Update range_trie.rs

Author: chris-ha458

regex-automata/src/nfa/thompson/range_trie.rs

@@ -235,7 +235,7 @@ impl RangeTrie {
     /// Clear this range trie such that it is empty. Clearing a range trie
     /// and reusing it can beneficial because this may reuse allocations.
     pub fn clear(&mut self) {
-        self.free.extend(self.states.drain(..));
+        self.free.append(&mut self.states);
         self.add_empty(); // final
         self.add_empty(); // root
     }
@@ -296,7 +296,7 @@ impl RangeTrie {
         assert!(!ranges.is_empty());
         assert!(ranges.len() <= 4);
 
-        let mut stack = mem::replace(&mut self.insert_stack, vec![]);
+        let mut stack = std::mem::take(&mut self.insert_stack);
         stack.clear();
 
         stack.push(NextInsert::new(ROOT, ranges));
@@ -866,7 +866,7 @@ impl Split {
 
 impl fmt::Debug for RangeTrie {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        writeln!(f, "")?;
+        writeln!(f)?;
         for (i, state) in self.states.iter().enumerate() {
             let status = if i == FINAL.as_usize() { '*' } else { ' ' };
             writeln!(f, "{}{:06}: {:?}", status, i, state)?;