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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chromeos/ash/components/string_matching/acronym_matcher.h"
#include <cstddef>
#include <string>
#include "base/i18n/case_conversion.h"
#include "chromeos/ash/components/string_matching/tokenized_string.h"
namespace ash::string_matching {
namespace {
using acronym_matcher_constants::kIsFrontOfTokenCharScore;
using acronym_matcher_constants::kIsPrefixCharScore;
using acronym_matcher_constants::kNoMatchScore;
} // namespace
// AcronymMatcher:
//
// The factors below are applied when the current char of query matches
// the current char of the text to be matched. Different factors are chosen
// based on where the match happens:
//
// 1) `kIsPrefixCharScore` is used when we match the first char of the query to
// the first char of the text
//
// 2) `kIsFrontOfTokenCharScore` will be used if the first char of the token
// matches the current char of the query in all other cases.
//
// Examples:
//
// For text: 'Google Chrome'.
//
// Query 'gc' would use kIsPrefixCharScore for 'g' and
// kIsFrontOfTokenCharScore for 'c'.
// kNoMatchScore is a relevance score that represents no match.
AcronymMatcher::AcronymMatcher(const TokenizedString& query,
const TokenizedString& text) {
query_ = base::i18n::ToLower(query.text());
for (auto token : text.tokens()) {
text_acronym_.push_back(token[0]);
}
text_mapping_ = text.mappings();
}
AcronymMatcher::~AcronymMatcher() = default;
double AcronymMatcher::CalculateRelevance() {
auto found_index = text_acronym_.find(query_);
if (found_index == std::u16string::npos) {
return kNoMatchScore;
}
double relevance = kIsFrontOfTokenCharScore * query_.size();
if (found_index == 0) {
relevance += kIsPrefixCharScore - kIsFrontOfTokenCharScore;
}
// update the |hits_| if there is a match.
for (size_t i = 0; i < query_.size(); i++) {
size_t start_pos = text_mapping_[found_index + i].start();
hits_.emplace_back(start_pos, start_pos + 1);
}
return relevance;
}
} // namespace ash::string_matching
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