| // Copyright 2010-2015, Google Inc. |
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| |
| #ifndef MOZC_STORAGE_LOUDS_SIMPLE_SUCCINCT_BIT_VECTOR_INDEX_H_ |
| #define MOZC_STORAGE_LOUDS_SIMPLE_SUCCINCT_BIT_VECTOR_INDEX_H_ |
| |
| #include <vector> |
| #include "base/port.h" |
| |
| namespace mozc { |
| namespace storage { |
| namespace louds { |
| |
| // This is simple(naive) C++ implementation of succinct bit vector. |
| class SimpleSuccinctBitVectorIndex { |
| public: |
| // The default chunk_size is 32. |
| SimpleSuccinctBitVectorIndex() |
| : data_(NULL), length_(0), chunk_size_(32) { |
| } |
| |
| // chunk_size is in bytes, and must be greater than or equal to 4 |
| // and power of 2, at the moment, although we may relax the restriction |
| // in future if necessary. |
| explicit SimpleSuccinctBitVectorIndex(int chunk_size) |
| : data_(NULL), length_(0), chunk_size_(chunk_size) { |
| } |
| |
| // Initializes the index. This class doesn't have the ownership of the memory |
| // pointed by data, so it is caller's responsibility to manage its life time. |
| // The 'data' needs to be aligned to 32-bits. |
| void Init(const uint8 *data, int length); |
| |
| // Resets the internal state, especially releases the allocated memory |
| // for the index used internally. |
| void Reset(); |
| |
| // Returns the bit at the index in data. The index in a byte is as follows; |
| // MSB|XXXXXXXX|LSB |
| // 76543210 |
| int Get(int index) const { |
| return (data_[index / 8] >> (index % 8)) & 1; |
| } |
| |
| // Returns the number of 0-bit in [0, n) bits of data. |
| int Rank0(int n) const { |
| return n - Rank1(n); |
| } |
| |
| // Returns the number of 1-bit in [0, n) bits of data. |
| int Rank1(int n) const; |
| |
| // Returns the position of n-th 0-bit on the data. (n is 1-origin). |
| // Returned index is 0-origin. |
| int Select0(int n) const; |
| |
| // Returns the position of n-th 1-bit in the data. (n is 1-origin). |
| // Returned index is 0-origin. |
| int Select1(int n) const; |
| |
| private: |
| const uint8 *data_; |
| int length_; |
| int chunk_size_; |
| |
| // TODO(hidehiko): Create two-level index for more performance. |
| vector<int> index_; |
| |
| DISALLOW_COPY_AND_ASSIGN(SimpleSuccinctBitVectorIndex); |
| }; |
| |
| } // namespace louds |
| } // namespace storage |
| } // namespace mozc |
| |
| #endif // MOZC_STORAGE_LOUDS_SIMPLE_SUCCINCT_BIT_VECTOR_INDEX_H_ |