better, correcter use of return storage

lib/ast/basic_expressions.rb

@@ -2,10 +2,18 @@
 
 module Ast
 
+  # Constant expressions can by definition be evaluated at compile time.
+  # But that does not solve their storage, ie they need to be accessible at runtime from _somewhere_
+  # So we view ConstantExpressions like functions that return the value of the constant.
+  # In other words, their storage is the return slot as it would be for a method
+
+  # The current approach moves the constant into a varaible before using it
+  # But in the future (in the one that holds great things) we optimize those unneccesay moves away
+  
   class IntegerExpression < Expression
 #    attr_reader :value
     def compile method , message
-      to = Virtual::Return.new(Virtual::Integer)
+      to = Virtual::NewReturn.new(Virtual::Integer)
       method.add_code Virtual::Set.new( to , Virtual::IntegerConstant.new(value))
       to
     end
@@ -13,19 +21,25 @@ module Ast
 
   class TrueExpression
     def compile method , message
-      Virtual::TrueValue.new
+      to = Virtual::Return.new(Virtual::Reference)
+      method.add_code Virtual::Set.new( to , Virtual::TrueConstant.new )
+      to
     end
   end
   
   class FalseExpression
     def compile method , message
-      Virtual::FalseValue.new
+      to = Virtual::Return.new(Virtual::Reference)
+      method.add_code Virtual::Set.new( to , Virtual::FalseConstant.new )
+      to
     end
   end
   
   class NilExpression
     def compile method , message
-      Virtual::NilValue.new
+      to = Virtual::Return.new(Virtual::Reference)
+      method.add_code Virtual::Set.new( to , Virtual::NilConstant.new )
+      to
     end
   end
 
@@ -49,20 +63,22 @@ module Ast
   class ModuleName < NameExpression
 
     def compile method , message
+      to = Virtual::Return.new(Virtual::Reference)
       clazz = ::Virtual::BootSpace.space.get_or_create_class name
       raise "uups #{clazz}.#{name}" unless clazz
-      #class qualifier, means call from metaclass
-      #clazz = clazz.meta_class
-      clazz
+      method.add_code Virtual::Set.new( to , clazz )
+      to
     end    
   end
 
   class StringExpression < Expression
 #    attr_reader  :string
     def compile method , message
+      to = Virtual::Return.new(Virtual::Reference)
       value = Virtual::StringConstant.new(string)
-      ::Virtual::BootSpace.space.add_object value 
-      value
+      Virtual::BootSpace.space.add_object value 
+      method.add_code Virtual::Set.new( to , value )
+      to
     end
   end
   class AssignmentExpression < Expression
@@ -74,32 +90,12 @@ module Ast
       raise "oh noo, nil from where #{right.inspect}" unless r
       message.compile_set( method , left.name , r )
     end
-    def old_scratch
-      if operator == "="    # assignment, value based
-        if(left.is_a? VariableExpression)
-          left.make_setter
-          l_val = left.compile(context)
-        elsif left.is_a?(NameExpression)
-          puts context.inspect unless context.locals
-          l_val = context.locals[left.name]
-          if( l_val ) #variable existed, move data there
-            l_val = l_val.move( into , r_val) 
-          else
-            l_val = context.function.new_local.move( into , r_val )
-          end
-          context.locals[left.name] = l_val
-        else
-          raise "Can only assign variables, not #{left}" 
-        end
-        return l_val
-      end
-    end
   end
 
   class VariableExpression < NameExpression
     def compile method , message
       method.add_code Virtual::InstanceGet.new(name)
-      Virtual::Return.new( Virtual::Mystery )
+      Virtual::NewReturn.new( Virtual::Mystery )
     end
   end
 end

