callback.h

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/*
 * Copyright (c) 2005,2006 INRIA
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Authors: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
 *          Stefano Avallone <stavallo@unina.it>
 */
 
#ifndef CALLBACK_H
#define CALLBACK_H
 
#include "attribute-helper.h"
#include "attribute.h"
#include "fatal-error.h"
#include "ptr.h"
#include "simple-ref-count.h"
 
#include <functional>
#include <memory>
#include <typeinfo>
#include <utility>
#include <vector>
 
namespace ns3
{
 
// Define the doxygen subgroups all at once,
// since the implementations are interleaved.
 
class CallbackImplBase : public SimpleRefCount<CallbackImplBase>
{
  public:
    virtual ~CallbackImplBase()
    {
    }
 
    virtual bool IsEqual(Ptr<const CallbackImplBase> other) const = 0;
    virtual std::string GetTypeid() const = 0;
 
  protected:
    static std::string Demangle(const std::string& mangled);
 
    template <typename T>
    static std::string GetCppTypeid()
    {
        std::string typeName;
        try
        {
            typeName = typeid(T).name();
            typeName = Demangle(typeName);
        }
        catch (const std::bad_typeid& e)
        {
            typeName = e.what();
        }
        return typeName;
    }
};
 
class CallbackComponentBase
{
  public:
    virtual ~CallbackComponentBase()
    {
    }
 
    virtual bool IsEqual(std::shared_ptr<const CallbackComponentBase> other) const = 0;
};
 
template <typename T, bool isComparable = true>
class CallbackComponent : public CallbackComponentBase
{
  public:
    CallbackComponent(const T& t)
        : m_comp(t)
    {
    }
 
    bool IsEqual(std::shared_ptr<const CallbackComponentBase> other) const override
    {
        auto p = std::dynamic_pointer_cast<const CallbackComponent<T>>(other);
 
        // other must have the same type and value as ours
        if (p == nullptr || p->m_comp != m_comp)
        {
            return false;
        }
 
        return true;
    }
 
  private:
    T m_comp; 
};
 
template <typename T>
class CallbackComponent<T, false> : public CallbackComponentBase
{
  public:
    CallbackComponent(const T& t)
    {
    }
 
    bool IsEqual(std::shared_ptr<const CallbackComponentBase> other) const override
    {
        return false;
    }
};
 
typedef std::vector<std::shared_ptr<CallbackComponentBase>> CallbackComponentVector;
 
template <typename R, typename... UArgs>
class CallbackImpl : public CallbackImplBase
{
  public:
    CallbackImpl(std::function<R(UArgs...)> func, const CallbackComponentVector& components)
        : m_func(func),
          m_components(components)
    {
    }
 
    const std::function<R(UArgs...)>& GetFunction() const
    {
        return m_func;
    }
 
    const CallbackComponentVector& GetComponents() const
    {
        return m_components;
    }
 
    R operator()(UArgs... uargs) const
    {
        return m_func(uargs...);
    }
 
    bool IsEqual(Ptr<const CallbackImplBase> other) const override
    {
        const CallbackImpl<R, UArgs...>* otherDerived =
            dynamic_cast<const CallbackImpl<R, UArgs...>*>(PeekPointer(other));
 
        if (otherDerived == nullptr)
        {
            return false;
        }
 
        // if the two callback implementations are made of a distinct number of
        // components, they are different
        if (m_components.size() != otherDerived->GetComponents().size())
        {
            return false;
        }
 
        // the two functions are equal if they compare equal or the shared pointers
        // point to the same locations
        if (!m_components.at(0)->IsEqual(otherDerived->GetComponents().at(0)) &&
            m_components.at(0) != otherDerived->GetComponents().at(0))
        {
            return false;
        }
 
