sol2/test_functions.cpp

#define SOL_CHECK_ARGUMENTS

#include <catch.hpp>
#include <sol.hpp>
#include <iostream>
#include "test_stack_guard.hpp"

std::function<int()> makefn() {
    auto fx = []() -> int {
        return 0x1456789;
    };
    return fx;
}

void takefn(std::function<int()> purr) {
    if (purr() != 0x1456789)
        throw 0;
}

struct A {
    int a = 0xA; int bark() { return 1; }
};

std::tuple<int, int> bark(int num_value, A* a) {
    return std::tuple<int, int>(num_value * 2, a->bark());
}

void test_free_func(std::function<void()> f) {
    f();
}

void test_free_func2(std::function<int(int)> f, int arg1) {
    int val = f(arg1);
    if(val != arg1)
        throw sol::error("failed function call!");
}

int overloaded(int x) {
    std::cout << x << std::endl;
    return 3;
}

int overloaded(int x, int y) {
    std::cout << x << " " << y << std::endl;
    return 7;
}

int overloaded(int x, int y, int z) {
    std::cout << x << " " << y << " " << z << std::endl;
    return 11;
}

int non_overloaded(int x, int y, int z) {
    std::cout << x << " " << y << " " << z << std::endl;
    return 13;
}

namespace sep {
int plop_xyz(int x, int y, std::string z) {
    std::cout << x << " " << y << " " << z << std::endl;
    return 11;
}
}

TEST_CASE("functions/overload-resolution", "Check if overloaded function resolution templates compile/work") {
    sol::state lua;
    lua.open_libraries(sol::lib::base);

    lua.set_function("non_overloaded", non_overloaded);
    REQUIRE_NOTHROW(lua.script("x = non_overloaded(1, 2, 3)\nprint(x)"));

    /*
    // Cannot reasonably support: clang++ refuses to try enough
    // deductions to make this work
    lua.set_function<int>("overloaded", overloaded);
    REQUIRE_NOTHROW(lua.script("print(overloaded(1))"));

    lua.set_function<int, int>("overloaded", overloaded);
    REQUIRE_NOTHROW(lua.script("print(overloaded(1, 2))"));

    lua.set_function<int, int, int>("overloaded", overloaded);
    REQUIRE_NOTHROW(lua.script("print(overloaded(1, 2, 3))"));
    */
    lua.set_function("overloaded", sol::resolve<int(int)>(overloaded));
    REQUIRE_NOTHROW(lua.script("print(overloaded(1))"));

    lua.set_function("overloaded", sol::resolve<int(int, int)>(overloaded));
    REQUIRE_NOTHROW(lua.script("print(overloaded(1, 2))"));

    lua.set_function("overloaded", sol::resolve<int(int, int, int)>(overloaded));
    REQUIRE_NOTHROW(lua.script("print(overloaded(1, 2, 3))"));
}

TEST_CASE("functions/return-order-and-multi-get", "Check if return order is in the same reading order specified in Lua") {
    const static std::tuple<int, int, int> triple = std::make_tuple(10, 11, 12);
    const static std::tuple<int, float> paired = std::make_tuple(10, 10.f);
    sol::state lua;
    lua.set_function("f", [] {
        return std::make_tuple(10, 11, 12);
    } );
    int a = 0;
    lua.set_function( "h", []() {
        return std::make_tuple( 10, 10.0f );
    } );
    lua.script("function g() return 10, 11, 12 end\nx,y,z = g()");
    auto tcpp = lua.get<sol::function>("f").call<int, int, int>();
    auto tlua = lua.get<sol::function>( "g" ).call<int, int, int>();
    auto tcpp2 = lua.get<sol::function>( "h" ).call<int, float>();
    auto tluaget = lua.get<int, int, int>( "x", "y", "z" );
    REQUIRE(tcpp == triple);
    REQUIRE(tlua == triple);
    REQUIRE(tluaget == triple);
    REQUIRE(tcpp2 == paired);
}

