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Rework Bool_Array.

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This commit is contained in:
Bruno Haible
2002-10-30 12:36:40 +00:00
parent c7f32d582f
commit a07f46bd1d
6 changed files with 59 additions and 66 deletions
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39
src/bool-array.h
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@@ -21,25 +21,38 @@ You should have received a copy of the GNU General Public License
along with GNU GPERF; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Define and implement a simple boolean array abstraction,
uses an Iteration Numbering implementation to save on initialization time. */
#ifndef bool_array_h
#define bool_array_h 1
/* A Bool_Array instance is a bit array of fixed size, optimized for being
filled sparsely and cleared frequently. For example, when processing
tests/chill.gperf, the array will be:
- of size 15391,
- clear will be called 3509 times,
- set_bit will be called 300394 times.
With a conventional bit array implementation, clear would be too slow.
With a tree/hash based bit array implementation, set_bit would be slower. */
class Bool_Array
{
private:
static unsigned int *storage_array; /* Initialization of the index space. */
static unsigned int iteration_number; /* Keep track of the current iteration. */
static unsigned int size; /* Keep track of array size. */
public:
Bool_Array (void);
~Bool_Array (void);
static void init (unsigned int *buffer, unsigned int s);
static int find (int hash_value);
static void reset (void);
/* Initializes the bit array with room for s bits, numbered from 0 to s-1. */
Bool_Array (unsigned int s);
/* Frees this object. */
~Bool_Array (void);
/* Resets all bits to zero. */
void clear (void);
/* Sets the specified bit to one. Returns its previous value (0 or 1). */
int set_bit (unsigned int index);
private:
unsigned int size; /* Size of array. */
unsigned int iteration_number; /* Number of times clear() was called + 1. */
/* For each index, we store in storage_array[index] the iteration_number at
the time set_bit(index) was last called. */
unsigned int *storage_array;
};
#ifdef __OPTIMIZE__ /* efficiency hack! */