diff options
Diffstat (limited to 'sandbox/sebastien/java/embed/modules/common-java/src/main/java/org/apache/tuscany/sca/common/java/collection/CompoundIterator.java')
-rw-r--r-- | sandbox/sebastien/java/embed/modules/common-java/src/main/java/org/apache/tuscany/sca/common/java/collection/CompoundIterator.java | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/sandbox/sebastien/java/embed/modules/common-java/src/main/java/org/apache/tuscany/sca/common/java/collection/CompoundIterator.java b/sandbox/sebastien/java/embed/modules/common-java/src/main/java/org/apache/tuscany/sca/common/java/collection/CompoundIterator.java new file mode 100644 index 0000000000..997ba89881 --- /dev/null +++ b/sandbox/sebastien/java/embed/modules/common-java/src/main/java/org/apache/tuscany/sca/common/java/collection/CompoundIterator.java @@ -0,0 +1,113 @@ +/* + * 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.tuscany.sca.common.java.collection; + +import java.util.Collection; +import java.util.Iterator; +import java.util.NoSuchElementException; + +public class CompoundIterator<T> implements Iterator<T> { + private Iterator<T>[] iterators = null; + private int index = 0; + + public CompoundIterator(Iterator<T>... iterators) { + this.iterators = iterators; + } + + @SuppressWarnings("unchecked") + public CompoundIterator(Collection<T>... collections) { + this.iterators = new Iterator[collections.length]; + for (int i = 0; i < collections.length; i++) { + this.iterators[i] = collections[i].iterator(); + } + } + + public boolean hasNext() { + // if the current enum is null that means this enum is finished + if (currentIterator() == null) { + // No next enum + return false; + } + // If the current enum has more elements, lets go + return currentIterator().hasNext(); + } + + private Iterator<T> findNextIterator(boolean moveCursor) { + return findNextIterator(index, moveCursor); + } + + private Iterator<T> findNextIterator(int cursor, boolean moveCursor) { + // next place in the array + int next = cursor + 1; + // If the cursor is still in the array + if (next < iterators.length) { + + // If there is something in that place + // AND the enum is not empty + if (iterators[next] != null && iterators[next].hasNext()) { + // OK + if (moveCursor) { + index = next; + } + return iterators[next]; + } + // Try next element + return findNextIterator(next, moveCursor); + } + // No more elements available + return null; + } + + public T next() { + // ask for the next element of the current enum. + if (currentIterator() != null) { + return currentIterator().next(); + } + + // no more elements in this Enum + // We must throw a NoSuchElementException + throw new NoSuchElementException("No more elements"); + } + + public void remove() { + // ask for the next element of the current enum. + if (currentIterator() != null) { + currentIterator().remove(); + } + + // no more elements in this Enum + // We must throw a NoSuchElementException + throw new NoSuchElementException("No more elements"); + } + + private Iterator<T> currentIterator() { + if (iterators != null) { + if (index < iterators.length) { + Iterator<T> e = iterators[index]; + if (e == null || !e.hasNext()) { + // the current enum is null or empty + // we probably want to switch to the next one + e = findNextIterator(true); + } + return e; + } + } + return null; + } +} |