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fixed_string.hpp
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#ifndef CTLL__FIXED_STRING__GPP
#define CTLL__FIXED_STRING__GPP
#include <utility>
#include <cstddef>
#include <string_view>
#include <cstdint>
#include "utilities.hpp"
namespace ctll {
struct length_value_t {
uint32_t value;
uint8_t length;
};
constexpr length_value_t length_and_value_of_utf8_code_point(uint8_t first_unit) noexcept {
if ((first_unit & 0b1000'0000) == 0b0000'0000) return {static_cast<uint32_t>(first_unit), 1};
else if ((first_unit & 0b1110'0000) == 0b1100'0000) return {static_cast<uint32_t>(first_unit & 0b0001'1111), 2};
else if ((first_unit & 0b1111'0000) == 0b1110'0000) return {static_cast<uint32_t>(first_unit & 0b0000'1111), 3};
else if ((first_unit & 0b1111'1000) == 0b1111'0000) return {static_cast<uint32_t>(first_unit & 0b0000'0111), 4};
else if ((first_unit & 0b1111'1100) == 0b1111'1000) return {static_cast<uint32_t>(first_unit & 0b0000'0011), 5};
else if ((first_unit & 0b1111'1100) == 0b1111'1100) return {static_cast<uint32_t>(first_unit & 0b0000'0001), 6};
else return {0, 0};
}
constexpr char32_t value_of_trailing_utf8_code_point(uint8_t unit, bool & correct) noexcept {
if ((unit & 0b1100'0000) == 0b1000'0000) return unit & 0b0011'1111;
else {
correct = false;
return 0;
}
}
constexpr length_value_t length_and_value_of_utf16_code_point(uint16_t first_unit) noexcept {
if ((first_unit & 0b1111110000000000) == 0b1101'1000'0000'0000) return {static_cast<uint32_t>(first_unit & 0b0000001111111111), 2};
else return {first_unit, 1};
}
template <size_t N> struct fixed_string {
char32_t content[N] = {};
size_t real_size{0};
bool correct_flag{true};
template <typename T> constexpr fixed_string(const T (&input)[N+1]) noexcept {
if constexpr (std::is_same_v<T, char>) {
#ifdef CTRE_STRING_IS_UTF8
size_t out{0};
for (size_t i{0}; i < N; ++i) {
if ((i == (N-1)) && (input[i] == 0)) break;
length_value_t info = length_and_value_of_utf8_code_point(input[i]);
switch (info.length) {
case 6:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 5:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 4:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 3:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 2:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 1:
content[out++] = static_cast<char32_t>(info.value);
real_size++;
break;
default:
correct_flag = false;
return;
}
}
#else
for (size_t i{0}; i < N; ++i) {
content[i] = static_cast<uint8_t>(input[i]);
if ((i == (N-1)) && (input[i] == 0)) break;
real_size++;
}
#endif
#if __cpp_char8_t
} else if constexpr (std::is_same_v<T, char8_t>) {
size_t out{0};
for (size_t i{0}; i < N; ++i) {
if ((i == (N-1)) && (input[i] == 0)) break;
length_value_t info = length_and_value_of_utf8_code_point(input[i]);
switch (info.length) {
case 6:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 5:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 4:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 3:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 2:
if (++i < N) info.value = (info.value << 6) | value_of_trailing_utf8_code_point(input[i], correct_flag);
[[fallthrough]];
case 1:
content[out++] = static_cast<char32_t>(info.value);
real_size++;
break;
default:
correct_flag = false;
return;
}
}
#endif
} else if constexpr (std::is_same_v<T, char16_t>) {
size_t out{0};
for (size_t i{0}; i < N; ++i) {
length_value_t info = length_and_value_of_utf16_code_point(input[i]);
if (info.length == 2) {
if (++i < N) {
if ((input[i] & 0b1111'1100'0000'0000) == 0b1101'1100'0000'0000) {
content[out++] = ((info.value << 10) | (input[i] & 0b0000'0011'1111'1111)) + 0x10000;
} else {
correct_flag = false;
break;
}
}
} else {
if ((i == (N-1)) && (input[i] == 0)) break;
content[out++] = info.value;
}
}
real_size = out;
#ifndef CTLL_NO_WCHAR_T
} else if constexpr (std::is_same_v<T, wchar_t> || std::is_same_v<T, char32_t>) {
for (size_t i{0}; i < N; ++i) {
content[i] = static_cast<char32_t>(input[i]);
if ((i == (N - 1)) && (input[i] == 0)) break;
real_size++;
}
#endif
}
}
constexpr fixed_string(const fixed_string & other) noexcept {
for (size_t i{0}; i < N; ++i) {
content[i] = other.content[i];
}
real_size = other.real_size;
correct_flag = other.correct_flag;
}
constexpr bool correct() const noexcept {
return correct_flag;
}
constexpr size_t size() const noexcept {
return real_size;
}
constexpr const char32_t * begin() const noexcept {
return content;
}
constexpr const char32_t * end() const noexcept {
return content + size();
}
constexpr char32_t operator[](size_t i) const noexcept {
return content[i];
}
template <size_t M> constexpr bool is_same_as(const fixed_string<M> & rhs) const noexcept {
if (real_size != rhs.size()) return false;
for (size_t i{0}; i != real_size; ++i) {
if (content[i] != rhs[i]) return false;
}
return true;
}
constexpr operator std::basic_string_view<char32_t>() const noexcept {
return std::basic_string_view<char32_t>{content, size()};
}
};
template <> class fixed_string<0> {
static constexpr char32_t empty[1] = {0};
public:
template <typename T> constexpr fixed_string(const T *) noexcept {
}
constexpr fixed_string(std::initializer_list<char32_t>) noexcept {
}
constexpr fixed_string(const fixed_string &) noexcept {
}
constexpr bool correct() const noexcept {
return true;
}
constexpr size_t size() const noexcept {
return 0;
}
constexpr const char32_t * begin() const noexcept {
return empty;
}
constexpr const char32_t * end() const noexcept {
return empty + size();
}
constexpr char32_t operator[](size_t) const noexcept {
return 0;
}
constexpr operator std::basic_string_view<char32_t>() const noexcept {
return std::basic_string_view<char32_t>{empty, 0};
}
};
template <typename CharT, size_t N> fixed_string(const CharT (&)[N]) -> fixed_string<N-1>;
template <size_t N> fixed_string(fixed_string<N>) -> fixed_string<N>;
}
#endif