/*

 * 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;

/**

 * Writes text to a character-output stream, buffering characters so as to

 * provide for the efficient writing of single characters, arrays, and strings.

 *

 * <p> The buffer size may be specified, or the default size may be accepted.

 * The default is large enough for most purposes.

 *

 * <p> A newLine() method is provided, which uses the platform's own notion of

 * line separator as defined by the system property <tt>line.separator</tt>.

 * Not all platforms use the newline character ('\n') to terminate lines.

 * Calling this method to terminate each output line is therefore preferred to

 * writing a newline character directly.

 *

 * <p> In general, a Writer sends its output immediately to the underlying

 * character or byte stream.  Unless prompt output is required, it is advisable

 * to wrap a BufferedWriter around any Writer whose write() operations may be

 * costly, such as FileWriters and OutputStreamWriters.  For example,

 *

 * <pre>

 * PrintWriter out

 *   = new PrintWriter(new BufferedWriter(new FileWriter("foo.out")));

 * </pre>

 *

 * will buffer the PrintWriter's output to the file.  Without buffering, each

 * invocation of a print() method would cause characters to be converted into

 * bytes that would then be written immediately to the file, which can be very

 * inefficient.

 *

 * @see PrintWriter

 * @see FileWriter

 * @see OutputStreamWriter

 *

 * @author      Mark Reinhold

 * @since       JDK1.1

 */

public class BufferedWriter extends Writer {

    private Writer out;

    private char cb[];

    private int nChars, nextChar;

    private static int defaultCharBufferSize = 8192;

    /**

     * Line separator string.  This is the value of the line.separator

     * property at the moment that the stream was created.

     */

    private String lineSeparator;

    /**

     * Creates a buffered character-output stream that uses a default-sized

     * output buffer.

     *

     * @param  out  A Writer

     */

    public BufferedWriter(Writer out) {

        this(out, defaultCharBufferSize);

    }

    /**

     * Creates a new buffered character-output stream that uses an output

     * buffer of the given size.

     *

     * @param  out  A Writer

     * @param  sz   Output-buffer size, a positive integer

     *

     * @exception  IllegalArgumentException  If sz is <= 0

     */

    public BufferedWriter(Writer out, int sz) {

        super(out);

        if (sz <= 0)

            throw new IllegalArgumentException("Buffer size <= 0");

        this.out = out;

        cb = new char[sz];

        nChars = sz;

        nextChar = 0;

        lineSeparator = java.security.AccessController.doPrivileged(

            new sun.security.action.GetPropertyAction("line.separator"));

    }

    /** Checks to make sure that the stream has not been closed */

    private void ensureOpen() throws IOException {

        if (out == null)

            throw new IOException("Stream closed");

    }

    /**

     * Flushes the output buffer to the underlying character stream, without

     * flushing the stream itself.  This method is non-private only so that it

     * may be invoked by PrintStream.

     */

    void flushBuffer() throws IOException {

        synchronized (lock) {

            ensureOpen();

            if (nextChar == 0)

                return;

            out.write(cb, 0, nextChar);

            nextChar = 0;

        }

    }

    /**

     * Writes a single character.

     *

     * @exception  IOException  If an I/O error occurs

     */

    public void write(int c) throws IOException {

        synchronized (lock) {

            ensureOpen();

            if (nextChar >= nChars)

                flushBuffer();

            cb[nextChar++] = (char) c;

        }

    }

    /**

     * Our own little min method, to avoid loading java.lang.Math if we've run

     * out of file descriptors and we're trying to print a stack trace.

     */

    private int min(int a, int b) {

        if (a < b) return a;

        return b;

    }

    /**

     * Writes a portion of an array of characters.

     *

     * <p> Ordinarily this method stores characters from the given array into

     * this stream's buffer, flushing the buffer to the underlying stream as

     * needed.  If the requested length is at least as large as the buffer,

     * however, then this method will flush the buffer and write the characters

     * directly to the underlying stream.  Thus redundant

     * <code>BufferedWriter</code>s will not copy data unnecessarily.

     *

     * @param  cbuf  A character array

     * @param  off   Offset from which to start reading characters

     * @param  len   Number of characters to write

     *

     * @exception  IOException  If an I/O error occurs

     */

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

        synchronized (lock) {

            ensureOpen();

            if ((off < 0) || (off > cbuf.length) || (len < 0) ||

                ((off + len) > cbuf.length) || ((off + len) < 0)) {

                throw new IndexOutOfBoundsException();

            } else if (len == 0) {

                return;

            }

            if (len >= nChars) {

                /* If the request length exceeds the size of the output buffer,

                   flush the buffer and then write the data directly.  In this

                   way buffered streams will cascade harmlessly. */

                flushBuffer();

                out.write(cbuf, off, len);

                return;

            }

            int b = off, t = off + len;

            while (b < t) {

                int d = min(nChars - nextChar, t - b);

                System.arraycopy(cbuf, b, cb, nextChar, d);

                b += d;

                nextChar += d;

                if (nextChar >= nChars)

                    flushBuffer();

            }

        }

    }

    /**

     * Writes a portion of a String.

     *

     * <p> If the value of the <tt>len</tt> parameter is negative then no

     * characters are written.  This is contrary to the specification of this

     * method in the {@linkplain java.io.Writer#write(java.lang.String,int,int)

     * superclass}, which requires that an {@link IndexOutOfBoundsException} be

     * thrown.

     *

     * @param  s     String to be written

     * @param  off   Offset from which to start reading characters

     * @param  len   Number of characters to be written

     *

     * @exception  IOException  If an I/O error occurs

     */

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

        synchronized (lock) {

            ensureOpen();

            int b = off, t = off + len;

            while (b < t) {

                int d = min(nChars - nextChar, t - b);

                s.getChars(b, b + d, cb, nextChar);

                b += d;

                nextChar += d;

                if (nextChar >= nChars)

                    flushBuffer();

            }

        }

    }

    /**

     * Writes a line separator.  The line separator string is defined by the

     * system property <tt>line.separator</tt>, and is not necessarily a single

     * newline ('\n') character.

     *

     * @exception  IOException  If an I/O error occurs

     */

    public void newLine() throws IOException {

        write(lineSeparator);

    }

    /**

     * Flushes the stream.

     *

     * @exception  IOException  If an I/O error occurs

     */

    public void flush() throws IOException {

        synchronized (lock) {

            flushBuffer();

            out.flush();

        }

    }

    public void close() throws IOException {

        synchronized (lock) {

            if (out == null) {

                return;

            }

            try {

                flushBuffer();

            } finally {

                out.close();

                out = null;

                cb = null;

            }

        }

    }

}