doing textwrap and dedent in Windows Powershell (or dotNet aka .net)

Question

Background

Python has "textwrap" and "dedent" functions. They do pretty much what you expect to any string you supply.

textwrap.wrap(text[, width[, ...]])

Wraps the single paragraph in text (a string) so every line is at most width characters long. Returns a list of output lines, without final newlines.

textwrap.dedent(text)

Remove any common leading whitespace from every line in text.

http://docs.python.org/library/textwrap.html

Question:

How do you do this in Windows PowerShell, (or with .NET methods you call from PowerShell)?

Answer 1

I think you should create a CLI utility with this behaviour and customize it as you like. And then just use it as a command in your shell. Maybe you will also need to add you script into PATH.

Answer 2

This is a negligent code...

#requires -version 2.0
    function wrap( [string]$text, [int]$width ) {
    $i=0;
    $text.ToCharArray() | group { [Math]::Floor($i/$width); (gv i).Value++ } | % { -join $_.Group }
}

function dedent( [string[]]$text ) {
    $i = $text | % { $_ -match "^(\s*)" | Out-Null ; $Matches[1].Length } | sort | select -First 1
    $text -replace "^\s{$i}"
}

Answer 3

Looking at the results in python at http://try-python.mired.org/, it appears that the correct algorithm splits at word boundaries, rather than taking fixed-length substrings from the text.

function wrap( [string]$text, [int]$width = 70 ) {
  $line = ''

  # Split the text into words.
  $text.Split( ' '.ToCharArray( ) ) | % {
    # Initialize the first line with the first word.
    if( -not $line ) { $line = $_ }
    else {
      # For each new word, try to add it to the current line.
      $next = $line + ' ' + $_

      # If the new word goes over the limit,
      #  return the last line and start a new one.
      if( $next.Length -ge $width ) { $line; $line = $_ }
      # Otherwise, use the updated line with the new word.
      else { $line = $next }
    }
  }

  # Return the last line, containing the remainder of the text.
  $line
}

And here's an alternate implementation for dedent as well.

function dedent( [string[]]$lines ) {
  # Find the shortest length of leading whitespace common to all lines.
  $commonLength = (
    $lines | % {
      $i = 0
      while( $i -lt $_.Length -and [char]::IsWhitespace( $_, $i ) ) { ++$i }
      $i
    } | Measure-Object -minimum
  ).Minimum

  # Remove the common whitespace from each string
  $lines | % { $_.Substring( $commonLength ) }
}

Hopefully their greater verbosity will provide better clarity :)