Parse command line with boost program_options

cli/configuration.cpp

@@ -7,6 +7,7 @@ module;
 
 #include <string>
 #include <forward_list>
+#include <stdexcept>
 
 #include <toml.hpp>
 
@@ -15,8 +16,6 @@ import katja.repository;
 
 export module katja.configuration;
 
-import katja.component;
-
 export namespace katja
 {
     struct repository_configuration
@@ -58,17 +57,30 @@ export namespace katja
             return this->repositories.cend();
         }
     };
+
+    class configuration_error : public std::runtime_error
+    {
+    public:
+        configuration_error()
+            : std::runtime_error("Configuration is expected to be a table of repositories.")
+        {
+        }
+    };
 }
 
 TOML11_DEFINE_CONVERSION_NON_INTRUSIVE(katja::repository_configuration, path);
 
 export namespace katja
 {
-    configuration read_configuration()
+    configuration read_configuration(const std::string& configuration_file)
     {
-        auto raw_root = toml::parse("katja.toml");
+        auto raw_root = toml::parse(configuration_file);
         configuration result;
 
+        if (!raw_root.is_table())
+        {
+            throw configuration_error();
+        }
         for (const auto& [root_name, root_value] : raw_root.as_table())
         {
             auto repository_value = toml::get<repository_configuration>(root_value);