875 lines
30 KiB
Rust
875 lines
30 KiB
Rust
// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Generalized type folding mechanism. The setup is a bit convoluted
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//! but allows for convenient usage. Let T be an instance of some
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//! "foldable type" (one which implements `TypeFoldable`) and F be an
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//! instance of a "folder" (a type which implements `TypeFolder`). Then
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//! the setup is intended to be:
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//!
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//! T.fold_with(F) --calls--> F.fold_T(T) --calls--> super_fold_T(F, T)
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//!
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//! This way, when you define a new folder F, you can override
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//! `fold_T()` to customize the behavior, and invoke `super_fold_T()`
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//! to get the original behavior. Meanwhile, to actually fold
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//! something, you can just write `T.fold_with(F)`, which is
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//! convenient. (Note that `fold_with` will also transparently handle
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//! things like a `Vec<T>` where T is foldable and so on.)
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//!
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//! In this ideal setup, the only function that actually *does*
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//! anything is `super_fold_T`, which traverses the type `T`. Moreover,
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//! `super_fold_T` should only ever call `T.fold_with()`.
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//!
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//! In some cases, we follow a degenerate pattern where we do not have
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//! a `fold_T` nor `super_fold_T` method. Instead, `T.fold_with`
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//! traverses the structure directly. This is suboptimal because the
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//! behavior cannot be overriden, but it's much less work to implement.
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//! If you ever *do* need an override that doesn't exist, it's not hard
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//! to convert the degenerate pattern into the proper thing.
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use middle::subst;
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use middle::subst::VecPerParamSpace;
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use middle::ty::{mod, Ty};
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use middle::traits;
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use std::rc::Rc;
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use syntax::owned_slice::OwnedSlice;
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use util::ppaux::Repr;
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///////////////////////////////////////////////////////////////////////////
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// Two generic traits
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/// The TypeFoldable trait is implemented for every type that can be folded.
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/// Basically, every type that has a corresponding method in TypeFolder.
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pub trait TypeFoldable<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self;
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}
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/// The TypeFolder trait defines the actual *folding*. There is a
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/// method defined for every foldable type. Each of these has a
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/// default implementation that does an "identity" fold. Within each
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/// identity fold, it should invoke `foo.fold_with(self)` to fold each
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/// sub-item.
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pub trait TypeFolder<'tcx> {
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fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx>;
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/// Invoked by the `super_*` routines when we enter a region
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/// binding level (for example, when entering a function
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/// signature). This is used by clients that want to track the
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/// Debruijn index nesting level.
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fn enter_region_binder(&mut self) { }
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/// Invoked by the `super_*` routines when we exit a region
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/// binding level. This is used by clients that want to
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/// track the Debruijn index nesting level.
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fn exit_region_binder(&mut self) { }
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fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
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super_fold_ty(self, t)
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}
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fn fold_mt(&mut self, t: &ty::mt<'tcx>) -> ty::mt<'tcx> {
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super_fold_mt(self, t)
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}
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fn fold_trait_ref(&mut self, t: &ty::TraitRef<'tcx>) -> ty::TraitRef<'tcx> {
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super_fold_trait_ref(self, t)
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}
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fn fold_sty(&mut self, sty: &ty::sty<'tcx>) -> ty::sty<'tcx> {
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super_fold_sty(self, sty)
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}
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fn fold_substs(&mut self,
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substs: &subst::Substs<'tcx>)
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-> subst::Substs<'tcx> {
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super_fold_substs(self, substs)
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}
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fn fold_fn_sig(&mut self,
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sig: &ty::FnSig<'tcx>)
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-> ty::FnSig<'tcx> {
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super_fold_fn_sig(self, sig)
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}
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fn fold_output(&mut self,
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output: &ty::FnOutput<'tcx>)
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-> ty::FnOutput<'tcx> {
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super_fold_output(self, output)
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}
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fn fold_bare_fn_ty(&mut self,
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fty: &ty::BareFnTy<'tcx>)
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-> ty::BareFnTy<'tcx>
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{
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super_fold_bare_fn_ty(self, fty)
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}
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fn fold_closure_ty(&mut self,
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fty: &ty::ClosureTy<'tcx>)
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-> ty::ClosureTy<'tcx> {
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super_fold_closure_ty(self, fty)
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}
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fn fold_region(&mut self, r: ty::Region) -> ty::Region {
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r
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}
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fn fold_trait_store(&mut self, s: ty::TraitStore) -> ty::TraitStore {
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super_fold_trait_store(self, s)
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}
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fn fold_existential_bounds(&mut self, s: ty::ExistentialBounds)
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-> ty::ExistentialBounds {
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super_fold_existential_bounds(self, s)
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}
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fn fold_autoref(&mut self, ar: &ty::AutoRef<'tcx>) -> ty::AutoRef<'tcx> {
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super_fold_autoref(self, ar)
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}
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fn fold_item_substs(&mut self, i: ty::ItemSubsts<'tcx>) -> ty::ItemSubsts<'tcx> {
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super_fold_item_substs(self, i)
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}
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}
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///////////////////////////////////////////////////////////////////////////
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// TypeFoldable implementations.
