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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "dfa_string_comparator.h"
#include <vespa/vespalib/datastore/atomic_entry_ref.h>
#include <vespa/vespalib/fuzzy/levenshtein_dfa.h>
#include <iostream>
namespace search::attribute {
/**
* Class that uses a LevenshteinDfa to fuzzy match a target word against words in a dictionary.
*
* The dictionary iterator is advanced based on the successor string from the DFA
* each time the candidate word is _not_ a match.
*/
class DfaFuzzyMatcher {
private:
vespalib::fuzzy::LevenshteinDfa _dfa;
std::vector<uint32_t> _successor;
std::vector<uint32_t> _prefix;
uint32_t _prefix_size;
bool _cased;
const char* skip_prefix(const char* word) const;
public:
DfaFuzzyMatcher(std::string_view target, uint8_t max_edits, uint32_t prefix_size, bool cased, vespalib::fuzzy::LevenshteinDfa::DfaType dfa_type);
~DfaFuzzyMatcher();
bool is_match(const char *word) const;
/*
* If prefix size is nonzero then this variant of is_match()
* should only be called with words that starts with the extracted
* prefix of the target word.
*
* Caller must position iterator at right location using lower bound
* functionality in the dictionary.
*/
template <typename DictionaryConstIteratorType>
bool is_match(const char* word, DictionaryConstIteratorType& itr, const DfaStringComparator::DataStoreType& data_store) {
if (_prefix_size > 0) {
word = skip_prefix(word);
if (_prefix.size() < _prefix_size) {
if (*word == '\0') {
return true;
}
_successor.resize(_prefix.size());
_successor.emplace_back(1);
} else {
_successor.resize(_prefix.size());
auto match = _dfa.match(word, _successor);
if (match.matches()) {
return true;
}
}
} else {
_successor.clear();
auto match = _dfa.match(word, _successor);
if (match.matches()) {
return true;
}
}
DfaStringComparator cmp(data_store, _successor);
itr.seek(vespalib::datastore::AtomicEntryRef(), cmp);
return false;
}
};
}
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