package org.iq80.leveldb.util;
import org.iq80.leveldb.table.Block;
import org.iq80.leveldb.table.BlockIterator;
import org.iq80.leveldb.table.Table;
import java.util.Map.Entry;
public final class TableIterator extends AbstractSeekingIterator<Slice, Slice>
{
private final Table table;
private final BlockIterator blockIterator;
private BlockIterator current;
public TableIterator(Table table, BlockIterator blockIterator)
{
this.table = table;
this.blockIterator = blockIterator;
current = null;
}
@Override
protected void seekToFirstInternal()
{
// reset index to before first and clear the data iterator
blockIterator.seekToFirst();
current = null;
}
@Override
protected void seekInternal(Slice targetKey)
{
// seek the index to the block containing the key
blockIterator.seek(targetKey);
// if indexIterator does not have a next, it mean the key does not exist in this iterator
if (blockIterator.hasNext()) {
// seek the current iterator to the key
current = getNextBlock();
current.seek(targetKey);
}
else {
current = null;
}
}
@Override
protected Entry<Slice, Slice> getNextElement()
{
// note: it must be here & not where 'current' is assigned,
// because otherwise we'll have called inputs.next() before throwing
// the first NPE, and the next time around we'll call inputs.next()
// again, incorrectly moving beyond the error.
boolean currentHasNext = false;
while (true) {
if (current != null) {
currentHasNext = current.hasNext();
}
if (!(currentHasNext)) {
if (blockIterator.hasNext()) {
current = getNextBlock();
}
else {
break;
}
}
else {
break;
}
}
if (currentHasNext) {
return current.next();
}
else {
// set current to empty iterator to avoid extra calls to user iterators
current = null;
return null;
}
}
private BlockIterator getNextBlock()
{
Slice blockHandle = blockIterator.next().getValue();
Block dataBlock = table.openBlock(blockHandle);
return dataBlock.iterator();
}
@Override
public String toString()
{
final StringBuilder sb = new StringBuilder();
sb.append("ConcatenatingIterator");
sb.append("{blockIterator=").append(blockIterator);
sb.append(", current=").append(current);
sb.append('}');
return sb.toString();
}
}