386 lines
11 KiB
C++
386 lines
11 KiB
C++
/* String implementation details, mainly regarding Unicode support.
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*
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* This file is part of libostd. See COPYING.md for futher information.
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*/
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#include <cstdint>
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#include <cstdlib>
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#include "ostd/string.hh"
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namespace ostd {
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namespace utf {
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constexpr std::uint32_t MaxCodepoint = 0x10FFFF;
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namespace detail {
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static inline bool u8_decode(string_range &r, char32_t &cret) noexcept {
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static std::uint32_t const ulim[] = { 0xFF, 0x7F, 0x7FF, 0xFFFF };
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if (r.empty()) {
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return false;
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}
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std::uint32_t ch = static_cast<unsigned char const>(r.front());
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if (ch <= 0x7F) {
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/* ASCII */
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cret = ch;
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r.pop_front();
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return true;
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}
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std::uint32_t ret = 0;
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string_range sr = r;
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sr.pop_front();
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/* continuation bytes */
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for (; ch & 0x40; ch <<= 1) {
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/* need a continuation byte but nothing left in the string */
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if (sr.empty()) {
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return false;
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}
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/* the continuation byte */
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std::uint32_t nch = static_cast<unsigned char const>(sr.front());
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sr.pop_front();
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/* lower 6 bits */
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std::uint32_t bch = nch & 0x3F;
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/* not a continuation byte */
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if ((nch ^ bch) != 0x80) {
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return false;
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}
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/* the 6 bits go in the result */
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ret = (ret << 6) | bch;
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}
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/* number of continuation bytes */
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auto n = sr.data() - r.data() - 1;
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/* invalid sequence - too many continuation bits */
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if (n > 3) {
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return false;
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}
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/* add the up to 7 bits from the first byte, already shifted left by n */
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ret |= (ch & 0x7F) << (n * 5);
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/* invalid sequence - out of bounds */
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if ((ret > MaxCodepoint) || (ret <= ulim[n])) {
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return false;
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}
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/* invalid sequence - surrogate code point */
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if ((ret >= 0xD800) && (ret <= 0xDFFF)) {
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return false;
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}
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cret = ret;
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r = sr;
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return true;
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}
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std::uint8_t u8_encode(
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std::uint8_t (&ret)[4], std::uint32_t ch
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) noexcept {
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if (ch <= 0x7F) {
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ret[0] = std::uint8_t(ch);
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return 1;
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}
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if (ch <= 0x7FF) {
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ret[0] = std::uint8_t(0xC0 | (ch >> 6));
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ret[1] = std::uint8_t(0x80 | (ch & 0x3F));
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return 2;
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}
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if (ch <= 0xFFFF) {
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/* TODO: optional WTF-8 semantics
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* for now simply reject surrogate code points
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*/
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if ((ch >= 0xD800) && (ch <= 0xDFFF)) {
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return 0;
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}
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ret[0] = std::uint8_t(0xE0 | (ch >> 12));
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ret[1] = std::uint8_t(0x80 | ((ch >> 6) & 0x3F));
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ret[2] = std::uint8_t(0x80 | (ch & 0x3F));
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return 3;
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}
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if (ch <= MaxCodepoint) {
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ret[0] = std::uint8_t(0xF0 | (ch >> 18));
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ret[1] = std::uint8_t(0x80 | ((ch >> 12) | 0x3F));
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ret[2] = std::uint8_t(0x80 | ((ch >> 6) | 0x3F));
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ret[3] = std::uint8_t(0x80 | (ch | 0x3F));
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return 4;
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}
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return 0;
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}
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} /* namespace detail */
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bool decode(string_range &r, char32_t &ret) noexcept {
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return detail::u8_decode(r, ret);
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}
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std::size_t length(string_range r, string_range &cont) noexcept {
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std::size_t ret = 0;
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for (char32_t ch = U'\0'; detail::u8_decode(r, ch); ++ret) {
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continue;
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}
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cont = r;
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return ret;
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}
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/* unicode-aware ctype
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* the other ones use custom tables for lookups
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*/
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bool isalnum(char32_t c) noexcept {
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return (utf::isalpha(c) || utf::isdigit(c));
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}
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bool isblank(char32_t c) noexcept {
