From 748cc79d0f1b0f9ff19f35c2fc056b12414b33b7 Mon Sep 17 00:00:00 2001
From: Maxime Coste <frrrwww@gmail.com>
Date: Thu, 24 Oct 2013 22:21:41 +0100
Subject: [PATCH] Add std::hash specialization for std::pair

---
 src/utils.hh | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/utils.hh b/src/utils.hh
index 4ff1839b..0500b203 100644
--- a/src/utils.hh
+++ b/src/utils.hh
@@ -300,4 +300,21 @@ private:
 
 }
 
+// std::pair hashing
+namespace std
+{
+
+template<typename T1, typename T2>
+struct hash<std::pair<T1,T2>>
+{
+    size_t operator()(const std::pair<T1,T2>& val) const
+    {
+        size_t seed = std::hash<T2>()(val.second);
+        return seed ^ (std::hash<T1>()(val.first) + 0x9e3779b9 +
+                       (seed << 6) + (seed >> 2));
+    }
+};
+
+}
+
 #endif // utils_hh_INCLUDED