delegate_cpp11.h

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/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2019 John Wellbelove
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
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copies or substantial portions of the Software.
 
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/******************************************************************************
 
Copyright (C) 2017 by Sergey A Kryukov: derived work
http://www.SAKryukov.org
http://www.codeproject.com/Members/SAKryukov
 
Based on original work by Sergey Ryazanov:
"The Impossibly Fast C++ Delegates", 18 Jul 2005
https://www.codeproject.com/articles/11015/the-impossibly-fast-c-delegates
 
MIT license:
http://en.wikipedia.org/wiki/MIT_License
 
Original publication: https://www.codeproject.com/Articles/1170503/The-Impossibly-Fast-Cplusplus-Delegates-Fixed
 
******************************************************************************/
 
#ifndef ETL_DELEGATE_CPP11_INCLUDED
#define ETL_DELEGATE_CPP11_INCLUDED
 
#include "../platform.h"
#include "../error_handler.h"
#include "../exception.h"
#include "../type_traits.h"
#include "../utility.h"
#include "../optional.h"
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class delegate_exception : public exception
  {
  public:
 
    delegate_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
      : exception(reason_, file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class delegate_uninitialised : public delegate_exception
  {
  public:
 
    delegate_uninitialised(string_type file_name_, numeric_type line_number_)
      : delegate_exception(ETL_ERROR_TEXT("delegate:uninitialised", ETL_DELEGATE_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };
 
  //*************************************************************************
  //*************************************************************************
  template <typename T> class delegate;
 
  //*************************************************************************
  //*************************************************************************
  template <typename TReturn, typename... TParams>
  class delegate<TReturn(TParams...)> final
  {
  public:
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 delegate()
    {
    }
 
    //*************************************************************************
    // Copy constructor.
    //*************************************************************************
    ETL_CONSTEXPR14 delegate(const delegate& other) = default;
 
    //*************************************************************************
    // Construct from lambda or functor.
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_CONSTEXPR14 delegate(TLambda& instance)
    {
      assign((void*)(&instance), lambda_stub<TLambda>);
    }
 
    //*************************************************************************
    // Construct from const lambda or functor.
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_CONSTEXPR14 delegate(const TLambda& instance)
    {
      assign((void*)(&instance), const_lambda_stub<TLambda>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <TReturn(*Method)(TParams...)>
    ETL_NODISCARD
    static ETL_CONSTEXPR14 delegate create()
    {
      return delegate(ETL_NULLPTR, function_stub<Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_NODISCARD
    static ETL_CONSTEXPR14 delegate create(TLambda& instance)
    {
      return delegate((void*)(&instance), lambda_stub<TLambda>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_NODISCARD
      static ETL_CONSTEXPR14 delegate create(const TLambda& instance)
    {
      return delegate((void*)(&instance), const_lambda_stub<TLambda>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::*Method)(TParams...)>
    ETL_NODISCARD
    static ETL_CONSTEXPR14 delegate create(T& instance)
    {
      return delegate((void*)(&instance), method_stub<T, Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::*Method)(TParams...)>
    ETL_NODISCARD
    static ETL_CONSTEXPR14 delegate create(T&& instance) = delete;
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::*Method)(TParams...) const>
    ETL_NODISCARD
    static ETL_CONSTEXPR14 delegate create(const T& instance)
    {
      return delegate((void*)(&instance), const_method_stub<T, Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::*Method)(TParams...) const>
    static ETL_CONSTEXPR14 delegate create(T&& instance) = delete;
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, T& Instance, TReturn(T::*Method)(TParams...)>
    ETL_NODISCARD
    static ETL_CONSTEXPR14 delegate create()
    {
      return delegate(method_instance_stub<T, Instance, Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, T const& Instance, TReturn(T::*Method)(TParams...) const>
    ETL_NODISCARD
    static ETL_CONSTEXPR14 delegate create()
    {
      return delegate(const_method_instance_stub<T, Instance, Method>);
    }
 