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return ((c == ' ') || (c == '\t'));
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}
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bool isgraph(char32_t c) noexcept {
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return (!utf::isspace(c) && utf::isprint(c));
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}
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bool isprint(char32_t c) noexcept {
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switch (std::uint32_t(c)) {
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case 0x2028:
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case 0x2029:
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case 0xFFF9:
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case 0xFFFA:
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case 0xFFFB:
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return false;
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default:
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return !utf::iscntrl(c);
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}
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}
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bool ispunct(char32_t c) noexcept {
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return (utf::isgraph(c) && !utf::isalnum(c));
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}
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bool isvalid(char32_t c) noexcept {
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/* surrogate code points */
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if ((c >= 0xD800) && (c <= 0xDFFF)) {
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return false;
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}
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/* non-characters */
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if ((c >= 0xFDD0) && (c <= 0xFDEF)) {
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return false;
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}
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/* end of plane */
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if ((c & 0xFFFE) == 0xFFFE) {
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return false;
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}
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/* must be within range */
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return (c <= MaxCodepoint);
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}
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bool isxdigit(char32_t c) noexcept {
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if ((c >= '0') && (c <= '9')) {
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return true;
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}
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auto uc = std::uint32_t(c) | 32;
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return ((uc >= 'a') && (uc <= 'f'));
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}
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inline int codepoint_cmp1(void const *a, void const *b) noexcept {
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char32_t c1 = *static_cast<char32_t const *>(a);
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char32_t c2 = *static_cast<char32_t const *>(b);
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return (int(c1) - int(c2));
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}
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inline int codepoint_cmp2(void const *a, void const *b) noexcept {
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char32_t c = *static_cast<char32_t const *>(a);
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char32_t const *p = static_cast<char32_t const *>(b);
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if ((c >= p[0]) && (c <= p[1])) {
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return 0;
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}
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return (int(c) - int(p[0]));
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}
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template<
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std::size_t RN, std::size_t RS,
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std::size_t L1N, std::size_t L1S,
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std::size_t L2N, std::size_t L2S,
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std::size_t SN, std::size_t SS
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>
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struct uctype_func {
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template<std::size_t N, std::size_t S>
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static char32_t *search(
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char32_t c, void const *arr, int (*cmp)(void const *, void const *)
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) noexcept {
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return static_cast<char32_t *>(std::bsearch(&c, arr, N / S, S, cmp));
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}
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static bool do_is(
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char32_t c,
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void const *ranges [[maybe_unused]],
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void const *laces1 [[maybe_unused]],
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void const *laces2 [[maybe_unused]],
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void const *singles [[maybe_unused]]
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) noexcept {
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if constexpr(RN != 0) {
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char32_t *found = search<RN, RS>(c, ranges, codepoint_cmp2);
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if (found) {
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return true;
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}
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}
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if constexpr(L1N != 0) {
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char32_t *found = search<L1N, L1S>(c, laces1, codepoint_cmp2);
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if (found) {
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return !((c - found[0]) % 2);
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}
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}
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if constexpr(L2N != 0) {
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char32_t *found = search<L2N, L2S>(c, laces2, codepoint_cmp2);
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if (found) {
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return !((c - found[0]) % 2);
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}
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}
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if constexpr(SN != 0) {
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char32_t *found = search<SN, SS>(c, singles, codepoint_cmp1);
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if (found) {
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return true;
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}
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}
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return false;
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}
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static char32_t do_to(
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char32_t c,
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void const *ranges [[maybe_unused]],
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void const *laces1 [[maybe_unused]],
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void const *laces2 [[maybe_unused]],
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void const *singles [[maybe_unused]]
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) noexcept {
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if constexpr(RN != 0) {
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char32_t *found = search<RN, RS>(c, ranges, codepoint_cmp2);
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if (found) {
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return (found[2] + (c - found[0]));
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}
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}
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if constexpr(L1N != 0) {
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char32_t *found = search<L1N, L1S>(c, laces1, codepoint_cmp2);
