| //! The move-analysis portion of borrowck needs to work in an abstract |
| //! domain of lifted `Place`s. Most of the `Place` variants fall into a |
| //! one-to-one mapping between the concrete and abstract (e.g., a |
| //! field-deref on a local variable, `x.field`, has the same meaning |
| //! in both domains). Indexed projections are the exception: `a[x]` |
| //! needs to be treated as mapping to the same move path as `a[y]` as |
| //! well as `a[13]`, etc. |
| //! |
| //! (In theory, the analysis could be extended to work with sets of |
| //! paths, so that `a[0]` and `a[13]` could be kept distinct, while |
| //! `a[x]` would still overlap them both. But that is not this |
| //! representation does today.) |
| |
| use rustc::mir::{Local, Operand, PlaceElem, ProjectionElem}; |
| use rustc::ty::Ty; |
| |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
| pub struct AbstractOperand; |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
| pub struct AbstractType; |
| pub type AbstractElem = ProjectionElem<AbstractOperand, AbstractType>; |
| |
| pub trait Lift { |
| type Abstract; |
| fn lift(&self) -> Self::Abstract; |
| } |
| impl<'tcx> Lift for Operand<'tcx> { |
| type Abstract = AbstractOperand; |
| fn lift(&self) -> Self::Abstract { |
| AbstractOperand |
| } |
| } |
| impl Lift for Local { |
| type Abstract = AbstractOperand; |
| fn lift(&self) -> Self::Abstract { |
| AbstractOperand |
| } |
| } |
| impl<'tcx> Lift for Ty<'tcx> { |
| type Abstract = AbstractType; |
| fn lift(&self) -> Self::Abstract { |
| AbstractType |
| } |
| } |
| impl<'tcx> Lift for PlaceElem<'tcx> { |
| type Abstract = AbstractElem; |
| fn lift(&self) -> Self::Abstract { |
| match *self { |
| ProjectionElem::Deref => ProjectionElem::Deref, |
| ProjectionElem::Field(ref f, ty) => ProjectionElem::Field(f.clone(), ty.lift()), |
| ProjectionElem::Index(ref i) => ProjectionElem::Index(i.lift()), |
| ProjectionElem::Subslice { from, to } => { |
| ProjectionElem::Subslice { from: from, to: to } |
| } |
| ProjectionElem::ConstantIndex { offset, min_length, from_end } => { |
| ProjectionElem::ConstantIndex { offset, min_length, from_end } |
| } |
| ProjectionElem::Downcast(a, u) => ProjectionElem::Downcast(a, u.clone()), |
| } |
| } |
| } |