RAPPOR implementation

components/rappor/bloom_filter.h

+// 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 "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();
+
+  // Add a single string to the Bloom filter.
+  void AddString(const std::string& str);
+
+  // Returns the current value of the Bloom filter's bit array.
+  const ByteVector& bytes() const { return 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 rappor
+
+#endif  // COMPONENTS_RAPPOR_BLOOM_FILTER_H_