Functor.h

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/*
 *   ORXONOX - the hottest 3D action shooter ever to exist
 *                    > www.orxonox.net <
 *
 *
 *   License notice:
 *
 *   This program 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 2
 *   of the License, or (at your option) any later version.
 *
 *   This program 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 this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 *   Author:
 *      Fabian 'x3n' Landau
 *   Co-authors:
 *      ...
 *
 */

#ifndef _Functor_H__
#define _Functor_H__

#include "core/CorePrereqs.h"

#include <typeinfo>

#include "util/Output.h"
#include "util/MultiType.h"
#include "core/object/Destroyable.h"
#include "FunctorPtr.h"

namespace orxonox
{
    const unsigned int MAX_FUNCTOR_ARGUMENTS = 5;   

    namespace detail
    {
        template <class T>
        inline std::string _typeToString() { return "unknown"; }

        template <> inline std::string _typeToString<void>()               { return "void"; }
        template <> inline std::string _typeToString<int>()                { return "int"; }
        template <> inline std::string _typeToString<unsigned int>()       { return "uint"; }
        template <> inline std::string _typeToString<char>()               { return "char"; }
        template <> inline std::string _typeToString<unsigned char>()      { return "uchar"; }
        template <> inline std::string _typeToString<short>()              { return "short"; }
        template <> inline std::string _typeToString<unsigned short>()     { return "ushort"; }
        template <> inline std::string _typeToString<long>()               { return "long"; }
        template <> inline std::string _typeToString<unsigned long>()      { return "ulong"; }
        template <> inline std::string _typeToString<long long>()          { return "longlong"; }
        template <> inline std::string _typeToString<unsigned long long>() { return "ulonglong"; }
        template <> inline std::string _typeToString<float>()              { return "float"; }
        template <> inline std::string _typeToString<double>()             { return "double"; }
        template <> inline std::string _typeToString<long double>()        { return "longdouble"; }
        template <> inline std::string _typeToString<bool>()               { return "bool"; }
        template <> inline std::string _typeToString<std::string>()        { return "string"; }
        template <> inline std::string _typeToString<Vector2>()            { return "Vector2"; }
        template <> inline std::string _typeToString<Vector3>()            { return "Vector3"; }
        template <> inline std::string _typeToString<Quaternion>()         { return "Quaternion"; }
        template <> inline std::string _typeToString<ColourValue>()        { return "ColourValue"; }
        template <> inline std::string _typeToString<Radian>()             { return "Radian"; }
        template <> inline std::string _typeToString<Degree>()             { return "Degree"; }
    }

    template <class T>
    inline std::string typeToString() { return detail::_typeToString<typename Loki::TypeTraits<T>::UnqualifiedReferredType>(); }

    class _CoreExport Functor
    {
        public:
            enum class Type
            {
                Static,
                Member
            };

        public:
            virtual ~Functor() = default;

            virtual MultiType operator()(const MultiType& param1 = MultiType::Null, const MultiType& param2 = MultiType::Null, const MultiType& param3 = MultiType::Null, const MultiType& param4 = MultiType::Null, const MultiType& param5 = MultiType::Null) = 0;

            virtual FunctorPtr clone() = 0;

            virtual Type getType() const = 0;
            virtual unsigned int getParamCount() const = 0;
            virtual bool hasReturnvalue() const = 0;

            virtual std::string getTypenameParam(unsigned int index) const = 0;
            virtual std::string getTypenameReturnvalue() const = 0;

            virtual void evaluateArgument(unsigned int index, MultiType& argument) const = 0;

            virtual void setRawObjectPointer(void* object) = 0;
            virtual void* getRawObjectPointer() const = 0;

            virtual void setSafeMode(bool bSafeMode) = 0;

            virtual const std::type_info& getFullIdentifier() const = 0;
            virtual const std::type_info& getHeaderIdentifier() const = 0;
            virtual const std::type_info& getHeaderIdentifier(unsigned int params) const = 0;
    };

    template <class O>
    class FunctorMember : public Functor, public DestructionListener
    {
        public:
            FunctorMember(O* object = nullptr) : object_(object), bSafeMode_(false) {}
            virtual ~FunctorMember() { if (this->bSafeMode_) { this->unregisterObject(this->object_); } }

            virtual MultiType operator()(O* object, const MultiType& param1 = MultiType::Null, const MultiType& param2 = MultiType::Null, const MultiType& param3 = MultiType::Null, const MultiType& param4 = MultiType::Null, const MultiType& param5 = MultiType::Null) = 0;

