Vendor things

third-party/vendor/swc_common/src/iter.rs

@@ -0,0 +1,45 @@
+/// Copied from https://users.rust-lang.org/t/iterator-need-to-identify-the-last-element/8836/3
+pub trait IdentifyLast: Iterator + Sized {
+    fn identify_last(self) -> Iter<Self>;
+}
+
+impl<It> IdentifyLast for It
+where
+    It: Iterator,
+{
+    fn identify_last(mut self) -> Iter<Self> {
+        let e = self.next();
+        Iter {
+            iter: self,
+            buffer: e,
+        }
+    }
+}
+
+pub struct Iter<It>
+where
+    It: Iterator,
+{
+    iter: It,
+    buffer: Option<It::Item>,
+}
+
+impl<It> Iterator for Iter<It>
+where
+    It: Iterator,
+{
+    type Item = (bool, It::Item);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self.buffer.take() {
+            None => None,
+            Some(e) => match self.iter.next() {
+                None => Some((true, e)),
+                Some(f) => {
+                    self.buffer = Some(f);
+                    Some((false, e))
+                }
+            },
+        }
+    }
+}