Function concatFactory

src/Operations.js:690–722

(collection, values)

}

export function concatFactory(collection, values) {
  const isKeyedCollection = isKeyed(collection);
  const iters = [collection]
    .concat(values)
    .map((v) => {
      if (!isCollection(v)) {
        v = isKeyedCollection
          ? keyedSeqFromValue(v)
          : indexedSeqFromValue(Array.isArray(v) ? v : [v]);
      } else if (isKeyedCollection) {
        v = KeyedCollection(v);
      }
      return v;
    })
    .filter((v) => v.size !== 0);

  if (iters.length === 0) {
    return collection;
  }

  if (iters.length === 1) {
    const singleton = iters[0];
    if (
      singleton === collection ||
      (isKeyedCollection && isKeyed(singleton)) ||
      (isIndexed(collection) && isIndexed(singleton))
    ) {
      return singleton;
    }
  }

  return new ConcatSeq(iters);
}

export function flattenFactory(collection, depth, useKeys) {
  const flatSequence = makeSequence(collection);