            // see Functor::operator()()
            virtual MultiType operator()(const MultiType& param1 = MultiType::Null, const MultiType& param2 = MultiType::Null, const MultiType& param3 = MultiType::Null, const MultiType& param4 = MultiType::Null, const MultiType& param5 = MultiType::Null) override
            {
                // call the function if an object was assigned
                if (this->object_)
                    return (*this)(this->object_, param1, param2, param3, param4, param5);
                else
                {
                    orxout(internal_error) << "Can't execute FunctorMember, no object set." << endl;
                    return MultiType::Null;
                }
            }

            // see Functor::getType()
            virtual inline Functor::Type getType() const override
                { return Functor::Type::Member; }

            inline void setObject(O* object)
            {
                if (this->bSafeMode_ && object != this->object_)
                {
                    this->unregisterObject(this->object_);
                    this->registerObject(object);
                }
                this->object_ = object;
            }
            inline O* getObject() const
                { return this->object_; }

            // see Functor::setRawObjectPointer()
            virtual inline void setRawObjectPointer(void* object) override
                { this->setObject((O*)object); }
            // see Functor::getRawObjectPointer()
            virtual inline void* getRawObjectPointer() const override
                { return this->object_; }

            // see Functor::setSafeMode()
            virtual inline void setSafeMode(bool bSafeMode) override
            {
                if (bSafeMode == this->bSafeMode_)
                    return;

                this->bSafeMode_ = bSafeMode;

                if (bSafeMode)
                    this->registerObject(this->object_);
                else
                    this->unregisterObject(this->object_);
            }

        protected:
            inline void registerObject(Destroyable* object)
                { this->registerAsDestructionListener(object); }

            inline void registerObject(void* object) {}

            inline void unregisterObject(Destroyable* object)
                { this->unregisterAsDestructionListener(object); }

            inline void unregisterObject(void* object) {}

            virtual inline void objectDeleted() override
                { this->object_ = nullptr; }

            O* object_;     
            bool bSafeMode_; 
    };

    template <>
    class FunctorMember<void> : public Functor
    {
        public:
            FunctorMember(void* object = nullptr) {}

            virtual MultiType operator()(void* object, const MultiType& param1 = MultiType::Null, const MultiType& param2 = MultiType::Null, const MultiType& param3 = MultiType::Null, const MultiType& param4 = MultiType::Null, const MultiType& param5 = MultiType::Null) = 0;

            // see Functor::operator()()
            virtual MultiType operator()(const MultiType& param1 = MultiType::Null, const MultiType& param2 = MultiType::Null, const MultiType& param3 = MultiType::Null, const MultiType& param4 = MultiType::Null, const MultiType& param5 = MultiType::Null) override
            {
                return (*this)((void*)nullptr, param1, param2, param3, param4, param5);
            }

            // see Functor::getType()
            virtual inline Functor::Type getType() const override
                { return Functor::Type::Static; }

            // see Functor::setRawObjectPointer()
            virtual inline void setRawObjectPointer(void*) override
                { orxout(internal_warning) << "Can't assign an object pointer to a static functor" << endl; }
            // see Functor::getRawObjectPointer()
            virtual inline void* getRawObjectPointer() const override
                { return nullptr; }