TEST_CASE("functions/deducing-return-order-and-multi-get", "Check if return order is in the same reading order specified in Lua, with regular deducing calls") {
    const static std::tuple<int, int, int> triple = std::make_tuple(10, 11, 12);
    sol::state lua;
    lua.set_function( "f_string", []() { return "this is a string!"; } );
    sol::function f_string = lua[ "f_string" ];
    
    // Make sure there are no overload collisions / compiler errors for automatic string conversions
    std::string f_string_result = f_string();
    REQUIRE(f_string_result == "this is a string!");
    f_string_result = f_string();
    REQUIRE(f_string_result == "this is a string!");

    lua.set_function("f", [] {
        return std::make_tuple(10, 11, 12);
    });
    lua.script("function g() return 10, 11, 12 end\nx,y,z = g()");
    std::tuple<int, int, int> tcpp = lua.get<sol::function>("f")();
    std::tuple<int, int, int> tlua = lua.get<sol::function>("g")();
    std::tuple<int, int, int> tluaget = lua.get<int, int, int>("x", "y", "z");
    std::cout << "cpp: " << std::get<0>(tcpp) << ',' << std::get<1>(tcpp) << ',' << std::get<2>(tcpp) << std::endl;
    std::cout << "lua: " << std::get<0>(tlua) << ',' << std::get<1>(tlua) << ',' << std::get<2>(tlua) << std::endl;
    std::cout << "lua xyz: " << lua.get<int>("x") << ',' << lua.get<int>("y") << ',' << lua.get<int>("z") << std::endl;
    REQUIRE(tcpp == triple);
    REQUIRE(tlua == triple);
    REQUIRE(tluaget == triple);
}

TEST_CASE("functions/optional-values", "check if optionals can be passed in to be nil or otherwise") {
    sol::state lua;
    lua.script(R"( function f (a)
    return a
end )");

    sol::function lua_bark = lua["f"];
    
    sol::optional<int> testv = lua_bark(sol::optional<int>(29));
    sol::optional<int> testn = lua_bark(sol::nullopt);
    REQUIRE((bool)testv);
    REQUIRE_FALSE((bool)testn);
    REQUIRE(testv.value() == 29);
    int v = lua_bark(sol::optional<int>(29));
    REQUIRE_NOTHROW(sol::nil_t n = lua_bark(sol::nullopt));
    REQUIRE(v == 29);
}

TEST_CASE("functions/pair-and-tuple-and-proxy-tests", "Check if sol::reference and sol::proxy can be passed to functions as arguments") {
    sol::state lua;
    lua.new_usertype<A>("A",
        "bark", &A::bark);
    lua.script(R"( function f (num_value, a)
    return num_value * 2, a:bark()
end 
function h (num_value, a, b)
    return num_value * 2, a:bark(), b * 3
end 
nested = { variables = { no = { problem = 10 } } } )");
    lua.set_function("g", bark);

    sol::function cpp_bark = lua["g"];
    sol::function lua_bark = lua["f"];
    sol::function lua_bark2 = lua["h"];
    
    sol::reference lua_variable_x = lua["nested"]["variables"]["no"]["problem"];
    A cpp_variable_y;
    
    static const std::tuple<int, int> abdesired(20, 1);
    static const std::pair<int, int> cddesired = { 20, 1 };
    static const std::tuple<int, int, int> abcdesired(20, 1, 3);
    
    std::tuple<int, int> ab = cpp_bark(lua_variable_x, cpp_variable_y);
    std::pair<int, int> cd = lua_bark(lua["nested"]["variables"]["no"]["problem"], cpp_variable_y);

    REQUIRE(ab == abdesired);
    REQUIRE(cd == cddesired);

    ab = cpp_bark(std::make_pair(lua_variable_x, cpp_variable_y));
    cd = lua_bark(std::make_pair(lua["nested"]["variables"]["no"]["problem"], cpp_variable_y));

