path: root/Gem/develop/include/Gem/Utils/any.h

/*
 * (C) Copyright Christopher Diggins 2005
 * (C) Copyright Pablo Aguilar 2005
 * (C) Copyright Kevlin Henney 2001
 *
 * Copyright (C) 2010-2011 IOhannes m zmölnig. forum::für::umläute. IEM. zmoelnig@iem.at
 *       downloaded this code from http://www.codeproject.com/KB/cpp/dynamic_typing.aspx
 *         changed namespace/defines "cdiggins" to something "gem"
 *
 * Distributed under the Boost Software License, Version 1.0. (See
 * accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 */

#ifndef GEM_ANY_HPP
#define GEM_ANY_HPP

#include "Gem/ExportDef.h"

#ifdef _MSC_VER
# pragma warning( push )
# pragma warning( disable: 4275 )
#endif

#include <stdexcept>
#include <typeinfo>
#include <algorithm>
#include <string>

//#define GEM_ANY_TYPEID_HACK

namespace gem
{
struct GEM_EXTERN bad_any_cast : std::bad_cast {
  bad_any_cast(const std::type_info& src, const std::type_info& dest)
    : result(std::string("bad cast (")+src.name() + "->" + dest.name()+")")
  { }
  virtual ~bad_any_cast(void)
#if __cplusplus <= 199711L
  throw()
#endif
  { }
  virtual const char* what(void) const
#if __cplusplus > 199711L
  noexcept
#else
  throw()
#endif
  {
    return result.c_str();
  }
  const std::string result;
};

namespace any_detail
{
// function pointer table

struct fxn_ptr_table {
  const std::type_info& (*get_type)(void);
  void (*static_delete)(void**);
  void (*clone)(void* const*, void**);
  void (*move)(void* const*,void**);
};

// static functions for small value-types

template<bool is_small>
struct fxns {
  template<typename T>
  struct type {
    static const std::type_info& get_type(void)
    {
#if GEM_ANY_TYPEID_HACK
      const std::type_info&res=typeid(T);
      // the following is a dummy use of the type_info struct
      // to make the template engine work properly on OSX/10.9
      static std::string _ = res.name();
      return res;
#else
      return typeid(T);
#endif
    }
    static void static_delete(void** x)
    {
      reinterpret_cast<T*>(x)->~T();
    }
    static void clone(void* const* src, void** dest)
    {
      new(dest) T(*reinterpret_cast<T const*>(src));
    }
    static void move(void* const* src, void** dest)
    {
      reinterpret_cast<T*>(dest)->~T();
      *reinterpret_cast<T*>(dest) = *reinterpret_cast<T const*>(src);
    }
  };
};

// static functions for big value-types (bigger than a void*)

template<>
struct fxns<false> {
  template<typename T>
  struct type {
    static const std::type_info& get_type(void)
    {
#if GEM_ANY_TYPEID_HACK
      const std::type_info&res=typeid(T);
      return res;
#else
      return typeid(T);
#endif
    }
    static void static_delete(void** x)
    {
      delete(*reinterpret_cast<T**>(x));
    }
    static void clone(void* const* src, void** dest)
    {
      *dest = new T(**reinterpret_cast<T* const*>(src));
    }
    static void move(void* const* src, void** dest)
    {
      (*reinterpret_cast<T**>(dest))->~T();
      **reinterpret_cast<T**>(dest) = **reinterpret_cast<T* const*>(src);
    }
  };
};

template<typename T>
struct get_table {
  static const bool is_small = sizeof(T) <= sizeof(void*);

  static fxn_ptr_table* get(void)
  {
    static fxn_ptr_table static_table = {
      fxns<is_small>::template type<T>::get_type
      , fxns<is_small>::template type<T>::static_delete
      , fxns<is_small>::template type<T>::clone
      , fxns<is_small>::template type<T>::move
    };
    return &static_table;
  }
};

struct empty {
};
} // namespace any_detail


struct GEM_EXTERN any {
  // structors

  template <typename T>
  any(const T& x) : table(NULL), object(NULL)
  {
    table = any_detail::get_table<T>::get();
#if defined(__GNUC__) && __GNUC__ >= 6
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wplacement-new"
#endif
    if (sizeof(T) <= sizeof(void*)) {
      new(&object) T(x);
    } else {
      object = new T(x);
    }
#if defined(__GNUC__) && __GNUC__ >= 6
# pragma GCC diagnostic pop
#endif
  }

  any(void) : table(NULL), object(NULL)
  {
    table = any_detail::get_table<any_detail::empty>::get();
    object = NULL;
  }

  any(const any& x) : table(NULL), object(NULL)
  {
    table = any_detail::get_table<any_detail::empty>::get();
    assign(x);
  }

  virtual ~any(void)
  {
    table->static_delete(&object);
  }

  // assignment

  any& assign(const any& x)
  {
    // are we copying between the same type?

