2 /// Expose C++ objects to Nasal as ghosts
4 // Copyright (C) 2012 Thomas Geymayer <tomgey@gmail.com>
6 // This library is free software; you can redistribute it and/or
7 // modify it under the terms of the GNU Library General Public
8 // License as published by the Free Software Foundation; either
9 // version 2 of the License, or (at your option) any later version.
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 // Library General Public License for more details.
16 // You should have received a copy of the GNU Library General Public
17 // License along with this library; if not, write to the Free Software
18 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
20 #ifndef SG_NASAL_GHOST_HXX_
21 #define SG_NASAL_GHOST_HXX_
23 #include "NasalCallContext.hxx"
24 #include "NasalObjectHolder.hxx"
26 #include <simgear/debug/logstream.hxx>
27 #include <simgear/structure/SGWeakReferenced.hxx>
28 #include <simgear/structure/SGWeakPtr.hxx>
30 #include <boost/bind.hpp>
31 #include <boost/call_traits.hpp>
32 #include <boost/function.hpp>
33 #include <boost/lambda/lambda.hpp>
34 #include <boost/mpl/has_xxx.hpp>
35 #include <boost/preprocessor/iteration/iterate.hpp>
36 #include <boost/shared_ptr.hpp>
37 #include <boost/utility/enable_if.hpp>
42 inline T* get_pointer(boost::weak_ptr<T> const& p)
44 return p.lock().get();
48 inline T* get_pointer(SGWeakPtr<T> const& p)
50 return p.lock().get();
54 * Bindings between C++ and the Nasal scripting language
62 * Metadata for Ghost object types
68 * Add a nasal base class to the ghost. Will be available in the ghosts
71 void addNasalBase(const naRef& parent)
73 assert( naIsHash(parent) );
74 _parents.push_back(parent);
77 bool isBaseOf(naGhostType* ghost_type) const
79 if( ghost_type == _ghost_type_ptr )
82 for( DerivedList::const_iterator derived = _derived_classes.begin();
83 derived != _derived_classes.end();
86 if( (*derived)->isBaseOf(ghost_type) )
95 typedef std::vector<const GhostMetadata*> DerivedList;
97 const std::string _name;
98 const naGhostType *_ghost_type_ptr;
99 DerivedList _derived_classes;
100 std::vector<naRef> _parents;
102 GhostMetadata( const std::string& name,
103 const naGhostType* ghost_type ):
105 _ghost_type_ptr(ghost_type)
110 void addDerived(const GhostMetadata* derived)
113 _derived_classes.push_back(derived);
119 "Ghost::addDerived: " << _name << " -> " << derived->_name
123 naRef getParents(naContext c)
125 return nasal::to_nasal(c, _parents);
130 * Hold callable method and convert to Nasal function if required.
133 public SGWeakReferenced
136 virtual ~MethodHolder() {}
138 naRef get_naRef(naContext c)
141 _obj.reset(createNasalObject(c));
142 return _obj.get_naRef();
148 virtual naRef createNasalObject(naContext c) = 0;
151 BOOST_MPL_HAS_XXX_TRAIT_DEF(element_type)
156 typedef typename boost::remove_cv<
157 typename boost::remove_reference<T>::type
161 template<class T1, class T2>
162 struct reduced_is_same:
163 public boost::is_same<typename reduced_type<T1>::type, T2>
167 typedef SGSharedPtr<internal::MethodHolder> MethodHolderPtr;
168 typedef SGWeakPtr<internal::MethodHolder> MethodHolderWeakPtr;
171 * Class for exposing C++ objects to Nasal
174 * // Example class to be exposed to Nasal
182 * void doSomethingElse(const nasal::CallContext& ctx);
184 * typedef boost::shared_ptr<MyClass> MyClassPtr;
186 * std::string myOtherFreeMember(int num);
188 * void exposeClasses()
190 * // Register a nasal ghost type for MyClass. This needs to be done only
191 * // once before creating the first ghost instance. The exposed class needs
192 * // to be wrapped inside a shared pointer, eg. boost::shared_ptr.
