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	/*
	* Copyright (c) 1996, 2021, Oracle and/or its affiliates. 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. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.io;


	import java.util.Iterator;
	import java.util.NoSuchElementException;
	import java.util.Objects;
	import java.util.Spliterator;
	import java.util.Spliterators;
	import java.util.stream.Stream;
	import java.util.stream.StreamSupport;

	/**
	* Reads text from a character-input stream, buffering characters so as to
	* provide for the efficient reading of characters, arrays, and lines.
	*
	* <p> The buffer size may be specified, or the default size may be used. The
	* default is large enough for most purposes.
	*
	* <p> In general, each read request made of a Reader causes a corresponding
	* read request to be made of the underlying character or byte stream. It is
	* therefore advisable to wrap a BufferedReader around any Reader whose read()
	* operations may be costly, such as FileReaders and InputStreamReaders. For
	* example,
	*
	* <pre>
	* BufferedReader in
	* = new BufferedReader(new FileReader("foo.in"));
	* </pre>
	*
	* will buffer the input from the specified file. Without buffering, each
	* invocation of read() or readLine() could cause bytes to be read from the
	* file, converted into characters, and then returned, which can be very
	* inefficient.
	*
	* <p> Programs that use DataInputStreams for textual input can be localized by
	* replacing each DataInputStream with an appropriate BufferedReader.
	*
	* @see FileReader
	* @see InputStreamReader
	* @see java.nio.file.Files#newBufferedReader
	*
	* @author Mark Reinhold
	* @since 1.1
	*/

	public class BufferedReader extends Reader {

	private Reader in;

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

	private static final int INVALIDATED = -2;
	private static final int UNMARKED = -1;
	private int markedChar = UNMARKED;
	private int readAheadLimit = 0; /* Valid only when markedChar > 0 */

	/** If the next character is a line feed, skip it */
	private boolean skipLF = false;

	/** The skipLF flag when the mark was set */
	private boolean markedSkipLF = false;

	private static int defaultCharBufferSize = 8192;
	private static int defaultExpectedLineLength = 80;

	/**
	* Creates a buffering character-input stream that uses an input buffer of
	* the specified size.
	*
	* @param in A Reader
	* @param sz Input-buffer size
	*
	* @throws IllegalArgumentException If {@code sz <= 0}
	*/
	public BufferedReader(Reader in, int sz) {
	super(in);
	if (sz <= 0)
	throw new IllegalArgumentException("Buffer size <= 0");
	this.in = in;
	cb = new char[sz];
	nextChar = nChars = 0;
	}

	/**
	* Creates a buffering character-input stream that uses a default-sized
	* input buffer.
	*
	* @param in A Reader
	*/
	public BufferedReader(Reader in) {
	this(in, defaultCharBufferSize);
	}

	/** Checks to make sure that the stream has not been closed */
	private void ensureOpen() throws IOException {
	if (in == null)
	throw new IOException("Stream closed");
	}

	/**
	* Fills the input buffer, taking the mark into account if it is valid.
	*/
	private void fill() throws IOException {
	int dst;
	if (markedChar <= UNMARKED) {
	/* No mark */
	dst = 0;
	} else {
	/* Marked */
	int delta = nextChar - markedChar;
	if (delta >= readAheadLimit) {
	/* Gone past read-ahead limit: Invalidate mark */
	markedChar = INVALIDATED;
	readAheadLimit = 0;
	dst = 0;
	} else {
	if (readAheadLimit <= cb.length) {
	/* Shuffle in the current buffer */
	System.arraycopy(cb, markedChar, cb, 0, delta);
	markedChar = 0;
	dst = delta;
	} else {
	/* Reallocate buffer to accommodate read-ahead limit */
	char[] ncb = new char[readAheadLimit];
	System.arraycopy(cb, markedChar, ncb, 0, delta);
	cb = ncb;
	markedChar = 0;
	dst = delta;
	}
	nextChar = nChars = delta;
	}
	}

	int n;
	do {
	n = in.read(cb, dst, cb.length - dst);
	} while (n == 0);
	if (n > 0) {
	nChars = dst + n;
	nextChar = dst;
	}
	}

