/
AppendableWriter.java
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/
AppendableWriter.java
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/*
* 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 com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import java.io.Closeable;
import java.io.Flushable;
import java.io.IOException;
import java.io.Writer;
import javax.annotation.CheckForNull;
/**
* 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
*/
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
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 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(String str) throws IOException {
checkNotNull(str);
checkNotClosed();
target.append(str);
}
@Override
public void write(String str, int off, int len) throws IOException {
checkNotNull(str);
checkNotClosed();
// tricky: append takes start, end pair...
target.append(str, off, 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
public Writer append(char c) throws IOException {
checkNotClosed();
target.append(c);
return this;
}
@Override
public Writer append(@CheckForNull CharSequence charSeq) throws IOException {
checkNotClosed();
target.append(charSeq);
return this;
}
@Override
public Writer append(@CheckForNull 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.");
}
}
}