193 * Ghost<MyClassPtr>::init("MyClass")
194 * // Members can be exposed by getters and setters
195 * .member("x", &MyClass::getX, &MyClass::setX)
196 * // For readonly variables only pass a getter
197 * .member("x_readonly", &MyClass::getX)
198 * // It is also possible to expose writeonly members
199 * .member("x_writeonly", &MyClass::setX)
200 * // Methods can be nearly anything callable and accepting a reference
201 * // to an instance of the class type. (member functions, free functions
202 * // and anything else bindable using boost::function and boost::bind)
203 * .method("myMember", &MyClass::myMember)
204 * .method("doSomething", &MyClass::doSomethingElse)
205 * .method("other", &myOtherFreeMember);
211 public internal::GhostMetadata
213 BOOST_STATIC_ASSERT( internal::has_element_type<T>::value );
216 typedef typename T::element_type raw_type;
218 typedef naRef (raw_type::*member_func_t)(const CallContext&);
219 typedef naRef (*free_func_t)(raw_type&, const CallContext&);
220 typedef boost::function<naRef(naContext, raw_type&)> getter_t;
221 typedef boost::function<void(naContext, raw_type&, naRef)> setter_t;
222 typedef boost::function<naRef(raw_type&, const CallContext&)> method_t;
223 typedef boost::function<bool( naContext,
226 naRef )> fallback_setter_t;
229 public internal::MethodHolder
232 explicit MethodHolder(const method_t& method):
238 typedef SGSharedPtr<MethodHolder> SharedPtr;
239 typedef SGWeakPtr<MethodHolder> WeakPtr;
243 virtual naRef createNasalObject(naContext c)
255 static void destroyHolder(void* user_data)
257 delete static_cast<WeakPtr*>(user_data);
260 static naRef call( naContext c,
266 WeakPtr* holder_weak = static_cast<WeakPtr*>(user_data);
268 naRuntimeError(c, "invalid method holder!");
272 SharedPtr holder = holder_weak->lock();
274 throw std::runtime_error("holder has expired");
276 return holder->_method
278 requireObject(c, me),
279 CallContext(c, argc, args)
282 catch(const std::exception& ex)
284 naRuntimeError(c, "Fatal error in method call: %s", ex.what());
288 naRuntimeError(c, "Unknown exception in method call.");
296 * A ghost member. Can consist either of getter and/or setter functions
297 * for exposing a data variable or a single callable function.
304 member_t( const getter_t& getter,
305 const setter_t& setter,
306 const MethodHolderPtr& func = MethodHolderPtr() ):
312 explicit member_t(const MethodHolderPtr& func):
318 MethodHolderPtr func;
321 typedef std::map<std::string, member_t> MemberMap;
324 * Register a new ghost type.
326 * @note Only intialize each ghost type once!
328 * @param name Descriptive name of the ghost type.
330 static Ghost& init(const std::string& name)
332 getSingletonHolder().reset( new Ghost(name) );
333 return *getSingletonPtr();
337 * Check whether ghost type has already been initialized.
341 return getSingletonPtr();
345 * Register a base class for this ghost. The base class needs to be
346 * registers on its own before it can be used as base class.
348 * @tparam BaseGhost Type of base class already wrapped into Ghost class
352 * Ghost<MyBasePtr>::init("MyBase");
353 * Ghost<MyClassPtr>::init("MyClass")
354 * .bases<Ghost<MyBasePtr> >();
357 template<class BaseGhost>
358 typename boost::enable_if
360 boost::is_base_of<GhostMetadata, BaseGhost>,
367 boost::is_base_of<typename BaseGhost::raw_type, raw_type>::value
370 BaseGhost* base = BaseGhost::getSingletonPtr();
374 // Both ways of retrieving the address of a static member function
375 // should be legal but not all compilers know this.
