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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_RAPPOR_BLOOM_FILTER_H_
#define COMPONENTS_RAPPOR_BLOOM_FILTER_H_
#include <string>
#include "base/basictypes.h"
#include "base/macros.h"
#include "components/rappor/byte_vector_utils.h"
namespace rappor {
// BloomFilter is a simple Bloom filter for keeping track of a set of strings.
class BloomFilter {
public:
// Constructs a BloomFilter using |bytes_size| bytes of Bloom filter bits,
// and |hash_function_count| hash functions to set bits in the filter. The
// hash functions will be generated by using seeds in the range
// |hash_seed_offset| to (|hash_seed_offset| + |hash_function_count|).
BloomFilter(uint32_t bytes_size,
uint32_t hash_function_count,
uint32_t hash_seed_offset);
~BloomFilter();
// Sets the Bloom filter bits to contain a single string.
void SetString(const std::string& str);
// Returns the current value of the Bloom filter's bit array.
const ByteVector& bytes() const { return bytes_; };
// Sets bytes for testing purposes.
void SetBytesForTesting(const ByteVector& bytes);
private:
// Stores the byte array of the Bloom filter.
ByteVector bytes_;
// The number of bits to set for each string added.
uint32_t hash_function_count_;
// A number add to a hash function index to get a seed for that hash function.
uint32_t hash_seed_offset_;
DISALLOW_COPY_AND_ASSIGN(BloomFilter);
};
namespace internal {
// A function for getting bloom filters less than or equal to 64 bits.
uint64_t GetBloomBits(uint32_t bytes_size,
uint32_t hash_function_count,
uint32_t hash_seed_offset,
const std::string& str);
} // namespace internal
} // namespace rappor
#endif // COMPONENTS_RAPPOR_BLOOM_FILTER_H_
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