Add algorithm parameter

include/jwt/algorithm.hpp

@@ -151,6 +151,68 @@ struct ES512
 } //END Namespace algo
 
 
+/*!
+ * JWT signing algorithm.
+ */
+enum class algorithm
+{
+  NONE = 0,
+  HS256,
+  HS384,
+  HS512,
+  RS256,
+  RS384,
+  RS512,
+  ES256,
+  ES384,
+  ES512,
+  TERM,
+};
+
+
+/*!
+ */
+string_view alg_to_str(enum algorithm alg) noexcept
+{
+  switch (alg) {
+    case algorithm::HS256: return "HS256";
+    case algorithm::HS384: return "HS384";
+    case algorithm::HS512: return "HS512";
+    case algorithm::RS256: return "RS256";
+    case algorithm::RS384: return "RS384";
+    case algorithm::RS512: return "RS512";
+    case algorithm::ES256: return "ES256";
+    case algorithm::ES384: return "ES384";
+    case algorithm::ES512: return "ES512";
+    case algorithm::TERM:  return "TERM";
+    case algorithm::NONE:  return "NONE";
+    default:               assert (0 && "Unknown Algorithm");
+  };
+
+  assert (0 && "Code not reached");
+}
+
+/*!
+ */
+enum algorithm str_to_alg(const string_view alg) noexcept
+{
+  if (!alg.length()) return algorithm::NONE;
+
+  if (!strcasecmp(alg.data(), "none"))  return algorithm::NONE;
+  if (!strcasecmp(alg.data(), "hs256")) return algorithm::HS256;
+  if (!strcasecmp(alg.data(), "hs384")) return algorithm::HS384;
+  if (!strcasecmp(alg.data(), "hs512")) return algorithm::HS512;
+  if (!strcasecmp(alg.data(), "rs256")) return algorithm::RS256;
+  if (!strcasecmp(alg.data(), "rs384")) return algorithm::RS384;
+  if (!strcasecmp(alg.data(), "rs512")) return algorithm::RS512;
+  if (!strcasecmp(alg.data(), "es256")) return algorithm::ES256;
+  if (!strcasecmp(alg.data(), "es384")) return algorithm::ES384;
+  if (!strcasecmp(alg.data(), "es512")) return algorithm::ES512;
+
+  assert (0 && "Code not reached");
+}
+
+
 /*!
  */
 template <typename Hasher>

include/jwt/impl/jwt.ipp

@@ -225,6 +225,14 @@ void jwt_object::set_parameters(
   set_parameters(std::forward<Rest>(rargs)...);
 }
 
+template <typename... Rest>
+void jwt_object::set_parameters(
+    params::detail::algorithm_param alg, Rest&&... rargs)
+{
+  header_.algo(alg.get());
+  set_parameters(std::forward<Rest>(rargs)...);
+}
+
 template <typename Map, typename... Rest>
 void jwt_object::set_parameters(
     params::detail::headers_param<Map>&& header, Rest&&... rargs)

include/jwt/jwt.hpp

@@ -19,67 +19,6 @@ using json_t = nlohmann::json;
 
 namespace jwt {
 
-/*!
- * JWT signing algorithm.
- */
-enum class algorithm
-{
-  NONE = 0,
-  HS256,
-  HS384,
-  HS512,
-  RS256,
-  RS384,
-  RS512,
-  ES256,
-  ES384,
-  ES512,
-  TERM,
-};
-
-
-/*!
- */
-string_view alg_to_str(enum algorithm alg) noexcept
-{
-  switch (alg) {
-    case algorithm::HS256: return "HS256";
-    case algorithm::HS384: return "HS384";
-    case algorithm::HS512: return "HS512";
-    case algorithm::RS256: return "RS256";
-    case algorithm::RS384: return "RS384";
-    case algorithm::RS512: return "RS512";
-    case algorithm::ES256: return "ES256";
-    case algorithm::ES384: return "ES384";
-    case algorithm::ES512: return "ES512";
-    case algorithm::TERM:  return "TERM";
-    case algorithm::NONE:  return "NONE";
-    default:               assert (0 && "Unknown Algorithm");
-  };
-
-  assert (0 && "Code not reached");
-}
-
-/*!
- */
-enum algorithm str_to_alg(const string_view alg) noexcept
-{
-  if (!alg.length()) return algorithm::NONE;
-
-  if (!strcasecmp(alg.data(), "none"))  return algorithm::NONE;
-  if (!strcasecmp(alg.data(), "hs256")) return algorithm::HS256;
-  if (!strcasecmp(alg.data(), "hs384")) return algorithm::HS384;
-  if (!strcasecmp(alg.data(), "hs512")) return algorithm::HS512;
-  if (!strcasecmp(alg.data(), "rs256")) return algorithm::RS256;
-  if (!strcasecmp(alg.data(), "rs384")) return algorithm::RS384;
-  if (!strcasecmp(alg.data(), "rs512")) return algorithm::RS512;
-  if (!strcasecmp(alg.data(), "es256")) return algorithm::ES256;
-  if (!strcasecmp(alg.data(), "es384")) return algorithm::ES384;
-  if (!strcasecmp(alg.data(), "es512")) return algorithm::ES512;
-
-  assert (0 && "Code not reached");
-}
-
 /*!
  */
 enum class type
@@ -608,6 +547,11 @@ private: // private APIs
   template <typename... Rest>
   void set_parameters(params::detail::secret_param, Rest&&...);
 
+  /**
+   */
+  template <typename... Rest>
+  void set_parameters(params::detail::algorithm_param, Rest&&...);
+
   /**
    */
   template <typename M, typename... Rest>

include/jwt/parameters.hpp

@@ -5,6 +5,7 @@
 #include <utility>
 #include <unordered_map>
 
+#include "jwt/algorithm.hpp"
 #include "jwt/detail/meta.hpp"
 #include "jwt/string_view.hpp"
 
@@ -55,6 +56,31 @@ struct secret_param
   string_view secret_;
 };
 
+/**
+ * Parameter for providing the algorithm to use.
+ * The parameter can accept either the string representation
+ * or the enum class.
+ *
+ * Modeled as ParameterConcept.
+ */
+struct algorithm_param
+{
+  algorithm_param(const string_view alg)
+    : alg_(str_to_alg(alg))
+  {}
+
+  algorithm_param(jwt::algorithm alg)
+    : alg_(alg)
+  {}
+
+  jwt::algorithm get() const noexcept
+  {
+    return alg_;
+  }
+
+  typename jwt::algorithm alg_;
+};
+
 /**
  * Parameter for providing additional headers.
  * Takes a mapping concept representing
@@ -108,11 +134,25 @@ payload(const param_init_list_t& kvs)
 
 /**
  */
-detail::secret_param secret(string_view sv)
+detail::secret_param secret(const string_view sv)
 {
   return { sv };
 }
 
+/**
+ */
+detail::algorithm_param algorithm(const string_view sv)
+{
+  return { sv };
+}
+
+/**
+ */
+detail::algorithm_param algorithm(jwt::algorithm alg)
+{
+  return { alg };
+}
+
 /**
  */
 template <typename MappingConcept,