adding initial MetaWhere support

lib/cancan/model_adapters/abstract_adapter.rb

@@ -26,6 +26,17 @@ module CanCan
         raise NotImplemented, "This model adapter does not support matching on a conditions hash."
       end
 
+      # Used to determine if this model adapter will override the matching behavior for a specific condition.
+      # If this returns true then matches_condition? will be called. See Rule#matches_conditions_hash
+      def self.override_condition_matching?(subject, name, value)
+        false
+      end
+
+      # Override if override_condition_matching? returns true
+      def self.matches_condition?(subject, name, value)
+        raise NotImplemented, "This model adapter does not support matching on a specific condition."
+      end
+
       def initialize(model_class, rules)
         @model_class = model_class
         @rules = rules

lib/cancan/model_adapters/active_record_adapter.rb

@@ -5,6 +5,16 @@ module CanCan
         model_class <= ActiveRecord::Base
       end
 
+      def self.override_condition_matching?(subject, name, value)
+        name.kind_of?(MetaWhere::Column) if defined? MetaWhere
+      end
+
+      def self.matches_condition?(subject, name, value)
+        case name.method
+        when "lt" then subject.send(name.column) < value
+        end
+      end
+
       # Returns conditions intended to be used inside a database query. Normally you will not call this
       # method directly, but instead go through ModelAdditions#accessible_by.
       #

lib/cancan/rule.rb

@@ -100,17 +100,21 @@ module CanCan
           model_adapter(subject).matches_conditions_hash? subject, conditions
         else
           conditions.all? do |name, value|
-            attribute = subject.send(name)
-            if value.kind_of?(Hash)
-              if attribute.kind_of? Array
-                attribute.any? { |element| matches_conditions_hash? element, value }
-              else
-                matches_conditions_hash? attribute, value
-              end
-            elsif value.kind_of?(Array) || value.kind_of?(Range)
-              value.include? attribute
+            if model_adapter(subject).override_condition_matching? subject, name, value
+              model_adapter(subject).matches_condition? subject, name, value
             else
-              attribute == value
+              attribute = subject.send(name)
+              if value.kind_of?(Hash)
+                if attribute.kind_of? Array
+                  attribute.any? { |element| matches_conditions_hash? element, value }
+                else
+                  matches_conditions_hash? attribute, value
+                end
+              elsif value.kind_of?(Array) || value.kind_of?(Range)
+                value.include? attribute
+              else
+                attribute == value
+              end
             end
           end
         end