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 *
034 * @param <T> The type of the {@link Appendable} wrapped by this AppendableWriter.
035 */
036public class AppendableWriter <T extends Appendable> extends Writer {
037
038    private final T appendable;
039
040    /**
041     * Constructs a new instance with the specified appendable.
042     *
043     * @param appendable the appendable to write to
044     */
045    public AppendableWriter(final T appendable) {
046        this.appendable = appendable;
047    }
048
049    /**
050     * Appends the specified character to the underlying appendable.
051     *
052     * @param c the character to append
053     * @return this writer
054     * @throws IOException upon error
055     */
056    @Override
057    public Writer append(final char c) throws IOException {
058        appendable.append(c);
059        return this;
060    }
061
062    /**
063     * Appends the specified character sequence to the underlying appendable.
064     *
065     * @param csq the character sequence to append
066     * @return this writer
067     * @throws IOException upon error
068     */
069    @Override
070    public Writer append(final CharSequence csq) throws IOException {
071        appendable.append(csq);
072        return this;
073    }
074
075    /**
076     * Appends a subsequence of the specified character sequence to the underlying appendable.
077     *
078     * @param csq the character sequence from which a subsequence will be appended
079     * @param start the index of the first character in the subsequence
080     * @param end the index of the character following the last character in the subsequence
081     * @return this writer
082     * @throws IOException upon error
083     */
084    @Override
085    public Writer append(final CharSequence csq, final int start, final int end) throws IOException {
086        appendable.append(csq, start, end);
087        return this;
088    }
089
090    /**
091     * Closes the stream. This implementation does nothing.
092     *
093     * @throws IOException upon error
094     */
095    @Override
096    public void close() throws IOException {
097        // noop
098    }
099
100    /**
101     * Flushes the stream. This implementation does nothing.
102     *
103     * @throws IOException upon error
104     */
105    @Override
106    public void flush() throws IOException {
107        // noop
108    }
109
110    /**
111     * Gets the target appendable.
112     *
113     * @return the target appendable
114     */
115    public T getAppendable() {
116        return appendable;
117    }
118
119    /**
120     * Writes a portion of an array of characters to the underlying appendable.
121     *
122     * @param cbuf an array with the characters to write
123     * @param off offset from which to start writing characters
124     * @param len number of characters to write
125     * @throws IOException upon error
126     */
127    @Override
128    public void write(final char[] cbuf, final int off, final int len) throws IOException {
129        Objects.requireNonNull(cbuf, "cbuf");
130        if (len < 0 || off + len > cbuf.length) {
131            throw new IndexOutOfBoundsException("Array Size=" + cbuf.length +
132                    ", offset=" + off + ", length=" + len);
133        }
134        for (int i = 0; i < len; i++) {
135            appendable.append(cbuf[off + i]);
136        }
137    }
138
139    /**
140     * Writes a character to the underlying appendable.
141     *
142     * @param c the character to write
143     * @throws IOException upon error
144     */
145    @Override
146    public void write(final int c) throws IOException {
147        appendable.append((char) c);
148    }
149
150    /**
151     * Writes a portion of a String to the underlying appendable.
152     *
153     * @param str a string
154     * @param off offset from which to start writing characters
155     * @param len number of characters to write
156     * @throws IOException upon error
157     */
158    @Override
159    public void write(final String str, final int off, final int len) throws IOException {
160        // appendable.append will add "null" for a null String; add an explicit null check
161        Objects.requireNonNull(str, "str");
162        appendable.append(str, off, off + len);
163    }
164
165}