diff --git a/lib/oga/xpath/evaluator.rb b/lib/oga/xpath/evaluator.rb
index b1ab513..1999ccf 100644
--- a/lib/oga/xpath/evaluator.rb
+++ b/lib/oga/xpath/evaluator.rb
@@ -10,42 +10,87 @@ module Oga
       #
       def initialize(document)
         @document = document
-        @cursor   = @document
       end
 
-      def on_absolute(node)
-        if @cursor.is_a?(XML::Node)
-          @cursor = @cursor.root_node
+      def process(node, cursor)
+        return if node.nil?
+
+        node = node.to_ast
+
+        on_handler = :"on_#{node.type}"
+
+        if respond_to?(on_handler)
+          new_node = send(on_handler, node, cursor)
+        else
+          new_node = handler_missing(node)
         end
 
-        return process_all(node.children)
+        node = new_node if new_node
+
+        return node
       end
 
-      def on_path(node)
+      def process_all(nodes, cursor)
+        return nodes.to_a.map do |node|
+          process(node, cursor)
+        end
+      end
+
+      def evaluate(string)
+        ast    = Parser.new(string).parse
+        cursor = move_cursor(@document)
+
+        return process(ast, cursor)
+      end
+
+      def on_absolute(node, cursor)
+        if @document.is_a?(XML::Node)
+          cursor = move_cursor(@document.root_node)
+        else
+          cursor = move_cursor(@document)
+        end
+
+        return process_all(node.children, cursor)
+      end
+
+      def on_path(node, cursor)
         test, children = *node
 
-        current = process(test)
+        nodes = process(test, cursor)
 
-        if current
-          @cursor = current
-          current = process(children)
+        unless nodes.empty?
+          nodes = process_all(children, nodes)
         end
 
-        return current
+        return nodes
       end
 
-      def on_test(node)
-        nodes    = []
+      def on_test(node, cursor)
         ns, name = *node
+        nodes    = XML::NodeSet.new
 
-        @cursor.children.each do |child|
-          if child.is_a?(XML::Element) and child.name == name and child.namespace == ns
-            nodes << child
+        cursor.each do |xml_node|
+          next unless xml_node.is_a?(XML::Element)
+
+          if xml_node.name == name and xml_node.namespace == ns
+            nodes << xml_node
           end
         end
 
         return nodes
       end
+
+      def move_cursor(location)
+        if location.is_a?(XML::Document)
+          return location.children
+
+        elsif location.is_a?(XML::Node)
+          return XML::NodeSet.new([location])
+
+        else
+          return location
+        end
+      end
     end # Evaluator
   end # XPath
 end # Oga