From 132aa6654f6cf98015d2fd6bf9c4f215e75eec0b Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Wed, 13 Jul 2016 15:07:08 +0100
Subject: [PATCH] add empty_featureset (returning feature_ptr()) implementation

---
 include/mapnik/featureset.hpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/include/mapnik/featureset.hpp b/include/mapnik/featureset.hpp
index c6829d1eb..6886d8755 100644
--- a/include/mapnik/featureset.hpp
+++ b/include/mapnik/featureset.hpp
@@ -41,8 +41,23 @@ struct MAPNIK_DECL Featureset : private util::noncopyable
     virtual ~Featureset() {}
 };
 
+
+struct MAPNIK_DECL empty_featureset final : Featureset
+{
+    feature_ptr next()
+    {
+        return feature_ptr();
+    }
+    ~empty_featureset() {}
+};
+
 using featureset_ptr = std::shared_ptr<Featureset>;
 
+inline featureset_ptr make_empty_featureset()
+{
+    return std::make_shared<empty_featureset>();
+}
+
 }
 
 #endif // MAPNIK_FEATURESET_HPP