From 6967ed910e6f395bdfe01b7f94eadf04480160a5 Mon Sep 17 00:00:00 2001
From: Christoph Froehlich <christoph.froehlich@ait.ac.at>
Date: Mon, 8 Jan 2024 22:15:23 +0000
Subject: [PATCH] Use enum instead of std::optional

---
 .../hardware_interface/hardware_info.hpp      | 14 ++++++--
 hardware_interface/src/component_parser.cpp   | 36 ++++---------------
 2 files changed, 18 insertions(+), 32 deletions(-)

diff --git a/hardware_interface/include/hardware_interface/hardware_info.hpp b/hardware_interface/include/hardware_interface/hardware_info.hpp
index 97926030c3f..97abc004382 100644
--- a/hardware_interface/include/hardware_interface/hardware_info.hpp
+++ b/hardware_interface/include/hardware_interface/hardware_info.hpp
@@ -15,7 +15,6 @@
 #ifndef HARDWARE_INTERFACE__HARDWARE_INFO_HPP_
 #define HARDWARE_INTERFACE__HARDWARE_INFO_HPP_
 
-#include <optional>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -54,6 +53,14 @@ struct MimicJoint
   double offset = 0.0;
 };
 
+/// @brief This enum is used to store the mimic attribute of a joint
+enum class MimicAttribute
+{
+  NOT_SET,
+  TRUE,
+  FALSE
+};
+
 /**
  * This structure stores information about components defined for a specific hardware
  * in robot's URDF.
@@ -65,8 +72,9 @@ struct ComponentInfo
   /// Type of the component: sensor, joint, or GPIO.
   std::string type;
 
-  ///  If the component has a mimic joint tag, for opt-out
-  std::optional<bool> is_mimic{};
+  ///  Hold the value of the mimic attribute if given, NOT_SET otherwise
+  MimicAttribute is_mimic = MimicAttribute::NOT_SET;
+
   /**
    * Name of the command interfaces that can be set, e.g. "position", "velocity", etc.
    * Used by joints and GPIOs.
diff --git a/hardware_interface/src/component_parser.cpp b/hardware_interface/src/component_parser.cpp
index 34cfa7813bf..308d03b4dd3 100644
--- a/hardware_interface/src/component_parser.cpp
+++ b/hardware_interface/src/component_parser.cpp
@@ -102,29 +102,6 @@ std::string get_attribute_value(
   return element_it->Attribute(attribute_name);
 }
 
-/// Gets value of the attribute on an XMLelement.
-/**
- * If parameter is not found, returns specified default value
- *
- * \param[in] element_it XMLElement iterator to search for the attribute
- * \param[in] attribute_name attribute name to search for and return value
- * \param[in] default_value When the attribute is not found, this value is returned instead
- * \return attribute value
- * \throws std::runtime_error if attribute is not found
- */
-std::string get_attribute_value_or(
-  const tinyxml2::XMLElement * element_it, const char * attribute_name,
-  const std::string default_value)
-{
-  const tinyxml2::XMLAttribute * attr;
-  attr = element_it->FindAttribute(attribute_name);
-  if (!attr)
-  {
-    return default_value;
-  }
-  return element_it->Attribute(attribute_name);
-}
-
 /// Gets value of the attribute on an XMLelement.
 /**
  * If attribute is not found throws an error.
@@ -345,13 +322,14 @@ ComponentInfo parse_component_from_xml(const tinyxml2::XMLElement * component_it
   {
     try
     {
-      component.is_mimic =
-        parse_bool(get_attribute_value(component_it, kMimicAttribute, kJointTag));
+      component.is_mimic = parse_bool(get_attribute_value(component_it, kMimicAttribute, kJointTag))
+                             ? MimicAttribute::TRUE
+                             : MimicAttribute::FALSE;
     }
     catch (const std::runtime_error & e)
     {
       // mimic attribute not set
-      component.is_mimic = {};
+      component.is_mimic = MimicAttribute::NOT_SET;
     }
   }
 
@@ -387,7 +365,7 @@ ComponentInfo parse_component_from_xml(const tinyxml2::XMLElement * component_it
  *  and the interface may be an array of a fixed size of the data type.
  *
  * \param[in] component_it pointer to the iterator where component
- * info should befound
+ * info should be found
  * \throws std::runtime_error if a required component attribute or tag is not found.
  */
 ComponentInfo parse_complex_component_from_xml(const tinyxml2::XMLElement * component_it)
@@ -703,12 +681,12 @@ std::vector<HardwareInfo> parse_control_resources_from_urdf(const std::string &
         {
           throw std::runtime_error("Joint " + joint.name + " not found in URDF");
         }
-        if (!urdf_joint->mimic && joint.is_mimic.value_or(false))
+        if (!urdf_joint->mimic && joint.is_mimic == MimicAttribute::TRUE)
         {
           throw std::runtime_error(
             "Joint '" + std::string(joint.name) + "' has no mimic information in the URDF.");
         }
-        if (urdf_joint->mimic && joint.is_mimic.value_or(true))
+        if (urdf_joint->mimic && joint.is_mimic != MimicAttribute::FALSE)
         {
           if (joint.command_interfaces.size() > 0)
           {