/*

  * 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.commons.flatfile.util;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.Arrays;

 import java.util.Iterator;

 import org.apache.commons.lang3.Validate;

 /**

  * Unified InputStream representation of multiple concatenated InputStreams.

  * @version $Revision: 1301242 $ $Date: 2012-03-15 17:14:40 -0500 (Thu, 15 Mar 2012) $

  */

 public class ConcatenatedInputStream extends InputStream {

     /** EOF */

     public static final int EOF = -1;

     private static final InputStream AT_EOF = new InputStream() {

         public int read() throws IOException {

             return EOF;

         }

     };

     private final Iterator<InputStream> iter;

     private InputStream current;

     /**

      * Create a new ConcatenatedInputStream.

      * @param src InputStreams

      */

     public ConcatenatedInputStream(Iterable<InputStream> src) {

         this.iter = Validate.notNull(src).iterator();

         next();

     }

     /**

      * Create a new ConcatenatedInputStream.

      * @param src InputStreams

      */

     public ConcatenatedInputStream(InputStream... src) {

         this(Arrays.asList(Validate.notNull(src)));

     }

     /**

      * {@inheritDoc}

      */

     public int read() throws IOException {

         int n = current.read();

         while (n == EOF && current != AT_EOF) {

             next();

             n = current.read();

         }

         return n;

     }

     /**

      * Position to the next InputStream

      */

     private void next() {

         current = iter.hasNext() ? iter.next() : AT_EOF;

     }

 }