forest: clone correctly

Now the forest can detect if a node is packed or cloned, and correctly
clones a node in those circumstances.  But it still needs to be
tested.

1 files changed, 4 insertions, 4 deletions

diff --git a/chain/src/lib.rs b/chain/src/lib.rs
index 91c37f7..a3d420b 100644
--- a/chain/src/lib.rs
+++ b/chain/src/lib.rs
@@ -131,6 +131,7 @@ where
                         Ok(new) => new,
                         Err(error) => {
                             // Prevent further iterations.
+                            self.stop = true;
 
                             return Some(Err(error.into()));
                         }
@@ -157,8 +158,7 @@ pub trait Chain: LabelExtGraph<Edge> {
 
     /// Represents the language that is present after we parse the
     /// empty string, that is the initial configuration of the
-    /// language.  This may or may not be different from what
-    /// `Default::default` gives.
+    /// language.
     fn unit(atom: Self::Atom) -> Result<Self, Self::Error>;
 
     /// Return true if and only if the language contains the empty
@@ -171,7 +171,7 @@ pub trait Chain: LabelExtGraph<Edge> {
     /// An iterator that iterates all layers that need to be merged.
     type DerIter: Iterator<Item = TwoLayers>;
 
-    /// Take the derivative by a terminal symbol at position `POS`.
+    /// Take the derivative by a terminal `t` at position `pos`.
     fn derive(&mut self, t: usize, pos: usize) -> Result<Self::DerIter, Self::Error>;
 
     /// Take the union of all derivatives.
@@ -187,7 +187,7 @@ pub trait Chain: LabelExtGraph<Edge> {
 
         let edges = self.union(der_iter)?;
 
-        let new_index = self.extend(edges.into_iter())?;
+        let new_index = self.extend(edges)?;
 
         self.update_history(new_index);