gcc/libjava/java/io/CharArrayReader.java

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/* Copyright (C) 1998, 1999 Red Hat, Inc.
1999-04-07 22:42:40 +08:00
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 Warren Levy <warrenl@cygnus.com>
* @date October 16, 1998.
*/
/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
* "The Java Language Specification", ISBN 0-201-63451-1
* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
* Status: Believed complete and correct
*/
public class CharArrayReader extends Reader
{
/* An array of chars provided by the creator of the stream. */
protected char[] buf;
/* Position of the next char in buf to be read. */
protected int pos;
/* The currently marked position in the stream. */
protected int markedPos;
/* The index in buf one greater than the last valid character. */
protected int count;
public CharArrayReader(char[] buffer)
{
this(buffer, 0, buffer.length);
}
public CharArrayReader(char[] buffer, int offset, int length)
{
super();
buf = buffer;
count = offset + length;
if (count > buf.length)
count = buf.length;
pos = offset;
// TBD: What should we do if pos is neg. or > count? E.g. throw exc. or:
// if (pos < 0 || pos > count)
// pos = 0;
markedPos = pos;
}
public void close()
{
synchronized (lock)
{
buf = null;
}
}
public void mark(int readAheadLimit)
{
synchronized (lock)
{
// readAheadLimit is ignored per Java Class Lib. book, p. 318.
markedPos = pos;
}
}
public boolean markSupported()
{
return true;
}
public int read() throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException();
if (pos < 0)
throw new ArrayIndexOutOfBoundsException(pos);
if (pos < count)
return ((int) buf[pos++]) & 0xFFFF;
return -1;
}
}
public int read(char[] b, int off, int len) throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException();
/* 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;
}
}
public boolean ready() throws IOException
{
if (buf == null)
throw new IOException();
return true;
}
public void reset() throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException();
pos = markedPos;
}
}
public long skip(long n) throws IOException
{
synchronized (lock)
{
if (buf == null)
throw new IOException();
// 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;
}
}
}