Rework expression conversion

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/CircleLayer.java

@@ -99,7 +99,7 @@ public CircleLayer withFilter(Expression filter) {
   @Nullable
   public Expression getFilter() {
     Expression expression = null;
-    JsonArray array = nativeGetFilter();
+    JsonArray array = (JsonArray) nativeGetFilter();
     if (array != null) {
       expression = Expression.Converter.convert(array);
     }

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/FillExtrusionLayer.java

@@ -99,7 +99,7 @@ public FillExtrusionLayer withFilter(Expression filter) {
   @Nullable
   public Expression getFilter() {
     Expression expression = null;
-    JsonArray array = nativeGetFilter();
+    JsonArray array = (JsonArray) nativeGetFilter();
     if (array != null) {
       expression = Expression.Converter.convert(array);
     }

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/FillLayer.java

@@ -99,7 +99,7 @@ public FillLayer withFilter(Expression filter) {
   @Nullable
   public Expression getFilter() {
     Expression expression = null;
-    JsonArray array = nativeGetFilter();
+    JsonArray array = (JsonArray) nativeGetFilter();
     if (array != null) {
       expression = Expression.Converter.convert(array);
     }

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/HeatmapLayer.java

@@ -99,7 +99,7 @@ public HeatmapLayer withFilter(Expression filter) {
   @Nullable
   public Expression getFilter() {
     Expression expression = null;
-    JsonArray array = nativeGetFilter();
+    JsonArray array = (JsonArray) nativeGetFilter();
     if (array != null) {
       expression = Expression.Converter.convert(array);
     }

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/Layer.java

@@ -3,6 +3,7 @@
 import android.support.annotation.NonNull;
 
 import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
 import com.mapbox.mapboxsdk.style.expressions.Expression;
 
 /**
@@ -72,7 +73,7 @@ public void setMaxZoom(float zoom) {
 
   protected native void nativeSetFilter(Object[] filter);
 
-  protected native JsonArray nativeGetFilter();
+  protected native JsonElement nativeGetFilter();
 
   protected native void nativeSetSourceLayer(String sourceLayer);
 

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/LineLayer.java

@@ -99,7 +99,7 @@ public LineLayer withFilter(Expression filter) {
   @Nullable
   public Expression getFilter() {
     Expression expression = null;
-    JsonArray array = nativeGetFilter();
+    JsonArray array = (JsonArray) nativeGetFilter();
     if (array != null) {
       expression = Expression.Converter.convert(array);
     }

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/SymbolLayer.java

@@ -99,7 +99,7 @@ public SymbolLayer withFilter(Expression filter) {
   @Nullable
   public Expression getFilter() {
     Expression expression = null;
-    JsonArray array = nativeGetFilter();
+    JsonArray array = (JsonArray) nativeGetFilter();
     if (array != null) {
       expression = Expression.Converter.convert(array);
     }

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/layer.java.ejs

@@ -119,7 +119,7 @@ public class <%- camelize(type) %>Layer extends Layer {
   @Nullable
   public Expression getFilter() {
     Expression expression = null;
-    JsonArray array = nativeGetFilter();
+    JsonArray array = (JsonArray) nativeGetFilter();
     if (array != null) {
       expression = Expression.Converter.convert(array);
     }

platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/style/SymbolGeneratorActivity.java

@@ -294,6 +294,13 @@ public void onDataLoaded(@NonNull FeatureCollection featureCollection) {
     Expression textFieldExpressionResult = symbolLayer.getTextField().getExpression();
     Expression textColorExpressionResult = symbolLayer.getTextColor().getExpression();
 
+    // log expressions
+    Timber.e(iconImageExpressionResult.toString());
+    Timber.e(iconSizeExpressionResult.toString());
+    Timber.e(textSizeExpressionResult.toString());
+    Timber.e(textFieldExpressionResult.toString());
+    Timber.e(textColorExpressionResult.toString());
+
     // reset expressions
     symbolLayer.setProperties(
       iconImage(iconImageExpressionResult),

platform/android/config.cmake

@@ -131,7 +131,6 @@ add_library(mbgl-android STATIC
     platform/android/src/conversion/constant.hpp
     platform/android/src/conversion/conversion.hpp
     platform/android/src/style/conversion/function.hpp
-    platform/android/src/style/conversion/gson.hpp
     platform/android/src/style/conversion/property_value.hpp
     platform/android/src/style/conversion/types.hpp
     platform/android/src/style/conversion/types_string_values.hpp
@@ -213,6 +212,8 @@ add_library(mbgl-android STATIC
     platform/android/src/map_renderer_runnable.hpp
 
