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Improve encoding detection by making the string larger #488

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merged 1 commit into from
Dec 27, 2024
Merged

Improve encoding detection by making the string larger #488

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25 changes: 23 additions & 2 deletions src/reader_util.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -142,13 +142,32 @@ std::vector<std::string> ReaderUtil::DetectEncodings(StringView string) {
UCharsetDetector* detector = ucsdet_open(&status);

auto s = std::string(string);
ucsdet_setText(detector, s.c_str(), s.length(), &status);

int confidence = 0;
int32_t matches_count;
const UCharsetMatch** matches = ucsdet_detectAll(detector, &matches_count, &status);
const UCharsetMatch** matches = nullptr;

while (true) {
ucsdet_setText(detector, s.c_str(), s.length(), &status);
matches = ucsdet_detectAll(detector, &matches_count, &status);

if (!matches || matches_count < 1) {
break;
}

confidence = ucsdet_getConfidence(matches[0], &status);

if (confidence > 70 || s.length() > 100) {
break;
}

// Concatenating the string to itself increases the confidence (for short strings)
s += s;
}

if (matches != nullptr) {
// Collect all candidates, most confident comes first

for (int i = 0; i < matches_count; ++i) {
std::string encoding = ucsdet_getName(matches[i], &status);

Expand All @@ -171,6 +190,8 @@ std::vector<std::string> ReaderUtil::DetectEncodings(StringView string) {
encodings.emplace_back("ibm-5349_P100-1998"); // Greek with Euro
} else if (encoding == "ISO-8859-8" || encoding == "windows-1255") {
encodings.emplace_back("ibm-9447_P100-2002"); // Hebrew with Euro
} else if (encoding == "UTF-16BE" || encoding == "UTF-16LE") {
// ignore encodings that are obviously wrong
} else {
encodings.push_back(encoding);
}
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