    REQUIRE(ab == abdesired);
    REQUIRE(cd == cddesired);

    std::tuple<int, int, int> abc = lua_bark2(std::make_tuple(10, cpp_variable_y), sol::optional<int>(1));
    REQUIRE(abc == abcdesired);
}

TEST_CASE("functions/sol::function-to-std::function", "check if conversion to std::function works properly and calls with correct arguments") {
    sol::state lua;
    lua.open_libraries(sol::lib::base);

    lua.set_function("testFunc", test_free_func);
    lua.set_function("testFunc2", test_free_func2);
    lua.script(
        "testFunc(function() print(\"hello std::function\") end)"
      );
    REQUIRE_NOTHROW(lua.script(
        "function m(a)\n"
        "     print(\"hello std::function with arg \", a)\n"
        "     return a\n"
        "end\n"
        "\n"
        "testFunc2(m, 1)"
     ));
}

TEST_CASE("functions/returning-functions-from-C++-and-gettin-in-lua", "check to see if returning a functor and getting a functor from lua is possible") {
    sol::state lua;
    lua.open_libraries(sol::lib::base);

    lua.set_function("makefn", makefn);
    lua.set_function("takefn", takefn);
    lua.script("afx = makefn()\n"
                "print(afx())\n"
                "takefn(afx)\n");
}

TEST_CASE( "functions/function_result-protected_function_result", "Function result should be the beefy return type for sol::function that allows for error checking and error handlers" ) {
    sol::state lua;
    lua.open_libraries( sol::lib::base, sol::lib::debug );
    static const char unhandlederrormessage[] = "true error message";
    static const char handlederrormessage[] = "doodle";
    static const std::string handlederrormessage_s = handlederrormessage;

    // Some function; just using a lambda to be cheap
    auto doomfx = []() {
        std::cout << "doomfx called" << std::endl;
        throw std::runtime_error( unhandlederrormessage );
    };
    auto luadoomfx = [&lua]() {
        std::cout << "luadoomfx called" << std::endl;
        // Does not bypass error function, will call it
        luaL_error( lua.lua_state(), unhandlederrormessage );
    };
    lua.set_function("doom", doomfx);
    lua.set_function("luadoom", luadoomfx);

    auto cpphandlerfx = []( std::string x ) {
        std::cout << "c++ handler called with: " << x << std::endl;
        return handlederrormessage;
    };
    lua.set_function( "cpphandler", cpphandlerfx );
    lua.script(
        std::string( "function luahandler ( message )" )
        + "    print('lua handler called with: ' .. message)"
        + "    return '" + handlederrormessage + "'"
        + "end"
        );
    auto nontrampolinefx = [](lua_State*) -> int { throw "x";};
    lua_CFunction c_nontrampolinefx = nontrampolinefx;
    lua.set("nontrampoline", c_nontrampolinefx);
    lua.set_function("bark", []() -> int {return 100;});

