chain: a prototype is added.

I have an ostensibly working prototype now.

Further tests are needed to make sure that the algorithm meets the
time complexity requirement, though.

1 files changed, 7 insertions, 2 deletions

diff --git a/chain/src/atom/mod.rs b/chain/src/atom/mod.rs
index 065640b..398edd2 100644
--- a/chain/src/atom/mod.rs
+++ b/chain/src/atom/mod.rs
@@ -6,17 +6,22 @@
 //! Because this way I can easily substitute other implementations if
 //! I have better ideas in the future.
 
-use grammar::{Error as GrammarError, TNT};
+use grammar::{Error as GrammarError, Grammar, TNT};
 use nfa::{DOption, LabelType, Nfa};
 
+use std::ops::Deref;
+
 /// The expected behaviours of an atomic language.
-pub trait Atom: Nfa<LabelType<TNT>> {
+pub trait Atom: Nfa<LabelType<TNT>> + Deref<Target = Grammar> {
     /// Return the index of a node representing the derivative of the
     /// left-linear null closure of `nt` with respect to `t`.
     fn atom(&self, nt: usize, t: usize) -> Result<Option<usize>, GrammarError>;
 
     /// Return the index of the empty state.
     fn empty(&self) -> usize;
+
+    /// Tell whether a node is accepting.
+    fn is_accepting(&self, node_id: usize) -> Result<bool, GrammarError>;
 }
 
 pub mod default;