Adding Piped Assignment Transpiler (#88)

Author: James Brundage

Transpilers/Syntax/PipedAssignment.psx.ps1

@@ -0,0 +1,52 @@
+<#
+.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 | Foreach-Object { $_.Name }
+    } | .>PipeScript
+#>
+[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)
+        ))
+    )
+)
+"@)
+}