    sol::protected_function doom = lua[ "doom" ];
    sol::protected_function luadoom = lua["luadoom"];
    sol::protected_function nontrampoline = lua["nontrampoline"];
    sol::protected_function justfine = lua["bark"];
    sol::protected_function justfinewithhandler = lua["bark"];
    sol::function luahandler = lua["luahandler"];
    sol::function cpphandler = lua[ "cpphandler" ];
    doom.error_handler = luahandler;
    luadoom.error_handler = cpphandler;
    nontrampoline.error_handler = cpphandler;
    justfinewithhandler.error_handler = luahandler;
    bool present = true;
    {
        sol::protected_function_result result = doom();
        REQUIRE_FALSE(result.valid());
        sol::optional<sol::error> operr = result;
        sol::optional<int> opvalue = result;
        present = (bool)operr;
        REQUIRE(present);
        present = (bool)opvalue;
        REQUIRE_FALSE(present);
        sol::error err = result;
        REQUIRE(err.what() == handlederrormessage_s);
    }
    {
        sol::protected_function_result result = luadoom();
        REQUIRE_FALSE(result.valid());
        sol::optional<sol::error> operr = result;
        sol::optional<int> opvalue = result;
        present = (bool)operr;
        REQUIRE(present);
        present = (bool)opvalue;
        REQUIRE_FALSE(present);
        sol::error err = result;
        REQUIRE(err.what() == handlederrormessage_s);
    }
    {
        sol::protected_function_result result = nontrampoline();
        REQUIRE_FALSE(result.valid());
        sol::optional<sol::error> operr = result;
        sol::optional<int> opvalue = result;
        present = (bool)operr;
        REQUIRE(present);
        present = (bool)opvalue;
        REQUIRE_FALSE(present);
        sol::error err = result;
        REQUIRE(err.what() == handlederrormessage_s);
    }
    {
        sol::protected_function_result result = justfine();
        REQUIRE(result.valid());
        sol::optional<sol::error> operr = result;
        sol::optional<int> opvalue = result;
        present = (bool)operr;
        REQUIRE_FALSE(present);
        present = (bool)opvalue;
        REQUIRE(present);
        int value = result;
        REQUIRE(value == 100);
    }
    {
        sol::protected_function_result result = justfinewithhandler();
        REQUIRE(result.valid());
        sol::optional<sol::error> operr = result;
        sol::optional<int> opvalue = result;
        present = (bool)operr;
        REQUIRE_FALSE(present);
        present = (bool)opvalue;
        REQUIRE(present);
        int value = result;
        REQUIRE(value == 100);
    }
}

TEST_CASE("functions/destructor-tests", "Show that proper copies / destruction happens") {
    static int created = 0;
    static int destroyed = 0;
    static void* last_call = nullptr;
    static void* static_call = reinterpret_cast<void*>(0x01);
    typedef void(* fptr)();
    struct x { 
        x() {++created;}
        x(const x&) {++created;}
        x(x&&) {++created;}
        x& operator=(const x&) {return *this;}
        x& operator=(x&&) {return *this;}
        void func() {last_call = static_cast<void*>(this);};
        ~x () {++destroyed;} 
    };
    struct y { 
        y() {++created;}
        y(const x&) {++created;}
        y(x&&) {++created;}
        y& operator=(const x&) {return *this;}
        y& operator=(x&&) {return *this;}
        static void func() {last_call = static_call;};
        void operator()() {func();}
        operator fptr () { return func; }
        ~y () {++destroyed;} 
    };

    // stateful functors/member functions should always copy unless specified
    {
        created = 0;
        destroyed = 0;
        last_call = nullptr;
        {
            sol::state lua;
            x x1;
            lua.set_function("x1copy", &x::func, x1);
            lua.script("x1copy()");
            REQUIRE(created == 2);
            REQUIRE(destroyed == 0);
            REQUIRE_FALSE(last_call == &x1);

            lua.set_function("x1ref", &x::func, std::ref(x1));
            lua.script("x1ref()");
            REQUIRE(created == 2);
            REQUIRE(destroyed == 0);
            REQUIRE(last_call == &x1);
        }
        REQUIRE(created == 2);
        REQUIRE(destroyed == 2);
    }

    // things convertible to a static function should _never_ be forced to make copies
    // therefore, pass through untouched
    {
        created = 0;
        destroyed = 0;
        last_call = nullptr;
        {
            sol::state lua;
            y y1;
            lua.set_function("y1copy", y1);
            lua.script("y1copy()");
            REQUIRE(created == 1);
            REQUIRE(destroyed == 0);
            REQUIRE(last_call == static_call);
            
            last_call = nullptr;
            lua.set_function("y1ref", std::ref(y1));
            lua.script("y1ref()");
            REQUIRE(created == 1);
            REQUIRE(destroyed == 0);
            REQUIRE(last_call == static_call);
        }
        REQUIRE(created == 1);
        REQUIRE(destroyed == 1);
    }
}


