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/* * 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;        }    } }