func (this *sargFactory) VisitLike(expr *expression.Like) (interface{}, error) {
return newSargLike(expr, expr.Regexp()), nil
}
func (this *DNF) VisitLike(expr *expression.Like) (interface{}, error) {
err := expr.MapChildren(this)
if err != nil {
return nil, err
}
re := expr.Regexp()
if re == nil {
return expr, nil
}
prefix, complete := re.LiteralPrefix()
if complete {
eq := expression.NewEq(expr.First(), expression.NewConstant(prefix))
return eq, nil
}
if prefix == "" {
return expr, nil
}
var and expression.Expression
le := expression.NewLE(expression.NewConstant(prefix), expr.First())
last := len(prefix) - 1
if prefix[last] < math.MaxUint8 {
bytes := []byte(prefix)
bytes[last]++
and = expression.NewAnd(le, expression.NewLT(
expr.First(),
expression.NewConstant(string(bytes))))
} else {
and = expression.NewAnd(le, expression.NewLT(
expr.First(),
expression.EMPTY_ARRAY_EXPR))
}
return and, nil
}