From 1a32cc56304ab0e85c937177a0180f92851d818e Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Mon, 12 May 2014 10:12:09 +0100
Subject: [PATCH 1/2] + add eq/neq operators value_null <--> T

---
 include/mapnik/value_types.hpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/include/mapnik/value_types.hpp b/include/mapnik/value_types.hpp
index 5f4133947..680790607 100644
--- a/include/mapnik/value_types.hpp
+++ b/include/mapnik/value_types.hpp
@@ -53,12 +53,26 @@ struct value_null
         return true;
     }
 
+    template <typename T>
+    bool operator==(T const& other) const
+    {
+        boost::ignore_unused_variable_warning(other);
+        return false;
+    }
+
     bool operator!=(value_null const& other) const
     {
         boost::ignore_unused_variable_warning(other);
         return false;
     }
 
+    template <typename T>
+    bool operator!=(T const& other) const
+    {
+        boost::ignore_unused_variable_warning(other);
+        return true;
+    }
+
     template <typename T>
     value_null operator+ (T const& other) const
     {

From ba35dfe3b040f8e7b62d8e99913e54a6c3b8d581 Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Mon, 12 May 2014 10:14:10 +0100
Subject: [PATCH 2/2] mapnik::value - return 'infinity' if rhs == 0 to avoid
 division by zero

---
 include/mapnik/value.hpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/mapnik/value.hpp b/include/mapnik/value.hpp
index 6229c7b79..e0e8333ef 100644
--- a/include/mapnik/value.hpp
+++ b/include/mapnik/value.hpp
@@ -496,6 +496,7 @@ struct div: public boost::static_visitor<V>
     template <typename T>
     value_type operator() (T lhs, T rhs) const
     {
+        if (rhs == 0) return std::numeric_limits<value_type>::infinity();
         return lhs / rhs;
     }
 
@@ -514,11 +515,13 @@ struct div: public boost::static_visitor<V>
 
     value_type operator() (value_double lhs, value_integer rhs) const
     {
+        if (rhs == 0) return std::numeric_limits<value_type>::infinity();
         return lhs / rhs;
     }
 
     value_type operator() (value_integer lhs, value_double rhs) const
     {
+        if (rhs == 0) return std::numeric_limits<value_type>::infinity();
         return lhs / rhs;
     }
 };