        // check if the remaining components are equal one by one
        for (std::size_t i = 1; i < m_components.size(); i++)
        {
            if (!m_components.at(i)->IsEqual(otherDerived->GetComponents().at(i)))
            {
                return false;
            }
        }
 
        return true;
    }
 
    std::string GetTypeid() const override
    {
        return DoGetTypeid();
    }
 
    static std::string DoGetTypeid()
    {
        static std::vector<std::string> vec = {GetCppTypeid<R>(), GetCppTypeid<UArgs>()...};
 
        static std::string id("CallbackImpl<");
        for (auto& s : vec)
        {
            id.append(s + ",");
        }
        if (id.back() == ',')
        {
            id.pop_back();
        }
        id.push_back('>');
 
        return id;
    }
 
  private:
    std::function<R(UArgs...)> m_func;
 
    std::vector<std::shared_ptr<CallbackComponentBase>> m_components;
};
 
class CallbackBase
{
  public:
    CallbackBase()
        : m_impl()
    {
    }
 
    Ptr<CallbackImplBase> GetImpl() const
    {
        return m_impl;
    }
 
  protected:
    CallbackBase(Ptr<CallbackImplBase> impl)
        : m_impl(impl)
    {
    }
 
    Ptr<CallbackImplBase> m_impl; 
};
 
template <typename R, typename... UArgs>
class Callback : public CallbackBase
{
    template <typename ROther, typename... UArgsOther>
    friend class Callback;
 
  public:
    Callback()
    {
    }
 
    Callback(const Ptr<CallbackImpl<R, UArgs...>>& impl)
        : CallbackBase(impl)
    {
    }
 
    template <typename... BArgs>
    Callback(const Callback<R, BArgs..., UArgs...>& cb, BArgs... bargs)
    {
        auto f = cb.DoPeekImpl()->GetFunction();
 
        CallbackComponentVector components(cb.DoPeekImpl()->GetComponents());
        components.insert(components.end(), {std::make_shared<CallbackComponent<BArgs>>(bargs)...});
 
        m_impl = Create<CallbackImpl<R, UArgs...>>(
            [f, bargs...](auto&&... uargs) -> R {
                return f(bargs..., std::forward<decltype(uargs)>(uargs)...);
            },
            components);
    }
 
    template <typename T,
              std::enable_if_t<!std::is_base_of_v<CallbackBase, T>, int> = 0,
              typename... BArgs>
    Callback(T func, BArgs... bargs)
    {
        // store the function in a std::function object
        std::function<R(BArgs..., UArgs...)> f(func);
 
        // The original function is comparable if it is a function pointer or
        // a pointer to a member function or a pointer to a member data.
        constexpr bool isComp =
            std::is_function_v<std::remove_pointer_t<T>> || std::is_member_pointer_v<T>;
 
        CallbackComponentVector components({std::make_shared<CallbackComponent<T, isComp>>(func),
                                            std::make_shared<CallbackComponent<BArgs>>(bargs)...});
 
        m_impl = Create<CallbackImpl<R, UArgs...>>(
            [f, bargs...](auto&&... uargs) -> R {
                return f(bargs..., std::forward<decltype(uargs)>(uargs)...);
            },
            components);
    }
 
  private:
    template <std::size_t... INDEX, typename... BoundArgs>
    auto BindImpl(std::index_sequence<INDEX...> seq, BoundArgs&&... bargs)
    {
        Callback<R, std::tuple_element_t<sizeof...(bargs) + INDEX, std::tuple<UArgs...>>...> cb;
 
        const auto f = DoPeekImpl()->GetFunction();
 
        CallbackComponentVector components(DoPeekImpl()->GetComponents());
        components.insert(components.end(),
                          {std::make_shared<CallbackComponent<BoundArgs>>(bargs)...});
 
        cb.m_impl = Create<std::remove_pointer_t<decltype(cb.DoPeekImpl())>>(
            [f, bargs...](auto&&... uargs) mutable {
                return f(bargs..., std::forward<decltype(uargs)>(uargs)...);
            },
            components);
 
        return cb;
    }
 
  public:
    template <typename... BoundArgs>
    auto Bind(BoundArgs&&... bargs)
    {
        static_assert(sizeof...(UArgs) > 0);
        return BindImpl(std::make_index_sequence<sizeof...(UArgs) - sizeof...(BoundArgs)>{},
                        std::forward<BoundArgs>(bargs)...);
    }
 
    bool IsNull() const
    {
        return (DoPeekImpl() == nullptr);
    }
 
    void Nullify()
    {
        m_impl = nullptr;
    }
 
    R operator()(UArgs... uargs) const
    {
        return (*(DoPeekImpl()))(uargs...);
    }
 
    bool IsEqual(const CallbackBase& other) const
    {
        return m_impl->IsEqual(other.GetImpl());
    }
 
