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ScriptUserData.h
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ScriptUserData.h
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/*
* Copyright (C) 2012 Me and My Shadow
*
* This file is part of Me and My Shadow.
*
* Me and My Shadow 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.
*
* Me and My Shadow 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 Me and My Shadow. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef SCRIPTUSERDATA_H
#define SCRIPTUSERDATA_H
extern "C" {
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
}
#include <string>
#include <memory>
#include <assert.h>
//NOTE: Enable this you'll see a lot of annoying script debug messages which will lag the game.
//#define DISABLED_DEBUG_STUFF
#if defined(DISABLED_DEBUG_STUFF)
//Some debug functions
void scriptUserClassDebugCreate(char sig1,char sig2,char sig3,char sig4,const void* p1,const void* p2);
void scriptUserClassDebugInvalidate(char sig1,char sig2,char sig3,char sig4,const void* p1,const void* p2);
void scriptUserClassDebugUnlink(char sig1,char sig2,char sig3,char sig4,const void* p1,const void* p2);
#endif
//A struct represents the Lua user data.
struct ScriptUserData{
char sig1,sig2,sig3,sig4;
void* data;
ScriptUserData* prev;
ScriptUserData* next;
};
//A helper class to bind C++ class to Lua user data.
template<char sig1,char sig2,char sig3,char sig4,class T>
class ScriptUserClass{
public:
ScriptUserClass():scriptUserDataHead(NULL){
}
ScriptUserClass(const ScriptUserClass& other) = delete;
ScriptUserClass& operator=(const ScriptUserClass& other) = delete;
//Create a Lua user data pointed to this object. (-0,+1,e)
//state: Lua state.
//metatableName: Metatable name.
void createUserData(lua_State* state,const char* metatableName){
//Convert this object to T.
//NOTE: we omit the runtime safety check, only leave the compile time check (by static_cast).
T* obj=static_cast<T*>(this);
//Create user data.
ScriptUserData* ud=(ScriptUserData*)lua_newuserdata(state,sizeof(ScriptUserData));
ud->sig1=sig1;
ud->sig2=sig2;
ud->sig3=sig3;
ud->sig4=sig4;
ud->data=obj;
//Add it to the linked list.
ud->next=scriptUserDataHead;
ud->prev=NULL;
if(scriptUserDataHead) scriptUserDataHead->prev=ud;
scriptUserDataHead=ud;
//Set matatable and we are done.
luaL_getmetatable(state,metatableName);
lua_setmetatable(state,-2);
#if defined(DISABLED_DEBUG_STUFF)
scriptUserClassDebugCreate(sig1,sig2,sig3,sig4,this,ud);
#endif
}
//Destroys all Lua user data associated to this object.
void destroyUserData(){
while(scriptUserDataHead){
#if defined(DISABLED_DEBUG_STUFF)
scriptUserClassDebugInvalidate(sig1,sig2,sig3,sig4,this,scriptUserDataHead);
#endif
scriptUserDataHead->data=NULL;
scriptUserDataHead=scriptUserDataHead->next;
}
}
//Convert a Lua user data in Lua stack to object. (-0,+0,e)
//state: Lua state.
//idx: Index.
//Returns: The object. NULL if this user data is invalid.
//NOTE: This data should be a user data.
static T* getObjectFromUserData(lua_State* state,int idx){
ScriptUserData* ud=(ScriptUserData*)lua_touserdata(state,idx);
if(ud && ud->sig1==sig1 && ud->sig2==sig2 && ud->sig3==sig3 && ud->sig4==sig4)
return reinterpret_cast<T*>(ud->data);
return NULL;
}
//Register __gc, __eq to given table. (-0,+0,e)
//state: Lua state.
