src/ipc/mem/FlexibleArray.h

   1 /*
   2  * Copyright (C) 1996-2015 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_IPC_MEM_FLEXIBLE_ARRAY_H
  10 #define SQUID_IPC_MEM_FLEXIBLE_ARRAY_H
  11
  12 // sometimes required for placement-new operator to be declared
  13 #include <new>
  14
  15 namespace Ipc
  16 {
  17
  18 namespace Mem
  19 {
  20
  21 /// A "flexible array" of Items inside some shared memory space.
  22 /// A portable equivalent of a "Item items[];" data member.
  23 /// Some compilers such as Clang can only handle flexible arrays of PODs,
  24 /// and the current C++ standard does not allow flexible arrays at all.
  25 template <class Item>
  26 class FlexibleArray
  27 {
  28 public:
  29     explicit FlexibleArray(const int capacity) {
  30         if (capacity > 1) // the first item is initialized automatically
  31             new (items+1) Item[capacity-1];
  32     }
  33
  34     Item &operator [](const int idx) { return items[idx]; }
  35     const Item &operator [](const int idx) const { return items[idx]; }
  36
  37     //const Item *operator ()() const { return items; }
  38     //Item *operator ()() { return items; }
  39
  40     Item *raw() { return items; }
  41
  42 private:
  43     Item items[1]; // ensures proper alignment of array elements
  44 };
  45
  46 } // namespace Mem
  47
  48 } // namespace Ipc
  49
  50 #endif /* SQUID_IPC_MEM_FLEXIBLE_ARRAY_H */
  51