From 839174a63534a92ee27ec8763c229a1fab84202e Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Fri, 4 Apr 2025 15:24:07 -0400
Subject: [PATCH] Generate comments to annotate reduce table entries

---
 assets/parser.c.erb   | 17 +++++++++++------
 assets/parser.d.erb   | 17 +++++++++++------
 lib/propane/parser.rb |  2 +-
 3 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/assets/parser.c.erb b/assets/parser.c.erb
index ed22631..f95ac75 100644
--- a/assets/parser.c.erb
+++ b/assets/parser.c.erb
@@ -712,17 +712,22 @@ const uint16_t r_<%= rule.name.gsub("$", "_") %><%= rule.id %>_node_field_index_
 /** Parser reduce table. */
 static const reduce_t parser_reduce_table[] = {
 <%   @parser.reduce_table.each do |reduce| %>
-    {<%= reduce[:token_id] %>u, <%= reduce[:rule_id] %>u, <%= reduce[:rule_set_id] %>u, <%= reduce[:n_states] %>u
+    {
+        <%= reduce[:token_id] %>u, /* Token: <%= reduce[:token] ? reduce[:token].name : "(any)" %> */
+        <%= reduce[:rule_id] %>u, /* Rule ID */
+        <%= reduce[:rule_set_id] %>u, /* Rule set ID (<%= reduce[:rule].rule_set.name %>) */
 <%     if @grammar.ast %>
+        <%= reduce[:n_states] %>u, /* Number of states */
 <%       if reduce[:rule].flat_rule_set_node_field_index_map? %>
-             , NULL
+        NULL, /* No rule set node field index map (flat map) */
 <%       else %>
-             , &r_<%= reduce[:rule].name.gsub("$", "_") %><%= reduce[:rule].id %>_node_field_index_map[0]
+        &r_<%= reduce[:rule].name.gsub("$", "_") %><%= reduce[:rule].id %>_node_field_index_map[0], /* Rule set node field index map */
 <%       end %>
-             , <%= reduce[:rule].rule_set.ast_fields.size %>
-             , <%= reduce[:propagate_optional_target] %>
+        <%= reduce[:rule].rule_set.ast_fields.size %>, /* Number of AST fields */
+        <%= reduce[:propagate_optional_target] %>}, /* Propagate optional target? */
+<%     else %>
+        <%= reduce[:n_states] %>u},
 <%     end %>
-    },
 <%   end %>
 };
 
diff --git a/assets/parser.d.erb b/assets/parser.d.erb
index f7abdbc..ee11595 100644
--- a/assets/parser.d.erb
+++ b/assets/parser.d.erb
@@ -875,17 +875,22 @@ immutable ushort[<%= rule.rule_set_node_field_index_map.size %>] r_<%= rule.name
 /** Parser reduce table. */
 private immutable reduce_t[] parser_reduce_table = [
 <%   @parser.reduce_table.each do |reduce| %>
-    reduce_t(<%= reduce[:token_id] %>u, <%= reduce[:rule_id] %>u, <%= reduce[:rule_set_id] %>u, <%= reduce[:n_states] %>u
+    reduce_t(
+        <%= reduce[:token_id] %>u, /* Token: <%= reduce[:token] ? reduce[:token].name : "(any)" %> */
+        <%= reduce[:rule_id] %>u, /* Rule ID */
+        <%= reduce[:rule_set_id] %>u, /* Rule set ID (<%= reduce[:rule].rule_set.name %>) */
 <%     if @grammar.ast %>
+        <%= reduce[:n_states] %>u, /* Number of states */
 <%       if reduce[:rule].flat_rule_set_node_field_index_map? %>
-             , null
+        null, /* No rule set node field index map (flat map) */
 <%       else %>
-             , &r_<%= reduce[:rule].name.gsub("$", "_") %><%= reduce[:rule].id %>_node_field_index_map[0]
+        &r_<%= reduce[:rule].name.gsub("$", "_") %><%= reduce[:rule].id %>_node_field_index_map[0], /* Rule set node field index map */
 <%       end %>
-             , <%= reduce[:rule].rule_set.ast_fields.size %>
-             , <%= reduce[:propagate_optional_target] %>
+        <%= reduce[:rule].rule_set.ast_fields.size %>, /* Number of AST fields */
+        <%= reduce[:propagate_optional_target] %>), /* Propagate optional target? */
+<%     else %>
+        <%= reduce[:n_states] %>u), /* Number of states */
 <%     end %>
-            ),
 <%   end %>
 ];
 
diff --git a/lib/propane/parser.rb b/lib/propane/parser.rb
index 9f7a373..4cf7435 100644
--- a/lib/propane/parser.rb
+++ b/lib/propane/parser.rb
@@ -92,7 +92,7 @@ class Propane
               propagate_optional_target: rule.optional? && rule.components.size == 1}]
           elsif reduce_actions = item_set.reduce_actions
             reduce_actions.map do |token, rule|
-              {token_id: token.id, rule_id: rule.id, rule: rule,
+              {token: token, token_id: token.id, rule_id: rule.id, rule: rule,
                rule_set_id: rule.rule_set.id, n_states: rule.components.size,
                propagate_optional_target: rule.optional? && rule.components.size == 1}
             end