Method is_constant_singleton

src/expr/src/relation.rs:1130–1136

Checks if `self` is the single element collection with no columns.

(&self)

    /// Checks if `self` is the single element collection with no columns.
    pub fn is_constant_singleton(&self) -> bool {
        if let Some((Ok(rows), typ)) = self.as_const() {
            rows.len() == 1 && typ.column_types.len() == 0 && rows[0].1 == Diff::ONE
        } else {
            false
        }
    }

    /// Constructs the expression for getting a local collection.
    pub fn local_get(id: LocalId, typ: ReprRelationType) -> Self {