From 66c2adda209c17ef05c63dd2e461db01bec7f20e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Torsten=20R=C3=BCger?= <torsten@webdev.camp>
Date: Tue, 6 Aug 2019 18:33:27 +0300
Subject: [PATCH] Copy risc compiler stuff to mom

Start to separate the layers.
wip, just checkin in to see the following changes better
---
 lib/mom/block_compiler.rb          | 53 ++++++++++++++++++
 lib/mom/callable_compiler.rb       | 52 ++++++++++--------
 lib/mom/method_compiler.rb         | 85 +++++++++++++++++++++++++++++
 lib/mom/mom_collection.rb          | 86 ++++++++++++++++++++++++++++++
 lib/parfait/block.rb               |  4 +-
 lib/parfait/type.rb                | 22 ++++----
 lib/parfait/vool_method.rb         |  2 +-
 lib/risc/builder.rb                |  6 +++
 lib/risc/method_compiler.rb        |  5 +-
 lib/vool/class_method_statement.rb |  1 +
 lib/vool/class_statement.rb        |  2 +-
 test/mom/test_block_compiler.rb    | 85 +++++++++++++++++++++++++++++
 test/mom/test_method_compiler.rb   | 40 ++++++++++++++
 test/mom/test_mom_collection.rb    | 40 ++++++++++++++
 test/support/compiling.rb          | 44 +++++++--------
 test/vool/test_class_statement.rb  | 29 ++++++++++
 16 files changed, 492 insertions(+), 64 deletions(-)
 create mode 100644 lib/mom/block_compiler.rb
 create mode 100644 lib/mom/method_compiler.rb
 create mode 100644 lib/mom/mom_collection.rb
 create mode 100644 test/mom/test_block_compiler.rb
 create mode 100644 test/mom/test_method_compiler.rb
 create mode 100644 test/mom/test_mom_collection.rb
 create mode 100644 test/vool/test_class_statement.rb

diff --git a/lib/mom/block_compiler.rb b/lib/mom/block_compiler.rb
new file mode 100644
index 00000000..350cb120
--- /dev/null
+++ b/lib/mom/block_compiler.rb
@@ -0,0 +1,53 @@
+module Mom
+
+  # A BlockCompiler is much like a MehtodCompiler, exept for blocks
+  #
+  class BlockCompiler < CallableCompiler
+
+    attr_reader :block , :risc_instructions , :constants
+    alias :block  :callable
+
+    def initialize( block , method)
+      @method = method
+      super(block)
+    end
+
+    def source_name
+      "#{@method.self_type.name}.init"
+    end
+
+    # resolve the type of the slot, by inferring from it's name, using the type
+    # scope related slots are resolved by the compiler by method/block
+    #
+    # This mainly calls super, and only for :caller adds extra info
+    # Using the info, means assuming that the block is not passed around (FIXME in 2020)
+    def slot_type( slot , type)
+      new_type = super
+      if slot == :caller
+        extra_info = { type_frame: @method.frame_type ,
+                       type_arguments: @method.arguments_type ,
+                       type_self: @method.self_type}
+      end
+      return new_type , extra_info
+    end
+    # determine how given name need to be accsessed.
+    # For blocks the options are args or frame
+    # or then the methods arg or frame
+    def slot_type_for(name)
+      if @callable.arguments_type.variable_index(name)
+        slot_def = [:arguments]
+      elsif @callable.frame_type.variable_index(name)
+        slot_def = [:frame]
+      elsif @method.arguments_type.variable_index(name)
+        slot_def = [:caller , :caller ,:arguments ]
+      elsif @method.frame_type.variable_index(name)
+        slot_def = [:caller ,:caller , :frame ]
+      elsif
+        raise "no variable #{name} , need to resolve at runtime"
+      end
+      slot_def << name
+    end
+
+
+  end
+end
diff --git a/lib/mom/callable_compiler.rb b/lib/mom/callable_compiler.rb
index 352e8a55..e710d9ab 100644
--- a/lib/mom/callable_compiler.rb
+++ b/lib/mom/callable_compiler.rb
@@ -1,8 +1,10 @@
 module Mom
 
