re-organize the iterator module a bit

src/libcore/iterator.rs

@@ -22,11 +22,11 @@ pub trait IteratorUtil<A> {
     // FIXME: #5898: should be called map
     fn transform<'r, B>(self, f: &'r fn(A) -> B) -> MapIterator<'r, A, B, Self>;
     fn filter<'r>(self, predicate: &'r fn(&A) -> bool) -> FilterIterator<'r, A, Self>;
+    fn enumerate(self) -> EnumerateIterator<Self>;
     fn skip_while<'r>(self, predicate: &'r fn(&A) -> bool) -> SkipWhileIterator<'r, A, Self>;
     fn take_while<'r>(self, predicate: &'r fn(&A) -> bool) -> TakeWhileIterator<'r, A, Self>;
     fn skip(self, n: uint) -> SkipIterator<Self>;
     fn take(self, n: uint) -> TakeIterator<Self>;
-    fn enumerate(self) -> EnumerateIterator<Self>;
     fn advance(&mut self, f: &fn(A) -> bool);
 }
 
@@ -101,6 +101,21 @@ impl<A, B, T: Iterator<A>, U: Iterator<B>> Iterator<(A, B)> for ZipIterator<T, U
     }
 }
 
+pub struct MapIterator<'self, A, B, T> {
+    priv iter: T,
+    priv f: &'self fn(A) -> B
+}
+
+impl<'self, A, B, T: Iterator<A>> Iterator<B> for MapIterator<'self, A, B, T> {
+    #[inline]
+    fn next(&mut self) -> Option<B> {
+        match self.iter.next() {
+            Some(a) => Some((self.f)(a)),
+            _ => None
+        }
+    }
+}
+
 pub struct FilterIterator<'self, A, T> {
     priv iter: T,
     priv predicate: &'self fn(&A) -> bool
@@ -120,21 +135,6 @@ impl<'self, A, T: Iterator<A>> Iterator<A> for FilterIterator<'self, A, T> {
     }
 }
 
-pub struct MapIterator<'self, A, B, T> {
-    priv iter: T,
-    priv f: &'self fn(A) -> B
-}
-
-impl<'self, A, B, T: Iterator<A>> Iterator<B> for MapIterator<'self, A, B, T> {
-    #[inline]
-    fn next(&mut self) -> Option<B> {
-        match self.iter.next() {
-            Some(a) => Some((self.f)(a)),
-            _ => None
-        }
-    }
-}
-
 pub struct EnumerateIterator<T> {
     priv iter: T,
     priv count: uint