[core] Change GeoJSONSource::getURL() to return an optional<std::string>

GeoJSON sources may have inline GeoJSON rather than a URL; returning an optional type ensures that consumers handle this case.

include/mbgl/style/sources/geojson_source.hpp

@@ -2,6 +2,7 @@
 
 #include <mbgl/style/source.hpp>
 #include <mbgl/util/geojson.hpp>
+#include <mbgl/util/optional.hpp>
 
 #include <mapbox/geojson.hpp>
 
@@ -42,7 +43,7 @@ public:
     void setURL(const std::string& url);
     void setGeoJSON(const GeoJSON&);
 
-    std::string getURL();
+    optional<std::string> getURL();
 
     // Private implementation
 

platform/default/mbgl/storage/offline_download.cpp

@@ -205,8 +205,8 @@ void OfflineDownload::activateDownload() {
                 style::GeoJSONSource::Impl* geojsonSource =
                     static_cast<style::GeoJSONSource::Impl*>(source->baseImpl.get());
 
-                if (!geojsonSource->loaded) {
-                    ensureResource(Resource::source(geojsonSource->getURL()));
+                if (geojsonSource->getURL()) {
+                    ensureResource(Resource::source(*geojsonSource->getURL()));
                 }
                 break;
             }

src/mbgl/style/sources/geojson_source.cpp

@@ -18,7 +18,7 @@ void GeoJSONSource::setGeoJSON(const mapbox::geojson::geojson& geoJSON) {
     impl->setGeoJSON(geoJSON);
 }
 
-std::string GeoJSONSource::getURL() {
+optional<std::string> GeoJSONSource::getURL() {
     return impl->getURL();
 }
 

src/mbgl/style/sources/geojson_source_impl.cpp

@@ -36,13 +36,12 @@ GeoJSONSource::Impl::Impl(std::string id_, Source& base_, const GeoJSONOptions o
 
 GeoJSONSource::Impl::~Impl() = default;
 
-void GeoJSONSource::Impl::setURL(std::string url) {
-    urlOrGeoJSON = std::move(url);
+void GeoJSONSource::Impl::setURL(std::string url_) {
+    url = std::move(url_);
 }
 
-std::string GeoJSONSource::Impl::getURL() {
-    assert(urlOrGeoJSON.is<std::string>());
-    return urlOrGeoJSON.get<std::string>();
+optional<std::string> GeoJSONSource::Impl::getURL() {
+    return url;
 }
 
 void GeoJSONSource::Impl::setGeoJSON(const GeoJSON& geoJSON) {
@@ -54,7 +53,7 @@ void GeoJSONSource::Impl::setGeoJSON(const GeoJSON& geoJSON) {
         vtOptions.extent = util::EXTENT;
         vtOptions.buffer = std::round(scale * options.buffer);
         vtOptions.tolerance = scale * options.tolerance;
-        urlOrGeoJSON = std::make_unique<mapbox::geojsonvt::GeoJSONVT>(geoJSON, vtOptions);
+        geoJSONOrSupercluster = std::make_unique<mapbox::geojsonvt::GeoJSONVT>(geoJSON, vtOptions);
 
     } else {
         mapbox::supercluster::Options clusterOptions;
@@ -63,13 +62,13 @@ void GeoJSONSource::Impl::setGeoJSON(const GeoJSON& geoJSON) {
         clusterOptions.radius = std::round(scale * options.clusterRadius);
 
         const auto& features = geoJSON.get<mapbox::geometry::feature_collection<double>>();
-        urlOrGeoJSON =
+        geoJSONOrSupercluster =
             std::make_unique<mapbox::supercluster::Supercluster>(features, clusterOptions);
     }
 }
 
 void GeoJSONSource::Impl::load(FileSource& fileSource) {
-    if (!urlOrGeoJSON.is<std::string>()) {
+    if (!url) {
         loaded = true;
         return;
     }
@@ -78,8 +77,7 @@ void GeoJSONSource::Impl::load(FileSource& fileSource) {
         return;
     }
 
-    const std::string& url = urlOrGeoJSON.get<std::string>();
-    req = fileSource.request(Resource::source(url), [this](Response res) {
+    req = fileSource.request(Resource::source(*url), [this](Response res) {
         if (res.error) {
             observer->onSourceError(
                 base, std::make_exception_ptr(std::runtime_error(res.error->message)));
@@ -128,13 +126,13 @@ Range<uint8_t> GeoJSONSource::Impl::getZoomRange() {
 std::unique_ptr<Tile> GeoJSONSource::Impl::createTile(const OverscaledTileID& tileID,
                                                       const UpdateParameters& parameters) {
     assert(loaded);
-    if (urlOrGeoJSON.is<GeoJSONVTPointer>()) {
+    if (geoJSONOrSupercluster.is<GeoJSONVTPointer>()) {
         return std::make_unique<GeoJSONTile>(tileID, base.getID(), parameters,
-                                             *urlOrGeoJSON.get<GeoJSONVTPointer>());
+                                             *geoJSONOrSupercluster.get<GeoJSONVTPointer>());
     } else {
-        assert(urlOrGeoJSON.is<SuperclusterPointer>());
+        assert(geoJSONOrSupercluster.is<SuperclusterPointer>());
         return std::make_unique<GeoJSONTile>(tileID, base.getID(), parameters,
-                                             *urlOrGeoJSON.get<SuperclusterPointer>());
+                                             *geoJSONOrSupercluster.get<SuperclusterPointer>());
     }
 }
 

src/mbgl/style/sources/geojson_source_impl.hpp

@@ -16,9 +16,9 @@ public:
     ~Impl() final;
 
     void setURL(std::string);
-    void setGeoJSON(const GeoJSON&);
+    optional<std::string> getURL();
 
-    std::string getURL();
+    void setGeoJSON(const GeoJSON&);
 
     void load(FileSource&) final;
 
@@ -30,10 +30,10 @@ private:
     Range<uint8_t> getZoomRange() final;
     std::unique_ptr<Tile> createTile(const OverscaledTileID&, const UpdateParameters&) final;
 
-    variant<std::string, GeoJSONVTPointer, SuperclusterPointer> urlOrGeoJSON;
-    std::unique_ptr<AsyncRequest> req;
-
     GeoJSONOptions options;
+    optional<std::string> url;
+    std::unique_ptr<AsyncRequest> req;
+    variant<GeoJSONVTPointer, SuperclusterPointer> geoJSONOrSupercluster;
 };
 
 } // namespace style