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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.
*/
#pragma once
#include <map>
#include <string>
#include <vector>
#include "mongo/base/status_with.h"
#include "mongo/db/fts/fts_language.h"
#include "mongo/db/fts/fts_util.h"
#include "mongo/db/fts/stemmer.h"
#include "mongo/db/fts/stop_words.h"
#include "mongo/db/fts/tokenizer.h"
#include "mongo/stdx/unordered_map.h"
#include "mongo/util/string_map.h"
namespace mongo {
namespace fts {
extern const double MAX_WEIGHT;
extern const double MAX_WORD_WEIGHT;
extern const double DEFAULT_WEIGHT;
typedef std::map<std::string, double> Weights; // TODO cool map
typedef stdx::unordered_map<std::string, double> TermFrequencyMap;
struct ScoreHelperStruct {
ScoreHelperStruct() : freq(0), count(0), exp(0) {}
double freq;
double count;
double exp;
};
typedef StringMap<ScoreHelperStruct> ScoreHelperMap;
class FTSSpec {
struct Tools {
Tools(const FTSLanguage& _language, const Stemmer* _stemmer, const StopWords* _stopwords)
: language(_language), stemmer(_stemmer), stopwords(_stopwords) {}
const FTSLanguage& language;
const Stemmer* stemmer;
const StopWords* stopwords;
};
public:
FTSSpec(const BSONObj& indexInfo);
bool wildcard() const {
return _wildcard;
}
const FTSLanguage& defaultLanguage() const {
return *_defaultLanguage;
}
const std::string& languageOverrideField() const {
return _languageOverrideField;
}
size_t numExtraBefore() const {
return _extraBefore.size();
}
const std::string& extraBefore(unsigned i) const {
return _extraBefore[i];
}
size_t numExtraAfter() const {
return _extraAfter.size();
}
const std::string& extraAfter(unsigned i) const {
return _extraAfter[i];
}
/**
* Calculates term/score pairs for a BSONObj as applied to this spec.
* @arg obj document to traverse; can be a subdocument or array
* @arg term_freqs output parameter to store (term,score) results
*/
void scoreDocument(const BSONObj& obj, TermFrequencyMap* term_freqs) const;
/**
* given a query, pulls out the pieces (in order) that go in the index first
*/
Status getIndexPrefix(const BSONObj& filter, BSONObj* out) const;
const Weights& weights() const {
return _weights;
}
static StatusWith<BSONObj> fixSpec(const BSONObj& spec);
/**
* Returns text index version.
*/
TextIndexVersion getTextIndexVersion() const {
return _textIndexVersion;
}
private:
//
// Helper methods. Invoked for TEXT_INDEX_VERSION_2 spec objects only.
//
/**
* Calculate the term scores for 'raw' and update 'term_freqs' with the result. Parses
* 'raw' using 'tools', and weights term scores based on 'weight'.
*/
void _scoreStringV2(FTSTokenizer* tokenizer,
StringData raw,
TermFrequencyMap* term_freqs,
double weight) const;
public:
/**
* Get the language override for the given BSON doc. If no language override is
* specified, returns currentLanguage.
*/
const FTSLanguage* _getLanguageToUseV2(const BSONObj& userDoc,
const FTSLanguage* currentLanguage) const;
private:
//
// Deprecated helper methods. Invoked for TEXT_INDEX_VERSION_1 spec objects only.
//
void _scoreStringV1(const Tools& tools,
StringData raw,
TermFrequencyMap* docScores,
double weight) const;
bool _weightV1(StringData field, double* out) const;
void _scoreRecurseV1(const Tools& tools,
const BSONObj& obj,
TermFrequencyMap* term_freqs) const;
void _scoreDocumentV1(const BSONObj& obj, TermFrequencyMap* term_freqs) const;
const FTSLanguage& _getLanguageToUseV1(const BSONObj& userDoc) const;
static StatusWith<BSONObj> _fixSpecV1(const BSONObj& spec);
//
// Instance variables.
//
TextIndexVersion _textIndexVersion;
const FTSLanguage* _defaultLanguage;
std::string _languageOverrideField;
bool _wildcard;
// mapping : fieldname -> weight
Weights _weights;
// Prefix compound key - used to partition search index
std::vector<std::string> _extraBefore;
// Suffix compound key - used for covering index behavior
std::vector<std::string> _extraAfter;
};
} // namespace fts
} // namespace mongo
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