extra reductions

Finished the function of performing extra reductions.

Still untested though.

1 files changed, 30 insertions, 25 deletions

diff --git a/chain/src/default.rs b/chain/src/default.rs
index 6e935fe..1df68b5 100644
--- a/chain/src/default.rs
+++ b/chain/src/default.rs
@@ -214,17 +214,16 @@ pub(crate) struct BoTop {
     top: PaVi,
 }
 
-#[allow(dead_code)]
 impl BoTop {
-    fn new(bottom: PaVi, top: PaVi) -> Self {
+    pub(crate) fn new(bottom: PaVi, top: PaVi) -> Self {
         Self { bottom, top }
     }
 
-    fn top(&self) -> PaVi {
+    pub(crate) fn top(&self) -> PaVi {
         self.top
     }
 
-    fn bottom(&self) -> PaVi {
+    pub(crate) fn bottom(&self) -> PaVi {
         self.bottom
     }
 }
@@ -240,10 +239,10 @@ impl BoTop {
 /// # Reduction format
 ///
 /// The value records a set of tuples of the form `(non-terminal,
-/// rule_position)`.  Such a tuple means we want to reduce from the
-/// expansion of the given `non-terminal`, where the last rule
-/// position we have seen in this branch is the given `rule_position`.
-type Reducer = Map<BoTop, HashSet<(usize, usize)>>;
+/// starting_position)`.  Such a tuple means we want to reduce from
+/// the expansion of the given `non-terminal`, which expands from the
+/// given starting position.  We need to  restrict the
+pub(crate) type Reducer = Map<(usize, usize), HashSet<usize>>;
 
 /// A default implementation for the [`Chain`] trait.
 #[derive(Debug, Clone, Default)]
@@ -553,8 +552,15 @@ impl Chain for DefaultChain {
         ///
         /// The format is as follows:
         ///
-        /// `(graph, atom, accepting_vec, forest_source, new_source)`
-        type GeneratorInput<'a> = (&'a DLGraph<Edge>, &'a DefaultAtom, &'a [bool], PaVi, PaVi);
+        /// `(graph, atom, forest, accepting_vec, forest_source, new_source)`
+        type GeneratorInput<'a> = (
+            &'a DLGraph<Edge>,
+            &'a DefaultAtom,
+            &'a DefaultForest<ForestLabel<GrammarLabel>>,
+            &'a [bool],
+            PaVi,
+            PaVi,
+        );
 
         /// A helper function to generate edges to join.
         ///
@@ -575,7 +581,7 @@ impl Chain for DefaultChain {
         ) -> Result<bool, Error> {
             let mut accepting = false;
 
-            let (graph, atom, accepting_vec, pavi, true_pavi) = input;
+            let (graph, atom, forest, accepting_vec, pavi, true_pavi) = input;
 
             // First check the values from iterators are all valid.
             let graph_len = graph.nodes_len();
@@ -644,21 +650,15 @@ impl Chain for DefaultChain {
 
                             let botop = BoTop::new(true_pavi, new_label.forest_source());
 
-                            let rule_pos = child_label.label().div_euclid(2);
-
-                            let rule_nt = atom
-                                .get_rule_num(rule_pos)
-                                .map_err(index_out_of_bounds_conversion)?;
-
-                            let rule_pos = rule_pos
-                                - atom
-                                    .nth_accumulator(rule_nt)
-                                    .map_err(index_out_of_bounds_conversion)?;
+                            let key = (
+                                forest.node_from_pavi(botop.top())?,
+                                forest.node_from_pavi(botop.bottom)?,
+                            );
 
                             reducer
-                                .entry(botop)
+                                .entry(key)
                                 .or_insert_with(Default::default)
-                                .insert((rule_nt, rule_pos));
+                                .insert(forest.node_from_pavi(new_label.true_source())?);
 
                             output.extend(
                                 std::iter::repeat(new_label.into())
@@ -714,6 +714,7 @@ impl Chain for DefaultChain {
                             }
 
                             new_pavi = self.forest.insert_item(
+                                &self.reducer,
                                 *label,
                                 fragment,
                                 atom_child_iter.clone(),
@@ -735,6 +736,7 @@ impl Chain for DefaultChain {
                         let generator_input = (
                             &self.graph,
                             &self.atom,
+                            &self.forest,
                             self.accepting_vec.as_slice(),
                             new_pavi,
                             new_pavi,
@@ -787,6 +789,7 @@ impl Chain for DefaultChain {
                                 }
 
                                 first_segment_pavi = self.forest.insert_item(
+                                    &self.reducer,
                                     *label,
                                     first_fragment,
                                     atom_child_iter.clone(),
@@ -807,6 +810,7 @@ impl Chain for DefaultChain {
                                 // iterator, in which case the passed
                                 // label is only used for the PaVi.
                                 virtual_pavi = self.forest.insert_item(
+                                    &self.reducer,
                                     Edge::new(0, first_segment_pavi, accepting),
                                     virtual_fragment,
                                     std::iter::empty(),
@@ -828,6 +832,7 @@ impl Chain for DefaultChain {
                             let generator_input = (
                                 &self.graph,
                                 &self.atom,
+                                &self.forest,
                                 self.accepting_vec.as_slice(),
                                 first_segment_pavi,
                                 virtual_pavi,
@@ -980,9 +985,9 @@ impl Chain for DefaultChain {
 
                         for frag in reduction_fragment.into_iter().flatten() {
                             let mut frag = frag.clone();
-                            frag.set_pos(node_label.label().start())?;
+                            frag.set_pos(node_label.label().start(), true)?;
 
-                            stack.push(self.forest.plant_if_needed(*node, frag)?);
+                            stack.push(self.forest.plant_at_start(*node, frag)?);
                         }
                     }
                 }