// Boost.Function library

//  Copyright Douglas Gregor 2001-2006. Use, modification and

//  distribution is subject to 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)

// For more information, see http://www.boost.org

#ifndef BOOST_FUNCTION_BASE_HEADER

#define BOOST_FUNCTION_BASE_HEADER

#include <stdexcept>

#include <string>

#include <memory>

#include <new>

#include <typeinfo>

#include <boost/config.hpp>

#include <boost/assert.hpp>

#include <boost/type_traits/is_integral.hpp>

#include <boost/type_traits/composite_traits.hpp>

#include <boost/ref.hpp>

#include <boost/mpl/if.hpp>

#include <boost/detail/workaround.hpp>

#include <boost/type_traits/alignment_of.hpp>

#ifndef BOOST_NO_SFINAE

#  include "boost/utility/enable_if.hpp"

#else

#  include "boost/mpl/bool.hpp"

#endif

#include <boost/function_equal.hpp>

// Borrowed from Boost.Python library: determines the cases where we

// need to use std::type_info::name to compare instead of operator==.

# if (defined(__GNUC__) && __GNUC__ >= 3) \

 || defined(_AIX) \

 || (   defined(__sgi) && defined(__host_mips))

#  include <cstring>

#  define BOOST_FUNCTION_COMPARE_TYPE_ID(X,Y) \

     (std::strcmp((X).name(),(Y).name()) == 0)

# else

#  define BOOST_FUNCTION_COMPARE_TYPE_ID(X,Y) ((X)==(Y))

#endif

#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 || defined(__ICL) && __ICL <= 600 || defined(__MWERKS__) && __MWERKS__ < 0x2406 && !defined(BOOST_STRICT_CONFIG)

#  define BOOST_FUNCTION_TARGET_FIX(x) x

#else

#  define BOOST_FUNCTION_TARGET_FIX(x)

#endif // not MSVC

#if defined(__sgi) && defined(_COMPILER_VERSION) && _COMPILER_VERSION <= 730 && !defined(BOOST_STRICT_CONFIG)

// Work around a compiler bug.

// boost::python::objects::function has to be seen by the compiler before the

// boost::function class template.

namespace boost { namespace python { namespace objects {

  class function;

}}}

#endif

#if defined (BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)                    \

 || defined(BOOST_BCB_PARTIAL_SPECIALIZATION_BUG)                         \

 || !(BOOST_STRICT_CONFIG || !defined(__SUNPRO_CC) || __SUNPRO_CC > 0x540)

#  define BOOST_FUNCTION_NO_FUNCTION_TYPE_SYNTAX

#endif

#if !BOOST_WORKAROUND(__BORLANDC__, < 0x600)

#  define BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor,Type)              \

      typename ::boost::enable_if_c<(::boost::type_traits::ice_not<          \

                            (::boost::is_integral<Functor>::value)>::value), \

                           Type>::type

#else

// BCC doesn't recognize this depends on a template argument and complains

// about the use of 'typename'

#  define BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor,Type)     \

      ::boost::enable_if_c<(::boost::type_traits::ice_not<          \

                   (::boost::is_integral<Functor>::value)>::value), \

                       Type>::type

#endif

#if !defined(BOOST_FUNCTION_NO_FUNCTION_TYPE_SYNTAX)

namespace boost {

#if defined(__sgi) && defined(_COMPILER_VERSION) && _COMPILER_VERSION <= 730 && !defined(BOOST_STRICT_CONFIG)

// The library shipping with MIPSpro 7.3.1.3m has a broken allocator<void>

class function_base;

template<typename Signature,

         typename Allocator = std::allocator<function_base> >

class function;

#else

template<typename Signature, typename Allocator = std::allocator<void> >

class function;

#endif

template<typename Signature, typename Allocator>

inline void swap(function<Signature, Allocator>& f1,

                 function<Signature, Allocator>& f2)

{

  f1.swap(f2);

}

} // end namespace boost

#endif // have partial specialization

namespace boost {

  namespace detail {

    namespace function {

      class X;

      /**

       * A buffer used to store small function objects in

       * boost::function. It is a union containing function pointers,

       * object pointers, and a structure that resembles a bound

       * member function pointer.