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if (found) {
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if ((c - found[0]) % 2) {
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return c;
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}
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return c + 1;
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}
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}
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if constexpr(L2N != 0) {
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char32_t *found = search<L2N, L2S>(c, laces2, codepoint_cmp2);
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if (found) {
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if ((c - found[0]) % 2) {
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return c;
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}
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return c - 1;
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}
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}
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if constexpr(SN != 0) {
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char32_t *found = search<SN, SS>(c, singles, codepoint_cmp1);
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if (found) {
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return found[1];
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}
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}
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return c;
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}
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};
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/* these are geneated */
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bool isalpha(char32_t c) noexcept;
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bool iscntrl(char32_t c) noexcept;
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bool isdigit(char32_t c) noexcept;
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bool islower(char32_t c) noexcept;
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bool isspace(char32_t c) noexcept;
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bool istitle(char32_t c) noexcept;
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bool isupper(char32_t c) noexcept;
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char32_t tolower(char32_t c) noexcept;
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char32_t toupper(char32_t c) noexcept;
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#if __has_include("string_utf.hh")
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#include "string_utf.hh"
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#else
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/* break the cycle (build system and generator use libostd, but string_utf.hh
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* is generated during build) by providing a bunch of ASCII only fallbacks
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*/
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bool isalpha(char32_t c) noexcept {
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return (utf::isupper(c) || utf::islower(c));
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}
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bool iscntrl(char32_t c) noexcept {
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return ((c <= 0x1F) || (c == 0x7F));
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}
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bool isdigit(char32_t c) noexcept {
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return ((c >= '0') && (c <= '9'));
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}
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bool islower(char32_t c) noexcept {
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return ((c >= 'a') && (c <= 'z'));
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}
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bool isspace(char32_t c) noexcept {
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return ((c == ' ') || ((c >= 0x09) && (c <= 0x0D)));
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}
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bool istitle(char32_t) noexcept {
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return false;
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}
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bool isupper(char32_t c) noexcept {
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return ((c >= 'A') && (c <= 'Z'));
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}
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char32_t tolower(char32_t c) noexcept {
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if (utf::isupper(c)) {
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return c | 32;
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}
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return c;
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}
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char32_t toupper(char32_t c) noexcept {
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if (utf::islower(c)) {
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return c ^ 32;
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}
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return c;
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}
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#endif /* __has_include("string_utf.hh") */
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int case_compare(string_range s1, string_range s2) noexcept {
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std::size_t s1l = s1.size(), s2l = s2.size(), ms = std::min(s1l, s2l);
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s1 = s1.slice(0, ms);
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s2 = s2.slice(0, ms);
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for (;;) {
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/* enforce correct semantics with signed chars; first convert to
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* 8-bit unsigned and then to char32_t (which is always unsigned)
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* in order to not get large values from 32-bit unsigned underflow
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*/
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auto ldec = char32_t(std::uint8_t(s1.front()));
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auto rdec = char32_t(std::uint8_t(s2.front()));
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if ((ldec <= 0x7F) || !utf::decode(s1, ldec)) {
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s1.pop_front();
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}
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if ((rdec <= 0x7F) || !utf::decode(s2, rdec)) {
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s2.pop_front();
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}
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int d = int(utf::tolower(ldec)) - int(utf::tolower(rdec));
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if (d) {
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return d;
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}
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if (s1.empty() || s2.empty()) {
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s1l = s1.size();
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s2l = s2.size();
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break;
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}
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}
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return (s1l < s2l) ? -1 : ((s1l > s2l) ? 1 : 0);
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}
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int case_compare(u32string_range s1, u32string_range s2) noexcept {
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std::size_t s1l = s1.size(), s2l = s2.size();
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for (std::size_t i = 0, ms = std::min(s1l, s2l); i < ms; ++i) {
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int d = int(utf::tolower(s1[i])) - int(utf::tolower(s2[i]));
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if (d) {
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return d;
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}
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}
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return (s1l < s2l) ? -1 : ((s1l > s2l) ? 1 : 0);
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}
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} /* namespace utf */
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} /* namespace ostd */
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