Trait Visitor

Source

pub trait Visitor<'a>: Sized {
    type Result: VisitorResult = ();

Show 56 methods    // Provided methods
    fn visit_ident(&mut self, _: &'a Ident) -> Self::Result { ... }
    fn visit_foreign_mod(&mut self, nm: &'a ForeignMod) -> Self::Result { ... }
    fn visit_foreign_item(&mut self, i: &'a ForeignItem) -> Self::Result { ... }
    fn visit_item(&mut self, i: &'a Item) -> Self::Result { ... }
    fn visit_local(&mut self, l: &'a Local) -> Self::Result { ... }
    fn visit_block(&mut self, b: &'a Block) -> Self::Result { ... }
    fn visit_param(&mut self, param: &'a Param) -> Self::Result { ... }
    fn visit_arm(&mut self, a: &'a Arm) -> Self::Result { ... }
    fn visit_pat(&mut self, p: &'a Pat) -> Self::Result { ... }
    fn visit_anon_const(&mut self, c: &'a AnonConst) -> Self::Result { ... }
    fn visit_expr(&mut self, ex: &'a Expr) -> Self::Result { ... }
    fn visit_method_receiver_expr(&mut self, ex: &'a Expr) -> Self::Result { ... }
    fn visit_ty(&mut self, t: &'a Ty) -> Self::Result { ... }
    fn visit_ty_pat(&mut self, t: &'a TyPat) -> Self::Result { ... }
    fn visit_generic_param(&mut self, param: &'a GenericParam) -> Self::Result { ... }
    fn visit_generics(&mut self, g: &'a Generics) -> Self::Result { ... }
    fn visit_closure_binder(&mut self, b: &'a ClosureBinder) -> Self::Result { ... }
    fn visit_contract(&mut self, c: &'a FnContract) -> Self::Result { ... }
    fn visit_where_predicate(&mut self, p: &'a WherePredicate) -> Self::Result { ... }
    fn visit_where_predicate_kind(
        &mut self,
        k: &'a WherePredicateKind,
    ) -> Self::Result { ... }
    fn visit_fn(&mut self, fk: FnKind<'a>, _: Span, _: NodeId) -> Self::Result { ... }
    fn visit_assoc_item(
        &mut self,
        i: &'a AssocItem,
        ctxt: AssocCtxt,
    ) -> Self::Result { ... }
    fn visit_trait_ref(&mut self, t: &'a TraitRef) -> Self::Result { ... }
    fn visit_param_bound(
        &mut self,
        bounds: &'a GenericBound,
        _ctxt: BoundKind,
    ) -> Self::Result { ... }
    fn visit_precise_capturing_arg(
        &mut self,
        arg: &'a PreciseCapturingArg,
    ) -> Self::Result { ... }
    fn visit_poly_trait_ref(&mut self, t: &'a PolyTraitRef) -> Self::Result { ... }
    fn visit_variant_data(&mut self, s: &'a VariantData) -> Self::Result { ... }
    fn visit_field_def(&mut self, s: &'a FieldDef) -> Self::Result { ... }
    fn visit_variant(&mut self, v: &'a Variant) -> Self::Result { ... }
    fn visit_label(&mut self, label: &'a Label) -> Self::Result { ... }
    fn visit_lifetime(
        &mut self,
        lifetime: &'a Lifetime,
        _: LifetimeCtxt,
    ) -> Self::Result { ... }
    fn visit_mac_call(&mut self, mac: &'a MacCall) -> Self::Result { ... }
    fn visit_id(&mut self, _id: NodeId) -> Self::Result { ... }
    fn visit_macro_def(&mut self, macro_def: &'a MacroDef) -> Self::Result { ... }
    fn visit_path(&mut self, path: &'a Path) -> Self::Result { ... }
    fn visit_use_tree(&mut self, use_tree: &'a UseTree) -> Self::Result { ... }
    fn visit_path_segment(
        &mut self,
        path_segment: &'a PathSegment,
    ) -> Self::Result { ... }
    fn visit_generic_args(
        &mut self,
        generic_args: &'a GenericArgs,
    ) -> Self::Result { ... }
    fn visit_generic_arg(&mut self, generic_arg: &'a GenericArg) -> Self::Result { ... }
    fn visit_assoc_item_constraint(
        &mut self,
        constraint: &'a AssocItemConstraint,
    ) -> Self::Result { ... }
    fn visit_attribute(&mut self, attr: &'a Attribute) -> Self::Result { ... }
    fn visit_vis(&mut self, vis: &'a Visibility) -> Self::Result { ... }
    fn visit_fn_ret_ty(&mut self, ret_ty: &'a FnRetTy) -> Self::Result { ... }
    fn visit_fn_header(&mut self, header: &'a FnHeader) -> Self::Result { ... }
    fn visit_expr_field(&mut self, f: &'a ExprField) -> Self::Result { ... }
    fn visit_pat_field(&mut self, fp: &'a PatField) -> Self::Result { ... }
    fn visit_crate(&mut self, krate: &'a Crate) -> Self::Result { ... }
    fn visit_inline_asm(&mut self, asm: &'a InlineAsm) -> Self::Result { ... }
    fn visit_format_args(&mut self, fmt: &'a FormatArgs) -> Self::Result { ... }
    fn visit_inline_asm_sym(&mut self, sym: &'a InlineAsmSym) -> Self::Result { ... }
    fn visit_capture_by(&mut self, capture_by: &'a CaptureBy) -> Self::Result { ... }
    fn visit_coroutine_kind(
        &mut self,
        coroutine_kind: &'a CoroutineKind,
    ) -> Self::Result { ... }
    fn visit_fn_decl(&mut self, fn_decl: &'a FnDecl) -> Self::Result { ... }
    fn visit_qself(&mut self, qs: &'a Option<P<QSelf>>) -> Self::Result { ... }
    fn visit_stmt(&mut self, s: &'a Stmt) -> Self::Result { ... }
    fn visit_nested_use_tree(
        &mut self,
        use_tree: &'a UseTree,
        id: NodeId,
    ) -> Self::Result { ... }
}

Expand description

Each method of this trait is a hook to be potentially overridden. Each method’s default implementation recursively visits the substructure of the input via the corresponding walk method; e.g., the visit_item method by default calls visit::walk_item.

If you want to ensure that your code handles every variant explicitly, you need to override each method. (And you also need to monitor future changes to this trait in case a new method with a new default implementation gets introduced.)

Every walk_* method uses deconstruction to access fields of structs and enums. This will result in a compile error if a field is added, which makes it more likely the appropriate visit call will be added for it.