Merge branch 'refactor-select' of https://github.com/aravind-pg/rust into update...

[rust.git] / src / libcore / iter / mod.rs

diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index 623cad754dd7274221efea7a9a7a22c4a9b314ba..a6802d606ca8cbbc849e6c5bf468bed73763347b 100644 (file)
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -344,7 +344,7 @@
 pub use self::traits::{FromIterator, IntoIterator, DoubleEndedIterator, Extend};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::traits::{ExactSizeIterator, Sum, Product};
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 pub use self::traits::FusedIterator;
 #[unstable(feature = "trusted_len", issue = "37572")]
 pub use self::traits::TrustedLen;
@@ -506,7 +506,7 @@ fn is_empty(&self) -> bool {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> FusedIterator for Rev<I>
     where I: FusedIterator + DoubleEndedIterator {}
 
@@ -589,7 +589,7 @@ fn is_empty(&self) -> bool {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<'a, I, T: 'a> FusedIterator for Cloned<I>
     where I: FusedIterator<Item=&'a T>, T: Clone
 {}
@@ -662,7 +662,7 @@ fn size_hint(&self) -> (usize, Option<usize>) {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> FusedIterator for Cycle<I> where I: Clone + Iterator {}
 
 /// An iterator for stepping iterators by a custom amount.
@@ -1002,7 +1002,7 @@ fn rfold<Acc, F>(self, init: Acc, mut f: F) -> Acc
 }
 
 // Note: *both* must be fused to handle double-ended iterators.
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<A, B> FusedIterator for Chain<A, B>
     where A: FusedIterator,
           B: FusedIterator<Item=A::Item>,
@@ -1045,6 +1045,11 @@ fn next(&mut self) -> Option<Self::Item> {
     fn size_hint(&self) -> (usize, Option<usize>) {
         ZipImpl::size_hint(self)
     }
+
+    #[inline]
+    fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        ZipImpl::nth(self, n)
+    }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -1065,6 +1070,14 @@ trait ZipImpl<A, B> {
     fn new(a: A, b: B) -> Self;
     fn next(&mut self) -> Option<Self::Item>;
     fn size_hint(&self) -> (usize, Option<usize>);
+    fn nth(&mut self, n: usize) -> Option<Self::Item>;
+    fn super_nth(&mut self, mut n: usize) -> Option<Self::Item> {
+        while let Some(x) = self.next() {
+            if n == 0 { return Some(x) }
+            n -= 1;
+        }
+        None
+    }
     fn next_back(&mut self) -> Option<Self::Item>
         where A: DoubleEndedIterator + ExactSizeIterator,
               B: DoubleEndedIterator + ExactSizeIterator;
@@ -1094,6 +1107,11 @@ impl<A, B> ZipImpl<A, B> for Zip<A, B>
         })
     }
 
+    #[inline]
+    default fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        self.super_nth(n)
+    }
+
     #[inline]
     default fn next_back(&mut self) -> Option<(A::Item, B::Item)>
         where A: DoubleEndedIterator + ExactSizeIterator,
@@ -1174,6 +1192,24 @@ fn size_hint(&self) -> (usize, Option<usize>) {
         (len, Some(len))
     }
 
+    #[inline]
+    fn nth(&mut self, n: usize) -> Option<Self::Item> {
+        let delta = cmp::min(n, self.len - self.index);
+        let end = self.index + delta;
+        while self.index < end {
+            let i = self.index;
+            self.index += 1;
+            if A::may_have_side_effect() {
+                unsafe { self.a.get_unchecked(i); }
+            }
+            if B::may_have_side_effect() {
+                unsafe { self.b.get_unchecked(i); }
+            }
+        }
+
+        self.super_nth(n - delta)
+    }
+
     #[inline]
     fn next_back(&mut self) -> Option<(A::Item, B::Item)>
         where A: DoubleEndedIterator + ExactSizeIterator,
@@ -1226,7 +1262,7 @@ fn may_have_side_effect() -> bool {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<A, B> FusedIterator for Zip<A, B>
     where A: FusedIterator, B: FusedIterator, {}
 
