--- /dev/null
+use std::iter::Peekable;
+use std::mem;
+use std::ops::Deref;
+
+pub struct Delimited<I: Iterator> {
+ is_first: bool,
+ iter: Peekable<I>,
+}
+
+pub trait IterDelimited: Iterator + Sized {
+ fn delimited(self) -> Delimited<Self> {
+ Delimited { is_first: true, iter: self.peekable() }
+ }
+}
+
+impl<I: Iterator> IterDelimited for I {}
+
+pub struct IteratorItem<T> {
+ value: T,
+ pub is_first: bool,
+ pub is_last: bool,
+}
+
+impl<I: Iterator> Iterator for Delimited<I> {
+ type Item = IteratorItem<I::Item>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ let value = self.iter.next()?;
+ let is_first = mem::replace(&mut self.is_first, false);
+ let is_last = self.iter.peek().is_none();
+ Some(IteratorItem { value, is_first, is_last })
+ }
+}
+
+impl<T> Deref for IteratorItem<T> {
+ type Target = T;
+
+ fn deref(&self) -> &Self::Target {
+ &self.value
+ }
+}