added getMaxInsert()

src/main/java/org/apache/commons/collections4/bloomfilter/CountingBloomFilter.java

@@ -83,6 +83,57 @@ public interface CountingBloomFilter extends BloomFilter, CellProducer {
      */
     int getMaxCell();
 
+    /**
+     * Determines the maximum number of times the Bloom filter could have been inserted
+     * into this counting filter.
+     * @param bloomFilter the Bloom filter the check for.
+     * @return the maximum number of times the Bloom filter could have been inserted.
+     */
+    default int getMaxInsert(BloomFilter bloomFilter) {
+        return getMaxInsert((BitMapProducer) bloomFilter);
+    }
+
+    /**
+     * Determines the maximum number of times the IndexProducer could have been inserted
+     * into this counting filter.
+     * @param idxProducer the producer to drive the count check.
+     * @return the maximum number of times the IndexProducer could have been inserted.
+     */
+    default int getMaxInsert(IndexProducer idxProducer) {
+        return getMaxInsert( BitMapProducer.fromIndexProducer(idxProducer, getShape().getNumberOfBits()));
+    }
+
+    /**
+     * Determines the maximum number of times the Hasher could have been inserted into this
+     * counting filter.
+     * @param hasher the Hasher to provide the indices.
+     * @return the maximum number of times the hasher could have been inserted.
+     */
+    default int getMaxInsert(Hasher hasher) {
+        return getMaxInsert(hasher.indices(getShape()));
+    }
+
+    /**
+     * Determines the maximum number of times the BitMapProducer could hvae been insert into this
+     * counting filter.
+     * @param bitMapProducer the BitMapProducer to provide the indices.
+     * @return the maximum number of times the BitMapProducer could have been inserted.
+     */
+    default int getMaxInsert(BitMapProducer bitMapProducer) {
+        if (!contains(bitMapProducer)) {
+            return 0;
+        }
+        long[] bitMaps = bitMapProducer.asBitMapArray();
+        int[] max = { Integer.MAX_VALUE };
+        forEachCell((x, y) -> {
+            if ((bitMaps[BitMap.getLongIndex(x)] & BitMap.getLongBit(x)) != 0) {
+                max[0] = max[0] <= y ? max[0] : y;
+            }
+            return true;
+        });
+        return max[0];
+    }
+
     // Modification Operations
 
     /**

src/test/java/org/apache/commons/collections4/bloomfilter/AbstractCountingBloomFilterTest.java

@@ -293,4 +293,48 @@ public void testExcludesDuplicates() {
         assertEquals(0, bf1.cardinality());
         assertTrue(bf1.forEachCell((x, y) -> false), "Hasher in removes results in value not equal to 0");
     }
+
+    private void verifyMaxInsert( CountingBloomFilter bf, int from1, int from11) {
+        BloomFilter bfFrom0 = new DefaultBloomFilterTest.SparseDefaultBloomFilter(getTestShape());
+        bfFrom0.merge(new IncrementingHasher(0, 1));
+        BloomFilter bfFrom1 = new DefaultBloomFilterTest.SparseDefaultBloomFilter(getTestShape());
+        bfFrom1.merge(TestingHashers.FROM1);
+        BloomFilter bfFrom11 = new DefaultBloomFilterTest.SparseDefaultBloomFilter(getTestShape());
+        bfFrom11.merge(TestingHashers.FROM11);
+
+        assertEquals( 0, bf.getMaxInsert(new IncrementingHasher(0, 1)));
+        assertEquals( 0, bf.getMaxInsert(bfFrom0));
+        assertEquals( 0, bf.getMaxInsert((BitMapProducer) bfFrom0));
+        assertEquals( 0, bf.getMaxInsert((IndexProducer) bfFrom0));
+
+        assertEquals( from1, bf.getMaxInsert(TestingHashers.FROM1));
+        assertEquals( from1, bf.getMaxInsert(bfFrom1));
+        assertEquals( from1, bf.getMaxInsert((BitMapProducer) bfFrom1));
+        assertEquals( from1, bf.getMaxInsert((IndexProducer) bfFrom1));
+
+        assertEquals( from11, bf.getMaxInsert(TestingHashers.FROM11));
+        assertEquals( from11, bf.getMaxInsert(bfFrom11));
+        assertEquals( from11, bf.getMaxInsert((BitMapProducer) bfFrom11));
+        assertEquals( from11, bf.getMaxInsert((IndexProducer) bfFrom11));
+    }
+
+    @Test
+    public void testGetMaxInsert() {
+        CountingBloomFilter bf = createEmptyFilter(getTestShape());
+        verifyMaxInsert(bf, 0, 0);
+        bf.merge(TestingHashers.FROM1);
+        verifyMaxInsert(bf, 1, 0);
+        bf.merge(TestingHashers.FROM1);
+        verifyMaxInsert(bf, 2, 0);
+        bf.merge(TestingHashers.FROM11);
+        verifyMaxInsert(bf, 2, 1);
+        bf.remove(TestingHashers.FROM1);
+        verifyMaxInsert(bf, 1, 1);
+        // verify remove false positive works
+        // Incrementing hasher 5,1 spans the single count cells for both FROM1 and FROM11
+        assertEquals( 1, bf.getMaxInsert(new IncrementingHasher(5, 1)));
+        bf.remove(new IncrementingHasher(5, 1));
+        verifyMaxInsert(bf, 0, 0);
+        assertEquals( 0, bf.getMaxInsert(new IncrementingHasher(5, 1)));
+    }
 }