Record left-linear expansion and forest format

Now the grammar will record the left-linear expansions when generating
the nondeterministic finite automaton frmo its rules, and will record
whether an edge in the nondeterministic finite automaton comes from a
left-linear expansion.  The latter is needed because while performing
a chain-rule derivation, we do not need the left-linear expanded
derivations in the "first layer".  This might well have been the root
cause of the bad performance of the previous version of this package.

Also I have figured out how to properly generate and handle parse
forests while manipulating the "chain-rule machine".

1 files changed, 2 insertions, 2 deletions

diff --git a/graph/src/builder.rs b/graph/src/builder.rs
index 5505e4f..b04e7f6 100644
--- a/graph/src/builder.rs
+++ b/graph/src/builder.rs
@@ -40,7 +40,7 @@ pub trait Builder: Default {
     /// target should be removed.
     fn remove_edge<F>(&mut self, source: usize, target: usize, predicate: F) -> Result<(), Error>
     where
-        F: Fn(Self::Label) -> bool;
+        F: FnMut(Self::Label) -> bool;
 
     /// Convert the builder into a graph.
     ///
@@ -89,5 +89,5 @@ pub trait BuilderMut {
     /// target should be removed.
     fn remove_edge<F>(&mut self, source: usize, target: usize, predicate: F) -> Result<(), Error>
     where
-        F: Fn(Self::Label) -> bool;
+        F: FnMut(Self::Label) -> bool;
 }