Fix race between killing object and drawing object

[lsnes.git] / include / library / lua-class.hpp

#ifndef _library__lua_class__hpp__included__
#define _library__lua_class__hpp__included__

#include "lua-base.hpp"
#include "lua-pin.hpp"

namespace lua
{
class class_base;
class parameters;

/**
 * Group of classes.
 */
class class_group
{
public:
/**
 * Create a group.
 */
        class_group();
/**
 * Destroy a group.
 */
        ~class_group();
/**
 * Add a class to group.
 */
        void do_register(const std::string& name, class_base& fun);
/**
 * Drop a class from group.
 */
        void do_unregister(const std::string& name, class_base& fun);
/**
 * Request callbacks on all currently registered functions.
 */
        void request_callback(std::function<void(std::string, class_base*)> cb);
/**
 * Bind a callback.
 *
 * Callbacks for all registered functions are immediately called.
 */
        int add_callback(std::function<void(std::string, class_base*)> cb,
                std::function<void(class_group*)> dcb);
/**
 * Unbind a calback.
 */
        void drop_callback(int handle);
private:
        char dummy;
};

struct class_ops
{
        bool (*is)(state& _state, int index);
        const std::string& (*name)();
        std::string (*print)(state& _state, int index);
};

std::list<class_ops>& userdata_recogn_fns();
std::string try_recognize_userdata(state& _state, int index);
std::string try_print_userdata(state& _state, int index);
std::unordered_map<std::type_index, void*>& class_types();

/**
 * Helper class containing binding data for Lua class call.
 */
template<class T> struct class_binding
{
/**
 * The pointer to call.
 */
        int (T::*fn)(state& lstate, lua::parameters& P);
/**
 * The state to call it in.
 */
        state* _state;
/**
 * The name of the method to pass.
 */
        char fname[];
};

/**
 * Helper class containing binding data for Lua static class call.
 */
struct static_binding
{
/**
 * The pointer to call.
 */
        int (*fn)(state& lstate, parameters& P);
/**
 * The state to call it in.
 */
        state* _state;
/**
 * The name of the method to pass.
 */
        char fname[];
};

template<class T> class _class;

/**
 * Function to obtain class object for given Lua class.
 */
template<class T> _class<T>& objclass()
{
        auto& type = typeid(T);
        if(!class_types().count(type))
                throw std::runtime_error("Internal error: Lua class not found!");
        return *reinterpret_cast<_class<T>*>(class_types()[type]);
}

/**
 * A class method.
 */
template<class T> struct class_method
{
/**
 * Name.
 */
        const char* name;
/**
 * Function.
 */
        int (T::*fn)(state& LS, lua::parameters& P);
};

/**
 * A static class method.
 */
struct static_method
{
/**
 * Name.
 */
        const char* name;
/**
 * Function.
 */
        int (*fn)(state& LS, parameters& P);
};

/**
 * Virtual base of Lua classes
 */
class class_base
{
public:
/**
 * Create a new Lua class.
 *
 * Parameter _group: The group the class will be in.
 * Parameter _name: The name of the class.
 */
        class_base(class_group& _group, const std::string& _name);
/**
 * Dtor.
 */
        virtual ~class_base() throw();
/**
 * Lookup by name in given Lua state.
 *
 * Parameter _L: The Lua state to look in.
 * Parameter _name: The name of the class.
 * Returns: The class instance, or NULL if no match.
 */
        static class_base* lookup(state& L, const std::string& _name);
/**
 * Push class table to stack.
 */
        static bool lookup_and_push(state& L, const std::string& _name);
/**
 * Get set of all classes.
 */
        static std::set<std::string> all_classes(state& L);
/**
 * Register in given Lua state.
 */
        virtual void register_state(state& L) = 0;
/**
 * Lookup static methods in class.
 */
        virtual std::list<static_method> static_methods() = 0;
/**
 * Lookup class methods in class.
 */
        virtual std::set<std::string> class_methods() = 0;
/**
 * Get name of class.
 */
        const std::string& get_name() { return name; }
protected:
        void delayed_register();
        void register_static(state& L);
private:
        class_group& group;
        std::string name;
        bool registered;
};

static const size_t overcommit_std_align = 32;

/**
 * Align a overcommit pointer.
 */
template<typename T, typename U> U* align_overcommit(T* th)
{
        size_t ptr = reinterpret_cast<size_t>(th) + sizeof(T);
        return reinterpret_cast<U*>(ptr + (overcommit_std_align - ptr % overcommit_std_align) % overcommit_std_align);
}

