utils/benchmark/src/arraysize.h

   1 #ifndef BENCHMARK_ARRAYSIZE_H_
   2 #define BENCHMARK_ARRAYSIZE_H_
   3
   4 #include "internal_macros.h"
   5
   6 namespace benchmark {
   7 namespace internal {
   8 // The arraysize(arr) macro returns the # of elements in an array arr.
   9 // The expression is a compile-time constant, and therefore can be
  10 // used in defining new arrays, for example.  If you use arraysize on
  11 // a pointer by mistake, you will get a compile-time error.
  12 //
  13
  14 // This template function declaration is used in defining arraysize.
  15 // Note that the function doesn't need an implementation, as we only
  16 // use its type.
  17 template <typename T, size_t N>
  18 char (&ArraySizeHelper(T (&array)[N]))[N];
  19
  20 // That gcc wants both of these prototypes seems mysterious. VC, for
  21 // its part, can't decide which to use (another mystery). Matching of
  22 // template overloads: the final frontier.
  23 #ifndef COMPILER_MSVC
  24 template <typename T, size_t N>
  25 char (&ArraySizeHelper(const T (&array)[N]))[N];
  26 #endif
  27
  28 #define arraysize(array) (sizeof(::benchmark::internal::ArraySizeHelper(array)))
  29
  30 }  // end namespace internal
  31 }  // end namespace benchmark
  32
  33 #endif  // BENCHMARK_ARRAYSIZE_H_