Trait rustc_const_eval::interpret::visitor::ValueVisitor

source · 
pub trait ValueVisitor<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>: Sized {
    type V: Value<'mir, 'tcx, M>;

    fn ecx(&self) -> &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§

The visitor must have an InterpCx in it.

Provided Methods§

read_discriminant can be hooked for better error messages.

Visits the given value, dispatching as appropriate to more specialized visitors.

Visits the given value as a union. No automatic recursion can happen here.

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.

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.

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.

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.

Implementors§