> */ class FrequencyGenerator implements Generator { private $generators; public function __construct(array $generatorsWithFrequency) { if (empty($generatorsWithFrequency)) { throw new InvalidArgumentException( 'Cannot choose from an empty array of generators' ); } $this->generators = array_reduce( $generatorsWithFrequency, function ($generators, $generatorWithFrequency) { list($frequency, $generator) = $generatorWithFrequency; $frequency = $this->ensureIsFrequency($generatorWithFrequency[0]); $generator = ensureIsGenerator($generatorWithFrequency[1]); if ($frequency > 0) { $generators[] = [ 'generator' => $generator, 'frequency' => $frequency, ]; } return $generators; }, [] ); } public function __invoke($size, RandomRange $rand) { list($index, $generator) = $this->pickFrom($this->generators, $rand); $originalValue = $generator->__invoke($size, $rand); return GeneratedValueSingle::fromValueAndInput( $originalValue->unbox(), [ 'value' => $originalValue, 'generator' => $index, ], 'frequency' ); } public function shrink(GeneratedValue $element) { $input = $element->input(); $originalGeneratorIndex = $input['generator']; $shrinkedValue = $this->generators[$originalGeneratorIndex]['generator']->shrink($input['value']); // TODO: take advantage of multiple shrinking return GeneratedValueSingle::fromValueAndInput( $shrinkedValue->unbox(), [ 'value' => $shrinkedValue, 'generator' => $originalGeneratorIndex, ], 'frequency' ); } /** * @return array two elements: index and Generator object */ private function pickFrom($generators, RandomRange $rand) { $acc = 0; $frequencies = $this->frequenciesFrom($generators); $random = $rand->rand(1, array_sum($frequencies)); foreach ($generators as $index => $generator) { $acc += $generator['frequency']; if ($random <= $acc) { return [$index, $generator['generator']]; } } throw new \Exception( 'Unable to pick a generator with frequencies: ' . var_export($frequencies, true) ); } private function frequenciesFrom($generators) { return array_map( function ($generatorWithFrequency) { return $generatorWithFrequency['frequency']; }, $generators ); } private function ensureIsFrequency($frequency) { if (!is_int($frequency) || $frequency < 0) { throw new InvalidArgumentException( 'Frequency must be an integer greater or equal than 0, given: ' . var_export($frequency, true) ); } return $frequency; } }