	/**
	* Reads a single character.
	*
	* @return The character read, as an integer in the range
	* 0 to 65535 ({@code 0x00-0xffff}), or -1 if the
	* end of the stream has been reached
	* @throws IOException If an I/O error occurs
	*/
	public int read() throws IOException {
	synchronized (lock) {
	ensureOpen();
	for (;;) {
	if (nextChar >= nChars) {
	fill();
	if (nextChar >= nChars)
	return -1;
	}
	if (skipLF) {
	skipLF = false;
	if (cb[nextChar] == '\n') {
	nextChar++;
	continue;
	}
	}
	return cb[nextChar++];
	}
	}
	}

	/**
	* Reads characters into a portion of an array, reading from the underlying
	* stream if necessary.
	*/
	private int read1(char[] cbuf, int off, int len) throws IOException {
	if (nextChar >= nChars) {
	/* If the requested length is at least as large as the buffer, and
	if there is no mark/reset activity, and if line feeds are not
	being skipped, do not bother to copy the characters into the
	local buffer. In this way buffered streams will cascade
	harmlessly. */
	if (len >= cb.length && markedChar <= UNMARKED && !skipLF) {
	return in.read(cbuf, off, len);
	}
	fill();
	}
	if (nextChar >= nChars) return -1;
	if (skipLF) {
	skipLF = false;
	if (cb[nextChar] == '\n') {
	nextChar++;
	if (nextChar >= nChars)
	fill();
	if (nextChar >= nChars)
	return -1;
	}
	}
	int n = Math.min(len, nChars - nextChar);
	System.arraycopy(cb, nextChar, cbuf, off, n);
	nextChar += n;
	return n;
	}

	/**
	* Reads characters into a portion of an array.
	*
	* <p> This method implements the general contract of the corresponding
	* {@link Reader#read(char[], int, int) read} method of the
	* {@link Reader} class. As an additional convenience, it
	* attempts to read as many characters as possible by repeatedly invoking
	* the {@code read} method of the underlying stream. This iterated
	* {@code read} continues until one of the following conditions becomes
	* true:
	* <ul>
	*
	* <li> The specified number of characters have been read,
	*
	* <li> The {@code read} method of the underlying stream returns
	* {@code -1}, indicating end-of-file, or
	*
	* <li> The {@code ready} method of the underlying stream
	* returns {@code false}, indicating that further input requests
	* would block.
	*
	* </ul>
	* If the first {@code read} on the underlying stream returns
	* {@code -1} to indicate end-of-file then this method returns
	* {@code -1}. Otherwise this method returns the number of characters
	* actually read.
	*
	* <p> Subclasses of this class are encouraged, but not required, to
	* attempt to read as many characters as possible in the same fashion.
	*
	* <p> Ordinarily this method takes characters from this stream's character
	* buffer, filling it from the underlying stream as necessary. If,
	* however, the buffer is empty, the mark is not valid, and the requested
	* length is at least as large as the buffer, then this method will read
	* characters directly from the underlying stream into the given array.
	* Thus redundant {@code BufferedReader}s will not copy data
	* unnecessarily.
	*
	* @param cbuf {@inheritDoc}
	* @param off {@inheritDoc}
	* @param len {@inheritDoc}
	*
	* @return {@inheritDoc}
	*
	* @throws IndexOutOfBoundsException {@inheritDoc}
	* @throws IOException {@inheritDoc}
	*/
	public int read(char[] cbuf, int off, int len) throws IOException {
	synchronized (lock) {
	ensureOpen();
	Objects.checkFromIndexSize(off, len, cbuf.length);
	if (len == 0) {
	return 0;
	}

	int n = read1(cbuf, off, len);
	if (n <= 0) return n;
	while ((n < len) && in.ready()) {
	int n1 = read1(cbuf, off + n, len - n);
	if (n1 <= 0) break;
	n += n1;
	}
	return n;
	}
	}

