Adding Kusto Template Support (Fixes #416)

Author: James Brundage

Transpilers/Templates/Kusto.Template.psx.ps1

@@ -0,0 +1,86 @@
+<#
+.SYNOPSIS
+    Kusto Template Transpiler.
+.DESCRIPTION
+    Allows PipeScript to generate Kusto files.
+
+    Multiline comments with /*{}*/ will be treated as blocks of PipeScript.
+
+    Multiline comments can be preceeded or followed by 'empty' syntax, which will be ignored.
+
+    The Kusto Template Transpiler will consider the following syntax to be empty:
+
+    * ```null```
+    * ```""```
+    * ```''```
+#>
+[ValidatePattern('\.kql$')]
+param(
+# The command information.  This will include the path to the file.
+[Parameter(Mandatory,ValueFromPipeline,ParameterSetName='TemplateFile')]
+[Management.Automation.CommandInfo]
+$CommandInfo,
+
+# If set, will return the information required to dynamically apply this template to any text.
+[Parameter(Mandatory,ParameterSetName='TemplateObject')]
+[switch]
+$AsTemplateObject,
+
+# A dictionary of parameters.
+[Collections.IDictionary]
+$Parameter,
+
+# A list of arguments.
+[PSObject[]]
+$ArgumentList
+)
+
+begin {
+    # We start off by declaring a number of regular expressions:
+    $startComment = '/\*' # * Start Comments ```\*```
+    $endComment   = '\*/' # * End Comments   ```/*```
+    $Whitespace   = '[\s\n\r]{0,}'
+    # * IgnoredContext ```String.empty```, ```null```, blank strings and characters
+    $IgnoredContext = "(?<ignore>(?>$("null", '""', "''" -join '|'))\s{0,}){0,1}"
+    # * StartRegex     ```$IgnoredContext + $StartComment + '{' + $Whitespace```
+    $startRegex = "(?<PSStart>${IgnoredContext}${startComment}\{$Whitespace)"
+    # * EndRegex       ```$whitespace + '}' + $EndComment + $ignoredContext```
+    $endRegex   = "(?<PSEnd>$Whitespace\}${endComment}\s{0,}${IgnoredContext})"
+
+    # Create a splat containing arguments to the core inline transpiler
+    $Splat      = [Ordered]@{
+        StartPattern  = $startRegex
+        EndPattern    = $endRegex
+    }
+}
+
+process {
+    # If we have been passed a command
+    if ($CommandInfo) {
+        # add parameters related to the file.
+        $Splat.SourceFile = $commandInfo.Source -as [IO.FileInfo]
+        $Splat.SourceText = [IO.File]::ReadAllText($commandInfo.Source)
+    }
+    
+    if ($Parameter) { $splat.Parameter = $Parameter }
+    if ($ArgumentList) { $splat.ArgumentList = $ArgumentList }
+
+    $splat.ForeachObject = {
+        $in = $_
+        if (($in -is [string]) -or 
+            ($in.GetType -and $in.GetType().IsPrimitive)) {
+            $in
+        } else {
+            "dynamic($(ConvertTo-Json -Depth 100 -InputObject $in))"
+        }
+    }
+
+    # If we are being used within a keyword,
+    if ($AsTemplateObject) {
+        $splat # output the parameters we would use to evaluate this file.
+    } else {
+        # Otherwise, call the core template transpiler
+        .>PipeScript.Template @Splat # and output the changed file.
+    }
+}
+