move value into its own folder

crates/nu-protocol/src/value/stream.rs

@@ -0,0 +1,50 @@
+use crate::*;
+use std::{cell::RefCell, fmt::Debug, rc::Rc};
+
+#[derive(Clone)]
+pub struct ValueStream(pub Rc<RefCell<dyn Iterator<Item = Value>>>);
+
+impl ValueStream {
+    pub fn into_string(self) -> String {
+        format!(
+            "[{}]",
+            self.map(|x: Value| x.into_string())
+                .collect::<Vec<String>>()
+                .join(", ")
+        )
+    }
+
+    pub fn from_stream(input: impl Iterator<Item = Value> + 'static) -> ValueStream {
+        ValueStream(Rc::new(RefCell::new(input)))
+    }
+}
+
+impl Debug for ValueStream {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("ValueStream").finish()
+    }
+}
+
+impl Iterator for ValueStream {
+    type Item = Value;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        {
+            let mut iter = self.0.borrow_mut();
+            iter.next()
+        }
+    }
+}
+
+pub trait IntoValueStream {
+    fn into_value_stream(self) -> ValueStream;
+}
+
+impl<T> IntoValueStream for T
+where
+    T: Iterator<Item = Value> + 'static,
+{
+    fn into_value_stream(self) -> ValueStream {
+        ValueStream::from_stream(self)
+    }
+}