(
&self,
expr: &MirRelationExpr,
index: usize,
results: &[Self::Value],
depends: &Derived,
)
| 46 | } |
| 47 | |
| 48 | fn derive( |
| 49 | &self, |
| 50 | expr: &MirRelationExpr, |
| 51 | index: usize, |
| 52 | results: &[Self::Value], |
| 53 | depends: &Derived, |
| 54 | ) -> Self::Value { |
| 55 | let mut equivalences = match expr { |
| 56 | MirRelationExpr::Constant { rows, typ } => { |
| 57 | // Trawl `rows` for any constant information worth recording. |
| 58 | // Literal columns may be valuable; non-nullability could be too. |
| 59 | let mut equivalences = EquivalenceClasses::default(); |
| 60 | if let Ok([(row, _cnt), rows @ ..]) = rows.as_deref() { |
| 61 | // Vector of `Option<Datum>` which becomes `None` once a column has a second datum. |
| 62 | let len = row.iter().count(); |
| 63 | let mut common = Vec::with_capacity(len); |
| 64 | common.extend(row.iter().map(Some)); |
| 65 | // Prep initial nullability information. |
| 66 | let mut nullable_cols = common |
| 67 | .iter() |
| 68 | .map(|datum| datum == &Some(Datum::Null)) |
| 69 | .collect::<Vec<_>>(); |
| 70 | |
| 71 | for (row, _cnt) in rows.iter() { |
| 72 | for ((datum, common), nullable) in row |
| 73 | .iter() |
| 74 | .zip_eq(common.iter_mut()) |
| 75 | .zip_eq(nullable_cols.iter_mut()) |
| 76 | { |
| 77 | if Some(datum) != *common { |
| 78 | *common = None; |
| 79 | } |
| 80 | if datum == Datum::Null { |
| 81 | *nullable = true; |
| 82 | } |
| 83 | } |
| 84 | } |
| 85 | for (index, common) in common.into_iter().enumerate() { |
| 86 | if let Some(datum) = common { |
| 87 | equivalences.classes.push(vec![ |
| 88 | MirScalarExpr::column(index), |
| 89 | MirScalarExpr::literal_ok( |
| 90 | datum, |
| 91 | typ.column_types[index].scalar_type.clone(), |
| 92 | ), |
| 93 | ]); |
| 94 | } |
| 95 | } |
| 96 | // If any columns are non-null, introduce this fact. |
| 97 | if nullable_cols.iter().any(|x| !*x) { |
| 98 | let mut class = vec![MirScalarExpr::literal_false()]; |
| 99 | for (index, nullable) in nullable_cols.iter().enumerate() { |
| 100 | if !*nullable { |
| 101 | class.push(MirScalarExpr::column(index).call_is_null()); |
| 102 | } |
| 103 | } |
| 104 | equivalences.classes.push(class); |
| 105 | } |
nothing calls this directly
no test coverage detected