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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_UKM_BITSET_H_
#define COMPONENTS_UKM_BITSET_H_
#include <cstdint>
#include <string>
#include <vector>
#include "base/component_export.h"
namespace ukm {
// A custom bitset class used to keep track of web feature usage across
// sources in UKM. `std::bitset<>` and `base::EnumSet<>` are intentionally not
// used because they do not provide the flexibility needed to efficiently
// serialize/deserialize the set.
class COMPONENT_EXPORT(UKM_RECORDER) BitSet {
public:
// Creates an empty BitSet with specified `set_size`.
explicit BitSet(size_t set_size);
// Constructor to recreate a serialized bitset (provided as `data`).
BitSet(size_t set_size, std::string_view data);
BitSet(const BitSet&) = delete;
BitSet& operator=(const BitSet&) = delete;
~BitSet();
// Adds the given `index` to the bitset.
void Add(size_t index);
// Returns whether the given `index` is present in the bitset.
bool Contains(size_t index) const;
// Serializes `this` and returns the compressed value. The bitset can be
// recreated with the `BitSet(size_t, std::string_view)` constructor.
std::string Serialize() const;
size_t set_size() const { return set_size_; }
private:
// Returns which element `index` maps to in `bitset_`.
size_t ToInternalIndex(size_t index) const;
// Returns which bit `index` maps to given a certain `bitset_` element.
uint8_t ToBitmask(size_t index) const;
const size_t set_size_;
std::vector<uint8_t> bitset_;
};
} // namespace ukm
#endif // COMPONENTS_UKM_BITSET_H_
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