Using a Queue instead of a Recursion

Rather than calling functions recursively, you may at times want to use a Queue object that you can load with fresh tasks while you are unloading things that you have already processed.

Lee Holmes has recently posted the below sample which searches an entire filesystem folder tree without recursive calls:

# create a new queue
$dirs = [System.Collections.Queue]::new()

# add an initial path to the queue
# any folder path in the queue will later be processed
$dirs.Enqueue('c:windows')

# process all elements on the queue until all are taken
While ($current = $dirs.Dequeue())
{
    # find subfolders of current folder, and if present,
    # add them all to the queue
    try
    {
        foreach ($_ in [IO.Directory]::GetDirectories($current))
        {
                $dirs.Enqueue($_)
        }
    } catch {}

    try
    {
        # find all files in the folder currently processed
        [IO.Directory]::GetFiles($current, "*.exe") 
        [IO.Directory]::GetFiles($current, "*.ps1") 
    } catch { }
} 

The try-catch blocks are required because of the .NET methods used which raise exceptions when you do not have access privileges to files or folders.


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