       */

      union function_buffer

      {

        // For pointers to function objects

        void* obj_ptr;

        // For pointers to std::type_info objects

        // (get_functor_type_tag, check_functor_type_tag).

        const void* const_obj_ptr;

        // For function pointers of all kinds

        mutable void (*func_ptr)();

        // For bound member pointers

        struct bound_memfunc_ptr_t {

          void (X::*memfunc_ptr)(int);

          void* obj_ptr;

        } bound_memfunc_ptr;

        // To relax aliasing constraints

        mutable char data;

      };

      /**

       * The unusable class is a placeholder for unused function arguments

       * It is also completely unusable except that it constructable from

       * anything. This helps compilers without partial specialization to

       * handle Boost.Function objects returning void.

       */

      struct unusable

      {

        unusable() {}

        template<typename T> unusable(const T&) {}

      };

      /* Determine the return type. This supports compilers that do not support

       * void returns or partial specialization by silently changing the return

       * type to "unusable".

       */

      template<typename T> struct function_return_type { typedef T type; };

      template<>

      struct function_return_type<void>

      {

        typedef unusable type;

      };

      // The operation type to perform on the given functor/function pointer

      enum functor_manager_operation_type {

        clone_functor_tag,

        destroy_functor_tag,

        check_functor_type_tag,

        get_functor_type_tag

      };

      // Tags used to decide between different types of functions

      struct function_ptr_tag {};

      struct function_obj_tag {};

      struct member_ptr_tag {};

      struct function_obj_ref_tag {};

      template<typename F>

      class get_function_tag

      {

        typedef typename mpl::if_c<(is_pointer<F>::value),

                                   function_ptr_tag,

                                   function_obj_tag>::type ptr_or_obj_tag;

        typedef typename mpl::if_c<(is_member_pointer<F>::value),

                                   member_ptr_tag,

                                   ptr_or_obj_tag>::type ptr_or_obj_or_mem_tag;

        typedef typename mpl::if_c<(is_reference_wrapper<F>::value),

                                   function_obj_ref_tag,

                                   ptr_or_obj_or_mem_tag>::type or_ref_tag;

      public:

        typedef or_ref_tag type;

      };

      // The trivial manager does nothing but return the same pointer (if we

      // are cloning) or return the null pointer (if we are deleting).

      template<typename F>

      struct reference_manager

      {

        static inline void

        get(const function_buffer& in_buffer, function_buffer& out_buffer, 

            functor_manager_operation_type op)

        {

          switch (op) {

          case clone_functor_tag: 

            out_buffer.obj_ptr = in_buffer.obj_ptr;

            return;

          case destroy_functor_tag:

            out_buffer.obj_ptr = 0;

            return;

          case check_functor_type_tag:

            {

              // DPG TBD: Since we're only storing a pointer, it's

              // possible that the user could ask for a base class or

              // derived class. Is that okay?

              const std::type_info& check_type = 

                *static_cast<const std::type_info*>(out_buffer.const_obj_ptr);

              if (BOOST_FUNCTION_COMPARE_TYPE_ID(check_type, typeid(F)))

                out_buffer.obj_ptr = in_buffer.obj_ptr;

              else

                out_buffer.obj_ptr = 0;

            }

            return;

          case get_functor_type_tag:

            out_buffer.const_obj_ptr = &typeid(F);

            return;

          }

        }

      };

      /**

       * Determine if boost::function can use the small-object

       * optimization with the function object type F.

       */

      template<typename F>

      struct function_allows_small_object_optimization

      {

        BOOST_STATIC_CONSTANT

          (bool, 

           value = ((sizeof(F) <= sizeof(function_buffer) &&

                     (alignment_of<function_buffer>::value 

                      % alignment_of<F>::value == 0))));

      };

      /**

       * The functor_manager class contains a static function "manage" which

       * can clone or destroy the given function/function object pointer.

