content: /*
   * Copyright (c) 1996, 2011, 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;
  
  
  /**
   * A buffered character-input stream that keeps track of line numbers.  This
   * class defines methods {@link #setLineNumber(int)} and {@link
   * #getLineNumber()} for setting and getting the current line number
   * respectively.
   *
   * <p> By default, line numbering begins at 0. This number increments at every
   * <a href="#lt">line terminator</a> as the data is read, and can be changed
   * with a call to <tt>setLineNumber(int)</tt>.  Note however, that
   * <tt>setLineNumber(int)</tt> does not actually change the current position in
   * the stream; it only changes the value that will be returned by
   * <tt>getLineNumber()</tt>.
   *
   * <p> A line is considered to be <a name="lt">terminated</a> by any one of a
   * line feed ('\n'), a carriage return ('\r'), or a carriage return followed
   * immediately by a linefeed.
   *
   * @author      Mark Reinhold
   * @since       JDK1.1
   */
  
  public class LineNumberReader extends BufferedReader {
  
      /** The current line number */
      private int lineNumber = 0;
  
      /** The line number of the mark, if any */
      private int markedLineNumber; // Defaults to 0
  
      /** If the next character is a line feed, skip it */
      private boolean skipLF;
  
      /** The skipLF flag when the mark was set */
      private boolean markedSkipLF;
  
      /**
       * Create a new line-numbering reader, using the default input-buffer
       * size.
       *
       * @param  in
       *         A Reader object to provide the underlying stream
       */
      public LineNumberReader(Reader in) {
          super(in);
      }
  
      /**
       * Create a new line-numbering reader, reading characters into a buffer of
       * the given size.
       *
       * @param  in
       *         A Reader object to provide the underlying stream
       *
       * @param  sz
       *         An int specifying the size of the buffer
       */
      public LineNumberReader(Reader in, int sz) {
          super(in, sz);
      }
  
      /**
       * Set the current line number.
       *
       * @param  lineNumber
       *         An int specifying the line number
       *
       * @see #getLineNumber
       */
      public void setLineNumber(int lineNumber) {
          this.lineNumber = lineNumber;
      }
  
      /**
       * Get the current line number.
       *
       * @return  The current line number
       *
       * @see #setLineNumber
       */
      public int getLineNumber() {
          return lineNumber;
      }
  
      /**
       * Read a single character.  <a href="#lt">Line terminators</a> are
       * compressed into single newline ('\n') characters.  Whenever a line
       * terminator is read the current line number is incremented.
       *
       * @return  The character read, or -1 if the end of the stream has been
       *          reached
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      @SuppressWarnings("fallthrough")
      public int read() throws IOException {
          synchronized (lock) {
              int c = super.read();
              if (skipLF) {
                  if (c == '\n')
                      c = super.read();
                  skipLF = false;
              }
              switch (c) {
              case '\r':
                  skipLF = true;
              case '\n':          /* Fall through */
                  lineNumber++;
                  return '\n';
              }
              return c;
          }
      }
  
      /**
       * Read characters into a portion of an array.  Whenever a <a
       * href="#lt">line terminator</a> is read the current line number is
       * incremented.
       *
       * @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 bytes read, or -1 if the end of the stream has
       *          already been reached
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      @SuppressWarnings("fallthrough")
      public int read(char cbuf[], int off, int len) throws IOException {
          synchronized (lock) {
              int n = super.read(cbuf, off, len);
  
              for (int i = off; i < off + n; i++) {
                  int c = cbuf[i];
                  if (skipLF) {
                      skipLF = false;
                      if (c == '\n')
                          continue;
                  }
                  switch (c) {
                  case '\r':
                      skipLF = true;
                  case '\n':      /* Fall through */
                      lineNumber++;
                      break;
                  }
              }
  
              return n;
          }
      }
  
      /**
       * Read a line of text.  Whenever a <a href="#lt">line terminator</a> is
       * read the current line number is incremented.
       *
       * @return  A String containing the contents of the line, not including
       *          any <a href="#lt">line termination characters</a>, or
       *          <tt>null</tt> if the end of the stream has been reached
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      public String readLine() throws IOException {
          synchronized (lock) {
              String l = super.readLine(skipLF);
              skipLF = false;
              if (l != null)
                  lineNumber++;
              return l;
          }
      }
  
      /** Maximum skip-buffer size */
      private static final int maxSkipBufferSize = 8192;
  
      /** Skip buffer, null until allocated */
      private char skipBuffer[] = null;
  
      /**
       * Skip characters.
       *
       * @param  n
       *         The number of characters to skip
       *
       * @return  The number of characters actually skipped
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @throws  IllegalArgumentException
       *          If <tt>n</tt> is negative
       */
      public long skip(long n) throws IOException {
          if (n < 0)
              throw new IllegalArgumentException("skip() value is negative");
          int nn = (int) Math.min(n, maxSkipBufferSize);
          synchronized (lock) {
              if ((skipBuffer == null) || (skipBuffer.length < nn))
                  skipBuffer = new char[nn];
              long r = n;
              while (r > 0) {
                  int nc = read(skipBuffer, 0, (int) Math.min(r, nn));
                  if (nc == -1)
                      break;
                  r -= nc;
              }
              return n - r;
          }
      }
  
      /**
       * Mark the present position in the stream.  Subsequent calls to reset()
       * will attempt to reposition the stream to this point, and will also reset
       * the line number appropriately.
       *
       * @param  readAheadLimit
       *         Limit on the number of characters that may be read while still
       *         preserving the mark.  After reading this many characters,
       *         attempting to reset the stream may fail.
       *
       * @throws  IOException
       *          If an I/O error occurs
       */
      public void mark(int readAheadLimit) throws IOException {
          synchronized (lock) {
              super.mark(readAheadLimit);
              markedLineNumber = lineNumber;
              markedSkipLF     = skipLF;
          }
      }
  
      /**
       * Reset the stream to the most recent mark.
       *
       * @throws  IOException
       *          If the stream has not been marked, or if the mark has been
       *          invalidated
       */
      public void reset() throws IOException {
          synchronized (lock) {
              super.reset();
              lineNumber = markedLineNumber;
              skipLF     = markedSkipLF;
          }
      }
  
  }
  