Better use of std::variant (#2714)

Signed-off-by: Maksim Derbasov <ntfs.hard@gmail.com>

Author: ntfshard

examples/worlds/ackermann_steering.sdf

@@ -221,7 +221,7 @@
       </link>
 
       <link name='front_right_wheel'>
-        <pose>0.554282 -0.625029 -0.025 -1.5707 0 0</pose>
+        <pose>0.554283 -0.625029 -0.025 -1.5707 0 0</pose>
         <inertial>
           <mass>2</mass>
           <inertia>

src/SystemLoader.cc

@@ -75,14 +75,14 @@ class gz::sim::SystemLoaderPrivate
              << "]. Using [" << filename << "] instead." << std::endl;
     }
 
-    std::list<std::string> paths = this->PluginPaths();
+    const std::list<std::string> paths = this->PluginPaths();
     common::SystemPaths systemPaths;
     for (const auto &p : paths)
     {
       systemPaths.AddPluginPaths(p);
     }
 
-    auto pathToLib = systemPaths.FindSharedLibrary(filename);
+    const auto pathToLib = systemPaths.FindSharedLibrary(filename);
     if (pathToLib.empty())
     {
       // We assume gz::sim corresponds to the levels feature
@@ -94,7 +94,7 @@ class gz::sim::SystemLoaderPrivate
       return false;
     }
 
-    auto pluginNames = this->loader.LoadLib(pathToLib, true);
+    const auto pluginNames = this->loader.LoadLib(pathToLib, true);
     if (pluginNames.empty())
     {
       std::stringstream ss;
@@ -107,7 +107,7 @@ class gz::sim::SystemLoaderPrivate
       return false;
     }
 
-    auto pluginName = *pluginNames.begin();
+    const auto &pluginName = *pluginNames.begin();
     if (pluginName.empty())
     {
       std::stringstream ss;
@@ -200,7 +200,7 @@ class gz::sim::SystemLoaderPrivate
   // Default plugin search path environment variable
   public: std::string pluginPathEnv{"GZ_SIM_SYSTEM_PLUGIN_PATH"};
 
-  /// \brief Plugin loader instace
+  /// \brief Plugin loader instance
   public: gz::plugin::Loader loader;
 
   /// \brief Paths to search for system plugins.
@@ -232,7 +232,7 @@ void SystemLoader::AddSystemPluginPath(const std::string &_path)
 std::optional<SystemPluginPtr> SystemLoader::LoadPlugin(
     const sdf::Plugin &_plugin)
 {
-  if (_plugin.Filename() == "")
+  if (_plugin.Filename().empty())
   {
     gzerr << "Failed to instantiate system plugin: empty argument "
              "[(filename): " << _plugin.Filename() << "] " << std::endl;

src/gui/plugins/apply_force_torque/ApplyForceTorque.cc

@@ -232,7 +232,7 @@ void ApplyForceTorque::LoadConfig(const tinyxml2::XMLElement */*_pluginElem*/)
     this->dataPtr->worldName = worldNames[0].toStdString();
     auto topic = transport::TopicUtils::AsValidTopic(
       "/world/" + this->dataPtr->worldName + "/wrench");
-    if (topic == "")
+    if (topic.empty())
     {
       gzerr << "Unable to create publisher" << std::endl;
       return;
@@ -764,7 +764,7 @@ void ApplyForceTorquePrivate::UpdateVisuals()
     // https://github.com/gazebosim/gz-rendering/pull/882
 
     // Update gizmo visual rotation so that they are always facing the
-    // eye position and alligned with the active vector
+    // eye position and aligned with the active vector
     math::Quaterniond gizmoRot = this->linkWorldPose.Rot() * this->vectorRot;
     math::Vector3d eye = gizmoRot.RotateVectorReverse(
       (this->camera->WorldPosition() - pos).Normalized());

src/gui/plugins/component_inspector/ComponentInspector.cc

@@ -967,7 +967,7 @@ bool ComponentInspector::eventFilter(QObject *_obj, QEvent *_event)
       auto event = reinterpret_cast<gui::events::EntitiesSelected *>(_event);
       if (event && !event->Data().empty())
       {
-        this->SetEntity(*event->Data().begin());
+        this->SetEntity(event->Data().front());
       }
     }
 

src/gui/plugins/component_inspector_editor/ComponentInspectorEditor.cc

@@ -1014,7 +1014,7 @@ bool ComponentInspectorEditor::eventFilter(QObject *_obj, QEvent *_event)
       auto event = reinterpret_cast<gui::events::EntitiesSelected *>(_event);
       if (event && !event->Data().empty())
       {
-        this->SetEntity(*event->Data().begin());
+        this->SetEntity(event->Data().front());
       }
     }
 

src/gui/plugins/joint_position_controller/JointPositionController.cc

@@ -315,7 +315,7 @@ bool JointPositionController::eventFilter(QObject *_obj, QEvent *_event)
       auto event = reinterpret_cast<gui::events::EntitiesSelected *>(_event);
       if (event && !event->Data().empty())
       {
-        this->SetModelEntity(*event->Data().begin());
+        this->SetModelEntity(event->Data().front());
       }
     }
 

src/gui/plugins/mouse_drag/MouseDrag.cc

@@ -680,12 +680,13 @@ void MouseDragPrivate::HandleMouseEvents()
       this->mode = MouseDragMode::NONE;
       return;
     }
-    try
+    if (std::holds_alternative<uint64_t>(
+      visual->Parent()->UserData("gazebo-entity")))
     {
       this->linkId =
         std::get<uint64_t>(visual->Parent()->UserData("gazebo-entity"));
     }
-    catch(std::bad_variant_access &e)
+    else
     {
       this->mode = MouseDragMode::NONE;
       return;

src/gui/plugins/playback_scrubber/PlaybackScrubber.cc

@@ -145,7 +145,7 @@ void PlaybackScrubber::Update(const UpdateInfo &_info,
   }
 
   // Populate the world name
-  if (this->dataPtr->worldName == "")
+  if (this->dataPtr->worldName.empty())
   {
     // TODO(anyone) Only one world is supported for now
     auto worldNames = gz::gui::worldNames();

src/gui/plugins/plot_3d/Plot3D.cc

@@ -270,7 +270,7 @@ bool Plot3D::eventFilter(QObject *_obj, QEvent *_event)
       auto event = reinterpret_cast<gui::events::EntitiesSelected *>(_event);
       if (event && !event->Data().empty())
       {
-        this->SetTargetEntity(*event->Data().begin());
+        this->SetTargetEntity(event->Data().front());
       }
     }
 

src/gui/plugins/resource_spawner/ResourceSpawner.cc

@@ -81,7 +81,7 @@ namespace gz::sim
     public: std::vector<fuel_tools::ServerConfig> servers;
 
     /// \brief Data structure to hold relevant bits for a worker thread that
-    /// fetches the list of recources available for an owner on Fuel.
+    /// fetches the list of resources available for an owner on Fuel.
     struct FetchResourceListWorker
     {
       /// \brief Thread that runs the worker
@@ -441,7 +441,7 @@ bool compareByDownloaded(const Resource &a, const Resource &b)
 /////////////////////////////////////////////////
 void ResourceSpawner::FilterResources(std::vector<Resource> &_resources)
 {
-  if (this->dataPtr->displayData.searchKeyword == "")
+  if (this->dataPtr->displayData.searchKeyword.empty())
     return;
 
   std::string searchKeyword = this->dataPtr->displayData.searchKeyword;