From 7a3fdfea675975d1eab6035353fa5ea7490d1e17 Mon Sep 17 00:00:00 2001
From: Thomas Walpole <twalpole@gmail.com>
Date: Thu, 20 Sep 2018 14:05:41 -0700
Subject: [PATCH] support querying HTML5 attributes

---
 lib/xpath/renderer.rb | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/xpath/renderer.rb b/lib/xpath/renderer.rb
index b8263da..dc10e35 100644
--- a/lib/xpath/renderer.rb
+++ b/lib/xpath/renderer.rb
@@ -59,7 +59,11 @@ def where(on, condition)
     end
 
     def attribute(current, name)
-      "#{current}/@#{name}"
+      if valid_xml_name?(name)
+        "#{current}/@#{name}"
+      else
+        "#{current}/attribute::*[local-name(.) = #{string_literal(name)}]"
+      end
     end
 
     def binary_operator(name, left, right)
@@ -112,5 +116,9 @@ def with_element_conditions(expression, element_names)
         "#{expression}*"
       end
     end
+
+    def valid_xml_name?(name)
+      name =~ /^[a-zA-Z_:][a-zA-Z0-9_:\.\-]*$/
+    end
   end
 end