1/*
2 * Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.io;
27
28import java.util.Arrays;
29
30/**
31 * This class implements a character buffer that can be used as an Writer.
32 * The buffer automatically grows when data is written to the stream.  The data
33 * can be retrieved using toCharArray() and toString().
34 * <P>
35 * Note: Invoking close() on this class has no effect, and methods
36 * of this class can be called after the stream has closed
37 * without generating an IOException.
38 *
39 * @author      Herb Jellinek
40 * @since       1.1
41 */
42public
43class CharArrayWriter extends Writer {
44    /**
45     * The buffer where data is stored.
46     */
47    protected char buf[];
48
49    /**
50     * The number of chars in the buffer.
51     */
52    protected int count;
53
54    /**
55     * Creates a new CharArrayWriter.
56     */
57    public CharArrayWriter() {
58        this(32);
59    }
60
61    /**
62     * Creates a new CharArrayWriter with the specified initial size.
63     *
64     * @param initialSize  an int specifying the initial buffer size.
65     * @exception IllegalArgumentException if initialSize is negative
66     */
67    public CharArrayWriter(int initialSize) {
68        if (initialSize < 0) {
69            throw new IllegalArgumentException("Negative initial size: "
70                                               + initialSize);
71        }
72        buf = new char[initialSize];
73    }
74
75    /**
76     * Writes a character to the buffer.
77     */
78    public void write(int c) {
79        synchronized (lock) {
80            int newcount = count + 1;
81            if (newcount > buf.length) {
82                buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
83            }
84            buf[count] = (char)c;
85            count = newcount;
86        }
87    }
88
89    /**
90     * Writes characters to the buffer.
91     * @param c the data to be written
92     * @param off       the start offset in the data
93     * @param len       the number of chars that are written
94     *
95     * @throws  IndexOutOfBoundsException
96     *          If {@code off} is negative, or {@code len} is negative,
97     *          or {@code off + len} is negative or greater than the length
98     *          of the given array
99     */
100    public void write(char c[], int off, int len) {
101        if ((off < 0) || (off > c.length) || (len < 0) ||
102            ((off + len) > c.length) || ((off + len) < 0)) {
103            throw new IndexOutOfBoundsException();
104        } else if (len == 0) {
105            return;
106        }
107        synchronized (lock) {
108            int newcount = count + len;
109            if (newcount > buf.length) {
110                buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
111            }
112            System.arraycopy(c, off, buf, count, len);
113            count = newcount;
114        }
115    }
116
117    /**
118     * Write a portion of a string to the buffer.
119     * @param  str  String to be written from
120     * @param  off  Offset from which to start reading characters
121     * @param  len  Number of characters to be written
122     *
123     * @throws  IndexOutOfBoundsException
124     *          If {@code off} is negative, or {@code len} is negative,
125     *          or {@code off + len} is negative or greater than the length
126     *          of the given string
127     */
128    public void write(String str, int off, int len) {
129        synchronized (lock) {
130            int newcount = count + len;
131            if (newcount > buf.length) {
132                buf = Arrays.copyOf(buf, Math.max(buf.length << 1, newcount));
133            }
134            str.getChars(off, off + len, buf, count);
135            count = newcount;
136        }
137    }
138
139    /**
140     * Writes the contents of the buffer to another character stream.
141     *
142     * @param out       the output stream to write to
143     * @throws IOException If an I/O error occurs.
144     */
145    public void writeTo(Writer out) throws IOException {
146        synchronized (lock) {
147            out.write(buf, 0, count);
148        }
149    }
150
151    /**
152     * Appends the specified character sequence to this writer.
153     *
154     * <p> An invocation of this method of the form {@code out.append(csq)}
155     * behaves in exactly the same way as the invocation
156     *
157     * <pre>
158     *     out.write(csq.toString()) </pre>
159     *
160     * <p> Depending on the specification of {@code toString} for the
161     * character sequence {@code csq}, the entire sequence may not be
162     * appended. For instance, invoking the {@code toString} method of a
163     * character buffer will return a subsequence whose content depends upon
164     * the buffer's position and limit.
165     *
166     * @param  csq
167     *         The character sequence to append.  If {@code csq} is
168     *         {@code null}, then the four characters {@code "null"} are
169     *         appended to this writer.
170     *
171     * @return  This writer
172     *
173     * @since  1.5
174     */
175    public CharArrayWriter append(CharSequence csq) {
176        String s = String.valueOf(csq);
177        write(s, 0, s.length());
178        return this;
179    }
180
181    /**
182     * Appends a subsequence of the specified character sequence to this writer.
183     *
184     * <p> An invocation of this method of the form
185     * {@code out.append(csq, start, end)} when
186     * {@code csq} is not {@code null}, behaves in
187     * exactly the same way as the invocation
188     *
189     * <pre>
190     *     out.write(csq.subSequence(start, end).toString()) </pre>
191     *
192     * @param  csq
193     *         The character sequence from which a subsequence will be
194     *         appended.  If {@code csq} is {@code null}, then characters
195     *         will be appended as if {@code csq} contained the four
196     *         characters {@code "null"}.
197     *
198     * @param  start
199     *         The index of the first character in the subsequence
200     *
201     * @param  end
202     *         The index of the character following the last character in the
203     *         subsequence
204     *
205     * @return  This writer
206     *
207     * @throws  IndexOutOfBoundsException
208     *          If {@code start} or {@code end} are negative, {@code start}
209     *          is greater than {@code end}, or {@code end} is greater than
210     *          {@code csq.length()}
211     *
212     * @since  1.5
213     */
214    public CharArrayWriter append(CharSequence csq, int start, int end) {
215        if (csq == null) csq = "null";
216        return append(csq.subSequence(start, end));
217    }
218
219    /**
220     * Appends the specified character to this writer.
221     *
222     * <p> An invocation of this method of the form {@code out.append(c)}
223     * behaves in exactly the same way as the invocation
224     *
225     * <pre>
226     *     out.write(c) </pre>
227     *
228     * @param  c
229     *         The 16-bit character to append
230     *
231     * @return  This writer
232     *
233     * @since 1.5
234     */
235    public CharArrayWriter append(char c) {
236        write(c);
237        return this;
238    }
239
240    /**
241     * Resets the buffer so that you can use it again without
242     * throwing away the already allocated buffer.
243     */
244    public void reset() {
245        count = 0;
246    }
247
248    /**
249     * Returns a copy of the input data.
250     *
251     * @return an array of chars copied from the input data.
252     */
253    public char[] toCharArray() {
254        synchronized (lock) {
255            return Arrays.copyOf(buf, count);
256        }
257    }
258
259    /**
260     * Returns the current size of the buffer.
261     *
262     * @return an int representing the current size of the buffer.
263     */
264    public int size() {
265        return count;
266    }
267
268    /**
269     * Converts input data to a string.
270     * @return the string.
271     */
272    public String toString() {
273        synchronized (lock) {
274            return new String(buf, 0, count);
275        }
276    }
277
278    /**
279     * Flush the stream.
280     */
281    public void flush() { }
282
283    /**
284     * Close the stream.  This method does not release the buffer, since its
285     * contents might still be required. Note: Invoking this method in this class
286     * will have no effect.
287     */
288    public void close() { }
289
290}
291