/*

 * Copyright 1996-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.io;

/**

 * Abstract class for writing to character streams.  The only methods that a

 * subclass must implement are write(char[], int, int), flush(), and close().

 * Most subclasses, however, will override some of the methods defined here in

 * order to provide higher efficiency, additional functionality, or both.

 *

 * @see Writer

 * @see   BufferedWriter

 * @see   CharArrayWriter

 * @see   FilterWriter

 * @see   OutputStreamWriter

 * @see     FileWriter

 * @see   PipedWriter

 * @see   PrintWriter

 * @see   StringWriter

 * @see Reader

 *

 * @author      Mark Reinhold

 * @since       JDK1.1

 */

public abstract class Writer implements Appendable, Closeable, Flushable {

    /**

     * Temporary buffer used to hold writes of strings and single characters

     */

    private char[] writeBuffer;

    /**

     * Size of writeBuffer, must be >= 1

     */

    private final int writeBufferSize = 1024;

    /**

     * The object used to synchronize operations on this stream.  For

     * efficiency, a character-stream object may use an object other than

     * itself to protect critical sections.  A subclass should therefore use

     * the object in this field rather than <tt>this</tt> or a synchronized

     * method.

     */

    protected Object lock;

    /**

     * Creates a new character-stream writer whose critical sections will

     * synchronize on the writer itself.

     */

    protected Writer() {

        this.lock = this;

    }

    /**

     * Creates a new character-stream writer whose critical sections will

     * synchronize on the given object.

     *

     * @param  lock

     *         Object to synchronize on

     */

    protected Writer(Object lock) {

        if (lock == null) {

            throw new NullPointerException();

        }

        this.lock = lock;

    }

    /**

     * Writes a single character.  The character to be written is contained in

     * the 16 low-order bits of the given integer value; the 16 high-order bits

     * are ignored.

     *

     * <p> Subclasses that intend to support efficient single-character output

     * should override this method.

     *

     * @param  c

     *         int specifying a character to be written

     *

     * @throws  IOException

     *          If an I/O error occurs

     */

    public void write(int c) throws IOException {

        synchronized (lock) {

            if (writeBuffer == null){

                writeBuffer = new char[writeBufferSize];

            }

            writeBuffer[0] = (char) c;

            write(writeBuffer, 0, 1);

        }

    }

    /**

     * Writes an array of characters.

     *

     * @param  cbuf

     *         Array of characters to be written

     *

     * @throws  IOException

     *          If an I/O error occurs

     */

    public void write(char cbuf[]) throws IOException {

        write(cbuf, 0, cbuf.length);

    }

    /**

     * Writes a portion of an array of characters.

     *

     * @param  cbuf

     *         Array of characters

     *

     * @param  off

     *         Offset from which to start writing characters

     *

     * @param  len

     *         Number of characters to write

     *

     * @throws  IOException

     *          If an I/O error occurs

     */

    abstract public void write(char cbuf[], int off, int len) throws IOException;

    /**

     * Writes a string.

     *

     * @param  str

     *         String to be written

     *

     * @throws  IOException

     *          If an I/O error occurs

     */

    public void write(String str) throws IOException {

        write(str, 0, str.length());

    }

    /**

     * Writes a portion of a string.

     *

     * @param  str

     *         A String

     *

     * @param  off

     *         Offset from which to start writing characters

     *

     * @param  len

     *         Number of characters to write

     *

     * @throws  IndexOutOfBoundsException

     *          If <tt>off</tt> is negative, or <tt>len</tt> is negative,

     *          or <tt>off+len</tt> is negative or greater than the length

     *          of the given string

     *

     * @throws  IOException

     *          If an I/O error occurs

     */

    public void write(String str, int off, int len) throws IOException {

        synchronized (lock) {

            char cbuf[];

            if (len <= writeBufferSize) {

                if (writeBuffer == null) {

                    writeBuffer = new char[writeBufferSize];

                }

                cbuf = writeBuffer;

            } else {    // Don't permanently allocate very large buffers.

                cbuf = new char[len];

            }

            str.getChars(off, (off + len), cbuf, 0);

            write(cbuf, 0, len);

        }

    }

    /**

     * Appends the specified character sequence to this writer.

