Fabio
c36510c21e
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44 lines
1.3 KiB
C++
44 lines
1.3 KiB
C++
#pragma once
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#include <cstddef>
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#include <stdexcept>
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#include <string>
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#include <string_view>
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namespace engine::text {
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inline bool is_utf8_continuation(unsigned char ch) noexcept {
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return (ch & 0xC0U) == 0x80U;
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}
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inline size_t utf8_codepoint_count(std::string_view text, std::string_view label) {
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size_t count = 0;
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for (size_t pos = 0; pos < text.size();) {
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const auto ch = static_cast<unsigned char>(text[pos]);
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size_t width = 0;
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if (ch <= 0x7FU) {
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width = 1;
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} else if ((ch & 0xE0U) == 0xC0U) {
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width = 2;
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} else if ((ch & 0xF0U) == 0xE0U) {
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width = 3;
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} else if ((ch & 0xF8U) == 0xF0U) {
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width = 4;
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} else {
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throw std::runtime_error(std::string(label) + " contains invalid UTF-8");
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}
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if (pos + width > text.size()) {
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throw std::runtime_error(std::string(label) + " contains truncated UTF-8");
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}
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for (size_t i = 1; i < width; ++i) {
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if (!is_utf8_continuation(static_cast<unsigned char>(text[pos + i]))) {
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throw std::runtime_error(std::string(label) + " contains invalid UTF-8 continuation byte");
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}
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}
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pos += width;
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++count;
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}
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return count;
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}
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} // namespace engine::text
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