_tools.h

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/*
 * Copyright (c) 2003
 * Francois Dumont
 *
 * This material is provided "as is", with absolutely no warranty expressed
 * or implied. Any use is at your own risk.
 *
 * Permission to use or copy this software for any purpose is hereby granted
 * without fee, provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 *
 */

/* NOTE: This is an internal header file, included by other STL headers.
 *   You should not attempt to use it directly.
 */

#ifndef _STLP_POINTERS_SPEC_TOOLS_H
#define _STLP_POINTERS_SPEC_TOOLS_H

#ifndef _STLP_TYPE_TRAITS_H
#  include <stl/type_traits.h>
#endif

_STLP_BEGIN_NAMESPACE

//Some usefull declarations:
template <class _Tp> struct less;

_STLP_MOVE_TO_PRIV_NAMESPACE

template <class _StorageT, class _ValueT, class _BinaryPredicate>
struct _BinaryPredWrapper;

/*
 * Since the compiler only allows at most one non-trivial
 * implicit conversion we can make use of a shim class to
 * be sure that functions below doesn't accept classes with
 * implicit pointer conversion operators
 */
struct _VoidPointerShim
{ _VoidPointerShim(void*); };
struct _ConstVoidPointerShim
{ _ConstVoidPointerShim(const void*); };
struct _VolatileVoidPointerShim
{ _VolatileVoidPointerShim(volatile void*); };
struct _ConstVolatileVoidPointerShim
{ _ConstVolatileVoidPointerShim(const volatile void*); };

//The dispatch functions:
template <class _Tp>
char _UseVoidPtrStorageType(const __false_type& /*POD*/, const _Tp&);
char _UseVoidPtrStorageType(const __true_type& /*POD*/, ...);
char* _UseVoidPtrStorageType(const __true_type& /*POD*/, _VoidPointerShim);

template <class _Tp>
char _UseConstVoidPtrStorageType(const __false_type& /*POD*/, const _Tp&);
char _UseConstVoidPtrStorageType(const __true_type& /*POD*/, ...);
char* _UseConstVoidPtrStorageType(const __true_type& /*POD*/, _ConstVoidPointerShim);

template <class _Tp>
char _UseVolatileVoidPtrStorageType(const __false_type& /*POD*/, const _Tp&);
char _UseVolatileVoidPtrStorageType(const __true_type& /*POD*/, ...);
char* _UseVolatileVoidPtrStorageType(const __true_type& /*POD*/, _VolatileVoidPointerShim);

template <class _Tp>
char _UseConstVolatileVoidPtrStorageType(const __false_type& /*POD*/, const _Tp&);
char _UseConstVolatileVoidPtrStorageType(const __true_type& /*POD*/, ...);
char* _UseConstVolatileVoidPtrStorageType(const __true_type& /*POD*/, _ConstVolatileVoidPointerShim);

#if defined (_STLP_CLASS_PARTIAL_SPECIALIZATION)
/* Thanks to class partial specialization the pointer specialization feature can even be used in
 * presence of incomplete type:
 * struct MyStruct {
 *   typedef vector<MyStruct> MyStructContainer;
 *   typedef MyStructContainer::iterator MyStructIterator;
 * };
 */

template <class _Tp>
struct _StorageType {
  typedef _Tp _QualifiedType;
  typedef _Tp _Type;
  enum { use_const_volatile_void_ptr = 0 };
};

template <class _Tp>
struct _StorageType<_Tp*> {
  // Even if we detect a pointer type we use dispatch function to consider if it can be stored as a void*.
  // For instance function pointer might not necessarily be convertible to void*.
  enum { use_void_ptr = (sizeof(_UseVoidPtrStorageType(__true_type(),
                                                       __STATIC_CAST(_Tp*, 0))) == sizeof(char*)) };
  enum { use_const_volatile_void_ptr = use_void_ptr };
  typedef typename __select<use_void_ptr,
                            void*,
                            _Tp*>::_Ret _QualifiedType;
  typedef _QualifiedType _Type;
};

template <class _Tp>
struct _StorageType<_Tp const*> {
  enum { use_void_ptr = (sizeof(_UseConstVoidPtrStorageType(__true_type(),
                                                            __STATIC_CAST(const _Tp*, 0))) == sizeof(char*)) };
  enum { use_const_volatile_void_ptr = use_void_ptr };
  typedef typename __select<use_void_ptr,
                            const void*,
                            const _Tp*>::_Ret _QualifiedType;
  typedef typename __select<use_void_ptr,
                            void*,
                            const _Tp*>::_Ret _Type;
};

template <class _Tp>
struct _StorageType<_Tp volatile*> {
  enum { use_void_ptr = (sizeof(_UseVolatileVoidPtrStorageType(__true_type(),
                                                               __STATIC_CAST(_Tp volatile*, 0))) == sizeof(char*)) };
  enum { use_const_volatile_void_ptr = use_void_ptr };
  typedef typename __select<use_void_ptr,
                            volatile void*,
                            volatile _Tp*>::_Ret _QualifiedType;
  typedef typename __select<use_void_ptr,
                            void*,
                            volatile _Tp*>::_Ret _Type;
};

