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// Copyright (C) 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "icing/join/aggregation-scorer.h"
#include <algorithm>
#include <memory>
#include <numeric>
#include <vector>
#include "icing/proto/search.pb.h"
#include "icing/scoring/scored-document-hit.h"
namespace icing {
namespace lib {
class CountAggregationScorer : public AggregationScorer {
public:
double GetScore(const ScoredDocumentHit& parent,
const std::vector<ScoredDocumentHit>& children) override {
return children.size();
}
};
class MinAggregationScorer : public AggregationScorer {
public:
double GetScore(const ScoredDocumentHit& parent,
const std::vector<ScoredDocumentHit>& children) override {
if (children.empty()) {
// Return 0 if there is no child document.
// For non-empty children with negative scores, they are considered "worse
// than" 0, so it is correct to return 0 for empty children to assign it a
// rank higher than non-empty children with negative scores.
return 0.0;
}
return std::min_element(children.begin(), children.end(),
[](const ScoredDocumentHit& lhs,
const ScoredDocumentHit& rhs) -> bool {
return lhs.score() < rhs.score();
})
->score();
}
};
class AverageAggregationScorer : public AggregationScorer {
public:
double GetScore(const ScoredDocumentHit& parent,
const std::vector<ScoredDocumentHit>& children) override {
if (children.empty()) {
// Return 0 if there is no child document.
// For non-empty children with negative scores, they are considered "worse
// than" 0, so it is correct to return 0 for empty children to assign it a
// rank higher than non-empty children with negative scores.
return 0.0;
}
return std::reduce(
children.begin(), children.end(), 0.0,
[](double prev, const ScoredDocumentHit& item) -> double {
return prev + item.score();
}) /
children.size();
}
};
class MaxAggregationScorer : public AggregationScorer {
public:
double GetScore(const ScoredDocumentHit& parent,
const std::vector<ScoredDocumentHit>& children) override {
if (children.empty()) {
// Return 0 if there is no child document.
// For non-empty children with negative scores, they are considered "worse
// than" 0, so it is correct to return 0 for empty children to assign it a
// rank higher than non-empty children with negative scores.
return 0.0;
}
return std::max_element(children.begin(), children.end(),
[](const ScoredDocumentHit& lhs,
const ScoredDocumentHit& rhs) -> bool {
return lhs.score() < rhs.score();
})
->score();
}
};
class SumAggregationScorer : public AggregationScorer {
public:
double GetScore(const ScoredDocumentHit& parent,
const std::vector<ScoredDocumentHit>& children) override {
return std::reduce(
children.begin(), children.end(), 0.0,
[](double prev, const ScoredDocumentHit& item) -> double {
return prev + item.score();
});
}
};
class DefaultAggregationScorer : public AggregationScorer {
public:
double GetScore(const ScoredDocumentHit& parent,
const std::vector<ScoredDocumentHit>& children) override {
return parent.score();
}
};
std::unique_ptr<AggregationScorer> AggregationScorer::Create(
const JoinSpecProto& join_spec) {
switch (join_spec.aggregation_scoring_strategy()) {
case JoinSpecProto::AggregationScoringStrategy::COUNT:
return std::make_unique<CountAggregationScorer>();
case JoinSpecProto::AggregationScoringStrategy::MIN:
return std::make_unique<MinAggregationScorer>();
case JoinSpecProto::AggregationScoringStrategy::AVG:
return std::make_unique<AverageAggregationScorer>();
case JoinSpecProto::AggregationScoringStrategy::MAX:
return std::make_unique<MaxAggregationScorer>();
case JoinSpecProto::AggregationScoringStrategy::SUM:
return std::make_unique<SumAggregationScorer>();
case JoinSpecProto::AggregationScoringStrategy::NONE:
// No aggregation strategy means using parent document score, so fall
// through to return DefaultAggregationScorer.
[[fallthrough]];
default:
return std::make_unique<DefaultAggregationScorer>();
}
}
} // namespace lib
} // namespace icing
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