[core, node] Implement bindings for addLayer

1 files changed, 16 insertions, 0 deletions

diff --git a/src/mbgl/style/rapidjson_conversion.hpp b/src/mbgl/style/rapidjson_conversion.hpp
index 1d9f88efa3..ecf044fb64 100644
--- a/src/mbgl/style/rapidjson_conversion.hpp
+++ b/src/mbgl/style/rapidjson_conversion.hpp
@@ -2,11 +2,16 @@
 
 #include <mbgl/util/rapidjson.hpp>
 #include <mbgl/util/feature.hpp>
+#include <mbgl/style/conversion.hpp>
 
 namespace mbgl {
 namespace style {
 namespace conversion {
 
+inline bool isUndefined(const JSValue& value) {
+    return value.IsNull();
+}
+
 inline bool isArray(const JSValue& value) {
     return value.IsArray();
 }
@@ -30,6 +35,17 @@ inline const JSValue* objectMember(const JSValue& value, const char * name) {
     return &value[name];
 }
 
+template <class Fn>
+optional<Error> eachMember(const JSValue& value, Fn&& fn) {
+    for (auto it = value.MemberBegin(); it != value.MemberEnd(); ++it) {
+        optional<Error> result = fn({it->name.GetString(), it->name.GetStringLength()}, it->value);
+        if (result) {
+            return result;
+        }
+    }
+    return {};
+}
+
 inline optional<bool> toBool(const JSValue& value) {
     if (!value.IsBool()) {
         return {};