Parameters loaded from lua file without rebuilding

nufi/lua_config.h

@@ -0,0 +1,84 @@
+#pragma once
+
+#include <iostream>
+#include <stdexcept>
+#include <string>
+#include <variant>
+
+extern "C" {
+#include <lauxlib.h>
+#include <lua.h>
+#include <lualib.h>
+}
+
+using LuaValue = std::variant<int, float, bool, std::string>;
+
+class LuaConfig {
+public:
+  LuaConfig(const std::string &filePath, const std::string &tableName) {
+    L = luaL_newstate();
+    luaL_openlibs(L);
+
+    if (luaL_dofile(L, filePath.c_str()) != LUA_OK) {
+      std::string err = lua_tostring(L, -1);
+      lua_close(L);
+      throw std::runtime_error("Error loading Lua file: " + err);
+    }
+
+    lua_getglobal(L, tableName.c_str());
+    if (!lua_istable(L, -1)) {
+      lua_close(L);
+      throw std::runtime_error("'" + tableName +
+                               "' is not a table (or missing)");
+    }
+  }
+
+  ~LuaConfig() {
+    if (L)
+      lua_close(L);
+  }
+
+  LuaConfig(const LuaConfig &) = delete;
+  LuaConfig &operator=(const LuaConfig &) = delete;
+
+  template <typename T> T get(const std::string &key) const {
+    lua_getfield(L, -1, key.c_str());
+    if (lua_isnil(L, -1)) {
+      lua_pop(L, 1);
+      throw std::runtime_error("Missing key: " + key);
+    }
+    T value = extract<T>(key);
+    lua_pop(L, 1);
+    std::cout << "[LuaConfig] " << key << " = " << value << "\n";
+    return value;
+  }
+
+private:
+  lua_State *L = nullptr;
+
+  template <typename T> T extract(const std::string &key) const {
+    if constexpr (std::is_same_v<T, int>) {
+      if (!lua_isinteger(L, -1) && !lua_isnumber(L, -1))
+        throw std::runtime_error("Key '" + key + "' is not a number");
+      return static_cast<int>(lua_tointeger(L, -1));
+    } else if constexpr (std::is_same_v<T, float>) {
+      if (!lua_isnumber(L, -1))
+        throw std::runtime_error("Key '" + key + "' is not a number");
+      return static_cast<float>(lua_tonumber(L, -1));
+    } else if constexpr (std::is_same_v<T, double>) {
+      if (!lua_isnumber(L, -1))
+        throw std::runtime_error("Key '" + key + "' is not a number");
+      return static_cast<double>(lua_tonumber(L, -1));
+    } else if constexpr (std::is_same_v<T, bool>) {
+      if (!lua_isboolean(L, -1))
+        throw std::runtime_error("Key '" + key + "' is not a boolean");
+      return lua_toboolean(L, -1) != 0;
+    } else if constexpr (std::is_same_v<T, std::string>) {
+      if (!lua_isstring(L, -1))
+        throw std::runtime_error("Key '" + key + "' is not a string");
+      return std::string(lua_tostring(L, -1));
+    } else {
+      static_assert(!sizeof(T *), "Unsupported type for LuaConfig::get<T>()");
+    }
+  }
+};