306 lines
10 KiB
Java
306 lines
10 KiB
Java
/* CharArrayReader.java -- Read an array of characters as a stream
|
|
Copyright (C) 1998, 2001 Free Software Foundation, Inc.
|
|
|
|
This file is part of GNU Classpath.
|
|
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
GNU Classpath 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 for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with GNU Classpath; see the file COPYING. If not, write to the
|
|
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
02111-1307 USA.
|
|
|
|
Linking this library statically or dynamically with other modules is
|
|
making a combined work based on this library. Thus, the terms and
|
|
conditions of the GNU General Public License cover the whole
|
|
combination.
|
|
|
|
As a special exception, the copyright holders of this library give you
|
|
permission to link this library with independent modules to produce an
|
|
executable, regardless of the license terms of these independent
|
|
modules, and to copy and distribute the resulting executable under
|
|
terms of your choice, provided that you also meet, for each linked
|
|
independent module, the terms and conditions of the license of that
|
|
module. An independent module is a module which is not derived from
|
|
or based on this library. If you modify this library, you may extend
|
|
this exception to your version of the library, but you are not
|
|
obligated to do so. If you do not wish to do so, delete this
|
|
exception statement from your version. */
|
|
|
|
|
|
package java.io;
|
|
|
|
/**
|
|
* This class permits an array of chars to be read as an input stream.
|
|
*
|
|
* @author Aaron M. Renn (arenn@urbanophile.com)
|
|
* @author Warren Levy <warrenl@cygnus.com>
|
|
*/
|
|
public class CharArrayReader extends Reader
|
|
{
|
|
/**
|
|
* The array that contains the data supplied during read operations
|
|
*/
|
|
protected char[] buf;
|
|
|
|
/**
|
|
* The array index of the next char to be read from the buffer
|
|
* <code>buf</code>
|
|
*/
|
|
protected int pos;
|
|
|
|
/**
|
|
* The currently marked position in the stream. This defaults to 0, so a
|
|
* reset operation on the stream resets it to read from array index 0 in
|
|
* the buffer - even if the stream was initially created with an offset
|
|
* greater than 0
|
|
*/
|
|
protected int markedPos;
|
|
|
|
/**
|
|
* This indicates the maximum number of chars that can be read from this
|
|
* stream. It is the array index of the position after the last valid
|
|
* char in the buffer <code>buf</code>
|
|
*/
|
|
protected int count;
|
|
|
|
/**
|
|
* Create a new CharArrayReader that will read chars from the passed
|
|
* in char array. This stream will read from the beginning to the end
|
|
* of the array. It is identical to calling an overloaded constructor
|
|
* as <code>CharArrayReader(buf, 0, buf.length)</code>.
|
|
* <p>
|
|
* Note that this array is not copied. If its contents are changed
|
|
* while this stream is being read, those changes will be reflected in the
|
|
* chars supplied to the reader. Please use caution in changing the
|
|
* contents of the buffer while this stream is open.
|
|
*
|
|
* @param buffer The char array buffer this stream will read from.
|
|
*/
|
|
public CharArrayReader(char[] buffer)
|
|
{
|
|
this(buffer, 0, buffer.length);
|
|
}
|
|
|
|
/**
|
|
* Create a new CharArrayReader that will read chars from the passed
|
|
* in char array. This stream will read from position
|
|
* <code>offset</code> in the array for a length of
|
|
* <code>length</code> chars past <code>offset</code>. If the
|
|
* stream is reset to a position before <code>offset</code> then
|
|
* more than <code>length</code> chars can be read from the stream.
|
|
* The <code>length</code> value should be viewed as the array index
|
|
* one greater than the last position in the buffer to read.
|
|
* <p>
|
|
* Note that this array is not copied. If its contents are changed
|
|
* while this stream is being read, those changes will be reflected in the
|
|
* chars supplied to the reader. Please use caution in changing the
|
|
* contents of the buffer while this stream is open.
|
|
*
|
|
* @param buffer The char array buffer this stream will read from.
|
|
* @param offset The index into the buffer to start reading chars from
|
|
* @param length The number of chars to read from the buffer
|
|
*/
|
|
public CharArrayReader(char[] buffer, int offset, int length)
|
|
{
|
|
super();
|
|
if (offset < 0 || length < 0 || offset > buffer.length)
|
|
throw new IllegalArgumentException();
|
|
|
|
buf = buffer;
|
|
|
|
count = offset + length;
|
|
if (count > buf.length)
|
|
count = buf.length;
|
|
|
|
pos = offset;
|
|
markedPos = pos;
|
|
}
|
|
|
|
/**
|
|
* This method closes the stream.
|
|
*/
|
|
public void close()
|
|
{
|
|
synchronized (lock)
|
|
{
|
|
buf = null;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* This method sets the mark position in this stream to the current
|
|
* position. Note that the <code>readlimit</code> parameter in this
|
|
* method does nothing as this stream is always capable of
|
|
* remembering all the chars int it.
|
|
* <p>
|
|
* Note that in this class the mark position is set by default to
|
|
* position 0 in the stream. This is in constrast to some other
|
|
* stream types where there is no default mark position.
