add module names and instance variables as parse rules

lib/ast/basic_expressions.rb

@@ -42,6 +42,11 @@ module Ast
     end
   end
 
+  class VariableExpression < NameExpression
+  end
+  class ModuleName < NameExpression
+  end
+
   class StringExpression < Expression
     attr_reader  :string
     def initialize str

lib/parser/basic_types.rb

@@ -25,7 +25,13 @@ module Parser
     rule(:exponent) { (str('e')| str('E')) }
      
     # identifier must start with lower case
-    rule(:name)   { keyword.absent? >> (match['a-z'] >> match['a-zA-Z0-9'].repeat).as(:name)  >> space? }
+    # TODO rule forbit names like if_true, because it starts with a keyword. a little looser please!
+    rule(:name)   { keyword.absent? >> (match['a-z_'] >> match['a-zA-Z0-9_'].repeat).as(:name)  >> space? }
+    # instance variables must have the @
+    rule(:instance_variable) { (match('@') >> name).as(:instance_variable) }
+    # and class/module names must start with capital 
+    # (admittatly the rule matches constants too, but one step at a time)
+    rule(:module_name) { keyword.absent? >> (match['A-Z'] >> match['a-zA-Z0-9_'].repeat).as(:module_name)  >> space? }
     
     rule(:escape)     { str('\\') >> any.as(:esc) }
     rule(:string)     { quote >> (

lib/parser/transform.rb

@@ -9,6 +9,8 @@ module Parser
     
     rule(:integer => simple(:value)) { Ast::IntegerExpression.new(value.to_i) }
     rule(:name   => simple(:name))  { Ast::NameExpression.new(name.to_s) }
+    rule(:instance_variable   => simple(:instance_variable))  { Ast::VariableExpression.new(instance_variable.name) }
+    rule(:module_name   => simple(:module_name))  { Ast::ModuleName.new(module_name.to_s) }
 
     rule(:array_constant => sequence(:array_constant) ) { Ast::ArrayExpression.new(array_constant) } 
     rule(:array_element  => simple(:array_element))    { array_element  }