[core] Add support for data-driven styling

1 files changed, 17 insertions, 0 deletions

diff --git a/include/mbgl/util/feature.hpp b/include/mbgl/util/feature.hpp
index b72aa15ddd..4eeceda944 100644
--- a/include/mbgl/util/feature.hpp
+++ b/include/mbgl/util/feature.hpp
@@ -12,4 +12,21 @@ using PropertyMap = mapbox::geometry::property_map;
 using FeatureIdentifier = mapbox::geometry::identifier;
 using Feature = mapbox::geometry::feature<double>;
 
+template <class T>
+optional<T> numericValue(const Value& value) {
+    return value.match(
+        [] (uint64_t t) {
+            return optional<T>(t);
+        },
+        [] (int64_t t) {
+            return optional<T>(t);
+        },
+        [] (double t) {
+            return optional<T>(t);
+        },
+        [] (auto) {
+            return optional<T>();
+        });
+}
+
 } // namespace mbgl