| // Copyright 2012-2014 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. |
| |
| //! An iterator over the type substructure. |
| //! WARNING: this does not keep track of the region depth. |
| |
| use ty::{self, Ty}; |
| use std::iter::Iterator; |
| use std::vec::IntoIter; |
| |
| pub struct TypeWalker<'tcx> { |
| stack: Vec<Ty<'tcx>>, |
| last_subtree: usize, |
| } |
| |
| impl<'tcx> TypeWalker<'tcx> { |
| pub fn new(ty: Ty<'tcx>) -> TypeWalker<'tcx> { |
| TypeWalker { stack: vec!(ty), last_subtree: 1, } |
| } |
| |
| /// Skips the subtree of types corresponding to the last type |
| /// returned by `next()`. |
| /// |
| /// Example: Imagine you are walking `Foo<Bar<int>, usize>`. |
| /// |
| /// ``` |
| /// let mut iter: TypeWalker = ...; |
| /// iter.next(); // yields Foo |
| /// iter.next(); // yields Bar<int> |
| /// iter.skip_current_subtree(); // skips int |
| /// iter.next(); // yields usize |
| /// ``` |
| 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>) -> IntoIter<Ty<'tcx>> { |
| let mut stack = vec![]; |
| push_subtypes(&mut stack, ty); |
| stack.into_iter() |
| } |
| |
| fn push_subtypes<'tcx>(stack: &mut Vec<Ty<'tcx>>, parent_ty: Ty<'tcx>) { |
| match parent_ty.sty { |
| ty::TyBool | ty::TyChar | ty::TyInt(_) | ty::TyUint(_) | ty::TyFloat(_) | |
| ty::TyStr | ty::TyInfer(_) | ty::TyParam(_) | ty::TyError => { |
| } |
| ty::TyBox(ty) | ty::TyArray(ty, _) | ty::TySlice(ty) => { |
| stack.push(ty); |
| } |
| ty::TyRawPtr(ref mt) | ty::TyRef(_, ref mt) => { |
| stack.push(mt.ty); |
| } |
| ty::TyProjection(ref data) => { |
| push_reversed(stack, data.trait_ref.substs.types.as_slice()); |
| } |
| ty::TyTrait(box ty::TraitTy { ref principal, ref bounds }) => { |
| push_reversed(stack, principal.substs().types.as_slice()); |
| push_reversed(stack, &bounds.projection_bounds.iter().map(|pred| { |
| pred.0.ty |
| }).collect::<Vec<_>>()); |
| } |
| ty::TyEnum(_, ref substs) | |
| ty::TyStruct(_, ref substs) => { |
| push_reversed(stack, substs.types.as_slice()); |
| } |
| ty::TyClosure(_, ref substs) => { |
| push_reversed(stack, substs.func_substs.types.as_slice()); |
| push_reversed(stack, &substs.upvar_tys); |
| } |
| ty::TyTuple(ref ts) => { |
| push_reversed(stack, ts); |
| } |
| ty::TyFnDef(_, substs, ref ft) => { |
| push_reversed(stack, substs.types.as_slice()); |
| push_sig_subtypes(stack, &ft.sig); |
| } |
| ty::TyFnPtr(ref ft) => { |
| push_sig_subtypes(stack, &ft.sig); |
| } |
| } |
| } |
| |
| fn push_sig_subtypes<'tcx>(stack: &mut Vec<Ty<'tcx>>, sig: &ty::PolyFnSig<'tcx>) { |
| match sig.0.output { |
| ty::FnConverging(output) => { stack.push(output); } |
| ty::FnDiverging => { } |
| } |
| push_reversed(stack, &sig.0.inputs); |
| } |
| |
| fn push_reversed<'tcx>(stack: &mut Vec<Ty<'tcx>>, tys: &[Ty<'tcx>]) { |
| // We push slices on the stack in reverse order so as to |
| // maintain a pre-order traversal. As of the time of this |
| // writing, the fact that the traversal is pre-order is not |
| // known to be significant to any code, but it seems like the |
| // natural order one would expect (basically, the order of the |
| // types as they are written). |
| for &ty in tys.iter().rev() { |
| stack.push(ty); |
| } |
| } |