Refactor Parser::Ruby#call_node_name_arguments

Arguably, these methods belong more to the visitor than the "scanner".
Since they simply process prism nodes without any ivar references, they
should probably be converted into module functions on a utility module.

Author: nevans

lib/rdoc/parser/ruby.rb

@@ -389,15 +389,23 @@ def handle_modifier_directive(code_object, line_no) # :nodoc:
   end
 
   def call_node_name_arguments(call_node) # :nodoc:
-    return [] unless call_node.arguments
-    call_node.arguments.arguments.map do |arg|
-      case arg
-      when Prism::SymbolNode
-        arg.value
-      when Prism::StringNode
-        arg.unescaped
-      end
-    end || []
+    return unless arguments_node = call_node.arguments
+    names = arguments_node.arguments.filter_map { |arg| argument_name(arg) }
+    names unless names.empty?
+  end
+
+  def call_node_name_argument(call_node) # :nodoc:
+    return unless call_node.arguments
+    argument_name(call_node.arguments.arguments.first)
+  end
+
+  def argument_name(argument_node) # :nodoc:
+    case argument_node
+    when Prism::SymbolNode
+      argument_node.value
+    when Prism::StringNode
+      argument_node.unescaped
+    end
   end
 
   # Handles meta method comments
@@ -413,7 +421,7 @@ def handle_meta_method_comment(comment, directives, node)
       case directive
       when 'attr', 'attr_reader', 'attr_writer', 'attr_accessor'
         attributes = [param] if param
-        attributes ||= call_node_name_arguments(node).compact if is_call_node
+        attributes ||= call_node_name_arguments(node) if is_call_node
         rw = directive == 'attr_writer' ? 'W' : directive == 'attr_accessor' ? 'RW' : 'R'
       when 'method'
         method_name = param if param
@@ -439,7 +447,7 @@ def handle_meta_method_comment(comment, directives, node)
         mark_container_documentable(@container)
       end
     elsif line_no || node
-      method_name ||= call_node_name_arguments(node).first if is_call_node
+      method_name ||= call_node_name_argument(node) if is_call_node
       if node
         tokens = syntax_highlighted_tokens(node)
         line_no = node.location.start_line
@@ -1233,8 +1241,7 @@ def constant_arguments_names(call_node)
     end
 
     def call_node_name_arguments(call_node)
-      names = @scanner.call_node_name_arguments(call_node).compact
-      names unless names.empty?
+      @scanner.call_node_name_arguments(call_node)
     end
 
     def symbol_arguments(call_node)