#if !(defined(ETL_COMPILER_GCC) && (__GNUC__ <= 8))
    //*************************************************************************
    //*************************************************************************
    template <typename T, T& Instance>
    ETL_NODISCARD
      static ETL_CONSTEXPR14 delegate create()
    {
      return delegate(operator_instance_stub<T, Instance>);
    }
#endif
 
    //*************************************************************************
    //*************************************************************************
    template <TReturn(*Method)(TParams...)>
    ETL_CONSTEXPR14 void set()
    {
      assign(ETL_NULLPTR, function_stub<Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_CONSTEXPR14 void set(TLambda& instance)
    {
      assign((void*)(&instance), lambda_stub<TLambda>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_CONSTEXPR14 void set(const TLambda& instance)
    {
      assign((void*)(&instance), const_lambda_stub<TLambda>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::* Method)(TParams...)>
    ETL_CONSTEXPR14 void set(T& instance)
    {
      assign((void*)(&instance), method_stub<T, Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::* Method)(TParams...) const>
    ETL_CONSTEXPR14 void set(T& instance)
    {
      assign((void*)(&instance), const_method_stub<T, Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, T& Instance, TReturn(T::* Method)(TParams...)>
    ETL_CONSTEXPR14 void set()
    {
      assign(ETL_NULLPTR, method_instance_stub<T, Instance, Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, T const& Instance, TReturn(T::* Method)(TParams...) const>
    ETL_CONSTEXPR14 void set()
    {
      assign(ETL_NULLPTR, const_method_instance_stub<T, Instance, Method>);
    }
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 void clear()
    {
      invocation.clear();
    }
 
    //*************************************************************************
    //*************************************************************************
    TReturn operator()(TParams... args) const
    {
      ETL_ASSERT(is_valid(), ETL_ERROR(delegate_uninitialised));
 
      return (*invocation.stub)(invocation.object, etl::forward<TParams>(args)...);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TRet = TReturn>
    typename etl::enable_if_t<etl::is_same<TRet, void>::value, bool>
      call_if(TParams... args) const
    {
      if (is_valid())
      {
        (*invocation.stub)(invocation.object, etl::forward<TParams>(args)...);
        return true;
      }
      else
      {
        return false;
      }
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TRet = TReturn>
    typename etl::enable_if_t<!etl::is_same<TRet, void>::value, etl::optional<TReturn>>
      call_if(TParams... args) const
    {
      etl::optional<TReturn> result;
 
      if (is_valid())
      {
        result = (*invocation.stub)(invocation.object, etl::forward<TParams>(args)...);
      }
 
      return result;
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TAlternative>
    TReturn call_or(TAlternative alternative, TParams... args) const
    {
      if (is_valid())
      {
        return (*invocation.stub)(invocation.object, etl::forward<TParams>(args)...);
      }
      else
      {
        return alternative(etl::forward<TParams>(args)...);
      }
    }
 
    //*************************************************************************
    //*************************************************************************
    template <TReturn(*Method)(TParams...)>
    TReturn call_or(TParams... args) const
    {
      if (is_valid())
      {
        return (*invocation.stub)(invocation.object, etl::forward<TParams>(args)...);
      }
      else
      {
        return (Method)(etl::forward<TParams>(args)...);
      }
    }
 
    //*************************************************************************
    //*************************************************************************
    delegate& operator =(const delegate& rhs) = default;
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_CONSTEXPR14 delegate& operator =(TLambda& instance)
    {
      assign((void*)(&instance), lambda_stub<TLambda>);
      return *this;
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda, typename = etl::enable_if_t<etl::is_class<TLambda>::value && !etl::is_same<etl::delegate<TReturn(TParams...)>, TLambda>::value, void>>
    ETL_CONSTEXPR14 delegate& operator =(const TLambda& instance)
    {
      assign((void*)(&instance), const_lambda_stub<TLambda>);
      return *this;
    }
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 bool operator == (const delegate& rhs) const
    {
      return invocation == rhs.invocation;
    }
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 bool operator != (const delegate& rhs) const
    {
      return invocation != rhs.invocation;
    }
 
