mirror of
https://github.com/OpenMW/openmw.git
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308 lines
9.4 KiB
C++
308 lines
9.4 KiB
C++
#pragma once
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#include <sol/string_view.hpp>
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#include <array>
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#include <cstring>
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namespace sol {
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// Everything here was lifted pretty much straight out of
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// ogonek, because fuck figuring it out=
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namespace unicode {
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enum class error_code {
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ok = 0,
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invalid_code_point,
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invalid_code_unit,
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invalid_leading_surrogate,
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invalid_trailing_surrogate,
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sequence_too_short,
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overlong_sequence,
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};
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inline const string_view& to_string(error_code ec) {
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static const string_view storage[7] = { "ok",
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"invalid code points",
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"invalid code unit",
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"invalid leading surrogate",
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"invalid trailing surrogate",
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"sequence too short",
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"overlong sequence" };
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return storage[static_cast<std::size_t>(ec)];
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}
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template <typename It>
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struct decoded_result {
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error_code error;
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char32_t codepoint;
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It next;
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};
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template <typename C>
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struct encoded_result {
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error_code error;
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std::size_t code_units_size;
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std::array<C, 4> code_units;
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};
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struct unicode_detail {
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// codepoint related
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static constexpr char32_t last_code_point = 0x10FFFF;
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static constexpr char32_t first_lead_surrogate = 0xD800;
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static constexpr char32_t last_lead_surrogate = 0xDBFF;
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static constexpr char32_t first_trail_surrogate = 0xDC00;
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static constexpr char32_t last_trail_surrogate = 0xDFFF;
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static constexpr char32_t first_surrogate = first_lead_surrogate;
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static constexpr char32_t last_surrogate = last_trail_surrogate;
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static constexpr bool is_lead_surrogate(char32_t u) {
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return u >= first_lead_surrogate && u <= last_lead_surrogate;
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}
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static constexpr bool is_trail_surrogate(char32_t u) {
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return u >= first_trail_surrogate && u <= last_trail_surrogate;
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}
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static constexpr bool is_surrogate(char32_t u) {
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return u >= first_surrogate && u <= last_surrogate;
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}
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// utf8 related
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static constexpr auto last_1byte_value = 0x7Fu;
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static constexpr auto last_2byte_value = 0x7FFu;
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static constexpr auto last_3byte_value = 0xFFFFu;
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static constexpr auto start_2byte_mask = 0x80u;
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static constexpr auto start_3byte_mask = 0xE0u;
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static constexpr auto start_4byte_mask = 0xF0u;
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static constexpr auto continuation_mask = 0xC0u;
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static constexpr auto continuation_signature = 0x80u;
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static constexpr bool is_invalid(unsigned char b) {
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return b == 0xC0 || b == 0xC1 || b > 0xF4;
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}
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static constexpr bool is_continuation(unsigned char b) {
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return (b & unicode_detail::continuation_mask) == unicode_detail::continuation_signature;
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}
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static constexpr bool is_overlong(char32_t u, std::size_t bytes) {
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return u <= unicode_detail::last_1byte_value || (u <= unicode_detail::last_2byte_value && bytes > 2)
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|| (u <= unicode_detail::last_3byte_value && bytes > 3);
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}
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static constexpr int sequence_length(unsigned char b) {
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return (b & start_2byte_mask) == 0 ? 1
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: (b & start_3byte_mask) != start_3byte_mask ? 2
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: (b & start_4byte_mask) != start_4byte_mask ? 3
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: 4;
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}
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static constexpr char32_t decode(unsigned char b0, unsigned char b1) {
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return (static_cast<char32_t>((b0 & 0x1Fu) << 6u) | static_cast<char32_t>(b1 & 0x3Fu));
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}
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static constexpr char32_t decode(unsigned char b0, unsigned char b1, unsigned char b2) {
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return static_cast<char32_t>((b0 & 0x0Fu) << 12u) | static_cast<char32_t>((b1 & 0x3Fu) << 6u) | static_cast<char32_t>(b2 & 0x3Fu);
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}
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static constexpr char32_t decode(unsigned char b0, unsigned char b1, unsigned char b2, unsigned char b3) {
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return static_cast<char32_t>(static_cast<char32_t>((b0 & 0x07u) << 18u) | static_cast<char32_t>((b1 & 0x3F) << 12)
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| static_cast<char32_t>((b2 & 0x3Fu) << 6u) | static_cast<char32_t>(b3 & 0x3Fu));
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}
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// utf16 related
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static constexpr char32_t last_bmp_value = 0xFFFF;
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static constexpr char32_t normalizing_value = 0x10000;
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static constexpr int lead_surrogate_bitmask = 0xFFC00;
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static constexpr int trail_surrogate_bitmask = 0x3FF;
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static constexpr int lead_shifted_bits = 10;
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static constexpr char32_t replacement = 0xFFFD;
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static char32_t combine_surrogates(char16_t lead, char16_t trail) {
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auto hi = lead - first_lead_surrogate;
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auto lo = trail - first_trail_surrogate;
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return normalizing_value + ((hi << lead_shifted_bits) | lo);
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}
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};
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inline encoded_result<char> code_point_to_utf8(char32_t codepoint) {
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encoded_result<char> er;
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er.error = error_code::ok;
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if (codepoint <= unicode_detail::last_1byte_value) {
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er.code_units_size = 1;
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er.code_units = std::array<char, 4> { { static_cast<char>(codepoint) } };
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}
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else if (codepoint <= unicode_detail::last_2byte_value) {
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er.code_units_size = 2;
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er.code_units = std::array<char, 4> { {
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static_cast<char>(0xC0 | ((codepoint & 0x7C0) >> 6)),
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static_cast<char>(0x80 | (codepoint & 0x3F)),
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} };
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}
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else if (codepoint <= unicode_detail::last_3byte_value) {
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er.code_units_size = 3;
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er.code_units = std::array<char, 4> { {
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static_cast<char>(0xE0 | ((codepoint & 0xF000) >> 12)),
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static_cast<char>(0x80 | ((codepoint & 0xFC0) >> 6)),
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static_cast<char>(0x80 | (codepoint & 0x3F)),
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} };