//idx: Index.
static void registerMetatableFunctions(lua_State *state,int idx){
lua_pushstring(state,"__gc");
lua_pushcfunction(state,&garbageCollectorFunction);
lua_rawset(state,idx);
lua_pushstring(state,"__eq");
lua_pushcfunction(state,&checkEqualFunction);
lua_rawset(state,idx);
}
virtual ~ScriptUserClass(){
destroyUserData();
}
private:
ScriptUserData* scriptUserDataHead;
//The garbage collector (__gc) function.
static int garbageCollectorFunction(lua_State* state){
//Check if it's a user data. It can be a table (the library itself)
if(!lua_isuserdata(state,1)) return 0;
ScriptUserData* ud=(ScriptUserData*)lua_touserdata(state,1);
if(ud){
if(ud->data){
//It should be impossible unless there is a bug in code
assert(ud->sig1==sig1 && ud->sig2==sig2 && ud->sig3==sig3 && ud->sig4==sig4);
//Unlink it
if(ud->next) ud->next->prev=ud->prev;
if(ud->prev) ud->prev->next=ud->next;
else{
ScriptUserClass* owner=static_cast<ScriptUserClass*>(reinterpret_cast<T*>(ud->data));
owner->scriptUserDataHead=ud->next;
}
#if defined(DISABLED_DEBUG_STUFF)
scriptUserClassDebugUnlink(sig1,sig2,sig3,sig4,
static_cast<ScriptUserClass*>(reinterpret_cast<T*>(ud->data)),ud);
#endif
}
ud->data=NULL;
ud->next=NULL;
ud->prev=NULL;
}
return 0;
}
//The 'operator==' (__eq) function.
static int checkEqualFunction(lua_State* state){
//Check if it's a user data. It can be a table (the library itself)
if(!lua_isuserdata(state,1) || !lua_isuserdata(state,2)) return 0;
ScriptUserData* ud1=(ScriptUserData*)lua_touserdata(state,1);
ScriptUserData* ud2=(ScriptUserData*)lua_touserdata(state,2);
if(ud1!=NULL && ud2!=NULL){
//It should be impossible unless there is a bug in code
assert(ud1->sig1==sig1 && ud1->sig2==sig2 && ud1->sig3==sig3 && ud1->sig4==sig4);
assert(ud2->sig1==sig1 && ud2->sig2==sig2 && ud2->sig3==sig3 && ud2->sig4==sig4);
lua_pushboolean(state,ud1->data==ud2->data);
return 1;
}
return 0;
}
};
//Another helper class to bind C++ class to Lua user data.
//This allows dynamic changes of the pointer which pointing to the actual C++ class.
//Typical use case is a class which can dynamically create/delete during game running and has save/load feature.
template<char sig1, char sig2, char sig3, char sig4, class T>
class ScriptProxyUserClass {
public:
//The default constructor, which creates a new proxy object.
ScriptProxyUserClass() : proxy(new Proxy()) {
}
//The copy constructor, which reuses proxy object from existing one.
//NOTE: You must call this function in your copy constructor!!!
ScriptProxyUserClass(const ScriptProxyUserClass& other) : proxy(other.proxy) {
}
ScriptProxyUserClass& operator=(const ScriptProxyUserClass& other) = delete;
virtual ~ScriptProxyUserClass() {
if (proxy->object == static_cast<T*>(this)) {
proxy->object = NULL;
}
}
//Set current object as active object, i.e. accessible from Lua.
//Usually called when the object is created at the first time, or when the game is loaded.
void setActive() {
proxy->object = static_cast<T*>(this);
}
//Create a Lua user data pointed to this object. (-0,+1,e)
//state: Lua state.
//metatableName: Metatable name.
void createUserData(lua_State* state, const char* metatableName) {
assert(proxy->object == static_cast<T*>(this));
proxy->createUserData(state, metatableName);
}
//Convert a Lua user data in Lua stack to object. (-0,+0,e)
//state: Lua state.
//idx: Index.
//Returns: The object. NULL if this user data is invalid.
//NOTE: This data should be a user data.
static T* getObjectFromUserData(lua_State* state, int idx) {
Proxy *p = Proxy::getObjectFromUserData(state, idx);
if (p == NULL) return NULL;
return p->object;
}
//Register __gc, __eq to given table. (-0,+0,e)
//state: Lua state.
//idx: Index.
static void registerMetatableFunctions(lua_State *state, int idx) {
Proxy::registerMetatableFunctions(state, idx);
}
private:
class Proxy : public ScriptUserClass<sig1, sig2, sig3, sig4, Proxy> {
friend class ScriptProxyUserClass;
public:
Proxy() : object(NULL) {
}
virtual ~Proxy() {
}
private:
T *object;
};
std::shared_ptr<Proxy> proxy;
};
#endif

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