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//
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// Ideally, each type should invoke `folder.fold_foo(self)` and
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// nothing else. In some cases, though, we haven't gotten around to
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// adding methods on the `folder` yet, and thus the folding is
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// hard-coded here. This is less-flexible, because folders cannot
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// override the behavior, but there are a lot of random types and one
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// can easily refactor the folding into the TypeFolder trait as
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// needed.
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impl<'tcx> TypeFoldable<'tcx> for () {
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fn fold_with<F:TypeFolder<'tcx>>(&self, _: &mut F) -> () {
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()
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}
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}
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impl<'tcx, T:TypeFoldable<'tcx>, U:TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
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fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> (T, U) {
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(self.0.fold_with(folder), self.1.fold_with(folder))
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}
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}
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impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Option<T> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Option<T> {
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self.as_ref().map(|t| t.fold_with(folder))
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}
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}
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impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Rc<T> {
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Rc::new((**self).fold_with(folder))
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}
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}
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impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Vec<T> {
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self.iter().map(|t| t.fold_with(folder)).collect()
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}
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}
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impl<'tcx, T:TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<T> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::Binder<T> {
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folder.enter_region_binder();
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let result = ty::bind(self.value.fold_with(folder));
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folder.exit_region_binder();
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result
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}
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}
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impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for OwnedSlice<T> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> OwnedSlice<T> {
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self.iter().map(|t| t.fold_with(folder)).collect()
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}
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}
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impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for VecPerParamSpace<T> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> VecPerParamSpace<T> {
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// Things in the Fn space take place under an additional level
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// of region binding relative to the other spaces. This is
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// because those entries are attached to a method, and methods
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// always introduce a level of region binding.
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let result = self.map_enumerated(|(space, index, elem)| {
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if space == subst::FnSpace && index == 0 {
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// enter new level when/if we reach the first thing in fn space
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folder.enter_region_binder();
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}
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elem.fold_with(folder)
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});
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if result.len(subst::FnSpace) > 0 {
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// if there was anything in fn space, exit the region binding level
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folder.exit_region_binder();
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}
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result
