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  1.  
  2. template <typename InputIterator>
  3. char32_t next_codepoint(InputIterator first, InputIterator last) {
  4.     std::array<char,4> units;
  5.     int i = 0;
  6.     assert(first != last); // replace with an actual throw if you want
  7.     while(should_read_one_more(*first)) {
  8.         units[i++] = *first;
  9.         ++first;
  10.         assert(first != last);
  11.     }
  12.     return codepoint_from(units);
  13. }
  14.  
  15. class istream_unicode_iterator
  16. : boost::iterator_facade<
  17.     istream_unicode_iterator,
  18.     char32_t,
  19.     std::input_iterator_tag> {
  20.     istream_unicode_iterator() = default;
  21.     istream_unicode_iterator(std::istream& is) : is(&is) {
  22.         ++*this;
  23.     }
  24.  
  25.     char32_t const& dereference() const {
  26.         return codepoint;
  27.     }
  28.  
  29.     void increment() {
  30.         if(*is) {
  31.             codepoint = next_codepoint(std::istream_iterator{*is}, std::istream_iterator{});
  32.         } else {
  33.             is = nullptr;
  34.         }
  35.     }
  36.  
  37.     bool equal(istream_unicode_iterator const& that) const {
  38.         return is == nullptr && that.is == nullptr;
  39.     }
  40.  
  41. private:
  42.     std::istream* is = nullptr;
  43.     char32_t codepoint;
  44. };
  45.  
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https://ideone.com/ej8Ix
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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