Struct mz_transform::equivalence_propagation::EquivalencePropagation

pub struct EquivalencePropagation;

Pulls up and pushes down predicate information represented as equivalences

Implementations

impl EquivalencePropagation

pub fn apply( &self, expr: &mut MirRelationExpr, derived: DerivedView<'_>, outer_equivalences: EquivalenceClasses, get_equivalences: &mut BTreeMap<Id, EquivalenceClasses>, )

Provides the opportunity to mutate relation in response to equivalences enforced by others.

Provides the opportunity to mutate relation in response to equivalences enforced by their children, as presented in derived, and equivalences enforced of their output (by their ancestors), as presented in outer_equivalences and get_equivalences.

The mutations should never invalidate an equivalence the operator has been reported as providing, as that information may have already been acted upon by others.

The expr_index argument must equal exprs position in post-order, so that it can be used as a reference into derived. The argument can be used with the SubtreeSize analysis to determine the range of values associated with expr.

After the call, get_equivalences will be populated with certainly equivalences that will be certainly enforced for all uses of each identifier. The information can be harvested and propagated to the definitions of those identifiers.

Trait Implementations

impl Debug for EquivalencePropagation

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for EquivalencePropagation

fn default() -> EquivalencePropagation

Returns the “default value” for a type.

impl Transform for EquivalencePropagation

fn name(&self) -> &'static str

A short string naming the transform, as it will be reported in metrics.

fn actually_perform_transform( &self, relation: &mut MirRelationExpr, ctx: &mut TransformCtx<'_>, ) -> Result<(), TransformError>

Transform a relation into a functionally equivalent relation.

fn transform( &self, relation: &mut MirRelationExpr, args: &mut TransformCtx<'_>, ) -> Result<(), TransformError>

Transforms a relation into a functionally equivalent relation.

fn debug(&self) -> String

A string describing the transform.