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#ifndef U16_HH
#define U16_HH
#include "u.hh" // IWYU pragma: export
#include <cstdint> // IWYU pragma: export
#include <expected>
#include <iterator>
#include <type_traits>
#include <utility>
namespace u16 {
template <std::forward_iterator T>
requires std::is_same_v<std::iter_value_t<T>, uint16_t>
std::expected<uint32_t, u::ReadError> read(T& start, T const& end) {
if (start == end)
return std::unexpected(u::ReadError::End);
uint16_t u = *start;
if (u >= 0xd800 && u <= 0xdbff) {
if (std::distance(start, end) < 2) {
return std::unexpected(u::ReadError::Incomplete);
}
std::advance(start, 1);
if (*start >= 0xdc00 && *start <= 0xdfff) {
uint16_t v = *start;
std::advance(start, 1);
return 0x10000 + (((u - 0xd800) << 10) | (v - 0xdc00));
}
return std::unexpected(u::ReadError::Invalid);
}
std::advance(start, 1);
if (u >= 0xdc00 && u <= 0xdfff) {
return std::unexpected(u::ReadError::Invalid);
}
return u;
}
template <std::forward_iterator T>
requires std::is_same_v<std::iter_value_t<T>, uint16_t>
std::expected<uint32_t, u::ReadErrorReplace> read_replace(T& start,
T const& end,
bool eof) {
auto const tmp = start;
auto ret = read(start, end);
if (ret.has_value())
return *ret;
switch (ret.error()) {
case u::ReadError::Incomplete:
if (eof)
break;
return std::unexpected(u::ReadErrorReplace::Incomplete);
case u::ReadError::End:
return std::unexpected(u::ReadErrorReplace::End);
case u::ReadError::Invalid:
break;
}
start = tmp + 1;
return 0xfffd;
}
template <std::forward_iterator T>
requires std::is_same_v<std::iter_value_t<T>, uint16_t>
bool write(T& start, T const& end, uint32_t code) {
if (code < 0x10000) {
if (start == end)
return false;
*start = static_cast<uint16_t>(code);
} else {
if (std::distance(start, end) < 2)
return false;
code -= 0x10000;
*start = static_cast<uint16_t>(0xd800 + (code >> 10));
std::advance(start, 1);
*start = static_cast<uint16_t>(0xdc00 + (code & 0x3ff));
}
std::advance(start, 1);
return true;
}
template <std::forward_iterator T>
requires std::is_same_v<std::iter_value_t<T>, uint16_t>
bool skip(T& start, T const& end) {
if (start == end)
return false;
if (*start >= 0xd800 && *start <= 0xdbff) {
if (std::distance(start, end) < 2)
return false;
std::advance(start, 2);
return true;
}
std::advance(start, 1);
return true;
}
} // namespace u16
#endif // U16_HH
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