Method is_unknown

datafusion/expr-common/src/interval_arithmetic.rs:1917–1925

Returns the set of possible values after applying the `is unknown` test on all values in this set. The resulting set can only contain 'TRUE' and/or 'FALSE', never 'UNKNOWN'.

(&self)

    /// values in this set.
    /// The resulting set can only contain 'TRUE' and/or 'FALSE', never 'UNKNOWN'.
    pub fn is_unknown(&self) -> Result<Self> {
        let (t, f, u) = self.is_true_false_unknown()?;

        match (t, f, u) {
            (false, false, true) => Ok(Self::TRUE),
            (_, _, true) => Ok(Self::TRUE_OR_FALSE),
            (_, _, false) => Ok(Self::FALSE),
        }
    }

    /// Returns a tuple of booleans indicating if this interval contains the
    /// true, false, and unknown truth values respectively.