Close Elements SGML to XML

CloseElements.ps1

function Close-Elements
{
    [CmdletBinding()]
    param(
        [Parameter(Mandatory, ParameterSetName="ReaderGiven", ValueFromPipeline, Position = 0)]
        [ValidateNotNullOrEmpty()]
        [System.Xml.XmlReader] $Reader,
        [Parameter(Mandatory, ParameterSetName="InPathGiven", ValueFromPipeline, Position = 0)]
        [ValidateNotNullOrEmpty()]
        [string] $InPath,
        [Parameter(Mandatory, ParameterSetName="WriterGiven", Position = 1)]
        [Parameter(ParameterSetName="InPathGiven", Position = 1)]
        [ValidateNotNullOrEmpty()]
        [System.Xml.XmlWriter] $Writer,
        [Parameter(Mandatory, ParameterSetName="OutPathGiven", Position = 1)]
        [Parameter(ParameterSetName="InPathGiven", Position = 1)]
        [ValidateNotNullOrEmpty()]
        [string] $OutPath
    )
    <# Thanks to Scott Hanselman http://www.hanselman.com/blog/postprocessing-autoclosed-sgml-tags-with-the-sgmlreader #>
    # $msgBody = $Reader.NameTable.Add('MSGBODY')
    if($PSCmdlet.ParameterSetName -eq "OutPathGiven")
    {
        $WriterSettings = [System.Xml.XmlWriterSettings]::new()
        $WriterSettings.Indent = $true
        $WriterSettings.IndentChars = ' '*4
        $WriterSettings.ConformanceLevel = [System.Xml.ConformanceLevel]::Fragment
        $Writer = [System.Xml.XmlWriter]::Create($OutPath, $WriterSettings)
    }
    if($PSCmdlet.ParameterSetName -eq "InPathGiven"){
        $Reader = [Sgml.SgmlReader]::Create($InPath)
    }
    $selfClosingTags = 'recbomba', 'recinser', 'trbomba', 'trinser', 'spanspec', 'colspec', 'mtoc', 'ptitle', 'pnote', 'usercomm', 'xmit', 'ctoc', 'sbeff', 'unitid', 'mtoc', 'mlep', 'clep', 'itemcol', 'mfmatr', 'sbtitle', 'sbdata', 'sbinfo', 'sblist'
    foreach ($tag in $selfClosingTags) {
        $Reader.NameTable.Add($tag)
    }
    $previousElement = $null
    $elementsWeAlreadyEnded = New-Object System.Collections.Stack
    while ($Reader.Read())
    {
        switch ($Reader.NodeType)
        {
            XmlNodeType.Element
            {
                $previousElement = $Reader.LocalName
                $Writer.WriteStartElement($Reader.LocalName)
                break
            }
            XmlNodeType.Text
            {
                if (-not [string]::IsNullOrEmpty($Reader.Value))
                {
                    $Writer.WriteString($Reader.Value.Trim())
                    if ($null -ne $previousElement -and $previousElement -notin $selfClosingTags)
                    {
                        $Writer.WriteEndElement()
                        $elementsWeAlreadyEnded.Push($previousElement)
                    }
                }
                else
                {
                    Write-Debug -Message "Empty text node"
                }
                break
            }
            XmlNodeType.EndElement
            {
                if ($elementsWeAlreadyEnded.Count -gt 0 -and $elementsWeAlreadyEnded.Peek() -eq $Reader.LocalName)
                {
                    # Next in the stack is the current end element, so pop it off
                    $elementsWeAlreadyEnded.Pop() | Out-Null
                }
                else
                {
                    $Writer.WriteEndElement()
                }
                break
            }
            default
            {
                $Writer.WriteNode($Reader, $false)
                break
            }
        }
    }
}