     *

     * <p> An invocation of this method of the form <tt>out.append(csq)</tt>

     * behaves in exactly the same way as the invocation

     *

     * <pre>

     *     out.write(csq.toString()) </pre>

     *

     * <p> Depending on the specification of <tt>toString</tt> for the

     * character sequence <tt>csq</tt>, the entire sequence may not be

     * appended. For instance, invoking the <tt>toString</tt> method of a

     * character buffer will return a subsequence whose content depends upon

     * the buffer's position and limit.

     *

     * @param  csq

     *         The character sequence to append.  If <tt>csq</tt> is

     *         <tt>null</tt>, then the four characters <tt>"null"</tt> are

     *         appended to this writer.

     *

     * @return  This writer

     *

     * @throws  IOException

     *          If an I/O error occurs

     *

     * @since  1.5

     */

    public Writer append(CharSequence csq) throws IOException {

        if (csq == null)

            write("null");

        else

            write(csq.toString());

        return this;

    }

    /**

     * Appends a subsequence of the specified character sequence to this writer.

     * <tt>Appendable</tt>.

     *

     * <p> An invocation of this method of the form <tt>out.append(csq, start,

     * end)</tt> when <tt>csq</tt> is not <tt>null</tt> behaves in exactly the

     * same way as the invocation

     *

     * <pre>

     *     out.write(csq.subSequence(start, end).toString()) </pre>

     *

     * @param  csq

     *         The character sequence from which a subsequence will be

     *         appended.  If <tt>csq</tt> is <tt>null</tt>, then characters

     *         will be appended as if <tt>csq</tt> contained the four

     *         characters <tt>"null"</tt>.

     *

     * @param  start

     *         The index of the first character in the subsequence

     *

     * @param  end

     *         The index of the character following the last character in the

     *         subsequence

     *

     * @return  This writer

     *

     * @throws  IndexOutOfBoundsException

     *          If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>

     *          is greater than <tt>end</tt>, or <tt>end</tt> is greater than

     *          <tt>csq.length()</tt>

     *

     * @throws  IOException

     *          If an I/O error occurs

     *

     * @since  1.5

     */

    public Writer append(CharSequence csq, int start, int end) throws IOException {

        CharSequence cs = (csq == null ? "null" : csq);

        write(cs.subSequence(start, end).toString());

        return this;

    }

    /**

     * Appends the specified character to this writer.

     *

     * <p> An invocation of this method of the form <tt>out.append(c)</tt>

     * behaves in exactly the same way as the invocation

     *

     * <pre>

     *     out.write(c) </pre>

     *

     * @param  c

     *         The 16-bit character to append

     *

     * @return  This writer

     *

     * @throws  IOException

     *          If an I/O error occurs

     *

     * @since 1.5

     */

    public Writer append(char c) throws IOException {

        write(c);

        return this;

    }

    /**

     * Flushes the stream.  If the stream has saved any characters from the

     * various write() methods in a buffer, write them immediately to their

     * intended destination.  Then, if that destination is another character or

     * byte stream, flush it.  Thus one flush() invocation will flush all the

     * buffers in a chain of Writers and OutputStreams.

     *

     * <p> If the intended destination of this stream is an abstraction provided

     * by the underlying operating system, for example a file, then flushing the

     * stream guarantees only that bytes previously written to the stream are

     * passed to the operating system for writing; it does not guarantee that

     * they are actually written to a physical device such as a disk drive.

     *

     * @throws  IOException

     *          If an I/O error occurs

     */

    abstract public void flush() throws IOException;

    /**

     * Closes the stream, flushing it first. Once the stream has been closed,

     * further write() or flush() invocations will cause an IOException to be

     * thrown. Closing a previously closed stream has no effect.

     *

     * @throws  IOException

     *          If an I/O error occurs

     */

    abstract public void close() throws IOException;

}