| // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| use middle::const_val::ConstVal; |
| use ty::subst::Substs; |
| use ty::{self, Ty, TypeFlags, TypeFoldable}; |
| |
| #[derive(Debug)] |
| pub struct FlagComputation { |
| pub flags: TypeFlags, |
| |
| // see `TyS::outer_exclusive_binder` for details |
| pub outer_exclusive_binder: ty::DebruijnIndex, |
| } |
| |
| impl FlagComputation { |
| fn new() -> FlagComputation { |
| FlagComputation { |
| flags: TypeFlags::empty(), |
| outer_exclusive_binder: ty::DebruijnIndex::INNERMOST, |
| } |
| } |
| |
| pub fn for_sty(st: &ty::TypeVariants) -> FlagComputation { |
| let mut result = FlagComputation::new(); |
| result.add_sty(st); |
| result |
| } |
| |
| fn add_flags(&mut self, flags: TypeFlags) { |
| self.flags = self.flags | (flags & TypeFlags::NOMINAL_FLAGS); |
| } |
| |
| /// indicates that `self` refers to something at binding level `binder` |
| fn add_binder(&mut self, binder: ty::DebruijnIndex) { |
| let exclusive_binder = binder.shifted_in(1); |
| self.add_exclusive_binder(exclusive_binder); |
| } |
| |
| /// indicates that `self` refers to something *inside* binding |
| /// level `binder` -- not bound by `binder`, but bound by the next |
| /// binder internal to it |
| fn add_exclusive_binder(&mut self, exclusive_binder: ty::DebruijnIndex) { |
| self.outer_exclusive_binder = self.outer_exclusive_binder.max(exclusive_binder); |
| } |
| |
| /// Adds the flags/depth from a set of types that appear within the current type, but within a |
| /// region binder. |
| fn add_bound_computation(&mut self, computation: &FlagComputation) { |
| self.add_flags(computation.flags); |
| |
| // The types that contributed to `computation` occurred within |
| // a region binder, so subtract one from the region depth |
| // within when adding the depth to `self`. |
| let outer_exclusive_binder = computation.outer_exclusive_binder; |
| if outer_exclusive_binder > ty::DebruijnIndex::INNERMOST { |
| self.add_exclusive_binder(outer_exclusive_binder.shifted_out(1)); |
| } else { |
| // otherwise, this binder captures nothing |
| } |
| } |
| |
| fn add_sty(&mut self, st: &ty::TypeVariants) { |
| match st { |
| &ty::TyBool | |
| &ty::TyChar | |
| &ty::TyInt(_) | |
| &ty::TyFloat(_) | |
| &ty::TyUint(_) | |
| &ty::TyNever | |
| &ty::TyStr | |
| &ty::TyForeign(..) => { |
| } |
| |
| // You might think that we could just return TyError for |
| // any type containing TyError as a component, and get |
| // rid of the TypeFlags::HAS_TY_ERR flag -- likewise for ty_bot (with |
| // the exception of function types that return bot). |
| // But doing so caused sporadic memory corruption, and |
| // neither I (tjc) nor nmatsakis could figure out why, |
| // so we're doing it this way. |
| &ty::TyError => { |
| self.add_flags(TypeFlags::HAS_TY_ERR) |
| } |
| |
| &ty::TyParam(ref p) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| if p.is_self() { |
| self.add_flags(TypeFlags::HAS_SELF); |
| } else { |
| self.add_flags(TypeFlags::HAS_PARAMS); |
| } |
| } |
| |
| &ty::TyGenerator(_, ref substs, _) => { |
| self.add_flags(TypeFlags::HAS_TY_CLOSURE); |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_substs(&substs.substs); |
| } |
| |
| &ty::TyGeneratorWitness(ref ts) => { |
| let mut computation = FlagComputation::new(); |
| computation.add_tys(&ts.skip_binder()[..]); |
| self.add_bound_computation(&computation); |
| } |
| |
| &ty::TyClosure(_, ref substs) => { |
| self.add_flags(TypeFlags::HAS_TY_CLOSURE); |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); |
| self.add_substs(&substs.substs); |
