1 files changed, 7 insertions, 16 deletions
diff --git a/chain/src/default.rs b/chain/src/default.rs
index b9d7fe6..22befff 100644
--- a/chain/src/default.rs
+++ b/chain/src/default.rs
@@ -10,10 +10,7 @@ use crate::atom::{Atom, DefaultAtom};
 use core::fmt::Display;
 use forest::{default::DefaultForest, Forest};
 use grammar::{Error as GrammarError, GrammarLabel, GrammarLabelType, TNT};
-#[allow(unused_imports)]
-use graph::{
-    labelled::DLGBuilder, Builder, DLGraph, Graph, LabelExtGraph, LabelGraph, ParentsGraph,
-};
+use graph::{labelled::DLGBuilder, Builder, DLGraph, Graph, LabelExtGraph, LabelGraph};
 
 use std::collections::{HashMap as Map, TryReserveError};
 
@@ -156,11 +153,13 @@ impl Iterator for DerIter {
                         None
                     }
                 } else {
-                    self.index = DerIterIndex::Single(0);
+                    // If the zero-th element is present, we will
+                    // advance the index to one; if it is not present,
+                    // we will stop iteration.  In each case we can
+                    // safely set the index to one.
+                    self.index = DerIterIndex::Single(1);
 
                     if let Some((edge, to)) = self.singles.first() {
-                        self.index = DerIterIndex::Single(1);
-
                         Some(TwoLayers::One(*edge, *to))
                     } else {
                         None
@@ -776,15 +775,7 @@ mod test_chain {
 
         println!("repeating {repeat_times} times");
 
-        let input = {
-            let mut result = Vec::with_capacity(input_template.len() * repeat_times);
-
-            for _ in 0..repeat_times {
-                result.extend(input_template.iter().copied());
-            }
-
-            result
-        };
+        let input = input_template.repeat(repeat_times);
 
         let start = std::time::Instant::now();