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Extract constructor application as a Constructor method

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Nadrieril 2019-09-23 17:36:42 +02:00 • committed by Nadrieril
parent 0c02c19ac8
commit b45458124e
1 changed files with 64 additions and 42 deletions
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106
src/librustc_mir/hair/pattern/_match.rs
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@ -674,6 +674,67 @@ impl<'tcx> Constructor<'tcx> {
_ => 0,
}
}
/// Apply a constructor to a list of patterns, yielding a new pattern. `pats`
/// must have as many elements as this constructor's arity.
///
/// Examples:
/// self: Single
/// ty: tuple of 3 elements
/// pats: [10, 20, _] => (10, 20, _)
///
/// self: Option::Some
/// ty: Option<bool>
/// pats: [false] => Some(false)
fn apply<'a>(
&self,
cx: &MatchCheckCtxt<'a, 'tcx>,
ty: Ty<'tcx>,
pats: impl IntoIterator<Item = Pat<'tcx>>,
) -> Pat<'tcx> {
let mut pats = pats.into_iter();
let pat = match ty.kind {
ty::Adt(..) | ty::Tuple(..) => {
let pats = pats
.enumerate()
.map(|(i, p)| FieldPat { field: Field::new(i), pattern: p })
.collect();
if let ty::Adt(adt, substs) = ty.kind {
if adt.is_enum() {
PatKind::Variant {
adt_def: adt,
substs,
variant_index: self.variant_index_for_adt(cx, adt),
subpatterns: pats,
}
} else {
PatKind::Leaf { subpatterns: pats }
}
} else {
PatKind::Leaf { subpatterns: pats }
}
}
ty::Ref(..) => PatKind::Deref { subpattern: pats.nth(0).unwrap() },
ty::Slice(_) | ty::Array(..) => {
PatKind::Slice { prefix: pats.collect(), slice: None, suffix: vec![] }
}
_ => match *self {
ConstantValue(value, _) => PatKind::Constant { value },
ConstantRange(lo, hi, ty, end, _) => PatKind::Range(PatRange {
lo: ty::Const::from_bits(cx.tcx, lo, ty::ParamEnv::empty().and(ty)),
hi: ty::Const::from_bits(cx.tcx, hi, ty::ParamEnv::empty().and(ty)),
end,
}),
_ => PatKind::Wild,
},
};
Pat { ty, span: DUMMY_SP, kind: Box::new(pat) }
}
}
#[derive(Clone, Debug)]
@ -778,50 +839,11 @@ impl<'tcx> Witness<'tcx> {
let arity = ctor.arity(cx, ty);
let pat = {
let len = self.0.len() as u64;
let mut pats = self.0.drain((len - arity) as usize..).rev();
match ty.kind {
ty::Adt(..) | ty::Tuple(..) => {
let pats = pats
.enumerate()
.map(|(i, p)| FieldPat { field: Field::new(i), pattern: p })
.collect();
if let ty::Adt(adt, substs) = ty.kind {
if adt.is_enum() {
PatKind::Variant {
adt_def: adt,
substs,
variant_index: ctor.variant_index_for_adt(cx, adt),
subpatterns: pats,
}
} else {
PatKind::Leaf { subpatterns: pats }
}
} else {
PatKind::Leaf { subpatterns: pats }
}
}
ty::Ref(..) => PatKind::Deref { subpattern: pats.nth(0).unwrap() },
ty::Slice(_) | ty::Array(..) => {
PatKind::Slice { prefix: pats.collect(), slice: None, suffix: vec![] }
}
_ => match *ctor {
ConstantValue(value, _) => PatKind::Constant { value },
ConstantRange(lo, hi, ty, end, _) => PatKind::Range(PatRange {
lo: ty::Const::from_bits(cx.tcx, lo, ty::ParamEnv::empty().and(ty)),
hi: ty::Const::from_bits(cx.tcx, hi, ty::ParamEnv::empty().and(ty)),
end,
}),
_ => PatKind::Wild,
},
}
let pats = self.0.drain((len - arity) as usize..).rev();
ctor.apply(cx, ty, pats)
};
self.0.push(Pat { ty, span: DUMMY_SP, kind: Box::new(pat) });
self.0.push(pat);
self
}