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}
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else {
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er.code_units_size = 4;
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er.code_units = std::array<char, 4> { {
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static_cast<char>(0xF0 | ((codepoint & 0x1C0000) >> 18)),
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static_cast<char>(0x80 | ((codepoint & 0x3F000) >> 12)),
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static_cast<char>(0x80 | ((codepoint & 0xFC0) >> 6)),
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static_cast<char>(0x80 | (codepoint & 0x3F)),
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} };
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}
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return er;
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}
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inline encoded_result<char16_t> code_point_to_utf16(char32_t codepoint) {
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encoded_result<char16_t> er;
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if (codepoint <= unicode_detail::last_bmp_value) {
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er.code_units_size = 1;
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er.code_units = std::array<char16_t, 4> { { static_cast<char16_t>(codepoint) } };
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er.error = error_code::ok;
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}
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else {
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auto normal = codepoint - unicode_detail::normalizing_value;
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auto lead = unicode_detail::first_lead_surrogate + ((normal & unicode_detail::lead_surrogate_bitmask) >> unicode_detail::lead_shifted_bits);
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auto trail = unicode_detail::first_trail_surrogate + (normal & unicode_detail::trail_surrogate_bitmask);
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er.code_units = std::array<char16_t, 4> { { static_cast<char16_t>(lead), static_cast<char16_t>(trail) } };
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er.code_units_size = 2;
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er.error = error_code::ok;
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}
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return er;
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}
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inline encoded_result<char32_t> code_point_to_utf32(char32_t codepoint) {
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encoded_result<char32_t> er;
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er.code_units_size = 1;
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er.code_units[0] = codepoint;
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er.error = error_code::ok;
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return er;
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}
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template <typename It>
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inline decoded_result<It> utf8_to_code_point(It it, It last) {
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decoded_result<It> dr;
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if (it == last) {
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dr.next = it;
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dr.error = error_code::sequence_too_short;
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return dr;
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}
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unsigned char b0 = static_cast<unsigned char>(*it);
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std::size_t length = static_cast<std::size_t>(unicode_detail::sequence_length(b0));
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if (length == 1) {
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dr.codepoint = static_cast<char32_t>(b0);
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dr.error = error_code::ok;
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++it;
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dr.next = it;
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return dr;
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}
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if (unicode_detail::is_invalid(b0) || unicode_detail::is_continuation(b0)) {
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dr.error = error_code::invalid_code_unit;
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dr.next = it;
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return dr;
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}
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++it;
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std::array<unsigned char, 4> b;
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b[0] = b0;
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for (std::size_t i = 1; i < length; ++i) {
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b[i] = static_cast<unsigned char>(*it);
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if (!unicode_detail::is_continuation(b[i])) {
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dr.error = error_code::invalid_code_unit;
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dr.next = it;
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return dr;
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}
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++it;
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}
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char32_t decoded;
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switch (length) {
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case 2:
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decoded = unicode_detail::decode(b[0], b[1]);
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break;
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case 3:
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decoded = unicode_detail::decode(b[0], b[1], b[2]);
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break;
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default:
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decoded = unicode_detail::decode(b[0], b[1], b[2], b[3]);
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break;
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}
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if (unicode_detail::is_overlong(decoded, length)) {
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dr.error = error_code::overlong_sequence;
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return dr;
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}
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if (unicode_detail::is_surrogate(decoded) || decoded > unicode_detail::last_code_point) {
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dr.error = error_code::invalid_code_point;
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return dr;
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}
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// then everything is fine
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dr.codepoint = decoded;
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dr.error = error_code::ok;
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dr.next = it;
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return dr;
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}
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template <typename It>
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inline decoded_result<It> utf16_to_code_point(It it, It last) {
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decoded_result<It> dr;
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if (it == last) {
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dr.next = it;
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dr.error = error_code::sequence_too_short;
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return dr;
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}
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char16_t lead = static_cast<char16_t>(*it);
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if (!unicode_detail::is_surrogate(lead)) {
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++it;
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dr.codepoint = static_cast<char32_t>(lead);
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dr.next = it;
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dr.error = error_code::ok;
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return dr;
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}
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if (!unicode_detail::is_lead_surrogate(lead)) {
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dr.error = error_code::invalid_leading_surrogate;
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dr.next = it;
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return dr;
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}
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++it;
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auto trail = *it;
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if (!unicode_detail::is_trail_surrogate(trail)) {
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dr.error = error_code::invalid_trailing_surrogate;
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dr.next = it;
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return dr;
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}
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dr.codepoint = unicode_detail::combine_surrogates(lead, trail);
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dr.next = ++it;
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dr.error = error_code::ok;
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return dr;
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}
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template <typename It>
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inline decoded_result<It> utf32_to_code_point(It it, It last) {
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decoded_result<It> dr;
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if (it == last) {
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dr.next = it;
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dr.error = error_code::sequence_too_short;
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return dr;
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}
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dr.codepoint = static_cast<char32_t>(*it);
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dr.next = ++it;
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dr.error = error_code::ok;
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return dr;
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}
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} // namespace unicode
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} // namespace sol
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