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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#ifndef DUNE_COMMON_PARAMETERIZEDOBJECT_HH
#define DUNE_COMMON_PARAMETERIZEDOBJECT_HH
#include <functional>
#include <map>
#include <memory>
#include <dune/common/exceptions.hh>
#include <dune/common/typeutilities.hh>
namespace Dune {
/**
* @brief A factory class for parameterized objects.
*
* It allows the construction of objects adhering to a certain interface that
* might be constructed quite differently for one another.
*
* The Signature parameter defined the "virtual" constructor signature
* in the form of Interface(Args...), where Interface is the type of
* the (abstract) interface class and Args... is the set of
* constructor parameters.
*
* Each type constructed by this factory is identified by a different key. This class
* allows for easy registration of type with new keys.
*
* @tparam Signature Signature of the "virtual" constructor call in the form for Interface(Args...). For default constructors one can omit the ()-brackets.
* @tparam KeyT The type of the objects that are used as keys in the lookup [DEFAULT: std::string].
*/
template<typename Signature,
typename KeyT = std::string>
class ParameterizedObjectFactory;
template<typename TypeT,
typename KeyT,
typename... Args>
class ParameterizedObjectFactory<TypeT(Args...), KeyT>
{
public:
/** @brief The typ of the keys. */
typedef KeyT Key;
/** @brief The type of objects created by the factory. */
using Type = TypeT;
protected:
using Creator = std::function<Type(Args...)>;
template<class F>
static constexpr auto has_proper_signature(Dune::PriorityTag<1>)
-> decltype( std::declval<F>()(std::declval<Args>()...), std::true_type())
{
return {};
}
template<class F>
static constexpr std::false_type has_proper_signature(Dune::PriorityTag<0>)
{
return {};
}
public:
/**
* @brief Creates an object identified by a key from given parameters
*
* @param key The key the object is registered with @see define.
* @param args The parameters used for the construction.
* @return The object wrapped as Type
*/
Type create(Key const& key, Args ... args) const {
typename Registry::const_iterator i = registry_.find(key);
if (i == registry_.end()) {
DUNE_THROW(Dune::InvalidStateException,
"ParametrizedObjectFactory: key ``" <<
key << "'' not registered");
}
else return i->second(args...);
}
/**
* @brief Registers a new type with a key.
*
* After registration objects of this type can be constructed with the
* specified key using a matching default creation function. If Type
* is a unique_ptr or shared_ptr, the object is created via make_unique
* or make_shared, respectively. Otherwise a constructor of Impl
* is called.
*
* @tparam Impl The type of objects to create.
*
* @param key The key associated with this type.
*/
template<class Impl>
void define(Key const& key)
{
registry_[key] = DefaultCreator<Impl>();
}
/**
* @brief Registers a new creator with a key.
*
* After registration objects can be constructed using
* the given creator function.
*
* @tparam F Type of creator function. This must be callable with Args... .
*
* @param key The key associated with this type.
* @param f Function for creation of objects of type Impl
*
* \todo Replace has_proper_signature by concept check
*/
template<class F,
typename std::enable_if<has_proper_signature<F>(PriorityTag<42>()), int>::type = 0>
void define(Key const& key, F&& f)
{
registry_[key] = f;
}
/**
* @brief Registers a new type with a key.
*
* After registration objects of this type can be created.
* This method will store a copy of the given object and
* create will hand out a copy to this.
*
* @tparam Impl The type of objects to create.
*
* @param key The key associated with this type.
* @param t reference object, "create" will call the copy-constructor
*
* note, this does not work fundamental types
*/
template<class Impl,
typename std::enable_if<
std::is_convertible<Impl, Type>::value
and not std::is_convertible<Impl, Creator>::value,
int>::type = 0>
void define(Key const& key, Impl&& t)
{
registry_[key] = [=](Args...) { return t;};
}
bool contains(Key const& key) const
{
return registry_.count(key);
}
private:
template<class T>
struct Tag{};
template<class Impl>
struct DefaultCreator
{
template<class... T>
Type operator()(T&&... args) const
{
return DefaultCreator::create(Tag<Type>(), PriorityTag<42>(), std::forward<T>(args)...);
}
template<class Target, class... T>
static Type create(Tag<Target>, PriorityTag<1>, T&& ... args) {
return Impl(std::forward<T>(args)...);
}
template<class Target, class... T>
static Type create(Tag<std::unique_ptr<Target>>, PriorityTag<2>, T&& ... args) {
return std::make_unique<Impl>(std::forward<T>(args)...);
}
template<class Target, class... T>
static Type create(Tag<std::shared_ptr<Target>>, PriorityTag<3>, T&& ... args) {
return std::make_shared<Impl>(std::forward<T>(args)...);
}
};
typedef std::map<Key, Creator> Registry;
Registry registry_;
};
} // end namespace Dune
#endif // DUNE_COMMON_PARAMETERIZEDOBJECT_HH
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