fixup! common: Add jansson support header

Signed-off-by: Philipp Jungkamp <philipp.jungkamp@rwth-aachen.de>

Author: pjungkamp

common/include/villas/jansson.hpp

@@ -1,3 +1,10 @@
+/* Jansson support header.
+ *
+ * Author: Philipp Jungkamp <philipp.jungkamp@rwth-aachen.de>
+ * SPDX-FileCopyrightText: 2014-2026 Institute for Automation of Complex Power Systems, RWTH Aachen University
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 #pragma once
 
 #include <initializer_list>
@@ -10,9 +17,9 @@
 
 namespace villas {
 
-// smart pointer for ::json_t values.
+// Smart pointer for ::json_t values.
 //
-// this class mirrors the interface of std::shared_ptr using the internal reference count of ::json_t
+// This class mirrors the interface of std::shared_ptr using the internal reference count of ::json_t.
 class JanssonPtr {
 public:
   JanssonPtr() : inner(nullptr) {}
@@ -59,27 +66,27 @@ class JanssonPtr {
   ::json_t *inner;
 };
 
-// type trait helper for applying variadic default promotions
+// Type trait helper for applying variadic default promotions.
 template <typename T> class va_default_promote {
   static auto impl() {
     using U = std::decay_t<T>;
     if constexpr (std::is_enum_v<U>) {
       if constexpr (std::is_convertible_v<U, std::underlying_type_t<U>>) {
-        // unscoped enumerations are converted to their underlying type and then promoted using integer promotions
+        // Unscoped enumerations are converted to their underlying type and then promoted using integer promotions.
         return std::type_identity<
             decltype(+std::declval<std::underlying_type_t<U>>())>();
       } else {
-        // scoped enumeration handling is implementation defined just pass them without promotions
+        // Scoped enumeration handling is implementation defined just pass them without promotions.
         return std::type_identity<U>();
       }
     } else if constexpr (std::is_same_v<float, U>) {
-      // float values are promoted to double
+      // Floating point values are promoted to double.
       return std::type_identity<double>();
     } else if constexpr (std::is_integral_v<U>) {
-      // integral values are promoted using integer promotions
+      // Integral values are promoted using integer promotions.
       return std::type_identity<decltype(+std::declval<U>())>();
     } else {
-      // default case without any promotions
+      // The default case without any promotions.
       return std::type_identity<U>();
     }
   }
@@ -90,7 +97,7 @@ template <typename T> class va_default_promote {
 
 template <typename T> using va_default_promote_t = va_default_promote<T>::type;
 
-// helper type for validating format strings
+// A helper type for validating format strings.
 enum class JanssonFormatArg {
   KEY,
   STRING,
@@ -104,7 +111,7 @@ enum class JanssonFormatArg {
   JSON,
 };
 
-// make a JanssonFormatArg from a type using template specializations
+// Make a JanssonFormatArg for a type.
 template <typename T> consteval JanssonFormatArg makeJanssonFormatArg() {
   if (std::is_same_v<T, char const>)
     return JanssonFormatArg::KEY;
@@ -134,13 +141,13 @@ template <typename T> consteval JanssonFormatArg makeJanssonFormatArg() {
 template <typename T>
 constexpr static JanssonFormatArg janssonFormatArg = makeJanssonFormatArg<T>();
 
-// helper type for validating format strings with nested structures
+// Helper type for validating format strings with nested structures.
 enum class JanssonNestedStructure {
   OBJECT,
   ARRAY,
 };
 
-// compile time validator for json_unpack-style format strings
+// Compile time validator for json_unpack-style format strings.
 template <typename... Args> class JanssonUnpackFormatString {
 public:
   consteval JanssonUnpackFormatString(char const *fmt) : fmt(fmt) {
@@ -295,7 +302,7 @@ void janssonUnpack(::json_t *json,
     throw RuntimeError("Could not unpack json value: {}", err.text);
 }
 
-// compile time validator for json_pack-style format strings
+// Compile time validator for json_pack-style format strings.
 template <typename... Args> class JanssonPackFormatString {
 public:
   consteval JanssonPackFormatString(char const *fmt) : fmt(fmt) {