From 022c2f7255a48140f26d13d64a741cdf441ea8ab Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Thu, 18 Jun 2015 10:10:26 +0200
Subject: [PATCH] add std::hash specialization for mapnik::value

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

diff --git a/include/mapnik/value.hpp b/include/mapnik/value.hpp
index 604dd8669..c4c37b446 100644
--- a/include/mapnik/value.hpp
+++ b/include/mapnik/value.hpp
@@ -990,4 +990,18 @@ inline bool value::is_null() const
 
 } // namespace mapnik
 
+// support for std::unordered_xxx
+namespace std
+{
+template <>
+struct hash<mapnik::value>
+{
+    size_t operator()(mapnik::value const& val) const
+    {
+        return mapnik::mapnik_hash_value(val);
+    }
+};
+
+}
+
 #endif // MAPNIK_VALUE_HPP