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[utf8_decoder] Better code for CharSizeOfCodePoint

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This commit is contained in:
Léa Saviot
2019-01-23 16:26:14 +01:00
committed by Émilie Feral
parent 7020ecef57
commit 1048478cd2
1 changed files with 17 additions and 7 deletions
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24
ion/src/shared/unicode/utf8_decoder.cpp
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@@ -56,9 +56,16 @@ CodePoint UTF8Decoder::previousCodePoint() {
}
size_t UTF8Decoder::CharSizeOfCodePoint(CodePoint c) {
constexpr int bufferSize = CodePoint::MaxCodePointCharLength;
char buffer[bufferSize];
return CodePointToChars(c, buffer, bufferSize);
if (c <= 0x7F) {
return 1;
}
if (c <= 0x7FF) {
return 2;
}
if (c <= 0xFFFF) {
return 3;
}
return 4;
}
size_t UTF8Decoder::CodePointToChars(CodePoint c, char * buffer, int bufferSize) {
@@ -66,19 +73,21 @@ size_t UTF8Decoder::CodePointToChars(CodePoint c, char * buffer, int bufferSize)
return 0;
}
size_t i = 0;
if (c <= 0x7F) {
int charCount = CharSizeOfCodePoint(c);
if (charCount == 1) {
buffer[i++] = c;
} else if (c <= 0x7FF) {
} else if (charCount == 2) {
buffer[i++] = 0b11000000 | (c >> 6);
if (bufferSize <= i) { return i; }
buffer[i++] = 0b10000000 | (c & 0b111111);
} else if (c <= 0xFFFF) {
} else if (charCount == 3) {
buffer[i++] = 0b11100000 | (c >> 12);
if (bufferSize <= i) { return i; }
buffer[i++] = 0b10000000 | ((c >> 6) & 0b111111);
if (bufferSize <= i) { return i; }
buffer[i++] = 0b10000000 | (c & 0b111111);
} else {
assert(charCount == 4);
buffer[i++] = 0b11110000 | (c >> 18);
if (bufferSize <= i) { return i; }
buffer[i++] = 0b10000000 | ((c >> 12) & 0b111111);
@@ -87,5 +96,6 @@ size_t UTF8Decoder::CodePointToChars(CodePoint c, char * buffer, int bufferSize)
if (bufferSize <= i) { return i; }
buffer[i++] = 0b10000000 | (c & 0b111111);
}
return i;
assert(i == charCount);
return charCount;
}