     # Java core classes
+    platform/android/src/java/lang.cpp
+    platform/android/src/java/lang.hpp
     platform/android/src/java/util.cpp
     platform/android/src/java/util.hpp
 

platform/android/src/gson/json_array.cpp

@@ -6,7 +6,22 @@ namespace mbgl {
 namespace android {
 namespace gson {
 
-std::vector<mapbox::geometry::value> JsonArray::convert(jni::JNIEnv &env, jni::Object<JsonArray> jsonArray) {
+jni::Object<JsonArray> JsonArray::New(jni::JNIEnv& env, const std::vector<mapbox::geometry::value>& values){
+    static auto constructor = JsonArray::javaClass.GetConstructor(env);
+    static auto addMethod = JsonArray::javaClass.GetMethod<void (jni::Object<JsonElement>)>(env, "add");
+
+    auto jsonArray = JsonArray::javaClass.New(env, constructor);
+
+    for (const auto &v : values) {
+        auto jsonElement = JsonElement::New(env, v);
+        jsonArray.Call(env, addMethod, jsonElement);
+        jni::DeleteLocalRef(env, jsonElement);
+    }
+
+    return jsonArray;
+}
+
+std::vector<mapbox::geometry::value> JsonArray::convert(jni::JNIEnv& env, const jni::Object<JsonArray> jsonArray) {
     std::vector<mapbox::geometry::value> values;
 
     if (jsonArray) {
@@ -28,7 +43,7 @@ std::vector<mapbox::geometry::value> JsonArray::convert(jni::JNIEnv &env, jni::O
     return values;
 }
 
-void JsonArray::registerNative(jni::JNIEnv &env) {
+void JsonArray::registerNative(jni::JNIEnv& env) {
     // Lookup the class
     javaClass = *jni::Class<JsonArray>::Find(env).NewGlobalRef(env).release();
 }

platform/android/src/gson/json_array.hpp

@@ -13,6 +13,8 @@ class JsonArray : private mbgl::util::noncopyable {
 public:
     static constexpr auto Name() { return "com/google/gson/JsonArray"; };
 
+    static jni::Object<JsonArray> New(jni::JNIEnv&, const std::vector<mapbox::geometry::value>&);
+
     static std::vector<mapbox::geometry::value> convert(JNIEnv&, jni::Object<JsonArray>);
 
     static jni::Class<JsonArray> javaClass;

platform/android/src/gson/json_element.cpp

@@ -11,6 +11,34 @@ namespace mbgl {
 namespace android {
 namespace gson {
 
+/**
+ * Turn mapbox::geometry::value into Java Gson JsonElement
+ */
+class JsonElementEvaluator {
+public:
+
+    jni::JNIEnv& env;
+
+    jni::Object<JsonElement> operator()(const JsonPrimitive::value value) const {
+        return jni::Cast(env, JsonPrimitive::New(env, value), JsonElement::javaClass);
+    }
+
+    jni::Object<JsonElement> operator()(const std::vector<mapbox::geometry::value> &values) const {
+        return jni::Cast(env, JsonArray::New(env, values), JsonElement::javaClass);
+    }
+
+    jni::Object<JsonElement> operator()(const std::unordered_map<std::string, mapbox::geometry::value> &values) const {
+        return jni::Cast(env, JsonObject::New(env, values), JsonElement::javaClass);
+    }
+
+};
+
+
+jni::Object<JsonElement> JsonElement::New(jni::JNIEnv& env, const mapbox::geometry::value& value) {
+  JsonElementEvaluator evaluator { env } ;
+  return mapbox::geometry::value::visit(value, evaluator);
+}
+
 mapbox::geometry::value JsonElement::convert(jni::JNIEnv &env, jni::Object<JsonElement> jsonElement) {
     mapbox::geometry::value value;
 

platform/android/src/gson/json_element.hpp

@@ -13,6 +13,8 @@ class JsonElement : private mbgl::util::noncopyable {
 public:
     static constexpr auto Name() { return "com/google/gson/JsonElement"; };
 
