Update #0 - First Release

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

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2008 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 java.io.IOException;
+import java.io.Reader;
+import java.util.Iterator;
+
+import javax.annotation.Nullable;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * A {@link Reader} that concatenates multiple readers.
+ *
+ * @author Bin Zhu
+ * @since 1.0
+ */
+class MultiReader extends Reader {
+	private final Iterator<? extends CharSource> it;
+	private Reader current;
+
+	MultiReader(Iterator<? extends CharSource> readers) throws IOException {
+		this.it = readers;
+		advance();
+	}
+
+	/**
+	 * Closes the current reader and opens the next one, if any.
+	 */
+	private void advance() throws IOException {
+		close();
+		if (it.hasNext()) {
+			current = it.next().openStream();
+		}
+	}
+
+	@Override
+	public int read(@Nullable char cbuf[], int off, int len) throws IOException {
+		if (current == null) {
+			return -1;
+		}
+		int result = current.read(cbuf, off, len);
+		if (result == -1) {
+			advance();
+			return read(cbuf, off, len);
+		}
+		return result;
+	}
+
+	@Override
+	public long skip(long n) throws IOException {
+		Preconditions.checkArgument(n >= 0, "n is negative");
+		if (n > 0) {
+			while (current != null) {
+				long result = current.skip(n);
+				if (result > 0) {
+					return result;
+				}
+				advance();
+			}
+		}
+		return 0;
+	}
+
+	@Override
+	public boolean ready() throws IOException {
+		return (current != null) && current.ready();
+	}
+
+	@Override
+	public void close() throws IOException {
+		if (current != null) {
+			try {
+				current.close();
+			} finally {
+				current = null;
+			}
+		}
+	}
+}