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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "zc4_posting_reader_base.h"
namespace search::diskindex {
/*
* Class used to read posting lists of type "Zc.4" and "Zc.5" (dynamic k).
*
* Common words have docid deltas and skip info separate from
* features. If "cheap" features are enabled then they are interleaved
* with docid deltas for quick access during sequential scan while the
* full features still remains separate.
*
* Rare words do not have skip info, and docid deltas and features are
* interleaved.
*/
template <bool bigEndian>
class Zc4PostingReader : public Zc4PostingReaderBase
{
protected:
using DecodeContext = bitcompression::FeatureDecodeContext<bigEndian>;
DecodeContext *_decodeContext;
void read_word_start();
public:
Zc4PostingReader(bool dynamic_k);
Zc4PostingReader(const Zc4PostingReader &) = delete;
Zc4PostingReader(Zc4PostingReader &&) = delete;
Zc4PostingReader &operator=(const Zc4PostingReader &) = delete;
Zc4PostingReader &operator=(Zc4PostingReader &&) = delete;
~Zc4PostingReader();
void read_doc_id_and_features(index::DocIdAndFeatures &features);
void set_counts(const index::PostingListCounts &counts);
void set_decode_features(DecodeContext *decode_features);
DecodeContext &get_decode_features() const { return *_decodeContext; }
};
extern template class Zc4PostingReader<false>;
extern template class Zc4PostingReader<true>;
}
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