From 1da3bee032184e1f51480978764b281ae0dfbfd8 Mon Sep 17 00:00:00 2001
From: Dane Springmeyer <dane@dbsgeo.com>
Date: Fri, 31 May 2013 12:24:59 -0700
Subject: [PATCH] implement == and != operators on the value_null struct - no
 functional change, but helpful to consolidate logic for comparisions

---
 include/mapnik/value.hpp       | 24 ------------------------
 include/mapnik/value_types.hpp | 10 ++++++++++
 2 files changed, 10 insertions(+), 24 deletions(-)

diff --git a/include/mapnik/value.hpp b/include/mapnik/value.hpp
index 8ea05b7ff..fc792db81 100644
--- a/include/mapnik/value.hpp
+++ b/include/mapnik/value.hpp
@@ -115,12 +115,6 @@ struct equals
         return  (lhs == rhs) ? true: false;
     }
 
-    bool operator() (value_null, value_null) const
-    {
-        // this changed from false to true - https://github.com/mapnik/mapnik/issues/794
-        return true;
-    }
-
     template <typename T>
     bool operator() (T lhs, T rhs) const
     {
@@ -185,24 +179,6 @@ struct not_equals
         return  (lhs != rhs)? true : false;
     }
 
-    bool operator() (value_null, value_null) const
-    {
-        return false;
-    }
-
-    template <typename T>
-    bool operator() (value_null, const T &) const
-    {
-        // https://github.com/mapnik/mapnik/issues/1642
-        return true;
-    }
-
-    template <typename T>
-    bool operator() (const T &, value_null) const
-    {
-        // https://github.com/mapnik/mapnik/issues/1642
-        return true;
-    }
 };
 
 struct greater_than
diff --git a/include/mapnik/value_types.hpp b/include/mapnik/value_types.hpp
index d80bd19cd..41672eb53 100644
--- a/include/mapnik/value_types.hpp
+++ b/include/mapnik/value_types.hpp
@@ -47,6 +47,16 @@ typedef bool value_bool;
 
 struct value_null
 {
+    bool operator==(value_null const& other) const
+    {
+        return true;
+    }
+
+    bool operator!=(value_null const& other) const
+    {
+        return false;
+    }
+
     template <typename T>
     value_null operator+ (T const& /*other*/) const
     {