    if (table == x.table) {
      // if so, we can avoid reallocation

      table->move(&x.object, &object);
    } else {
      reset();
      x.table->clone(&x.object, &object);
      table = x.table;
    }
    return *this;
  }

  template <typename T>
  any& assign(const T& x)
  {
    // are we copying between the same type?

    any_detail::fxn_ptr_table* x_table = any_detail::get_table<T>::get();
    if (table == x_table) {
      // if so, we can avoid deallocating and resuse memory

#if defined(__GNUC__) && __GNUC__ >= 6
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wplacement-new"
#endif
      if (sizeof(T) <= sizeof(void*)) {
        // create copy on-top of object pointer itself
        new(&object) T(x);
      } else {
        // create copy on-top of old version
        new(object) T(x);
      }
    } else {
      reset();
      if (sizeof(T) <= sizeof(void*)) {
        // create copy on-top of object pointer itself
        new(&object) T(x);
        // update table pointer
        table = x_table;
      } else {
        object = new T(x);
        table = x_table;
      }
#if defined(__GNUC__) && __GNUC__ >= 6
# pragma GCC diagnostic pop
#endif
    }
    return *this;
  }

  // assignment operator

  template<typename T>
  any& operator=(T const& x)
  {
    return assign(x);
  }
  any& operator=(const any& x)
  {
    return assign(x);
  }

  // utility functions

  any& swap(any& x)
  {
    std::swap(table, x.table);
    std::swap(object, x.object);
    return *this;
  }

  const std::type_info& get_type(void) const
  {
    return table->get_type();
  }

  template<typename T>
  const T& cast(void) const
  {
    if (!compatible<T>()) {
      throw bad_any_cast(get_type(), typeid(T));
    }
    if (sizeof(T) <= sizeof(void*)) {
      return *reinterpret_cast<T const*>(&object);
    } else {
      return *reinterpret_cast<T const*>(object);
    }
  }

  /// Returns true if the two types are the same.
  bool compatible(const any& x) const
  {
    return get_type() == x.get_type();
  }
  /// Returns true if the two types are the same.
  template<typename T>
  bool compatible() const
  {
    return (get_type() == typeid(T));
  }

  // implicit casting is disabled by default

#ifdef ANY_IMPLICIT_CASTING
  // automatic casting operator

  template<typename T>
  operator T(void) const
  {
    return cast<T>();
  }
#endif // implicit casting


  bool empty(void) const
  {
    return table == any_detail::get_table<any_detail::empty>::get();
  }

  void reset(void)
  {
    if (empty()) {
      return;
    }
    table->static_delete(&object);
    table = any_detail::get_table<any_detail::empty>::get();
    object = NULL;
  }

  // fields

  any_detail::fxn_ptr_table* table;
  void* object;
};

// boost::any-like casting

template<typename T>
T* any_cast(any* this_)
{
  if (this_->get_type() != typeid(T)) {
    throw bad_any_cast(this_->get_type(), typeid(T));
  }
  if (sizeof(T) <= sizeof(void*)) {
    return reinterpret_cast<T*>(&this_->object);
  } else {
    return reinterpret_cast<T*>(this_->object);
  }
}

template<typename T>
T const* any_cast(any const* this_)
{
  return any_cast<T>(const_cast<any*>(this_));
}

template<typename T>
T const& any_cast(any const& this_)
{
  return *any_cast<T>(const_cast<any*>(&this_));
}
#ifdef GEM_INTERNAL
// Note: The "unsafe" versions of any_cast are not part of the
// public interface (and hence protected by GEM_INTERNAL) and may
// be removed at any time. They are required where we know what type
// is stored in the any and can't use typeid() comparison, e.g.,
// when our types may travel across different shared libraries.
template<typename T>
T* unsafe_any_cast(any* this_)
{
  if (sizeof(T) <= sizeof(void*)) {
    return reinterpret_cast<T*>(&this_->object);
  } else {
    return reinterpret_cast<T*>(this_->object);
  }
}

template<typename T>
T const* unsafe_any_cast(any const* this_)
{
  return unsafe_any_cast<T>(const_cast<any*>(this_));
}

template<typename T>
T const& unsafe_any_cast(any const& this_)
{
  return *unsafe_any_cast<T>(const_cast<any*>(&this_));
}
#endif
}

#ifdef _MSC_VER
# pragma warning( pop )
#endif

#endif // GEM_ANY_HPP