            // see Functor::setSafeMode()
            virtual inline void setSafeMode(bool) override {}
    };

    typedef FunctorMember<void> FunctorStatic;

    template <class F, class O = void>
    class FunctorPointer : public FunctorMember<O>
    {
        public:
            FunctorPointer(F functionPointer, O* object = nullptr) : FunctorMember<O>(object), functionPointer_(functionPointer) {}

            inline void setFunction(F functionPointer)
                { this->functionPointer_ = functionPointer; }
            inline F getFunction() const
                { return this->functionPointer_; }

        protected:
            F functionPointer_;     
    };

    namespace detail
    {
        // Helper class to get the type of the function-pointer (or the function-object) with the given class, parameters, return-value, and constness
        template <class F, class R, class O, bool isconst, class... Params> struct FunctionType /* generic type is undefined */;
        template <         class R, class O,               class... Params> struct FunctionType<void, R, O,    false, Params...> { typedef R (O::*Type)(Params...); };       // spezialization: non-const member function
        template <         class R, class O,               class... Params> struct FunctionType<void, R, O,    true,  Params...> { typedef R (O::*Type)(Params...) const; }; // spezialization: const member function
        template <         class R,                        class... Params> struct FunctionType<void, R, void, false, Params...> { typedef R (*Type)(Params...); };          // spezialization: static function
        template <class F, class R,                        class... Params> struct FunctionType<F,    R, void, false, Params...> { typedef F Type; };                        // spezialization: function object

        // Helper class, used to call a function with a given object and parameters and to return its return-value (if available)
        template <class F, class R, class O, bool isconst, class... Params> struct FunctorCaller /* generic type is undefined */;
        template <         class R, class O, bool isconst, class... Params> struct FunctorCaller<void, R,    O,    isconst, Params...> { template <class... UnusedParams> static inline MultiType call(typename detail::FunctionType<void, R,    O,    isconst, Params...>::Type functionPointer, O* object, const Params&... parameters, const UnusedParams&...) { return (object->*functionPointer)(parameters...); } };                  // spezialization: member function with return value
        template <                  class O, bool isconst, class... Params> struct FunctorCaller<void, void, O,    isconst, Params...> { template <class... UnusedParams> static inline MultiType call(typename detail::FunctionType<void, void, O,    isconst, Params...>::Type functionPointer, O* object, const Params&... parameters, const UnusedParams&...) { (object->*functionPointer)(parameters...); return MultiType::Null; } }; // spezialization: member function without return value
        template <         class R,                        class... Params> struct FunctorCaller<void, R,    void, false,   Params...> { template <class... UnusedParams> static inline MultiType call(typename detail::FunctionType<void, R,    void, false,   Params...>::Type functionPointer, void*,     const Params&... parameters, const UnusedParams&...) { return (*functionPointer)(parameters...); } };                          // spezialization: static function with return value
        template <                                         class... Params> struct FunctorCaller<void, void, void, false,   Params...> { template <class... UnusedParams> static inline MultiType call(typename detail::FunctionType<void, void, void, false,   Params...>::Type functionPointer, void*,     const Params&... parameters, const UnusedParams&...) { (*functionPointer)(parameters...); return MultiType::Null; } };         // spezialization: static function without return value
        template <class F, class R,                        class... Params> struct FunctorCaller<F,    R,    void, false,   Params...> { template <class... UnusedParams> static inline MultiType call(typename detail::FunctionType<F,    R,    void, false,   Params...>::Type functor,         void*,     const Params&... parameters, const UnusedParams&...) { return functor(parameters...); } };                                     // spezialization: function object with return value
        template <class F,                                 class... Params> struct FunctorCaller<F,    void, void, false,   Params...> { template <class... UnusedParams> static inline MultiType call(typename detail::FunctionType<F,    void, void, false,   Params...>::Type functor,         void*,     const Params&... parameters, const UnusedParams&...) { functor(parameters...); return MultiType::Null; } };                    // spezialization: function object without return value

        // Helper class to determine if a function has a returnvalue
        template <class T>
        struct FunctorHasReturnvalue
        { enum { result = true }; };
        template <>
        struct FunctorHasReturnvalue<void>
        { enum { result = false }; };

