add config file reader-parser

cxx/tests/configfile_test.cpp

@@ -0,0 +1,39 @@
+#include <iostream>
+
+#include "../comm_server_configfile.h"
+
+
+
+int main(int argc, char* argv[])
+{
+    if (argc < 2) {
+        std::cout << "Usage: " << argv[0] << " cfg_filename\n";
+        return 1;
+    }
+
+    mcc::MccConfigfile cfg;
+
+    auto ec = cfg.load(std::string_view{argv[1]});
+    if (ec) {
+        std::cout << "ERR: " << ec.message() << "\n";
+        return 1;
+    }
+
+    for (auto& [key, v] : cfg.config()) {
+        std::cout << "<" << key << "> = ";
+        if (v.index()) {
+            if (v.index() > 1) {
+                for (auto& el : std::get<2>(v)) {
+                    std::cout << "<" << el << "> ";
+                }
+                std::cout << "\n";
+            } else {
+                std::cout << "<" << std::get<1>(v) << ">\n";
+            }
+        } else {
+            std::cout << "<no value>\n";
+        }
+    }
+
+    return 0;
+}