       */

      template<typename Functor, typename Allocator>

      struct functor_manager

      {

      private:

        typedef Functor functor_type;

        // For function pointers, the manager is trivial

        static inline void

        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 

                functor_manager_operation_type op, function_ptr_tag)

        {

          if (op == clone_functor_tag)

            out_buffer.func_ptr = in_buffer.func_ptr;

          else if (op == destroy_functor_tag)

            out_buffer.func_ptr = 0;

          else /* op == check_functor_type_tag */ {

            const std::type_info& check_type = 

              *static_cast<const std::type_info*>(out_buffer.const_obj_ptr);

            if (BOOST_FUNCTION_COMPARE_TYPE_ID(check_type, typeid(Functor)))

              out_buffer.obj_ptr = &in_buffer.func_ptr;

            else

              out_buffer.obj_ptr = 0;

          }

        }

        // Function objects that fit in the small-object buffer.

        static inline void

        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 

                functor_manager_operation_type op, mpl::true_)

        {

          if (op == clone_functor_tag) {

            const functor_type* in_functor = 

              reinterpret_cast<const functor_type*>(&in_buffer.data);

            new ((void*)&out_buffer.data) functor_type(*in_functor);

          } else if (op == destroy_functor_tag) {

            // Some compilers (Borland, vc6, ...) are unhappy with ~functor_type.

            reinterpret_cast<functor_type*>(&out_buffer.data)->~Functor();

          } else /* op == check_functor_type_tag */ {

            const std::type_info& check_type = 

              *static_cast<const std::type_info*>(out_buffer.const_obj_ptr);

            if (BOOST_FUNCTION_COMPARE_TYPE_ID(check_type, typeid(Functor)))

              out_buffer.obj_ptr = &in_buffer.data;

            else

              out_buffer.obj_ptr = 0;

          }

        }

        // Function objects that require heap allocation

        static inline void

        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 

                functor_manager_operation_type op, mpl::false_)

        {

#ifndef BOOST_NO_STD_ALLOCATOR

          typedef typename Allocator::template rebind<functor_type>::other

            allocator_type;

          typedef typename allocator_type::pointer pointer_type;

#else

          typedef functor_type* pointer_type;

#endif // BOOST_NO_STD_ALLOCATOR

#  ifndef BOOST_NO_STD_ALLOCATOR

          allocator_type allocator;

#  endif // BOOST_NO_STD_ALLOCATOR

          if (op == clone_functor_tag) {

            // GCC 2.95.3 gets the CV qualifiers wrong here, so we

            // can't do the static_cast that we should do.

            const functor_type* f =

              (const functor_type*)(in_buffer.obj_ptr);

            // Clone the functor

#  ifndef BOOST_NO_STD_ALLOCATOR

            pointer_type copy = allocator.allocate(1);

            allocator.construct(copy, *f);

            // Get back to the original pointer type

            functor_type* new_f = static_cast<functor_type*>(copy);

#  else

            functor_type* new_f = new functor_type(*f);

#  endif // BOOST_NO_STD_ALLOCATOR

            out_buffer.obj_ptr = new_f;

          } else if (op == destroy_functor_tag) {

            /* Cast from the void pointer to the functor pointer type */

            functor_type* f =

              static_cast<functor_type*>(out_buffer.obj_ptr);

#  ifndef BOOST_NO_STD_ALLOCATOR

            /* Cast from the functor pointer type to the allocator's pointer

               type */

            pointer_type victim = static_cast<pointer_type>(f);

            // Destroy and deallocate the functor

            allocator.destroy(victim);

            allocator.deallocate(victim, 1);

#  else

            delete f;

#  endif // BOOST_NO_STD_ALLOCATOR

            out_buffer.obj_ptr = 0;

          } else /* op == check_functor_type_tag */ {

            const std::type_info& check_type = 

              *static_cast<const std::type_info*>(out_buffer.const_obj_ptr);

            if (BOOST_FUNCTION_COMPARE_TYPE_ID(check_type, typeid(Functor)))

              out_buffer.obj_ptr = in_buffer.obj_ptr;

            else

              out_buffer.obj_ptr = 0;

          }

        }

        // For function objects, we determine whether the function

        // object can use the small-object optimization buffer or

        // whether we need to allocate it on the heap.

        static inline void

        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 

                functor_manager_operation_type op, function_obj_tag)

        {

          manager(in_buffer, out_buffer, op,

                  mpl::bool_<(function_allows_small_object_optimization<functor_type>::value)>());

        }

      public:

        /* Dispatch to an appropriate manager based on whether we have a

           function pointer or a function object pointer. */

        static inline void

        manage(const function_buffer& in_buffer, function_buffer& out_buffer, 

               functor_manager_operation_type op)

        {

          typedef typename get_function_tag<functor_type>::type tag_type;

          switch (op) {

          case get_functor_type_tag:

            out_buffer.const_obj_ptr = &typeid(functor_type);

            return;

          default:

            manager(in_buffer, out_buffer, op, tag_type());

            return;

