gcc/libjava/java/io/LineNumberReader.java

/* Copyright (C) 1998, 1999  Cygnus Solutions

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */
 
package java.io;

/**
 * @author Per Bothner <bothner@cygnus.com>
 * @date April 22, 1998.  
 */
/* Written using "Java Class Libraries", 2nd edition, plus online
 * API docs for JDK 1.2 beta from http://www.javasoft.com.
 * Status:  Believed complete and correct.
 *
 * This implementation has the feature that if '\r' is read, it
 * does not look for a '\n', but immediately returns '\n'.
 * On the next read(), if a '\n' is read, it is skipped.
 * This has the advantage that we do not read (and hang) unnecessarily.
 *
 * This implementation is also minimal in the number of fields it uses.
 */

public class LineNumberReader extends BufferedReader
{
  /** The current line number. */
  int lineNumber;

  public LineNumberReader(Reader in)
  {
    super(in, 8192);
  }

  public LineNumberReader(Reader in, int size)
  {
    super(in, size);
  }

  public int getLineNumber()
  {
    return lineNumber;
  }

  public void setLineNumber(int lineNumber)
  {
    this.lineNumber = lineNumber;
  }

  private static int countLines (char[] buffer, int off, int len)
  {
    int count = 0;
    char prev = '\0';
    for (int i = 0;  i < len;  i++)
      {
        char ch = buffer[i+off];
        if ((ch == '\n' && prev != '\r') || ch == '\r')
          count++;
        prev = ch;
      }
    return count;
  }

  public void mark(int readLimit) throws IOException
  {
    synchronized (lock)
      {
	// This is basically the same as BufferedReader.mark.
	// However, if the previous character was a '\r', we need to
	// save that 'r', in case the next character is a '\n'.
	if (pos + readLimit > limit)
	  {
	    int saveCR = (pos > 0 && buffer[pos-1] == '\r') ? 1 : 0;
	    char[] old_buffer = buffer;
	    if (readLimit > limit)
	      buffer = new char[saveCR + readLimit];
	    int copy_start = pos - saveCR;
	    limit -= copy_start;
	    System.arraycopy(old_buffer, copy_start, buffer, 0, limit);
	    pos = saveCR;
	  }
	markPos = pos;
      }
  }

  public void reset() throws IOException
  {
    synchronized (lock)
      {
	if (markPos < 0)
	  throw new IOException("mark never set or invalidated");
	if (markPos > 0 && pos > markPos && buffer[markPos-1] == '\r'
	    && buffer[markPos] == '\n')
	  lineNumber--;
	lineNumber -= countLines(buffer, pos, markPos);
	pos = markPos;
      }
  }

  public int read() throws IOException
  {
    synchronized (lock)
      {
	skipRedundantLF();
	if (pos >= limit)
	  {
	    if (markPos >= 0 && limit == buffer.length)
	      markPos = -1;
	    if (markPos <= 0)
	      pos = limit = 0;
	    int count = in.read(buffer, limit, buffer.length - limit);
	    if (count <= 0)
	      return -1;
	    limit += count;
	  }
	char ch = buffer[pos++];
	if (ch == '\r' || ch == '\n')
	  {
	    lineNumber++;
	    return '\n';
	  }
	return (int) ch;
      }
  }

  public int read(char[] buf, int offset, int count) throws IOException
  {
    if (count <= 0)
      {
	if (count < 0)
	  throw new IndexOutOfBoundsException();
	return 0;
      }
    synchronized (lock)
      {
	int first = read();
	if (first < 0)
	  return -1;
	int start_offset = offset;
	buf[offset++] = (char) first;
	if (buffer[pos-1] == '\r' && pos < limit && buffer[pos] == '\n')
	  pos++;
	count--;
	while (count-- > 0 && pos < limit)
	  {
	    char ch = buffer[pos++];
	    if (ch == '\r')
	      {
		lineNumber++;
		ch = '\n';
		if (pos < limit && buffer[pos] == '\n')
		  pos++;
	      }
	    else if (ch == '\n')
	      lineNumber++;
	    buf[offset++] = ch;
	  }
	return offset - start_offset;
      }
  }

  private void skipRedundantLF() throws IOException
  {
    if (pos > 0 && buffer[pos-1] == '\r')
      {
	if (pos < limit)
	  { // fast case
	    if (buffer[pos] == '\n')
	      pos++;
	  }
	else
	  { // use read() to deal with the general case.
	    // Set pos and limit to zero to avoid infinite recursion in read.
	    // May need to invalidate markPos if we've exceeded the buffer.  
	    if (pos >= buffer.length)
	      markPos = -1;
	    pos = limit = 0;
	    int ch = read();
	    if (ch >= 0 && ch != '\n')
	      pos--;
	  }
      }
  }

  public String readLine() throws IOException
  {
    // BufferedReader.readLine already does this.  Shouldn't need to keep
    // track of newlines (since the read method deals with this for us).
    // But if the buffer is large, we may not call the read method at all
    // and super.readLine can't increment lineNumber itself.
    // Though it may seem kludgy, the safest thing to do is to save off
    // lineNumber and increment it explicitly when we're done (iff we
    // ended with a '\n' or '\r' as opposed to EOF).
    //
    // Also, we need to undo the special casing done by BufferedReader.readLine
    // when a '\r' is the last char in the buffer.  That situation is marked
    // by 'pos > limit'.
    int tmpLineNumber = lineNumber;
    skipRedundantLF();
    String str = super.readLine();
    if (pos > limit)
      --pos;

    int ch;
    if (pos > 0 && ((ch = buffer[pos - 1]) == '\n' || ch == '\r'))
      lineNumber = tmpLineNumber + 1;

    return str;
  }

  public long skip(long count) throws IOException
  {
    if (count <= 0)
      return 0;
    long to_do = count;
    do
      {
	int ch = read();
	if (ch < 0)
	  break;
	to_do--;
	if (ch == '\n' || ch == '\r')
	  lineNumber++;
	else
	  {
	    long fence = pos + to_do;
	    if (limit < fence)
	      fence = limit;
	    int end = pos;
	    for (; end < fence; end++)
	      {
		char endch = buffer[end];
		if (endch == '\n' || endch == '\r')
		  break;
	      }
	    to_do -= end - pos;
	    pos = end;
	  }
      }
    while (to_do > 0);
    return count - to_do;
  }
}