376 // g++-4.4.7+ has been tested to work with both versions
377 #if defined(SG_GCC_VERSION) && SG_GCC_VERSION < 40407
378 // The old version of g++ used on Jenkins (16.11.2012) only compiles
380 &getTypeFor<BaseGhost>
382 // VS (2008, 2010, ... ?) only allow this version.
383 &Ghost::getTypeFor<BaseGhost>
387 // Replace any getter that is not available in the current class.
388 // TODO check if this is the correct behavior of function overriding
389 for( typename BaseGhost::MemberMap::const_iterator member =
390 base->_members.begin();
391 member != base->_members.end();
394 if( _members.find(member->first) == _members.end() )
395 _members[member->first] = member_t
397 member->second.getter,
398 member->second.setter,
403 if( !_fallback_setter )
404 _fallback_setter = base->_fallback_setter;
410 * Register a base class for this ghost. The base class needs to be
411 * registers on its own before it can be used as base class.
413 * @tparam Base Type of base class (Base as used in Ghost<BasePtr>)
416 * Ghost<MyBasePtr>::init("MyBase");
417 * Ghost<MyClassPtr>::init("MyClass")
418 * .bases<MyBasePtr>();
422 typename boost::disable_if
424 boost::is_base_of<GhostMetadata, Base>,
431 boost::is_base_of<typename Ghost<Base>::raw_type, raw_type>::value
434 return bases< Ghost<Base> >();
438 * Register an existing Nasal class/hash as base class for this ghost.
440 * @param parent Nasal hash/class
442 Ghost& bases(const naRef& parent)
444 addNasalBase(parent);
449 * Register a member variable by passing a getter and/or setter method.
451 * @param field Name of member
452 * @param getter Getter for variable
453 * @param setter Setter for variable (Pass 0 to prevent write access)
456 template<class Ret, class Param>
457 Ghost& member( const std::string& field,
458 Ret (raw_type::*getter)() const,
459 void (raw_type::*setter)(Param) )
461 return member(field, to_getter(getter), to_setter(setter));
465 * Register a read only member variable.
467 * @param field Name of member
468 * @param getter Getter for variable
471 Ghost& member( const std::string& field,
472 Ret (raw_type::*getter)() const )
474 return member(field, to_getter(getter), setter_t());
478 * Register a write only member variable.
480 * @param field Name of member
481 * @param setter Setter for variable
484 Ghost& member( const std::string& field,
485 void (raw_type::*setter)(Var) )
487 return member(field, getter_t(), to_setter(setter));
491 * Register a member variable by passing a getter and/or setter method.
493 * @param field Name of member
494 * @param getter Getter for variable
495 * @param setter Setter for variable (Pass empty to prevent write access)
498 Ghost& member( const std::string& field,
499 const getter_t& getter,
500 const setter_t& setter = setter_t() )
502 if( !getter.empty() || !setter.empty() )
503 _members[field] = member_t(getter, setter);
509 "Member '" << field << "' requires a getter or setter"
515 * Register a function which is called upon setting an unknown member of
518 Ghost& _set(const fallback_setter_t& setter)
520 _fallback_setter = setter;
525 * Register a method which is called upon setting an unknown member of
532 * bool setMember( const std::string& key,
533 * const std::string& value );
536 * Ghost<MyClassPtr>::init("Test")
537 * ._set(&MyClass::setMember);
540 template<class Param>
541 Ghost _set(bool (raw_type::*setter)(const std::string&, Param))
543 // Setter signature: bool( naContext,
545 // const std::string&,
547 return _set(boost::bind(
551 boost::bind(from_nasal_ptr<Param>::get(), _1, _4)
556 * Register anything that accepts an object instance and a
557 * nasal::CallContext and returns naRef as method.
