All Downloads are FREE. Search and download functionalities are using the official Maven repository.

java.io.LineNumberReader Maven / Gradle / Ivy

There is a newer version: 1.2.9
Show newest version
/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package java.io;

/**
 * Wraps an existing {@link Reader} and counts the line terminators encountered
 * while reading the data. The line number starts at 0 and is incremented any
 * time {@code '\r'}, {@code '\n'} or {@code "\r\n"} is read. The class has an
 * internal buffer for its data. The size of the buffer defaults to 8 KB.
 */
public class LineNumberReader extends BufferedReader {

    private int lineNumber;

    private int markedLineNumber = -1;

    private boolean lastWasCR;

    private boolean markedLastWasCR;

    /**
     * Constructs a new LineNumberReader on the Reader {@code in}. The internal
     * buffer gets the default size (8 KB).
     *
     * @param in
     *            the Reader that is buffered.
     */
    public LineNumberReader(Reader in) {
        super(in);
    }

    /**
     * Constructs a new LineNumberReader on the Reader {@code in}. The size of
     * the internal buffer is specified by the parameter {@code size}.
     *
     * @param in
     *            the Reader that is buffered.
     * @param size
     *            the size of the buffer to allocate.
     * @throws IllegalArgumentException
     *             if {@code size <= 0}.
     */
    public LineNumberReader(Reader in, int size) {
        super(in, size);
    }

    /**
     * Returns the current line number for this reader. Numbering starts at 0.
     *
     * @return the current line number.
     */
    public int getLineNumber() {
        synchronized (lock) {
            return lineNumber;
        }
    }

    /**
     * Sets a mark position in this reader. The parameter {@code readlimit}
     * indicates how many characters can be read before the mark is invalidated.
     * Sending {@code reset()} will reposition this reader back to the marked
     * position, provided that {@code readlimit} has not been surpassed. The
     * line number associated with this marked position is also stored so that
     * it can be restored when {@code reset()} is called.
     *
     * @param readlimit
     *            the number of characters that can be read from this stream
     *            before the mark is invalidated.
     * @throws IOException
     *             if an error occurs while setting the mark in this reader.
     * @see #markSupported()
     * @see #reset()
     */
    @Override
    public void mark(int readlimit) throws IOException {
        synchronized (lock) {
            super.mark(readlimit);
            markedLineNumber = lineNumber;
            markedLastWasCR = lastWasCR;
        }
    }

    /**
     * Reads a single character from the source reader and returns it as an
     * integer with the two higher-order bytes set to 0. Returns -1 if the end
     * of the source reader has been reached.
     * 

* The line number count is incremented if a line terminator is encountered. * Recognized line terminator sequences are {@code '\r'}, {@code '\n'} and * {@code "\r\n"}. Line terminator sequences are always translated into * {@code '\n'}. * * @return the character read or -1 if the end of the source reader has been * reached. * @throws IOException * if the reader is closed or another IOException occurs. */ @SuppressWarnings("fallthrough") @Override public int read() throws IOException { synchronized (lock) { int ch = super.read(); if (ch == '\n' && lastWasCR) { ch = super.read(); } lastWasCR = false; switch (ch) { case '\r': ch = '\n'; lastWasCR = true; // fall through case '\n': lineNumber++; } return ch; } } /** * Reads up to {@code count} characters from the source reader and stores * them in the character array {@code buffer} starting at {@code offset}. * Returns the number of characters actually read or -1 if no characters * have been read and the end of this reader has been reached. * *

The line number count is incremented if a line terminator is encountered. * Recognized line terminator sequences are {@code '\r'}, {@code '\n'} and * {@code "\r\n"}. * * @throws IOException * if this reader is closed or another IOException occurs. */ @Override public int read(char[] buffer, int offset, int count) throws IOException { synchronized (lock) { int read = super.read(buffer, offset, count); if (read == -1) { return -1; } for (int i = 0; i < read; i++) { char ch = buffer[offset + i]; if (ch == '\r') { lineNumber++; lastWasCR = true; } else if (ch == '\n') { if (!lastWasCR) { lineNumber++; } lastWasCR = false; } else { lastWasCR = false; } } return read; } } /** * Returns the next line of text available from this reader. A line is * represented by 0 or more characters followed by {@code '\r'}, * {@code '\n'}, {@code "\r\n"} or the end of the stream. The returned * string does not include the newline sequence. * * @return the contents of the line or {@code null} if no characters have * been read before the end of the stream has been reached. * @throws IOException * if this reader is closed or another IOException occurs. */ @Override public String readLine() throws IOException { synchronized (lock) { if (lastWasCR) { chompNewline(); lastWasCR = false; } String result = super.readLine(); if (result != null) { lineNumber++; } return result; } } /** * Resets this reader to the last marked location. It also resets the line * count to what is was when this reader was marked. This implementation * resets the source reader. * * @throws IOException * if this reader is already closed, no mark has been set or the * mark is no longer valid because more than {@code readlimit} * bytes have been read since setting the mark. * @see #mark(int) * @see #markSupported() */ @Override public void reset() throws IOException { synchronized (lock) { super.reset(); lineNumber = markedLineNumber; lastWasCR = markedLastWasCR; } } /** * Sets the line number of this reader to the specified {@code lineNumber}. * Note that this may have side effects on the line number associated with * the last marked position. * * @param lineNumber * the new line number value. * @see #mark(int) * @see #reset() */ public void setLineNumber(int lineNumber) { synchronized (lock) { this.lineNumber = lineNumber; } } /** * Skips {@code charCount} characters in this reader. Subsequent calls to * {@code read} will not return these characters unless {@code reset} * is used. This implementation skips {@code charCount} number of characters in * the source reader and increments the line number count whenever line * terminator sequences are skipped. * * @return the number of characters actually skipped. * @throws IllegalArgumentException * if {@code charCount < 0}. * @throws IOException * if this reader is closed or another IOException occurs. * @see #mark(int) * @see #read() * @see #reset() */ @Override public long skip(long charCount) throws IOException { if (charCount < 0) { throw new IllegalArgumentException("charCount < 0: " + charCount); } synchronized (lock) { for (int i = 0; i < charCount; i++) { if (read() == -1) { return i; } } return charCount; } } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy