Override size_hint and implement ExactSizeIterator

Author: sfackler

src/array.rs

@@ -273,6 +273,10 @@ impl<'a, T: 'a> Iterator for Iter<'a, T> {
     fn next(&mut self) -> Option<&'a T> {
         self.inner.next()
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
 }
 
 impl<'a, T: 'a> DoubleEndedIterator for Iter<'a, T> {
@@ -281,6 +285,12 @@ impl<'a, T: 'a> DoubleEndedIterator for Iter<'a, T> {
     }
 }
 
+impl<'a, T: 'a> ExactSizeIterator for Iter<'a, T> {
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
 /// An iterator over mutable references to values of an `Array` in the
 /// higher-dimensional equivalent of row-major order.
 pub struct IterMut<'a, T: 'a> {
@@ -293,6 +303,10 @@ impl<'a, T: 'a> Iterator for IterMut<'a, T> {
     fn next(&mut self) -> Option<&'a mut T> {
         self.inner.next()
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
 }
 
 impl<'a, T: 'a> DoubleEndedIterator for IterMut<'a, T> {
@@ -301,6 +315,12 @@ impl<'a, T: 'a> DoubleEndedIterator for IterMut<'a, T> {
     }
 }
 
+impl<'a, T: 'a> ExactSizeIterator for IterMut<'a, T> {
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
 /// An iterator over values of an `Array` in the higher-dimensional
 /// equivalent of row-major order.
 pub struct IntoIter<T> {
@@ -313,10 +333,20 @@ impl<T> Iterator for IntoIter<T> {
     fn next(&mut self) -> Option<T> {
         self.inner.next()
     }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
 }
 
 impl<T> DoubleEndedIterator for IntoIter<T> {
     fn next_back(&mut self) -> Option<T> {
         self.inner.next_back()
     }
 }
+
+impl<T> ExactSizeIterator for IntoIter<T> {
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}