	/**
	* Reads a line of text. A line is considered to be terminated by any one
	* of a line feed ('\n'), a carriage return ('\r'), a carriage return
	* followed immediately by a line feed, or by reaching the end-of-file
	* (EOF).
	*
	* @param ignoreLF If true, the next '\n' will be skipped
	* @param term Output: Whether a line terminator was encountered
	* while reading the line; may be {@code null}.
	*
	* @return A String containing the contents of the line, not including
	* any line-termination characters, or null if the end of the
	* stream has been reached without reading any characters
	*
	* @see java.io.LineNumberReader#readLine()
	*
	* @throws IOException If an I/O error occurs
	*/
	String readLine(boolean ignoreLF, boolean[] term) throws IOException {
	StringBuilder s = null;
	int startChar;

	synchronized (lock) {
	ensureOpen();
	boolean omitLF = ignoreLF \|\| skipLF;
	if (term != null) term[0] = false;

	bufferLoop:
	for (;;) {

	if (nextChar >= nChars)
	fill();
	if (nextChar >= nChars) { /* EOF */
	if (s != null && s.length() > 0)
	return s.toString();
	else
	return null;
	}
	boolean eol = false;
	char c = 0;
	int i;

	/* Skip a leftover '\n', if necessary */
	if (omitLF && (cb[nextChar] == '\n'))
	nextChar++;
	skipLF = false;
	omitLF = false;

	charLoop:
	for (i = nextChar; i < nChars; i++) {
	c = cb[i];
	if ((c == '\n') \|\| (c == '\r')) {
	if (term != null) term[0] = true;
	eol = true;
	break charLoop;
	}
	}

	startChar = nextChar;
	nextChar = i;

	if (eol) {
	String str;
	if (s == null) {
	str = new String(cb, startChar, i - startChar);
	} else {
	s.append(cb, startChar, i - startChar);
	str = s.toString();
	}
	nextChar++;
	if (c == '\r') {
	skipLF = true;
	}
	return str;
	}

	if (s == null)
	s = new StringBuilder(defaultExpectedLineLength);
	s.append(cb, startChar, i - startChar);
	}
	}
	}

	/**
	* Reads a line of text. A line is considered to be terminated by any one
	* of a line feed ('\n'), a carriage return ('\r'), a carriage return
	* followed immediately by a line feed, or by reaching the end-of-file
	* (EOF).
	*
	* @return A String containing the contents of the line, not including
	* any line-termination characters, or null if the end of the
	* stream has been reached without reading any characters
	*
	* @throws IOException If an I/O error occurs
	*
	* @see java.nio.file.Files#readAllLines
	*/
	public String readLine() throws IOException {
	return readLine(false, null);
	}

	/**
	* {@inheritDoc}
	*/
	public long skip(long n) throws IOException {
	if (n < 0L) {
	throw new IllegalArgumentException("skip value is negative");
	}
	synchronized (lock) {
	ensureOpen();
	long r = n;
	while (r > 0) {
	if (nextChar >= nChars)
	fill();
	if (nextChar >= nChars) /* EOF */
	break;
	if (skipLF) {
	skipLF = false;
	if (cb[nextChar] == '\n') {
	nextChar++;
	}
	}
	long d = nChars - nextChar;
	if (r <= d) {
	nextChar += r;
	r = 0;
	break;
	}
	else {
	r -= d;
	nextChar = nChars;
	}
	}
	return n - r;
	}
	}

	/**
	* Tells whether this stream is ready to be read. A buffered character
	* stream is ready if the buffer is not empty, or if the underlying
	* character stream is ready.
	*
	* @throws IOException If an I/O error occurs
	*/
	public boolean ready() throws IOException {
	synchronized (lock) {
	ensureOpen();

