Only deep_symbolize_keys when needed

When loading certain translations from file, they can be parsed into their Symbol representation. It is wasteful to traverse the entire object graph in these cases.

lib/i18n/backend/base.rb

@@ -216,34 +216,51 @@ def deep_interpolate(locale, data, values = EMPTY_HASH)
           end
         end
 
+        class LocaleDataDecorator < SimpleDelegator
+          def initialize(*)
+            super
+            @names_symbolized = false
+          end
+
+          def mark_keys_as_symbolized!
+            @names_symbolized = true
+            self
+          end
+
+          def keys_symbolized?
+            @names_symbolized
+          end
+        end
+
         # Loads a single translations file by delegating to #load_rb or
         # #load_yml depending on the file extension and directly merges the
         # data to the existing translations. Raises I18n::UnknownFileType
         # for all other file extensions.
         def load_file(filename)
           type = File.extname(filename).tr('.', '').downcase
           raise UnknownFileType.new(type, filename) unless respond_to?(:"load_#{type}", true)
-          data = send(:"load_#{type}", filename)
-          unless data.is_a?(Hash)
+          locale_data = send(:"load_#{type}", filename)
+          unless locale_data.__getobj__.is_a?(Hash)
             raise InvalidLocaleData.new(filename, 'expects it to return a hash, but does not')
           end
-          data.each { |locale, d| store_translations(locale, d || {}) }
+          locale_data.each { |locale, d| store_translations(locale, d || {}, skip_symbolize_keys: locale_data.keys_symbolized?) }
         end
 
         # Loads a plain Ruby translations file. eval'ing the file must yield
         # a Hash containing translation data with locales as toplevel keys.
         def load_rb(filename)
-          eval(IO.read(filename), binding, filename)
+          translations = eval(IO.read(filename), binding, filename)
+          LocaleDataDecorator.new(translations)
         end
 
         # Loads a YAML translations file. The data must have locales as
         # toplevel keys.
         def load_yml(filename)
           begin
             if YAML.respond_to?(:unsafe_load_file) # Psych 4.0 way
-              YAML.unsafe_load_file(filename)
+              LocaleDataDecorator.new(YAML.unsafe_load_file(filename))
             else
-              YAML.load_file(filename)
+              LocaleDataDecorator.new(YAML.load_file(filename))
             end
           rescue TypeError, ScriptError, StandardError => e
             raise InvalidLocaleData.new(filename, e.inspect)
@@ -255,7 +272,9 @@ def load_yml(filename)
         # toplevel keys.
         def load_json(filename)
           begin
-            ::JSON.parse(File.read(filename), symbolize_names: true, freeze: true)
+            LocaleDataDecorator.new(
+              ::JSON.parse(File.read(filename), symbolize_names: true, freeze: true),
+            ).mark_keys_as_symbolized!
           rescue TypeError, StandardError => e
             raise InvalidLocaleData.new(filename, e.inspect)
           end

lib/i18n/backend/gettext.rb

@@ -43,7 +43,7 @@ def set_comment(msgid_or_sym, comment)
         def load_po(filename)
           locale = ::File.basename(filename, '.po').to_sym
           data = normalize(locale, parse(filename))
-          { locale => data }
+          Backend::Base::LocaleDataDecorator.new({ locale => data })
         end
 
         def parse(filename)

lib/i18n/backend/simple.rb

@@ -40,7 +40,7 @@ def store_translations(locale, data, options = EMPTY_HASH)
           end
           locale = locale.to_sym
           translations[locale] ||= Concurrent::Hash.new
-          data = data.deep_symbolize_keys
+          data = data.deep_symbolize_keys unless options.fetch(:skip_symbolize_keys, false)
           translations[locale].deep_merge!(data)
         end
 

test/backend/simple_test.rb

@@ -140,6 +140,20 @@ def setup
     assert_equal 'foo', I18n.t(:'1')
   end
 
+  test "simple store_translations: store translations doesn't deep symbolize keys if skip_symbolize_keys is true" do
+    data = { :foo => {'bar' => 'barfr', 'baz' => 'bazfr'} }
+
+    # symbolized by default
+    store_translations(:fr, data)
+    assert_equal Hash[:foo, {:bar => 'barfr', :baz => 'bazfr'}], translations[:fr]
+
+    I18n.backend.reload!
+
+    # not deep symbolized when configured
+    store_translations(:fr, data, skip_symbolize_keys: true)
+    assert_equal Hash[:foo, {'bar' => 'barfr', 'baz' => 'bazfr'}], translations[:fr]
+  end
+
   # reloading translations
 
   test "simple reload_translations: unloads translations" do

test/test_helper.rb

@@ -45,8 +45,8 @@ def translations
     I18n.backend.instance_variable_get(:@translations)
   end
 
-  def store_translations(locale, data)
-    I18n.backend.store_translations(locale, data)
+  def store_translations(locale, data, options = I18n::EMPTY_HASH)
+    I18n.backend.store_translations(locale, data, options)
   end
 
   def locales_dir