Add Low Fidelity NetworkTables simulation extension (#823)

simulation/halsim_lowfi/src/main/native/include/HALSimLowFi.h

@@ -0,0 +1,58 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2017 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <cinttypes>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <MockData/NotifyListener.h>
+#include <networktables/NetworkTableInstance.h>
+
+class HALSimLowFi {
+ public:
+  std::shared_ptr<nt::NetworkTable> table;
+  void Initialize();
+};
+
+typedef void (*HALCbRegisterIndexedFunc)(int32_t index,
+                                         HAL_NotifyCallback callback,
+                                         void* param, HAL_Bool initialNotify);
+typedef void (*HALCbRegisterSingleFunc)(HAL_NotifyCallback callback,
+                                        void* param, HAL_Bool initialNotify);
+
+void NTProviderBaseCallback(const char* name, void* param,
+                            const struct HAL_Value* value);
+
+class HALSimNTProvider {
+ public:
+  struct NTProviderCallbackInfo {
+    HALSimNTProvider* provider;
+    std::shared_ptr<nt::NetworkTable> table;
+    int channel;
+  };
+
+  void Inject(std::shared_ptr<HALSimLowFi> parent, std::string table);
+  // Initialize is called by inject.
+  virtual void Initialize() = 0;
+  virtual void InitializeDefault(int numChannels,
+                                 HALCbRegisterIndexedFunc registerFunc);
+  virtual void InitializeDefaultSingle(HALCbRegisterSingleFunc registerFunc);
+  virtual void OnCallback(uint32_t channel,
+                          std::shared_ptr<nt::NetworkTable> table) = 0;
+  virtual void OnInitializedChannel(uint32_t channel,
+                                    std::shared_ptr<nt::NetworkTable> table);
+
+  int numChannels;
+  std::string tableName;
+
+  std::shared_ptr<HALSimLowFi> parent;
+  std::shared_ptr<nt::NetworkTable> table;
+  std::vector<NTProviderCallbackInfo> cbInfos;
+};