/*

  * Copyright (c) 1996, 2006, 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

      */

     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

      */

     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;

         }

     }

 }