Multi-dimension rappor metrics

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 "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();
+namespace internal {
 
-  // Sets the Bloom filter bits to contain a single string.
-  void SetString(const std::string& str);
+// Converts a string to a bloom filter.
+// The first |bytes_size| bytes of |output| will be cleared, and have
+// |hash_function_count| bits set in it.  Which bits will be determined by
+// hashing |str| with a hash function using seeds in the range
+// |hash_seed_offset| to (|hash_seed_offset| + |hash_function_count|).
+void SetBloomBits(uint32_t bytes_size,
+                  uint32_t hash_function_count,
+                  uint32_t hash_seed_offset,
+                  const std::string& str,
+                  ByteVector* output);
 
-  // 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
 
 }  // namespace rappor
 
 #endif  // COMPONENTS_RAPPOR_BLOOM_FILTER_H_