-  # CallableCompiler is used to generate Mom instructions.
+  # CallableCompiler is used to generate mom instructions. It is an abstact base
+  # class shared by BlockCompiler and MethodCompiler
 
-  # - mom_instructions: The sequence of mom level instructions that vool was compiled to
+  # - mom_instructions: The sequence of mom level instructions that mom was compiled to
+  #                 Instructions derive from class Instruction and form a linked list
 
   class CallableCompiler
 
@@ -10,11 +12,11 @@ module Mom
       @callable = callable
       @constants = []
       @block_compilers = []
-      @mom_instructions = Risc.label(source_name, source_name)
+      @mom_instructions = Label.new(source_name, source_name)
       @current = start = @risc_instructions
-      add_code Risc.label( source_name, "return_label")
-      Mom::ReturnSequence.new.to_risc(self)
-      add_code Risc.label( source_name, "unreachable")
+      add_code Label.new( source_name, "return_label")
+      add_code Mom::ReturnSequence.new
+      add_code Label.new( source_name, "unreachable")
       @current = start
     end
     attr_reader :risc_instructions , :constants , :block_compilers , :callable , :current
@@ -26,20 +28,6 @@ module Mom
       end
     end
 
-    # convert the given mom instruction to_risc and then add it (see add_code)
-    # continue down the instruction chain unti depleted
-    # (adding moves the insertion point so the whole mom chain is added as a risc chain)
-    def add_mom( instruction )
-      while( instruction )
-        raise "whats this a #{instruction}" unless instruction.is_a?(Mom::Instruction)
-        #puts "adding mom #{instruction.to_s}:#{instruction.next.to_s}"
-        instruction.to_risc( self )
-        reset_regs
-        #puts "adding risc #{risc.to_s}:#{risc.next.to_s}"
-        instruction = instruction.next
-      end
-    end
-
     # add a constant (which get created during compilation and need to be linked)
     def add_constant(const)
       raise "Must be Parfait #{const}" unless const.is_a?(Parfait::Object)
@@ -49,18 +37,38 @@ module Mom
     # add a risc instruction after the current (insertion point)
     # the added instruction will become the new insertion point
     def add_code( instruction )
-      raise "Not an instruction:#{instruction.to_s}:#{instruction.class.name}" unless  instruction.is_a?(Risc::Instruction)
-      raise instruction.to_s if( instruction.class.name.split("::").first == "Arm")
+      raise "Not an instruction:#{instruction.to_s}:#{instruction.class.name}" unless  instruction.is_a?(Mom::Instruction)
       new_current = instruction.last #after insertion this point is lost
       @current.insert(instruction) #insert after current
       @current = new_current
       self
     end
 
