func newSargAnd(pred *expression.And) *sargAnd {
rv := &sargAnd{}
rv.sarger = func(expr2 expression.Expression) (spans plan.Spans, err error) {
if SubsetOf(pred, expr2) {
return _SELF_SPANS, nil
}
var s plan.Spans
for _, op := range pred.Operands() {
s, err = sargFor(op, expr2, rv.MissingHigh())
if err != nil {
return nil, err
}
if len(s) == 0 {
continue
}
if len(spans) == 0 {
spans = s.Copy()
} else {
spans = constrainSpans(spans, s)
}
}
return
}
return rv
}
func constrainSpans(spans1, spans2 plan.Spans) plan.Spans {
if len(spans2) != 1 {
if len(spans1) == 1 {
spans1, spans2 = spans2.Copy(), spans1
} else {
return spans1
}
}
span2 := spans2[0]
for _, span1 := range spans1 {
constrainSpan(span1, span2)
}
return spans1
}