com.unit16.z.io.Source Maven / Gradle / Ivy
package com.unit16.z.io;
import java.io.Closeable;
import java.io.IOException;
import java.util.Iterator;
public interface Source extends Closeable {
public A next() throws IOException;
/**
* @return true exactly if the source is open (has not been closed -- {@link #close()})
* and we expect to be able to read another item from it.
*
* @throws IOException .
*/
public boolean hasNext() throws IOException;
public static final class Empty
implements Source
{
@Override
public void close() {}
@Override
public C next() throws IOException { throw new IOException("Empty."); }
@Override
public boolean hasNext() { return false; }
}
public static final class Sequential
implements Source
{
private final Iterator> _iter;
private Source _curr;
private boolean hasNext = false;
public Sequential(Iterator> i) throws IOException
{
_iter = i;
_curr = _iter.hasNext() ? _iter.next() : new Empty();
advance();
}
@Override
public void close() throws IOException {
_curr.close();
while (_iter.hasNext())
{
_iter.next().close();
}
}
@Override
public B next() throws IOException {
final B n = _curr.next();
advance();
return n;
}
private void advance() throws IOException {
while (!_curr.hasNext() && _iter.hasNext())
{
_curr.close();
_curr = _iter.next();
}
hasNext = _curr.hasNext();
}
@Override
public boolean hasNext() { return hasNext; }
}
}