+    # resolve the type of the slot, by inferring from it's name, using the type
+    # scope related slots are resolved by the compiler by method/block
+    def slot_type( slot , type)
+      case slot
+      when :frame
+        new_type = self.frame_type
+      when :arguments
+        new_type = self.arg_type
+      when :receiver
+        new_type = self.receiver_type
+      when Symbol
+        new_type = type.type_for(slot)
+        raise "Not found object #{slot}: in #{type}" unless new_type
+      else
+        raise "Not implemented object #{slot}:#{slot.class}"
+      end
+      #puts "RESOLVE in #{@type.class_name} #{slot}->#{type}"
+      return new_type
+    end
+
     # return the frame type, ie the blocks frame type
     def frame_type
       @callable.frame_type
     end
+
     # return the frame type, ie the blocks arguments type
     def arg_type
       @callable.arguments_type
diff --git a/lib/mom/method_compiler.rb b/lib/mom/method_compiler.rb
new file mode 100644
index 00000000..e8c61b11
--- /dev/null
+++ b/lib/mom/method_compiler.rb
@@ -0,0 +1,85 @@
+module Mom
+
+  # MethodCompiler is used to generate Mom instructions for methods
+  # and to instantiate the methods correctly.
+
+  class MethodCompiler < CallableCompiler
+
+    def initialize( method )
+      super(method)
+    end
+
+    #include block_compilers constants
+    def constants
+      block_compilers.inject(@constants.dup){|all, compiler| all += compiler.constants}
+    end
+
+    def source_name
+      "#{@callable.self_type.name}.#{@callable.name}"
+    end
+
+    def get_method
+      @callable
+    end
+
+    # sometimes the method is used as source (tb reviewed)
+    def source
+      @callable
+    end
+
+    # helper method for builtin mainly
+    # the class_name is a symbol, which is resolved to the instance_type of that class
+    #
+    # return compiler_for_type with the resolved type
+    #
+    def self.compiler_for_class( class_name , method_name , args , frame )
+      raise "create_method #{class_name}.#{class_name.class}" unless class_name.is_a? Symbol
+      clazz = Parfait.object_space.get_class_by_name! class_name
+      compiler_for_type( clazz.instance_type , method_name , args , frame)
+    end
+
+    def add_method_to( target )
+      target.add_method( @callable )
+    end
+
+    def create_block(arg_type , frame_type)
+      @callable.create_block(arg_type ,frame_type)
+    end
+
+    # create a method for the given type ( Parfait type object)
+    # method_name is a Symbol
+    # args a hash that will be converted to a type
+    # the created method is set as the current and the given type too
+    # return the compiler
+    def self.compiler_for_type( type , method_name , args , frame)
+      raise "create_method #{type.inspect} is not a Type" unless type.is_a? Parfait::Type
+      raise "Args must be Type #{args}" unless args.is_a?(Parfait::Type)
+      raise "create_method #{method_name}.#{method_name.class}" unless method_name.is_a? Symbol
+      method = type.create_method( method_name , args , frame)
+      self.new(method)
+    end
+
+    # determine how given name need to be accsessed.
+    # For methods the options are args or frame
+    def slot_type_for(name)
+      if @callable.arguments_type.variable_index(name)
+        type = :arguments
+      else
+        type = :frame
+      end
+      [type , name]
+    end
+
+    def add_block_compiler(compiler)
+      @block_compilers << compiler
+    end
+
+    # return true or false if the given name is in scope (arg/local)
+    def in_scope?(name)
+      ret = true if @callable.arguments_type.variable_index(name)
+      ret = @callable.frame_type.variable_index(name) unless ret
+      ret
+    end
+
+  end
+end
diff --git a/lib/mom/mom_collection.rb b/lib/mom/mom_collection.rb
new file mode 100644
index 00000000..06948d1e
--- /dev/null
+++ b/lib/mom/mom_collection.rb
@@ -0,0 +1,86 @@
+module Mom
+  # The Compiler/Collection for the Mom level is a collection of Mom level Method
+  # compilers These will transform to Risc MethodCompilers on the way down.
+  #
+  # As RubyCompiler pools source at the vool level, when several classes are compiled
+  # from vool to mom, several MomCompilers get instantiated. They must be merged before
+  # proceeding with translate. Thus we have a append method.
+  #
+  class MomCollection
+    attr_reader :method_compilers
+
+    # Initialize with an array of risc MethodCompilers
+    def initialize(compilers = [])
+      @method_compilers = compilers
+    end
+
+    # lazily instantiate the compilers for boot functions
+    # (in the hope of only booting the functions once)
+    def boot_compilers
+      @boot_compilers ||= Risc::Builtin.boot_functions
+    end
+
+    # Return all compilers, namely the MethodCompilers passed in, plus the
+    # boot_function's compilers (boot_compilers)
+    def compilers
+      @method_compilers #+ boot_compilers
+    end
+
+    # collects constants from all compilers into one array
+    def constants
+      compilers.inject([]){|sum ,comp| sum + comp.constants }
+    end
+
+    # Append another MomCompilers method_compilers to this one.
+    def append(mom_compiler)
+      @method_compilers += mom_compiler.method_compilers
+      self
+    end
+
+    # Translate code to whatever cpu is specified.
+    # Currently only :arm and :interpret
+    #
+    # Translating means translating the initial jump
+    # and then translating all methods
+    def translate( platform_sym )
+      platform_sym = platform_sym.to_s.capitalize
+      platform = Risc::Platform.for(platform_sym)
+      assemblers = translate_methods( platform.translator )
+      Risc::Linker.new(platform , assemblers , constants)
+    end
+
+    # go through all methods and translate them to cpu, given the translator
+    def translate_methods(translator)
+      compilers.collect do |compiler|
+        #log.debug "Translate method #{compiler.method.name}"
+        translate_method(compiler , translator)
+      end.flatten
+    end
+
+    # translate one method, which means the method itself and all blocks inside it
+    # returns an array of assemblers
+    def translate_method( method_compiler , translator)
+      all = []
+      all << translate_cpu( method_compiler , translator )
+      method_compiler.block_compilers.each do |block_compiler|
+        all << translate_cpu(block_compiler , translator)
+      end
+      all
+    end
+
+    # compile the callable (method or block) to cpu
+    # return an Assembler that will then translate to binary
+    def translate_cpu(compiler , translator)
+      risc = compiler.risc_instructions
+      cpu_instructions = risc.to_cpu(translator)
+      nekst = risc.next
+      while(nekst)
+        cpu = nekst.to_cpu(translator) # returning nil means no replace
+        cpu_instructions << cpu if cpu
+        nekst = nekst.next
+      end
+      Risc::Assembler.new(compiler.callable , cpu_instructions )
+    end
+
+  end
+end
diff --git a/lib/parfait/block.rb b/lib/parfait/block.rb
index dfcd8b7c..438246a1 100644
--- a/lib/parfait/block.rb
+++ b/lib/parfait/block.rb
@@ -3,10 +3,10 @@ module Parfait
   # A Block is a callable object, much like a CallableMethod.
   # Surprisingly similar in fact, as the block is really only missing the name.
   #
-  # The difference lies mostly in the way they are compiled
+  # The difference lies mostly in the way they are compiled (scope and return)
   #
   # Also both have a list of blocks defined in their scope. But this is
-  # notimplemented for blocks yet
+  # not implemented for blocks yet
   #
   class Block < Callable
 
