adding basic ability module

lib/cancan.rb

@@ -0,0 +1,2 @@
+$:.unshift(File.dirname(__FILE__))
+require 'cancan/ability'

lib/cancan/ability.rb

@@ -0,0 +1,39 @@
+module CanCan
+  module Ability
+    def self.included(base)
+      base.extend ClassMethods
+    end
+    
+    def can?(action, target)
+      self.class.can_history.reverse.each do |can_action, can_target, can_block|
+        if can_action == action && (can_target == :all || can_target == target || target.kind_of?(can_target))
+          if can_block.nil?
+            return true
+          else
+            if can_target == :all
+              if target.class == Class
+                return can_block.call(target, nil)
+              else
+                return can_block.call(target.class, target)
+              end
+            elsif can_target == target
+              return can_block.call(nil)
+            else
+              return can_block.call(target)
+            end
+          end
+        end
+      end
+      false
+    end
+    
+    module ClassMethods
+      attr_reader :can_history
+      
+      def can(action, target, &block)
+        @can_history ||= []
+        @can_history << [action, target, block]
+      end
+    end
+  end
+end