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::TraitStore {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::TraitStore {
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folder.fold_trait_store(*self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Ty<'tcx> {
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folder.fold_ty(*self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::BareFnTy<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::BareFnTy<'tcx> {
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folder.fold_bare_fn_ty(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::ClosureTy<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::ClosureTy<'tcx> {
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folder.fold_closure_ty(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::mt<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::mt<'tcx> {
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folder.fold_mt(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::FnOutput<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::FnOutput<'tcx> {
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folder.fold_output(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::FnSig<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::FnSig<'tcx> {
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folder.fold_fn_sig(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::sty<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::sty<'tcx> {
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folder.fold_sty(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::TraitRef<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::TraitRef<'tcx> {
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folder.fold_trait_ref(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::Region {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::Region {
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folder.fold_region(*self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for subst::Substs<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> subst::Substs<'tcx> {
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folder.fold_substs(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::ItemSubsts<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::ItemSubsts<'tcx> {
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ty::ItemSubsts {
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substs: self.substs.fold_with(folder),
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::AutoRef<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::AutoRef<'tcx> {
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folder.fold_autoref(self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::MethodOrigin<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::MethodOrigin<'tcx> {
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match *self {
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ty::MethodStatic(def_id) => {
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ty::MethodStatic(def_id)
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}
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ty::MethodStaticUnboxedClosure(def_id) => {
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ty::MethodStaticUnboxedClosure(def_id)
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}
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ty::MethodTypeParam(ref param) => {
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ty::MethodTypeParam(ty::MethodParam {
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trait_ref: param.trait_ref.fold_with(folder),
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method_num: param.method_num
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})
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}
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ty::MethodTraitObject(ref object) => {
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ty::MethodTraitObject(ty::MethodObject {
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trait_ref: object.trait_ref.fold_with(folder),
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object_trait_id: object.object_trait_id,
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method_num: object.method_num,
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real_index: object.real_index
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})
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}
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::vtable_origin<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::vtable_origin<'tcx> {
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match *self {
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ty::vtable_static(def_id, ref substs, ref origins) => {
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let r_substs = substs.fold_with(folder);
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let r_origins = origins.fold_with(folder);
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ty::vtable_static(def_id, r_substs, r_origins)
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}
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ty::vtable_param(n, b) => {
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ty::vtable_param(n, b)
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}