	/*
	* If newline needs to be skipped and the next char to be read
	* is a newline character, then just skip it right away.
	*/
	if (skipLF) {
	/* Note that in.ready() will return true if and only if the next
	* read on the stream will not block.
	*/
	if (nextChar >= nChars && in.ready()) {
	fill();
	}
	if (nextChar < nChars) {
	if (cb[nextChar] == '\n')
	nextChar++;
	skipLF = false;
	}
	}
	return (nextChar < nChars) \|\| in.ready();
	}
	}

	/**
	* Tells whether this stream supports the mark() operation, which it does.
	*/
	public boolean markSupported() {
	return true;
	}

	/**
	* Marks the present position in the stream. Subsequent calls to reset()
	* will attempt to reposition the stream to this point.
	*
	* @param readAheadLimit Limit on the number of characters that may be
	* read while still preserving the mark. An attempt
	* to reset the stream after reading characters
	* up to this limit or beyond may fail.
	* A limit value larger than the size of the input
	* buffer will cause a new buffer to be allocated
	* whose size is no smaller than limit.
	* Therefore large values should be used with care.
	*
	* @throws IllegalArgumentException If {@code readAheadLimit < 0}
	* @throws IOException If an I/O error occurs
	*/
	public void mark(int readAheadLimit) throws IOException {
	if (readAheadLimit < 0) {
	throw new IllegalArgumentException("Read-ahead limit < 0");
	}
	synchronized (lock) {
	ensureOpen();
	this.readAheadLimit = readAheadLimit;
	markedChar = nextChar;
	markedSkipLF = skipLF;
	}
	}

	/**
	* Resets the stream to the most recent mark.
	*
	* @throws IOException If the stream has never been marked,
	* or if the mark has been invalidated
	*/
	public void reset() throws IOException {
	synchronized (lock) {
	ensureOpen();
	if (markedChar < 0)
	throw new IOException((markedChar == INVALIDATED)
	? "Mark invalid"
	: "Stream not marked");
	nextChar = markedChar;
	skipLF = markedSkipLF;
	}
	}

	public void close() throws IOException {
	synchronized (lock) {
	if (in == null)
	return;
	try {
	in.close();
	} finally {
	in = null;
	cb = null;
	}
	}
	}

	/**
	* Returns a {@code Stream}, the elements of which are lines read from
	* this {@code BufferedReader}. The {@link Stream} is lazily populated,
	* i.e., read only occurs during the
	* <a href="../util/stream/package-summary.html#StreamOps">terminal
	* stream operation</a>.
	*
	* <p> The reader must not be operated on during the execution of the
	* terminal stream operation. Otherwise, the result of the terminal stream
	* operation is undefined.
	*
	* <p> After execution of the terminal stream operation there are no
	* guarantees that the reader will be at a specific position from which to
	* read the next character or line.
	*
	* <p> If an {@link IOException} is thrown when accessing the underlying
	* {@code BufferedReader}, it is wrapped in an {@link
	* UncheckedIOException} which will be thrown from the {@code Stream}
	* method that caused the read to take place. This method will return a
	* Stream if invoked on a BufferedReader that is closed. Any operation on
	* that stream that requires reading from the BufferedReader after it is
	* closed, will cause an UncheckedIOException to be thrown.
	*
	* @return a {@code Stream<String>} providing the lines of text
	* described by this {@code BufferedReader}
	*
	* @since 1.8
	*/
	public Stream<String> lines() {
	Iterator<String> iter = new Iterator<>() {
	String nextLine = null;

	@Override
	public boolean hasNext() {
	if (nextLine != null) {
	return true;
	} else {
	try {
	nextLine = readLine();
	return (nextLine != null);
	} catch (IOException e) {
	throw new UncheckedIOException(e);
	}
	}
	}

	@Override
	public String next() {
	if (nextLine != null \|\| hasNext()) {
	String line = nextLine;
	nextLine = null;
	return line;
	} else {
	throw new NoSuchElementException();
	}
	}
	};
	return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
	iter, Spliterator.ORDERED \| Spliterator.NONNULL), false);
	}
	}

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