Function bloomAdd

packages/core/src/render3/di.ts:152–184

(
  injectorIndex: number,
  tView: TView,
  type: ProviderToken<any> | string,
)

 * @param type The directive token to register
 */
export function bloomAdd(
  injectorIndex: number,
  tView: TView,
  type: ProviderToken<any> | string,
): void {
  ngDevMode && assertEqual(tView.firstCreatePass, true, 'expected firstCreatePass to be true');
  let id: number | undefined;
  if (typeof type === 'string') {
    id = type.charCodeAt(0) || 0;
  } else if (type.hasOwnProperty(NG_ELEMENT_ID)) {
    id = (type as any)[NG_ELEMENT_ID];
  }

  // Set a unique ID on the directive type, so if something tries to inject the directive,
  // we can easily retrieve the ID and hash it into the bloom bit that should be checked.
  if (id == null) {
    id = (type as any)[NG_ELEMENT_ID] = nextNgElementId++;
  }

  // We only have BLOOM_SIZE (256) slots in our bloom filter (8 buckets * 32 bits each),
  // so all unique IDs must be modulo-ed into a number from 0 - 255 to fit into the filter.
  const bloomHash = id & BLOOM_MASK;

  // Create a mask that targets the specific bit associated with the directive.
  // JS bit operations are 32 bits, so this will be a number between 2^0 and 2^31, corresponding
  // to bit positions 0 - 31 in a 32 bit integer.
  const mask = 1 << bloomHash;

  // Each bloom bucket in `tData` represents `BLOOM_BUCKET_BITS` number of bits of `bloomHash`.
  // Any bits in `bloomHash` beyond `BLOOM_BUCKET_BITS` indicate the bucket offset that the mask
  // should be written to.
  (tView.data as number[])[injectorIndex + (bloomHash >> BLOOM_BUCKET_BITS)] |= mask;
}

/**
 * Creates (or gets an existing) injector for a given element or container.