| } |
| |
| &ty::TyInfer(infer) => { |
| self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES); // it might, right? |
| self.add_flags(TypeFlags::HAS_TY_INFER); |
| match infer { |
| ty::FreshTy(_) | |
| ty::FreshIntTy(_) | |
| ty::FreshFloatTy(_) | |
| ty::CanonicalTy(_) => { |
| self.add_flags(TypeFlags::HAS_CANONICAL_VARS); |
| } |
| |
| ty::TyVar(_) | |
| ty::IntVar(_) | |
| ty::FloatVar(_) => { |
| self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX) |
| } |
| } |
| } |
| |
| &ty::TyAdt(_, substs) => { |
| self.add_substs(substs); |
| } |
| |
| &ty::TyProjection(ref data) => { |
| // currently we can't normalize projections that |
| // include bound regions, so track those separately. |
| if !data.has_escaping_regions() { |
| self.add_flags(TypeFlags::HAS_NORMALIZABLE_PROJECTION); |
| } |
| self.add_flags(TypeFlags::HAS_PROJECTION); |
| self.add_projection_ty(data); |
| } |
| |
| &ty::TyAnon(_, substs) => { |
| self.add_flags(TypeFlags::HAS_PROJECTION); |
| self.add_substs(substs); |
| } |
| |
| &ty::TyDynamic(ref obj, r) => { |
| let mut computation = FlagComputation::new(); |
| for predicate in obj.skip_binder().iter() { |
| match *predicate { |
| ty::ExistentialPredicate::Trait(tr) => computation.add_substs(tr.substs), |
| ty::ExistentialPredicate::Projection(p) => { |
| let mut proj_computation = FlagComputation::new(); |
| proj_computation.add_existential_projection(&p); |
| self.add_bound_computation(&proj_computation); |
| } |
| ty::ExistentialPredicate::AutoTrait(_) => {} |
| } |
| } |
| self.add_bound_computation(&computation); |
| self.add_region(r); |
| } |
| |
| &ty::TyArray(tt, len) => { |
| self.add_ty(tt); |
| self.add_const(len); |
| } |
| |
| &ty::TySlice(tt) => { |
| self.add_ty(tt) |
| } |
| |
| &ty::TyRawPtr(ref m) => { |
| self.add_ty(m.ty); |
| } |
| |
| &ty::TyRef(r, ty, _) => { |
| self.add_region(r); |
| self.add_ty(ty); |
| } |
| |
| &ty::TyTuple(ref ts) => { |
| self.add_tys(&ts[..]); |
| } |
| |
| &ty::TyFnDef(_, substs) => { |
| self.add_substs(substs); |
| } |
| |
| &ty::TyFnPtr(f) => { |
| self.add_fn_sig(f); |
| } |
| } |
| } |
| |
| fn add_ty(&mut self, ty: Ty) { |
| self.add_flags(ty.flags); |
| self.add_exclusive_binder(ty.outer_exclusive_binder); |
| } |
| |
| fn add_tys(&mut self, tys: &[Ty]) { |
| for &ty in tys { |
| self.add_ty(ty); |
| } |
| } |
| |
| fn add_fn_sig(&mut self, fn_sig: ty::PolyFnSig) { |
| let mut computation = FlagComputation::new(); |
| |
| computation.add_tys(fn_sig.skip_binder().inputs()); |
| computation.add_ty(fn_sig.skip_binder().output()); |
| |
| self.add_bound_computation(&computation); |
| } |
| |
| fn add_region(&mut self, r: ty::Region) { |
| self.add_flags(r.type_flags()); |
| if let ty::ReLateBound(debruijn, _) = *r { |
| self.add_binder(debruijn); |
| } |
| } |
| |
| fn add_const(&mut self, constant: &ty::Const) { |
| self.add_ty(constant.ty); |
| match constant.val { |
| ConstVal::Value(_) => {} |
| ConstVal::Unevaluated(_, substs) => { |
| self.add_flags(TypeFlags::HAS_PROJECTION); |
| self.add_substs(substs); |
| } |
| } |
| } |
| |
| fn add_existential_projection(&mut self, projection: &ty::ExistentialProjection) { |
| self.add_substs(projection.substs); |
| self.add_ty(projection.ty); |
| } |
| |
| fn add_projection_ty(&mut self, projection_ty: &ty::ProjectionTy) { |
| self.add_substs(projection_ty.substs); |
| } |
| |
| fn add_substs(&mut self, substs: &Substs) { |
| for ty in substs.types() { |
| self.add_ty(ty); |
| } |
| |
| for r in substs.regions() { |
| self.add_region(r); |
| } |
| } |
| } |
