Function getTopologicalSortAndRecipientCounts

tfjs-layers/src/engine/executor.ts:395–438

* Sort the `SymbolicTensor`s topologically, for an array of fetches. * * This function calls getTopologicalSortAndRecipientCountsForOneFetch and * merges their results. * * @param fetch The array of fetches requested. Must be a non-empty array. * @param feedDict The dictionary of fed values.

(
    fetches: SymbolicTensor[], feedDict: FeedDict)

 *   recipientCounts: Recipient counts for all SymbolicTensors in `sorted`.
 */
function getTopologicalSortAndRecipientCounts(
    fetches: SymbolicTensor[], feedDict: FeedDict):
    {sorted: SymbolicTensor[], recipientCounts: RecipientCounts} {
  util.assert(
      fetches != null && fetches.length > 0,
      () => `Expected at least one fetch, got none`);

  let finalSorted: SymbolicTensor[] = [];
  let finalRecipientMap: RecipientMap = {};
  if (fetches.length === 1) {
    // Special-casing 1 fetch for efficiency.
    const out =
        getTopologicalSortAndRecipientCountsForOneFetch(fetches[0], feedDict);
    finalSorted = out.sorted;
    finalRecipientMap = out.recipientMap;
  } else {
    const visited = new Set<string>();
    for (const fetch of fetches) {
      const {sorted, recipientMap} =
          getTopologicalSortAndRecipientCountsForOneFetch(fetch, feedDict);

      // Merge sorted SymbolicTensor Arrays.
      for (const symbolicTensor of sorted) {
        if (!visited.has(symbolicTensor.name)) {
          finalSorted.push(symbolicTensor);
          visited.add(symbolicTensor.name);
        }
      }

      // Merge recipient maps.
      for (const name in recipientMap) {
        if (finalRecipientMap[name] == null) {
          finalRecipientMap[name] = new Set<string>();
        }
        recipientMap[name].forEach(
            recipient => finalRecipientMap[name].add(recipient));
      }
    }
  }
  return {
    sorted: finalSorted,
    recipientCounts: recipientMap2Counts(finalRecipientMap)
  };
}

function recipientMap2Counts(recipientMap: RecipientMap): RecipientCounts {
  const recipientCounts: RecipientCounts = {};