libcxx/test/support/constexpr_char_traits.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _CONSTEXPR_CHAR_TRAITS
  11 #define _CONSTEXPR_CHAR_TRAITS
  12
  13 #include <string>
  14 #include <cassert>
  15 #include <cstddef>
  16
  17 #include "test_macros.h"
  18
  19 template <class CharT>
  20 struct constexpr_char_traits
  21 {
  22     typedef CharT     char_type;
  23     typedef int       int_type;
  24     typedef std::streamoff off_type;
  25     typedef std::streampos pos_type;
  26     typedef std::mbstate_t state_type;
  27     // The comparison_category is omitted so the class will have weak_ordering
  28     // in C++20. This is intentional.
  29
  30     static TEST_CONSTEXPR_CXX14 void assign(char_type& c1, const char_type& c2) TEST_NOEXCEPT
  31         {c1 = c2;}
  32
  33     static TEST_CONSTEXPR bool eq(char_type c1, char_type c2) TEST_NOEXCEPT
  34         {return c1 == c2;}
  35
  36     static TEST_CONSTEXPR  bool lt(char_type c1, char_type c2) TEST_NOEXCEPT
  37         {return c1 < c2;}
  38
  39     static TEST_CONSTEXPR_CXX14 int              compare(const char_type* s1, const char_type* s2, std::size_t n);
  40     static TEST_CONSTEXPR_CXX14 std::size_t           length(const char_type* s);
  41     static TEST_CONSTEXPR_CXX14 const char_type* find(const char_type* s, std::size_t n, const char_type& a);
  42     static TEST_CONSTEXPR_CXX14 char_type*       move(char_type* s1, const char_type* s2, std::size_t n);
  43     static TEST_CONSTEXPR_CXX14 char_type*       copy(char_type* s1, const char_type* s2, std::size_t n);
  44     static TEST_CONSTEXPR_CXX14 char_type*       assign(char_type* s, std::size_t n, char_type a);
  45
  46     static TEST_CONSTEXPR int_type  not_eof(int_type c) TEST_NOEXCEPT
  47         {return eq_int_type(c, eof()) ? ~eof() : c;}
  48
  49     static TEST_CONSTEXPR char_type to_char_type(int_type c) TEST_NOEXCEPT
  50         {return char_type(c);}
  51
  52     static TEST_CONSTEXPR int_type  to_int_type(char_type c) TEST_NOEXCEPT
  53         {return int_type(c);}
  54
  55     static TEST_CONSTEXPR bool      eq_int_type(int_type c1, int_type c2) TEST_NOEXCEPT
  56         {return c1 == c2;}
  57
  58     static TEST_CONSTEXPR int_type  eof() TEST_NOEXCEPT
  59         {return int_type(EOF);}
  60 };
  61
  62
  63 template <class CharT>
  64 TEST_CONSTEXPR_CXX14 int
  65 constexpr_char_traits<CharT>::compare(const char_type* s1, const char_type* s2, std::size_t n)
  66 {
  67     for (; n; --n, ++s1, ++s2)
  68     {
  69         if (lt(*s1, *s2))
  70             return -1;
  71         if (lt(*s2, *s1))
  72             return 1;
  73     }
  74     return 0;
  75 }
  76
  77 template <class CharT>
  78 TEST_CONSTEXPR_CXX14 std::size_t
  79 constexpr_char_traits<CharT>::length(const char_type* s)
  80 {
  81     std::size_t len = 0;
  82     for (; !eq(*s, char_type(0)); ++s)
  83         ++len;
  84     return len;
  85 }
  86
  87 template <class CharT>
  88 TEST_CONSTEXPR_CXX14 const CharT*
  89 constexpr_char_traits<CharT>::find(const char_type* s, std::size_t n, const char_type& a)
  90 {
  91     for (; n; --n)
  92     {
  93         if (eq(*s, a))
  94             return s;
  95         ++s;
  96     }
  97     return 0;
  98 }
  99
 100 template <class CharT>
 101 TEST_CONSTEXPR_CXX14 CharT*
 102 constexpr_char_traits<CharT>::move(char_type* s1, const char_type* s2, std::size_t n)
 103 {
 104     char_type* r = s1;
 105     if (s1 < s2)
 106     {
 107         for (; n; --n, ++s1, ++s2)
 108             assign(*s1, *s2);
 109     }
 110     else if (s2 < s1)
 111     {
 112         s1 += n;
 113         s2 += n;
 114         for (; n; --n)
 115             assign(*--s1, *--s2);
 116     }
 117     return r;
 118 }
 119
 120 template <class CharT>
 121 TEST_CONSTEXPR_CXX14 CharT*
 122 constexpr_char_traits<CharT>::copy(char_type* s1, const char_type* s2, std::size_t n)
 123 {
 124     if (!TEST_IS_CONSTANT_EVALUATED) // fails in constexpr because we might be comparing unrelated pointers
 125         assert(s2 < s1 || s2 >= s1+n);
 126     char_type* r = s1;
 127     for (; n; --n, ++s1, ++s2)
 128         assign(*s1, *s2);
 129     return r;
 130 }
 131
 132 template <class CharT>
 133 TEST_CONSTEXPR_CXX14 CharT*
 134 constexpr_char_traits<CharT>::assign(char_type* s, std::size_t n, char_type a)
 135 {
 136     char_type* r = s;
 137     for (; n; --n, ++s)
 138         assign(*s, a);
 139     return r;
 140 }
 141
 142 #endif // _CONSTEXPR_CHAR_TRAITS