8.7 Program: Show Colorized Script Content

Example 8-3. Show-ColorizedContent.ps1

##############################################################################
##
## Show-ColorizedContent
##
## From PowerShell Cookbook (O'Reilly)
## by Lee Holmes (http://www.leeholmes.com/guide)
##
##############################################################################

<#

.SYNOPSIS

Displays syntax highlighting, line numbering, and range highlighting for
PowerShell scripts.

.EXAMPLE

PS > Show-ColorizedContent Invoke-MyScript.ps1

001 | function Write-Greeting
002 | {
003 |     param($greeting)
004 |     Write-Host "$greeting World"
005 | }
006 |
007 | Write-Greeting "Hello"

.EXAMPLE

PS > Show-ColorizedContent Invoke-MyScript.ps1 -highlightRange (1..3+7)

001 > function Write-Greeting
002 > {
003 >     param($greeting)
004 |     Write-Host "$greeting World"
005 | }
006 |
007 > Write-Greeting "Hello"

#>

param(
    ## The path to colorize
    [Parameter(Mandatory = $true)]
    $Path,

    ## The range of lines to highlight
    $HighlightRange = @(),

    ## Switch to exclude line numbers
    [Switch] $ExcludeLineNumbers
)

Set-StrictMode -Version 3

## Colors to use for the different script tokens.
## To pick your own colors:
## [Enum]::GetValues($host.UI.RawUI.ForegroundColor.GetType()) |
##     Foreach-Object { Write-Host -Fore $_ "$_" }
$replacementColors = @{
    'Attribute' = 'DarkCyan'
    'Command' = 'Blue'
    'CommandArgument' = 'Magenta'
    'CommandParameter' = 'DarkBlue'
    'Comment' = 'DarkGreen'
    'GroupEnd' = 'Black'
    'GroupStart' = 'Black'
    'Keyword' = 'DarkBlue'
    'LineContinuation' = 'Black'
    'LoopLabel' = 'DarkBlue'
    'Member' = 'Black'
    'NewLine' = 'Black'
    'Number' = 'Magenta'
    'Operator' = 'DarkGray'
    'Position' = 'Black'
    'StatementSeparator' = 'Black'
    'String' = 'DarkRed'
    'Type' = 'DarkCyan'
    'Unknown' = 'Black'
    'Variable' = 'Red'
}

$highlightColor = "Red"
$highlightCharacter = ">"
$highlightWidth = 6
if($excludeLineNumbers) { $highlightWidth = 0 }

## Read the text of the file, and tokenize it
$content = Get-Content $Path -Raw
$parsed = [System.Management.Automation.PsParser]::Tokenize(
    $content, [ref] $null) | Sort StartLine,StartColumn

## Write a formatted line -- in the format of:
## <Line Number> <Separator Character> <Text>
function WriteFormattedLine($formatString, [int] $line)
{
    if($excludeLineNumbers) { return }

    ## By default, write the line number in gray, and use
    ## a simple pipe as the separator
    $hColor = "DarkGray"
    $separator = "|"

    ## If we need to highlight the line, use the highlight
    ## color and highlight separator as the separator
    if($highlightRange -contains $line)
    {
        $hColor = $highlightColor
        $separator = $highlightCharacter
    }

    ## Write the formatted line
    $text = $formatString -f $line,$separator
    Write-Host -NoNewLine -Fore $hColor -Back White $text
}

## Complete the current line with filler cells
function CompleteLine($column)
{
    ## Figure how much space is remaining
    $lineRemaining = $host.UI.RawUI.WindowSize.Width -
        $column - $highlightWidth + 1

    ## If we have less than 0 remaining, we've wrapped onto the
    ## next line. Add another buffer width worth of filler
    if($lineRemaining -lt 0)
    {
        $lineRemaining += $host.UI.RawUI.WindowSize.Width
    }

    Write-Host -NoNewLine -Back White (" " * $lineRemaining)
}


## Write the first line of context information (line number,
## highlight character.)
Write-Host
WriteFormattedLine "{0:D3} {1} " 1

## Now, go through each of the tokens in the input
## script
$column = 1
foreach($token in $parsed)
{
    $color = "Gray"

    ## Determine the highlighting color for that token by looking
    ## in the hashtable that maps token types to their color
    $color = $replacementColors[[string]$token.Type]
    if(-not $color) { $color = "Gray" }

    ## If it's a newline token, write the next line of context
    ## information
    if(($token.Type -eq "NewLine") -or ($token.Type -eq "LineContinuation"))
    {
        CompleteLine $column
        WriteFormattedLine "{0:D3} {1} " ($token.StartLine + 1)
        $column = 1
    }
    else
    {
        ## Do any indenting
        if($column -lt $token.StartColumn)
        {
            $text = " " * ($token.StartColumn - $column)
            Write-Host -Back White -NoNewLine $text
            $column = $token.StartColumn
        }

        ## See where the token ends
        $tokenEnd = $token.Start + $token.Length - 1

        ## Handle the line numbering for multi-line strings and comments
        if(
            (($token.Type -eq "String") -or
            ($token.Type -eq "Comment")) -and
            ($token.EndLine -gt $token.StartLine))
        {
            ## Store which line we've started at
            $lineCounter = $token.StartLine

            ## Split the content of this token into its lines
            ## We use the start and end of the tokens to determine
            ## the position of the content, but use the content
            ## itself (rather than the token values) for manipulation.
            $stringLines = $(
                -join $content[$token.Start..$tokenEnd] -split "`n")

            ## Go through each of the lines in the content
            foreach($stringLine in $stringLines)
            {
                $stringLine = $stringLine.Trim()

                ## If we're on a new line, fill the right hand
                ## side of the line with spaces, and write the header
                ## for the new line.
                if($lineCounter -gt $token.StartLine)
                {
                    CompleteLine $column
                    WriteFormattedLine "{0:D3} {1} " $lineCounter
                    $column = 1
                }

                ## Now write the text of the current line
                Write-Host -NoNewLine -Fore $color -Back White $stringLine
                $column += $stringLine.Length
                $lineCounter++
            }
        }
        ## Write out a regular token
        else
        {
            ## We use the start and end of the tokens to determine
            ## the position of the content, but use the content
            ## itself (rather than the token values) for manipulation.
            $text = (-join $content[$token.Start..$tokenEnd])
            Write-Host -NoNewLine -Fore $color -Back White $text
        }

        ## Update our position in the column
        $column = $token.EndColumn
    }
}

CompleteLine $column
Write-Host