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FunctorFactory.h
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FunctorFactory.h
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/*!
* \author Kenneth Earl Cornett Jr.
* \date 2017.05.13
* \file FunctorFactory.h
*
* \copyright
* FunctorFactory is a Factory Design Program which brings portability
* and ease to implementing a Factory Design Pattern into a project.
*
* Copyright (C) 2017 Kenneth Earl Cornett Jr.
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#ifndef FUNCTOR_FACTORY_H
#define FUNCTOR_FACTORY_H
#include <map>
#include <string>
#include "Base.h"
namespace ASW{
/*!
* \mainpage
* \section copyr_sec Copyright
* \copyright
* FunctorFactory is a Factory Design Program which brings portability
* and ease to implementing a Factory Design Pattern into a project.
*
* Copyright (C) 2017 Kenneth Earl Cornett Jr.
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*
* \section intro_sec Introduction
*
* FunctorFactory is an example of a Factory Design Pattern which
* allows the storage of not only many derived objects of *Base*, but also
* many constructors for each derived class. As long as the arguments and
* the key are correctly known and used when requesting the creation of an
* object, then the object will be created correctly as long as it was
* registered with the FF_MACRO.
*
* Registering classes and their appropriate constructors with FF_MACRO
* also ensures proper cleanup on termination of the program.
*
* \section usage_sec Usage
* Usage for FF_MACRO
* 1. Include it in header file for the derived class.
* 2. Name does not have quotes, and can not be a C/C++ Keyword
* 3. Type is the type of the object being registered.
* 4. Any other argument must be the type of argument accepted by the constructor for the object being registered.
*
* This is a derived class from an example Base class included in this
* set.
*
* \code
*
* struct Derived : public Base{
* Derived(int, int, float);
* Derived(int, int);
* Derived(const char *);
* }
* FF_MACRO(name_1, Derived, int, int, float);
* FF_MACRO(name_2, Derived, int, int);
* FF_MACRO(name_3, Derived, const char *);
*
* Base * b = FunctorFactory::createObject<int, int, float>("name_1", 8, 8, 3.0);
* Derived * d = static_cast<Derived*>(FunctorFactory::createObject<const char*>("name_3","Hello World"));
*
* \endcode
*
* \section fin_sec Final Comments
* The way this Factory class works is once a class/constructor is
* included, memory is dynamically allocated for a DerivedFunctor
* object which stores a reference to the templated create function
* for this constructor. It is then stored in the registry map with
* the key passed in by the user.
*
* When using this structure for you personal programs, all that is
* needing to be done is switch out Base\* with [Your Base Class]\*'s
* name, then include the FF_MACRO registration in the classes you are
* wanting to register into the Factory design.
*/
struct FunctorFactory{
private:
/*!
* \namespace ASW
* \class Functor
* \brief A base class for easy storage into the registry
* mapping for the unique templated DerivedFunctors.
* \details This Functor Base class gives a common type
* for all DerivedFunctor types which inherit from this
* class.
*/
class Functor{ // Base Functor
public:
/*! \brief Destructor for the Base Functor */
virtual ~Functor(){}
};
/*!
* \class DerivedFunctor<Typename R, Typename... A>
* \brief DerivedFunctor used to store templated create
* methods from FunctorFactory class.
* \details A class designed to store templated functions,
* specifically FunctorFactory's templated static create
* method. It acts as a function by taking the Variadic
* templated arguments.
*/
template<typename R, typename... A>
struct DerivedFunctor : public Functor{ // Templated Derived Functors
/*!
* \brief Constructor for templated Derived Functor class.
* \details Regular constructor for a templated
* DerivedFunctor class.
*
* \param f A function pointer for the function this class is
* suppose to mimic.
*/
DerivedFunctor(R (*f)(A...)); // Regular Constructor
/*!
* \brief Copy Constructor for DerivedFunctor objects.
* \details The copy constructor for the DerivedFunctor
* object. It copies the Function Pointer into this object's
* function pointer.
*
* \param df A DerivedFunctor object to copy.
*/
DerivedFunctor(const DerivedFunctor<R,A...>& df); // Copy Constructor
/*!
* \brief Destructor for a DerivedFunctor object.
*/
virtual ~DerivedFunctor(); // Virtual Destructor
/*!
* \brief Overloaded () operator to give functionlike usage.
* \details Overloaded () operator to allow use of
* DerivedFunctor objects as if the are actual functions.
*
* \param args... Are the arguments required by the function
* this DerivedFunctor is representing.
* \return R is the return type for the function which this
* DerivedFunctor is representing.
* \exception Any exception which would be thrown by the
* representing Function
*/
virtual R operator()(A... args); // Overloaded () to allow function like use.
