137 lines
2.7 KiB
C
137 lines
2.7 KiB
C
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///////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 1998-1999, Microsoft Corp. All rights reserved.
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//
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// FILE
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//
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// BitVec.h
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//
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// SYNOPSIS
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//
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// This file implements the class BitVector
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//
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// MODIFICATION HISTORY
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//
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// 02/09/1998 Original version.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef _BITVEC_H_
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#define _BITVEC_H_
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///////////////////////////////////////////////////////////////////////////////
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//
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// CLASS
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//
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// BitVector
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//
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// DESCRIPTION
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//
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// Very simple bit vector optimized for use by the CSimpleTable class.
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//
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///////////////////////////////////////////////////////////////////////////////
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class BitVector
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{
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public:
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// Type used to store bits.
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typedef unsigned long Bucket;
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BitVector()
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: numBuckets(0), numSet(0), bits(NULL) { }
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~BitVector()
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{
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delete[] bits;
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}
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// Returns true if any bits are set.
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bool any() const
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{
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return numSet != 0;
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}
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// Returns the number of bits set.
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size_t count() const
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{
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return numSet;
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}
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// Returns true if no bits are set.
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bool none() const
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{
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return numSet == 0;
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}
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// Clears all bits.
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void reset()
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{
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if (any())
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{
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memset(bits, 0, numBuckets * sizeof(Bucket));
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numSet = 0;
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}
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}
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// Resizes the bitvector to have room for at least 'n' bits. Also clears
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// any existing bits.
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bool resize(size_t n)
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{
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size_t newBuckets = (n + sizeof(Bucket) - 1)/sizeof(Bucket);
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if (newBuckets >= numBuckets)
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{
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numBuckets = newBuckets;
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delete[] bits;
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bits = new (std::nothrow) Bucket[numBuckets];
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if ( !bits )
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{
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return false;
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}
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}
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memset(bits, 0, numBuckets * sizeof(Bucket));
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numSet = 0;
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return true;
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}
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// Sets the given bit.
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void set(size_t i)
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{
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if (!test(i))
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{
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++numSet;
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getBucket(i) |= getBit(i);
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}
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}
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// Returns true if the given bit is set.
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bool test(size_t i) const
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{
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return (getBucket(i) & getBit(i)) != 0;
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}
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protected:
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// Return the bit for a given index.
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static Bucket getBit(size_t i)
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{ return (Bucket)1 << (i % sizeof(Bucket)); }
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// Return the bucket for a given index.
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Bucket& getBucket(size_t i) const
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{ return bits[i / sizeof(Bucket)]; }
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size_t numBuckets; // Number of bit buckets.
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size_t numSet; // Number of bits currently set.
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Bucket* bits; // Array of bit buckets.
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// Not implemented.
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BitVector(const BitVector&);
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BitVector& operator=(const BitVector&);
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};
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#endif // _BITVEC_H_
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