squash commit for nth_back on chunks exact
wip nth_back for chunks_exact working nth_back for chunks exact Signed-off-by: wizAmit <amitforfriends_dns@yahoo.com>
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@ -4453,6 +4453,21 @@ impl<'a, T> DoubleEndedIterator for ChunksExact<'a, T> {
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Some(snd)
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Some(snd)
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}
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}
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}
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}
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#[inline]
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fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
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let len = self.len();
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if n >= len {
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self.v = &[];
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None
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} else {
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let start = (len - 1 - n) * self.chunk_size;
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let end = start + self.chunk_size;
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let nth_back = &self.v[start..end];
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self.v = &self.v[..start];
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Some(nth_back)
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}
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}
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}
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}
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#[stable(feature = "chunks_exact", since = "1.31.0")]
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#[stable(feature = "chunks_exact", since = "1.31.0")]
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@ -275,6 +275,25 @@ fn test_chunks_exact_nth() {
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assert_eq!(c2.next(), None);
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assert_eq!(c2.next(), None);
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}
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}
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#[test]
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fn test_chunks_exact_nth_back() {
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let v: &[i32] = &[0, 1, 2, 3, 4, 5];
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let mut c = v.chunks_exact(2);
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assert_eq!(c.nth_back(1).unwrap(), &[2, 3]);
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assert_eq!(c.next().unwrap(), &[0, 1]);
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assert_eq!(c.next(), None);
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let v2: &[i32] = &[0, 1, 2, 3, 4];
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let mut c2 = v2.chunks_exact(3);
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assert_eq!(c2.nth_back(0).unwrap(), &[0, 1, 2]);
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assert_eq!(c2.next(), None);
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assert_eq!(c2.next_back(), None);
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let v3: &[i32] = &[0, 1, 2, 3, 4];
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let mut c3 = v3.chunks_exact(10);
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assert_eq!(c3.nth_back(0), None);
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}
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#[test]
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#[test]
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fn test_chunks_exact_last() {
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fn test_chunks_exact_last() {
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let v: &[i32] = &[0, 1, 2, 3, 4, 5];
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let v: &[i32] = &[0, 1, 2, 3, 4, 5];
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