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use mir::interpret::ConstValue;
use ty::{self, Ty};
use smallvec::{self, SmallVec};
pub type TypeWalkerArray<'tcx> = [Ty<'tcx>; 8];
pub type TypeWalkerStack<'tcx> = SmallVec<TypeWalkerArray<'tcx>>;
pub struct TypeWalker<'tcx> {
stack: TypeWalkerStack<'tcx>,
last_subtree: usize,
}
impl<'tcx> TypeWalker<'tcx> {
pub fn new(ty: Ty<'tcx>) -> TypeWalker<'tcx> {
TypeWalker { stack: smallvec![ty], last_subtree: 1, }
}
pub fn skip_current_subtree(&mut self) {
self.stack.truncate(self.last_subtree);
}
}
impl<'tcx> Iterator for TypeWalker<'tcx> {
type Item = Ty<'tcx>;
fn next(&mut self) -> Option<Ty<'tcx>> {
debug!("next(): stack={:?}", self.stack);
match self.stack.pop() {
None => {
return None;
}
Some(ty) => {
self.last_subtree = self.stack.len();
push_subtypes(&mut self.stack, ty);
debug!("next: stack={:?}", self.stack);
Some(ty)
}
}
}
}
pub fn walk_shallow<'tcx>(ty: Ty<'tcx>) -> smallvec::IntoIter<TypeWalkerArray<'tcx>> {
let mut stack = SmallVec::new();
push_subtypes(&mut stack, ty);
stack.into_iter()
}
fn push_subtypes<'tcx>(stack: &mut TypeWalkerStack<'tcx>, parent_ty: Ty<'tcx>) {
match parent_ty.sty {
ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) |
ty::Str | ty::Infer(_) | ty::Param(_) | ty::Never | ty::Error |
ty::Foreign(..) => {
}
ty::Array(ty, len) => {
push_const(stack, len);
stack.push(ty);
}
ty::Slice(ty) => {
stack.push(ty);
}
ty::RawPtr(ref mt) => {
stack.push(mt.ty);
}
ty::Ref(_, ty, _) => {
stack.push(ty);
}
ty::Projection(ref data) => {
stack.extend(data.substs.types().rev());
}
ty::Dynamic(ref obj, ..) => {
stack.extend(obj.iter().rev().flat_map(|predicate| {
let (substs, opt_ty) = match *predicate.skip_binder() {
ty::ExistentialPredicate::Trait(tr) => (tr.substs, None),
ty::ExistentialPredicate::Projection(p) =>
(p.substs, Some(p.ty)),
ty::ExistentialPredicate::AutoTrait(_) =>
(ty::Substs::empty(), None),
};
substs.types().rev().chain(opt_ty)
}));
}
ty::Adt(_, substs) | ty::Opaque(_, substs) => {
stack.extend(substs.types().rev());
}
ty::Closure(_, ref substs) => {
stack.extend(substs.substs.types().rev());
}
ty::Generator(_, ref substs, _) => {
stack.extend(substs.substs.types().rev());
}
ty::GeneratorWitness(ts) => {
stack.extend(ts.skip_binder().iter().cloned().rev());
}
ty::Tuple(ts) => {
stack.extend(ts.iter().cloned().rev());
}
ty::FnDef(_, substs) => {
stack.extend(substs.types().rev());
}
ty::FnPtr(sig) => {
stack.push(sig.skip_binder().output());
stack.extend(sig.skip_binder().inputs().iter().cloned().rev());
}
}
}
fn push_const<'tcx>(stack: &mut TypeWalkerStack<'tcx>, constant: &'tcx ty::Const<'tcx>) {
if let ConstValue::Unevaluated(_, substs) = constant.val {
stack.extend(substs.types().rev());
}
stack.push(constant.ty);
}