Method find_bound_expr

src/expr/src/relation/join_input_mapper.rs:296–311

Takes an expression in the global context and looks in `equivalences` for an equivalent expression (also expressed in the global context) that belongs to one or more of the inputs in `bound_inputs` # Examples ``` use mz_repr::{Datum, ReprColumnType, ReprRelationType, ReprScalarType}; use mz_expr::{JoinInputMapper, MirRelationExpr, MirScalarExpr}; // A two-column schema common to each of the thr

(
        &self,
        expr: &C,
        bound_inputs: &[usize],
        equivalences: &[Vec<C>],
    )

    /// );
    /// ```
    pub fn find_bound_expr<C: Columns + Clone + Eq>(
        &self,
        expr: &C,
        bound_inputs: &[usize],
        equivalences: &[Vec<C>],
    ) -> Option<C> {
        if let Some(equivalence) = equivalences.iter().find(|equivs| equivs.contains(expr)) {
            if let Some(bound_expr) = equivalence
                .iter()
                .find(|expr| self.lookup_inputs(*expr).all(|i| bound_inputs.contains(&i)))
            {
                return Some(bound_expr.clone());
            }
        }
        None
    }

    /// Try to rewrite `expr` from the global context so that all the
    /// columns point to the `index`th input by replacing subexpressions with their