563 * naRef myMethod(const nasal::CallContext& ctx);
566 * Ghost<MyClassPtr>::init("Test")
567 * .method("myMethod", &MyClass::myMethod);
570 Ghost& method(const std::string& name, const method_t& func)
572 _members[name].func = new MethodHolder(func);
577 * Register anything that accepts an object instance and a
578 * nasal::CallContext whith automatic conversion of the return type to
583 * void doIt(const MyClass& c, const nasal::CallContext& ctx);
585 * Ghost<MyClassPtr>::init("Test")
586 * .method("doIt", &doIt);
592 const std::string& name,
593 const boost::function<Ret (raw_type&, const CallContext&)>& func
596 return method(name, boost::bind(method_invoker<Ret>, func, _1, _2));
599 // Build dependency for CMake, gcc, etc.
600 #define SG_DONT_DO_ANYTHING
601 # include <simgear/nasal/cppbind/detail/functor_templates.hxx>
602 #undef SG_DONT_DO_ANYTHING
604 #define BOOST_PP_ITERATION_LIMITS (0, 9)
605 #define BOOST_PP_FILENAME_1 <simgear/nasal/cppbind/detail/functor_templates.hxx>
606 #include BOOST_PP_ITERATE()
608 // TODO use variadic template when supporting C++11
609 // TODO check if default constructor exists
610 // static naRef create( naContext c )
612 // return makeGhost(c, createInstance());
616 * Create a Nasal instance of this ghost.
618 * @param c Active Nasal context
619 * @param a1 Parameter used for creating new instance
622 static naRef create( naContext c, const A1& a1 )
624 return makeGhost(c, createInstance(a1));
628 * Nasal callback for creating a new instance of this ghost.
630 static naRef f_create(naContext c, naRef me, int argc, naRef* args)
635 static bool isBaseOf(naGhostType* ghost_type)
640 return getSingletonPtr()->GhostMetadata::isBaseOf(ghost_type);
643 static bool isBaseOf(naRef obj)
645 return isBaseOf( naGhost_type(obj) );
649 * Convert Nasal object to C++ object. To get a valid object the passed
650 * Nasal objects has to be derived class of the target class (Either
651 * derived in C++ or in Nasal using a 'parents' vector)
653 static pointer fromNasal(naContext c, naRef me)
655 // Check if it's a ghost and if it can be converted
656 if( isBaseOf( naGhost_type(me) ) )
657 return getPtr( naGhost_ptr(me) );
659 // Now if it is derived from a ghost (hash with ghost in parent vector)
660 else if( naIsHash(me) )
662 naRef na_parents = naHash_cget(me, const_cast<char*>("parents"));
663 if( !naIsVector(na_parents) )
666 typedef std::vector<naRef> naRefs;
667 naRefs parents = from_nasal<naRefs>(c, na_parents);
668 for( naRefs::const_iterator parent = parents.begin();
669 parent != parents.end();
672 pointer ptr = fromNasal(c, *parent);
673 if( get_pointer(ptr) )
686 static naGhostType _ghost_type;
688 typedef naGhostType* (*type_checker_t)(const raw_type*);
689 typedef std::vector<type_checker_t> DerivedList;
690 DerivedList _derived_types;
693 * Create a shared pointer on the heap to handle the reference counting
694 * for the passed shared pointer while it is used in Nasal space.
696 static pointer* createInstance(const pointer& ptr)
698 return get_pointer(ptr) ? new pointer(ptr) : 0;
701 static pointer getPtr(void* ptr)
704 return *static_cast<pointer*>(ptr);
709 static raw_type* getRawPtr(void* ptr)
712 return get_pointer(*static_cast<pointer*>(ptr));
717 static raw_type* getRawPtr(const pointer& ptr)
719 return get_pointer(ptr);
722 void addDerived( const internal::GhostMetadata* derived_meta,
723 const type_checker_t& derived_info )
725 GhostMetadata::addDerived(derived_meta);
726 _derived_types.push_back(derived_info);
729 template<class BaseGhost>
731 typename boost::enable_if
732 < boost::is_polymorphic<typename BaseGhost::raw_type>,
735 getTypeFor(const typename BaseGhost::raw_type* base)
737 // Check first if passed pointer can by converted to instance of class
740 < typename BaseGhost::raw_type,
741 typename Ghost::raw_type
743 && dynamic_cast<const typename Ghost::raw_type*>(base) != base )
746 if( !getSingletonPtr() )
752 "Ghost::getTypeFor: can not get type for unregistered ghost"
757 // Now check if we can further downcast to one of our derived classes.
