Struct BindingLevel

pub(crate) struct BindingLevel {
    pub params: GenericParams,
    pub is_item_binder: bool,
    pub early_region_vars: BTreeMap<EarlyParamRegion, RegionId>,
    pub bound_region_vars: Vec<RegionId>,
    pub type_vars_map: HashMap<u32, TypeVarId>,
    pub const_generic_vars_map: HashMap<u32, ConstGenericVarId>,
    pub type_trans_cache: HashMap<HashByAddr<Arc<TyKind>>, Ty>,
}

A level of binding for type-level variables. Each item has a top-level binding level corresponding to the parameters and clauses to the items. We may then encounter inner binding levels in the following cases:

• for<..> binders in predicates;
• fn<..> function pointer types;
• dyn Trait types, represented as dyn<T: Trait> (TODO);
• types in a trait declaration or implementation block (TODO);
• methods in a trait declaration or implementation block (TODO).

At each level, we store two things: a GenericParams that contains the parameters bound at this level, and various maps from the rustc-internal indices to our indices.

Fields

params: GenericParams

The parameters and predicates bound at this level.

is_item_binder: bool

Whether this binder corresponds to an item (method, type) or not (for<..> predicate, fn pointer, etc). This indicates whether it corresponds to a rustc ParamEnv and therefore whether we should resolve rustc variables there.

early_region_vars: BTreeMap<EarlyParamRegion, RegionId>

Rust makes the distinction between early and late-bound region parameters. We do not make this distinction, and merge early and late bound regions. For details, see: https://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/ https://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/

The map from rust early regions to translated region indices.

bound_region_vars: Vec<RegionId>

The map from rust late/bound regions to translated region indices.

type_vars_map: HashMap<u32, TypeVarId>

The map from rust type variable indices to translated type variable indices.

const_generic_vars_map: HashMap<u32, ConstGenericVarId>

The map from rust const generic variables to translate const generic variable indices.

type_trans_cache: HashMap<HashByAddr<Arc<TyKind>>, Ty>

Cache the translation of types. This harnesses the deduplication of TyKind that hax does.

Implementations

impl BindingLevel

pub(crate) fn new(is_item_binder: bool) -> Self

pub(crate) fn push_early_region(&mut self, region: EarlyParamRegion) -> RegionId

Important: we must push all the early-bound regions before pushing any other region.

pub(crate) fn push_bound_region(&mut self, region: BoundRegionKind) -> RegionId

Important: we must push all the early-bound regions before pushing any other region.

pub(crate) fn push_type_var(&mut self, rid: u32, name: String) -> TypeVarId

pub(crate) fn push_const_generic_var( &mut self, rid: u32, ty: LiteralTy, name: String, )

pub(crate) fn push_params_from_binder( &mut self, binder: Binder<()>, ) -> Result<(), Error>

Translate a binder of regions by appending the stored reguions to the given vector.

Trait Implementations

impl Debug for BindingLevel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.