..b8cfe2f75
--- /dev/null
+++ b/bundles/org.eclipse.equinox.p2.ql/src/org/eclipse/equinox/internal/p2/ql/MatchIteratorFilter.java
@@ -0,0 +1,65 @@
+/*******************************************************************************
+ * Copyright (c) 2009 Cloudsmith Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Cloudsmith Inc. - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.equinox.internal.p2.ql;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+/**
+ * An iterator filter using a boolean {@link #isMatch(Object)} method.
+ */
+public abstract class MatchIteratorFilter implements Iterator {
+	private static final Object NO_ELEMENT = new Object();
+
+	private final Iterator innerIterator;
+
+	private final Class instanceClass;
+
+	private Object nextObject = NO_ELEMENT;
+
+	public MatchIteratorFilter(Class instanceClass, Iterator iterator) {
+		this.instanceClass = instanceClass;
+		this.innerIterator = iterator;
+	}
+
+	public boolean hasNext() {
+		return positionNext();
+	}
+
+	public Object next() {
+		if (!positionNext())
+			throw new NoSuchElementException();
+
+		Object nxt = nextObject;
+		nextObject = NO_ELEMENT;
+		return nxt;
+	}
+
+	public void remove() {
+		throw new UnsupportedOperationException();
+	}
+
+	protected abstract boolean isMatch(Object val);
+
+	private boolean positionNext() {
+		if (nextObject != NO_ELEMENT)
+			return true;
+
+		while (innerIterator.hasNext()) {
+			Object nxt = innerIterator.next();
+			if (instanceClass.isInstance(nxt) && isMatch(nxt)) {
+				nextObject = nxt;
+				return true;
+			}
+		}
+		return false;
+	}
+}
+\ No newline at end of file