add map_expect for stream

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/stream/expect.rs

@@ -4,14 +4,19 @@ use crate::Result;
 
 pub trait TryExpect<'a, Item> {
 	fn expect_ok(self) -> impl Stream<Item = Item> + Send + 'a;
+
+	fn map_expect(self, msg: &'a str) -> impl Stream<Item = Item> + Send + 'a;
 }
 
 impl<'a, T, Item> TryExpect<'a, Item> for T
 where
 	T: Stream<Item = Result<Item>> + TryStream + Send + 'a,
+	Item: 'a,
 {
 	#[inline]
-	fn expect_ok(self: T) -> impl Stream<Item = Item> + Send + 'a {
-		self.map(|res| res.expect("stream expectation failure"))
-	}
+	fn expect_ok(self: T) -> impl Stream<Item = Item> + Send + 'a { self.map_expect("stream expectation failure") }
+
+	//TODO: move to impl MapExpect
+	#[inline]
+	fn map_expect(self, msg: &'a str) -> impl Stream<Item = Item> + Send + 'a { self.map(|res| res.expect(msg)) }
 }