89 lines
2.7 KiB
C++
89 lines
2.7 KiB
C++
|
// Copyright 2004-present Facebook. All Rights Reserved.
|
||
|
|
|
||
|
|
#include "Unicode.h"
|
||
|
|
|
||
|
|
namespace facebook {
|
||
|
|
namespace react {
|
||
|
|
namespace unicode {
|
||
|
|
namespace {
|
||
|
|
|
||
|
|
// TODO(12827176): Don't duplicate this code here and fbjni.
|
||
|
|
|
||
|
|
const uint16_t kUtf8OneByteBoundary = 0x80;
|
||
|
|
const uint16_t kUtf8TwoBytesBoundary = 0x800;
|
||
|
|
const uint16_t kUtf16HighSubLowBoundary = 0xD800;
|
||
|
|
const uint16_t kUtf16HighSubHighBoundary = 0xDC00;
|
||
|
|
const uint16_t kUtf16LowSubHighBoundary = 0xE000;
|
||
|
|
|
||
|
|
// Calculate how many bytes are needed to convert an UTF16 string into UTF8
|
||
|
|
// UTF16 string
|
||
|
|
size_t utf16toUTF8Length(const uint16_t* utf16String, size_t utf16StringLen) {
|
||
|
|
if (!utf16String || utf16StringLen == 0) {
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
uint32_t utf8StringLen = 0;
|
||
|
|
auto utf16StringEnd = utf16String + utf16StringLen;
|
||
|
|
auto idx16 = utf16String;
|
||
|
|
while (idx16 < utf16StringEnd) {
|
||
|
|
auto ch = *idx16++;
|
||
|
|
if (ch < kUtf8OneByteBoundary) {
|
||
|
|
utf8StringLen++;
|
||
|
|
} else if (ch < kUtf8TwoBytesBoundary) {
|
||
|
|
utf8StringLen += 2;
|
||
|
|
} else if (
|
||
|
|
(ch >= kUtf16HighSubLowBoundary) && (ch < kUtf16HighSubHighBoundary) &&
|
||
|
|
(idx16 < utf16StringEnd) &&
|
||
|
|
(*idx16 >= kUtf16HighSubHighBoundary) && (*idx16 < kUtf16LowSubHighBoundary)) {
|
||
|
|
utf8StringLen += 4;
|
||
|
|
idx16++;
|
||
|
|
} else {
|
||
|
|
utf8StringLen += 3;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return utf8StringLen;
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace
|
||
|
|
|
||
|
|
std::string utf16toUTF8(const uint16_t* utf16String, size_t utf16StringLen) noexcept {
|
||
|
|
if (!utf16String || utf16StringLen <= 0) {
|
||
|
|
return "";
|
||
|
|
}
|
||
|
|
|
||
|
|
std::string utf8String(utf16toUTF8Length(utf16String, utf16StringLen), '\0');
|
||
|
|
auto idx8 = utf8String.begin();
|
||
|
|
auto idx16 = utf16String;
|
||
|
|
auto utf16StringEnd = utf16String + utf16StringLen;
|
||
|
|
while (idx16 < utf16StringEnd) {
|
||
|
|
auto ch = *idx16++;
|
||
|
|
if (ch < kUtf8OneByteBoundary) {
|
||
|
|
*idx8++ = (ch & 0x7F);
|
||
|
|
} else if (ch < kUtf8TwoBytesBoundary) {
|
||
|
|
*idx8++ = 0b11000000 | (ch >> 6);
|
||
|
|
*idx8++ = 0b10000000 | (ch & 0x3F);
|
||
|
|
} else if (
|
||
|
|
(ch >= kUtf16HighSubLowBoundary) && (ch < kUtf16HighSubHighBoundary) &&
|
||
|
|
(idx16 < utf16StringEnd) &&
|
||
|
|
(*idx16 >= kUtf16HighSubHighBoundary) && (*idx16 < kUtf16LowSubHighBoundary)) {
|
||
|
|
auto ch2 = *idx16++;
|
||
|
|
uint8_t trunc_byte = (((ch >> 6) & 0x0F) + 1);
|
||
|
|
*idx8++ = 0b11110000 | (trunc_byte >> 2);
|
||
|
|
*idx8++ = 0b10000000 | ((trunc_byte & 0x03) << 4) | ((ch >> 2) & 0x0F);
|
||
|
|
*idx8++ = 0b10000000 | ((ch & 0x03) << 4) | ((ch2 >> 6) & 0x0F);
|
||
|
|
*idx8++ = 0b10000000 | (ch2 & 0x3F);
|
||
|
|
} else {
|
||
|
|
*idx8++ = 0b11100000 | (ch >> 12);
|
||
|
|
*idx8++ = 0b10000000 | ((ch >> 6) & 0x3F);
|
||
|
|
*idx8++ = 0b10000000 | (ch & 0x3F);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return utf8String;
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace unicode
|
||
|
|
} // namespace react
|
||
|
|
} // namespace facebook
|