svn commit: r948973 - /incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.utils/src/main/java/org/apache/clerezza/utils/IteratorMerger.java

[re...@apache.org]

Author: reto
Date: Thu May 27 20:33:45 2010
New Revision: 948973

URL: http://svn.apache.org/viewvc?rev=948973&view=rev
Log:
added IteratorMerger that flattens an Iterator of Iterators to an Iterator

Added:
    incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.utils/src/main/java/org/apache/clerezza/utils/IteratorMerger.java

Added: incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.utils/src/main/java/org/apache/clerezza/utils/IteratorMerger.java
URL: http://svn.apache.org/viewvc/incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.utils/src/main/java/org/apache/clerezza/utils/IteratorMerger.java?rev=948973&view=auto
==============================================================================
--- incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.utils/src/main/java/org/apache/clerezza/utils/IteratorMerger.java (added)
+++ incubator/clerezza/trunk/org.apache.clerezza.parent/org.apache.clerezza.utils/src/main/java/org/apache/clerezza/utils/IteratorMerger.java Thu May 27 20:33:45 2010
@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.clerezza.utils;
+
+import java.util.Iterator;
+
+/**
+ * Flattens an Iterator of Iterators to an Iterator
+ * 
+ * @author reto
+ */
+public class IteratorMerger<T> implements Iterator<T> {
+
+	private final Iterator<Iterator<T>> baseIterators;
+	private Iterator<T> current;
+
+	/**
+	 * constructs an iterator that will return the elements of the baseIterators
+	 * 
+	 * @param baseIterators
+	 */
+	public IteratorMerger(Iterator<Iterator<T>> baseIterators) {
+		this.baseIterators = baseIterators;
+		current = baseIterators.next();
+	}
+
+	private void updateCurrentIfNeeded() {
+		while (!current.hasNext()) {
+			if (baseIterators.hasNext()) {
+				current = baseIterators.next();
+			} else {
+				return;
+			}
+		}
+	}
+
+	@Override
+	public boolean hasNext() {
+		updateCurrentIfNeeded();
+		return current.hasNext();
+	}
+
+	@Override
+	public T next() {
+		updateCurrentIfNeeded();
+		return current.next();
+	}
+
+	@Override
+	public void remove() {
+		current.remove();
+	}
+
+}