lua_cArgParse

C++17, declarative arguments type checking, metaprogramming.

Applicability:

When writing C functions that are registered and called from Lua, it is often necessary to write checks on the received arguments against the required data types. By declaratively describing and passing parameter types to this library, it takes care of the bulk of these checks.

Basic example:

static int32_t test(lua_State* L) {
    std::tuple<std::variant<int32_t, std::string>, std::optional<float>> args;
    std::string errorStr;
    if (!utils::lua::cArgParse(L, args, errorStr)) {
        luaL_error(L, errorStr.c_str());
        return 0;
    }
    // Don't call lua_pop(L, lua_gettop(L)) - it's already in cArgParse.
    return process(args);
}
...
lua_register(L, "test", test);
assert(luaL_dostring(L, "test(123)") == LUA_OK);

More examples can be found in tests/test.cpp.

What's supported:

• std::tuple
• std::variant (cannot contain: std::optional, std::tuple, std::variant)
• std::optional
• (u)int(8|16|32|64)_t, float, double
• std::string
• std::vector (cannot contain: std::optional, std::tuple)
• std::map (cannot contain: std::optional, std::tuple)
• TODO: std::tuple in std::tuple
• TODO: maybe std::tuple in std::vector if std::vector not in std::variant
• TODO: use of Reflection far in the future

Principle of usage:

1. Describe the types of a function parameters in std::tuple or std::variant using supported constructs.
2. Call cArgParse with passing to it these std::tuple or std::variant and check the arguments parsing result through the returned ErrorString or Boolean. An empty ErrorString means successful parsing.
3. If there was a parsing error occured, handle the error string as you want - pass to luaL_error, pass to a logger, etc.