1 files changed, 87 insertions, 0 deletions
diff --git a/deps/sol2/examples/source/pairs_with_raw_functions.cpp b/deps/sol2/examples/source/pairs_with_raw_functions.cpp
new file mode 100644
index 0000000..cfb5af5
--- /dev/null
+++ b/deps/sol2/examples/source/pairs_with_raw_functions.cpp
@@ -0,0 +1,87 @@
+#define SOL_ALL_SAFETIES_ON 1
+#include <sol/sol.hpp>
+
+#include <map>
+#include <iostream>
+
+struct my_thing {
+	std::map<std::string, int> m{
+		{ "bark", 20 },
+		{ "woof", 60 },
+		{ "borf", 30 },
+		{ "awoo", 5 },
+	};
+
+	my_thing() {
+
+	}
+};
+
+struct lua_iterator_state {
+	typedef std::map<std::string, int>::iterator it_t;
+	it_t it;
+	it_t last;
+
+	lua_iterator_state(my_thing& mt) : it(mt.m.begin()), last(mt.m.end()) {}
+};
+
+int my_next(lua_State* L) {
+	// this gets called 
+	// to start the first iteration, and every
+	// iteration there after
+	// the state you passed in pairs is argument 1
+	// the key value is argument 2
+	// we do not care about the key value here
+	lua_iterator_state& it_state = sol::stack::get<sol::user<lua_iterator_state>>(L, 1);
+	auto& it = it_state.it;
+	if (it == it_state.last) {
+		return sol::stack::push(L, sol::lua_nil);
+	}
+	auto itderef = *it;
+	// 2 values are returned (pushed onto the stack):
+	// the key and the value
+	// the state is left alone
+	int pushed = sol::stack::push(L, itderef.first);
+	pushed += sol::stack::push_reference(L, itderef.second);
+	std::advance(it, 1);
+	return pushed;
+}
+
+int my_pairs(lua_State* L) {
+	my_thing& mt = sol::stack::get<my_thing>(L, 1);
+	lua_iterator_state it_state(mt);
+	// pairs expects 3 returns:
+	// the "next" function on how to advance,
+	// the "table" itself or some state,
+	// and an initial key value (can be nil)
+	
+	// next function controls iteration
+	int pushed = sol::stack::push(L, my_next);
+	pushed += sol::stack::push<sol::user<lua_iterator_state>>(L, std::move(it_state));
+	pushed += sol::stack::push(L, sol::lua_nil);
+	return pushed;
+}
+
+int main(int, char*[]) {
+	std::cout << "===== pairs (using raw Lua C functions) (advanced) =====" << std::endl;
+
+	sol::state lua;
+	lua.open_libraries(sol::lib::base);
+
+	lua.new_usertype<my_thing>("my_thing",
+		sol::meta_function::pairs, &my_pairs
+	);
+
+#if SOL_LUA_VERSION > 501
+	lua.safe_script(R"(
+local mt = my_thing.new()
+for k, v in pairs(mt) do 
+	print(k, v) 
+end
+)");
+#endif // Does not work on Lua 5.1 and below
+
+	std::cout << std::endl;
+
+	return 0;
+}