content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 1996, 2013, 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.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       JDK1.1
   */
  
  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
       *
       * @exception  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 */
                      //
                      // Android-changed: Use the same strategy as BufferedInputStream,
                      // i.e, double the size of the buffer on each fill. Do not directly
                      // size the buffer to the readAheadLimit.
                      //
                      // char ncb[] = new char[readAheadLimit];
                      int nlength = cb.length * 2;
                      if (nlength > readAheadLimit) {
                          nlength = readAheadLimit;
                      }
                      char ncb[] = new char[nlength];
                      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 (<tt>0x00-0xffff</tt>), or -1 if the
       *         end of the stream has been reached
       * @exception  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
       * <code>{@link Reader#read(char[], int, int) read}</code> method of the
       * <code>{@link Reader}</code> class.  As an additional convenience, it
       * attempts to read as many characters as possible by repeatedly invoking
       * the <code>read</code> method of the underlying stream.  This iterated
       * <code>read</code> continues until one of the following conditions becomes
       * true: <ul>
       *
       *   <li> The specified number of characters have been read,
       *
       *   <li> The <code>read</code> method of the underlying stream returns
       *   <code>-1</code>, indicating end-of-file, or
       *
       *   <li> The <code>ready</code> method of the underlying stream
       *   returns <code>false</code>, indicating that further input requests
       *   would block.
       *
       * </ul> If the first <code>read</code> on the underlying stream returns
       * <code>-1</code> to indicate end-of-file then this method returns
       * <code>-1</code>.  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</code>s will not copy data
       * unnecessarily.
       *
       * @param      cbuf  Destination buffer
       * @param      off   Offset at which to start storing characters
       * @param      len   Maximum number of characters to read
       *
       * @return     The number of characters read, or -1 if the end of the
       *             stream has been reached
       *
       * @exception  IOException  If an I/O error occurs
       */
      public int read(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 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'), or a carriage return
       * followed immediately by a linefeed.
       *
       * @param      ignoreLF  If true, the next '\n' will be skipped
       *
       * @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
       *
       * @see        LineNumberReader#readLine()
       *
       * @exception  IOException  If an I/O error occurs
       */
      String readLine(boolean ignoreLF) throws IOException {
          StringBuffer s = null;
          int startChar;
  
          synchronized (lock) {
              ensureOpen();
              boolean omitLF = ignoreLF || skipLF;
  
          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')) {
                          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 StringBuffer(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'), or a carriage return
       * followed immediately by a linefeed.
       *
       * @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
       *
       * @exception  IOException  If an I/O error occurs
       *
       * @see java.nio.file.Files#readAllLines
       */
      public String readLine() throws IOException {
          return readLine(false);
      }
  
      /**
       * Skips characters.
       *
       * @param  n  The number of characters to skip
       *
       * @return    The number of characters actually skipped
       *
       * @exception  IllegalArgumentException  If <code>n</code> is negative.
       * @exception  IOException  If an I/O error occurs
       */
      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.
       *
       * @exception  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.
       *
       * @exception  IllegalArgumentException  If {@code readAheadLimit < 0}
       * @exception  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.
       *
       * @exception  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>() {
              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);
      }
  }
  