|
|
*
|
|
* @param readAheadLimit The number of chars this stream must
|
|
* remember. This parameter is ignored.
|
|
*
|
|
* @exception IOException If an error occurs
|
|
*/
|
|
public void mark(int readAheadLimit) throws IOException
|
|
{
|
|
synchronized (lock)
|
|
{
|
|
if (buf == null)
|
|
throw new IOException("Stream closed");
|
|
// readAheadLimit is ignored per Java Class Lib. book, p. 318.
|
|
markedPos = pos;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* This method overrides the <code>markSupported</code> method in
|
|
* <code>Reader</code> in order to return <code>true</code> -
|
|
* indicating that this stream class supports mark/reset
|
|
* functionality.
|
|
*
|
|
* @return <code>true</code> to indicate that this class supports
|
|
* mark/reset.
|
|
*/
|
|
public boolean markSupported()
|
|
{
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* This method reads one char from the stream. The <code>pos</code>
|
|
* counter is advanced to the next char to be read. The char read
|
|
* is returned as an int in the range of 0-65535. If the stream
|
|
* position is already at the end of the buffer, no char is read and
|
|
* a -1 is returned in order to indicate the end of the stream.
|
|
*
|
|
* @return The char read, or -1 if end of stream
|
|
*/
|
|
public int read() throws IOException
|
|
{
|
|
synchronized (lock)
|
|
{
|
|
if (buf == null)
|
|
throw new IOException("Stream closed");
|
|
|
|
if (pos < 0)
|
|
throw new ArrayIndexOutOfBoundsException(pos);
|
|
|
|
if (pos < count)
|
|
return ((int) buf[pos++]) & 0xFFFF;
|
|
return -1;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* This method reads chars from the stream and stores them into a
|
|
* caller supplied buffer. It starts storing the data at index
|
|
* <code>offset</code> into the buffer and attempts to read
|
|
* <code>len</code> chars. This method can return before reading
|
|
* the number of chars requested if the end of the stream is
|
|
* encountered first. The actual number of chars read is returned.
|
|
* If no chars can be read because the stream is already at the end
|
|
* of stream position, a -1 is returned.
|
|
* <p>
|
|
* This method does not block.
|
|
*
|
|
* @param b The array into which the chars read should be stored.
|
|
* @param off The offset into the array to start storing chars
|
|
* @param len The requested number of chars to read
|
|
*
|
|
* @return The actual number of chars read, or -1 if end of stream.
|
|
*/
|
|
public int read(char[] b, int off, int len) throws IOException
|
|
{
|
|
synchronized (lock)
|
|
{
|
|
if (buf == null)
|
|
throw new IOException("Stream closed");
|
|
|
|
/* Don't need to check pos value, arraycopy will check it. */
|
|
if (off < 0 || len < 0 || off + len > b.length)
|
|
throw new ArrayIndexOutOfBoundsException();
|
|
|
|
if (pos >= count)
|
|
return -1;
|
|
|
|
int numChars = Math.min(count - pos, len);
|
|
System.arraycopy(buf, pos, b, off, numChars);
|
|
pos += numChars;
|
|
return numChars;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Return true if more characters are available to be read.
|
|
*
|
|
* @return <code>true</code> to indicate that this stream is ready
|
|
* to be read.
|
|
*
|
|
* @specnote The JDK 1.3 API docs are wrong here. This method will
|
|
* return false if there are no more characters available.
|
|
*/
|
|
public boolean ready() throws IOException
|
|
{
|
|
if (buf == null)
|
|
throw new IOException("Stream closed");
|
|
|
|
return (pos < count);
|
|
}
|
|
|
|
/**
|
|
* This method sets the read position in the stream to the mark
|
|
* point by setting the <code>pos</code> variable equal to the
|
|
* <code>mark</code> variable. Since a mark can be set anywhere in
|
|
* the array, the mark/reset methods int this class can be used to
|
|
* provide random search capabilities for this type of stream.
|
|
*/
|
|
public void reset() throws IOException
|
|
{
|
|
synchronized (lock)
|
|
{
|
|
if (buf == null)
|
|
throw new IOException("Stream closed");
|
|
|
|
pos = markedPos;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* This method attempts to skip the requested number of chars in the
|
|
* input stream. It does this by advancing the <code>pos</code> value by the
|
|
* specified number of chars. It this would exceed the length of the
|
|
* buffer, then only enough chars are skipped to position the stream at
|
|
* the end of the buffer. The actual number of chars skipped is returned.
|
|
*
|
|
* @param n The requested number of chars to skip
|
|
*
|
|
* @return The actual number of chars skipped.
|
|
*/
|
|
public long skip(long n) throws IOException
|
|
{
|
|
synchronized (lock)
|
|
{
|
|
if (buf == null)
|
|
throw new IOException("Stream closed");
|
|
|
|
// Even though the var numChars is a long, in reality it can never
|
|
// be larger than an int since the result of subtracting 2 positive
|
|
// ints will always fit in an int. Since we have to return a long
|
|
// anyway, numChars might as well just be a long.
|
|
long numChars = Math.min((long) (count - pos), n < 0 ? 0L : n);
|
|
pos += numChars;
|
|
return numChars;
|
|
}
|
|
}
|
|
}
|