Add generic setter for 'source' property

- Add setter for 'source' property
- Test generic setters via setProperty method

include/mbgl/style/layer.hpp

@@ -94,6 +94,7 @@ public:
     std::string getSourceID() const;
     std::string getSourceLayer() const;
     void setSourceLayer(const std::string& sourceLayer);
+    void setSourceID(const std::string& sourceID);
 
     // Filter
     const Filter& getFilter() const;

src/mbgl/style/layer.cpp

@@ -41,16 +41,25 @@ std::string Layer::getSourceLayer() const {
 }
 
 void Layer::setSourceLayer(const std::string& sourceLayer) {
+    if (getSourceLayer() == sourceLayer) return;
     auto impl_ = mutableBaseImpl();
     impl_->sourceLayer = sourceLayer;
     baseImpl = std::move(impl_);
 }
 
+void Layer::setSourceID(const std::string& sourceID) {
+    if (getSourceID() == sourceID) return;
+    auto impl_ = mutableBaseImpl();
+    impl_->source = sourceID;
+    baseImpl = std::move(impl_);
+};
+
 const Filter& Layer::getFilter() const {
     return baseImpl->filter;
 }
 
 void Layer::setFilter(const Filter& filter) {
+    if (getFilter() == filter) return;
     auto impl_ = mutableBaseImpl();
     impl_->filter = filter;
     baseImpl = std::move(impl_);
@@ -79,6 +88,7 @@ float Layer::getMaxZoom() const {
 }
 
 void Layer::setMinZoom(float minZoom) {
+    if (getMinZoom() == minZoom) return;
     auto impl_ = mutableBaseImpl();
     impl_->minZoom = minZoom;
     baseImpl = std::move(impl_);
@@ -86,6 +96,7 @@ void Layer::setMinZoom(float minZoom) {
 }
 
 void Layer::setMaxZoom(float maxZoom) {
+    if (getMaxZoom() == maxZoom) return;
     auto impl_ = mutableBaseImpl();
     impl_->maxZoom = maxZoom;
     baseImpl = std::move(impl_);
@@ -168,7 +179,7 @@ optional<conversion::Error> Layer::setProperty(const std::string& name, const co
         if (auto sourceLayer = convert<std::string>(value, *error)) {
             if (getTypeInfo()->source != LayerTypeInfo::Source::Required) {
                 Log::Warning(mbgl::Event::General,
-                             "source-layer property cannot be applied to"
+                             "'source-layer' property cannot be set to"
                              "the layer %s",
                              baseImpl->id.c_str());
                 return nullopt;
@@ -176,6 +187,18 @@ optional<conversion::Error> Layer::setProperty(const std::string& name, const co
             setSourceLayer(*sourceLayer);
             return nullopt;
         }
+    } else if (name == "source") {
+        if (auto sourceID = convert<std::string>(value, *error)) {
+            if (getTypeInfo()->source != LayerTypeInfo::Source::Required) {
+                Log::Warning(mbgl::Event::General,
+                             "'source' property cannot be set to"
+                             "the layer %s",
+                             baseImpl->id.c_str());
+                return nullopt;
+            }
+            setSourceID(*sourceID);
+            return nullopt;
+        }
     }
     return error;
 }

test/style/conversion/layer.test.cpp

@@ -148,4 +148,20 @@ TEST(StyleConversion, SetGenericProperties) {
     EXPECT_EQ(12.0f, layer->getMinZoom());
     EXPECT_EQ(18.0f, layer->getMaxZoom());
     EXPECT_EQ("landmarks", layer->getSourceLayer());
+
+    const JSValue newComposite("composite_2");
+    layer->setProperty("source", Convertible(&newComposite));
+    EXPECT_EQ("composite_2", layer->getSourceID());
+
+    const JSValue newSourceLayer("poi");
+    layer->setProperty("source-layer", Convertible(&newSourceLayer));
+    EXPECT_EQ("poi", layer->getSourceLayer());
+
+    const JSValue newMinZoom(1.0f);
+    layer->setProperty("minzoom", Convertible(&newMinZoom));
+    EXPECT_EQ(1.0f, layer->getMinZoom());
+
+    const JSValue newMaxZoom(22.0f);
+    layer->setProperty("maxzoom", Convertible(&newMaxZoom));
+    EXPECT_EQ(22.0f, layer->getMaxZoom());
 }

test/style/style_layer.test.cpp

@@ -1,5 +1,7 @@
 #include <mbgl/gl/custom_layer.hpp>
 #include <mbgl/gl/custom_layer_impl.hpp>
+#include <mbgl/style/conversion/filter.hpp>
+#include <mbgl/style/conversion/json.hpp>
 #include <mbgl/style/expression/dsl.hpp>
 #include <mbgl/style/expression/format_expression.hpp>
 #include <mbgl/style/expression/image.hpp>
@@ -28,6 +30,7 @@
 
 using namespace mbgl;
 using namespace mbgl::style;
+using namespace mbgl::style::conversion;
 using namespace expression;
 using namespace expression::dsl;
 using namespace std::literals::string_literals;
@@ -60,6 +63,11 @@ class MockLayoutProperties : public Properties<TextField> {};
 class MockPaintProperties : public Properties<TextColor> {};
 using MockOverrides = FormatSectionOverrides<MockPaintProperties::OverridableProperties>;
 
+mbgl::style::Filter parseFilter(const std::string& expression) {
+    Error error;
+    return *convertJSON<mbgl::style::Filter>(expression, error);
+}
+
 } // namespace
 
 TEST(Layer, BackgroundProperties) {
@@ -221,7 +229,7 @@ TEST(Layer, Observer) {
         EXPECT_EQ(layer.get(), &layer_);
         filterChanged = true;
     };
-    layer->setFilter(Filter());
+    layer->setFilter(parseFilter(R"(["==", "foo", "bar"])"));
     EXPECT_TRUE(filterChanged);
 
     // Notifies observer on visibility change.