From 047ec966705138c905658f154c1f97dd099781c4 Mon Sep 17 00:00:00 2001
From: Steve Peters <scpeters@openrobotics.org>
Date: Fri, 15 May 2020 14:39:07 -0700
Subject: [PATCH] Model DOM: add accessor API's for nested models

Signed-off-by: Steve Peters <scpeters@openrobotics.org>
---
 Migration.md         |  4 ++++
 include/sdf/Model.hh | 23 +++++++++++++++++++++++
 src/Model.cc         | 43 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+)

diff --git a/Migration.md b/Migration.md
index a9cc6a395..68d8d3275 100644
--- a/Migration.md
+++ b/Migration.md
@@ -45,6 +45,10 @@ but with improved human-readability..
     + const Frame \*FrameByIndex(const uint64\_t) const
     + const Frame \*FrameByName(const std::string &) const
     + bool FrameNameExists(const std::string &) const
+    + uint64\_t ModelCount() const
+    + const Model \*ModelByIndex(const uint64\_t) const
+    + const Model \*ModelByName(const std::string &) const
+    + bool ModelNameExists(const std::string &) const
     + sdf::SemanticPose SemanticPose() const
 
 1. **sdf/SDFImpl.hh**
diff --git a/include/sdf/Model.hh b/include/sdf/Model.hh
index 018801982..d63899807 100644
--- a/include/sdf/Model.hh
+++ b/include/sdf/Model.hh
@@ -198,6 +198,29 @@ namespace sdf
     /// \return True if there exists an explicit frame with the given name.
     public: bool FrameNameExists(const std::string &_name) const;
 
+    /// \brief Get the number of nested models.
+    /// \return Number of nested models contained in this Model object.
+    public: uint64_t ModelCount() const;
+
+    /// \brief Get a nested model based on an index.
+    /// \param[in] _index Index of the nested model. The index should be in the
+    /// range [0..ModelCount()).
+    /// \return Pointer to the model. Nullptr if the index does not exist.
+    /// \sa uint64_t ModelCount() const
+    public: const Model *ModelByIndex(const uint64_t _index) const;
+
+    /// \brief Get whether a nested model name exists.
+    /// \param[in] _name Name of the nested model to check.
+    /// \return True if there exists a nested model with the given name.
+    public: bool ModelNameExists(const std::string &_name) const;
+
+    /// \brief Get a nested model based on a name.
+    /// \param[in] _name Name of the nested model.
+    /// \return Pointer to the model. Nullptr if a model with the given name
+    ///  does not exist.
+    /// \sa bool ModelNameExists(const std::string &_name) const
+    public: const Model *ModelByName(const std::string &_name) const;
+
     /// \brief Get the pose of the model. This is the pose of the model
     /// as specified in SDF (<model> <pose> ... </pose></model>), and is
     /// typically used to express the position and rotation of a model in a
diff --git a/src/Model.cc b/src/Model.cc
index fe8be53ee..656ba2977 100644
--- a/src/Model.cc
+++ b/src/Model.cc
@@ -67,6 +67,9 @@ class sdf::ModelPrivate
   /// \brief The frames specified in this model.
   public: std::vector<Frame> frames;
 
+  /// \brief The nested models specified in this model.
+  public: std::vector<Model> models;
+
   /// \brief The SDF element pointer used during load.
   public: sdf::ElementPtr sdf;
 
@@ -527,6 +530,46 @@ const Frame *Model::FrameByName(const std::string &_name) const
   return nullptr;
 }
 
+/////////////////////////////////////////////////
+uint64_t Model::ModelCount() const
+{
+  return this->dataPtr->models.size();
+}
+
+/////////////////////////////////////////////////
+const Model *Model::ModelByIndex(const uint64_t _index) const
+{
+  if (_index < this->dataPtr->models.size())
+    return &this->dataPtr->models[_index];
+  return nullptr;
+}
+
+/////////////////////////////////////////////////
+bool Model::ModelNameExists(const std::string &_name) const
+{
+  for (auto const &m : this->dataPtr->models)
+  {
+    if (m.Name() == _name)
+    {
+      return true;
+    }
+  }
+  return false;
+}
+
+/////////////////////////////////////////////////
+const Model *Model::ModelByName(const std::string &_name) const
+{
+  for (auto const &m : this->dataPtr->models)
+  {
+    if (m.Name() == _name)
+    {
+      return &m;
+    }
+  }
+  return nullptr;
+}
+
 /////////////////////////////////////////////////
 const Link *Model::CanonicalLink() const
 {