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ty::vtable_unboxed_closure(def_id) => {
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ty::vtable_unboxed_closure(def_id)
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}
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ty::vtable_error => {
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ty::vtable_error
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}
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::BuiltinBounds {
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fn fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> ty::BuiltinBounds {
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*self
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::ExistentialBounds {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::ExistentialBounds {
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folder.fold_existential_bounds(*self)
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::ParamBounds<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::ParamBounds<'tcx> {
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ty::ParamBounds {
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region_bounds: self.region_bounds.fold_with(folder),
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builtin_bounds: self.builtin_bounds.fold_with(folder),
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trait_bounds: self.trait_bounds.fold_with(folder),
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::TypeParameterDef<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::TypeParameterDef<'tcx> {
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ty::TypeParameterDef {
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name: self.name,
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def_id: self.def_id,
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space: self.space,
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index: self.index,
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associated_with: self.associated_with,
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bounds: self.bounds.fold_with(folder),
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default: self.default.fold_with(folder),
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::RegionParameterDef {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::RegionParameterDef {
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ty::RegionParameterDef {
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name: self.name,
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def_id: self.def_id,
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space: self.space,
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index: self.index,
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bounds: self.bounds.fold_with(folder)
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::Generics<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::Generics<'tcx> {
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ty::Generics {
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types: self.types.fold_with(folder),
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regions: self.regions.fold_with(folder),
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predicates: self.predicates.fold_with(folder),
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::Predicate<'tcx> {
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match *self {
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ty::Predicate::Trait(ref a) =>
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ty::Predicate::Trait(a.fold_with(folder)),
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ty::Predicate::Equate(ref a, ref b) =>
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ty::Predicate::Equate(a.fold_with(folder),
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b.fold_with(folder)),
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ty::Predicate::RegionOutlives(ref a, ref b) =>
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ty::Predicate::RegionOutlives(a.fold_with(folder),
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b.fold_with(folder)),
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ty::Predicate::TypeOutlives(ref a, ref b) =>
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ty::Predicate::TypeOutlives(a.fold_with(folder),
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b.fold_with(folder)),
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::GenericBounds<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::GenericBounds<'tcx> {
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ty::GenericBounds {
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types: self.types.fold_with(folder),
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regions: self.regions.fold_with(folder),
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}
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}
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}
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impl<'tcx> TypeFoldable<'tcx> for ty::UnsizeKind<'tcx> {
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fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::UnsizeKind<'tcx> {
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match *self {
