mirror of
https://github.com/ton-blockchain/ton
synced 2025-03-09 15:40:10 +00:00
118 lines
3.4 KiB
C++
118 lines
3.4 KiB
C++
/*
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This file is part of TON Blockchain Library.
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TON Blockchain Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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TON Blockchain Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
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Copyright 2017-2019 Telegram Systems LLP
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*/
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#pragma once
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#include "td/utils/common.h"
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#include "td/utils/Slice.h"
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namespace td {
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/// checks UTF-8 string for correctness
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bool check_utf8(CSlice str);
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/// checks if a code unit is a first code unit of a UTF-8 character
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inline bool is_utf8_character_first_code_unit(unsigned char c) {
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return (c & 0xC0) != 0x80;
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}
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/// returns length of UTF-8 string in characters
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inline size_t utf8_length(Slice str) {
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size_t result = 0;
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for (auto c : str) {
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result += is_utf8_character_first_code_unit(c);
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}
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return result;
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}
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/// appends a Unicode character using UTF-8 encoding
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void append_utf8_character(string &str, uint32 ch);
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/// moves pointer one UTF-8 character back
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inline const unsigned char *prev_utf8_unsafe(const unsigned char *ptr) {
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while (!is_utf8_character_first_code_unit(*--ptr)) {
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// pass
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}
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return ptr;
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}
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/// moves pointer one UTF-8 character forward and saves code of the skipped character in *code
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const unsigned char *next_utf8_unsafe(const unsigned char *ptr, uint32 *code, const char *source);
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/// truncates UTF-8 string to the given length in Unicode characters
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template <class T>
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T utf8_truncate(T str, size_t length) {
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if (str.size() > length) {
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for (size_t i = 0; i < str.size(); i++) {
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if (is_utf8_character_first_code_unit(static_cast<unsigned char>(str[i]))) {
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if (length == 0) {
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return str.substr(0, i);
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} else {
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length--;
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}
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}
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}
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}
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return str;
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}
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/// truncates UTF-8 string to the given length given in UTF-16 code units
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template <class T>
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T utf8_utf16_truncate(T str, size_t length) {
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for (size_t i = 0; i < str.size(); i++) {
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auto c = static_cast<unsigned char>(str[i]);
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if (is_utf8_character_first_code_unit(c)) {
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if (length <= 0) {
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return str.substr(0, i);
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} else {
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length--;
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if (c >= 0xf0) { // >= 4 bytes in symbol => surrogaite pair
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length--;
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}
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}
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}
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}
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return str;
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}
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template <class T>
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T utf8_substr(T str, size_t offset) {
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auto offset_pos = utf8_truncate(str, offset).size();
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return str.substr(offset_pos);
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}
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template <class T>
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T utf8_substr(T str, size_t offset, size_t length) {
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return utf8_truncate(utf8_substr(str, offset), length);
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}
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template <class T>
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T utf8_utf16_substr(T str, size_t offset) {
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auto offset_pos = utf8_utf16_truncate(str, offset).size();
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return str.substr(offset_pos);
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}
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template <class T>
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T utf8_utf16_substr(T str, size_t offset, size_t length) {
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return utf8_utf16_truncate(utf8_utf16_substr(str, offset), length);
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}
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/// Returns UTF-8 string converted to lower case.
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string utf8_to_lower(Slice str);
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} // namespace td
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