bjoernager/rust
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change to 0-based indices

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Co-authored-by: csmoe <35686186+csmoe@users.noreply.github.com>
This commit is contained in:
Niko Matsakis 2018-05-28 13:19:04 -04:00
parent 22a25d9b49
commit 783fe4f880
14 changed files with 27 additions and 27 deletions
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24
src/librustc/ty/sty.rs
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@ -989,11 +989,11 @@ impl<'a, 'gcx, 'tcx> ParamTy {
/// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
/// ^ ^ | | |
/// | | | | |
/// | +------------+ 1 | |
/// | +------------+ 0 | |
/// | | |
/// +--------------------------------+ 2 |
/// +--------------------------------+ 1 |
/// | |
/// +------------------------------------------+ 1
/// +------------------------------------------+ 0
///
/// In this type, there are two binders (the outer fn and the inner
/// fn). We need to be able to determine, for any given region, which
@ -1005,9 +1005,9 @@ impl<'a, 'gcx, 'tcx> ParamTy {
///
/// Let's start with the reference type `&'b isize` that is the first
/// argument to the inner function. This region `'b` is assigned a De
/// Bruijn index of 1, meaning "the innermost binder" (in this case, a
/// Bruijn index of 0, meaning "the innermost binder" (in this case, a
/// fn). The region `'a` that appears in the second argument type (`&'a
/// isize`) would then be assigned a De Bruijn index of 2, meaning "the
/// isize`) would then be assigned a De Bruijn index of 1, meaning "the
/// second-innermost binder". (These indices are written on the arrays
/// in the diagram).
///
@ -1017,7 +1017,7 @@ impl<'a, 'gcx, 'tcx> ParamTy {
/// the outermost fn. But this time, this reference is not nested within
/// any other binders (i.e., it is not an argument to the inner fn, but
/// rather the outer one). Therefore, in this case, it is assigned a
/// De Bruijn index of 1, because the innermost binder in that location
/// De Bruijn index of 0, because the innermost binder in that location
/// is the outer fn.
///
/// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
@ -1025,7 +1025,7 @@ impl<'a, 'gcx, 'tcx> ParamTy {
pub struct DebruijnIndex {
/// We maintain the invariant that this is never 0. So 1 indicates
/// the innermost binder.
depth: u32,
index: u32,
}
pub type Region<'tcx> = &'tcx RegionKind;
@ -1259,7 +1259,7 @@ impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
}
impl DebruijnIndex {
pub const INNERMOST: DebruijnIndex = DebruijnIndex { depth: 1 };
pub const INNERMOST: DebruijnIndex = DebruijnIndex { index: 0 };
/// Returns the resulting index when this value is moved into
/// `amount` number of new binders. So e.g. if you had
@ -1273,7 +1273,7 @@ impl DebruijnIndex {
/// you would need to shift the index for `'a` into 1 new binder.
#[must_use]
pub const fn shifted_in(self, amount: u32) -> DebruijnIndex {
DebruijnIndex { depth: self.depth + amount }
DebruijnIndex { index: self.index + amount }
}
/// Update this index in place by shifting it "in" through
@ -1286,7 +1286,7 @@ impl DebruijnIndex {
/// `amount` number of new binders.
#[must_use]
pub const fn shifted_out(self, amount: u32) -> DebruijnIndex {
DebruijnIndex { depth: self.depth - amount }
DebruijnIndex { index: self.index - amount }
}
/// Update in place by shifting out from `amount` binders.
@ -1315,12 +1315,12 @@ impl DebruijnIndex {
/// bound by one of the binders we are shifting out of, that is an
/// error (and should fail an assertion failure).
pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
self.shifted_out(to_binder.depth - Self::INNERMOST.depth)
self.shifted_out(to_binder.index - Self::INNERMOST.index)
}
}
impl_stable_hash_for!(struct DebruijnIndex {
depth
index
});
/// Region utilities