Trait rustc_const_eval::interpret::visitor::MutValueVisitor
source · pub trait MutValueVisitor<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>: Sized {
type V: ValueMut<'mir, 'tcx, M>;
fn ecx(&mut self) -> &mut InterpCx<'mir, 'tcx, M>;
fn read_discriminant(
&mut self,
op: &OpTy<'tcx, M::Provenance>
) -> InterpResult<'tcx, VariantIdx> { ... }
fn visit_value(&mut self, v: &Self::V) -> InterpResult<'tcx> { ... }
fn visit_union(
&mut self,
_v: &Self::V,
_fields: NonZeroUsize
) -> InterpResult<'tcx> { ... }
fn visit_box(&mut self, _v: &Self::V) -> InterpResult<'tcx> { ... }
fn visit_aggregate(
&mut self,
v: &Self::V,
fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>
) -> InterpResult<'tcx> { ... }
fn visit_field(
&mut self,
_old_val: &Self::V,
_field: usize,
new_val: &Self::V
) -> InterpResult<'tcx> { ... }
fn visit_variant(
&mut self,
_old_val: &Self::V,
_variant: VariantIdx,
new_val: &Self::V
) -> InterpResult<'tcx> { ... }
fn walk_aggregate(
&mut self,
v: &Self::V,
fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>
) -> InterpResult<'tcx> { ... }
fn walk_value(&mut self, v: &Self::V) -> InterpResult<'tcx> { ... }
}
Expand description
How to traverse a value and what to do when we are at the leaves.
Required Associated Types§
Required Methods§
Provided Methods§
sourcefn read_discriminant(
&mut self,
op: &OpTy<'tcx, M::Provenance>
) -> InterpResult<'tcx, VariantIdx>
fn read_discriminant(
&mut self,
op: &OpTy<'tcx, M::Provenance>
) -> InterpResult<'tcx, VariantIdx>
read_discriminant
can be hooked for better error messages.
sourcefn visit_value(&mut self, v: &Self::V) -> InterpResult<'tcx>
fn visit_value(&mut self, v: &Self::V) -> InterpResult<'tcx>
Visits the given value, dispatching as appropriate to more specialized visitors.
sourcefn visit_union(
&mut self,
_v: &Self::V,
_fields: NonZeroUsize
) -> InterpResult<'tcx>
fn visit_union(
&mut self,
_v: &Self::V,
_fields: NonZeroUsize
) -> InterpResult<'tcx>
Visits the given value as a union. No automatic recursion can happen here.
sourcefn visit_box(&mut self, _v: &Self::V) -> InterpResult<'tcx>
fn visit_box(&mut self, _v: &Self::V) -> InterpResult<'tcx>
Visits the given value as the pointer of a Box
. There is nothing to recurse into.
The type of v
will be a raw pointer, but this is a field of Box<T>
and the
pointee type is the actual T
.
sourcefn visit_aggregate(
&mut self,
v: &Self::V,
fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>
) -> InterpResult<'tcx>
fn visit_aggregate(
&mut self,
v: &Self::V,
fields: impl Iterator<Item = InterpResult<'tcx, Self::V>>
) -> InterpResult<'tcx>
Visits this value as an aggregate, you are getting an iterator yielding
all the fields (still in an InterpResult
, you have to do error handling yourself).
Recurses into the fields.
sourcefn visit_field(
&mut self,
_old_val: &Self::V,
_field: usize,
new_val: &Self::V
) -> InterpResult<'tcx>
fn visit_field(
&mut self,
_old_val: &Self::V,
_field: usize,
new_val: &Self::V
) -> InterpResult<'tcx>
Called each time we recurse down to a field of a “product-like” aggregate (structs, tuples, arrays and the like, but not enums), passing in old (outer) and new (inner) value. This gives the visitor the chance to track the stack of nested fields that we are descending through.
sourcefn visit_variant(
&mut self,
_old_val: &Self::V,
_variant: VariantIdx,
new_val: &Self::V
) -> InterpResult<'tcx>
fn visit_variant(
&mut self,
_old_val: &Self::V,
_variant: VariantIdx,
new_val: &Self::V
) -> InterpResult<'tcx>
Called when recursing into an enum variant. This gives the visitor the chance to track the stack of nested fields that we are descending through.