TEST_CASE("functions/all-kinds", "Register all kinds of functions, make sure they all compile and work") {
    sol::state lua;

    struct test_1 {
        int a = 0xA;
        virtual int bark() {
            return a;
        }

        int bark_mem() {
            return a;
        }

        static std::tuple<int, int> x_bark(int num_value, test_1* a) {
            return std::tuple<int, int>(num_value * 2, a->a);
        }
    };

    struct test_2 {
        int a = 0xC;
        int bark() { 
            return 20; 
        }
    };

    auto a = []() { return 500; };
    auto b = [&]() { return 501; };
    auto c = [&]() { return 502; };
    auto d = []() { return 503; };

    lua.new_usertype<test_1>("test_1",
        "bark", sol::c_call<decltype(&test_1::bark_mem), &test_1::bark_mem>
        );
    lua.new_usertype<test_2>("test_2",
        "bark", sol::c_call<decltype(&test_2::bark), &test_2::bark>
        );
    test_2 t2;

    lua.set_function("a", a);
    lua.set_function("b", b);
    lua.set_function("c", std::ref(c));
    lua.set_function("d", std::ref(d));
    lua.set_function("f", &test_1::bark);
    lua.set_function("g", test_1::x_bark);
    lua.set_function("h", sol::c_call<decltype(&test_1::bark_mem), &test_1::bark_mem>);
    lua.set_function("i", &test_2::bark, test_2());
    lua.set_function("j", &test_2::a, test_2());
    lua.set_function("k", &test_2::a);
    lua.set_function("l", sol::c_call<decltype(&test_1::a), &test_1::a>);
    lua.set_function("m", &test_2::a, &t2);
    lua.set_function("n", sol::c_call<decltype(&test_1::x_bark), &test_1::x_bark>);
    lua.set_function("o", sol::c_call<decltype(test_1::x_bark), test_1::x_bark>);

    lua.script(R"(
o1 = test_1.new()
o2 = test_2.new()

ob = o1:bark()

A = a()
B = b()
C = c()
D = d()
F = f(o1)
G0, G1 = g(2, o1)
H = h(o1)
I = i(o1)
I = i(o1)

J0 = j()
j(24)
J1 = j()

K0 = k(o2)
k(o2, 1024)
K1 = k(o2)

L0 = l(o1)
l(o1, 678)
L1 = l(o1)


M0 = m()
m(256)
M1 = m()
    )");
    int ob, A, B, C, D, F, G0, G1, H, I, J0, J1, K0, K1, L0, L1, M0, M1;
    std::tie( ob, A, B, C, D, F, G0, G1, H, I, J0, J1, K0, K1, L0, L1, M0, M1 ) 
    = lua.get<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>(
        "ob", "A", "B", "C", "D", "F", "G0", "G1", "H", "I", "J0", "J1", "K0", "K1", "L0", "L1", "M0", "M1"
    );
   
    REQUIRE(ob == 0xA);
    
    REQUIRE( A == 500 );
    REQUIRE( B == 501 );
    REQUIRE( C == 502 );
    REQUIRE( D == 503 );

    REQUIRE( F == 0xA );
    REQUIRE( G0 == 4 );
    REQUIRE( G1 == 0xA );
    REQUIRE( H == 0xA );
    REQUIRE( I == 20 );

    REQUIRE( J0 == 0xC );
    REQUIRE( J1 == 24 );

    REQUIRE( K0 == 0xC );
    REQUIRE( K1 == 1024 );

    REQUIRE( L0 == 0xA );
    REQUIRE( L1 == 678 );

