Author: pete.muir(a)jboss.org Date: 2009-07-01 11:48:31 -0400 (Wed, 01 Jul 2009) New Revision: 2944 Added: ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/Iterators.java ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/UnmodifiableIterator.java Log: Add an iterator concat function Added: ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/Iterators.java =================================================================== --- ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/Iterators.java (rev 0) +++ ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/Iterators.java 2009-07-01 15:48:31 UTC (rev 2944) @@ -0,0 +1,122 @@ +/* + * + * JBoss, Home of Professional Open Source + * Copyright 2008, Red Hat Middleware LLC, and individual contributors + * by the @authors tag. See the copyright.txt in the distribution for a + * full listing of individual contributors. + * + * Copyright (C) 2007 Google Inc. + * + * Licensed 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.jboss.webbeans.util.collections; + +import java.util.Iterator; +import java.util.NoSuchElementException; + +/** + * @author Pete Muir + * @author Kevin Bourrillion + * @author Scott Bonneau + * + */ +public class Iterators +{ + + static final UnmodifiableIterator<Object> EMPTY_ITERATOR = new UnmodifiableIterator<Object>() + { + public boolean hasNext() + { + return false; + } + + public Object next() + { + throw new NoSuchElementException(); + } + }; + + /** Returns the empty {@code Iterator}. */ + // Casting to any type is safe since there are no actual elements. + @SuppressWarnings("unchecked") + public static <T> UnmodifiableIterator<T> emptyIterator() + { + return (UnmodifiableIterator<T>) EMPTY_ITERATOR; + } + + public static <T> Iterable<T> concat(final Iterable<? extends Iterable<? extends T>> inputs) + { + return new Iterable<T>() + { + + public Iterator<T> iterator() + { + return concat(inputs.iterator()); + } + + }; + } + + /** + * Combines multiple iterators into a single iterator. The returned iterator + * iterates across the elements of each iterator in {@code inputs}. The input + * iterators are not polled until necessary. + * + * <p> + * The returned iterator supports {@code remove()} when the corresponding + * input iterator supports it. The methods of the returned iterator may throw + * {@code NullPointerException} if any of the input iterators are null. + */ + public static <T> Iterator<T> concat(final Iterator<? extends Iterable<? extends T>> inputs) + { + if (inputs == null) + { + throw new NullPointerException(); + } + + return new Iterator<T>() + { + Iterator<? extends T> current = emptyIterator(); + Iterator<? extends T> removeFrom; + + public boolean hasNext() + { + boolean currentHasNext; + while (!(currentHasNext = current.hasNext()) && inputs.hasNext()) + { + current = inputs.next().iterator(); + } + return currentHasNext; + } + + public T next() + { + if (!hasNext()) + { + throw new NoSuchElementException(); + } + removeFrom = current; + return current.next(); + } + + public void remove() + { + if (removeFrom == null) + { + throw new IllegalStateException("no calls to next() since last call to remove()"); + } + removeFrom.remove(); + removeFrom = null; + } + }; + } + +} Property changes on: ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/Iterators.java ___________________________________________________________________ Name: svn:mime-type + text/plain Added: ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/UnmodifiableIterator.java =================================================================== --- ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/UnmodifiableIterator.java (rev 0) +++ ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/UnmodifiableIterator.java 2009-07-01 15:48:31 UTC (rev 2944) @@ -0,0 +1,36 @@ +/* + * Copyright (C) 2008 Google Inc. + * + * Licensed 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.jboss.webbeans.util.collections; + +import java.util.Iterator; + +/** + * An iterator that does not support {@link #remove}. + * + * @author Jared Levy + */ +public abstract class UnmodifiableIterator<E> implements Iterator<E> { + /** + * Guaranteed to throw an exception and leave the underlying data unmodified. + * + * @throws UnsupportedOperationExcepti! on always + */ + public final void remove() { + throw new UnsupportedOperationException(); + } +} + Property changes on: ri/trunk/impl/src/main/java/org/jboss/webbeans/util/collections/UnmodifiableIterator.java ___________________________________________________________________ Name: svn:mime-type + text/plain