diff --git a/src/OpaqueVal.cc b/src/OpaqueVal.cc index feff4f3cc0..a42892e2b2 100644 --- a/src/OpaqueVal.cc +++ b/src/OpaqueVal.cc @@ -583,6 +583,11 @@ void BloomFilterVal::Clear() bloom_filter->Clear(); } +bool BloomFilterVal::Empty() const + { + return bloom_filter->Empty(); + } + BloomFilterVal* BloomFilterVal::Merge(const BloomFilterVal* x, const BloomFilterVal* y) { diff --git a/src/OpaqueVal.h b/src/OpaqueVal.h index 360bb69803..52c9583fc7 100644 --- a/src/OpaqueVal.h +++ b/src/OpaqueVal.h @@ -126,6 +126,7 @@ public: void Add(const Val* val); size_t Count(const Val* val) const; void Clear(); + bool Empty() const; static BloomFilterVal* Merge(const BloomFilterVal* x, const BloomFilterVal* y); diff --git a/src/probabilistic/BitVector.cc b/src/probabilistic/BitVector.cc index 98f008b24b..13cd1aa3bb 100644 --- a/src/probabilistic/BitVector.cc +++ b/src/probabilistic/BitVector.cc @@ -463,6 +463,14 @@ bool BitVector::Empty() const return bits.empty(); } +bool BitVector::AllZero() const + { + for ( size_t i = 0; i < bits.size(); ++i ) + if ( bits[i] ) + return false; + return true; + } + BitVector::size_type BitVector::FindFirst() const { return find_from(0); diff --git a/src/probabilistic/BitVector.h b/src/probabilistic/BitVector.h index 9eefe1b633..d9c55d53c6 100644 --- a/src/probabilistic/BitVector.h +++ b/src/probabilistic/BitVector.h @@ -253,6 +253,12 @@ public: */ bool Empty() const; + /** + * Checks whether all bits are 0. + * @return `true` iff all bits in all blocks are 0. + */ + bool AllZero() const; + /** * Finds the bit position of of the first 1-bit. * @return The position of the first bit that equals to one or `npos` if no diff --git a/src/probabilistic/BloomFilter.cc b/src/probabilistic/BloomFilter.cc index 132cf376ec..7f769cbf7c 100644 --- a/src/probabilistic/BloomFilter.cc +++ b/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)); } +bool BasicBloomFilter::Empty() const + { + return bits->AllZero(); + } + void BasicBloomFilter::Clear() { bits->Clear(); @@ -167,6 +172,11 @@ CountingBloomFilter::CountingBloomFilter(const Hasher* hasher, cells = new CounterVector(width, arg_cells); } +bool CountingBloomFilter::Empty() const + { + return cells->AllZero(); + } + void CountingBloomFilter::Clear() { cells->Clear(); diff --git a/src/probabilistic/BloomFilter.h b/src/probabilistic/BloomFilter.h index 2ab5b89941..b6cf18672f 100644 --- a/src/probabilistic/BloomFilter.h +++ b/src/probabilistic/BloomFilter.h @@ -47,6 +47,13 @@ public: return CountImpl((*hasher)(x)); } + /** + * Checks whether the Bloom filter is empty. + * + * @return `true` if the Bloom filter contains no elements. + */ + virtual bool Empty() const = 0; + /** * Removes all elements, i.e., resets all bits in the underlying bit vector. */ @@ -169,6 +176,7 @@ public: static size_t K(size_t cells, size_t capacity); // Overridden from BloomFilter. + virtual bool Empty() const; virtual void Clear(); virtual bool Merge(const BloomFilter* other); virtual BasicBloomFilter* Clone() const; @@ -207,6 +215,7 @@ public: CountingBloomFilter(const Hasher* hasher, size_t cells, size_t width); // Overridden from BloomFilter. + virtual bool Empty() const; virtual void Clear(); virtual bool Merge(const BloomFilter* other); virtual CountingBloomFilter* Clone() const; diff --git a/src/probabilistic/CounterVector.cc b/src/probabilistic/CounterVector.cc index 00fa7fb8c0..24c9ff3638 100644 --- a/src/probabilistic/CounterVector.cc +++ b/src/probabilistic/CounterVector.cc @@ -70,6 +70,11 @@ bool CounterVector::Decrement(size_type cell, count_type value) return carry; } +bool CounterVector::AllZero() const + { + return bits->AllZero(); + } + void CounterVector::Clear() { bits->Clear(); diff --git a/src/probabilistic/CounterVector.h b/src/probabilistic/CounterVector.h index 896f98ef1e..df6fc57ac2 100644 --- a/src/probabilistic/CounterVector.h +++ b/src/probabilistic/CounterVector.h @@ -77,6 +77,12 @@ public: */ count_type Count(size_type cell) const; + /** + * Checks whether all counters are 0. + * @return `true` iff all counters have the value 0. + */ + bool AllZero() const; + /** * Sets all counters to 0. */ diff --git a/src/probabilistic/bloom-filter.bif b/src/probabilistic/bloom-filter.bif index 9df168be0e..dd21688fdd 100644 --- a/src/probabilistic/bloom-filter.bif +++ b/src/probabilistic/bloom-filter.bif @@ -109,6 +109,9 @@ function bloomfilter_lookup%(bf: opaque of bloomfilter, x: any%): count %{ const BloomFilterVal* bfv = static_cast(bf); + if ( bfv->Empty() ) + return new Val(0, TYPE_COUNT); + if ( ! bfv->Type() ) reporter->Error("cannot perform lookup on untyped Bloom filter");