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Add checks to guard against overflow in iterator methods. #76

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merged 1 commit into from Nov 17, 2019
Merged

Add checks to guard against overflow in iterator methods. #76

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6 changes: 4 additions & 2 deletions strum_macros/src/macros/enum_iter.rs
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Expand Up @@ -83,12 +83,14 @@ pub fn enum_iter_inner(ast: &syn::DeriveInput) -> TokenStream {
#(#arms),*
};

self.idx += 1;
if self.idx < #variant_count {
self.idx += 1;
}
output
}

fn size_hint(&self) -> (usize, Option<usize>) {
let t = #variant_count - self.idx;
let t = if self.idx >= #variant_count { 0 } else { #variant_count - self.idx };
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Looks like this is unnecessary given that the above guarantees this will never underflow.

Additionally, this property is FusedIterator (which is not a requirement for Iterator, and it's the responsibility of the caller to stop calling it). If we choose to have it, then we should also signify that we have it by implementing FusedIterator.

(t, Some(t))
}
}
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3 changes: 3 additions & 0 deletions strum_tests/tests/enum_iter.rs
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Expand Up @@ -63,6 +63,9 @@ fn len_test() {
i.next();

assert_eq!(0, i.len());
i.next();

assert_eq!(0, i.size_hint().1.unwrap());
}

#[test]
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