group into is generic

src/ext.rs

@@ -18,11 +18,11 @@ use tokio::{
 use futures::future::Future;
 
 #[derive(Debug)]
-pub struct GroupIter<I, T>(std::iter::Fuse<I>, Vec<T>, usize);
+pub struct GroupIter<I, T, U=Box<[T]>>(std::iter::Fuse<I>, Vec<T>, usize, PhantomData<U>);
 
-impl<I: Iterator<Item=T>, T> Iterator for GroupIter<I, T>
+impl<U: From<Vec<T>>, I: Iterator<Item=T>, T> Iterator for GroupIter<I, T, U>
 {
-    type Item = Box<[T]>;
+    type Item = U;
     fn next(&mut self) -> Option<Self::Item>
     {
 	if self.1.len() == 0 {
@@ -48,18 +48,39 @@ impl<I: Iterator<Item=T>, T> std::iter::FusedIterator for GroupIter<I, T>{}
 
 pub trait GroupIterExt<I, T>: Sized
 {
+    /// Group this iterator to return a constructed `U` of every `n` items.
+    ///
+    /// # Notes
+    /// If there isn't `n` items left in the iterator, then the rest is returned.
+    fn group_into<U>(self, n: usize) -> GroupIter<I, T, U>
+    where U: From<Vec<T>>;
+
+    
+    /// Group this iterator to return a `Vec<T>` of every `n` items.
+    ///
+    /// # Notes
+    /// If there isn't `n` items left in the iterator, then the rest is returned.
+    #[inline] fn group(self, n: usize) -> GroupIter<I, T, Vec<T>>
+    {
+	self.group_into(n)
+    }
+    
     /// Group this iterator to return a boxed slice of every `n` items.
     ///
     /// # Notes
     /// If there isn't `n` items left in the iterator, then the rest is returned.
-    fn group(self, n: usize) -> GroupIter<I, T>;
+    #[inline] fn group_into_boxed_slice(self, n: usize) -> GroupIter<I, T>
+    {
+	self.group_into(n)
+    }
 }
 
 impl<T: IntoIterator> GroupIterExt<<T as IntoIterator>::IntoIter, <T as IntoIterator>::Item> for T
 {
-    fn group(self, every: usize) -> GroupIter<<T as IntoIterator>::IntoIter, <T as IntoIterator>::Item>
+    fn group_into<U>(self, every: usize) -> GroupIter<<T as IntoIterator>::IntoIter, <T as IntoIterator>::Item, U>
+	where U: From<Vec<<T as IntoIterator>::Item>>
     {
-	GroupIter(self.into_iter().fuse(), Vec::with_capacity(every), every)
+	GroupIter(self.into_iter().fuse(), Vec::with_capacity(every), every, PhantomData)
     }
 }