Implement TrustedLen for more iterators

Author: bluss

src/libcore/iter/range.rs

@@ -480,6 +480,22 @@ macro_rules! range_incl_exact_iter_impl {
     )*)
 }
 
+macro_rules! range_trusted_len_impl {
+    ($($t:ty)*) => ($(
+        #[unstable(feature = "trusted_len", issue = "0")]
+        unsafe impl TrustedLen for ops::Range<$t> { }
+    )*)
+}
+
+macro_rules! range_incl_trusted_len_impl {
+    ($($t:ty)*) => ($(
+        #[unstable(feature = "inclusive_range",
+                   reason = "recently added, follows RFC",
+                   issue = "28237")]
+        unsafe impl TrustedLen for ops::RangeInclusive<$t> { }
+    )*)
+}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A: Step> Iterator for ops::Range<A> where
     for<'a> &'a A: Add<&'a A, Output = A>
@@ -513,6 +529,13 @@ impl<A: Step> Iterator for ops::Range<A> where
 range_exact_iter_impl!(usize u8 u16 u32 isize i8 i16 i32);
 range_incl_exact_iter_impl!(u8 u16 i8 i16);
 
+// These macros generate `TrustedLen` impls.
+//
+// They need to guarantee that .size_hint() is either exact, or that
+// the upper bound is None when it does not fit the type limits.
+range_trusted_len_impl!(usize isize u8 i8 u16 i16 u32 i32 i64 u64);
+range_incl_trusted_len_impl!(usize isize u8 i8 u16 i16 u32 i32 i64 u64);
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A: Step + Clone> DoubleEndedIterator for ops::Range<A> where
     for<'a> &'a A: Add<&'a A, Output = A>,
@@ -533,9 +556,6 @@ impl<A: Step + Clone> DoubleEndedIterator for ops::Range<A> where
 impl<A> FusedIterator for ops::Range<A>
     where A: Step, for<'a> &'a A: Add<&'a A, Output = A> {}
 
-#[unstable(feature = "trusted_len", issue = "0")]
-unsafe impl TrustedLen for ops::Range<usize> { }
-
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A: Step> Iterator for ops::RangeFrom<A> where
     for<'a> &'a A: Add<&'a A, Output = A>

src/libcore/option.rs

@@ -145,7 +145,7 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-use iter::{FromIterator, FusedIterator};
+use iter::{FromIterator, FusedIterator, TrustedLen};
 use mem;
 
 // Note that this is not a lang item per se, but it has a hidden dependency on
@@ -803,6 +803,7 @@ impl<A> DoubleEndedIterator for Item<A> {
 
 impl<A> ExactSizeIterator for Item<A> {}
 impl<A> FusedIterator for Item<A> {}
+unsafe impl<A> TrustedLen for Item<A> {}
 
 /// An iterator over a reference of the contained item in an [`Option`].
 ///
@@ -833,6 +834,9 @@ impl<'a, A> ExactSizeIterator for Iter<'a, A> {}
 #[unstable(feature = "fused", issue = "35602")]
 impl<'a, A> FusedIterator for Iter<'a, A> {}
 
+#[unstable(feature = "trusted_len", issue = "0")]
+unsafe impl<'a, A> TrustedLen for Iter<'a, A> {}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, A> Clone for Iter<'a, A> {
     fn clone(&self) -> Iter<'a, A> {
@@ -868,6 +872,8 @@ impl<'a, A> ExactSizeIterator for IterMut<'a, A> {}
 
 #[unstable(feature = "fused", issue = "35602")]
 impl<'a, A> FusedIterator for IterMut<'a, A> {}
+#[unstable(feature = "trusted_len", issue = "0")]
+unsafe impl<'a, A> TrustedLen for IterMut<'a, A> {}
 
 /// An iterator over the item contained inside an [`Option`].
 ///
@@ -898,6 +904,9 @@ impl<A> ExactSizeIterator for IntoIter<A> {}
 #[unstable(feature = "fused", issue = "35602")]
 impl<A> FusedIterator for IntoIter<A> {}
 
+#[unstable(feature = "trusted_len", issue = "0")]
+unsafe impl<A> TrustedLen for IntoIter<A> {}
+
 /////////////////////////////////////////////////////////////////////////////
 // FromIterator
 /////////////////////////////////////////////////////////////////////////////

src/libcore/result.rs

@@ -249,7 +249,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use fmt;
-use iter::{FromIterator, FusedIterator};
+use iter::{FromIterator, FusedIterator, TrustedLen};
 
 /// `Result` is a type that represents either success (`Ok`) or failure (`Err`).
 ///
@@ -886,6 +886,9 @@ impl<'a, T> ExactSizeIterator for Iter<'a, T> {}
 #[unstable(feature = "fused", issue = "35602")]
 impl<'a, T> FusedIterator for Iter<'a, T> {}
 
+#[unstable(feature = "trusted_len", issue = "0")]
+unsafe impl<'a, A> TrustedLen for Iter<'a, A> {}
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> Clone for Iter<'a, T> {
     fn clone(&self) -> Iter<'a, T> { Iter { inner: self.inner } }
@@ -924,6 +927,9 @@ impl<'a, T> ExactSizeIterator for IterMut<'a, T> {}
 #[unstable(feature = "fused", issue = "35602")]
 impl<'a, T> FusedIterator for IterMut<'a, T> {}
 
+#[unstable(feature = "trusted_len", issue = "0")]
+unsafe impl<'a, A> TrustedLen for IterMut<'a, A> {}
+
 /// An iterator over the value in a [`Ok`] variant of a [`Result`]. This struct is
 /// created by the [`into_iter`] method on [`Result`][`Result`] (provided by
 /// the [`IntoIterator`] trait).
@@ -961,6 +967,9 @@ impl<T> ExactSizeIterator for IntoIter<T> {}
 #[unstable(feature = "fused", issue = "35602")]
 impl<T> FusedIterator for IntoIter<T> {}
 
+#[unstable(feature = "trusted_len", issue = "0")]
+unsafe impl<A> TrustedLen for IntoIter<A> {}
+
 /////////////////////////////////////////////////////////////////////////////
 // FromIterator
 /////////////////////////////////////////////////////////////////////////////