diff --git a/lib/parfait/type.rb b/lib/parfait/type.rb
index b659c734..7f190a25 100644
--- a/lib/parfait/type.rb
+++ b/lib/parfait/type.rb
@@ -1,14 +1,15 @@
 module Parfait
 
-# An Object is really a hash like structure. It is dynamic and
+# An Object is conceptually a hash like structure. It is dynamic and
 # you want to store values by name (instance variable names).
 #
-# One could (like mri), store the names in each object, but that is wasteful in both time and space.
-# Instead we store only the values, and access them by index.
+# One could (like mri), store the names in each object, but that is wasteful in both
+# time and space.
+# Instead we store only the values, and access them by index (bit like c++).
 # The Type allows the mapping of names to index.
 
-# The Type of an object describes the memory layout of the object. In a c analogy, it is the
-# information defined in a struct.
+# The Type of an object describes the memory layout of the object. In a c analogy,
+# it is the information defined in a struct.
 # The Type is a list of the names of instance variables, and their value types (int etc).
 #
 # Every object has a Type to describe it, so it's *first* instance variable is **always**
@@ -21,14 +22,13 @@ module Parfait
 # But Objects must also be able to carry methods themselves (ruby calls singleton_methods)
 # and those too are stored in the Type (both type and class include behaviour)
 
-# The object is an List of values of length n
-
-# The Type is a list of n names and n types that describe the values stored in an actual object.
-
+# The object is an "List" (memory location) of values of length n
+# The Type is a list of n names and n types that describe the values stored in an
+# actual object.
 # Together they turn the object into a hash like structure
 
-# For types to be a useful concept, they have to be unique and immutable. Any "change", like adding
-# a name/type pair, will result in a new instance.
+# For types to be a useful concept, they have to be unique and immutable. Any "change",
+# like adding a name/type pair, will result in a new type instance.
 