        // Helper class to determine the N-th parameter of a variadic template (with 0 being the index of the first parameter)
        template <int n, typename T = void, typename... Other>
        struct GetNthParamType
        { typedef typename GetNthParamType<n - 1, Other...>::Type Type; };
        template <typename T, typename... Other>
        struct GetNthParamType<0, T, Other...>
        { typedef T Type; };

        // Helper structs to deduce the first N types of a parameter pack
        template<class... Types> struct type_list {};

        template <class T1, class... AllTypes>
        struct make_type_list_helper
        {
            template <std::size_t N, class... Types>
            struct make_type_list_impl : make_type_list_helper<AllTypes...>::template make_type_list_impl<N - 1, Types..., T1> {};

            template <class... Types>
            struct make_type_list_impl<1u, Types...> : type_list<Types..., T1> {};
        };

        template <class T1>
        struct make_type_list_helper<T1>
        {
            template <std::size_t N, class... Types>
            struct make_type_list_impl : type_list<Types..., T1> {};
        };

        template <std::size_t N, class... Types>
        struct make_type_list : make_type_list_helper<Types...>::template make_type_list_impl<N> {};

        template <class... Types>
        struct make_type_list<0u, Types...> : type_list<> {};

        template <std::size_t N>
        struct make_type_list<N> : type_list<> {};

        template <>
        struct make_type_list<0u> : type_list<> {};
    }

    template <class F, class R, class O, bool isconst, class... Params>
    class FunctorTemplate : public FunctorPointer<typename detail::FunctionType<F, R, O, isconst, Params...>::Type, O>
    {
        static_assert(sizeof...(Params) <= 5, "Only up to 5 parameters are supported");

        public:
            FunctorTemplate(typename detail::FunctionType<F, R, O, isconst, Params...>::Type functionPointer, O* object = nullptr) : FunctorPointer<typename detail::FunctionType<F, R, O, isconst, Params...>::Type, O>(functionPointer, object) {}

            // see FunctorMember::operator()()
            virtual MultiType operator()(O* object, const MultiType& param1 = MultiType::Null, const MultiType& param2 = MultiType::Null, const MultiType& param3 = MultiType::Null, const MultiType& param4 = MultiType::Null, const MultiType& param5 = MultiType::Null) override
            {
                return detail::FunctorCaller<F, R, O, isconst, Params...>::call(this->functionPointer_, object, param1, param2, param3, param4, param5);
            }

            // see Functor::clone()
            virtual FunctorPtr clone() override
            {
                return std::make_shared<FunctorTemplate>(*this);
            }

            // see Functor::evaluateArgument()
            virtual void evaluateArgument(unsigned int index, MultiType& argument) const override
            {
                switch (index)
                {
                    case 0: argument.convert<typename detail::GetNthParamType<0, Params...>::Type>(); break;
                    case 1: argument.convert<typename detail::GetNthParamType<1, Params...>::Type>(); break;
                    case 2: argument.convert<typename detail::GetNthParamType<2, Params...>::Type>(); break;
                    case 3: argument.convert<typename detail::GetNthParamType<3, Params...>::Type>(); break;
                    case 4: argument.convert<typename detail::GetNthParamType<4, Params...>::Type>(); break;
                }
            }

            // see Functor::getParamCount()
            virtual unsigned int getParamCount() const override
            {
                return sizeof...(Params);
            }

            // see Functor::hasReturnvalue()
            virtual bool hasReturnvalue() const override
            {
                return detail::FunctorHasReturnvalue<R>::result;
            }

            // see Functor::getTypenameParam()
            virtual std::string getTypenameParam(unsigned int index) const override
            {
                switch (index)
                {
                    case 0:  return typeToString<typename detail::GetNthParamType<0, Params...>::Type>();
                    case 1:  return typeToString<typename detail::GetNthParamType<1, Params...>::Type>();
                    case 2:  return typeToString<typename detail::GetNthParamType<2, Params...>::Type>();
                    case 3:  return typeToString<typename detail::GetNthParamType<3, Params...>::Type>();
                    case 4:  return typeToString<typename detail::GetNthParamType<4, Params...>::Type>();
                    default: return "";
                }
            }

