// GetBinaryBounds gets the binary encoding of the upper and lower bounds of
// the inequality filter on fq, if any is defined. If a bound does not exist,
// it is nil.
//
// NOTE: if fq specifies a descending sort order for the inequality, the bounds
// will be inverted, incremented, and flipped.
func GetBinaryBounds(fq *ds.FinalizedQuery) (lower, upper []byte) {
// Pick up the start/end range from the inequalities, if any.
//
// start and end in the reducedQuery are normalized so that `start >=
// X < end`. Because of that, we need to tweak the inequality filters
// contained in the query if they use the > or <= operators.
if ineqProp := fq.IneqFilterProp(); ineqProp != "" {
_, startOp, startV := fq.IneqFilterLow()
if startOp != "" {
lower = serialize.ToBytes(startV)
if startOp == ">" {
lower = increment(lower)
}
}
_, endOp, endV := fq.IneqFilterHigh()
if endOp != "" {
upper = serialize.ToBytes(endV)
if endOp == "<=" {
upper = increment(upper)
}
}
// The inequality is specified in natural (ascending) order in the query's
// Filter syntax, but the order information may indicate to use a descending
// index column for it. If that's the case, then we must invert, swap and
// increment the inequality endpoints.
//
// Invert so that the desired numbers are represented correctly in the index.
// Swap so that our iterators still go from >= start to < end.
// Increment so that >= and < get correctly bounded (since the iterator is
// still using natrual bytes ordering)
if fq.Orders()[0].Descending {
hi, lo := []byte(nil), []byte(nil)
if len(lower) > 0 {
lo = increment(serialize.Invert(lower))
}
if len(upper) > 0 {
hi = increment(serialize.Invert(upper))
}
upper, lower = lo, hi
}
}
return
}