 # The Type class carries a hash of types of the systems, which is used to ensure that
 # there is only one instance of every type. Hash and equality are defined on type
diff --git a/lib/parfait/vool_method.rb b/lib/parfait/vool_method.rb
index 8059b6fa..788bfa17 100644
--- a/lib/parfait/vool_method.rb
+++ b/lib/parfait/vool_method.rb
@@ -5,7 +5,7 @@ module Parfait
   # Type objects are already created for args and locals, but the main attribute
   # is the source, which is a Vool::Statement
   #
-  # Classes store VoolMethods, while Types store CallableMethod
+  # Classes store VoolMethods, while Types store Risc::CallableMethod
   # A Type referes to a Class , but a Class (interface) is implemented by many types
   # as it changes during the course of it's life. Types do not change. Objects have
   # type, and so only indirectly a class.
diff --git a/lib/risc/builder.rb b/lib/risc/builder.rb
index aae83391..f75fb9fc 100644
--- a/lib/risc/builder.rb
+++ b/lib/risc/builder.rb
@@ -4,6 +4,12 @@ module Risc
   #
   # The code is added to the method_compiler.
   #
+  # Basically this allows to many Risc instructions with extremely readable code.
+  # example:
+  #  space << Parfait.object_space # load constant
+  #  message[:receiver] << space  #make current message's (r0) receiver the space
+  # See http://ruby-x.org/rubyx/builder.html for details
+  # 
   class Builder
 
     attr_reader :built , :compiler
diff --git a/lib/risc/method_compiler.rb b/lib/risc/method_compiler.rb
index 4a986759..3037700f 100644
--- a/lib/risc/method_compiler.rb
+++ b/lib/risc/method_compiler.rb
@@ -1,8 +1,7 @@
 module Risc
 
-  # MethodCompiler (old name) is used to generate risc instructions for methods
-  # and to instantiate the methods correctly. Most of the init is typed layer stuff,
-  # but there is some logic too.
+  # MethodCompiler is used to generate risc instructions for methods
+  # and to instantiate the methods correctly.
 
   class MethodCompiler < CallableCompiler
 
diff --git a/lib/vool/class_method_statement.rb b/lib/vool/class_method_statement.rb
index 916d6989..076dacd4 100644
--- a/lib/vool/class_method_statement.rb
+++ b/lib/vool/class_method_statement.rb
@@ -11,6 +11,7 @@ module Vool
       raise "not meta" unless clazz.class == Parfait::MetaClass
       raise( "no class in #{self}") unless clazz
       method = clazz.add_method_for(name , make_arg_type , make_frame , body )
+#VoolMethod
       compiler = method.compiler_for(clazz.instance_type)
       each {|node| raise "Blocks not implemented" if node.is_a?(BlockStatement)}
       compiler
diff --git a/lib/vool/class_statement.rb b/lib/vool/class_statement.rb
index 2b768840..254c2fdc 100644
--- a/lib/vool/class_statement.rb
+++ b/lib/vool/class_statement.rb
@@ -29,7 +29,7 @@ module Vool
           raise "Only methods for now #{node.class}:#{node}"
         end
       end
-      Mom::MomCompiler.new(method_compilers)
+      Mom::MomCollection.new(method_compilers)
     end
 
