add json parser

fpga/include/villas/fpga/json_parser.hpp

@@ -0,0 +1,54 @@
+/*  Wrapper for Jannson library to process Json files in OOP.
+ *
+ * Author: Pascal Bauer <pascal.bauer@rwth-aachen.de>
+ *
+ * SPDX-FileCopyrightText: 2023-2024 Pascal Bauer <pascal.bauer@rwth-aachen.de>
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <jansson.h>
+#include <memory>
+#include <spdlog/common.h>
+#include <string>
+
+
+class JsonParser {
+private:
+  inline static auto logger = villas::Log::get("Json Parser");
+
+public:
+  json_t* json;
+
+public:
+  JsonParser(json_t *json) : json(json) {}
+
+  JsonParser(const std::string &configFilePath) {
+    FILE *f = fopen(configFilePath.c_str(), "r");
+    if (!f)
+      throw RuntimeError("Cannot open config file: {}", configFilePath);
+
+    this->json = json_loadf(f, 0, nullptr);
+    if (!json) {
+      logger->error("Cannot parse JSON config");
+      fclose(f);
+      throw RuntimeError("Cannot parse JSON config");
+    }
+
+    fclose(f);
+  }
+
+  ~JsonParser() {
+    json_decref(json);
+  }
+
+  json_t* get(const std::string &key) {
+    json_t* result = json_object_get(this->json, key.c_str());
+    if (result == nullptr) {
+      logger->error("No section {} found in config", key);
+      exit(1);
+    }
+    return result;
+  }
+};