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iterator: add a size_hint default method

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also adds an implementation for the vector iterators
This commit is contained in:
Daniel Micay 2013-06-21 06:12:01 -04:00
parent df166bae1f
commit 468cbd9d01
2 changed files with 70 additions and 6 deletions
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27
src/libstd/vec.rs
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@ -29,6 +29,7 @@ use ptr::to_unsafe_ptr;
use ptr;
use ptr::RawPtr;
use sys;
use sys::size_of;
use uint;
use unstable::intrinsics;
use vec;
@ -2454,6 +2455,13 @@ macro_rules! iterator {
}
}
}
#[inline]
#[cfg(not(stage0))]
fn size_hint(&self) -> (Option<uint>, Option<uint>) {
let exact = Some(((self.end as uint) - (self.ptr as uint)) / size_of::<$elem>());
(exact, exact)
}
}
}
}
@ -3909,16 +3917,23 @@ mod tests {
}
#[test]
#[cfg(not(stage0))]
fn test_iterator() {
use iterator::*;
let xs = [1, 2, 5, 10, 11];
let ys = [1, 2, 5, 10, 11, 19];
let mut it = xs.iter();
let mut i = 0;
for it.advance |&x| {
assert_eq!(x, ys[i]);
i += 1;
}
assert_eq!(it.size_hint(), (Some(5), Some(5)));
assert_eq!(it.next().unwrap(), &1);
assert_eq!(it.size_hint(), (Some(4), Some(4)));
assert_eq!(it.next().unwrap(), &2);
assert_eq!(it.size_hint(), (Some(3), Some(3)));
assert_eq!(it.next().unwrap(), &5);
assert_eq!(it.size_hint(), (Some(2), Some(2)));
assert_eq!(it.next().unwrap(), &10);
assert_eq!(it.size_hint(), (Some(1), Some(1)));
assert_eq!(it.next().unwrap(), &11);
assert_eq!(it.size_hint(), (Some(0), Some(0)));
assert!(it.next().is_none());
}
#[test]