update docs a bit, think aobut changes to container_traits and friends...

docs/source/tutorial/all-the-things.rst

@@ -72,6 +72,9 @@ You can use the individual load and function call operator to load, check, and t
 	:linenos:
 	:lines: 1-10, 16-40, 47-49
 
+You can also `develop custom loaders`_ that pull from things that are not strings or files.
+
+
 set and get variables
 ---------------------
 
@@ -271,6 +274,7 @@ Some more things you can do/read about:
 	* :doc:`stack references<../api/stack_reference>` to have zero-overhead Sol abstractions while not copying to the Lua registry.
 	* :doc:`resolve<../api/resolve>` overloads in case you have overloaded functions; a cleaner casting utility. You must use this to emulate default parameters.
 
+.. _develop custom loaders: https://github.com/ThePhD/sol2/blob/develop/examples/custom_reader.cpp
 .. _basic example: https://github.com/ThePhD/sol2/blob/develop/examples/usertype.cpp
 .. _special functions example: https://github.com/ThePhD/sol2/blob/develop/examples/usertype_special_functions.cpp
 .. _initializers example: https://github.com/ThePhD/sol2/blob/develop/examples/usertype_initializers.cpp

examples/custom_reader.cpp

@@ -0,0 +1,95 @@
+#define SOL_CHECK_ARGUMENTS 1
+#include <sol.hpp>
+
+#include "assert.hpp"
+
+#include <iostream>
+#include <exception>
+#include <fstream>
+
+struct custom_reader {
+	FILE* f;
+	// We use 2 here to demonstrate
+	// multiple calls to the function to
+	// parse whole file.
+	// Please don't use 2.
+	// PLEASE DO NOT USE A BUFFER
+	// OF SIZE 2!
+	char buffer[2];
+	std::size_t current_size;
+	std::size_t read_count;
+
+	custom_reader(FILE* f_) : f(f_), buffer(), current_size(0), read_count(0) {
+
+	}
+
+	bool read() {
+		std::cout << "custom read: read #" << ++read_count << std::endl;
+		current_size = fread( buffer, 1, 2, f );
+		return current_size > 0 && ferror(f) == 0;
+	}
+
+	~custom_reader( ) {
+		std::fclose( f );
+	}
+};
+
+// function must match signature found in type lua_Reader:
+// const char* ( lua_State*, void*, size_t* )
+const char* custom_reader_function(lua_State*, void* pointer_to_my_object, size_t* data_size) {
+	custom_reader& cr = *(static_cast<custom_reader*>(pointer_to_my_object));
+	if ( cr.read( ) ) {
+		*data_size = cr.current_size;
+		return cr.buffer;
+	}
+	else {
+		*data_size = 0;
+		return nullptr;
+	}
+}
+
+int main( ) {
+	std::cout << "=== custom reader ===" << std::endl;
+
+	// make a file to use for the custom reader
+	{
+		std::ofstream bjork("bjork.lua", std::ios::binary);
+		bjork << "print('hello!')\n";
+	}
+	struct on_scope_exit {
+		~on_scope_exit() {
+			// remove file when done
+			std::remove("bjork.lua");
+		}
+	} remove_on_exit;
+
+
+	sol::state lua;
+	lua.open_libraries( sol::lib::base );
+
+	FILE* bjork_fp;
+#ifdef _MSC_VER
+	if ( fopen_s( &bjork_fp, "bjork.lua", "r" ) != 0 ) {
+		std::cerr << "failed to open bjork.lua -- exiting" << std::endl;
+		return -1;
+	}
+#else
+	bjork_fp = fopen( "bjork.lua", "r" );
+#endif
+	if (bjork_fp == nullptr) {
+		std::cerr << "failed to open bjork.lua -- exiting" << std::endl;
+		return -1;
+	}
+	custom_reader reader(bjork_fp);
+
+	// load the code using our custom reader, then run it
+	auto result = lua.safe_script( custom_reader_function, &reader, sol::script_pass_on_error );
+	// make sure we ran loaded and ran the code successfully
+	c_assert( result.valid( ) );
+
+	// note there are lua.load( ... ) variants that take a 
+	// custom reader than JUST run the code, too!
+
+	std::cout << std::endl;
+	return 0;
+}

