container: root: add plugins support

- Implements support for docker-finance C++ plugins
- Adds shell command execution wrapper
- Refactors previous loader path
  * A './' path is unnecessary and will break calls to '/' path

container/src/root/macro/common/utility.hh

@@ -72,7 +72,7 @@ class Command final
   //! \brief Load given file path
   static void load(const std::string& path)
   {
-    std::string cmd{".L ./" + path};
+    std::string cmd{".L " + path};
     Command::cmd_handler({cmd});
   }
 
@@ -97,6 +97,15 @@ std::string get_env(const std::string& var)
   return std::string{env};
 }
 
+//! \brief Execute command in shell
+//! \param cmd Shell command [args]
+//! \returns Return value of command
+//! \since docker-finance 1.0.0
+int exec(const std::string& cmd)
+{
+  return gSystem->Exec(cmd.c_str());
+}
+
 //! \brief Make current timestamp
 //! \return timestamp in "yyyy-mm-ddThh:mm:ssZ" format
 //! \since docker-finance 1.0.0
@@ -140,6 +149,84 @@ void load(const std::initializer_list<std::string>& paths)
     common::Command::load(path);
 }
 }  // namespace macro
+
+//! \namespace docker_finance::plugin
+//! \brief docker-finance plugins
+//! \warning All plugins (repo/custom) must exist within this namespace
+//!          and work within their own inner namespace
+//! \since docker-finance 1.0.0
+namespace plugin
+{
+//! \brief Load plugin by pseudo-paths
+//! \details Wrapper to load from directory outside of default tree
+//! \param path Must be of string "repo/file" or "custom/file" where file is
+//!             a plugin filename that exists in repository plugin path or
+//!             a client-side end-user's custom plugin path.
+//! \ingroup cpp_plugin
+//! \details
+//!   Example:
+//!     <br>&emsp; root [0] docker_finance::plugin::load("repo/example.cc")<br>
+//!
+//!   Will load:
+//!     <br>&emsp; ${DOCKER_FINANCE_CONTAINER_REPO}/plugins/root/example.cc<br>
+//!
+//!   Example:
+//!     <br>&emsp; root [0] docker_finance::plugin::load("custom/example.cc")<br>
+//!
+//!   Will load:
+//!     <br>&emsp; ${DOCKER_FINANCE_CLIENT_PLUGINS}/root/example.cc<br>
+//!
+//! \note  Parent directory for all plugins are outside of repository's `root` directory
+void load(const std::string& path)
+{
+  const std::string type{path.substr(0, path.find("/"))};
+
+  std::string file{path};
+  file.erase(0, file.find("/") + 1);
+
+  if (type == "repo")
+    {
+      file.insert(
+          0,
+          macro::common::get_env("DOCKER_FINANCE_CONTAINER_REPO")
+              + "/plugins/root/");
+    }
+  else if (type == "custom")
+    {
+      file.insert(
+          0,
+          macro::common::get_env("DOCKER_FINANCE_CONTAINER_PLUGINS")
+              + "/root/");
+    }
+  else
+    {
+      throw std::runtime_error(
+          "must be of type 'repo/<file>' or 'custom/<file>'");
+    }
+
+  macro::common::Command::load(file);
+}
+
+//! \brief Wrapper to load plugins by list of pseudo-paths
+//! \ingroup cpp_plugin
+//! \param paths List must consist of string "repo/file" or "custom/file" where file is
+//!              a plugin filename that exists in repository plugin path or
+//!              a client-side end-user's custom plugin path.
+//! \details
+//!   Example:
+//!     <br>&emsp; root [0] docker_finance::plugin::load({"repo/example.cc", "custom/example.cc"})<br>
+//!
+//!   Will load:
+//!     <br>&emsp; ${DOCKER_FINANCE_CONTAINER_REPO}/plugins/root/example.cc
+//!                and ${DOCKER_FINANCE_CLIENT_PLUGINS}/root/example.cc<br>
+//!
+//! \note  Parent directory for all plugins are outside of repository's `root` directory
+void load(const std::initializer_list<std::string>& paths)
+{
+  for (const auto& path : paths)
+    macro::common::Command::load(path);
+}
+}  // namespace plugin
 }  // namespace docker_finance
 
 #endif  // CONTAINER_SRC_ROOT_MACRO_COMMON_UTILITY_HH_