     def each(&block)
diff --git a/test/mom/test_block_compiler.rb b/test/mom/test_block_compiler.rb
new file mode 100644
index 00000000..579b03d9
--- /dev/null
+++ b/test/mom/test_block_compiler.rb
@@ -0,0 +1,85 @@
+require_relative "../helper"
+
+module Mom
+  class TestBlockCompiler < MiniTest::Test
+    include MomCompile
+
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+      @ins = compile_first_block( "local = 5")
+    end
+
+    def test_block_compiles
+      assert_equal Mom::SlotLoad , @ins.class , @ins
+    end
+    def test_slot_is_set
+      assert @ins.left
+    end
+    def test_slot_starts_at_message
+      assert_equal :message , @ins.left.known_object
+    end
+    def test_slots_left
+      assert_equal [:frame , :local] , @ins.left.slots
+    end
+    def test_slot_assigns_something
+      assert @ins.right
+    end
+    def test_slot_assigns_int
+      assert_equal Mom::IntegerConstant ,  @ins.right.known_object.class
+    end
+  end
+
+  class TestAssignMomInstanceToLocal < MiniTest::Test
+    include MomCompile
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+      @ins = compile_first_block( "local = @a" , "@a = 5") #second arg in method scope
+    end
+    def test_class_compiles
+      assert_equal Mom::SlotLoad , @ins.class , @ins
+    end
+    def test_slots_left
+      assert_equal [:frame, :local] , @ins.left.slots
+    end
+    def test_slots_right
+      assert_equal [:receiver, :a] , @ins.right.slots
+    end
+  end
+
+  class TestAssignToArg < MiniTest::Test
+    include MomCompile
+
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+      @ins = compile_first_block( "arg = 5")
+    end
+
+    def test_class_compiles
+      assert_equal Mom::SlotLoad , @ins.class , @ins
+    end
+    def test_slot_is_set
+      assert @ins.left
+    end
+    def test_slots_left
+      assert_equal [:caller,:caller, :arguments, :arg] , @ins.left.slots
+    end
+  end
+
+  class TestAssignMomToInstance < MiniTest::Test
+    include MomCompile
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+    end
+    def test_assigns_const
+      @ins = compile_first_block( "@a = 5")
+      assert_equal Mom::SlotLoad , @ins.class , @ins
+      assert_equal Mom::IntegerConstant , @ins.right.known_object.class , @ins
+    end
+    def test_assigns_move
+      @ins = compile_first_block( "@a = arg")
+      assert_equal Mom::SlotLoad , @ins.class , @ins
+      assert_equal Mom::SlotDefinition , @ins.right.class , @ins
+    end
+  end
+
+end
diff --git a/test/mom/test_method_compiler.rb b/test/mom/test_method_compiler.rb
new file mode 100644
index 00000000..f229c26c
--- /dev/null
+++ b/test/mom/test_method_compiler.rb
@@ -0,0 +1,40 @@
+require_relative "helper"
+
+module Mom
+  class TestMethodCompiler < MiniTest::Test
+    include MomCompile
+
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+      @comp = compile_mom( "class Test ; def main(); return 'Hi'; end; end;")
+    end
+
+    def test_class
+      assert_equal MomCompiler , @comp.class
+    end
+    def test_compilers
+      assert_equal 23 , @comp.compilers.length
+    end
+    def test_boot_compilers
+      assert_equal 22 , @comp.boot_compilers.length
+    end
+    def test_compilers_bare
+      assert_equal 22 , MomCompiler.new.compilers.length
+    end
+    def test_returns_constants
+      assert_equal Array , @comp.constants.class
+    end
+    def test_has_constant
+      assert_equal  "Hi" , @comp.constants[1].to_string
+    end
+    def test_has_translate
+      assert @comp.translate(:interpreter)
+    end
+    def test_append_class
+      assert_equal MomCompiler,  (@comp.append @comp).class
+    end
+    def test_append_length
+      assert_equal 2 ,  @comp.append(@comp).method_compilers.length
+    end
+  end
+end
diff --git a/test/mom/test_mom_collection.rb b/test/mom/test_mom_collection.rb
new file mode 100644
index 00000000..913c466c
--- /dev/null
+++ b/test/mom/test_mom_collection.rb
@@ -0,0 +1,40 @@
+require_relative "helper"
+
+module Mom
+  class TestMomCollection < MiniTest::Test
+    include MomCompile
+
+    def setup
+      Parfait.boot!(Parfait.default_test_options)
+      @comp = compile_mom( "class Test ; def main(); return 'Hi'; end; end;")
+    end
+
+    def test_class
+      assert_equal MomCompiler , @comp.class
+    end
+    def test_compilers
+      assert_equal 23 , @comp.compilers.length
+    end
+    def test_boot_compilers
+      assert_equal 22 , @comp.boot_compilers.length
+    end
+    def test_compilers_bare
+      assert_equal 22 , MomCompiler.new.compilers.length
+    end
+    def test_returns_constants
+      assert_equal Array , @comp.constants.class
+    end
+    def test_has_constant
+      assert_equal  "Hi" , @comp.constants[1].to_string
+    end
+    def test_has_translate
+      assert @comp.translate(:interpreter)
+    end
+    def test_append_class
+      assert_equal MomCompiler,  (@comp.append @comp).class
+    end
+    def test_append_length
+      assert_equal 2 ,  @comp.append(@comp).method_compilers.length
+    end
+  end
+end
diff --git a/test/support/compiling.rb b/test/support/compiling.rb
index 171724f6..7cc17dfe 100644
--- a/test/support/compiling.rb
+++ b/test/support/compiling.rb
@@ -17,6 +17,26 @@ module ScopeHelper
     in_Test("def main(arg) ; #{statements}; end")
   end
 end
+module VoolCompile
+  include ScopeHelper
+
+  def compile_method(input)
+    statements = RubyX::RubyXCompiler.new(RubyX.default_test_options).ruby_to_mom(input)
+    assert statements.is_a?(Mom::MomCollection)
+    ret = statements.to_mom(nil)
+    assert_equal Parfait::Class , statements.clazz.class , statements
+    @method = statements.clazz.get_method(:main)
+    assert_equal Parfait::VoolMethod , @method.class
+    ret
+  end
+  def compile_first_method( input )
+    ret = compile_method( as_test_main( input ))
+    assert_equal Mom::MomCompiler , ret.class
+    compiler = ret.method_compilers.find{|c| c.get_method.name == :main and c.get_method.self_type.object_class.name == :Test}
+    assert_equal Risc::MethodCompiler , compiler.class
+    @method.source.to_mom( compiler )
+  end
+end
 
