#include "unicode.h"
#include <algorithm>
#include <cassert>
#include <stdexcept>
#include <string>
#include <vector>
// implementation adopted from src/unicode.cpp
size_t common_utf8_sequence_length(unsigned char first_byte) {
const size_t lookup[] = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 4 };
uint8_t highbits = static_cast<uint8_t>(first_byte) >> 4;
return lookup[highbits];
}
utf8_parse_result common_parse_utf8_codepoint(std::string_view input, size_t offset) {
if (offset >= input.size()) {
return utf8_parse_result(utf8_parse_result::INCOMPLETE);
}
// ASCII fast path
if (!(input[offset] & 0x80)) {
return utf8_parse_result(utf8_parse_result::SUCCESS, input[offset], 1);
}
// Invalid: continuation byte as first byte
if (!(input[offset] & 0x40)) {
return utf8_parse_result(utf8_parse_result::INVALID);
}
// 2-byte sequence
if (!(input[offset] & 0x20)) {
if (offset + 1 >= input.size()) {
return utf8_parse_result(utf8_parse_result::INCOMPLETE);
}
if ((input[offset + 1] & 0xc0) != 0x80) {
return utf8_parse_result(utf8_parse_result::INVALID);
}
auto result = ((input[offset] & 0x1f) << 6) | (input[offset + 1] & 0x3f);
return utf8_parse_result(utf8_parse_result::SUCCESS, result, 2);
}
// 3-byte sequence
if (!(input[offset] & 0x10)) {
if (offset + 2 >= input.size()) {
return utf8_parse_result(utf8_parse_result::INCOMPLETE);
}
if ((input[offset + 1] & 0xc0) != 0x80 || (input[offset + 2] & 0xc0) != 0x80) {
return utf8_parse_result(utf8_parse_result::INVALID);
}
auto result = ((input[offset] & 0x0f) << 12) | ((input[offset + 1] & 0x3f) << 6) | (input[offset + 2] & 0x3f);
return utf8_parse_result(utf8_parse_result::SUCCESS, result, 3);
}
// 4-byte sequence
if (!(input[offset] & 0x08)) {
if (offset + 3 >= input.size()) {
return utf8_parse_result(utf8_parse_result::INCOMPLETE);
}
if ((input[offset + 1] & 0xc0) != 0x80 || (input[offset + 2] & 0xc0) != 0x80 || (input[offset + 3] & 0xc0) != 0x80) {
return utf8_parse_result(utf8_parse_result::INVALID);
}
auto result = ((input[offset] & 0x07) << 18) | ((input[offset + 1] & 0x3f) << 12) | ((input[offset + 2] & 0x3f) << 6) | (input[offset + 3] & 0x3f);
return utf8_parse_result(utf8_parse_result::SUCCESS, result, 4);
}
// Invalid first byte
return utf8_parse_result(utf8_parse_result::INVALID);
}
bool common_utf8_is_complete(const std::string & s) {
if (s.empty()) {
return true;
}
for (int i = 1; i <= std::min(4, (int)s.size()); i++) {
unsigned char c = s[s.size() - i];
if ((c & 0xC0) != 0x80) {
int expected = (c >= 0xF0) ? 4 : (c >= 0xE0) ? 3 : (c >= 0xC0) ? 2 : 1;
return i >= expected;
}
}
return false;
}
std::string common_unicode_cpts_to_utf8(const std::vector<uint32_t> & cps) {
std::string result;
for (size_t i = 0; i < cps.size(); ++i) {
result.append(common_unicode_cpt_to_utf8(cps[i]));
}
return result;
}
std::string common_unicode_cpt_to_utf8(uint32_t cpt) {
std::string result;
if (/* 0x00 <= cpt && */ cpt <= 0x7f) {
result.push_back(cpt);
return result;
}
if (0x80 <= cpt && cpt <= 0x7ff) {
result.push_back(0xc0 | ((cpt >> 6) & 0x1f));
result.push_back(0x80 | (cpt & 0x3f));
return result;
}
if (0x800 <= cpt && cpt <= 0xffff) {
result.push_back(0xe0 | ((cpt >> 12) & 0x0f));
result.push_back(0x80 | ((cpt >> 6) & 0x3f));
result.push_back(0x80 | (cpt & 0x3f));
return result;
}
if (0x10000 <= cpt && cpt <= 0x10ffff) {
result.push_back(0xf0 | ((cpt >> 18) & 0x07));
result.push_back(0x80 | ((cpt >> 12) & 0x3f));
result.push_back(0x80 | ((cpt >> 6) & 0x3f));
result.push_back(0x80 | (cpt & 0x3f));
return result;
}
throw std::invalid_argument("invalid codepoint");
}