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Search directly for the largest and smallest variants instead of sorting

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This commit is contained in:
Owen Sanchez 2017-02-06 12:25:38 -07:00
parent 96ae7da9b6
commit 45a7012fd9
1 changed files with 17 additions and 12 deletions
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29
clippy_lints/src/large_enum_variant.rs
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@ -51,10 +51,10 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant {
let ty = cx.tcx.item_type(did);
let adt = ty.ty_adt_def().expect("already checked whether this is an enum");
let mut sizes = Vec::new();
let mut variants = Vec::new();
let mut smallest_variant: Option<(_, _)> = None;
let mut largest_variant: Option<(_, _)> = None;
for variant in &adt.variants {
for (i, variant) in adt.variants.iter().enumerate() {
let data_layout = TargetDataLayout::parse(cx.sess());
cx.tcx.infer_ctxt((), Reveal::All).enter(|infcx| {
let size: u64 = variant.fields
@ -72,18 +72,13 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant {
})
.sum();
sizes.push(size);
variants.push(variant);
let grouped = (size, (i, variant));
update_if(&mut smallest_variant, grouped, |a, b| b.0 <= a.0);
update_if(&mut largest_variant, grouped, |a, b| b.0 >= a.0);
});
}
let mut grouped = sizes.into_iter().zip(variants.into_iter().enumerate()).collect::<Vec<_>>();
grouped.sort_by_key(|g| g.0);
let smallest_variant = grouped.first();
let largest_variant = grouped.last();
if let (Some(smallest), Some(largest)) = (smallest_variant, largest_variant) {
let difference = largest.0 - smallest.0;
@ -118,3 +113,13 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LargeEnumVariant {
}
}
}
fn update_if<T, F>(old: &mut Option<T>, new: T, f: F) where F: Fn(&T, &T) -> bool {
if let Some(ref mut val) = *old {
if f(val, &new) {
*val = new;
}
} else {
*old = Some(new);
}
}