upgrades ast to first class

lib/ast/expression.rb

@@ -0,0 +1,87 @@
+# ast classes
+module Ast
+  class Expression
+    def eval 
+      raise "abstract"
+    end
+    def compare other , attributes
+      return false unless other.class == self.class 
+      attributes.each do |a|
+        left = send(a)
+        right = other.send( a)
+        return false unless left.class == right.class 
+        return false unless left == right
+      end
+      return true
+    end
+  end
+
+  class IntegerExpression < Expression
+    attr_reader :value
+    def initialize val
+      @value = val
+    end
+    def == other
+      compare other , [:value]
+    end
+  end
+
+  class NameExpression < Expression
+    attr_reader  :name
+    def initialize name
+      @name = name
+    end
+    def == other
+      compare other ,  [:name]
+    end
+  end
+
+  class StringExpression < Expression
+    attr_reader  :string
+    def initialize str
+      @string = str
+    end
+    def == other
+      compare other ,  [:string]
+    end
+  end
+
+  class FuncallExpression < Expression
+    attr_reader  :name, :args
+    def initialize name, args
+      @name , @args = name , args
+    end
+    def == other
+      compare other , [:name , :args]
+    end
+  end
+
+  class ConditionalExpression < Expression
+    attr_reader  :cond, :if_true, :if_false
+    def initialize cond, if_true, if_false
+      @cond, @if_true, @if_false = cond, if_true, if_false
+    end
+    def == other
+      compare other , [:cond, :if_true, :if_false]
+    end
+  end
+
+  class AssignmentExpression < Expression
+    attr_reader  :assignee, :assigned
+    def initialize assignee, assigned
+      @assignee, @assigned = assignee, assigned
+    end
+    def == other
+      compare other , [:assignee, :assigned]
+    end
+  end
+  class FunctionExpression < Expression
+    attr_reader  :name, :params, :block
+    def initialize name, params, block
+      @name, @params, @block = name, params, block
+    end
+    def == other
+      compare other , [:name, :params, :block]
+    end
+  end
+end