lib/glimmer/dsl/engine.rb in glimmer-1.0.7 vs lib/glimmer/dsl/engine.rb in glimmer-1.0.8

@@ -26,11 +26,11 @@
 
 module Glimmer
   module DSL
     # Glimmer DSL Engine
     #
-    # Follows Interpreter and Chain of Responsibility Design Patterns
+    # Follows Interpreter, Chain of Responsibility, and Singleton Design Patterns
     #
     # When DSL engine interprets an expression, it attempts to handle
     # with ordered expression array specified via `.expressions=` method.
     class Engine
       MESSAGE_NO_DSLS = "Glimmer has no DSLs configured. Add glimmer-dsl-swt gem or visit https://github.com/AndyObtiva/glimmer#multi-dsl-support for more details.\n"
@@ -53,12 +53,12 @@
               interpretation
             else
               raise Glimmer::Error, "Unsupported keyword: #{keyword}" unless static_expression_dsl || retrieved_static_expression
               Glimmer::DSL::Engine.dsl_stack.push(static_expression_dsl || Glimmer::DSL::Engine.dsl)
               static_expression = Glimmer::DSL::Engine.static_expressions[keyword][Glimmer::DSL::Engine.dsl]
-              if !static_expression.can_interpret?(Glimmer::DSL::Engine.parent, keyword, *args, &block)
-                raise Error, "Invalid use of Glimmer keyword #{keyword} with args #{args} under parent #{Glimmer::DSL::Engine.parent}"
+              if static_expression.nil? || !static_expression.can_interpret?(Glimmer::DSL::Engine.parent, keyword, *args, &block)
+                raise Error, "Invalid use of Glimmer keyword #{keyword} with args #{args} under parent #{Glimmer::DSL::Engine.parent.inspect}"
               else
                 Glimmer::Config.logger.info {"#{static_expression.class.name} will handle expression keyword #{keyword}"}
                 Glimmer::DSL::Engine.interpret_expression(static_expression, keyword, *args, &block)
               end
             end
@@ -84,11 +84,11 @@
           dsl_name = dsl_name.to_sym
           disabled_dsls.delete(dsl_name)
         end
 
         def disabled_dsls
-          @disabled_dsls ||= []
+          @disabled_dsls ||= Concurrent::Array.new
         end
 
         def enabled_dsls=(dsl_names)
           dsls.each {|dsl_name| disable_dsl(dsl_name)}
           dsl_names.each {|dsl_name| enable_dsl(dsl_name)}
@@ -107,16 +107,16 @@
           static_expressions.empty? && dynamic_expression_chains_of_responsibility.empty?
         end
 
         # Dynamic expression chains of responsibility indexed by dsl
         def dynamic_expression_chains_of_responsibility
-          @dynamic_expression_chains_of_responsibility ||= {}
+          @dynamic_expression_chains_of_responsibility ||= Concurrent::Hash.new
         end
 
         # Static expressions indexed by keyword and dsl
         def static_expressions
-          @static_expressions ||= {}
+          @static_expressions ||= Concurrent::Hash.new
         end
 
         # Sets dynamic expression chains of responsibility. Useful for internal testing
         attr_writer :dynamic_expression_chains_of_responsibility
 
@@ -145,11 +145,11 @@
 
         def add_static_expression(static_expression)
           Glimmer::Config.logger.info {"Adding static expression: #{static_expression.class.name}"}
           keyword = static_expression.class.keyword
           static_expression_dsl = static_expression.class.dsl
-          static_expressions[keyword] ||= {}
+          static_expressions[keyword] ||= Concurrent::Hash.new
           static_expressions[keyword][static_expression_dsl] = static_expression
           Glimmer.send(:define_method, keyword, &STATIC_EXPRESSION_METHOD_FACTORY.call(keyword))
         end
 
         def expression_class(dsl_namespace, expression_name)
@@ -201,19 +201,19 @@
         # Parents are maintained in a stack while evaluating Glimmer DSL
         # to ensure properly ordered interpretation of DSL syntax
         def_delegator :parent_stack, :last, :parent
 
         def parent_stack
-          parent_stacks[dsl] ||= []
+          parent_stacks[dsl] ||= Concurrent::Array.new
         end
 
         def parent_stacks
-          @parent_stacks ||= {}
+          @parent_stacks ||= Concurrent::Hash.new
         end
 
         # Enables multiple DSLs to play well with each other when mixing together
         def dsl_stack
-          @dsl_stack ||= []
+          @dsl_stack ||= Concurrent::Array.new
         end
       end
     end
   end
 end