            // see Functor::getTypenameReturnvalue()
            virtual std::string getTypenameReturnvalue() const override
            {
                return typeToString<R>();
            }

            // see Functor::getFullIdentifier()
            virtual const std::type_info& getFullIdentifier() const override
            {
                return typeid(typename detail::FunctionType<void, R, O, isconst, Params...>::Type);
            }

            // see Functor::getHeaderIdentifier()
            virtual const std::type_info& getHeaderIdentifier() const override
            {
                return typeid(typename detail::FunctionType<void, R, void, false, Params...>::Type);
            }

            // see Functor::getHeaderIdentifier(unsigned int)
            virtual const std::type_info& getHeaderIdentifier(unsigned int params) const override
            {
                switch (params)
                {
                    case 0:  return this->getTypelistIdentifier(detail::make_type_list<0, Params...>{});
                    case 1:  return this->getTypelistIdentifier(detail::make_type_list<1, Params...>{});
                    case 2:  return this->getTypelistIdentifier(detail::make_type_list<2, Params...>{});
                    case 3:  return this->getTypelistIdentifier(detail::make_type_list<3, Params...>{});
                    case 4:  return this->getTypelistIdentifier(detail::make_type_list<4, Params...>{});
                    default: return this->getTypelistIdentifier(detail::make_type_list<5, Params...>{});
                }
            }

    private:
            template<class... Types>
            const std::type_info& getTypelistIdentifier(detail::type_list<Types...>) const
            {
                return typeid(typename detail::FunctionType<void, R, void, false, Types...>::Type);
            }
    };


    namespace detail
    {
        // Helper functions to deduce types and constness of operator() and return the correct FunctorTemplate
        template <class F>
        struct CallableHelper
        {
            template <class R, class... Params> static inline FunctorStaticPtr create(const F& functionObject, R(F::*)(Params...))       { return std::make_shared<FunctorTemplate<F, R, void, false, Params...>>(functionObject); }
            template <class R, class... Params> static inline FunctorStaticPtr create(const F& functionObject, R(F::*)(Params...) const) { return std::make_shared<FunctorTemplate<F, R, void, false, Params...>>(functionObject); } // note: both const and non-const function-objects are treated as static functors with isconst=false.
        };
    }

    template <class R, class O, class OO, class... Params> inline FunctorMemberPtr<O> createFunctor(R (O::*functionPointer)(Params...),       OO* object) { return std::make_shared<FunctorTemplate<void, R, O, false, Params...>>(functionPointer, object); } 
    template <class R, class O, class OO, class... Params> inline FunctorMemberPtr<O> createFunctor(R (O::*functionPointer)(Params...) const, OO* object) { return std::make_shared<FunctorTemplate<void, R, O, true,  Params...>>(functionPointer, object); } 

    template <class R, class O, class... Params> inline FunctorMemberPtr<O> createFunctor(R (O::*functionPointer)(Params...))       { return std::make_shared<FunctorTemplate<void, R, O, false, Params...>>(functionPointer); } 
    template <class R, class O, class... Params> inline FunctorMemberPtr<O> createFunctor(R (O::*functionPointer)(Params...) const) { return std::make_shared<FunctorTemplate<void, R, O, true,  Params...>>(functionPointer); } 

    template <class R, class... Params> inline FunctorStaticPtr createFunctor(R (*functionPointer)(Params...)) { return std::make_shared<FunctorTemplate<void, R, void, false, Params...>>(functionPointer); } 

    template <class F> inline FunctorStaticPtr createFunctor(const F& functionObject) { return detail::CallableHelper<F>::create(functionObject, &F::operator()); } 
}

#endif /* _Functor_H__ */