template <class _Tp>
struct _StorageType<_Tp const volatile*> {
  enum { use_void_ptr = (sizeof(_UseConstVolatileVoidPtrStorageType(__true_type(),
                                                                    __STATIC_CAST(_Tp const volatile*, 0))) == sizeof(char*)) };
  enum { use_const_volatile_void_ptr = use_void_ptr };
  typedef typename __select<use_void_ptr,
                            const volatile void*,
                            const volatile _Tp*>::_Ret _QualifiedType;
  typedef typename __select<use_void_ptr,
                            void*,
                            const volatile _Tp*>::_Ret _Type;
};
#else
template <class _Tp>
struct _StorageType {
  typedef typename __type_traits<_Tp>::is_POD_type _PODType;

#if !defined (__BORLANDC__) || (__BORLANDC__ != 0x560)
  static _Tp __null_rep();
#else
  static _Tp __null_rep;
#endif
  enum { use_void_ptr = (sizeof(_UseVoidPtrStorageType(_PODType(), __null_rep())) == sizeof(char*)) };
  enum { use_const_void_ptr = (sizeof(_UseConstVoidPtrStorageType(_PODType(), __null_rep())) == sizeof(char*)) };
  enum { use_volatile_void_ptr = (sizeof(_UseVolatileVoidPtrStorageType(_PODType(), __null_rep())) == sizeof(char*)) };
  enum { use_const_volatile_void_ptr = (sizeof(_UseConstVolatileVoidPtrStorageType(_PODType(), __null_rep())) == sizeof(char*)) };

  typedef typename __select<!use_const_volatile_void_ptr,
                            _Tp,
          typename __select<use_void_ptr,
                            void*,
          typename __select<use_const_void_ptr,
                            const void*,
          typename __select<use_volatile_void_ptr,
                            volatile void*,
                            const volatile void*>::_Ret >::_Ret >::_Ret >::_Ret _QualifiedType;

#if !defined (_STLP_CLASS_PARTIAL_SPECIALIZATION)
  /* If the compiler do not support the iterator_traits structure we cannot wrap
   * iterators pass to container template methods. The iterator dereferenced value
   * has to be storable without any cast in the chosen storage type. To guaranty
   * that the void pointer has to be correctly qualified.
   */
  typedef _QualifiedType _Type;
#else
  /* With iterator_traits we can wrap passed iterators and make the necessary casts.
   * We can always use a simple void* storage type:
   */
  typedef typename __select<use_const_volatile_void_ptr,
                            void*,
                            _Tp>::_Ret _Type;
#endif
};
#endif

template <class _Tp, class _Compare>
struct _AssocStorageTypes {
  typedef _StorageType<_Tp> _StorageTypeInfo;
  typedef typename _StorageTypeInfo::_Type _SType;

  //We need to also check that the comparison functor used to instanciate the assoc container
  //is the default Standard less implementation:
  enum { ptr_type = _StorageTypeInfo::use_const_volatile_void_ptr };
  typedef typename _IsSTLportClass<_Compare>::_Ret _STLportLess;
  enum { is_default_less = __type2bool<_STLportLess>::_Ret };
  typedef typename __select<is_default_less, _SType, _Tp>::_Ret _KeyStorageType;
  typedef typename __select<is_default_less && ptr_type,
                            _BinaryPredWrapper<_KeyStorageType, _Tp, _Compare>,
                            _Compare>::_Ret _CompareStorageType;
};


#if defined (_STLP_CLASS_PARTIAL_SPECIALIZATION)
/*
 * Base struct to deal with qualifiers
 */
template <class _StorageT, class _QualifiedStorageT>
struct _VoidCastTraitsAux {
  typedef _QualifiedStorageT void_cv_type;
  typedef _StorageT void_type;

  static void_type * uncv_ptr(void_cv_type *__ptr)
  { return __ptr; }
  static void_type const* uncv_cptr(void_cv_type const*__ptr)
  { return __ptr; }
  static void_type ** uncv_pptr(void_cv_type **__ptr)
  { return __ptr; }
  static void_type & uncv_ref(void_cv_type & __ref)
  { return __ref; }
  static void_type const& uncv_cref(void_cv_type const& __ref)
  { return __ref; }
  static void_cv_type* cv_ptr(void_type *__ptr)
  { return __ptr; }
  static void_cv_type const* cv_cptr(void_type const*__ptr)
  { return __ptr; }
  static void_cv_type ** cv_pptr(void_type **__ptr)
  { return __ptr; }
  static void_cv_type & cv_ref(void_type & __ref)
  { return __ref; }
  static void_cv_type const& cv_cref(void_type const& __ref)
  { return __ref; }
};

template <class _VoidCVType>
struct _VoidCastTraitsAuxBase {
  typedef _VoidCVType* void_cv_type;
  typedef void* void_type;

  static void_type* uncv_ptr(void_cv_type *__ptr)