Add empty bindings and some refactoring

crates/ra_mbe/src/lib.rs

@@ -99,13 +99,31 @@ pub(crate) struct Subtree {
     pub(crate) token_trees: Vec<TokenTree>,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, Eq)]
 pub(crate) enum Separator {
     Literal(tt::Literal),
     Ident(tt::Ident),
     Puncts(SmallVec<[tt::Punct; 3]>),
 }
 
+// Note that when we compare a Separator, we just care about its textual value.
+impl PartialEq for crate::Separator {
+    fn eq(&self, other: &crate::Separator) -> bool {
+        use crate::Separator::*;
+
+        match (self, other) {
+            (Ident(ref a), Ident(ref b)) => a == b,
+            (Literal(ref a), Literal(ref b)) => a == b,
+            (Puncts(ref a), Puncts(ref b)) if a.len() == b.len() => {
+                let a_iter = a.iter().map(|a| a.char);
+                let b_iter = b.iter().map(|b| b.char);
+                a_iter.eq(b_iter)
+            }
+            _ => false,
+        }
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub(crate) struct Repeat {
     pub(crate) subtree: Subtree,