/*
 * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

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 static final int WRITE_BUFFER_SIZE = 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[WRITE_BUFFER_SIZE];
 }
 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 <= WRITE_BUFFER_SIZE) {
 if (writeBuffer == null) {
 writeBuffer = new char[WRITE_BUFFER_SIZE];
 }
 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;

}