| /* |
| * 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.jclouds.collect; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import java.util.Iterator; |
| |
| import com.google.common.annotations.Beta; |
| import com.google.common.base.MoreObjects; |
| import com.google.common.base.Objects; |
| import com.google.common.base.Supplier; |
| import com.google.common.collect.AbstractIterator; |
| import com.google.common.collect.FluentIterable; |
| import com.google.common.collect.Iterators; |
| import com.google.common.collect.UnmodifiableIterator; |
| |
| /** |
| * continues to supply iterables until the last was empty |
| * |
| * @param <E> |
| */ |
| @Beta |
| public class AdvanceUntilEmptyIterable<E> extends FluentIterable<FluentIterable<E>> { |
| |
| public static <E> AdvanceUntilEmptyIterable<E> create(Supplier<FluentIterable<E>> nextIterable) { |
| return new AdvanceUntilEmptyIterable<E>(nextIterable); |
| } |
| |
| private final AdvanceUntilEmptyIterator<E> iterator; |
| |
| protected AdvanceUntilEmptyIterable(Supplier<FluentIterable<E>> nextIterable) { |
| this.iterator = new AdvanceUntilEmptyIterator<E>(checkNotNull(nextIterable, "next iterable")); |
| } |
| |
| @Override |
| public Iterator<FluentIterable<E>> iterator() { |
| return iterator; |
| } |
| |
| private static class AdvanceUntilEmptyIterator<E> extends AbstractIterator<FluentIterable<E>> { |
| |
| private final Supplier<FluentIterable<E>> nextIterable; |
| private transient FluentIterable<E> current; |
| private transient boolean unread = true; |
| |
| private AdvanceUntilEmptyIterator(Supplier<FluentIterable<E>> nextIterable) { |
| this.nextIterable = checkNotNull(nextIterable, "next iterable"); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| protected FluentIterable<E> computeNext() { |
| if (unread) |
| try { |
| return current = nextIterable.get(); |
| } finally { |
| unread = false; |
| } |
| else if (!current.isEmpty()) |
| return current = nextIterable.get(); |
| else |
| return endOfData(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public int hashCode() { |
| return Objects.hashCode(current, unread); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public boolean equals(Object obj) { |
| if (this == obj) |
| return true; |
| if (obj == null || getClass() != obj.getClass()) |
| return false; |
| AdvanceUntilEmptyIterator<?> other = AdvanceUntilEmptyIterator.class.cast(obj); |
| return Objects.equal(this.current, other.current) && Objects.equal(this.unread, other.unread); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return MoreObjects.toStringHelper("").omitNullValues().add("current", current).add("unread", unread).toString(); |
| } |
| } |
| |
| /** |
| * Combines all the pages into a single unmodifiable iterable. ex. |
| * |
| * <pre> |
| * FluentIterable<StorageMetadata> blobs = blobstore.list(...).concat(); |
| * for (StorageMetadata blob : blobs) { |
| * process(blob); |
| * } |
| * </pre> |
| * |
| * @see Iterators#concat |
| */ |
| public FluentIterable<E> concat() { |
| final Iterator<FluentIterable<E>> iterator = iterator(); |
| final UnmodifiableIterator<Iterator<E>> unmodifiable = new UnmodifiableIterator<Iterator<E>>() { |
| @Override |
| public boolean hasNext() { |
| return iterator.hasNext(); |
| } |
| |
| @Override |
| public Iterator<E> next() { |
| return iterator.next().iterator(); |
| } |
| }; |
| return new FluentIterable<E>() { |
| @Override |
| public Iterator<E> iterator() { |
| return Iterators.concat(unmodifiable); |
| } |
| }; |
| } |
| |
| } |