+    static jni::Object<JsonElement> New(jni::JNIEnv&, const mapbox::geometry::value&);
+
     static mapbox::geometry::value convert(JNIEnv&, jni::Object<JsonElement>);
 
     static bool isJsonObject(JNIEnv&, jni::Object<JsonElement>);

platform/android/src/gson/json_object.cpp

@@ -9,6 +9,23 @@ namespace android {
 namespace gson {
 
 
+jni::Object<JsonObject> JsonObject::New(jni::JNIEnv& env, const std::unordered_map<std::string, mapbox::geometry::value>& values) {
+    static auto constructor = JsonObject::javaClass.GetConstructor(env);
+    static auto addMethod = JsonObject::javaClass.GetMethod<void (jni::String, jni::Object<JsonElement>)>(env, "add");
+
+    jni::Object<JsonObject> jsonObject = JsonObject::javaClass.New(env, constructor);
+
+    for (auto &item : values) {
+        jni::Object<JsonElement> jsonElement = JsonElement::New(env, item.second);
+        jni::String key = jni::Make<jni::String>(env, item.first);
+        jsonObject.Call(env, addMethod, key, jsonElement);
+        jni::DeleteLocalRef(env, jsonElement);
+        jni::DeleteLocalRef(env, key);
+    }
+
+    return jsonObject;
+}
+
 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>>

platform/android/src/gson/json_object.hpp

@@ -13,6 +13,8 @@ class JsonObject : private mbgl::util::noncopyable {
 public:
     static constexpr auto Name() { return "com/google/gson/JsonObject"; };
 
+    static jni::Object<JsonObject> New(jni::JNIEnv&, const std::unordered_map<std::string, mapbox::geometry::value>&);
+
     static mapbox::geometry::property_map convert(JNIEnv&, jni::Object<JsonObject>);
 
     static jni::Class<JsonObject> javaClass;

platform/android/src/gson/json_primitive.cpp

@@ -1,9 +1,89 @@
 #include "json_primitive.hpp"
+#include "../java/lang.hpp"
 
 namespace mbgl {
 namespace android {
 namespace gson {
 
+/**
+ * Turn mapbox::geometry::value into Java Gson JsonPrimitives
+ */
+class JsonPrimitiveEvaluator {
+public:
+
+    jni::JNIEnv& env;
+
+    /**
+     * Create a null primitive
+     */
+    jni::Object<JsonPrimitive> operator()(const mapbox::geometry::null_value_t) const {
+        return jni::Object<JsonPrimitive>();
+    }
+
+    /**
+     * Create a primitive containing a string value
+     */
+    jni::Object<JsonPrimitive> operator()(const std::string value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::String>(env);
+        auto jvalue = jni::Make<jni::String>(env, value);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, jvalue);
+        jni::DeleteLocalRef(env, jvalue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a number value with type double
+     */
+    jni::Object<JsonPrimitive> operator()(const double value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Number>>(env);
+        auto boxedValue = java::lang::Double::valueOf(env, value);
+        auto number = jni::Cast(env, boxedValue, java::lang::Number::javaClass);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, number);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a number value with type long
+     */
+    jni::Object<JsonPrimitive> operator()(const int64_t value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Number>>(env);
+        auto boxedValue = java::lang::Long::valueOf(env, value);
+        auto number = jni::Cast(env, boxedValue, java::lang::Number::javaClass);
+        auto jsonPrimitive =  JsonPrimitive::javaClass.New(env, constructor, number);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a number value with type long
+     */
+    jni::Object<JsonPrimitive> operator()(const uint64_t value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Number>>(env);
+        auto boxedValue = java::lang::Long::valueOf(env, value);
+        auto number = jni::Cast(env, boxedValue, java::lang::Number::javaClass);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, number);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+
+    /**
+     * Create a primitive containing a boolean value
+     */
+    jni::Object<JsonPrimitive> operator()(const bool value) const {
+        static auto constructor = JsonPrimitive::javaClass.GetConstructor<jni::Object<java::lang::Boolean>>(env);
+        auto boxedValue = java::lang::Boolean::valueOf(env, value);
+        auto jsonPrimitive = JsonPrimitive::javaClass.New(env, constructor, boxedValue);
+        jni::DeleteLocalRef(env, boxedValue);
+        return jsonPrimitive;
+    }
+};
+
+jni::Object<JsonPrimitive> JsonPrimitive::New(jni::JNIEnv &env, const value& value) {
+    JsonPrimitiveEvaluator evaluator { env };
+    return value::visit(value, evaluator);
+}
+
 JsonPrimitive::value JsonPrimitive::convert(jni::JNIEnv &env, jni::Object<JsonPrimitive> jsonPrimitive) {
     value value;
     if (jsonPrimitive) {

platform/android/src/gson/json_primitive.hpp

@@ -15,6 +15,8 @@ class JsonPrimitive : private mbgl::util::noncopyable {
 
     static constexpr auto Name() { return "com/google/gson/JsonPrimitive"; };
 
+    static jni::Object<JsonPrimitive> New(jni::JNIEnv&, const value&);
+
     static value convert(JNIEnv&, jni::Object<JsonPrimitive>);
 
     static bool isBoolean(JNIEnv&, jni::Object<JsonPrimitive>);