/* * @(#)LineNumberReader.java 1.20 03/12/19 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */package java.io;/** * A buffered character-input stream that keeps track of line numbers. * This class defines methods <CODE>void setLineNumber(int)</CODE> and * <CODE>int getLineNumber()</CODE> for setting and getting the current * line number respectively. * <P> * By default, line numbering begins at 0. This number increments as data is * read, and can be changed with a call to <CODE>setLineNumber(int)</CODE>. * Note however, that <CODE>setLineNumber(int)</CODE> does not actually change the current * position in the stream; it only changes the value that will be returned * by <CODE>getLineNumber()</CODE>. * <P> * 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. * * @version 1.20, 03/12/19 * @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. Line terminators are compressed into single * newline ('\n') characters. * * @return The character read, or -1 if the end of the stream has been * reached * * @exception 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. * * @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 * * @exception 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. 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. * * @return 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 * * @exception 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 * * @exception IOException If an I/O error occurs * @exception IllegalArgumentException if <CODE>n</CODE> * 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. * * @exception 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. * * @exception 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; } }}