    //*************************************************************************
    //*************************************************************************
    ETL_NODISCARD
    ETL_CONSTEXPR14 bool is_valid() const
    {
      return invocation.stub != ETL_NULLPTR;
    }
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 operator bool() const
    {
      return is_valid();
    }
 
  private:
 
    using stub_type = TReturn(*)(void* object, TParams...);
 
    //*************************************************************************
    //*************************************************************************
    struct invocation_element
    {
      invocation_element() = default;
 
      //***********************************************************************
      ETL_CONSTEXPR14 invocation_element(void* object_, stub_type stub_)
        : object(object_)
        , stub(stub_)
      {
      }
 
      //***********************************************************************
      ETL_CONSTEXPR14 bool operator ==(const invocation_element& rhs) const
      {
        return (rhs.stub == stub) && (rhs.object == object);
      }
 
      //***********************************************************************
      ETL_CONSTEXPR14 bool operator !=(const invocation_element& rhs) const
      {
        return (rhs.stub != stub) || (rhs.object != object);
      }
 
      //***********************************************************************
      ETL_CONSTEXPR14 void clear()
      {
        object = ETL_NULLPTR;
        stub   = ETL_NULLPTR;
      }
 
      //***********************************************************************
      void*     object = ETL_NULLPTR;
      stub_type stub   = ETL_NULLPTR;
    };
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 delegate(void* object, stub_type stub)
      : invocation(object, stub)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 delegate(stub_type stub)
      : invocation(ETL_NULLPTR, stub)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    ETL_CONSTEXPR14 void assign(void* object, stub_type stub)
    {
      invocation.object = object;
      invocation.stub   = stub;
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::*Method)(TParams...)>
    static ETL_CONSTEXPR14 TReturn method_stub(void* object, TParams... params)
    {
      T* p = static_cast<T*>(object);
      return (p->*Method)(etl::forward<TParams>(params)...);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, TReturn(T::*Method)(TParams...) const>
    static ETL_CONSTEXPR14 TReturn const_method_stub(void* object, TParams... params)
    {
      T* const p = static_cast<T*>(object);
      return (p->*Method)(etl::forward<TParams>(params)...);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, T& Instance, TReturn(T::*Method)(TParams...)>
    static ETL_CONSTEXPR14 TReturn method_instance_stub(void*, TParams... params)
    {
      return (Instance.*Method)(etl::forward<TParams>(params)...);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename T, const T& Instance, TReturn(T::*Method)(TParams...) const>
    static ETL_CONSTEXPR14 TReturn const_method_instance_stub(void*, TParams... params)
    {
      return (Instance.*Method)(etl::forward<TParams>(params)...);
    }
 
#if !(defined(ETL_COMPILER_GCC) && (__GNUC__ <= 8))
    //*************************************************************************
    //*************************************************************************
    template <typename T, T& Instance>
    static ETL_CONSTEXPR14 TReturn operator_instance_stub(void*, TParams... params)
    {
      return Instance.operator()(etl::forward<TParams>(params)...);
    }
#endif
 
    //*************************************************************************
    //*************************************************************************
    template <TReturn(*Method)(TParams...)>
    static ETL_CONSTEXPR14 TReturn function_stub(void*, TParams... params)
    {
      return (Method)(etl::forward<TParams>(params)...);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda>
    static ETL_CONSTEXPR14 TReturn lambda_stub(void* object, TParams... arg)
    {
      TLambda* p = static_cast<TLambda*>(object);
      return (p->operator())(etl::forward<TParams>(arg)...);
    }
 
    //*************************************************************************
    //*************************************************************************
    template <typename TLambda>
    static ETL_CONSTEXPR14 TReturn const_lambda_stub(void* object, TParams... arg)
    {
      const TLambda* p = static_cast<const TLambda*>(object);
      return (p->operator())(etl::forward<TParams>(arg)...);
    }
 
    //*************************************************************************
    //*************************************************************************
    invocation_element invocation;
  };
}
 
#endif