1 files changed, 48 insertions, 0 deletions
diff --git a/lib/arel/session.rb b/lib/arel/session.rb
new file mode 100644
index 0000000000..921ad0a7ac
--- /dev/null
+++ b/lib/arel/session.rb
@@ -0,0 +1,48 @@
+module Arel
+  class Session
+    class << self
+      attr_accessor :instance
+      alias_method :manufacture, :new
+
+      def start
+        if @started
+          yield
+        else
+          begin
+            @started = true
+            @instance = manufacture
+            metaclass.send :alias_method, :new, :instance
+            yield
+          ensure
+            metaclass.send :alias_method, :new, :manufacture
+            @started = false
+          end
+        end
+      end
+    end
+
+    module CRUD
+      def create(insert)
+        insert.call
+        insert
+      end
+
+      def read(select)
+        (@read ||= Hash.new do |hash, select|
+          hash[select] = select.call
+        end)[select]
+      end
+
+      def update(update)
+        update.call
+        update
+      end
+
+      def delete(delete)
+        delete.call
+        delete
+      end
+    end
+    include CRUD
+  end
+end