Using PowerShell’s PsParser::Tokenize, Discover Functions in PowerShell Scripts

Another CTP drop for PowerShell is expected in December. One of the new features, Modules, allows PowerShell code to be organized in self-contained, reusable units.

In anticipation of this feature, I am experimenting with building PowerShell solutions by organizing several related functions into a single script that is sourced. Think; Clear-Item, Copy-Item, Get-Item, Invoke-Item,  but tailored to a custom system.

The Challenge

As the PowerShell code grows, remembering the functions is harder. Here is script that discovers them.

Get-Functions

Get-Functions takes a single file, a list of files or the –Recurse switch. The recurse switch finds all the functions in all the files in the subdirectories.

param(

 $files,

 [switch] $recurse

)

$parser = [System.Management.Automation.PsParser]

if($recurse) {

 $files=(dir . -Recurse *.ps1)

} else {

 if(!$files) {throw "Please enter a file for scanning."}

 if($files -is [String]) {$files=(dir $files)}

}

ForEach($file in $files) {

 $parser::Tokenize((Get-Content $file.FullName), [ref] $null) |

 ForEach {

  $PSToken = $_

  if($PSToken.Type -eq  'Keyword' -and

     $PSToken.Content -eq 'Function' ) {     

     $functionKeyWordFound = $true

  }

  if($functionKeyWordFound -and

     $PSToken.Type -eq  'CommandArgument') {

     '' | Select `

      @{

       Name="FunctionName"

       Expression={$PSToken.Content}

      },

      @{

       Name="Line"

       Expression={$PSToken.StartLine}

      },

      @{

       Name="File"

       Expression={$file.FullName}

      }

      $functionKeyWordFound = $false

  }

 }

}

Example

I downloaded PowerShell code for two books, Windows PowerShell in Action and Windows PowerShell Cookbook. Then ran the command:

Get-Functions -r | Out-GridView

The Out-GridView lets you sort columns and filter. Typing in the search box scans each column, showing matches.

Get-Functions provides the file name and line number where to find function.

Thanks to James Brundage. He blogged the approach in WPF & PowerShell – Part 2 (Exploring WPF (and the rest of .NET) with Scripts). Also, he pointed out timings comparing PSObject creation using Add-Member v. the above Select @{name;expression} approach. Super helpful.

Download Get-Functions