degski / podder

A std::vector-like type for pods with std::realloc and small vector optimization under the hood, C++17.

podder

A Vector for Pod's

• WIP

• Extended std::vector-like API, f.e. value_type pop_back_get ( ) and some 'unsafe' stuff, likely to be frowned upon, but they save cycles, we take the learning wheels of now;

• Excellent inter-operability with the STL, efficient construction and assignment from and comparison with all STL container types (including c-arrays);

• Custom allocation with std::realloc and friends, does not cannot support std::allocators (the main reason I started this project);

• Not any checking of any return values from std::malloc or std::realloc` is implemented, if you run out of memory, close FireFox or head of to the shop to buy some DIMM's;

• Pod's only (std::trivially_copyable);

• Implementation takes advantage of bit-fields, which is possibly non-portable (that's what the gurus keep saying), but they make for clear code and I'm convinced, nowadays, the compiler knows best;

• No macros, except for one that fixes a VC-silliness (fix on the way!), #define small char and a useful one for Clang/LLVM;

• Small Vector Optimization, small vector capacities by value_type (size_type: std::uint64_t (std::uint32_t) ):

  • std::uint8_t : 23 (15);
  • std::uint16_t: 11 ( 7);
  • std::uint32_t: 5 ( 3);
  • std::uint64_t: 2 ( 1);
  • 64b < sizeof ( value_type ) <= 128b : 1 (no SVO);
  • sizeof ( value_type ) > 128b : no SVO (no SVO);

• Small Vector Optimization Caveat: not allowed by the standard (23.2.1/p10/b6):

  "Unless otherwise specified ... no swap() function invalidates any references, pointers, or iterators referring to the elements of the containers being swapped."

  So I specify otherwise, std::swap ( value_type & a, value_type & b ) has not been overloaded and swap ( podder & a, podder & b ) lives in the pdr namespace;

• Comparision operators, also with all STL containers and c-arrays (rhs). Overload std::less<your_type> and std::greater<your_type> for your value_type, and provide an operator == ( your_class & rhs ) if non-trivial comparison is required;

• Growth policy, customizable and extendible;

• Customizable size_type, std::uint32_t or std::uint64_t;

• C++17 and moving;

• Limited to 64-bit linux and windows (for now);

• Some quick testing of emplace_back() with small vectors up to 256 values of std::uint8_t and std::uint16_t indicates a speedup of 35-40% as compared to the MSVC std::vector. I have not yet looked at things to optimize or bottle-necks, so looks promising.

• License: MIT, warranty till checkout;

podder is a header only library, with no dependencies other than the STL.