summaryrefslogtreecommitdiffhomepage
path: root/include/unicode/iso.h
blob: 1f5f0077c1e81f3403e45ba84e4a4a9f89c73e23 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
#pragma once

#include "types.h"

#include <algorithm>
#include <stdexcept>
#include <string>
#include <unordered_map>

namespace unicode::detail {

 using namespace std::string_literals;

 typedef std::unordered_map<iso_t, char32_t> iso_map_type;
 typedef std::unordered_map<char32_t, iso_t> iso_map_type_reverse;

 // ISO-8859-1 is lower 8-bit of Unicode, so no exceptions necessary
 static inline iso_map_type iso_8859_1_map;

 // ISO-8859-15 is lower 8-bit of Unicode, except for:
 static inline iso_map_type iso_8859_15_map {
  { '\xA4', U'\u20AC' }, // €
  { '\xA6', U'\u0160' }, // Š
  { '\xA8', U'\u0161' }, // š
  { '\xB4', U'\u017D' }, // Ž
  { '\xB8', U'\u017E' }, // ž
  { '\xBC', U'\u0152' }, // Œ
  { '\xBD', U'\u0153' }, // œ
  { '\xBE', U'\u0178' }, // Ÿ
 };

 inline iso_map_type_reverse reverse_iso_map(const iso_map_type& map) {
  iso_map_type_reverse result;
  std::for_each(map.cbegin(), map.cend(),
                [&](const iso_map_type::value_type& pair)
                 {
                  result.emplace(pair.second, pair.first);
                  result.emplace(static_cast<char32_t>(static_cast<uint8_t>(pair.first)), 0); // map invalid characters to a known non-mapped value as marker
                 });
  return result;
 }

 static inline iso_map_type_reverse iso_8859_15_map_reverse { reverse_iso_map(iso_8859_15_map) };
 static inline iso_map_type_reverse iso_8859_1_map_reverse { reverse_iso_map(iso_8859_1_map) };

 template<unicode::detail::iso_map_type& Map=iso_8859_1_map, typename Container=std::basic_string<iso_t>>
 struct iso_iterator {
  typedef iso_t value_type;
  typedef char32_t internal_type;
  typedef char32_t& reference;
  typedef char32_t* pointer;
  typedef size_t difference_type;
  typedef std::input_iterator_tag iterator_category;
  typedef typename Container::const_iterator iterator;
  typedef Container string_type;

  iso_iterator(const iterator& it): m_it(it) {}

  // pre-increment
  iso_iterator& operator++()
  {
   ++m_it;
   return *this;
  }

  bool operator!=(const iso_iterator& other) const
  {
   return m_it != other.m_it;
  }

  // return reference?
  internal_type operator*() const
  {
   value_type value{*m_it};

   if constexpr(std::addressof(Map) != std::addressof(iso_8859_1_map)) // mapping of 128 <= x <= 255 if needed
   {
    auto it{Map.find(value)};
    if (it != Map.end())
     return it->second;
   }
   return static_cast<internal_type>(static_cast<uint8_t>(value));
  }

  iso_iterator& operator+=(size_t distance)
  {
   std::advance(m_it, distance);
   return *this;
  }

  difference_type operator-(const iso_iterator& other) const
  {
   return m_it - other.m_it;
  }

 private:
  iterator m_it;
 };

 template<unicode::detail::iso_map_type_reverse& Map=iso_8859_1_map_reverse, typename Container=std::basic_string<iso_t>>
 struct iso_back_insert_iterator {
  typedef iso_back_insert_iterator& reference;
  typedef iso_back_insert_iterator* pointer;
  typedef size_t difference_type;
  typedef iso_t value_type;
  typedef char32_t internal_type;
  typedef std::output_iterator_tag iterator_category;
  typedef Container string_type;
  
  iso_back_insert_iterator(string_type& s): s(s) {}

  iso_back_insert_iterator& operator=(const iso_back_insert_iterator& other)
  {
   if (std::addressof(other.s) != std::addressof(s))
    throw std::runtime_error("iso_back_insert_iterator assignment operator actually called! Iterator should not be assigned to.");

   return *this;
  }

  // no-op
  reference operator++()
  {
   return *this;
  }

  // support *x = value, together with operator=()
  reference operator*()
  {
   return *this;
  }

  reference operator=(const internal_type& value)
  {
   if constexpr(std::addressof(Map) != std::addressof(iso_8859_1_map_reverse)) // mapping back to 128 <= x <= 255 if needed
   {
    auto it{Map.find(value)};
    if (it != Map.end()) {
     if (it->second == 0) // marker for non-mappable character found
      throw std::invalid_argument("Bad Unicode value to map to ISO 8859-15: "s + std::to_string(static_cast<uint32_t>(value)));
     s.push_back(it->second);
     return *this;
    }
   }

   if (value > 255)
    throw std::invalid_argument("Bad ISO 8859 value above 255: "s + std::to_string(static_cast<uint32_t>(value)));

   s.push_back(static_cast<typename iso_back_insert_iterator::value_type>(value));
   return *this;
  }

 private:
  typename iso_back_insert_iterator::string_type& s;
 };

} // namespace unicode::detail

namespace unicode {

 using namespace detail;

 // Encoding for convert() and ISO-8859-*
 template<typename InputIt, typename OutputIt>
 struct ISO_8859
 {
  typedef iso_t value_type;
  typedef typename InputIt::string_type string_type;

  static InputIt begin(const typename InputIt::string_type& s)
  {
   return InputIt(s.cbegin());
  }

  static InputIt end(const typename InputIt::string_type& s)
  {
   return InputIt(s.cend());
  }

  static OutputIt back_inserter(typename OutputIt::string_type& s)
  {
   return OutputIt(s);
  }
 };

 // Encoding for convert()
 typedef ISO_8859<iso_iterator<>, iso_back_insert_iterator<>> ISO_8859_1;
 typedef ISO_8859<iso_iterator<iso_8859_15_map>, iso_back_insert_iterator<iso_8859_15_map_reverse>> ISO_8859_15;

} // namespace unicode