extl/utility/element_num.h

   1 /* ///////////////////////////////////////////////////////////////////////
   2  * File:                element_num.h
   3  *
   4  * Created:             08.02.02
   5  * Updated:             08.04.14
   6  *
   7  * Brief: Gets the number of elements in the array
   8  *
   9  * [<Home>]
  10  * Copyright (c) 2008-2020, Waruqi All rights reserved.
  11  * //////////////////////////////////////////////////////////////////// */
  12 #ifndef EXTL_UTILITY_ELEMENT_NUM_H
  13 #define EXTL_UTILITY_ELEMENT_NUM_H
  14
  15 /*!\file element_num.h
  16  * \brief Gets the number of elements in the array
  17  */
  18
  19 /* ///////////////////////////////////////////////////////////////////////
  20  * Includes
  21  */
  22 #include "static_assert.h"
  23 #include "../type/typedef.h"
  24
  25 /* ///////////////////////////////////////////////////////////////////////
  26  * ::extl namespace
  27  */
  28 EXTL_BEGIN_NAMESPACE
  29
  30 /* //////////////////////////////////////////////////////////////////// */
  31 #if defined(__cplusplus) && \
  32      defined(EXTL_STATIC_ARRAY_SIZE_DETERMINATION_SUPPORT)
  33
  34 #       if defined(EXTL_COMPILER_IS_GCC)
  35
  36 #               pragma pack(push, 1)
  37                 template < e_uint_t N >
  38                 struct extl_array_size
  39                 {
  40                         e_byte_t c[N];
  41                 };
  42 #               pragma pack(pop)
  43
  44                 template < typename_param_k T, e_uint_t N >
  45                 extl_array_size<N> const& extl_static_array_size(T (&)[N]);
  46
  47                 /// EXTL_ELEMENT_NUM
  48 #               define EXTL_ELEMENT_NUM(ar)     sizeof(EXTL_NS(extl_static_array_size)(ar))
  49 #       else
  50
  51                 template < e_uint_t N >
  52                 struct extl_array_size
  53                 {
  54                         e_byte_t c[N];
  55                 };
  56
  57                 /* Passing array by reference will not cause pointer decay  */
  58                 template < typename_param_k  T, e_uint_t N >
  59                 extl_array_size<N> const& extl_static_array_size(T (&)[N]);
  60
  61                 /// EXTL_ELEMENT_NUM
  62 #               define EXTL_ELEMENT_NUM(ar)     sizeof(EXTL_NS(extl_static_array_size)(ar).c)
  63 #       endif /* EXTL_COMPILER_IS_GCC */
  64 #else
  65         /*!\brief EXTL_ELEMENT_NUM does'nt support array-to-pointer decay
  66          *
  67          * int ar[10];
  68          * int *p=ar; //or int *p=&ar[0];
  69          * EXTL_ELEMENT_NUM(ar) == 10
  70          * EXTL_ELEMENT_NUM(p)  ?= 1
  71          */
  72 #       define EXTL_ELEMENT_NUM(ar)     (sizeof(ar) / sizeof(0[(ar)]))
  73 #endif /* defined(__cplusplus) && \
  74                   defined(EXTL_STATIC_ARRAY_SIZE_DETERMINATION_SUPPORT) */
  75
  76 /* ///////////////////////////////////////////////////////////////////////
  77  * Unit-testing
  78  */
  79 #ifdef EXTL_UTILITY_ELEMENT_NUM_TEST_ENABLE
  80 #       include "unit_test/element_num_test.h"
  81 #endif
  82 /* ///////////////////////////////////////////////////////////////////////
  83  * ::extl namespace
  84  */
  85 EXTL_END_NAMESPACE
  86
  87 /* //////////////////////////////////////////////////////////////////// */
  88 #endif  /* EXTL_UTILITY_ELEMENT_NUM_H */
  89 /* //////////////////////////////////////////////////////////////////// */
  90
  91