758 for( typename DerivedList::reverse_iterator
759 derived = getSingletonPtr()->_derived_types.rbegin();
760 derived != getSingletonPtr()->_derived_types.rend();
763 naGhostType* ghost_type =
764 (*derived)( static_cast<const typename Ghost::raw_type*>(base) );
769 // If base is not an instance of any derived class, this class has to
770 // be the dynamic type.
774 template<class BaseGhost>
776 typename boost::disable_if
777 < boost::is_polymorphic<typename BaseGhost::raw_type>,
780 getTypeFor(const typename BaseGhost::raw_type* base)
782 // For non polymorphic classes there is no possibility to get the actual
783 // dynamic type, therefore we can only use its static type.
784 return &BaseGhost::_ghost_type;
787 static Ghost* getSingletonPtr()
789 return getSingletonHolder().get();
792 static raw_type& requireObject(naContext c, naRef me)
794 raw_type* obj = getRawPtr( fromNasal(c, me) );
795 naGhostType* ghost_type = naGhost_type(me);
801 "method called on object of wrong type: is '%s' expected '%s'",
802 naIsNil(me) ? "nil" : (ghost_type ? ghost_type->name : "unknown"),
810 getter_t to_getter(Ret (raw_type::*getter)() const)
812 typedef typename boost::call_traits<Ret>::param_type param_type;
813 naRef(*to_nasal_)(naContext, param_type) = &to_nasal;
815 // Getter signature: naRef(naContext, raw_type&)
820 boost::bind(getter, _2)
824 template<class Param>
825 setter_t to_setter(void (raw_type::*setter)(Param))
827 // Setter signature: void(naContext, raw_type&, naRef)
832 boost::bind(from_nasal_ptr<Param>::get(), _1, _3)
838 * Invoke a method which returns a value and convert it to Nasal.
842 typename boost::disable_if<boost::is_void<Ret>, naRef>::type
845 const boost::function<Ret (raw_type&, const CallContext&)>& func,
847 const CallContext& ctx
850 return (*to_nasal_ptr<Ret>::get())(ctx.c, func(obj, ctx));
854 * Invoke a method which returns void and "convert" it to nil.
858 typename boost::enable_if<boost::is_void<Ret>, naRef>::type
861 const boost::function<Ret (raw_type&, const CallContext&)>& func,
863 const CallContext& ctx
871 * Extract argument by index from nasal::CallContext and convert to given
876 typename boost::disable_if<
877 internal::reduced_is_same<Arg, CallContext>,
878 typename from_nasal_ptr<Arg>::return_type
880 arg_from_nasal(const CallContext& ctx, size_t index)
882 return ctx.requireArg<Arg>(index);
886 * Specialization to pass through nasal::CallContext.
890 typename boost::enable_if<
891 internal::reduced_is_same<Arg, CallContext>,
892 typename from_nasal_ptr<Arg>::return_type
894 arg_from_nasal(const CallContext& ctx, size_t)
896 // Either const CallContext& or CallContext, non-const reference
897 // does not make sense.
898 BOOST_STATIC_ASSERT( (!boost::is_same<Arg, CallContext&>::value) );
902 typedef std::auto_ptr<Ghost> GhostPtr;
904 fallback_setter_t _fallback_setter;
906 explicit Ghost(const std::string& name):
907 GhostMetadata(name, &_ghost_type)
909 _ghost_type.destroy = &destroyGhost;
910 _ghost_type.name = _name.c_str();
911 _ghost_type.get_member = &getMember;
912 _ghost_type.set_member = &setMember;
915 static GhostPtr& getSingletonHolder()
917 static GhostPtr instance;
921 static naRef makeGhost(naContext c, void *ptr)
925 // We are wrapping shared pointers to already existing objects which
926 // will then be hold be a new shared pointer. We therefore have to
927 // check for the dynamic type of the object as it might differ from
928 // the passed static type.