/**
 * The type of Lua classes.
 */
template<class T> class _class : public class_base
{
        template<typename... U> T* _create(state& _state, U... args)
        {
                size_t overcommit = T::overcommit(args...);
                void* obj = _state.newuserdata(sizeof(T) + overcommit);
                load_metatable(_state);
                _state.setmetatable(-2);
                T* _obj = reinterpret_cast<T*>(obj);
                try {
                        new(_obj) T(_state, args...);
                } catch(...) {
                        //CTOR FAILED. Get rid of the dtor (since it would error) and then dump the object.
                        _state.newtable();
                        _state.setmetatable(-2);
                        _state.pop(1);
                        throw;
                }
                return _obj;
        }

        static int class_bind_trampoline(lua_State* LS)
        {
                try {
                        class_binding<T>* b = (class_binding<T>*)lua_touserdata(LS, lua_upvalueindex(1));
                        state L(*b->_state, LS);
                        T* p = _class<T>::get(L, 1, b->fname);
                        lua::parameters P(L, b->fname);
                        return (p->*(b->fn))(L, P);
                } catch(std::exception& e) {
                        std::string err = e.what();
                        lua_pushlstring(LS, err.c_str(), err.length());
                        lua_error(LS);
                }
                return 0; //NOTREACHED
        }

        T* _get(state& _state, int arg, const std::string& fname, bool optional = false)
        {
                if(_state.type(arg) == LUA_TNONE || _state.type(arg) == LUA_TNIL) {
                        if(optional)
                                return NULL;
                        else
                                goto badtype;
                }
                load_metatable(_state);
                if(!_state.getmetatable(arg))
                        goto badtype;
                if(!_state.rawequal(-1, -2))
                        goto badtype;
                _state.pop(2);
                return reinterpret_cast<T*>(_state.touserdata(arg));
badtype:
                (stringfmt() << "argument #" << arg << " to " << fname << " must be " << name).throwex();
                return NULL;    //Never reached.
        }

        bool _is(state& _state, int arg)
        {
                if(_state.type(arg) != LUA_TUSERDATA)
                        return false;
                load_metatable(_state);
                if(!_state.getmetatable(arg)) {
                        _state.pop(1);
                        return false;
                }
                bool ret = _state.rawequal(-1, -2);
                _state.pop(2);
                return ret;
        }

        objpin<T> _pin(state& _state, int arg, const std::string& fname)
        {
                T* obj = get(_state, arg, fname);
                _state.pushvalue(arg);
                objpin<T> t(_state, obj);
                _state.pop(1);
                return t;
        }

        void bind(state& _state, const char* keyname, int (T::*fn)(state& LS, lua::parameters& P))
        {
                load_metatable(_state);
                _state.pushstring(keyname);
                std::string fname = name + std::string("::") + keyname;
                void* ptr = _state.newuserdata(sizeof(class_binding<T>) + fname.length() + 1);
                class_binding<T>* bdata = reinterpret_cast<class_binding<T>*>(ptr);
                bdata->fn = fn;
                bdata->_state = &_state.get_master();
                std::copy(fname.begin(), fname.end(), bdata->fname);
                bdata->fname[fname.length()] = 0;
                _state.pushcclosure(class_bind_trampoline, 1);
                _state.rawset(-3);
                _state.pop(1);
        }
protected:
        void register_state(state& L)
        {
                static char once_key;
                register_static(L);
                if(L.do_once(&once_key))
                        for(auto i : cmethods)
                                bind(L, i.name, i.fn);
        }
public:
/**
 * Create a new Lua class.
 *
 * Parameter _group: The group the class will be in.
 * Parameter _name: The name of the class.
 * Parameter _smethods: Static methods of the class.
 * Parameter _cmethods: Class methods of the class.
 * Parameter _print: The print method.
 */
        _class(class_group& _group, const std::string& _name, std::initializer_list<static_method> _smethods,
                std::initializer_list<class_method<T>> _cmethods = {}, std::string (T::*_print)() = NULL)
                : class_base(_group, _name), smethods(_smethods), cmethods(_cmethods)
        {
                name = _name;
                class_ops m;
                printmeth = _print;
                m.is = _class<T>::is;
                m.name = _class<T>::get_name;
                m.print = _class<T>::print;
                userdata_recogn_fns().push_back(m);
                auto& type = typeid(T);
                class_types()[type] = this;
                delayed_register();
        }
/**
 * Dtor
 */
        ~_class() throw()
        {
                auto& type = typeid(T);
                class_types().erase(type);
                auto& fns = userdata_recogn_fns();
                for(auto i = fns.begin(); i != fns.end(); i++) {
                        if(i->is == _class<T>::is) {
                                fns.erase(i);
                                break;
                        }
                }
        }
/**
 * Create a new instance of object.
 *
 * Parameter _state: The Lua state to create the object in.
 * Parameter args: The arguments to pass to class constructor.
 */
        template<typename... U> static T* create(state& _state, U... args)
        {
                return objclass<T>()._create(_state, args...);
        }

