PipeScript

0.1.1

Transpilers/Syntax/PipedAssignment.psx.ps1

<#
.SYNOPSIS
    Piped Assignment Transpiler
.DESCRIPTION
    Enables Piped Assignment (```|=|```).

    Piped Assignment allows for an expression to be reassigned based off of the pipeline input.
.EXAMPLE
    {
        $Collection |=| Where-Object Name -match $Pattern
    } | .>PipeScript

    # This will become:

    $Collection = $Collection | Where-Object Name -match $pattern
.EXAMPLE
    {
        $Collection |=| Where-Object Name -match $pattern | Select-Object -ExpandProperty Name
    } | .>PipeScript

    # This will become

    $Collection = $Collection |
            Where-Object Name -match $pattern |
            Select-Object -ExpandProperty Name
#>
[ValidateScript({
    $ast = $_
    if ($ast.PipelineElements.Count -ge 3 -and
    $ast.PipelineElements[1].CommandElements -and 
    $ast.PipelineElements[1].CommandElements[0].Value -eq '=') {
        return $true
    }
    return $false
})]
param(    
[Parameter(Mandatory,ValueFromPipeline)]
[Management.Automation.Language.PipelineAst]
$PipelineAst
)

process {
    $null = $PipelineAst.PipelineElements[0]
    [ScriptBlock]::Create(@"
$($PipelineAst.PipelineElements[0]) = $($PipelineAst.PipelineElements[0]) | $(
    $(
        $(if ($PipelineAst.PipelineElements.Count -gt 3) {
            [Environment]::NewLine + (' ' * 4)
        } else {
            ''
        }) +
        (@($PipelineAst.PipelineElements[2..$PipelineAst.PipelineElements.Count]) -join (
            ' |' + [Environment]::NewLine + (' ' * 4)
        ))
    )
)
"@)
}