    REQUIRE( M0 == 0xC );
    REQUIRE( M1 == 256 );

    sol::bond( ob, A, B, C, D, F, G0, G1, H, I, J0, J1, K0, K1, L0, L1, M0, M1 ) 
    = lua.get<int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int>(
        "ob", "A", "B", "C", "D", "F", "G0", "G1", "H", "I", "J0", "J1", "K0", "K1", "L0", "L1", "M0", "M1"
    );
   
    REQUIRE(ob == 0xA);
    
    REQUIRE( A == 500 );
    REQUIRE( B == 501 );
    REQUIRE( C == 502 );
    REQUIRE( D == 503 );

    REQUIRE( F == 0xA );
    REQUIRE( G0 == 4 );
    REQUIRE( G1 == 0xA );
    REQUIRE( H == 0xA );
    REQUIRE( I == 20 );

    REQUIRE( J0 == 0xC );
    REQUIRE( J1 == 24 );

    REQUIRE( K0 == 0xC );
    REQUIRE( K1 == 1024 );

    REQUIRE( L0 == 0xA );
    REQUIRE( L1 == 678 );

    REQUIRE( M0 == 0xC );
    REQUIRE( M1 == 256 );
}

TEST_CASE("simple/call-with-parameters", "Lua function is called with a few parameters from C++") {
    sol::state lua;

    REQUIRE_NOTHROW(lua.script("function my_add(i, j, k) return i + j + k end"));
    auto f = lua.get<sol::function>("my_add");
    REQUIRE_NOTHROW(lua.script("function my_nothing(i, j, k) end"));
    auto fvoid = lua.get<sol::function>("my_nothing");
    int a;
    REQUIRE_NOTHROW(fvoid(1, 2, 3));
    REQUIRE_NOTHROW(a = f.call<int>(1, 2, 3));
    REQUIRE(a == 6);
    REQUIRE_THROWS(a = f(1, 2, "arf"));
}

TEST_CASE("simple/call-c++-function", "C++ function is called from lua") {
    sol::state lua;

    lua.set_function("plop_xyz", sep::plop_xyz);
    lua.script("x = plop_xyz(2, 6, 'hello')");

    REQUIRE(lua.get<int>("x") == 11);
}

TEST_CASE("simple/call-lambda", "A C++ lambda is exposed to lua and called") {
    sol::state lua;

    int a = 0;

    lua.set_function("foo", [&a] { a = 1; });

    lua.script("foo()");

    REQUIRE(a == 1);
}

TEST_CASE("advanced/get-and-call", "Checks for lambdas returning values after a get operation") {
    const static std::string lol = "lol", str = "str";
    const static std::tuple<int, float, double, std::string> heh_tuple = std::make_tuple(1, 6.28f, 3.14, std::string("heh"));
    sol::state lua;

    REQUIRE_NOTHROW(lua.set_function("a", [] { return 42; }));
    REQUIRE(lua.get<sol::function>("a").call<int>() == 42);

    REQUIRE_NOTHROW(lua.set_function("b", [] { return 42u; }));
    REQUIRE(lua.get<sol::function>("b").call<unsigned int>() == 42u);

    REQUIRE_NOTHROW(lua.set_function("c", [] { return 3.14; }));
    REQUIRE(lua.get<sol::function>("c").call<double>() == 3.14);

    REQUIRE_NOTHROW(lua.set_function("d", [] { return 6.28f; }));
    REQUIRE(lua.get<sol::function>("d").call<float>() == 6.28f);

    REQUIRE_NOTHROW(lua.set_function("e", [] { return "lol"; }));
    REQUIRE(lua.get<sol::function>("e").call<std::string>() == lol);

    REQUIRE_NOTHROW(lua.set_function("f", [] { return true; }));
    REQUIRE(lua.get<sol::function>("f").call<bool>());

    REQUIRE_NOTHROW(lua.set_function("g", [] { return std::string("str"); }));
    REQUIRE(lua.get<sol::function>("g").call<std::string>() == str);