 module MomCompile
   include ScopeHelper
@@ -78,27 +98,3 @@ module MomCompile
   end
 
 end
-
-
-
-
-class Ignored
-  def == other
-    return false unless other.class == self.class
-    Sof::Util.attributes(self).each do |a|
-      begin
-        left = send(a)
-      rescue NoMethodError
-        next  # not using instance variables that are not defined as attr_readers for equality
-      end
-      begin
-        right = other.send(a)
-      rescue NoMethodError
-        return false
-      end
-      return false unless left.class == right.class
-      return false unless left == right
-    end
-    return true
-  end
-end
diff --git a/test/vool/test_class_statement.rb b/test/vool/test_class_statement.rb
new file mode 100644
index 00000000..7d619daa
--- /dev/null
+++ b/test/vool/test_class_statement.rb
@@ -0,0 +1,29 @@
+
+require_relative "helper"
+
+module Vool
+  class TestClassStatement < MiniTest::Test
+    include VoolCompile
+
+    def setup
+      @ins = compile_first_method( "if(@a) ; @a = 5 ; else; @a = 6 ; end")
+    end
+
+    def test_condition_compiles_to_check
+      assert_equal TruthCheck , @ins.class , @ins
+    end
+    def test_condition_is_slot
+      assert_equal SlotDefinition , @ins.condition.class , @ins
+    end
+    def test_label_after_check
+      assert_equal Label , @ins.next.class , @ins
+    end
+    def test_label_last
+      assert_equal Label , @ins.last.class , @ins
+    end
+    def test_array
+      check_array [TruthCheck, Label, SlotLoad, Jump, Label, SlotLoad ,
+                   Label] , @ins
+    end
+  end
+end