examples/require_override_behavior.cpp

@@ -0,0 +1,76 @@
+// Thanks to OrfeasZ for their answer to
+// an issue for this example!
+#define SOL_CHECK_ARGUMENTS 1
+#include <sol.hpp>
+
+#include "assert.hpp"
+
+#include <iostream>
+#include <exception>
+
+// Use raw function of form "int(lua_State*)"
+// -- this is called a "raw C function",
+// and matches the type for lua_CFunction
+int LoadFileRequire(lua_State* L) {
+	// use sol2 stack API to pull
+	// "first argument"
+	std::string path = sol::stack::get<std::string>(L, 1);
+
+	if (path == "a") {
+		std::string script = R"(
+			print("Hello from module land!")
+			test = 123
+			return "bananas"
+		)";
+		// load "module", but don't run it
+		luaL_loadbuffer(L, script.data(), script.size(), path.c_str());
+		// returning 1 object left on Lua stack:
+		// a function that, when called, executes the script
+		// (this is what lua_loadX/luaL_loadX functions return
+		return 1;
+	}
+
+	sol::stack::push(L, "This is not the module you're looking for!");
+	return 1;
+}
+
+int main() {
+	std::cout << "=== require override behavior ===" << std::endl;
+
+	sol::state lua;
+	// need base for print,
+	// need package for package/searchers/require
+	lua.open_libraries(sol::lib::base, sol::lib::package);
+
+	lua.clear_package_loaders( );
+	lua.add_package_loader(LoadFileRequire);
+
+	// this will call our function for 
+	// the searcher and it will succeed
+	auto a_result = lua.safe_script(R"(
+		local a = require("a")
+		print(a)
+		print(test)
+	)", sol::script_pass_on_error);
+	c_assert(a_result.valid());
+	try {
+		// this will always fail
+		auto b_result = lua.safe_script(R"(
+			local b = require("b")
+			print(b)
+		)", sol::script_throw_on_error);
+		// this will not be executed because of the throw,
+		// but it better be true regardless!
+		c_assert(!b_result.valid());
+	}
+	catch (const std::exception& ex) {
+		// Whenever sol2 throws an exception from panic,
+		// catch
+		std::cout << "Something went wrong, as expected:\n" << ex.what() << std::endl;
+		// and CRASH / exit the application
+		return 0;
+	}
+
+	// If we get here something went wrong...!
+	return -1;
+}

sol/simple_usertype_metatable.hpp

@@ -332,7 +332,7 @@ namespace sol {
 				return;
 			}
 			mustindex = true;
-			(void)detail::swallow{0, ((detail::has_derived<Bases>::value = true), 0)...};
+			//(void)detail::swallow{0, ((detail::has_derived<Bases>::value = true), 0)...};
 
 			static_assert(sizeof(void*) <= sizeof(detail::inheritance_check_function), "The size of this data pointer is too small to fit the inheritance checking function: Please file a bug report.");
 			static_assert(sizeof(void*) <= sizeof(detail::inheritance_cast_function), "The size of this data pointer is too small to fit the inheritance checking function: Please file a bug report.");

sol/stack.hpp

@@ -220,6 +220,14 @@ namespace sol {
 			return call_syntax::colon;
 		}
 
+		inline void script(lua_State* L, lua_Reader reader, void* data, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+			detail::typical_chunk_name_t basechunkname = {};
+			const char* chunknametarget = detail::make_chunk_name("lua_Reader", chunkname, basechunkname);
+			if (lua_load(L, reader, data, chunknametarget, to_string(mode).c_str()) || lua_pcall(L, 0, LUA_MULTRET, 0)) {
+				lua_error(L);
+			}
+		}
+
 		inline void script(lua_State* L, const string_view& code, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
 			detail::typical_chunk_name_t basechunkname = {};
 			const char* chunknametarget = detail::make_chunk_name(code, chunkname, basechunkname);

sol/stack_push.hpp

@@ -169,7 +169,7 @@ namespace stack {
 			detail::unique_tag* id = nullptr;
 			Real* mem = detail::usertype_unique_allocate<P, Real>(L, pref, fx, id);
 			*fx = detail::usertype_unique_alloc_destroy<P, Real>;
-			*id = &detail::inheritance<P>::type_unique_cast<Real>;
+			*id = &detail::inheritance<P>::template type_unique_cast<Real>;
 			detail::default_construct::construct(mem, std::forward<Args>(args)...);
 			*pref = unique_usertype_traits<T>::get(*mem);
 			if (luaL_newmetatable(L, &usertype_traits<detail::unique_usertype<std::remove_cv_t<P>>>::metatable()[0]) == 1) {

sol/state_view.hpp

@@ -217,11 +217,74 @@ namespace sol {
 			return require_core(key, action, create_global);
 		}
 