lib/ast/call_site_expression.rb

@@ -10,56 +10,17 @@ module Ast
       method.add_code Virtual::Set.new(Virtual::NewName.new(), name)
       compiled_args = []
       args.each_with_index do |arg , i|
-        val = arg.compile( method, message) #compile in the running method, ie before passing control
+        #compile in the running method, ie before passing control
+        val = arg.compile( method, message) 
         compiled_args << val
+        # move the compiled value to it's slot in the new message
+        # (doing this immediately, not after the loop, so if it's a return it won't get overwritten)
         method.add_code Virtual::Set.new(Virtual::NewMessageSlot.new(i ,val.type ) , val )
       end
       method.add_code Virtual::MessageSend.new(name , me , compiled_args) #and pass control
-      Virtual::Return.new( method.return_type )
+      # the effect of the method is that the NewMessage Return slot will be filled, return it
+      # (this is what is moved _inside_ above loop for such expressions that are calls (or constants))
+      Virtual::NewReturn.new( method.return_type )
     end
-
-    def scratch
-      into = context.function
-      params = args.collect{ |a| a.compile(context) }
-      puts "compiling receiver #{receiver} (call #{name})"
-      if receiver.is_a? ModuleName
-        clazz = context.object_space.get_or_create_class receiver.name
-        value_receiver = clazz.meta_class
-        function = value_receiver.resolve_method name
-      elsif receiver.is_a?(StringExpression) or receiver.is_a?(IntegerExpression)
-        #TODO obviously the class is wrong, but you gotta start somewhere
-        clazz = context.object_space.get_or_create_class :Object
-        function = clazz.resolve_method name
-        value_receiver = receiver.compile(context)
-      elsif receiver.is_a?(NameExpression) 
-        if(receiver.name == :self)
-          function = context.current_class.resolve_method(name)
-          value_receiver = Virtual::Integer.new(Virtual::RegisterMachine.instance.receiver_register)
-        else
-          value_receiver = receiver.compile(context)
-          # TODO HACK warning: should determine class dynamically
-          function = context.current_class.resolve_method(name)
-        end
-      elsif receiver.is_a? VariableExpression
-        value_receiver = receiver.compile(context)
-        function = context.current_class.resolve_method(name)
-      else
-        #This , how does one say nowadays, smells. Smells of unused polymorphism actually
-        raise "Not sure this is possible, but never good to leave elses open #{receiver} #{receiver.class}"
-      end
-      raise "No such method error #{inspect}" if (function.nil?)
-      raise "No receiver error #{inspect}:#{receiver}" if (value_receiver.nil?)
-      call = Virtual::CallSite.new( name ,  value_receiver , params  , function)
-      current_function = context.function
-      into.push([])  unless current_function.nil?
-      call.load_args into
-      call.do_call into
-      
-      after = into.new_block("#{name}#{@@counter+=1}")
-      into.current after
-      into.pop([]) unless current_function.nil?
-      function.return_type
-    end
-  end
-  
+  end  
 end

lib/ast/module_expression.rb

@@ -2,18 +2,6 @@ module Ast
   class ModuleExpression < Expression
 #    attr_reader  :name ,:expressions
     def compile context
-      clazz = context.object_space.get_or_create_class name
-      puts "Created class #{clazz.name.inspect}"
-      context.current_class = clazz
-      expressions.each do |expression|
-        # check if it's a function definition and add
-        # if not, execute it, but that does means we should be in salama (executable), not ruby. ie throw an error for now
-        raise "only functions for now #{expression.inspect}" unless expression.is_a? Ast::FunctionExpression
-        puts "compiling expression #{expression}"
-        expression_value = expression.compile(context )
-        #puts "compiled expression #{expression_value.inspect}"
-      end
-
       return clazz
     end
   end
@@ -22,7 +10,6 @@ module Ast
     def compile method , message
       clazz = ::Virtual::BootSpace.space.get_or_create_class name
       puts "Created class #{clazz.name.inspect}"
-#      context.current_class = clazz
       expressions.each do |expression|
         # check if it's a function definition and add
         # if not, execute it, but that does means we should be in salama (executable), not ruby. ie throw an error for now