    bool CheckType(const CallbackBase& other) const
    {
        return DoCheckType(other.GetImpl());
    }
 
    bool Assign(const CallbackBase& other)
    {
        auto otherImpl = other.GetImpl();
        if (!DoCheckType(otherImpl))
        {
            std::string othTid = otherImpl->GetTypeid();
            std::string myTid = CallbackImpl<R, UArgs...>::DoGetTypeid();
            NS_FATAL_ERROR_CONT("Incompatible types. (feed to \"c++filt -t\" if needed)"
                                << std::endl
                                << "got=" << othTid << std::endl
                                << "expected=" << myTid);
            return false;
        }
        m_impl = const_cast<CallbackImplBase*>(PeekPointer(otherImpl));
        return true;
    }
 
  private:
    CallbackImpl<R, UArgs...>* DoPeekImpl() const
    {
        return static_cast<CallbackImpl<R, UArgs...>*>(PeekPointer(m_impl));
    }
 
    bool DoCheckType(Ptr<const CallbackImplBase> other) const
    {
        if (other && dynamic_cast<const CallbackImpl<R, UArgs...>*>(PeekPointer(other)) != nullptr)
        {
            return true;
        }
        else if (!other)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
};
 
template <typename R, typename... Args>
bool
operator!=(Callback<R, Args...> a, Callback<R, Args...> b)
{
    return !a.IsEqual(b);
}
 
template <typename T, typename OBJ, typename R, typename... Args>
Callback<R, Args...>
MakeCallback(R (T::*memPtr)(Args...), OBJ objPtr)
{
    return Callback<R, Args...>(memPtr, objPtr);
}
 
template <typename T, typename OBJ, typename R, typename... Args>
Callback<R, Args...>
MakeCallback(R (T::*memPtr)(Args...) const, OBJ objPtr)
{
    return Callback<R, Args...>(memPtr, objPtr);
}
 
template <typename R, typename... Args>
Callback<R, Args...>
MakeCallback(R (*fnPtr)(Args...))
{
    return Callback<R, Args...>(fnPtr);
}
 
template <typename R, typename... Args>
Callback<R, Args...>
MakeNullCallback()
{
    return Callback<R, Args...>();
}
 
template <typename R, typename... Args, typename... BArgs>
auto
MakeBoundCallback(R (*fnPtr)(Args...), BArgs&&... bargs)
{
    return Callback<R, Args...>(fnPtr).Bind(std::forward<BArgs>(bargs)...);
}
 
template <typename T, typename OBJ, typename R, typename... Args, typename... BArgs>
auto
MakeCallback(R (T::*memPtr)(Args...), OBJ objPtr, BArgs... bargs)
{
    return Callback<R, Args...>(memPtr, objPtr).Bind(bargs...);
}
 
template <typename T, typename OBJ, typename R, typename... Args, typename... BArgs>
auto
MakeCallback(R (T::*memPtr)(Args...) const, OBJ objPtr, BArgs... bargs)
{
    return Callback<R, Args...>(memPtr, objPtr).Bind(bargs...);
}
 
} // namespace ns3
 
namespace ns3
{
 
class CallbackValue : public AttributeValue
{
  public:
    CallbackValue();
    CallbackValue(const CallbackBase& base);
    ~CallbackValue() override;
    void Set(CallbackBase base);
    /* Documented by print-introspected-doxygen.cc */
    template <typename T>
    bool GetAccessor(T& value) const;
    Ptr<AttributeValue> Copy() const override;
    std::string SerializeToString(Ptr<const AttributeChecker> checker) const override;
    bool DeserializeFromString(std::string value, Ptr<const AttributeChecker> checker) override;
 
  private:
    /* Documented by print-introspected-doxygen.cc */
    CallbackBase m_value;
};
 
ATTRIBUTE_ACCESSOR_DEFINE(Callback);
ATTRIBUTE_CHECKER_DEFINE(Callback);
 
} // namespace ns3
 
namespace ns3
{
 
template <typename T>
bool
CallbackValue::GetAccessor(T& value) const
{
    if (value.CheckType(m_value))
    {
        if (!value.Assign(m_value))
        {
            NS_FATAL_ERROR_NO_MSG();
        }
        return true;
    }
    return false;
}
 
} // namespace ns3
 
#endif /* CALLBACK_H */