@@ -1368,7 +1404,7 @@ fn is_empty(&self) -> bool {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<B, I: FusedIterator, F> FusedIterator for Map<I, F>
     where F: FnMut(I::Item) -> B {}
 
@@ -1517,7 +1553,7 @@ fn rfold<Acc, Fold>(self, init: Acc, mut fold: Fold) -> Acc
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I: FusedIterator, P> FusedIterator for Filter<I, P>
     where P: FnMut(&I::Item) -> bool {}
 
@@ -1627,7 +1663,7 @@ fn rfold<Acc, Fold>(self, init: Acc, mut fold: Fold) -> Acc
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<B, I: FusedIterator, F> FusedIterator for FilterMap<I, F>
     where F: FnMut(I::Item) -> Option<B> {}
 
@@ -1782,7 +1818,7 @@ fn may_have_side_effect() -> bool {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> FusedIterator for Enumerate<I> where I: FusedIterator {}
 
 #[unstable(feature = "trusted_len", issue = "37572")]
@@ -1902,7 +1938,7 @@ fn fold<Acc, Fold>(self, init: Acc, mut fold: Fold) -> Acc
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<I: ExactSizeIterator> ExactSizeIterator for Peekable<I> {}
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I: FusedIterator> FusedIterator for Peekable<I> {}
 
 impl<I: Iterator> Peekable<I> {
@@ -2036,7 +2072,7 @@ fn fold<Acc, Fold>(mut self, mut init: Acc, mut fold: Fold) -> Acc
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I, P> FusedIterator for SkipWhile<I, P>
     where I: FusedIterator, P: FnMut(&I::Item) -> bool {}
 
@@ -2115,7 +2151,7 @@ fn try_fold<Acc, Fold, R>(&mut self, init: Acc, mut fold: Fold) -> R where
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I, P> FusedIterator for TakeWhile<I, P>
     where I: FusedIterator, P: FnMut(&I::Item) -> bool {}
 
@@ -2254,7 +2290,7 @@ fn try_rfold<Acc, Fold, R>(&mut self, init: Acc, mut fold: Fold) -> R where
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> FusedIterator for Skip<I> where I: FusedIterator {}
 
 /// An iterator that only iterates over the first `n` iterations of `iter`.
@@ -2335,7 +2371,7 @@ fn try_fold<Acc, Fold, R>(&mut self, init: Acc, mut fold: Fold) -> R where
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<I> ExactSizeIterator for Take<I> where I: ExactSizeIterator {}
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> FusedIterator for Take<I> where I: FusedIterator {}
 
 #[unstable(feature = "trusted_len", issue = "37572")]
@@ -2481,7 +2517,7 @@ fn rfold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I, U, F> FusedIterator for FlatMap<I, U, F>
     where I: FusedIterator, U: IntoIterator, F: FnMut(I::Item) -> U {}
 
@@ -2569,7 +2605,7 @@ fn rfold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I, U> FusedIterator for Flatten<I>
     where I: FusedIterator, U: Iterator,
           I::Item: IntoIterator<IntoIter = U, Item = U::Item> {}
@@ -2729,7 +2765,7 @@ pub struct Fuse<I> {
     done: bool
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> FusedIterator for Fuse<I> where I: Iterator {}
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -2860,7 +2896,7 @@ fn may_have_side_effect() -> bool {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> Iterator for Fuse<I> where I: FusedIterator {
     #[inline]
     fn next(&mut self) -> Option<<I as Iterator>::Item> {
@@ -2902,7 +2938,7 @@ fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
     }
 }
 
-#[unstable(feature = "fused", reason = "recently added", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I> DoubleEndedIterator for Fuse<I>
     where I: DoubleEndedIterator + FusedIterator
 {
@@ -3046,6 +3082,6 @@ fn is_empty(&self) -> bool {
     }
 }
 
-#[unstable(feature = "fused", issue = "35602")]
+#[stable(feature = "fused", since = "1.26.0")]
 impl<I: FusedIterator, F> FusedIterator for Inspect<I, F>
     where F: FnMut(&I::Item) {}