From b9ed80ecc89ad748e7bbf54eb512b835ee323146 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_hash.hpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/mapnik/value_hash.hpp b/include/mapnik/value_hash.hpp
index e0aec264e..33f50fccb 100644
--- a/include/mapnik/value_hash.hpp
+++ b/include/mapnik/value_hash.hpp
@@ -76,4 +76,17 @@ std::size_t mapnik_hash_value(T const& val)
 
 } // namespace mapnik
 
+// support for std::unordered containers
+namespace std
+{
+template <>
+struct hash<mapnik::value>
+{
+    size_t operator()(const mapnik::value& val) const
+    {
+        return mapnik::mapnik_hash_value(val);
+    }
+};
+
+
 #endif // MAPNIK_VALUE_HASH_HPP