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package com.salesforce.phoenix.iterate;
import java.sql.SQLException;
import com.salesforce.phoenix.schema.tuple.ResultTuple;
import com.salesforce.phoenix.schema.tuple.Tuple;
abstract public class LookAheadResultIterator implements PeekingResultIterator {
private final static Tuple UNINITIALIZED = new ResultTuple();
private Tuple next = UNINITIALIZED;
abstract protected Tuple advance() throws SQLException;
private void init() throws SQLException {
if (next == UNINITIALIZED) {
next = advance();
}
}
@Override
public Tuple next() throws SQLException {
init();
Tuple next = this.next;
this.next = advance();
return next;
}
@Override
public Tuple peek() throws SQLException {
init();
return next;
}
}