001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.output;
018
019import java.io.IOException;
020import java.io.Writer;
021import java.util.Objects;
022
023/**
024 * Writer implementation that writes the data to an {@link Appendable}
025 * Object.
026 * <p>
027 * For example, can be used with a {@link StringBuilder}
028 * or {@link StringBuffer}.
029 * </p>
030 *
031 * @since 2.7
032 * @see Appendable
033 * @param <T> The type of the {@link Appendable} wrapped by this AppendableWriter.
034 */
035public class AppendableWriter <T extends Appendable> extends Writer {
036
037    private final T appendable;
038
039    /**
040     * Constructs a new instance with the specified appendable.
041     *
042     * @param appendable the appendable to write to
043     */
044    public AppendableWriter(final T appendable) {
045        this.appendable = appendable;
046    }
047
048    /**
049     * Appends the specified character to the underlying appendable.
050     *
051     * @param c the character to append
052     * @return this writer
053     * @throws IOException upon error
054     */
055    @Override
056    public Writer append(final char c) throws IOException {
057        appendable.append(c);
058        return this;
059    }
060
061    /**
062     * Appends the specified character sequence to the underlying appendable.
063     *
064     * @param csq the character sequence to append
065     * @return this writer
066     * @throws IOException upon error
067     */
068    @Override
069    public Writer append(final CharSequence csq) throws IOException {
070        appendable.append(csq);
071        return this;
072    }
073
074    /**
075     * Appends a subsequence of the specified character sequence to the underlying appendable.
076     *
077     * @param csq the character sequence from which a subsequence will be appended
078     * @param start the index of the first character in the subsequence
079     * @param end the index of the character following the last character in the subsequence
080     * @return this writer
081     * @throws IOException upon error
082     */
083    @Override
084    public Writer append(final CharSequence csq, final int start, final int end) throws IOException {
085        appendable.append(csq, start, end);
086        return this;
087    }
088
089    /**
090     * Closes the stream. This implementation does nothing.
091     *
092     * @throws IOException upon error
093     */
094    @Override
095    public void close() throws IOException {
096        // noop
097    }
098
099    /**
100     * Flushes the stream. This implementation does nothing.
101     *
102     * @throws IOException upon error
103     */
104    @Override
105    public void flush() throws IOException {
106        // noop
107    }
108
109    /**
110     * Gets the target appendable.
111     *
112     * @return the target appendable
113     */
114    public T getAppendable() {
115        return appendable;
116    }
117
118    /**
119     * Writes a portion of an array of characters to the underlying appendable.
120     *
121     * @param cbuf an array with the characters to write
122     * @param off offset from which to start writing characters
123     * @param len number of characters to write
124     * @throws IOException upon error
125     */
126    @Override
127    public void write(final char[] cbuf, final int off, final int len) throws IOException {
128        Objects.requireNonNull(cbuf, "cbuf");
129        if (len < 0 || off + len > cbuf.length) {
130            throw new IndexOutOfBoundsException("Array Size=" + cbuf.length +
131                    ", offset=" + off + ", length=" + len);
132        }
133        for (int i = 0; i < len; i++) {
134            appendable.append(cbuf[off + i]);
135        }
136    }
137
138    /**
139     * Writes a character to the underlying appendable.
140     *
141     * @param c the character to write
142     * @throws IOException upon error
143     */
144    @Override
145    public void write(final int c) throws IOException {
146        appendable.append((char) c);
147    }
148
149    /**
150     * Writes a portion of a String to the underlying appendable.
151     *
152     * @param str a string
153     * @param off offset from which to start writing characters
154     * @param len number of characters to write
155     * @throws IOException upon error
156     */
157    @Override
158    public void write(final String str, final int off, final int len) throws IOException {
159        // appendable.append will add "null" for a null String; add an explicit null check
160        Objects.requireNonNull(str, "str");
161        appendable.append(str, off, off + len);
162    }
163
164}