java/11 : java.base/java/io/LineNumberReader.java

LineNumberReader
https://openjdk.java.net/
GPLv2 + Classpath Exception
/*
 * Copyright (c) 1996, 2019, 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 setLineNumber(int) and getLineNumber() for setting and getting the current line number respectively.  By default, line numbering begins at 0. This number increments at every
line terminator as the data is read, and can be changed with a call to setLineNumber(int). Note however, that setLineNumber(int) does not actually change the current position in the stream; it only changes the value that will be returned by getLineNumber(). 
 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.
Author:      Mark Reinhold
Since:       1.1/**
 * 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 {@code setLineNumber(int)}.  Note however, that
 * {@code setLineNumber(int)} does not actually change the current position in
 * the stream; it only changes the value that will be returned by
 * {@code getLineNumber()}.
 *
 * <p> A line is considered to be <a id="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       1.1
 */

public class LineNumberReader extends BufferedReader {

    The current line number /** The current line number */
    private int lineNumber = 0;

    The line number of the mark, if any /** The line number of the mark, if any */
    private int markedLineNumber; // Defaults to 0

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

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

    Create a new line-numbering reader, using the default input-buffer
size.
Params: in – 
        A Reader object to provide the underlying stream/**
     * 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.
Params: in – 
        A Reader object to provide the underlying stream
sz – 
        An int specifying the size of the buffer/**
     * 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.
Params: lineNumber – 
        An int specifying the line number
See Also: getLineNumber/**
     * 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.
See Also: setLineNumber
Returns:  The current line number/**
     * Get the current line number.
     *
     * @return  The current line number
     *
     * @see #setLineNumber
     */
    public int getLineNumber() {
        return lineNumber;
    }

    Read a single character.  Line terminators are
compressed into single newline ('\n') characters.  Whenever a line
terminator is read the current line number is incremented.
Throws: IOException – 
         If an I/O error occurs
Returns:  The character read, or -1 if the end of the stream has been
         reached/**
     * 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 line terminator is read the current line number is
incremented.
Params: cbuf – 
        Destination buffer
off – 
        Offset at which to start storing characters
len – 
        Maximum number of characters to read
Throws: IOException – 
         If an I/O error occurs
IndexOutOfBoundsException – {@inheritDoc}
Returns:  The number of bytes read, or -1 if the end of the stream has
         already been reached/**
     * 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
     *
     * @throws  IndexOutOfBoundsException {@inheritDoc}
     */
    @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 line terminator is
read the current line number is incremented.
Throws: IOException – 
         If an I/O error occurs
Returns:  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/**
     * 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
     *          {@code null} 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 /** Maximum skip-buffer size */
    private static final int maxSkipBufferSize = 8192;

    Skip buffer, null until allocated /** Skip buffer, null until allocated */
    private char skipBuffer[] = null;

    Skip characters.
Params: n – 
        The number of characters to skip
Throws: IOException – 
         If an I/O error occurs
IllegalArgumentException –  If n is negative
Returns:  The number of characters actually skipped/**
     * 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 {@code n} 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.
Params: 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/**
     * 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) {
            // If the most recently read character is '\r', then increment the
            // read ahead limit as in this case if the next character is '\n',
            // two characters would actually be read by the next read().
            if (skipLF)
                readAheadLimit++;
            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/**
     * 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;
        }
    }

}
Params:	lineNumber – An int specifying the line number
See Also:	getLineNumber
Throws:	IOException – If an I/O error occurs
Returns:	The character read, or -1 if the end of the stream has been reached
Params:	cbuf – Destination buffer off – Offset at which to start storing characters len – Maximum number of characters to read
Throws:	IOException – If an I/O error occurs IndexOutOfBoundsException – {@inheritDoc}
Returns:	The number of bytes read, or -1 if the end of the stream has already been reached
Params:	n – The number of characters to skip
Throws:	IOException – If an I/O error occurs IllegalArgumentException – If `n` is negative
Returns:	The number of characters actually skipped
Params:	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
/

java/ 11/ java.base/java/io/LineNumberReader.java
