[android] geojson conversion optimisation

1 files changed, 64 insertions, 0 deletions

diff --git a/platform/android/src/gson/json_object.cpp b/platform/android/src/gson/json_object.cpp
new file mode 100644
index 0000000000..a704dae9dd
--- /dev/null
+++ b/platform/android/src/gson/json_object.cpp
@@ -0,0 +1,64 @@
+#include "json_object.hpp"
+
+#include "json_element.hpp"
+
+#include "../java/util.hpp"
+
+namespace mbgl {
+namespace android {
+namespace gson {
+
+
+template <typename F> // void (jni::String, jni::Object<gson::JsonElement>)
+static void iterateEntrySet(jni::JNIEnv& env, jni::Object<JsonObject> jsonObject, F callback) {
+    // Get Set<Map.Entry<String, JsonElement>>
+    static auto method = JsonObject::javaClass.GetMethod<jni::Object<java::util::Set> ()>(env, "entrySet");
+    auto entrySet = jsonObject.Call(env, method);
+    jni::Array<jni::Object<java::util::Map::Entry>> entryArray = java::util::Set::toArray<java::util::Map::Entry>(env, entrySet);
+
+    size_t size = entryArray.Length(env);
+    for (size_t i = 0; i < size; i++) {
+        auto entry = entryArray.Get(env, i);
+        if (entry) {
+            // Convert
+            auto jKey = java::util::Map::Entry::getKey<jni::ObjectTag>(env, entry);
+            auto jKeyString = jni::String(reinterpret_cast<jni::jstring*>(jKey.Get()));
+            auto jValue = java::util::Map::Entry::getValue<gson::JsonElement>(env, entry);
+
+            // Callback
+            callback(jKeyString, jValue);
+
+            // Cleanup
+            // Skip jKey as it points to the same as jKeyString
+            jni::DeleteLocalRef(env, jKeyString);
+            jni::DeleteLocalRef(env, jValue);
+        }
+        jni::DeleteLocalRef(env, entry);
+    }
+
+    jni::DeleteLocalRef(env, entrySet);
+    jni::DeleteLocalRef(env, entryArray);
+}
+
+mapbox::geometry::property_map JsonObject::convert(jni::JNIEnv &env, jni::Object<JsonObject> jsonObject) {
+    mapbox::geometry::property_map map;
+
+    if (jsonObject) {
+        iterateEntrySet(env, jsonObject, [&map, &env](jni::String jId, jni::Object<gson::JsonElement> jsonElement) {
+            map[jni::Make<std::string>(env, jId)] = JsonElement::convert(env, jsonElement);
+        });
+    }
+
+    return map;
+}
+
+void JsonObject::registerNative(jni::JNIEnv &env) {
+    // Lookup the class
+    javaClass = *jni::Class<JsonObject>::Find(env).NewGlobalRef(env).release();
+}
+
+jni::Class<JsonObject> JsonObject::javaClass;
+
+} // namespace gson
+} // namespace android
+} // namespace mbgl
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