1 // Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! The move-analysis portion of borrowck needs to work in an abstract
12 //! domain of lifted Lvalues. Most of the Lvalue variants fall into a
13 //! one-to-one mapping between the concrete and abstract (e.g. a
14 //! field-deref on a local-variable, `x.field`, has the same meaning
15 //! in both domains). Indexed-Projections are the exception: `a[x]`
16 //! needs to be treated as mapping to the same move path as `a[y]` as
17 //! well as `a[13]`, et cetera.
19 //! (In theory the analysis could be extended to work with sets of
20 //! paths, so that `a[0]` and `a[13]` could be kept distinct, while
21 //! `a[x]` would still overlap them both. But that is not this
22 //! representation does today.)
24 use rustc
::mir
::repr
::{Lvalue, LvalueElem}
;
25 use rustc
::mir
::repr
::{Operand, Projection, ProjectionElem}
;
27 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
28 pub struct AbstractOperand
;
29 pub type AbstractProjection
<'tcx
> =
30 Projection
<'tcx
, Lvalue
<'tcx
>, AbstractOperand
>;
31 pub type AbstractElem
<'tcx
> =
32 ProjectionElem
<'tcx
, AbstractOperand
>;
36 fn lift(&self) -> Self::Abstract
;
38 impl<'tcx
> Lift
for Operand
<'tcx
> {
39 type Abstract
= AbstractOperand
;
40 fn lift(&self) -> Self::Abstract { AbstractOperand }
42 impl<'tcx
> Lift
for LvalueElem
<'tcx
> {
43 type Abstract
= AbstractElem
<'tcx
>;
44 fn lift(&self) -> Self::Abstract
{
46 ProjectionElem
::Deref
=>
47 ProjectionElem
::Deref
,
48 ProjectionElem
::Field(ref f
, ty
) =>
49 ProjectionElem
::Field(f
.clone(), ty
.clone()),
50 ProjectionElem
::Index(ref i
) =>
51 ProjectionElem
::Index(i
.lift()),
52 ProjectionElem
::ConstantIndex {offset,min_length,from_end}
=>
53 ProjectionElem
::ConstantIndex
{
55 min_length
: min_length
,
58 ProjectionElem
::Downcast(a
, u
) =>
59 ProjectionElem
::Downcast(a
.clone(), u
.clone()),