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@ -319,10 +319,9 @@
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use cmp;
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use fmt;
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use iter_private::TrustedRandomAccess;
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use ops::{self, Try};
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use ops::Try;
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use usize;
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use intrinsics;
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use mem;
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use self::iterator::Iterator;
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@ -673,7 +672,12 @@ impl<I> Iterator for StepBy<I> where I: Iterator {
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#[inline]
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fn next(&mut self) -> Option<Self::Item> {
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<Self as StepBySpecIterator>::spec_next(self)
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if self.first_take {
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self.first_take = false;
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self.iter.next()
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} else {
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self.iter.nth(self.step)
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}
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}
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#[inline]
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@ -733,78 +737,6 @@ impl<I> Iterator for StepBy<I> where I: Iterator {
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}
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}
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// hidden trait for specializing iterator methods
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// could be generalized but is currently only used for StepBy
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trait StepBySpecIterator {
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type Item;
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fn spec_next(&mut self) -> Option<Self::Item>;
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}
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impl<I> StepBySpecIterator for StepBy<I>
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where
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I: Iterator,
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{
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type Item = I::Item;
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#[inline]
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default fn spec_next(&mut self) -> Option<I::Item> {
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if self.first_take {
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self.first_take = false;
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self.iter.next()
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} else {
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self.iter.nth(self.step)
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}
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}
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}
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impl<T> StepBySpecIterator for StepBy<ops::Range<T>>
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where
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T: Step,
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{
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#[inline]
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fn spec_next(&mut self) -> Option<Self::Item> {
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self.first_take = false;
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if !(self.iter.start < self.iter.end) {
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return None;
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}
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// add 1 to self.step to get original step size back
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// it was decremented for the general case on construction
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if let Some(n) = self.iter.start.add_usize(self.step+1) {
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let next = mem::replace(&mut self.iter.start, n);
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Some(next)
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} else {
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let last = self.iter.start.clone();
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self.iter.start = self.iter.end.clone();
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Some(last)
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}
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}
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}
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impl<T> StepBySpecIterator for StepBy<ops::RangeInclusive<T>>
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where
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T: Step,
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{
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#[inline]
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fn spec_next(&mut self) -> Option<Self::Item> {
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self.first_take = false;
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self.iter.compute_is_empty();
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if self.iter.is_empty.unwrap_or_default() {
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return None;
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}
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// add 1 to self.step to get original step size back
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// it was decremented for the general case on construction
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if let Some(n) = self.iter.start.add_usize(self.step+1) {
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self.iter.is_empty = Some(!(n <= self.iter.end));
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let next = mem::replace(&mut self.iter.start, n);
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Some(next)
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} else {
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let last = self.iter.start.clone();
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self.iter.is_empty = Some(true);
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Some(last)
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}
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}
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}
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// StepBy can only make the iterator shorter, so the len will still fit.
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#[stable(feature = "iterator_step_by", since = "1.28.0")]
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impl<I> ExactSizeIterator for StepBy<I> where I: ExactSizeIterator {}
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@ -1619,11 +1619,8 @@ fn test_range_step() {
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}
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#[test]
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fn test_range_inclusive_step() {
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assert_eq!((0..=50).step_by(10).collect::<Vec<_>>(), [0, 10, 20, 30, 40, 50]);
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assert_eq!((0..=5).step_by(1).collect::<Vec<_>>(), [0, 1, 2, 3, 4, 5]);
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assert_eq!((200..=255u8).step_by(10).collect::<Vec<_>>(), [200, 210, 220, 230, 240, 250]);
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assert_eq!((250..=255u8).step_by(1).collect::<Vec<_>>(), [250, 251, 252, 253, 254, 255]);
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fn test_step_by_skip() {
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assert_eq!((0..640).step_by(128).skip(1).collect::<Vec<_>>(), [128, 256, 384, 512]);
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}
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#[test]
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