/**
 * Get a pointer to the object.
 *
 * Parameter _state: The Lua state.
 * Parameter arg: Argument index.
 * Parameter fname: The name of function for error messages.
 * Parameter optional: If true and argument is NIL or none, return NULL.
 * Throws std::runtime_error: Wrong type.
 */
        static T* get(state& _state, int arg, const std::string& fname, bool optional = false)
                throw(std::bad_alloc, std::runtime_error)
        {
                return objclass<T>()._get(_state, arg, fname, optional);
        }

/**
 * Identify if object is of this type.
 *
 * Parameter _state: The Lua state.
 * Parameter arg: Argument index.
 * Returns: True if object is of specified type, false if not.
 */
        static bool is(state& _state, int arg) throw()
        {
                try {
                        return objclass<T>()._is(_state, arg);
                } catch(...) {
                        return false;
                }
        }
/**
 * Get name of class.
 */
        static const std::string& get_name()
        {
                try {
                        return objclass<T>().name;
                } catch(...) {
                        static std::string foo = "???";
                        return foo;
                }
        }
/**
 * Format instance of this class as string.
 */
        static std::string print(state& _state, int index)
        {
                T* obj = get(_state, index, "__internal_print");
                try {
                        auto pmeth = objclass<T>().printmeth;
                        if(pmeth)
                                return (obj->*pmeth)();
                        else
                                return "";
                } catch(...) {
                        return "";
                }
        }
/**
 * Get a pin of object against Lua GC.
 *
 * Parameter _state: The Lua state.
 * Parameter arg: Argument index.
 * Parameter fname: Name of function for error message purposes.
 * Throws std::runtime_error: Wrong type.
 */
        static objpin<T> pin(state& _state, int arg, const std::string& fname) throw(std::bad_alloc,
                std::runtime_error)
        {
                return objclass<T>()._pin(_state, arg, fname);
        }
/**
 * Lookup static methods.
 */
        std::list<static_method> static_methods()
        {
                return smethods;
        }
/**
 * Lookup class methods.
 */
        std::set<std::string> class_methods()
        {
                std::set<std::string> r;
                for(auto& i : cmethods)
                        r.insert(i.name);
                return r;
        }
private:
        static int dogc(lua_State* LS)
        {
                T* obj = reinterpret_cast<T*>(lua_touserdata(LS, 1));
                obj->~T();
                return 0;
        }

        static int newindex(lua_State* LS)
        {
                lua_pushstring(LS, "Writing metatables of classes is not allowed");
                lua_error(LS);
                return 0;
        }

        static int index(lua_State* LS)
        {
                lua_getmetatable(LS, 1);
                lua_pushvalue(LS, 2);
                lua_rawget(LS, -2);
                if(lua_type(LS, -1) == LUA_TNIL) {
                        std::string err = std::string("Class '") + lua_tostring(LS, lua_upvalueindex(1)) +
                                "' does not have class method '" + lua_tostring(LS, 2) + "'";
                        lua_pushstring(LS, err.c_str());
                        lua_error(LS);
                }
                return 1;
        }

        void load_metatable(state& _state)
        {
again:
                _state.pushlightuserdata(this);
                _state.rawget(LUA_REGISTRYINDEX);
                if(_state.type(-1) == LUA_TNIL) {
                        _state.pop(1);
                        _state.pushlightuserdata(this);
                        _state.newtable();
                        _state.pushvalue(-1);
                        _state.setmetatable(-2);
                        _state.pushstring("__gc");
                        _state.pushcfunction(&_class<T>::dogc);
                        _state.rawset(-3);
                        _state.pushstring("__newindex");
                        _state.pushcfunction(&_class<T>::newindex);
                        _state.rawset(-3);
                        _state.pushstring("__index");
                        _state.pushlstring(name);
                        _state.pushcclosure(&_class<T>::index, 1);
                        _state.rawset(-3);
                        _state.rawset(LUA_REGISTRYINDEX);
                        goto again;
                }
        }
        std::string name;
        std::list<static_method> smethods;
        std::list<class_method<T>> cmethods;
        std::string (T::*printmeth)();
        _class(const _class<T>&);
        _class& operator=(const _class<T>&);
};
}

#endif