wrenpp/examples/cpp_calls/main.cpp

/* Copyright 2020-2024, Michele Santullo
 * This file is part of wrenpp.
 *
 * Wrenpp is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Wrenpp is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with wrenpp.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "wrenpp/vm_fun.hpp"
#include "wrenpp/def_configuration.hpp"
#include "wrenpp/callback_manager.hpp"
#include "wrenpp/class_manager.hpp"
#include <chrono>
#include <thread>
#include <iostream>

namespace {
constexpr char g_module_a[] =
"foreign class ClassA {" R"script(
	construct new(msg) {
		System.print("Wren ClassA constructed")
	}

	foreign say_hi()
}
)script";

constexpr char g_module_b[] = ""
R"script(
import "module_a" for ClassA

foreign class ClassB {
	construct new(nickname) {
		System.print("Wren ClassB constructed")
	}

	do_action(obj_a, times) {
		System.print("Wren ClassB is doing its action %(times) times...")
		for (z in 1..times) {
			obj_a.say_hi()
		}
		greeting_message("John", "Doe", "\\(O.O)/")
	}

	foreign greeting_message(first_name, family_name, emoji)
	foreign set_obj_c (obj)
	foreign get_obj_c()
}
)script";

constexpr char g_module_c[] =
"foreign class ClassC {" R"script(
	construct new (msg) {}
	foreign print_message()
}
)script";

//This is several examples in one:
//1. instantiate ClassA in Wren and pass it to do_action() which is a
//   non-foreign method in wren
//2. instantiate ClassA in C++, have C++ invoke the non-foreign method
//   do_action() on the object obj_b from the previous execution and pass the
//   C++ instance of ClassA to it
//3. instantiate ClassB in C++, have C++ invoke the non-foreign method
//   do_action() on it and pass the same ClassA instance from the previous
//   step to it
//4. show how to return a pre-existing instance of ClassC from ClassB both in
//   C++ and Wren
constexpr char g_script[] = ""
R"script(
import "module_a" for ClassA
import "module_b" for ClassB
import "module_c" for ClassC

var obj_b = ClassB.new("TheWren")
obj_b.do_action(ClassA.new("instanciated from script"), 2)
obj_b.greeting_message("Jane", "Doe", "ʕ·͡ᴥ·ʔ")

var obj_c = ClassC.new("Message of ClassC object instantiated in Wren")
obj_b.set_obj_c(obj_c)
obj_b.get_obj_c().print_message()
)script";

class MyWrenConfig : public wren::DefConfiguration {
public:
	char* load_module_fn (wren::VM* vm, std::string_view module_name) {
		if (module_name == "module_a")
			return copied(g_module_a, sizeof(g_module_a));
		else if (module_name == "module_b")
			return copied(g_module_b, sizeof(g_module_b));
		else if (module_name == "module_c")
			return copied(g_module_c, sizeof(g_module_c));
		return nullptr;
	}

	void load_module_complete_fn (wren::VM* vm, std::string_view module_name, char* buff) {
		static_cast<void>(vm);
		static_cast<void>(module_name);
		delete[] buff;
	}

private:
	char* copied (const char* source, std::size_t len) {
		char* const buff = new char[len];
		std::copy(source, source + len / sizeof(source[0]), buff);
		return buff;
	}
};

struct ClassA {
	explicit ClassA (std::string msg) : m_message(msg) {
		std::cout << "C++ ClassA constructed\n";
	}
	ClassA (const ClassA&) = delete;
	ClassA (ClassA&&) = delete;

	void say_hi() {
		std::cout << "C++ ClassA says \"" << m_message << "\"!\n";
	}

	std::string m_message;
};

class ClassC;

class ClassB {
public:
	explicit ClassB (std::string nickname) : m_nickname(nickname) {
		std::cout << "C++ ClassB constructed\n";
	}

	ClassB (const ClassB&) = delete;
	ClassB (ClassB&&) = delete;

	void greeting_message (
		std::string_view first_name,
		const char* family_name,
		const std::string& emoji
	) {
		std::cout << "C++ ClassB says \"hello " << first_name << " '"  <<
			m_nickname << "' " << family_name << "\" " << emoji << '\n';
	}

	void set_obj_c (wren::ForeignObject<ClassC> obj) {
		m_obj_c = std::move(obj);
	}
	wren::ForeignObject<ClassC>* get_obj_c() { return &m_obj_c; }

private:
	std::string m_nickname;
	wren::ForeignObject<ClassC> m_obj_c;
};

class ClassC {
public:
	ClassC (std::string msg) : m_message(msg) {}
	void print_message() const { std::cout << m_message << '\n'; }

private:
	std::string m_message;
};
} //unnamed namespace

int main() {
	using wren::make_function_bindable;
	using wren::make_foreign_class;
	using wren::make_wren_object;

	//We need a custom one to deal with custom module loading for
	//module_a and module_b
	MyWrenConfig config;
	wren::VM vm(&config, nullptr);


	vm.callback_manager()
		.add_callback(false, "module_a", "ClassA", "say_hi()", make_function_bindable<&ClassA::say_hi>)
		.add_callback(false, "module_b", "ClassB", "greeting_message(_,_,_)", make_function_bindable<&ClassB::greeting_message>)
		.add_callback(false, "module_b", "ClassB", "set_obj_c(_)", make_function_bindable<&ClassB::set_obj_c>)
		.add_callback(false, "module_b", "ClassB", "get_obj_c()", make_function_bindable<&ClassB::get_obj_c>)
		.add_callback(false, "module_c", "ClassC", "print_message()", make_function_bindable<&ClassC::print_message>)
	;
	vm.class_manager()
		.add_class_maker("module_b", "ClassB", make_foreign_class<ClassB, std::string>)
		.add_class_maker("module_a", "ClassA", make_foreign_class<ClassA, std::string>)
		.add_class_maker("module_c", "ClassC", make_foreign_class<ClassC, std::string>)
	;

	//Example 1: invoke obj_b.do_action() from Wren passing an obj_a that's
	//also instantiated from within the Wren script
	vm.interpret("main", g_script);

	//Example 2: invoke obj_b.do_action() from C++ passing a new obj_a which
	//is instantiated from C++
	wren::ForeignObject<ClassA> obj_a = make_wren_object<ClassA>(vm, wren::MN<"module_a", "ClassA">, "instantiated from c++");
	wren::call<void>(vm, wren::MN<"main", "obj_b">, "do_action", obj_a, 3);

	//Example 3: invoke obj_b.do_action() from C++, where obj_b is also
	//instantiated from C++, and pass the C++ obj_a instance to it
	auto obj_b = make_wren_object<ClassB>(vm, wren::MN<"module_b", "ClassB">, "TheCpp");
	wren::call<void>(vm, obj_b, "do_action", obj_a, 4);

	//Example 4: set obj_c on obj_c and query it back
	wren::ForeignObject<ClassC> obj_c = make_wren_object<ClassC>(vm, wren::MN<"module_c", "ClassC">, "Message of ClassC object instantiated in C++");
	obj_b.object().set_obj_c(std::move(obj_c));
	obj_b.object().get_obj_c()->object().print_message();

	std::cout << "Quitting in 1 sec" << std::endl;
	std::this_thread::sleep_for(std::chrono::milliseconds(1000));
	return 0;
}