Adding ValidateScriptBlock (#93)

Author: James Brundage

Transpilers/Parameters/ValidateScriptBlock.psx.ps1

@@ -0,0 +1,132 @@
+<#
+.SYNOPSIS
+    Validates Script Blocks
+.DESCRIPTION
+    Validates Script Blocks for a number of common scenarios.
+.EXAMPLE
+    {
+        param(
+        [ValidateScriptBlock(Safe)]
+        [ScriptBlock]
+        $ScriptBlock
+        )
+
+        $ScriptBlock
+    } | .>PipeScript
+.EXAMPLE
+    {
+        param(
+        [ValidateScriptBlock(NoBlock,NoParameters)]
+        [ScriptBlock]
+        $ScriptBlock
+        )
+
+        $ScriptBlock
+    } | .>PipeScript
+.EXAMPLE
+    {
+        param(
+        [ValidateScriptBlock(OnlyParameters)]
+        [ScriptBlock]
+        $ScriptBlock
+        )
+
+        $ScriptBlock
+    } | .>PipeScript
+#>
+[CmdletBinding(DefaultParameterSetName='Parameter')]
+param(
+# If set, will validate that ScriptBlock is "safe".
+# This will attempt to recreate the Script Block as a datalanguage block and execute it.
+[Alias('Safe')]
+[switch]
+$DataLanguage,
+
+# If set, will ensure that the [ScriptBlock] only has parameters
+[Alias('OnlyParameters')]
+[switch]
+$ParameterOnly,
+
+# If set, will ensure that the [ScriptBlock] has no named blocks.
+[Alias('NoBlocks')]
+[switch]
+$NoBlock,
+
+# If set, will ensure that the [ScriptBlock] has no parameters.
+[Alias('NoParameters','NoParam')]
+[switch]
+$NoParameter,
+
+# A VariableExpression.  If provided, the Validation attributes will apply to this variable.
+[Parameter(Mandatory,ValueFromPipeline,ParameterSetName='VariableExpressionAST')]
+[Management.Automation.Language.VariableExpressionAST]
+$VariableAST
+)
+
+process {
+
+$validateScripts = @(
+    if ($DataLanguage) {
+@'
+[ValidateScript({
+    $sbCopy = "data { $_ }"
+    try {
+        $dataOutput = & ([ScriptBlock]::Create($sbCopy))
+        return $true
+    } catch {
+        throw    
+    }
+})]
+'@
+    }
+    if ($ParameterOnly) {
+@'
+[ValidateScript({
+    $statementCount = 0
+    $statementCount += $_.Ast.DynamicParamBlock.Statements.Count
+    $statementCount += $_.Ast.BeginBlock.Statements.Count
+    $statementCount += $_.Ast.ProcessBlock.Statements.Count
+    $statementCount += $_.Ast.EndBlock.Statements.Count
+    if ($statementCount) {
+        throw "ScriptBlock should have no statements"
+    } else { 
+        return $true
+    }
+})]
+'@
+    }
+    if ($NoBlock) {
+@'
+[ValidateScript({
+    if ($_.Ast.DynamicParamBlock -or $_.Ast.BeginBlock -or $_.Ast.ProcessBlock) {
+        throw "ScriptBlock should not have any named blocks"
+    }
+    return $true    
+})]
+'@        
+    }
+    if ($NoParameter) {
+@'
+[ValidateScript({
+    if ($_.Ast.ParamBlock.Parameters.Count) {
+        throw "ScriptBlock should not have parameters"
+    }
+    return $true    
+})]
+'@
+    }    
+)
+    if (-not $validateScripts) { return }
+
+    [scriptblock]::Create(@"
+$($validateScripts -join [Environment]::NewLine)$(
+    if ($psCmdlet.ParameterSetName -eq 'Parameter') {
+        'param()'
+    } else {
+        '$' + $VariableAST.variablePath.ToString()
+    }
+)
+"@.Trim())
+
+
+}