+		void clear_package_loaders( ) {
+			optional<table> maybe_package = this->global["package"];
+			if (!maybe_package) {
+				// package lib wasn't opened
+				// open package lib
+				return;
+			}
+			table& package = *maybe_package;
+			// yay for version differences...
+			// one day Lua 5.1 will die a peaceful death
+			// and its old bones will find blissful rest
+			auto loaders_proxy = package
+#if SOL_LUA_VERSION < 502
+				["loaders"]
+#else
+				["searchers"]
+#endif
+				;
+			if (!loaders_proxy.valid()) {
+				// nothing to clear
+				return;
+			}
+			// we need to create the table for loaders
+			// table does not exist, so create and move forward
+			loaders_proxy = new_table(1, 0);
+		}
+
+		template <typename Fx>
+		void add_package_loader(Fx&& fx, bool clear_all_package_loaders = false) {
+			optional<table> maybe_package = this->global["package"];
+			if (!maybe_package) {
+				// package lib wasn't opened
+				// open package lib
+				return;
+			}
+			table& package = *maybe_package;
+			// yay for version differences...
+			// one day Lua 5.1 will die a peaceful death
+			// and its old bones will find blissful rest
+			auto loaders_proxy = package
+#if SOL_LUA_VERSION < 502
+			["loaders"]
+#else
+			["searchers"]
+#endif
+			;
+			bool make_new_table = clear_all_package_loaders || !loaders_proxy.valid( );
+			if (make_new_table) {
+				// we need to create the table for loaders
+				// table does not exist, so create and move forward
+				loaders_proxy = new_table(1, 0);
+			}
+			optional<table> maybe_loaders = loaders_proxy;
+			if (!maybe_loaders) {
+				// loaders/searches
+				// thing exists in package, but it
+				// ain't a table or a table-alike...!
+				return;
+			}
+			table loaders = loaders_proxy;
+			loaders.add(std::forward<Fx>(fx));
+		}
+
 		template <typename E>
-		protected_function_result do_string(const string_view& code, const basic_environment<E>& env, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+		protected_function_result do_reader(lua_Reader reader, void* data, const basic_environment<E>& env, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
 			detail::typical_chunk_name_t basechunkname = {};
-			const char* chunknametarget = detail::make_chunk_name(code, chunkname, basechunkname);
+			const char* chunknametarget = detail::make_chunk_name("lua_Reader", chunkname, basechunkname);
-			load_status x = static_cast<load_status>(luaL_loadbufferx(L, code.data(), code.size(), chunknametarget, to_string(mode).c_str()));
+			load_status x = static_cast<load_status>(lua_load(L, reader, data, chunknametarget, to_string(mode).c_str()));
 			if (x != load_status::ok) {
 				return protected_function_result(L, absolute_index(L, -1), 0, 1, static_cast<call_status>(x));
 			}
@@ -230,9 +293,22 @@ namespace sol {
 			return pf();
 		}
 
+		protected_function_result do_reader(lua_Reader reader, void* data, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+			detail::typical_chunk_name_t basechunkname = {};
+			const char* chunknametarget = detail::make_chunk_name("lua_Reader", chunkname, basechunkname);
+			load_status x = static_cast<load_status>(lua_load(L, reader, data, chunknametarget, to_string(mode).c_str()));
+			if (x != load_status::ok) {
+				return protected_function_result(L, absolute_index(L, -1), 0, 1, static_cast<call_status>(x));
+			}
+			stack_aligned_protected_function pf(L, -1);
+			return pf();
+		}
+
 		template <typename E>
-		protected_function_result do_file(const std::string& filename, const basic_environment<E>& env, load_mode mode = load_mode::any) {
+		protected_function_result do_string(const string_view& code, const basic_environment<E>& env, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
-			load_status x = static_cast<load_status>(luaL_loadfilex(L, filename.c_str(), to_string(mode).c_str()));
+			detail::typical_chunk_name_t basechunkname = {};
+			const char* chunknametarget = detail::make_chunk_name(code, chunkname, basechunkname);
+			load_status x = static_cast<load_status>(luaL_loadbufferx(L, code.data(), code.size(), chunknametarget, to_string(mode).c_str()));
 			if (x != load_status::ok) {
 				return protected_function_result(L, absolute_index(L, -1), 0, 1, static_cast<call_status>(x));
 			}
@@ -252,6 +328,17 @@ namespace sol {
 			return pf();
 		}
 
+		template <typename E>
+		protected_function_result do_file(const std::string& filename, const basic_environment<E>& env, load_mode mode = load_mode::any) {
+			load_status x = static_cast<load_status>(luaL_loadfilex(L, filename.c_str(), to_string(mode).c_str()));
+			if (x != load_status::ok) {
+				return protected_function_result(L, absolute_index(L, -1), 0, 1, static_cast<call_status>(x));
+			}
+			stack_aligned_protected_function pf(L, -1);
+			set_environment(env, pf);
+			return pf();
+		}
+
 		protected_function_result do_file(const std::string& filename, load_mode mode = load_mode::any) {
 			load_status x = static_cast<load_status>(luaL_loadfilex(L, filename.c_str(), to_string(mode).c_str()));
 			if (x != load_status::ok) {
@@ -261,6 +348,19 @@ namespace sol {
 			return pf();
 		}
 
