Implement nested lists

lib/notare/builder.rb

@@ -93,12 +93,10 @@ module Notare
     end
 
     def li(text = nil, &block)
-      item = Nodes::ListItem.new([], list_type: @current_list.type, num_id: @current_list.num_id)
-      if block
-        with_target(item, &block)
-      elsif text
-        item.add_run(Nodes::Run.new(text, **current_formatting))
-      end
+      current_type = @list_type_stack.last
+      item = Nodes::ListItem.new([], list_type: current_type, num_id: @current_list.num_id, level: @list_level)
+      item.add_run(Nodes::Run.new(text, **current_formatting)) if text
+      with_target(item, &block) if block
       @current_list.add_item(item)
     end
 
@@ -134,15 +132,31 @@ module Notare
 
     def list(type, &block)
       @num_id_counter ||= 0
-      @num_id_counter += 1
-      mark_has_lists!
+      @list_level ||= 0
+      @list_type_stack ||= []
 
-      list_node = Nodes::List.new(type: type, num_id: @num_id_counter)
       previous_list = @current_list
-      @current_list = list_node
-      block.call
-      @current_list = previous_list
-      @nodes << list_node
+      nested = !previous_list.nil?
+
+      if nested
+        # Nested list: reuse parent list, push new type, increment level
+        @list_level += 1
+        @list_type_stack.push(type)
+        block.call
+        @list_type_stack.pop
+        @list_level -= 1
+      else
+        # Top-level list: new List node
+        @num_id_counter += 1
+        mark_has_lists!
+        list_node = Nodes::List.new(type: type, num_id: @num_id_counter)
+        @list_type_stack.push(type)
+        @current_list = list_node
+        block.call
+        @current_list = previous_list
+        @list_type_stack.pop
+        @nodes << list_node
+      end
     end
 
     def with_format(format, &block)