connectivity/source/drivers/postgresql/pq_allocator.hxx

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  41  *    Major Contributor(s):
  42  *    [ Copyright (C) 2011 Lionel Elie Mamane <lionel@mamane.lu> ]
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  54  ************************************************************************/
  55
  56 #ifndef _PQ_ALLOCATOR_
  57 #define _PQ_ALLOCATOR_
  58
  59 #include <cstddef>
  60 #include "sal/types.h"
  61
  62 /** jbu: This source has been copied from sal/inc/internal/allocator.hxx,
  63          because it is not a public interface. Thx a lot for figuring this
  64          out.
  65  */
  66
  67 //######################################################
  68 // This is no general purpose STL allocator but one
  69 // necessary to use STL for some implementation but
  70 // avoid linking sal against the STLPort library!!!
  71 // For more information on when and how to define a
  72 // custom stl allocator have a look at Scott Meyers:
  73 // "Effective STL", Nicolai M. Josuttis:
  74 // "The C++ Standard Library - A Tutorial and Reference"
  75 // and at http://www.josuttis.com/cppcode/allocator.html
  76
  77 namespace pq_sdbc_driver {
  78
  79 template<class T>
  80 class Allocator
  81 {
  82 public:
  83     typedef T value_type;
  84     typedef T* pointer;
  85     typedef const T* const_pointer;
  86     typedef T& reference;
  87     typedef const T& const_reference;
  88     typedef ::std::size_t size_type;
  89     typedef ::std::ptrdiff_t difference_type;
  90
  91     //-----------------------------------------
  92     template<class U>
  93     struct rebind
  94     {
  95         typedef Allocator<U> other;
  96     };
  97
  98     //-----------------------------------------
  99     pointer address (reference value) const
 100     {
 101         return &value;
 102     }
 103
 104     //-----------------------------------------
 105     const_pointer address (const_reference value) const
 106     {
 107         return &value;
 108     }
 109
 110     //-----------------------------------------
 111     Allocator() SAL_THROW(())
 112     {}
 113
 114     //-----------------------------------------
 115     template<class U>
 116     Allocator (const Allocator<U>&) SAL_THROW(())
 117     {}
 118
 119     //-----------------------------------------
 120     Allocator(const Allocator&) SAL_THROW(())
 121     {}
 122
 123     //-----------------------------------------
 124     ~Allocator() SAL_THROW(())
 125     {}
 126
 127     //-----------------------------------------
 128     size_type max_size() const SAL_THROW(())
 129     {
 130         return size_type(-1)/sizeof(T);
 131     }
 132
 133     //-----------------------------------------
 134     /* Normally the code for allocate should
 135        throw a std::bad_alloc exception if the
 136        requested memory could not be allocated:
 137        (C++ standard 20.4.1.1):
 138
 139        pointer allocate (size_type n, const void* hint = 0)
 140        {
 141          pointer p = reinterpret_cast<pointer>(
 142              rtl_allocateMemory(sal_uInt32(n * sizeof(T))));
 143
 144          if (NULL == p)
 145              throw ::std::bad_alloc();
 146
 147          return p;
 148        }
 149
 150        but some compilers do not compile it if exceptions
 151        are not enabled, e.g. GCC under Linux and it is
 152        in general not desired to compile sal with exceptions
 153        enabled. */
 154     pointer allocate (size_type n, SAL_UNUSED_PARAMETER const void* = 0)
 155     {
 156         return reinterpret_cast<pointer>(
 157             rtl_allocateMemory(sal_uInt32(n * sizeof(T))));
 158     }
 159
 160     //-----------------------------------------
 161     void deallocate (pointer p, SAL_UNUSED_PARAMETER size_type)
 162     {
 163         rtl_freeMemory(p);
 164     }
 165
 166     //-----------------------------------------
 167     void construct (pointer p, const T& value)
 168     {
 169         new ((void*)p)T(value);
 170     }
 171
 172     // LEM: GNU libstdc++ vectors expect this one to exist,
 173     // at least if one intends to create vectors by giving
 174     // only a size and no initialising value.
 175     //-----------------------------------------
 176     void construct (pointer p)
 177     {
 178         new ((void*)p)T;
 179     }
 180
 181     //-----------------------------------------
 182     void destroy (pointer p)
 183     {
 184         p->~T();
 185 #ifdef _MSC_VER
 186         (void) p; // spurious warning C4100: 'p': unreferenced formal parameter
 187 #endif
 188     }
 189 };
 190
 191 //######################################################
 192 // Custom STL allocators must be stateless (see
 193 // references above) that's why the operators below
 194 // return always true or false
 195 template<class T, class U>
 196 inline bool operator== (const Allocator<T>&, const Allocator<U>&) SAL_THROW(())
 197 {
 198     return true;
 199 }
 200
 201 template<class T, class U>
 202 inline bool operator!= (const Allocator<T>&, const Allocator<U>&) SAL_THROW(())
 203 {
 204     return false;
 205 }
 206
 207 } /* namespace sal */
 208
 209 //######################################################
 210 /* REQUIRED BY STLPort (see stlport '_alloc.h'):
 211    Hack for compilers that do not support member
 212    template classes (e.g. MSVC 6) */
 213 #if defined (_MSC_VER)
 214 #if (_MSC_VER < 1400) // MSVC 6
 215 namespace _STL
 216 {
 217 #endif
 218 #endif
 219     template<class T, class U>
 220     inline pq_sdbc_driver::Allocator<U> & __stl_alloc_rebind (
 221         pq_sdbc_driver::Allocator<T> & a, U const *)
 222     {
 223         return (pq_sdbc_driver::Allocator<U>&)(a);
 224     }
 225 #if defined (_MSC_VER)
 226 #if (_MSC_VER < 1400) // MSVC 6
 227 }
 228 #endif
 229 #endif
 230
 231 #endif /* _PQ_ALLOCATOR_ */