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ty::UnsizeLength(len) => ty::UnsizeLength(len),
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ty::UnsizeStruct(box ref k, n) => ty::UnsizeStruct(box k.fold_with(folder), n),
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ty::UnsizeVtable(ty::TyTrait{ref principal, bounds}, self_ty) => {
|
|
ty::UnsizeVtable(
|
|
ty::TyTrait {
|
|
principal: principal.fold_with(folder),
|
|
bounds: bounds.fold_with(folder),
|
|
},
|
|
self_ty.fold_with(folder))
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx,O> TypeFoldable<'tcx> for traits::Obligation<'tcx,O>
|
|
where O : TypeFoldable<'tcx>
|
|
{
|
|
fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::Obligation<'tcx, O> {
|
|
traits::Obligation {
|
|
cause: self.cause,
|
|
recursion_depth: self.recursion_depth,
|
|
trait_ref: self.trait_ref.fold_with(folder),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx, N: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::VtableImplData<'tcx, N> {
|
|
fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::VtableImplData<'tcx, N> {
|
|
traits::VtableImplData {
|
|
impl_def_id: self.impl_def_id,
|
|
substs: self.substs.fold_with(folder),
|
|
nested: self.nested.fold_with(folder),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx, N: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::VtableBuiltinData<N> {
|
|
fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::VtableBuiltinData<N> {
|
|
traits::VtableBuiltinData {
|
|
nested: self.nested.fold_with(folder),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx, N: TypeFoldable<'tcx>> TypeFoldable<'tcx> for traits::Vtable<'tcx, N> {
|
|
fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::Vtable<'tcx, N> {
|
|
match *self {
|
|
traits::VtableImpl(ref v) => traits::VtableImpl(v.fold_with(folder)),
|
|
traits::VtableUnboxedClosure(d, ref s) => {
|
|
traits::VtableUnboxedClosure(d, s.fold_with(folder))
|
|
}
|
|
traits::VtableFnPointer(ref d) => {
|
|
traits::VtableFnPointer(d.fold_with(folder))
|
|
}
|
|
traits::VtableParam(ref p) => traits::VtableParam(p.fold_with(folder)),
|
|
traits::VtableBuiltin(ref d) => traits::VtableBuiltin(d.fold_with(folder)),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'tcx> TypeFoldable<'tcx> for traits::VtableParamData<'tcx> {
|
|
fn fold_with<F:TypeFolder<'tcx>>(&self, folder: &mut F) -> traits::VtableParamData<'tcx> {
|
|
traits::VtableParamData {
|
|
bound: self.bound.fold_with(folder),
|
|
}
|
|
}
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// "super" routines: these are the default implementations for TypeFolder.
|
|
//
|
|
// They should invoke `foo.fold_with()` to do recursive folding.
|
|
|
|
pub fn super_fold_ty<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
t: Ty<'tcx>)
|
|
-> Ty<'tcx> {
|
|
let sty = t.sty.fold_with(this);
|
|
ty::mk_t(this.tcx(), sty)
|
|
}
|
|
|
|
pub fn super_fold_substs<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
substs: &subst::Substs<'tcx>)
|
|
-> subst::Substs<'tcx> {
|
|
let regions = match substs.regions {
|
|
subst::ErasedRegions => {
|
|
subst::ErasedRegions
|
|
}
|
|
subst::NonerasedRegions(ref regions) => {
|
|
subst::NonerasedRegions(regions.fold_with(this))
|
|
}
|
|
};
|
|
|
|
subst::Substs { regions: regions,
|
|
types: substs.types.fold_with(this) }
|
|
}
|
|
|
|
pub fn super_fold_fn_sig<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
sig: &ty::FnSig<'tcx>)
|
|
-> ty::FnSig<'tcx>
|
|
{
|
|
this.enter_region_binder();
|
|
let result = super_fold_fn_sig_contents(this, sig);
|
|
this.exit_region_binder();
|
|
result
|
|
}
|
|
|
|
pub fn super_fold_fn_sig_contents<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
sig: &ty::FnSig<'tcx>)
|
|
-> ty::FnSig<'tcx>
|
|
{
|
|
ty::FnSig { inputs: sig.inputs.fold_with(this),
|
|
output: sig.output.fold_with(this),
|
|
variadic: sig.variadic }
|
|
}
|
|
|
|
pub fn super_fold_output<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
output: &ty::FnOutput<'tcx>)
|
|
-> ty::FnOutput<'tcx> {
|
|
match *output {
|
|
ty::FnConverging(ref ty) => ty::FnConverging(ty.fold_with(this)),
|
|
ty::FnDiverging => ty::FnDiverging
|
|
}
|
|
}
|
|
|
|
pub fn super_fold_bare_fn_ty<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
fty: &ty::BareFnTy<'tcx>)
|
|
-> ty::BareFnTy<'tcx>
|
|
{
|
|
ty::BareFnTy { sig: fty.sig.fold_with(this),
|
|
abi: fty.abi,
|
|
fn_style: fty.fn_style }
|
|
}
|
|
|
|
pub fn super_fold_closure_ty<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
fty: &ty::ClosureTy<'tcx>)
|
|
-> ty::ClosureTy<'tcx>
|
|
{
|
|
ty::ClosureTy {
|
|
store: fty.store.fold_with(this),
|
|
sig: fty.sig.fold_with(this),
|
|
fn_style: fty.fn_style,
|
|
onceness: fty.onceness,
|
|
bounds: fty.bounds.fold_with(this),
|
|
abi: fty.abi,
|
|
}
|
|
}
|
|
|
|
pub fn super_fold_trait_ref<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
t: &ty::TraitRef<'tcx>)
|
|
-> ty::TraitRef<'tcx>
|
|
{
|
|
this.enter_region_binder();
|
|
let result = super_fold_trait_ref_contents(this, t);
|
|
this.exit_region_binder();
|
|
result
|
|
}
|
|
|
|
pub fn super_fold_trait_ref_contents<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
t: &ty::TraitRef<'tcx>)
|
|
-> ty::TraitRef<'tcx>
|
|
{
|
|
ty::TraitRef {
|
|
def_id: t.def_id,
|
|
substs: t.substs.fold_with(this),
|
|
}
|
|
}
|
|
|
|
pub fn super_fold_mt<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