929 naGhostType* ghost_type = getTypeFor<Ghost>( getRawPtr(ptr) );
932 return naNewGhost2(c, ghost_type, ptr);
939 static void destroyGhost(void *ptr)
941 delete static_cast<pointer*>(ptr);
945 * Callback for retrieving a ghost member.
947 static const char* getMember(naContext c, void* g, naRef key, naRef* out)
949 const std::string key_str = nasal::from_nasal<std::string>(c, key);
950 // TODO merge instance parents with static class parents
951 // if( key_str == "parents" )
953 // if( getSingletonPtr()->_parents.empty() )
956 // *out = getSingletonPtr()->getParents(c);
960 typename MemberMap::iterator member =
961 getSingletonPtr()->_members.find(key_str);
963 if( member == getSingletonPtr()->_members.end() )
966 if( member->second.func )
967 *out = member->second.func->get_naRef(c);
968 else if( !member->second.getter.empty() )
969 *out = member->second.getter(c, *getRawPtr(g));
971 return "Read-protected member";
977 * Callback for writing to a ghost member.
979 static void setMember(naContext c, void* g, naRef field, naRef val)
981 const std::string key = nasal::from_nasal<std::string>(c, field);
982 const MemberMap& members = getSingletonPtr()->_members;
984 typename MemberMap::const_iterator member = members.find(key);
985 if( member == members.end() )
987 fallback_setter_t fallback_set = getSingletonPtr()->_fallback_setter;
989 naRuntimeError(c, "ghost: No such member: %s", key.c_str());
990 else if( !fallback_set(c, *getRawPtr(g), key, val) )
991 naRuntimeError(c, "ghost: Failed to write (_set: %s)", key.c_str());
993 else if( member->second.setter.empty() )
994 naRuntimeError(c, "ghost: Write protected member: %s", key.c_str());
995 else if( member->second.func )
996 naRuntimeError(c, "ghost: Write to function: %s", key.c_str());
998 member->second.setter(c, *getRawPtr(g), val);
1003 naGhostType Ghost<T>::_ghost_type;
1005 } // namespace nasal
1007 // Needs to be outside any namespace to make ADL work
1009 * Convert every shared pointer to a ghost.
1012 typename boost::enable_if<
1013 nasal::internal::has_element_type<
1014 typename nasal::internal::reduced_type<T>::type
1018 to_nasal_helper(naContext c, T ptr)
1020 return nasal::Ghost<T>::create(c, ptr);
1024 * Convert nasal ghosts/hashes to shared pointer (of a ghost).
1027 typename boost::enable_if<
1028 nasal::internal::has_element_type<
1029 typename nasal::internal::reduced_type<T>::type
1033 from_nasal_helper(naContext c, naRef ref, const T*)
1035 return nasal::Ghost<T>::fromNasal(c, ref);
1039 * Convert any pointer to a SGReference based object to a ghost.
1042 typename boost::enable_if<boost::is_base_of<SGReferenced, T>, naRef>::type
1043 to_nasal_helper(naContext c, T* ptr)
1045 return nasal::Ghost<SGSharedPtr<T> >::create(c, SGSharedPtr<T>(ptr));
1049 * Convert nasal ghosts/hashes to pointer (of a SGReference based ghost).
1052 typename boost::enable_if<
1053 boost::is_base_of<SGReferenced, typename boost::remove_pointer<T>::type>,
1056 from_nasal_helper(naContext c, naRef ref, const T*)
1058 typedef SGSharedPtr<typename boost::remove_pointer<T>::type> TypeRef;
1059 return nasal::Ghost<TypeRef>::fromNasal(c, ref).release();
1062 #endif /* SG_NASAL_GHOST_HXX_ */