ResInsight/Fwk/AppFwk/cafProjectDataModel/cafFactory.h

//##################################################################################################
//
//   Custom Visualization Core library
//   Copyright (C) 2011-2013 Ceetron AS
//
//   This library may be used under the terms of either the GNU General Public License or
//   the GNU Lesser General Public License as follows:
//
//   GNU General Public License Usage
//   This library 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 library 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 at <<http://www.gnu.org/licenses/gpl.html>>
//   for more details.
//
//   GNU Lesser General Public License Usage
//   This library is free software; you can redistribute it and/or modify
//   it under the terms of the GNU Lesser General Public License as published by
//   the Free Software Foundation; either version 2.1 of the License, or
//   (at your option) any later version.
//
//   This library 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 Lesser General Public License at <<http://www.gnu.org/licenses/lgpl-2.1.html>>
//   for more details.
//
//##################################################################################################

#pragma once

#include "cafAssert.h"

#include <cstddef>
#include <map>
#include <vector>

// Taken from gtest.h
//
// Due to C++ preprocessor weirdness, we need double indirection to
// concatenate two tokens when one of them is __LINE__.  Writing
//
//   foo ## __LINE__
//
// will result in the token foo__LINE__, instead of foo followed by
// the current line number.  For more details, see
// http://www.parashift.com/c++-faq-lite/misc-technical-issues.html#faq-39.6
#define CAF_FACTORY_CONCATENATE_STRINGS( foo, bar ) CAF_FACTORY_CONCATENATE_STRINGS_IMPL_( foo, bar )
#define CAF_FACTORY_CONCATENATE_STRINGS_IMPL_( foo, bar ) foo##bar

#define CAF_UNIQUE_COMPILE_UNIT_VAR_NAME( foo ) CAF_FACTORY_CONCATENATE_STRINGS( foo, __LINE__ )

/// Macros to simplify registering entries in a factory
/// There are two, to make it possible to use two registrations in one macro

#define CAF_FACTORY_REGISTER( BaseType, TypeToCreate, KeyType, key )   \
    static bool CAF_UNIQUE_COMPILE_UNIT_VAR_NAME( my##TypeToCreate ) = \
        caf::Factory<BaseType, KeyType>::instance()->registerCreator<TypeToCreate>( key )
#define CAF_FACTORY_REGISTER2( BaseType, TypeToCreate, KeyType, key )   \
    static bool CAF_UNIQUE_COMPILE_UNIT_VAR_NAME( my2##TypeToCreate ) = \
        caf::Factory<BaseType, KeyType>::instance()->registerCreator<TypeToCreate>( key )

namespace caf
{
//==================================================================================================
/// A generic Factory class template
/// Usage:
///     Simply add the classes that is supposed to be created by the factory by doing the folowing:
///
///     caf::Factory<BaseType, KeyType>::instance()->registerCreator<TypeToCreate>(key);
///
///     This must only be done once for each TypeToCreate. It will assert if you try to do it several times.
///     This method returns a bool to make it possible to make this initialization as a static variable initialization.
///     That is useful if you do not want a centralized registering (but rather making each class register itself):
///
///     static bool uniqueVarname = caf::Factory<BaseType, KeyType>::instance()->registerCreator<TypeToCreate>(key);
///
///     You can also use the macro CAF_FACTORY_REGISTER(BaseType, TypeToCreate, KeyType, key)
///
///     See also cafPdmUiFieldEditorHandle.h for an advanced example.
///
///     When you need an object:
///
///     BaseType* newObject = caf::Factory<BaseType, KeyType>::instance()->create(key);
//==================================================================================================

template <typename BaseType, typename KeyType>
class Factory
{
    class ObjectCreatorBase;

public:
    typedef typename std::map<KeyType, ObjectCreatorBase*>::iterator iterator_type;

    static Factory<BaseType, KeyType>* instance()
    {
        static Factory<BaseType, KeyType>* fact = new Factory<BaseType, KeyType>;
        return fact;
    }

    template <typename TypeToCreate>
    bool registerCreator( const KeyType& key )
    {
        iterator_type entryIt;

        entryIt = m_factoryMap.find( key );
        if ( entryIt == m_factoryMap.end() )
        {
            m_factoryMap[key] = new ObjectCreator<TypeToCreate>();
            return true;
        }
        else
        {
            CAF_ASSERT( key != entryIt->first ); // classNameKeyword has already been used
            CAF_ASSERT( false ); // To be sure ..
            return false;
        }
    }

    BaseType* create( const KeyType& key )
    {
        iterator_type entryIt;

        entryIt = m_factoryMap.find( key );
        if ( entryIt != m_factoryMap.end() )
        {
            return entryIt->second->create();
        }
        else
        {
            return NULL;
        }
    }

    std::vector<KeyType> allKeys()
    {
        std::vector<KeyType> keys;

        iterator_type entryIt;
        for ( entryIt = m_factoryMap.begin(); entryIt != m_factoryMap.end(); ++entryIt )
        {
            keys.push_back( entryIt->first );
        }

        return keys;
    }

    void deleteCreatorObjects()
    {
        for ( auto f : m_factoryMap )
        {
            if ( f.second ) delete f.second;
        }
        m_factoryMap.clear();
    }

private:
    Factory() {}
    ~Factory()
    {
        iterator_type entryIt;

        for ( entryIt = m_factoryMap.begin(); entryIt != m_factoryMap.end(); ++entryIt )
        {
            delete ( entryIt->second );
        }
    }

    // Internal helper classes

    class ObjectCreatorBase
    {
    public:
        ObjectCreatorBase() {}
        virtual ~ObjectCreatorBase() {}
        virtual BaseType* create() = 0;
    };

    template <typename TypeToCreate>
    class ObjectCreator : public ObjectCreatorBase
    {
    public:
        BaseType* create() override { return new TypeToCreate(); }
    };

    // Map to store factory
    std::map<KeyType, ObjectCreatorBase*> m_factoryMap;
};

} // End of namespace caf