mt: &ty::mt<'tcx>)
|
|
-> ty::mt<'tcx> {
|
|
ty::mt {ty: mt.ty.fold_with(this),
|
|
mutbl: mt.mutbl}
|
|
}
|
|
|
|
pub fn super_fold_sty<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
sty: &ty::sty<'tcx>)
|
|
-> ty::sty<'tcx> {
|
|
match *sty {
|
|
ty::ty_uniq(typ) => {
|
|
ty::ty_uniq(typ.fold_with(this))
|
|
}
|
|
ty::ty_ptr(ref tm) => {
|
|
ty::ty_ptr(tm.fold_with(this))
|
|
}
|
|
ty::ty_vec(typ, sz) => {
|
|
ty::ty_vec(typ.fold_with(this), sz)
|
|
}
|
|
ty::ty_open(typ) => {
|
|
ty::ty_open(typ.fold_with(this))
|
|
}
|
|
ty::ty_enum(tid, ref substs) => {
|
|
ty::ty_enum(tid, substs.fold_with(this))
|
|
}
|
|
ty::ty_trait(box ty::TyTrait { ref principal, bounds }) => {
|
|
ty::ty_trait(box ty::TyTrait {
|
|
principal: (*principal).fold_with(this),
|
|
bounds: bounds.fold_with(this),
|
|
})
|
|
}
|
|
ty::ty_tup(ref ts) => {
|
|
ty::ty_tup(ts.fold_with(this))
|
|
}
|
|
ty::ty_bare_fn(ref f) => {
|
|
ty::ty_bare_fn(f.fold_with(this))
|
|
}
|
|
ty::ty_closure(ref f) => {
|
|
ty::ty_closure(box f.fold_with(this))
|
|
}
|
|
ty::ty_rptr(r, ref tm) => {
|
|
ty::ty_rptr(r.fold_with(this), tm.fold_with(this))
|
|
}
|
|
ty::ty_struct(did, ref substs) => {
|
|
ty::ty_struct(did, substs.fold_with(this))
|
|
}
|
|
ty::ty_unboxed_closure(did, ref region, ref substs) => {
|
|
ty::ty_unboxed_closure(did, region.fold_with(this), substs.fold_with(this))
|
|
}
|
|
ty::ty_bool | ty::ty_char | ty::ty_str |
|
|
ty::ty_int(_) | ty::ty_uint(_) | ty::ty_float(_) |
|
|
ty::ty_err | ty::ty_infer(_) |
|
|
ty::ty_param(..) => {
|
|
(*sty).clone()
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn super_fold_trait_store<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
trait_store: ty::TraitStore)
|
|
-> ty::TraitStore {
|
|
match trait_store {
|
|
ty::UniqTraitStore => ty::UniqTraitStore,
|
|
ty::RegionTraitStore(r, m) => {
|
|
ty::RegionTraitStore(r.fold_with(this), m)
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn super_fold_existential_bounds<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
bounds: ty::ExistentialBounds)
|
|
-> ty::ExistentialBounds {
|
|
ty::ExistentialBounds {
|
|
region_bound: bounds.region_bound.fold_with(this),
|
|
builtin_bounds: bounds.builtin_bounds,
|
|
}
|
|
}
|
|
|
|
pub fn super_fold_autoref<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
autoref: &ty::AutoRef<'tcx>)
|
|
-> ty::AutoRef<'tcx>
|
|
{
|
|
match *autoref {
|
|
ty::AutoPtr(r, m, None) => ty::AutoPtr(this.fold_region(r), m, None),
|
|
ty::AutoPtr(r, m, Some(ref a)) => {
|
|
ty::AutoPtr(this.fold_region(r), m, Some(box super_fold_autoref(this, &**a)))
|
|
}
|
|
ty::AutoUnsafe(m, None) => ty::AutoUnsafe(m, None),
|
|
ty::AutoUnsafe(m, Some(ref a)) => {
|
|
ty::AutoUnsafe(m, Some(box super_fold_autoref(this, &**a)))
|
|
}
|
|
ty::AutoUnsize(ref k) => ty::AutoUnsize(k.fold_with(this)),
|
|
ty::AutoUnsizeUniq(ref k) => ty::AutoUnsizeUniq(k.fold_with(this)),
|
|
}
|
|
}
|
|
|
|
pub fn super_fold_item_substs<'tcx, T: TypeFolder<'tcx>>(this: &mut T,
|
|
substs: ty::ItemSubsts<'tcx>)
|
|
-> ty::ItemSubsts<'tcx>
|
|
{
|
|
ty::ItemSubsts {
|
|
substs: substs.substs.fold_with(this),
|
|
}
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// Higher-ranked things
|
|
|
|
/// Designates a "binder" for late-bound regions.
|
|
pub trait HigherRankedFoldable<'tcx>: Repr<'tcx> {
|
|
/// Folds the contents of `self`, ignoring the region binder created
|
|
/// by `self`.
|
|
fn fold_contents<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self;
|
|
}
|
|
|
|
impl<'tcx> HigherRankedFoldable<'tcx> for ty::FnSig<'tcx> {
|
|
fn fold_contents<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::FnSig<'tcx> {
|
|
super_fold_fn_sig_contents(folder, self)
|
|
}
|
|
}
|
|
|
|
impl<'tcx> HigherRankedFoldable<'tcx> for ty::TraitRef<'tcx> {
|
|
fn fold_contents<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::TraitRef<'tcx> {
|
|
super_fold_trait_ref_contents(folder, self)
|
|
}
|
|
}
|
|
|
|
impl<'tcx, T:TypeFoldable<'tcx>+Repr<'tcx>> HigherRankedFoldable<'tcx> for ty::Binder<T> {
|
|
fn fold_contents<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> ty::Binder<T> {
|
|
ty::bind(self.value.fold_with(folder))
|
|
}
|
|
}
|
|
|
|
impl<'tcx, T:HigherRankedFoldable<'tcx>> HigherRankedFoldable<'tcx> for Rc<T> {
|
|
fn fold_contents<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Rc<T> {
|
|
Rc::new((**self).fold_contents(folder))
|
|
}
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// Some sample folders
|
|
|
|
pub struct BottomUpFolder<'a, 'tcx: 'a> {
|
|
pub tcx: &'a ty::ctxt<'tcx>,
|
|
pub fldop: |Ty<'tcx>|: 'a -> Ty<'tcx>,
|
|
}
|
|
|
|
impl<'a, 'tcx> TypeFolder<'tcx> for BottomUpFolder<'a, 'tcx> {
|
|
fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> { self.tcx }
|
|
|
|
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
|
|
let t1 = super_fold_ty(self, ty);
|
|
(self.fldop)(t1)
|
|
}
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// Region folder
|
|
|
|
/// Folds over the substructure of a type, visiting its component
|
|
/// types and all regions that occur *free* within it.
|
|
///
|
|
/// That is, `Ty` can contain function or method types that bind
|
|
/// regions at the call site (`ReLateBound`), and occurrences of
|
|
/// regions (aka "lifetimes") that are bound within a type are not
|
|
/// visited by this folder; only regions that occur free will be
|
|
/// visited by `fld_r`.
