default int estimateIntersection()

in src/main/java/org/apache/commons/collections4/bloomfilter/BloomFilter.java [148:175]

• 24 lines of code
• 8 McCabe index (conditional complexity)

    default int estimateIntersection(final BloomFilter<?> other) {
        Objects.requireNonNull(other, "other");
        final double eThis = getShape().estimateN(cardinality());
        final double eOther = getShape().estimateN(other.cardinality());
        if (Double.isInfinite(eThis) && Double.isInfinite(eOther)) {
            // if both are infinite the union is infinite and we return Integer.MAX_VALUE
            return Integer.MAX_VALUE;
        }
        long estimate;
        // if one is infinite the intersection is the other.
        if (Double.isInfinite(eThis)) {
            estimate = Math.round(eOther);
        } else if (Double.isInfinite(eOther)) {
            estimate = Math.round(eThis);
        } else {
            final T union = this.copy();
            union.merge(other);
            final double eUnion = getShape().estimateN(union.cardinality());
            if (Double.isInfinite(eUnion)) {
                throw new IllegalArgumentException("The estimated N for the union of the filters is infinite");
            }
            // maximum estimate value using integer values is: 46144189292 thus
            // eThis + eOther cannot overflow the long value.
            estimate = Math.round(eThis + eOther - eUnion);
            estimate = estimate < 0 ? 0 : estimate;
        }
        return estimate > Integer.MAX_VALUE ? Integer.MAX_VALUE : (int) estimate;
    }