Trait rustc_type_ir::fold::TypeFoldable
source · pub trait TypeFoldable<I: Interner>: TypeVisitable<I> {
// Required method
fn try_fold_with<F: FallibleTypeFolder<I>>(
self,
folder: &mut F
) -> Result<Self, F::Error>;
// Provided method
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self { ... }
}Expand description
This trait is implemented for every type that can be folded, providing the skeleton of the traversal.
To implement this conveniently, use the derive macro located in
rustc_macros.
This trait is a sub-trait of TypeVisitable. This is because many
TypeFolder instances use the methods in TypeVisitableExt while folding,
which means in practice almost every foldable type needs to also be
visitable. (However, there are some types that are visitable without being
foldable.)
Required Methods§
sourcefn try_fold_with<F: FallibleTypeFolder<I>>(
self,
folder: &mut F
) -> Result<Self, F::Error>
fn try_fold_with<F: FallibleTypeFolder<I>>( self, folder: &mut F ) -> Result<Self, F::Error>
The entry point for folding. To fold a value t with a folder f
call: t.try_fold_with(f).
For most types, this just traverses the value, calling try_fold_with
on each field/element.
For types of interest (such as Ty), the implementation of this method
calls a folder method specifically for that type (such as
F::try_fold_ty). This is where control transfers from TypeFoldable
to TypeFolder.
Provided Methods§
sourcefn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self
fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self
A convenient alternative to try_fold_with for use with infallible
folders. Do not override this method, to ensure coherence with
try_fold_with.