Function extractChildren

packages/forms/signals/compat/src/api/extract.ts:120–163

(
  field: FieldTree<unknown>,
  value: unknown,
  filter?: ExtractFilter,
)

}

function extractChildren(
  field: FieldTree<unknown>,
  value: unknown,
  filter?: ExtractFilter,
): unknown {
  if (isArray(value)) {
    const record = field as unknown as Record<number, FieldTree<unknown>>;
    const arrayValue = value as readonly FieldTree<unknown>[];
    const result: unknown[] = new Array(arrayValue.length);
    let hasMatch = false;

    for (let i = 0; i < arrayValue.length; i++) {
      const child = record[i];

      const childResult = visitFieldTree(child, filter);
      if (childResult !== undefined) {
        hasMatch = true;
      }
      result[i] = childResult;
    }

    return hasMatch ? result : undefined;
  }

  if (isObject(value)) {
    const record = field as unknown as Record<string, unknown>;
    const objectValue = value as Record<string, unknown>;
    const entries = Object.keys(objectValue)
      .map<[string, FieldTree<unknown>] | undefined>((key) => {
        const child = record[key];
        return isFieldTreeNode(child) ? [key, child] : undefined;
      })
      .filter(isKeyedChild)
      .map(([key, child]) => {
        const childResult = visitFieldTree(child, filter);
        return childResult !== undefined ? ([key, childResult] as [string, unknown]) : undefined;
      })
      .filter((v) => v !== undefined);

    return entries.length ? Object.fromEntries(entries) : undefined;
  }

  return undefined;
}

function isFieldTreeNode(value: unknown): value is FieldTree<unknown> {
  return typeof value === 'function';