    REQUIRE_NOTHROW(lua.set_function("h", [] { }));
    REQUIRE_NOTHROW(lua.get<sol::function>("h").call());

    REQUIRE_NOTHROW(lua.set_function("i", [] { return sol::nil; }));
    REQUIRE(lua.get<sol::function>("i").call<sol::nil_t>() == sol::nil);
    REQUIRE_NOTHROW(lua.set_function("j", [] { return std::make_tuple(1, 6.28f, 3.14, std::string("heh")); }));
    REQUIRE((lua.get<sol::function>("j").call<int, float, double, std::string>() == heh_tuple));
}

TEST_CASE("advanced/operator[]-call", "Checks for lambdas returning values using operator[]") {
    const static std::string lol = "lol", str = "str";
    const static std::tuple<int, float, double, std::string> heh_tuple = std::make_tuple(1, 6.28f, 3.14, std::string("heh"));
    sol::state lua;

    REQUIRE_NOTHROW(lua.set_function("a", [] { return 42; }));
    REQUIRE(lua["a"].call<int>() == 42);

    REQUIRE_NOTHROW(lua.set_function("b", [] { return 42u; }));
    REQUIRE(lua["b"].call<unsigned int>() == 42u);

    REQUIRE_NOTHROW(lua.set_function("c", [] { return 3.14; }));
    REQUIRE(lua["c"].call<double>() == 3.14);

    REQUIRE_NOTHROW(lua.set_function("d", [] { return 6.28f; }));
    REQUIRE(lua["d"].call<float>() == 6.28f);

    REQUIRE_NOTHROW(lua.set_function("e", [] { return "lol"; }));
    REQUIRE(lua["e"].call<std::string>() == lol);

    REQUIRE_NOTHROW(lua.set_function("f", [] { return true; }));
    REQUIRE(lua["f"].call<bool>());

    REQUIRE_NOTHROW(lua.set_function("g", [] { return std::string("str"); }));
    REQUIRE(lua["g"].call<std::string>() == str);

    REQUIRE_NOTHROW(lua.set_function("h", [] { }));
    REQUIRE_NOTHROW(lua["h"].call());

    REQUIRE_NOTHROW(lua.set_function("i", [] { return sol::nil; }));
    REQUIRE(lua["i"].call<sol::nil_t>() == sol::nil);
    REQUIRE_NOTHROW(lua.set_function("j", [] { return std::make_tuple(1, 6.28f, 3.14, std::string("heh")); }));
    REQUIRE((lua["j"].call<int, float, double, std::string>() == heh_tuple));
}

TEST_CASE("advanced/call-lambdas", "A C++ lambda is exposed to lua and called") {
    sol::state lua;

    int x = 0;
    lua.set_function("set_x", [&] (int new_x) {
        x = new_x;
        return 0;
    });

    lua.script("set_x(9)");
    REQUIRE(x == 9);
}

TEST_CASE("advanced/call-referenced_obj", "A C++ object is passed by pointer/reference_wrapper to lua and invoked") {
    sol::state lua;

    int x = 0;
    auto objx = [&](int new_x) {
        x = new_x;
        return 0;
    };
    lua.set_function("set_x", std::ref(objx));

    int y = 0;
    auto objy = [&](int new_y) {
        y = new_y;
        return std::tuple<int, int>(0, 0);
    };
    lua.set_function("set_y", &decltype(objy)::operator(), std::ref(objy));

    lua.script("set_x(9)");
    lua.script("set_y(9)");
    REQUIRE(x == 9);
    REQUIRE(y == 9);
}

TEST_CASE("functions/bond", "make sure advanced syntax with 'bond' works") {
    sol::state lua;

    lua.script(R"(function f () 
    return 1, 2, 3 
end)");
    sol::function f = lua["f"];

    int a, b, c;
    sol::bond(a, b, c) = f();
    REQUIRE(a == 1);
    REQUIRE(b == 2);
    REQUIRE(c == 3);
}