protected double[] fitness(final P param) {
final Predicate<? super EvolutionResult<G, N>> terminator = _terminator.apply(param);
final long start = System.currentTimeMillis();
final EvolutionResult<G, N> result =
_engine
.apply(param)
.stream()
.limit(terminator)
.collect(EvolutionResult.toBestEvolutionResult());
final long end = System.currentTimeMillis();
return new double[] {
result.getTotalGenerations(),
result.getBestFitness() != null
? result.getBestFitness().doubleValue()
: Double.NEGATIVE_INFINITY,
end - start
};
}