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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/fts/fts_unicode_tokenizer.h"
#include <memory>
#include "mongo/db/fts/fts_query_impl.h"
#include "mongo/db/fts/fts_spec.h"
#include "mongo/db/fts/stemmer.h"
#include "mongo/db/fts/stop_words.h"
#include "mongo/db/fts/tokenizer.h"
#include "mongo/util/str.h"
namespace mongo {
namespace fts {
using std::string;
UnicodeFTSTokenizer::UnicodeFTSTokenizer(const FTSLanguage* language)
: _language(language),
_stemmer(language),
_stopWords(StopWords::getStopWords(language)),
_delimListLanguage(_language->str() == "english"
? unicode::DelimiterListLanguage::kEnglish
: unicode::DelimiterListLanguage::kNotEnglish),
_caseFoldMode(_language->str() == "turkish" ? unicode::CaseFoldMode::kTurkish
: unicode::CaseFoldMode::kNormal) {}
void UnicodeFTSTokenizer::reset(StringData document, Options options) {
_options = options;
_pos = 0;
_document.resetData(document); // Validates that document is valid UTF8.
// Skip any leading delimiters (and handle the case where the document is entirely delimiters).
_skipDelimiters();
}
bool UnicodeFTSTokenizer::moveNext() {
while (true) {
if (_pos >= _document.size()) {
_word = "";
return false;
}
// Traverse through non-delimiters and build the next token.
size_t start = _pos++;
while (_pos < _document.size() &&
(!unicode::codepointIsDelimiter(_document[_pos], _delimListLanguage))) {
++_pos;
}
const size_t len = _pos - start;
// Skip the delimiters before the next token.
_skipDelimiters();
// Stop words are case-sensitive and diacritic sensitive, so we need them to be lower cased
// but with diacritics not removed to check against the stop word list.
_word = _document.toLowerToBuf(&_wordBuf, _caseFoldMode, start, len);
if ((_options & kFilterStopWords) && _stopWords->isStopWord(_word)) {
continue;
}
if (_options & kGenerateCaseSensitiveTokens) {
_word = _document.substrToBuf(&_wordBuf, start, len);
}
// The stemmer is diacritic sensitive, so stem the word before removing diacritics.
_word = _stemmer.stem(_word);
if (!(_options & kGenerateDiacriticSensitiveTokens)) {
// Can't use _wordbuf for output here because our input _word may point into it.
_word = unicode::String::caseFoldAndStripDiacritics(
&_finalBuf, _word, unicode::String::kCaseSensitive, _caseFoldMode);
}
return true;
}
}
StringData UnicodeFTSTokenizer::get() const {
return _word;
}
void UnicodeFTSTokenizer::_skipDelimiters() {
while (_pos < _document.size() &&
unicode::codepointIsDelimiter(_document[_pos], _delimListLanguage)) {
++_pos;
}
}
} // namespace fts
} // namespace mongo
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