Show-Tree.ps1

Show-Tree.ps1

using namespace System.Collections.Generic
function Show-Tree
{
# .SYNOPSIS

#     Print a tree given a key property and parent property
#
# .PARAMETER InputObject
#
#     The object to print.
#
# .PARAMETER KeyProperty
#
#     The property name that is unique in each value in InputObject
#
# .PARAMETER ParentProperty
#
#     The property name of the value that refers to the parent
#
# .PaRAMETER Formatter
#
#     An option script block to format the output.
#
# .EXAMPLE
#
#     Get-CimInstance Win32_Process |
#         print_tree.ps1 -KeyProperty ProcessId -ParentProperty ParentProcessId -Formatter { param($o) "{0} ({1})" -f $o.Name, $o.ProcessId }
#
    param(
        [Parameter(ValueFromPipeline)]
        [object[]]$InputObject,

        [Parameter(Mandatory)]
        [string] $KeyProperty,

        [Parameter(Mandatory)]
        [string] $ParentProperty,

        [Parameter()]
        [scriptblock] $Formatter,

        [Parameter()]
        [string]$IndentString = "| "
    )

    begin
    {
        class Node
        {
            $Key
            [List[Node]]$Children = [List[Node]]::new()
            $Value
        }


        $root = [List[Node]]::new()
        $nodeLookup = @{}
    }

    process
    {
        foreach ($obj in $InputObject)
        {
            $node = [Node]@{Key = $obj.$KeyProperty; Value = $obj}
            if ($nodeLookup[$node.Key])
            {
                Write-Warning "Ignoring duplicate: $obj"
            }
            else
            {
                $nodeLookup[$node.Key] =  $node
            }

            $parentPropertyValue = $obj.$ParentProperty
            $parent = if ($parentPropertyValue) { $nodeLookup[$parentPropertyValue] } else { $null }
            if (!$parent)
            {
                $root.Add($node)
            }
            else
            {
                $parent.Children.Add($node)
            }
        }
    }

    end
    {
        function PrintNode([Node]$node, [string]$Indent)
        {
            $formatted = if ($Formatter) {
                & $Formatter $node.Value
            } else {
                ($node.Value | Format-Wide | Out-String).Trim()
            }

            "{0}{1}" -f $indent, $formatted
            $Indent += $IndentString
            foreach ($n in $node.Children)
            {
                PrintNode $n $Indent
            }
        }

        foreach ($n in $root)
        {
            PrintNode $n ''
        }
    }
}