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Implement len() for EnumSet. #18740

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Implement len() for EnumSet. #18740

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21 changes: 20 additions & 1 deletion src/libcollections/enum_set.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@ use core::fmt;

// FIXME(conventions): implement BitXor
// FIXME(contentions): implement union family of methods? (general design may be wrong here)
// FIXME(conventions): implement len

#[deriving(Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
/// A specialized `Set` implementation to use enum types.
Expand Down Expand Up @@ -92,6 +91,12 @@ impl<E:CLike> EnumSet<E> {
EnumSet {bits: 0}
}

/// Returns the number of elements in the given `EnumSet`.
#[unstable = "matches collection reform specification, waiting for dust to settle"]
pub fn len(&self) -> uint {
self.bits.count_ones()
}

/// Returns true if the `EnumSet` is empty.
#[unstable = "matches collection reform specification, waiting for dust to settle"]
pub fn is_empty(&self) -> bool {
Expand Down Expand Up @@ -269,6 +274,20 @@ mod test {
assert_eq!("{A, C}", e.to_string().as_slice());
}

#[test]
fn test_len() {
let mut e = EnumSet::new();
assert_eq!(e.len(), 0);
e.insert(A);
e.insert(B);
e.insert(C);
assert_eq!(e.len(), 3);
e.remove(&A);
assert_eq!(e.len(), 2);
e.clear();
assert_eq!(e.len(), 0);
}

///////////////////////////////////////////////////////////////////////////
// intersect

Expand Down