Create abstract interface for Priority to be serialized into json

Signed-off-by: Aaron Chong <[email protected]>

rmf_task/CMakeLists.txt

@@ -23,6 +23,7 @@ include(GNUInstallDirs)
 find_package(rmf_utils REQUIRED)
 find_package(rmf_traffic REQUIRED)
 find_package(rmf_battery REQUIRED)
+find_package(nlohmann_json REQUIRED)
 find_package(Eigen3 REQUIRED)
 find_package(Threads)
 
@@ -41,6 +42,7 @@ add_library(rmf_task SHARED
 target_link_libraries(rmf_task
   PUBLIC
     rmf_battery::rmf_battery
+    nlohmann_json::nlohmann_json
     Threads::Threads
     $<$<CXX_COMPILER_ID:GNU>:stdc++fs>
 )

rmf_task/include/rmf_task/Priority.hpp

@@ -19,13 +19,20 @@
 #define RMF_TASK__PRIORITY_HPP
 
 #include <memory>
+#include <nlohmann/json.hpp>
 
 namespace rmf_task {
 
 //==============================================================================
-// Forward declare abstract interface. The definition will remain as internal detail.
-/// A class to specify the priority for a request
-class Priority;
+/// Abstract interface to specify the priority for a request
+class Priority
+{
+public:
+
+  /// Serialize the priority as a json
+  virtual nlohmann::json serialize() const = 0;
+};
+
 using PriorityPtr = std::shared_ptr<Priority>;
 using ConstPriorityPtr = std::shared_ptr<const Priority>;
 

rmf_task/package.xml

@@ -14,6 +14,7 @@
 
   <depend>rmf_battery</depend>
   <depend>rmf_utils</depend>
+  <depend>nlohmann-json-dev</depend>
 
   <depend>eigen</depend>
 

rmf_task/src/rmf_task/BinaryPriority.cpp

@@ -32,4 +32,13 @@ std::size_t BinaryPriority::value() const
   return _value;
 }
 
+//==============================================================================
+nlohmann::json BinaryPriority::serialize() const
+{
+  nlohmann::json priority;
+  priority["type"] = "binary";
+  priority["value"] = _value;
+  return priority;
+}
+
 }

rmf_task/src/rmf_task/BinaryPriority.hpp

@@ -18,7 +18,9 @@
 #ifndef SRC__RMF_TASK__BINARYPRIORITY_HPP
 #define SRC__RMF_TASK__BINARYPRIORITY_HPP
 
-#include "Priority.hpp"
+#include <nlohmann/json.hpp>
+
+#include <rmf_task/Priority.hpp>
 
 namespace rmf_task {
 
@@ -33,6 +35,9 @@ class BinaryPriority : public Priority
   /// Get the value of this priority object
   std::size_t value() const;
 
+  /// Serialize priority
+  nlohmann::json serialize() const override;
+
 private:
   std::size_t _value;
 };