|
|
///
|
|
/// (The distinction between "free" and "bound" is represented by
|
|
/// keeping track of each `FnSig` in the lexical context of the
|
|
/// current position of the fold.)
|
|
pub struct RegionFolder<'a, 'tcx: 'a> {
|
|
tcx: &'a ty::ctxt<'tcx>,
|
|
current_depth: uint,
|
|
fld_r: |ty::Region, uint|: 'a -> ty::Region,
|
|
}
|
|
|
|
impl<'a, 'tcx> RegionFolder<'a, 'tcx> {
|
|
pub fn new(tcx: &'a ty::ctxt<'tcx>, fld_r: |ty::Region, uint|: 'a -> ty::Region)
|
|
-> RegionFolder<'a, 'tcx> {
|
|
RegionFolder {
|
|
tcx: tcx,
|
|
current_depth: 1,
|
|
fld_r: fld_r,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
|
|
fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> { self.tcx }
|
|
|
|
fn enter_region_binder(&mut self) {
|
|
self.current_depth += 1;
|
|
}
|
|
|
|
fn exit_region_binder(&mut self) {
|
|
self.current_depth -= 1;
|
|
}
|
|
|
|
fn fold_region(&mut self, r: ty::Region) -> ty::Region {
|
|
match r {
|
|
ty::ReLateBound(debruijn, _) if debruijn.depth < self.current_depth => {
|
|
debug!("RegionFolder.fold_region({}) skipped bound region (current depth={})",
|
|
r.repr(self.tcx()), self.current_depth);
|
|
r
|
|
}
|
|
_ => {
|
|
debug!("RegionFolder.fold_region({}) folding free region (current_depth={})",
|
|
r.repr(self.tcx()), self.current_depth);
|
|
(self.fld_r)(r, self.current_depth)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// Region eraser
|
|
//
|
|
// Replaces all free regions with 'static. Useful in trans.
|
|
|
|
pub struct RegionEraser<'a, 'tcx: 'a> {
|
|
tcx: &'a ty::ctxt<'tcx>,
|
|
}
|
|
|
|
pub fn erase_regions<'tcx, T: TypeFoldable<'tcx>>(tcx: &ty::ctxt<'tcx>, t: T) -> T {
|
|
let mut eraser = RegionEraser { tcx: tcx };
|
|
t.fold_with(&mut eraser)
|
|
}
|
|
|
|
impl<'a, 'tcx> TypeFolder<'tcx> for RegionEraser<'a, 'tcx> {
|
|
fn tcx<'a>(&'a self) -> &'a ty::ctxt<'tcx> { self.tcx }
|
|
|
|
fn fold_region(&mut self, r: ty::Region) -> ty::Region {
|
|
match r {
|
|
ty::ReLateBound(..) | ty::ReEarlyBound(..) => r,
|
|
_ => ty::ReStatic
|
|
}
|
|
}
|
|
}
|
|
|
|
///////////////////////////////////////////////////////////////////////////
|
|
// Region shifter
|
|
//
|
|
// Shifts the De Bruijn indices on all escaping bound regions by a
|
|
// fixed amount. Useful in substitution or when otherwise introducing
|
|
// a binding level that is not intended to capture the existing bound
|
|
// regions. See comment on `shift_regions_through_binders` method in
|
|
// `subst.rs` for more details.
|
|
|
|
pub fn shift_region(region: ty::Region, amount: uint) -> ty::Region {
|
|
match region {
|
|
ty::ReLateBound(debruijn, br) => {
|
|
ty::ReLateBound(debruijn.shifted(amount), br)
|
|
}
|
|
_ => {
|
|
region
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn shift_regions<'tcx, T:TypeFoldable<'tcx>+Repr<'tcx>>(tcx: &ty::ctxt<'tcx>,
|
|
amount: uint, value: &T) -> T {
|
|
debug!("shift_regions(value={}, amount={})",
|
|
value.repr(tcx), amount);
|
|
|
|
value.fold_with(&mut RegionFolder::new(tcx, |region, _current_depth| {
|
|
shift_region(region, amount)
|
|
}))
|
|
}
|
|
|