feat: Porting XML Template to Language Function (Fixes #632)

Author: James Brundage

Commands/Languages/XML/XML-Language.ps.ps1

@@ -0,0 +1,42 @@
+Language function XML {
+<#
+.SYNOPSIS
+    XML Template Transpiler.
+.DESCRIPTION
+    Allows PipeScript to generate XML.
+
+    Multiline comments blocks like this ```<!--{}-->``` will be treated as blocks of PipeScript.
+#>
+[ValidatePattern('\.xml$')]
+param()
+
+    # We start off by declaring a number of regular expressions:
+    $startComment = '<\!--' # * Start Comments ```<!--```
+    $endComment   = '-->'   # * End Comments   ```-->```
+    $Whitespace   = '[\s\n\r]{0,}'
+    # * StartPattern     ```$StartComment + '{' + $Whitespace```
+    $startPattern = "(?<PSStart>${startComment}\{$Whitespace)"
+    # * EndPattern       ```$whitespace + '}' + $EndComment```
+    $endPattern   = "(?<PSEnd>$Whitespace\}${endComment}\s{0,})"
+    
+    $ForeachObject = {
+        $in = $_
+        if (($in -is [string]) -or 
+            ($in.GetType -and $in.GetType().IsPrimitive)) {
+            $in
+        } elseif ($in.ChildNodes) {
+            foreach ($inChildNode in $in.ChildNodes) {
+                if ($inChildNode.NodeType -ne 'XmlDeclaration') {
+                    $inChildNode.OuterXml
+                }
+            }
+        } else {
+            $inXml = (ConvertTo-Xml -Depth 100 -InputObject $in)
+            foreach ($inChildNode in $inXml.ChildNodes) {
+                if ($inChildNode.NodeType -ne 'XmlDeclaration') {
+                    $inChildNode.OuterXml
+                }
+            }
+        }
+    }
+}