+		template <typename Fx, meta::disable_any<meta::is_string_constructible<meta::unqualified_t<Fx>>, meta::is_specialization_of<meta::unqualified_t<Fx>, basic_environment>> = meta::enabler>
+		protected_function_result safe_script(lua_Reader reader, void* data, Fx&& on_error, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+			protected_function_result pfr = do_reader(reader, data, chunkname, mode);
+			if (!pfr.valid()) {
+				return on_error(L, std::move(pfr));
+			}
+			return pfr;
+		}
+
+		protected_function_result safe_script(lua_Reader reader, void* data, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+			return safe_script(reader, data, script_default_on_error, chunkname, mode);
+		}
+
 		template <typename Fx, meta::disable_any<meta::is_string_constructible<meta::unqualified_t<Fx>>, meta::is_specialization_of<meta::unqualified_t<Fx>, basic_environment>> = meta::enabler>
 		protected_function_result safe_script(const string_view& code, Fx&& on_error, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
 			protected_function_result pfr = do_string(code, chunkname, mode);
@@ -315,6 +415,31 @@ namespace sol {
 			return safe_script_file(filename, script_default_on_error, mode);
 		}
 
+		template <typename E>
+		unsafe_function_result unsafe_script(lua_Reader reader, void* data, const basic_environment<E>& env, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+			detail::typical_chunk_name_t basechunkname = {};
+			const char* chunknametarget = detail::make_chunk_name("lua_Reader", chunkname, basechunkname);
+			int index = lua_gettop(L);
+			if (lua_load(L, reader, data, chunknametarget, to_string(mode).c_str())) {
+				lua_error(L);
+			}
+			set_environment(env, stack_reference(L, raw_index(index + 1)));
+			if (lua_pcall(L, 0, LUA_MULTRET, 0)) {
+				lua_error(L);
+			}
+			int postindex = lua_gettop(L);
+			int returns = postindex - index;
+			return unsafe_function_result(L, (std::max)(postindex - (returns - 1), 1), returns);
+		}
+
+		unsafe_function_result unsafe_script(lua_Reader reader, void* data, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+			int index = lua_gettop(L);
+			stack::script(L, reader, data, chunkname, mode);
+			int postindex = lua_gettop(L);
+			int returns = postindex - index;
+			return unsafe_function_result(L, (std::max)(postindex - (returns - 1), 1), returns);
+		}
+
 		template <typename E>
 		unsafe_function_result unsafe_script(const string_view& code, const basic_environment<E>& env, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
 			detail::typical_chunk_name_t basechunkname = {};
@@ -392,6 +517,10 @@ namespace sol {
 		}
 
 #if defined(SOL_SAFE_FUNCTION) && SOL_SAFE_FUNCTION
+		protected_function_result script(lua_Reader reader, void* data, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
+			return safe_script(reader, data, chunkname, mode);
+		}
+
 		protected_function_result script(const string_view& code, const std::string& chunkname = detail::default_chunk_name(), load_mode mode = load_mode::any) {
 			return safe_script(code, chunkname, mode);
 		}
@@ -448,6 +577,12 @@ namespace sol {
 		}
 
 		global_table globals() const {
+			// if we return a reference 
+			// we'll be screwed a bit
+			return global;
+		}
+
+		global_table& globals() {
 			return global;
 		}
 

tests/test_customizations.cpp

@@ -147,7 +147,7 @@ TEST_CASE("customization/split struct", "using the newly documented customizatio
 	REQUIRE(d == 36.5);
 }
 
-TEST_CASE("customization/get_ check_usertype", "using the newly documented customization points to handle different kinds of classes") {
+TEST_CASE("customization/usertype", "using the newly documented customization points to handle different kinds of classes") {
 	sol::state lua;
 
 	// Create a pass-through style of function
@@ -168,3 +168,17 @@ TEST_CASE("customization/get_ check_usertype", "using the newly documented custo
 	REQUIRE(thingsf.num == 25);
 	REQUIRE(thingsg.num == 35);
 }
+
+TEST_CASE("customization/overloading", "using multi-size customized types in an overload") {
+	bool TwoThingsWorks = false, OverloadWorks = false;
+	sol::state lua;
+	lua["test_two_things"] = [&](two_things) { TwoThingsWorks = true; };
+	lua["test_overload"] = sol::overload([&](two_things) { OverloadWorks = true; }, [] {});
+
+	lua.script(
+		"test_two_things(0, true)\n"
+		"test_overload(0, true)");
+
+	REQUIRE(TwoThingsWorks);
+	REQUIRE(OverloadWorks);
+}