create draft of ReferenceModels component

Signed-off-by: Ashton Larkin <[email protected]>

include/ignition/gazebo/components/ReferenceModels.hh

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2021 Open Source Robotics Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+*/
+#ifndef IGNITION_GAZEBO_COMPONENTS_REFERENCEMODELS_HH_
+#define IGNITION_GAZEBO_COMPONENTS_REFERENCEMODELS_HH_
+
+// TODO(adlarkin) add missing #include headers
+
+namespace ignition
+{
+namespace gazebo
+{
+// Inline bracket to help doxygen filtering.
+inline namespace IGNITION_GAZEBO_VERSION_NAMESPACE {
+namespace components
+{
+  /// \brief Data structure that holds information about which models for
+  /// a given link view this link as the model's canonical link
+  struct ReferenceModelsInfo
+  {
+    /// \brief The models which this link serves as a canonical link for
+    std::set<Entity> models;
+
+    // TODO(adlarkin) fill in methods below
+
+    // this should be called when a model is assigned to a canonical link
+    public: bool AddModel(const Entity &_model);
+
+    // this should be called when a model is entity is removed/deleted
+    public: bool RemoveModel(const Entity &_model);
+
+    public: bool operator==(const ReferenceModelsInfo &_info) const;
+
+    public: bool operator!=(const ReferenceModelsInfo &_info) const;
+  };
+}
+
+namespace serializers
+{
+  /// \brief Serializer for ReferenceModelsInfo object
+  class ReferenceModelsInfoSerializer
+  {
+    // TODO(adlarkin) write serialization methods
+  };
+}
+
+namespace components
+{
+  /// \brief A component that gives a mapping between a link and all of the
+  /// models this link serves as a canonical link for. This component should
+  /// only be applied to links.
+  using ReferenceModels =
+    Component<ReferenceModelsInfo, class ReferenceModelsTag,
+      serializers::ReferenceModelsInfoSerializer>;
+  IGN_GAZEBO_REGISTER_COMPONENT("ign_gazebo_components.ReferenceModels",
+      ReferenceModels)
+}
+}
+}
+}
+
+#endif