Show-PipelineCaller.ps1

function Show-Pipelinecaller {
    <#
    .SYNOPSIS
    Returns an object with the command and resolved command in a pipeline or input line.
    @trackd
    .PARAMETER Line
    the line to parse
    .PARAMETER PassThru
    just passthrough for objects, not sure how useful that is.
    .EXAMPLE
    $a = gci | % fullname | gi | Show-PipelineCaller -Verbose
    $a | % fullname | gi | Show-PipelineCaller -Verbose -all
    .EXAMPLE
    could be used to track down the source of a command in a pipeline from a function
    Show-Pipelinecaller -Line $MyInvocation.Line
    .EXAMPLE
    Show-Pipelinecaller -line 'gci -recurse | gi | select -Last 1 | NotAnActualcmd -param stuff -t v'
    .EXAMPLE
    Show-Pipelinecaller -line '$stevejobs = gci .\apple -recurse | gi | select -first 1' -Verbose
    #>
    [cmdletbinding()]
    param(
        [Parameter(Position = 0)]
        [string]
        $Line,
        [Parameter(ValueFromPipeline)]
        $InputObject,
        [Switch]
        $Passthru
    )
    begin {
        Write-Verbose "Command: $($MyInvocation.MyCommand.Name) Param: $($PSBoundParameters.GetEnumerator())"
        $i = 1
    }
    process {
        if ($Passthru) {
            # not sure how useful this is, will get mixed up with the command names.
            $InputObject
        }
    }
    end {
        if ($MyInvocation.ExpectingInput) {
            $cmdline = $MyInvocation.Line
        }
        else {
            $cmdline = $Line
        }
        if ($cmdline) {
            Write-Verbose $cmdline
            $ast = ([System.Management.Automation.Language.Parser]::ParseInput($cmdline, [ref]$null, [ref]$null)).EndBlock.Statements[0]
            if ($ast.left) {
                # when the pipeline is started by a variable assignment.
                Write-Verbose "Pipeline 0 : $($ast.left.extent.text)"
                $pipelineElements = $ast.right.PipelineElements
                [PSCustomObject]@{
                    Pipeline = 0
                    Command  = $ast.left.extent.text
                    Resolved = $ast.operator
                    params   = $ast.right.extent.text
                }
            }
            else {
                $pipelineElements = $ast.PipelineElements
            }
            foreach ($pipeline in $pipelineElements) {
                if ($pipeline.commandElements) {
                    $piped = $pipeline.CommandElements[0].Value
                    Write-Verbose "Pipeline $i : $piped"
                    $command = $ExecutionContext.InvokeCommand.GetCommand($piped, 'All')
                    if (-Not $command) {
                        # the color is perhaps not best practice, but it is visually distinct.
                        # $resolved = 'CommandNotFound'
                        $resolved = "$([char]27)[101mCommandNotFound$([char]27)[0m"
                    }
                    elseif ($command.ResolvedCommand) {
                        Write-Verbose "Resolved alias to $($command.ResolvedCommand.Name)"
                        $resolved = $command.ResolvedCommand
                    }
                    else {
                        $resolved = $command
                    }
                    $param = $pipeline.CommandElements.extent.text -join ' '
                }
                else {
                    # when the pipeline is started by a variable.
                    Write-Verbose "Pipeline $i : $pipeline"
                    $piped = $resolved = $pipeline
                    $param = $pipeline.expression.extent.text
                }
                [PSCustomObject]@{
                    Pipeline = $i
                    Command  = $piped
                    Resolved = $resolved
                    params   = $param.replace($piped,'').Trim()
                }
                $i++
            }
        }
    }
}