TypedDataManager::getPropertyInstance

public TypedDataManager::getPropertyInstance(TypedDataInterface $object, $property_name, $value = NULL)

public function getPropertyInstance(TypedDataInterface $object, $property_name, $value = NULL) {
  // For performance, try to reuse existing prototypes instead of
  // constructing new objects when possible. A prototype is reused when
  // creating a data object:
  // - for a similar root object (same data type and settings),
  // - at the same property path under that root object.
  $root_definition = $object->getRoot()->getDataDefinition();
  // If the root object is a list, we want to look at the data type and the
  // settings of its item definition.
  if ($root_definition instanceof ListDataDefinition) {
    $root_definition = $root_definition->getItemDefinition();
  }

  // Root data type and settings.
  $parts[] = $root_definition->getDataType();
  if ($settings = $root_definition->getSettings()) {
    // Hash the settings into a string. crc32 is the fastest way to hash
    // something for non-cryptographic purposes.
    $parts[] = hash('crc32b', serialize($settings));
  }
  // Property path for the requested data object. When creating a list item,
  // use 0 in the key as all items look the same.
  $parts[] = $object->getPropertyPath() . '.' . (is_numeric($property_name) ? 0 : $property_name);
  $key = implode(':', $parts);

  // Create the prototype if needed.
  if (!isset($this->prototypes[$key])) {
    // Fetch the data definition for the child object from the parent.
    if ($object instanceof ComplexDataInterface) {
      $definition = $object->getDataDefinition()->getPropertyDefinition($property_name);
    }
    elseif ($object instanceof ListInterface) {
      $definition = $object->getItemDefinition();
    }
    else {
      throw new \InvalidArgumentException("The passed object has to either implement the ComplexDataInterface or the ListInterface.");
    }
    if (!$definition) {
      throw new \InvalidArgumentException("Property $property_name is unknown.");
    }
    // Create the prototype without any value, but with initial parenting
    // so that constructors can set up the objects correclty.
    $this->prototypes[$key] = $this->create($definition, NULL, $property_name, $object);
  }

  // Clone the prototype, update its parenting information, and assign the
  // value.
  $property = clone $this->prototypes[$key];
  $property->setContext($property_name, $object);
  if (isset($value)) {
    $property->setValue($value, FALSE);
  }
  return $property;
}