1 files changed, 123 insertions, 0 deletions
diff --git a/include/unicode.h b/include/unicode.h
new file mode 100644
index 0000000..2969aa0
--- /dev/null
+++ b/include/unicode.h
@@ -0,0 +1,123 @@
+// libunicode
+// Copyright (C) 2021 Roland Reichwein
+
+#pragma once
+
+#include <algorithm>
+#include <string>
+
+namespace {
+
+ struct utf8_iterator
+ {
+  typedef char32_t value_type;
+  typedef char32_t& reference;
+
+  void get_value()
+  {
+   // TODO: set value to current data in *iterator ...
+   value = 'X';
+  }
+
+  size_t get_number_of_utf8_bytes()
+  {
+   // TODO: how many bytes
+   return 1;
+  }
+
+  // pre-increment
+  utf8_iterator& operator++()
+  {
+   iterator += get_number_of_utf8_bytes();
+   return *this;
+  }
+
+  bool operator!=(const utf8_iterator& other) const
+  {
+   return iterator != other.iterator;
+  }
+
+  reference operator*()
+  {
+   get_value();
+   return value;
+  }
+
+  std::u8string::iterator iterator;
+
+  std::u8string::iterator end_iterator;
+  value_type value{};
+ };
+
+ struct utf16_back_insert_iterator
+ {
+  typedef utf16_back_insert_iterator& reference;
+
+  utf16_back_insert_iterator(std::u16string& s): s(s) {}
+
+  // no-op
+  utf16_back_insert_iterator& operator++()
+  {
+   return *this;
+  }
+
+  // support *x = value, together with operator=()
+  reference operator*()
+  {
+   return *this;
+  }
+
+  // append utf-16 word sequence
+  reference operator=(const char32_t& value)
+  {
+   s.push_back(0); // TODO
+  }
+
+  std::u16string& s;
+ };
+
+ utf16_back_insert_iterator utf16_back_inserter(std::u16string& s)
+ {
+  return utf16_back_insert_iterator(s);
+ }
+
+ utf8_iterator utf8_begin(std::u8string& s)
+ {
+  return utf8_iterator{s.begin(), s.end()};
+ }
+
+ utf8_iterator utf8_end(std::u8string& s)
+ {
+  return utf8_iterator{s.end(), s.end()};
+ }
+
+} // namespace
+
+namespace unicode {
+
+// returns number of bytes in UTF-8 byte sequence of first found code point,
+// if found. 0 if none found or sequence empty.
+//size_t utf8_start()
+//{
+//}
+
+std::u16string utf8_to_utf16(const std::u8string& s)
+{
+ std::u16string result;
+
+ std::copy(utf8_begin(s), utf8_end(s), utf16_back_inserter(result));
+
+ return result;
+}
+
+//std::u8string utf16_to_utf8(const std::u16string& s)
+//{
+// std::u8string result;
+//
+// std::transform(utf16_begin(s), utf16_end(s), std::back_inserter(result));
+//
+// return result;
+//}
+
+} // namespace unicode
+