Struct Rule

pub struct Rule {
    pub pos: Pos,
    pub equals: DisjointSets<BindingId>,
    pub iterators: StableSet<BindingId>,
    pub prio: i64,
    pub impure: Vec<BindingId>,
    pub result: BindingId,
    /* private fields */
}

A term-rewriting rule. All BindingIds are only meaningful in the context of the RuleSet that contains this rule.

Fields

pos: Pos

Where was this rule defined?

equals: DisjointSets<BindingId>

Sets of bindings which must be equal for this rule to match.

iterators: StableSet<BindingId>

These bindings are from multi-terms which need to be evaluated in this rule.

prio: i64

If other rules apply along with this one, the one with the highest numeric priority is evaluated. If multiple applicable rules have the same priority, that’s an overlap error.

impure: Vec<BindingId>

If this rule applies, these side effects should be evaluated before returning.

result: BindingId

If this rule applies, the top-level term should evaluate to this expression.

Implementations

impl Rule

pub fn may_overlap(&self, other: &Rule) -> Overlap

Returns whether a given pair of rules can both match on some input, and if so, whether either matches a subset of the other’s inputs. If this function returns No, then the two rules definitely do not overlap. However, it may return Yes in cases where the rules can’t overlap in practice, or where this analysis is not yet precise enough to decide.

pub fn total_constraints(&self) -> usize

Returns the total number of binding sites which this rule constrains, with either a concrete pattern or an equality constraint.

pub fn get_constraint(&self, source: BindingId) -> Option<Constraint>

Returns the constraint that the given binding site must satisfy for this rule to match, if there is one.

Trait Implementations

impl Debug for Rule

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

Formats the value using the given formatter.

impl Default for Rule

fn default() -> Rule

Returns the “default value” for a type.