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// java.io.SequenceInputStream
// An implementation of the Java Language Specification section 22.8
// Written by Charles Briscoe-Smith; refer to the file LEGAL for details.
package java.io;
import java.util.Enumeration;
class StreamPair implements Enumeration {
private InputStream s1, s2;
StreamPair(InputStream s1, InputStream s2) { this.s1=s1; this.s2=s2; }
public boolean hasMoreElements() { return s1!=null || s2!=null; }
public Object nextElement()
{
Object rv=s1; s1=null;
if (rv==null) { rv=s2; s2=null; }
return rv;
}
}
public class SequenceInputStream extends InputStream {
private Enumeration source;
private InputStream cur;
public SequenceInputStream(Enumeration e)
{
source=e;
}
public SequenceInputStream(InputStream s1, InputStream s2)
{
source=new StreamPair(s1, s2);
}
public int read() throws IOException
{
if (cur==null)
if (source.hasMoreElements())
cur=(InputStream) source.nextElement();
else
return -1;
int rv=cur.read();
if (rv==-1) {
cur.close();
cur=null;
return read();
}
return rv;
}
public int read(byte[] b, int off, int len)
throws IOException, NullPointerException,
IndexOutOfBoundsException
{
if (cur==null)
if (source.hasMoreElements())
cur=(InputStream) source.nextElement();
else
return -1;
int rv=cur.read(b, off, len);
if (rv==-1) {
cur.close();
cur=null;
return read(b, off, len);
}
return rv;
}
public void close() throws IOException
{
if (cur!=null) cur.close();
while (source.hasMoreElements())
((InputStream) source.nextElement()).close();
}
}
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