Add bloomfilter_clear() BiF.

src/probabilistic/BloomFilter.cc

@@ -74,6 +74,11 @@ size_t BasicBloomFilter::K(size_t cells, size_t capacity)
 	return std::ceil(frac * std::log(2));
 	}
 
+void BasicBloomFilter::Clear()
+	{
+	bits->Clear();
+	}
+
 BasicBloomFilter* BasicBloomFilter::Merge(const BasicBloomFilter* x,
                                           const BasicBloomFilter* y)
 	{
@@ -191,3 +196,8 @@ size_t CountingBloomFilter::CountImpl(const Hasher::digest_vector& h) const
 
 	return min;
 	}
+
+void CountingBloomFilter::Clear()
+	{
+	cells->Clear();
+	}

src/probabilistic/BloomFilter.h

@@ -47,6 +47,11 @@ public:
 		return CountImpl((*hasher)(x));
 		}
 
+	/**
+	 * Removes all elements, i.e., resets all bits in the underlying bit vector.
+	 */
+	virtual void Clear() = 0;
+
 	/**
 	 * Serializes the Bloom filter.
 	 *
@@ -147,6 +152,9 @@ public:
 	 */
 	static size_t K(size_t cells, size_t capacity);
 
+	// Overridden from BloomFilter.
+	virtual void Clear();
+
 	/**
 	 * Merges two basic Bloom filters.
 	 *
@@ -188,6 +196,9 @@ public:
 	 */
 	CountingBloomFilter(const Hasher* hasher, size_t cells, size_t width);
 
+	// Overridden from BloomFilter.
+	virtual void Clear();
+
 	/**
 	 * Merges two counting Bloom filters.
 	 *

src/probabilistic/CounterVector.cc

@@ -70,6 +70,11 @@ bool CounterVector::Decrement(size_type cell, count_type value)
 	return carry;
 	}
 
+void CounterVector::Clear()
+	{
+	bits->Clear();
+	}
+
 CounterVector::count_type CounterVector::Count(size_type cell) const
 	{
 	assert(cell < Size());

src/probabilistic/CounterVector.h

@@ -77,6 +77,11 @@ public:
 	 */
 	count_type Count(size_type cell) const;
 
+	/**
+	 * Sets all counters to 0.
+	 */
+	void Clear();
+
 	/**
 	 * Retrieves the number of cells in the storage.
 	 *

src/probabilistic/bloom-filter.bif

@@ -121,6 +121,22 @@ function bloomfilter_lookup%(bf: opaque of bloomfilter, x: any%): count
 	return new Val(0, TYPE_COUNT);
 	%}
 
+## Removes all elements from a Bloom filter. This function sets resets all bits
+## in the underlying bitvector to 0 but does not change the parameterization of
+## the Bloom filter, such as the element type and the hasher seed.
+##
+## bf: The Bloom filter handle.
+function bloomfilter_clear%(bf: opaque of bloomfilter%): any
+	%{
+	BloomFilterVal* bfv = static_cast<BloomFilterVal*>(bf);
+
+	if ( bfv->Type() ) // Untyped Bloom filters are already empty.
+		bfv->Clear();
+
+	return 0;
+	%}
+
+
 ## Merges two Bloom filters.
 ##
 ## bf1: The first Bloom filter handle.