[−][src]Trait chalk_ir::visit::Visitor
A "visitor" recursively folds some term -- that is, some bit of IR,
such as a Goal
, and computes a value as a result.
To apply a visitor, use the Visit::visit_with
method, like so
let result = x.visit_with(&mut visitor, 0);
Associated Types
type Result: VisitResult
Required methods
fn as_dyn(&mut self) -> &mut dyn Visitor<'i, I, Result = Self::Result>
Creates a dyn
value from this visitor. Unfortunately, this
must be added manually to each impl of visitor; it permits the
default implements below to create a &mut dyn Visitor
from
Self
without knowing what Self
is (by invoking this
method). Effectively, this limits impls of visitor
to types
for which we are able to create a dyn value (i.e., not [T]
types).
fn interner(&self) -> &'i I
Provided methods
fn visit_ty(&mut self, ty: &Ty<I>, outer_binder: DebruijnIndex) -> Self::Result
Top-level callback: invoked for each Ty<I>
that is
encountered when visiting. By default, invokes
super_visit_with
, which will in turn invoke the more
specialized visiting methods below, like visit_free_var
.
fn visit_lifetime(
&mut self,
lifetime: &Lifetime<I>,
outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
lifetime: &Lifetime<I>,
outer_binder: DebruijnIndex
) -> Self::Result
Top-level callback: invoked for each Lifetime<I>
that is
encountered when visiting. By default, invokes
super_visit_with
, which will in turn invoke the more
specialized visiting methods below, like visit_free_var
.
fn visit_const(
&mut self,
constant: &Const<I>,
outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
constant: &Const<I>,
outer_binder: DebruijnIndex
) -> Self::Result
Top-level callback: invoked for each Const<I>
that is
encountered when visiting. By default, invokes
super_visit_with
, which will in turn invoke the more
specialized visiting methods below, like visit_free_var
.
fn visit_program_clause(
&mut self,
clause: &ProgramClause<I>,
outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
clause: &ProgramClause<I>,
outer_binder: DebruijnIndex
) -> Self::Result
Invoked for every program clause. By default, recursively visits the goals contents.
fn visit_goal(
&mut self,
goal: &Goal<I>,
outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
goal: &Goal<I>,
outer_binder: DebruijnIndex
) -> Self::Result
Invoked for every goal. By default, recursively visits the goals contents.
fn visit_domain_goal(
&mut self,
domain_goal: &DomainGoal<I>,
outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
domain_goal: &DomainGoal<I>,
outer_binder: DebruijnIndex
) -> Self::Result
fn forbid_free_vars(&self) -> bool
If overridden to return true, then visiting will panic if a free variable is encountered. This should be done if free type/lifetime/const variables are not expected.
fn visit_free_var(
&mut self,
bound_var: BoundVar,
outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
bound_var: BoundVar,
outer_binder: DebruijnIndex
) -> Self::Result
Invoked for BoundVar
instances that are not bound
within the type being visited over:
fn forbid_free_placeholders(&self) -> bool
If overridden to return true, we will panic when a free placeholder type/lifetime is encountered.
fn visit_free_placeholder(
&mut self,
universe: PlaceholderIndex,
_outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
universe: PlaceholderIndex,
_outer_binder: DebruijnIndex
) -> Self::Result
Invoked for each occurrence of a placeholder type; these are used when we instantiate binders universally.
fn visit_where_clause(
&mut self,
where_clause: &WhereClause<I>,
outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
where_clause: &WhereClause<I>,
outer_binder: DebruijnIndex
) -> Self::Result
fn forbid_inference_vars(&self) -> bool
If overridden to return true, inference variables will trigger panics when visited. Used when inference variables are unexpected.
fn visit_inference_var(
&mut self,
var: InferenceVar,
_outer_binder: DebruijnIndex
) -> Self::Result
&mut self,
var: InferenceVar,
_outer_binder: DebruijnIndex
) -> Self::Result
Invoked for each occurrence of a inference type; these are used when we instantiate binders universally.