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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2023
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/utils/utf8.h"
#include "td/utils/misc.h"
#include "td/utils/SliceBuilder.h"
#include "td/utils/unicode.h"
namespace td {
bool check_utf8(CSlice str) {
const char *data = str.data();
const char *data_end = data + str.size();
do {
uint32 a = static_cast<unsigned char>(*data++);
if ((a & 0x80) == 0) {
if (data == data_end + 1) {
return true;
}
continue;
}
#define ENSURE(condition) \
if (!(condition)) { \
return false; \
}
ENSURE((a & 0x40) != 0);
uint32 b = static_cast<unsigned char>(*data++);
ENSURE((b & 0xc0) == 0x80);
if ((a & 0x20) == 0) {
ENSURE((a & 0x1e) > 0);
continue;
}
uint32 c = static_cast<unsigned char>(*data++);
ENSURE((c & 0xc0) == 0x80);
if ((a & 0x10) == 0) {
uint32 x = (((a & 0x0f) << 6) | (b & 0x20));
ENSURE(x != 0 && x != 0x360); // surrogates
continue;
}
uint32 d = static_cast<unsigned char>(*data++);
ENSURE((d & 0xc0) == 0x80);
if ((a & 0x08) == 0) {
uint32 t = (((a & 0x07) << 6) | (b & 0x30));
ENSURE(0 < t && t < 0x110); // end of unicode
continue;
}
return false;
#undef ENSURE
} while (true);
UNREACHABLE();
return false;
}
const unsigned char *next_utf8_unsafe(const unsigned char *ptr, uint32 *code) {
uint32 a = ptr[0];
if ((a & 0x80) == 0) {
*code = a;
return ptr + 1;
} else if ((a & 0x20) == 0) {
*code = ((a & 0x1f) << 6) | (ptr[1] & 0x3f);
return ptr + 2;
} else if ((a & 0x10) == 0) {
*code = ((a & 0x0f) << 12) | ((ptr[1] & 0x3f) << 6) | (ptr[2] & 0x3f);
return ptr + 3;
} else if ((a & 0x08) == 0) {
*code = ((a & 0x07) << 18) | ((ptr[1] & 0x3f) << 12) | ((ptr[2] & 0x3f) << 6) | (ptr[3] & 0x3f);
return ptr + 4;
}
UNREACHABLE();
*code = 0;
return ptr;
}
unsigned char *append_utf8_character_unsafe(unsigned char *ptr, uint32 code) {
if (code <= 0x7f) {
*ptr++ = static_cast<unsigned char>(code);
} else if (code <= 0x7ff) {
*ptr++ = static_cast<unsigned char>(0xc0 | (code >> 6));
*ptr++ = static_cast<unsigned char>(0x80 | (code & 0x3f));
} else if (code <= 0xffff) {
*ptr++ = static_cast<unsigned char>(0xe0 | (code >> 12));
*ptr++ = static_cast<unsigned char>(0x80 | ((code >> 6) & 0x3f));
*ptr++ = static_cast<unsigned char>(0x80 | (code & 0x3f));
} else {
*ptr++ = static_cast<unsigned char>(0xf0 | (code >> 18));
*ptr++ = static_cast<unsigned char>(0x80 | ((code >> 12) & 0x3f));
*ptr++ = static_cast<unsigned char>(0x80 | ((code >> 6) & 0x3f));
*ptr++ = static_cast<unsigned char>(0x80 | (code & 0x3f));
}
return ptr;
}
string utf8_to_lower(Slice str) {
string result;
auto pos = str.ubegin();
auto end = str.uend();
while (pos != end) {
uint32 code;
pos = next_utf8_unsafe(pos, &code);
append_utf8_character(result, unicode_to_lower(code));
}
return result;
}
vector<string> utf8_get_search_words(Slice str) {
bool in_word = false;
string word;
vector<string> words;
auto pos = str.ubegin();
auto end = str.uend();
while (pos != end) {
uint32 code;
pos = next_utf8_unsafe(pos, &code);
code = prepare_search_character(code);
if (code == 0) {
continue;
}
if (code == ' ') {
if (in_word) {
words.push_back(std::move(word));
word.clear();
in_word = false;
}
} else {
in_word = true;
code = remove_diacritics(code);
append_utf8_character(word, code);
}
}
if (in_word) {
words.push_back(std::move(word));
}
return words;
}
string utf8_prepare_search_string(Slice str) {
return implode(utf8_get_search_words(str));
}
string utf8_encode(CSlice data) {
if (check_utf8(data)) {
return data.str();
}
return PSTRING() << "url_decode(" << url_encode(data) << ')';
}
size_t utf8_utf16_length(Slice str) {
size_t result = 0;
for (auto c : str) {
result += is_utf8_character_first_code_unit(c) + ((c & 0xf8) == 0xf0);
}
return result;
}
Slice utf8_utf16_truncate(Slice str, size_t length) {
for (size_t i = 0; i < str.size(); i++) {
auto c = static_cast<unsigned char>(str[i]);
if (is_utf8_character_first_code_unit(c)) {
if (length <= 0) {
return str.substr(0, i);
} else {
length--;
if (c >= 0xf0) { // >= 4 bytes in symbol => surrogate pair
length--;
}
}
}
}
return str;
}
Slice utf8_utf16_substr(Slice str, size_t offset) {
if (offset == 0) {
return str;
}
auto offset_pos = utf8_utf16_truncate(str, offset).size();
return str.substr(offset_pos);
}
Slice utf8_utf16_substr(Slice str, size_t offset, size_t length) {
return utf8_utf16_truncate(utf8_utf16_substr(str, offset), length);
}
} // namespace td
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