80 lines
2.5 KiB
C++
80 lines
2.5 KiB
C++
/* This may look like C code, but it is really -*- C++ -*- */
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/* Simple lookup table abstraction implemented as an Iteration Number Array.
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Copyright (C) 1989-1998, 2002 Free Software Foundation, Inc.
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Written by Douglas C. Schmidt <schmidt@ics.uci.edu>
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and Bruno Haible <bruno@clisp.org>.
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This file is part of GNU GPERF.
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GNU GPERF is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU GPERF is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; see the file COPYING.
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If not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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#ifndef bool_array_h
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#define bool_array_h 1
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/* A Bool_Array instance is a bit array of fixed size, optimized for being
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filled sparsely and cleared frequently. For example, when processing
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tests/chill.gperf, the array will be:
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- of size 15391,
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- clear will be called 3509 times,
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- set_bit will be called 300394 times.
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With a conventional bit array implementation, clear would be too slow.
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With a tree/hash based bit array implementation, set_bit would be slower. */
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class Bool_Array
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{
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public:
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/* Initializes the bit array with room for SIZE bits, numbered from
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0 to SIZE-1. */
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Bool_Array (unsigned int size);
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/* Frees this object. */
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~Bool_Array ();
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/* Resets all bits to zero. */
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void clear ();
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/* Sets the specified bit to true.
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Returns its previous value (false or true). */
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bool set_bit (unsigned int index);
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private:
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/* Size of array. */
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unsigned int const _size;
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/* Current iteration number. Always nonzero. Starts out as 1, and is
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incremented each time clear() is called. */
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unsigned int _iteration_number;
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/* For each index, we store in storage_array[index] the iteration_number at
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the time set_bit(index) was last called. */
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unsigned int * const _storage_array;
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};
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#ifdef __OPTIMIZE__ /* efficiency hack! */
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#include <stdio.h>
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#include <string.h>
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#include "options.h"
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#define INLINE inline
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#include "bool-array.icc"
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#undef INLINE
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#endif
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#endif
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