sol2/examples/source/containers_as_table.cpp

#define SOL_ALL_SAFETIES_ON 1
#include <sol/sol.hpp>

#include <vector>
#include <map>
#include "assert.hpp"
#include <iostream>


// nested allows serialization of maps with vectors inside, and vice-versa
// all from a nested structure of Lua tables
// it has less control over which pieces are considered tables in Lua,
// and which ones are considered userdata, but it covers a good 90% of cases
// where someone wants to handle a nested table
void demo(sol::nested<std::map<std::string, std::vector<std::string>>> src) {
	std::cout << "demo, sol::nested<...>" << std::endl;
	const auto& listmap = src.value();
	c_assert(listmap.size() == 2);
	for (const auto& kvp : listmap) {
		const std::vector<std::string>& strings = kvp.second;
		c_assert(strings.size() == 3);
		std::cout << "\t" << kvp.first << " = ";
		for (const auto& s : strings) {
			std::cout << "'" << s << "'" << " ";
		}
		std::cout << std::endl;
	}
	std::cout << std::endl;
}

// This second demo is equivalent to the first
// Nota bene the signature here
// Every container-type that's meant to be 
// a table must be wrapped in `sol::as_table_t`
// it's verbose, so feel free to use typedefs to make it easy on you
// you can mix which parts are considered tables from Lua, and which parts
// are considered other kinds of types, such as userdata and the like
void demo_explicit (sol::as_table_t<std::map<std::string, sol::as_table_t<std::vector<std::string>>>> src) {
	std::cout << "demo, explicit sol::as_table_t<...>" << std::endl;
	// Have to access the "source" member variable for as_table_t
	const auto& listmap = src.value();
	c_assert(listmap.size() == 2);
	for (const auto& kvp : listmap) {
		// Have to access the internal "source" for the inner as_table_t, as well
		const std::vector<std::string>& strings = kvp.second.value();
		c_assert(strings.size() == 3);
		std::cout << "\t" << kvp.first << " = ";
		for (const auto& s : strings) {
			std::cout << "'" << s << "'" << " ";
		}
		std::cout << std::endl;
	}
	std::cout << std::endl;
}

int main(int, char**) {
	std::cout << "=== containers retrieved from lua tables ===" << std::endl;
	
	sol::state lua;
	// bind the function
	lua.set_function("f", &demo);
	lua.set_function("g", &demo_explicit);
	// Call it with a table that has string sequences set to distinct keys
	lua.script(R"(
t = { 
	key1 = {'hello', 'there', 'world'},
	key2 = {'bark', 'borf', 'woof'}
}
f(t)
g(t)
	)");

	std::cout << std::endl;

	return 0;
}