sol2/examples/customization.cpp
ThePhD 92a6fb8c11 update all the examples
fix implicitly convertible function pointers from classes using `call_detail`'s `lua_call_wrapper`
specificaly add documentation for working with `std::function`
2017-08-24 14:39:02 -04:00

100 lines
2.6 KiB
C++

#define SOL_CHECK_ARGUMENTS 1
#include <sol.hpp>
#include <iostream>
#include <iomanip>
#include <cassert>
struct two_things {
int a;
bool b;
};
namespace sol {
// First, the expected size
// Specialization of a struct
template <>
struct lua_size<two_things> : std::integral_constant<int, 2> {};
// Then, specialize the type
// this makes sure Sol can return it properly
template <>
struct lua_type_of<two_things> : std::integral_constant<sol::type, sol::type::poly> {};
// Now, specialize various stack structures
namespace stack {
template <>
struct checker<two_things> {
template <typename Handler>
static bool check(lua_State* L, int index, Handler&& handler, record& tracking) {
// indices can be negative to count backwards from the top of the stack,
// rather than the bottom up
// to deal with this, we adjust the index to
// its absolute position using the lua_absindex function
int absolute_index = lua_absindex(L, index);
// Check first and second second index for being the proper types
bool success = stack::check<int>(L, absolute_index, handler)
&& stack::check<bool>(L, absolute_index + 1, handler);
tracking.use(2);
return success;
}
};
template <>
struct getter<two_things> {
static two_things get(lua_State* L, int index, record& tracking) {
int absolute_index = lua_absindex(L, index);
// Get the first element
int a = stack::get<int>(L, absolute_index);
// Get the second element,
// in the +1 position from the first
bool b = stack::get<bool>(L, absolute_index + 1);
// we use 2 slots, each of the previous takes 1
tracking.use(2);
return two_things{ a, b };
}
};
template <>
struct pusher<two_things> {
static int push(lua_State* L, const two_things& things) {
int amount = stack::push(L, things.a);
// amount will be 1: int pushes 1 item
amount += stack::push(L, things.b);
// amount 2 now, since bool pushes a single item
// Return 2 things
return amount;
}
};
}
}
int main() {
std::cout << "=== customization example ===" << std::endl;
std::cout << std::boolalpha;
sol::state lua;
lua.open_libraries(sol::lib::base);
// Create a pass-through style of function
lua.script("function f ( a, b ) print(a, b) return a, b end");
// get the function out of Lua
sol::function f = lua["f"];
two_things things = f(two_things{ 24, false });
assert(things.a == 24);
assert(things.b == false);
// things.a == 24
// things.b == true
std::cout << "things.a: " << things.a << std::endl;
std::cout << "things.b: " << things.b << std::endl;
std::cout << std::endl;
return 0;
}