          }

        }

      };

      // A type that is only used for comparisons against zero

      struct useless_clear_type {};

#ifdef BOOST_NO_SFINAE

      // These routines perform comparisons between a Boost.Function

      // object and an arbitrary function object (when the last

      // parameter is mpl::bool_<false>) or against zero (when the

      // last parameter is mpl::bool_<true>). They are only necessary

      // for compilers that don't support SFINAE.

      template<typename Function, typename Functor>

        bool

        compare_equal(const Function& f, const Functor&, int, mpl::bool_<true>)

        { return f.empty(); }

      template<typename Function, typename Functor>

        bool

        compare_not_equal(const Function& f, const Functor&, int,

                          mpl::bool_<true>)

        { return !f.empty(); }

      template<typename Function, typename Functor>

        bool

        compare_equal(const Function& f, const Functor& g, long,

                      mpl::bool_<false>)

        {

          if (const Functor* fp = f.template target<Functor>())

            return function_equal(*fp, g);

          else return false;

        }

      template<typename Function, typename Functor>

        bool

        compare_equal(const Function& f, const reference_wrapper<Functor>& g,

                      int, mpl::bool_<false>)

        {

          if (const Functor* fp = f.template target<Functor>())

            return fp == g.get_pointer();

          else return false;

        }

      template<typename Function, typename Functor>

        bool

        compare_not_equal(const Function& f, const Functor& g, long,

                          mpl::bool_<false>)

        {

          if (const Functor* fp = f.template target<Functor>())

            return !function_equal(*fp, g);

          else return true;

        }

      template<typename Function, typename Functor>

        bool

        compare_not_equal(const Function& f,

                          const reference_wrapper<Functor>& g, int,

                          mpl::bool_<false>)

        {

          if (const Functor* fp = f.template target<Functor>())

            return fp != g.get_pointer();

          else return true;

        }

#endif // BOOST_NO_SFINAE

      /**

       * Stores the "manager" portion of the vtable for a

       * boost::function object.

       */

      struct vtable_base

      {

        vtable_base() : manager(0) { }

        void (*manager)(const function_buffer& in_buffer, 

                        function_buffer& out_buffer, 

                        functor_manager_operation_type op);

      };

    } // end namespace function

  } // end namespace detail

/**

 * The function_base class contains the basic elements needed for the

 * function1, function2, function3, etc. classes. It is common to all

 * functions (and as such can be used to tell if we have one of the

 * functionN objects).

 */

class function_base

{

public:

  function_base() : vtable(0) { }

  /** Determine if the function is empty (i.e., has no target). */

  bool empty() const { return !vtable; }

  /** Retrieve the type of the stored function object, or typeid(void)

      if this is empty. */

  const std::type_info& target_type() const

  {

    if (!vtable) return typeid(void);

    detail::function::function_buffer type;

    vtable->manager(functor, type, detail::function::get_functor_type_tag);

    return *static_cast<const std::type_info*>(type.const_obj_ptr);

  }

  template<typename Functor>

    Functor* target()

    {

      if (!vtable) return 0;

      detail::function::function_buffer type_result;

      type_result.const_obj_ptr = &typeid(Functor);

      vtable->manager(functor, type_result, 

                      detail::function::check_functor_type_tag);

      return static_cast<Functor*>(type_result.obj_ptr);

    }

  template<typename Functor>

#if defined(BOOST_MSVC) && BOOST_WORKAROUND(BOOST_MSVC, < 1300)

    const Functor* target( Functor * = 0 ) const

#else

    const Functor* target() const

#endif

    {

      if (!vtable) return 0;

      detail::function::function_buffer type_result;

      type_result.const_obj_ptr = &typeid(Functor);

      vtable->manager(functor, type_result, 

                      detail::function::check_functor_type_tag);

      // GCC 2.95.3 gets the CV qualifiers wrong here, so we

      // can't do the static_cast that we should do.

      return (const Functor*)(type_result.obj_ptr);

    }

  template<typename F>

    bool contains(const F& f) const

    {

#if defined(BOOST_MSVC) && BOOST_WORKAROUND(BOOST_MSVC, < 1300)

      if (const F* fp = this->target( (F*)0 ))

#else

      if (const F* fp = this->template target<F>())

#endif