Adding TypeExpression Transpiler (#6)

Author: James Brundage

Transpilers/Core/PipeScript.TypeExpression.psx.ps1

@@ -0,0 +1,95 @@
+<#
+.SYNOPSIS
+    The PipeScript TypeExpression Transpiler 
+.DESCRIPTION
+    Type Expressions may be transpiled.
+    
+.Example
+    {
+        [include[a.ps1]]
+    } | .>PipeScript
+#>
+param(
+# The attributed expression
+[Parameter(Mandatory,ParameterSetName='AttributedExpressionAst',ValueFromPipeline)]
+[Management.Automation.Language.TypeExpressionAst]
+$TypeExpressionAst
+)
+
+begin {
+    if (-not $script:TypeAcceleratorsList) {
+        $script:TypeAcceleratorsList = [PSObject].Assembly.GetType("System.Management.Automation.TypeAccelerators")::Get.Keys
+    }
+    function TypeConstraintToArguments {
+        param (
+            [Parameter(ValueFromPipeline)]
+            $TypeName
+        )
+        begin {
+            $TypeNameArgs = @()
+            $TypeNameParams = @{}
+        }
+        process {
+
+            if ($TypeName.IsGeneric) {
+                $TypeNameParams[$typeName.Name] = 
+                    $typeName.GenericArguments |
+                        UnpackTypeConstraintArgs
+            } elseif (-not $TypeName.IsArray) {
+                $TypeNameArgs += $TypeName.Name
+            }
+        }
+        end {
+            [PSCustomObject]@{
+                ArgumentList = $TypeNameArgs
+                Parameter    = $TypeNameParams
+            }                        
+        }
+    }
+}
+
+process {
+    $IsRealType = $TypeExpressionAst.TypeName.GetReflectionType()
+    if ($IsRealType) { return }
+
+    $transpilerStepName  = 
+        if ($TypeExpressionAst.TypeName.TypeName) {
+            $TypeExpressionAst.TypeName.TypeName.Name
+        } else {
+            $TypeExpressionAst.TypeName.Name
+        }
+
+    if ($transpilerStepName -eq 'ordered') { return }
+
+    $foundTranspiler =
+        if ($currentInput -isnot [string]) {
+            Get-Transpiler -CouldPipe $currentInput -TranspilerName "$transpilerStepName"
+        } else {
+            Get-Transpiler -TranspilerName "$transpilerStepName"
+        }
+
+    $argList = @()
+    $parameters = @{}
+
+    if ($TypeExpressionAst.TypeName.IsGeneric) {
+        $TypeExpressionAst.TypeName.GenericArguments | 
+        TypeConstraintToArguments | 
+            ForEach-Object {
+                if ($_.ArgumentList) {
+                    $arglist += $_.ArgumentList
+                }
+                if ($_.Parameter.Count) {
+                    $parameters += $_.Parameter
+                }
+            }
+    }
+    
+        
+    if ($foundTranspiler -and $currentInput -isnot [string]) {
+        Invoke-PipeScript -CommandInfo $foundTranspiler  -ArgumentList $arglist -Parameter $parameters                                          
+    } elseif ($foundTranspiler -and $currentInput -is [string]) {
+        Invoke-PipeScript -CommandInfo $foundTranspiler -ArgumentList $arglist -Parameter $parameters
+    } elseif ($script:TypeAcceleratorsList -notcontains $transpilerStepName -and $transpilerStepName -notin 'Ordered') {
+        Write-Error "Unable to find a transpiler for [$TranspilerStepName]"
+    }    
+}