Trait TypeFolder

pub trait TypeFolder<I>: FallibleTypeFolder<I, Error = !>
where
    I: Interner,
{
    // Required method
    fn cx(&self) -> I;

    // Provided methods
    fn fold_binder<T>(&mut self, t: Binder<I, T>) -> Binder<I, T>
       where T: TypeFoldable<I> { ... }
    fn fold_ty(&mut self, t: <I as Interner>::Ty) -> <I as Interner>::Ty { ... }
    fn fold_region(
        &mut self,
        r: <I as Interner>::Region,
    ) -> <I as Interner>::Region { ... }
    fn fold_const(
        &mut self,
        c: <I as Interner>::Const,
    ) -> <I as Interner>::Const { ... }
    fn fold_predicate(
        &mut self,
        p: <I as Interner>::Predicate,
    ) -> <I as Interner>::Predicate { ... }
}

This trait is implemented for every infallible folding traversal. There is a fold method defined for every type of interest. Each such method has a default that does an “identity” fold. Implementations of these methods often fall back to a super_fold_with method if the primary argument doesn’t satisfy a particular condition.

A blanket implementation of FallibleTypeFolder will defer to the infallible methods of this trait to ensure that the two APIs are coherent.

Required Methods

fn cx(&self) -> I

Provided Methods

fn fold_binder<T>(&mut self, t: Binder<I, T>) -> Binder<I, T>

where T: TypeFoldable<I>,

fn fold_ty(&mut self, t: <I as Interner>::Ty) -> <I as Interner>::Ty

fn fold_region(&mut self, r: <I as Interner>::Region) -> <I as Interner>::Region

fn fold_const(&mut self, c: <I as Interner>::Const) -> <I as Interner>::Const

fn fold_predicate( &mut self, p: <I as Interner>::Predicate, ) -> <I as Interner>::Predicate

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for rustc_middle::ty::print::pretty::RegionFolder<'a, 'tcx>

impl<'a, I> TypeFolder<I> for rustc_type_ir::fold::RegionFolder<'a, I>

where I: Interner,

impl<'tcx> TypeFolder<TyCtxt<'tcx>> for RegionEraserVisitor<'tcx>

impl<'tcx> TypeFolder<TyCtxt<'tcx>> for NormalizeAfterErasingRegionsFolder<'tcx>

impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReverseMapper<'tcx>

impl<'tcx> TypeFolder<TyCtxt<'tcx>> for OpaqueTypeExpander<'tcx>

impl<'tcx> TypeFolder<TyCtxt<'tcx>> for WeakAliasTypeExpander<'tcx>

impl<'tcx, D> TypeFolder<TyCtxt<'tcx>> for BoundVarReplacer<'tcx, D>

where D: BoundVarReplacerDelegate<'tcx>,

impl<'tcx, F, G, H> TypeFolder<TyCtxt<'tcx>> for BottomUpFolder<'tcx, F, G, H>

where F: FnMut(Ty<'tcx>) -> Ty<'tcx>, G: FnMut(Region<'tcx>) -> Region<'tcx>, H: FnMut(Const<'tcx>) -> Const<'tcx>,