Update #0 - First Release

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

@@ -0,0 +1,128 @@
+/*
+ * Copyright (C) 2006 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.Closeable;
+import java.io.Flushable;
+import java.io.IOException;
+import java.io.Writer;
+
+import javax.annotation.Nullable;
+
+/**
+ * Writer that places all output on an {@link Appendable} target. If the target
+ * is {@link Flushable} or {@link Closeable}, flush()es and close()s will also
+ * be delegated to the target.
+ *
+ * @author Alan Green
+ * @author Sebastian Kanthak
+ * @since 1.0
+ */
+class AppendableWriter extends Writer {
+	private final Appendable target;
+	private boolean closed;
+
+	/**
+	 * Creates a new writer that appends everything it writes to {@code target}.
+	 *
+	 * @param target target to which to append output
+	 */
+	AppendableWriter(Appendable target) {
+		this.target = checkNotNull(target);
+	}
+
+	/*
+	 * Abstract methods from Writer
+	 */
+
+	@Override
+	public void write(char cbuf[], int off, int len) throws IOException {
+		checkNotClosed();
+		// It turns out that creating a new String is usually as fast, or faster
+		// than wrapping cbuf in a light-weight CharSequence.
+		target.append(new String(cbuf, off, len));
+	}
+
+	@Override
+	public void flush() throws IOException {
+		checkNotClosed();
+		if (target instanceof Flushable) {
+			((Flushable) target).flush();
+		}
+	}
+
+	@Override
+	public void close() throws IOException {
+		this.closed = true;
+		if (target instanceof Closeable) {
+			((Closeable) target).close();
+		}
+	}
+
+	/*
+	 * Override a few functions for performance reasons to avoid creating
+	 * unnecessary strings.
+	 */
+
+	@Override
+	public void write(int c) throws IOException {
+		checkNotClosed();
+		target.append((char) c);
+	}
+
+	@Override
+	public void write(@Nullable String str) throws IOException {
+		checkNotClosed();
+		target.append(str);
+	}
+
+	@Override
+	public void write(@Nullable String str, int off, int len) throws IOException {
+		checkNotClosed();
+		// tricky: append takes start, end pair...
+		target.append(str, off, off + len);
+	}
+
+	@Override
+	public Writer append(char c) throws IOException {
+		checkNotClosed();
+		target.append(c);
+		return this;
+	}
+
+	@Override
+	public Writer append(@Nullable CharSequence charSeq) throws IOException {
+		checkNotClosed();
+		target.append(charSeq);
+		return this;
+	}
+
+	@Override
+	public Writer append(@Nullable CharSequence charSeq, int start, int end) throws IOException {
+		checkNotClosed();
+		target.append(charSeq, start, end);
+		return this;
+	}
+
+	private void checkNotClosed() throws IOException {
+		if (closed) {
+			throw new IOException("Cannot write to a closed writer.");
+		}
+	}
+}