/*
 * Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

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 {@code line.separator}.
 * 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
 * @see java.nio.file.Files#newBufferedWriter
 *
 * @author Mark Reinhold
 * @since 1.1
 */

public class BufferedWriter extends Writer {

 private Writer out;

 private char cb[];
 private int nChars, nextChar;

 private static int defaultCharBufferSize = 8192;

 /**
 * 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 {@code sz <= 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;
 }

 /** 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}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
 *
 * @throws IndexOutOfBoundsException
 * If {@code off} is negative, or {@code len} is negative,
 * or {@code off + len} is negative or greater than the length
 * of the given array
 *
 * @throws 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.
 *
 * @implSpec
 * While the specification of this method in the
 * {@linkplain java.io.Writer#write(java.lang.String,int,int) superclass}
 * recommends that an {@link IndexOutOfBoundsException} be thrown
 * if {@code len} is negative or {@code off + len} is negative,
 * the implementation in this class does not throw such an exception in
 * these cases but instead simply writes no characters.
 *
 * @param s String to be written
 * @param off Offset from which to start reading characters
 * @param len Number of characters to be written
 *
 * @throws IndexOutOfBoundsException
 * If {@code off} is negative,
 * or {@code off + len} is greater than the length
 * of the given string
 *
 * @throws 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 {@code line.separator}, and is not necessarily a single
 * newline ('\n') character.
 *
 * @exception IOException If an I/O error occurs
 */
 public void newLine() throws IOException {
 write(System.lineSeparator());
 }

 /**
 * Flushes the stream.
 *
 * @exception IOException If an I/O error occurs
 */
 public void flush() throws IOException {
 synchronized (lock) {
 flushBuffer();
 out.flush();
 }
 }

 @SuppressWarnings("try")
 public void close() throws IOException {
 synchronized (lock) {
 if (out == null) {
 return;
 }
 try (Writer w = out) {
 flushBuffer();
 } finally {
 out = null;
 cb = null;
 }
 }
 }
}