java/18 : java.base/java/io/LineNumberReader.java

LineNumberReader
https://openjdk.java.net/
GPLv2 + Classpath Exception
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * accompanied this code).
 *
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 *
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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 at the end of the stream if the last character in the stream is not a line terminator. This number 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, or any of the previous terminators followed by
end of stream, or end of stream not preceded by another terminator.
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 at the end of the
 * stream if the last character in the stream is not a line terminator.  This
 * number 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, or any of the previous terminators followed by
 * end of stream, or end of stream not preceded by another terminator.
 *
 * @author      Mark Reinhold
 * @since       1.1
 */

public class LineNumberReader extends BufferedReader {

    Previous character types /** Previous character types */
    private static final int NONE = 0; // no previous character
    private static final int CHAR = 1; // non-line terminator
    private static final int EOL = 2; // line terminator
    private static final int EOF  = 3; // end-of-file

    The previous character type /** The previous character type */
    private int prevChar = NONE;

    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.  The current line
number is incremented whenever a line terminator is read, or when the
end of the stream is reached and the last character in the stream is
not a line terminator.
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.  The current line
     * number is incremented whenever a line terminator is read, or when the
     * end of the stream is reached and the last character in the stream is
     * not a line terminator.
     *
     * @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++;
                prevChar = EOL;
                return '\n';
            case -1:
                if (prevChar == CHAR)
                    lineNumber++;
                prevChar = EOF;
                break;
            default:
                prevChar = CHAR;
                break;
            }
            return c;
        }
    }

    Reads characters into a portion of an array.  This method will block
until some input is available, an I/O error occurs, or the end of the
stream is reached.
 If len is zero, then no characters are read and 0 is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value -1 is returned; otherwise, at least one character is read and stored into cbuf. 
Line terminators are compressed into single newline
('\n') characters.  The current line number is incremented whenever a
line terminator is read, or when the end of the stream is reached and
the last character in the stream is not a line terminator.
Params: cbuf –  {@inheritDoc}
off –   {@inheritDoc}
len –   {@inheritDoc}
Throws: IndexOutOfBoundsException – {@inheritDoc}
IOException – {@inheritDoc}
Returns:  {@inheritDoc}/**
     * Reads characters into a portion of an array.  This method will block
     * until some input is available, an I/O error occurs, or the end of the
     * stream is reached.
     *
     * <p> If {@code len} is zero, then no characters are read and {@code 0} is
     * returned; otherwise, there is an attempt to read at least one character.
     * If no character is available because the stream is at its end, the value
     * {@code -1} is returned; otherwise, at least one character is read and
     * stored into {@code cbuf}.
     *
     * <p><a href="#lt">Line terminators</a> are compressed into single newline
     * ('\n') characters.  The current line number is incremented whenever a
     * line terminator is read, or when the end of the stream is reached and
     * the last character in the stream is not a line terminator.
     *
     * @param  cbuf  {@inheritDoc}
     * @param  off   {@inheritDoc}
     * @param  len   {@inheritDoc}
     *
     * @return  {@inheritDoc}
     *
     * @throws  IndexOutOfBoundsException {@inheritDoc}
     * @throws  IOException {@inheritDoc}
     */
    @SuppressWarnings("fallthrough")
    public int read(char[] cbuf, int off, int len) throws IOException {
        synchronized (lock) {
            int n = super.read(cbuf, off, len);

            if (n == -1) {
                if (prevChar == CHAR)
                    lineNumber++;
                prevChar = EOF;
                return -1;
            }

            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;
                }
            }

            if (n > 0) {
                switch ((int)cbuf[off + n - 1]) {
                case '\r':
                case '\n':      /* Fall through */
                    prevChar = EOL;
                    break;
                default:
                    prevChar = CHAR;
                    break;
                }
            }

            return n;
        }
    }

    Read a line of text.  Line terminators are compressed
into single newline ('\n') characters. The current line number is
incremented whenever a line terminator is read, or when the end of the
stream is reached and the last character in the stream is not a line
terminator.
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.  <a href="#lt">Line terminators</a> are compressed
     * into single newline ('\n') characters. The current line number is
     * incremented whenever a line terminator is read, or when the end of the
     * stream is reached and the last character in the stream is not a line
     * terminator.
     *
     * @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) {
            boolean[] term = new boolean[1];
            String l = super.readLine(skipLF, term);
            skipLF = false;
            if (l != null) {
                lineNumber++;
                prevChar = term[0] ? EOL : EOF;
            } else { // l == null
                if (prevChar == CHAR)
                    lineNumber++;
                prevChar = EOF;
            }
            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;

    {@inheritDoc}
/**
     * {@inheritDoc}
     */
    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;
            }
            if (n - r > 0) {
                prevChar = NONE;
            }
            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 – {@inheritDoc} off – {@inheritDoc} len – {@inheritDoc}
Throws:	IndexOutOfBoundsException – {@inheritDoc} IOException – {@inheritDoc}
Returns:	{@inheritDoc}
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/ 18/ java.base/java/io/LineNumberReader.java
