1 files changed, 30 insertions, 0 deletions
diff --git a/src/mbgl/renderer/style_diff.hpp b/src/mbgl/renderer/style_diff.hpp
new file mode 100644
index 0000000000..dc2ef95c6c
--- /dev/null
+++ b/src/mbgl/renderer/style_diff.hpp
@@ -0,0 +1,30 @@
+#include <mbgl/style/source_impl.hpp>
+#include <mbgl/style/layer_impl.hpp>
+#include <mbgl/util/immutable.hpp>
+#include <mbgl/util/variant.hpp>
+
+#include <unordered_map>
+
+namespace mbgl {
+
+template <class T>
+class StyleDifference {
+public:
+    std::unordered_map<std::string, T> added;
+    std::unordered_map<std::string, T> removed;
+    std::unordered_map<std::string, T> changed;
+};
+
+using ImmutableSource = Immutable<style::Source::Impl>;
+using SourceDifference = StyleDifference<ImmutableSource>;
+
+SourceDifference diffSources(const std::vector<ImmutableSource>&,
+                             const std::vector<ImmutableSource>&);
+
+using ImmutableLayer = Immutable<style::Layer::Impl>;
+using LayerDifference = StyleDifference<ImmutableLayer>;
+
+LayerDifference diffLayers(const std::vector<ImmutableLayer>&,
+                           const std::vector<ImmutableLayer>&);
+
+} // namespace mbgl