be/src/storage/index/inverted/query_v2/intersection.h

// Licensed to the Apache Software Foundation (ASF) under one
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// to you 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
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#pragma once

#include <vector>

#include "storage/index/inverted/query_v2/scorer.h"

namespace doris::segment_v2::inverted_index::query_v2 {

template <typename TDocSet, typename TOtherDocSet = ScorerPtr>
class Intersection;

template <typename TDocSet, typename TOtherDocSet>
using IntersectionPtr = std::shared_ptr<Intersection<TDocSet, TOtherDocSet>>;

template <typename TDocSet, typename TOtherDocSet>
class Intersection final : public Scorer {
public:
    Intersection(TDocSet left, TDocSet right, std::vector<TOtherDocSet> others, uint32_t num_docs);
    ~Intersection() override = default;

    template <typename T = TOtherDocSet>
    static std::enable_if_t<std::is_same_v<TDocSet, T>, IntersectionPtr<TDocSet, TDocSet>> create(
            std::vector<TDocSet>& docsets, uint32_t num_docs);

    uint32_t advance() override;
    uint32_t seek(uint32_t target) override;
    uint32_t doc() const override;
    uint32_t size_hint() const override;
    uint64_t cost() const override;
    uint32_t norm() const override;

    float score() override;

    template <typename T = TOtherDocSet>
    std::enable_if_t<std::is_same_v<TDocSet, T>, TDocSet&> docset_mut_specialized(size_t ord);

private:
    uint32_t intersect_from(uint32_t candidate);

    TDocSet _left;
    TDocSet _right;
    std::vector<TOtherDocSet> _others;

    uint32_t _num_docs = 0;
};

ScorerPtr make_intersect_scorers(std::vector<ScorerPtr> scorers, uint32_t num_docs);

template <typename TDocSet>
auto make_intersection(std::vector<TDocSet> docsets, uint32_t num_docs) {
    return Intersection<TDocSet, TDocSet>::create(docsets, num_docs);
}

} // namespace doris::segment_v2::inverted_index::query_v2