Update #0 - First Release

sources/main/java/com/google/common/io/MultiInputStream.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2007 The Guava Authors
+ *
+ * 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 com.google.common.io;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Iterator;
+
+import javax.annotation.Nullable;
+
+/**
+ * An {@link InputStream} that concatenates multiple substreams. At most one
+ * stream will be open at a time.
+ *
+ * @author Chris Nokleberg
+ * @since 1.0
+ */
+final class MultiInputStream extends InputStream {
+
+	private Iterator<? extends ByteSource> it;
+	private InputStream in;
+
+	/**
+	 * Creates a new instance.
+	 *
+	 * @param it an iterator of I/O suppliers that will provide each substream
+	 */
+	public MultiInputStream(Iterator<? extends ByteSource> it) throws IOException {
+		this.it = checkNotNull(it);
+		advance();
+	}
+
+	@Override
+	public void close() throws IOException {
+		if (in != null) {
+			try {
+				in.close();
+			} finally {
+				in = null;
+			}
+		}
+	}
+
+	/**
+	 * Closes the current input stream and opens the next one, if any.
+	 */
+	private void advance() throws IOException {
+		close();
+		if (it.hasNext()) {
+			in = it.next().openStream();
+		}
+	}
+
+	@Override
+	public int available() throws IOException {
+		if (in == null) {
+			return 0;
+		}
+		return in.available();
+	}
+
+	@Override
+	public boolean markSupported() {
+		return false;
+	}
+
+	@Override
+	public int read() throws IOException {
+		if (in == null) {
+			return -1;
+		}
+		int result = in.read();
+		if (result == -1) {
+			advance();
+			return read();
+		}
+		return result;
+	}
+
+	@Override
+	public int read(@Nullable byte[] b, int off, int len) throws IOException {
+		if (in == null) {
+			return -1;
+		}
+		int result = in.read(b, off, len);
+		if (result == -1) {
+			advance();
+			return read(b, off, len);
+		}
+		return result;
+	}
+
+	@Override
+	public long skip(long n) throws IOException {
+		if (in == null || n <= 0) {
+			return 0;
+		}
+		long result = in.skip(n);
+		if (result != 0) {
+			return result;
+		}
+		if (read() == -1) {
+			return 0;
+		}
+		return 1 + in.skip(n - 1);
+	}
+}