func newSubsetLike(expr expression.BinaryFunction, re *regexp.Regexp) expression.Visitor { if re == nil { // Pattern is not a constant return newSubsetDefault(expr) } prefix, complete := re.LiteralPrefix() if complete { eq := expression.NewEq(expr.First(), expression.NewConstant(prefix)) return newSubsetEq(eq.(*expression.Eq)) } if prefix == "" { return newSubsetDefault(expr) } 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)) } sand := newSubsetAnd(and.(*expression.And)) rv := &subsetLike{} rv.test = func(expr2 expression.Expression) (bool, error) { if expr.EquivalentTo(expr2) { return true, nil } return sand.test(expr2) } return rv }