display attribute for Math tag

lib/mml/math_with_namespace.rb

@@ -8,13 +8,17 @@ class MathWithNamespace < Lutaml::Model::Serializable
       attribute :"#{tag}_value", Mml.const_get(tag.capitalize), collection: true
     end
 
+    attribute :display, :string
+
     xml do
       root "math", mixed: true
       namespace "http://www.w3.org/1998/Math/MathML", nil
 
       Mml::Configuration::SUPPORTED_TAGS.each do |tag|
         map_element tag.to_sym, to: :"#{tag}_value"
       end
+
+      map_attribute :display, to: :display
     end
   end
 end

lib/mml/math_with_nil_namespace.rb

@@ -8,12 +8,16 @@ class MathWithNilNamespace < Lutaml::Model::Serializable
       attribute :"#{tag}_value", Mml.const_get(tag.capitalize), collection: true
     end
 
+    attribute :display, :string
+
     xml do
       root "math", mixed: true
 
       Mml::Configuration::SUPPORTED_TAGS.each do |tag|
         map_element tag.to_sym, to: :"#{tag}_value"
       end
+
+      map_attribute :display, to: :display
     end
   end
 end

lib/mml/mml.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-DEFAULT_ADAPTER = if RUBY_VERSION == "opal"
+DEFAULT_ADAPTER = if RUBY_ENGINE == "opal"
                     require "lutaml/model/xml_adapter/oga_adapter"
                     :oga
                   else

lib/mml/mn.rb

@@ -4,7 +4,7 @@ module Mml
   class Mn < Lutaml::Model::Serializable
     model Mml::Configuration.class_for(:mn)
 
-    attribute :value, :integer
+    attribute :value, :string
     attribute :mathcolor, :string
     attribute :mathbackground, :string
     attribute :mathvariant, :string

mml.gemspec

@@ -30,6 +30,6 @@ Gem::Specification.new do |spec|
   spec.executables = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_runtime_dependency "lutaml-model", "~> 0.3"
+  spec.add_runtime_dependency "lutaml-model", "~> 0.5"
   spec.add_runtime_dependency "zeitwerk"
 end

spec/fixtures/with_namespace/example_1.mml

@@ -1,4 +1,4 @@
-<math xmlns="http://www.w3.org/1998/Math/MathML">
+<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
   <mrow>
     <mi>i</mi>
     <mo>+</mo>

spec/fixtures/without_namespace/example_1.mml

@@ -1,4 +1,4 @@
-<math>
+<math display="block">
   <mrow>
     <mi>i</mi>
     <mo>+</mo>