public static async IAsyncEnumerable <IEnumerable <FileInfo> > LoadFilesAsync([NotNull] IEnumerable <DirectoryInfo> directories, [NotNull] string searchPattern, SearchOption searchOption)
{
directories = directories.ArgumentNotNull();
searchPattern = searchPattern.ArgumentNotNull();
if (searchOption.CheckIsDefined() is false)
{
searchOption = SearchOption.TopDirectoryOnly;
}
var options = new EnumerationOptions()
{
IgnoreInaccessible = true
};
if (searchOption == SearchOption.AllDirectories)
{
options.RecurseSubdirectories = true;
}
var validDirectories = directories.Where(directory => directory.Exists).Select(directory => directory).ToList();
for (var directoryCount = 0; directoryCount < validDirectories.FastCount(); directoryCount++)
{
IEnumerable <FileInfo> files = await Task.Run(() =>
{
return(validDirectories[directoryCount].EnumerateFiles(searchPattern, options));
}).ConfigureAwait(false);
yield return(files);
}
}