/*!
* \brief Overloaded assignment operator
* \details Overloaded assignment operator which allows this
* DerivedFunctor to represent the same function as the
* DerivedFunctor being assigned to it.
*/
virtual DerivedFunctor<R,A...>& operator=(const DerivedFunctor<R,A...>& df); // Overloaded = to allow assignment
private:
R (*_f)(A...); //!< The actual function being called when overloaded () operator is used.
};
static std::map<std::string, Functor*>& getMap() { // Map pairing string keys to their Functors(stored as Base Functors)
static std::map<std::string, ASW::FunctorFactory::Functor*> m_map; // The actual map storing the functors.
return m_map;
}
template<typename U, typename... A> // Templated create function which will create the derived objects being requested!
static Base * create(A... args);
public:
/*!
* \brief Registrator class which will register a create
* Functor to create an object of type U with A... arguments.
* \details Registers a DerivedFunctor object which acts as the
* creator for an object of type U with A... as its constructor
* arguments.
*/
template<typename U, typename... A> // Registrator class which registers objects
struct Registrator{
/*!
* \brief Constructor for Registrator
* \details A constructor for the Registrator. This is how to
* register functions in a temporary way.
*
* \param key The key to associate with this creator.
*/
Registrator(const std::string &key);
/*!
* \brief Destructor for Registrator
* \details Destructor for Registrator, deallocates the Functor
* created by the constructor of this class.
*/
virtual ~Registrator();
private:
std::string m_key;
};
/*!
* \brief Creates the object referenced by the search key.
* \details Creates the object with the constructor taking
* Args... based on the key provided.
*
* \param skey The search key for the constructor of the object
* being sought to be created.
* \param args... The arguments required by that constructor.
* \return Returns the reference to the requested object if it
* exists, else it returns 'nullptr'.
* \exception std::exception Throws an exception or any exception the
* constructor of this requested object can throw.
*/
template<typename... A>
static inline Base * createObject(const std::string &skey, A... args) {
auto it = getMap().find(skey);
if (it == getMap().end()) return nullptr;
DerivedFunctor<Base*, A...> * df = static_cast<DerivedFunctor<Base*, A...>*>(it->second);
return (*df)(args...);
}
};
}
// Implementation of the derived functor's methods
template<typename R, typename... A> // Basic Constructor.
ASW::FunctorFactory::DerivedFunctor<R,A...>::DerivedFunctor(R (*f)(A...)){
_f = f;
}
template<typename R, typename... A> // Copy Constructor.
ASW::FunctorFactory::DerivedFunctor<R,A...>::DerivedFunctor(const FunctorFactory::DerivedFunctor<R,A...>& df){
_f = df._f;
}
template<typename R, typename... A> // Destructor
ASW::FunctorFactory::DerivedFunctor<R,A...>::~DerivedFunctor(){}
// Overloaded Operators for Derived Functor
template<typename R, typename... A> // Overloaded () operator
R ASW::FunctorFactory::DerivedFunctor<R,A...>::operator()(A... args){
return _f(args...);
}
template<typename R, typename... A> // Overloaded = operator
ASW::FunctorFactory::DerivedFunctor<R,A...>& ASW::FunctorFactory::DerivedFunctor<R,A...>::operator=(const FunctorFactory::DerivedFunctor<R,A...>& df){
_f = df._f;
}
template<typename U, typename... A>
Base * ASW::FunctorFactory::create(A... args){
return new U(args...);
}
template<typename U, typename... A>
ASW::FunctorFactory::Registrator<U,A...>::Registrator(const std::string &key){
DerivedFunctor<Base*,A...> * df = new DerivedFunctor<Base*,A...>(FunctorFactory::create<U,A...>);
getMap()[key] = df;
m_key = key;
}
template<typename U, typename... A>
ASW::FunctorFactory::Registrator<U,A...>::~Registrator(){
auto it = getMap().find(m_key); // Find in case this Registrator's key still exists
if(it != getMap().end()){ // Check if it does exist
delete it->second; // If so, delete the Functor
getMap().erase(it); // Erase it from the mapping. Cleanup is important!
}
}
#ifndef FF_MACRO // The register macro to include in header files
/*!
* \def FF_MACRO(NAME, TYPE, ...)
* Registers a derived object into the factory.
* \param NAME The name to register as the key for the object (Do not use quotes).
* \param TYPE The object's type.
* \param ... The arguments' types associated with this registry's
* creation.
*/
#define FF_MACRO(NAME,TYPE,...)\
namespace { \
::ASW::FunctorFactory::Registrator<TYPE,##__VA_ARGS__> registrator_##NAME(#NAME); \
}
#endif
#endif // FUNCTOR_FACTORY_H