Is Stephen Lavavej's Mallocator the same in C++11?

Question

8 years ago, Stephen Lavavej published this blog post containing a simple allocator implementation, named the \"Mallocator\". Since then we\'ve transitioned to the era of C++11

Answer 1

STL himself has an answer to this question in his STL Features and Implementation techniques talk at CppCon 2014 (Starting at 26'30).

The slides are on github.

I merged the content of slides 28 and 29 below:

#include  // size_t, malloc, free
#include  // bad_alloc, bad_array_new_length
template  struct Mallocator {
  typedef T value_type;
  Mallocator() noexcept { } // default ctor not required
  template  Mallocator(const Mallocator&) noexcept { }
  template  bool operator==(
    const Mallocator&) const noexcept { return true; }
  template  bool operator!=(
    const Mallocator&) const noexcept { return false; }

  T * allocate(const size_t n) const {
      if (n == 0) { return nullptr; }
      if (n > static_cast(-1) / sizeof(T)) {
          throw std::bad_array_new_length();
      }
      void * const pv = malloc(n * sizeof(T));
      if (!pv) { throw std::bad_alloc(); }
      return static_cast(pv);
  }
  void deallocate(T * const p, size_t) const noexcept {
      free(p);
  }
};

Note that it handles correctly the possible overflow in allocate.