src/base/bitarray.h

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#ifndef MOZC_BASE_BITARRAY_H_
#define MOZC_BASE_BITARRAY_H_

#include <cstring>   // memset

#include "base/port.h"
#include "base/scoped_ptr.h"

namespace mozc {

class BitArray {
 public:
  // Specify the size of bit vector
  explicit BitArray(uint32 size) : array_(new uint32[1 + (size >> 5)]),
                                   size_(size) {
    memset(reinterpret_cast<char *>(array_.get()), 0, 4 * (1 + (size >> 5)));
  }

  ~BitArray() {}

  // Gets true/false of |index|
  bool get(uint32 index) const {
    return static_cast<bool>(
        (array_[(index >> 5)] >> (index & 0x0000001F)) & 0x00000001);
  }

  // Sets the bit at |index| to true.
  void set(uint32 index) {
    array_[(index >> 5)] |= 0x00000001 << (index & 0x0000001F);
  }

  // Sets the bit at |index| to false.
  void clear(uint32 index) {
    array_[(index >> 5)] &= ~(0x00000001 << (index & 0x0000001F));
  }

  // Returns the body of bit vector.
  const char *array() const {
    return reinterpret_cast<const char *>(array_.get());
  }

  // Returns the required buffer size for saving the bit vector.
  size_t array_size() const {
    return 4 * (1 + (size_ >> 5));
  }

  // Returns the number of bit(s).
  size_t size() const {
    return size_;
  }

  // Immutable accessor.
  static bool GetValue(const char *array, uint32 index) {
    const uint32 *uarray = reinterpret_cast<const uint32 *>(array);
    return static_cast<bool>(
        (uarray[(index >> 5)] >> (index & 0x0000001F)) & 0x00000001);
  }

 private:
  scoped_ptr<uint32[]> array_;
  const size_t size_;

  DISALLOW_COPY_AND_ASSIGN(BitArray);
};

}  // namespace mozc

#endif  // MOZC_BASE_BITARRAY_H_