Finally produced the first correct forest

Finally the prototype parser has produced the first correct forest.
It is my first time to generate a correct forest, in fact, ever since
the beginning of this project.

1 files changed, 15 insertions, 4 deletions

diff --git a/chain/src/atom/default.rs b/chain/src/atom/default.rs
index e88cfc9..9c91296 100644
--- a/chain/src/atom/default.rs
+++ b/chain/src/atom/default.rs
@@ -48,18 +48,31 @@ pub struct DefaultAtom {
 impl DefaultAtom {
     /// Return the string description of a rule position.
     pub fn rule_pos_string(&self, pos: usize) -> Result<String, Box<dyn std::error::Error>> {
+        if pos == self.grammar.total() {
+            return Ok("End of rules".to_owned());
+        }
+
         let rule_num = self.grammar.get_rule_num(pos)?;
 
         assert!(rule_num < self.grammar.non_num());
 
-        let display_tnt = |tnt| self.name_of_tnt(tnt).unwrap_or_else(|e| format!("{e}"));
+        let display_tnt = |tnt| {
+            format!(
+                " {} ",
+                self.name_of_tnt(match tnt {
+                    TNT::Non(_) => tnt,
+                    TNT::Ter(t) => self.unpack_tnt(t).unwrap(),
+                })
+                .unwrap_or_else(|e| format!("{e}"))
+            )
+        };
 
         Ok(self.regexp.get(rule_num).unwrap().to_string_with_dot(
             display_tnt,
             if rule_num == 0 {
                 pos
             } else {
-                pos - self.grammar.nth_accumulator(rule_num - 1)?
+                pos - self.grammar.nth_accumulator(rule_num)?
             },
         )?)
     }
@@ -394,8 +407,6 @@ impl DefaultAtom {
             }
         }
 
-        // dbg!(&accumulators);
-
         for nt in 0..nt_num {
             let children: std::collections::HashMap<_, _> = nfa
                 // This is safe because of the above assertion.