Adding ValidatePropertyName Transpiler (#59)

Author: James Brundage

Transpilers/Parameters/ValidatePropertyName.psx.ps1

@@ -0,0 +1,94 @@
+<#
+.SYNOPSIS
+    Validates Property Names
+.DESCRIPTION
+    Validates that an object has one or more property names.
+.Example
+    {
+        param(
+        [ValidatePropertyName(PropertyName='a','b')]
+        $InputObject
+        )
+    } | .>PipeScript
+.EXAMPLE
+    [PSCustomObject]@{a='a';b='b'} |
+        .> {
+            param(
+            [ValidatePropertyName(PropertyName='a','b')]
+            [vfp]
+            $InputObject
+            )
+
+            $InputObject
+        }
+.EXAMPLE
+    @{a='a'} |
+        .> {
+            param(
+            [ValidatePropertyName(PropertyName='a','b')]
+            [vfp]
+            $InputObject
+            )
+
+            $InputObject
+        }
+#>
+[CmdletBinding(DefaultParameterSetName='Parameter')]
+[Alias('ValidatePropertyNames')]
+param(
+# The property names being validated.
+[Parameter(Mandatory,Position=0)]
+[string[]]
+$PropertyName,
+
+# A variable expression.
+# If this is provided, will apply a ```[ValidateScript({})]``` attribute to the variable, constraining future values.
+[Parameter(ValueFromPipeline,ParameterSetName='VariableExpressionAST')]
+[Management.Automation.Language.VariableExpressionAST]
+$VariableAST
+)
+
+process {
+    $checkPropertyNames = 
+{        
+    $foundProperties = @(
+        foreach ($propName in $PropertyNames) {
+            if ($inObject -is [Collections.IDictionary]) {
+                $inObject.Contains($propName)
+            } elseif ($inObject.psobject) {
+                $null -ne $inObject.psobject.properties[$propName]
+            } else {
+                $false
+            }
+        }
+    )
+    $missingProperties = 
+        @(
+            for ($propertyIndex = 0; $propertyIndex -lt $propertyNames.Length; $propertyIndex++) {
+            if (-not $foundProperties[$propertyIndex]) {
+                $PropertyNames[$propertyIndex]
+            }
+        })
+}
+
+    
+[ScriptBlock]::Create(@"
+[ValidateScript({
+    `$propertyNames = '$($PropertyName -join "','")'
+    `$inObject = `$_
+$checkPropertyNames
+    if (`$MissingProperties) {
+        throw "Missing Properties: `$(`$missingProperties -join ',')"
+    }
+    return `$true
+})]
+$(
+    if ($psCmdlet.ParameterSetName -eq 'Parameter') {
+        'param()'
+    } else {
+        '$' + $VariableAST.variablePath.ToString()
+    }
+)
+"@)
+
+}