fixes indexing on using: statements

Module/PSParallelPipeline.psd1

@@ -11,7 +11,7 @@
     RootModule        = 'PSParallelPipeline.psm1'
 
     # Version number of this module.
-    ModuleVersion     = '1.1.3'
+    ModuleVersion     = '1.1.4'
 
     # Supported PSEditions
     # CompatiblePSEditions = @()

Module/private/InvocationManager.ps1

@@ -2,6 +2,8 @@
 using namespace System.Diagnostics
 using namespace System.Management.Automation
 using namespace System.Management.Automation.Host
+using namespace System.Management.Automation.Language
+using namespace System.Text
 using namespace System.Threading
 
 class InvocationManager : IDisposable {
@@ -107,4 +109,42 @@ class InvocationManager : IDisposable {
             $runspace.Dispose()
         }
     }
+
+    static [hashtable] GetUsingStatements([scriptblock] $scriptblock, [PSCmdlet] $cmdlet) {
+        $usingParams = @{}
+        foreach ($usingstatement in $scriptblock.Ast.FindAll({ $args[0] -is [UsingExpressionAst] }, $true)) {
+            $variableAst = [UsingExpressionAst]::ExtractUsingVariable($usingstatement)
+            $varPath = $variableAst.VariablePath.UserPath
+            $varText = $usingstatement.ToString()
+
+            if ($usingstatement.SubExpression -is [VariableExpressionAst]) {
+                $varText = $varText.ToLowerInvariant()
+            }
+
+            $key = [Convert]::ToBase64String([Encoding]::Unicode.GetBytes($varText))
+
+            if ($usingParams.ContainsKey($key)) {
+                continue
+            }
+
+            $value = $cmdlet.SessionState.PSVariable.GetValue($varPath)
+
+            if ($value -is [scriptblock]) {
+                $cmdlet.ThrowTerminatingError([ErrorRecord]::new(
+                    [PSArgumentException]::new('Passed-in script block variables are not supported.'),
+                    'VariableCannotBeScriptBlock',
+                    [ErrorCategory]::InvalidType,
+                    $value))
+            }
+
+            if ($usingstatement.SubExpression -is [IndexExpressionAst]) {
+                $idx = $usingstatement.SubExpression.Index.SafeGetValue()
+                $value = $value[$idx]
+            }
+
+            $usingParams.Add($key, $value)
+        }
+
+        return $usingParams
+    }
 }

Module/public/Invoke-Parallel.ps1

@@ -36,6 +36,10 @@ function Invoke-Parallel {
     )
 
     begin {
+        $usingParams = [InvocationManager]::GetUsingStatements(
+            $ScriptBlock,
+            $PSCmdlet)
+
         try {
             $iss = [initialsessionstate]::CreateDefault2()
 
@@ -60,30 +64,6 @@ function Invoke-Parallel {
                     [SessionStateFunctionEntry]::new($function, $def.Definition))
             }
 
-            $usingParams = @{}
-
-            # Thanks to mklement0 for catching up a bug here.
-            # https://github.com/mklement0
-            foreach ($usingstatement in $ScriptBlock.Ast.FindAll({ $args[0] -is [UsingExpressionAst] }, $true)) {
-                $varText = $usingstatement.Extent.Text
-                $varPath = $usingstatement.SubExpression.VariablePath.UserPath
-
-                $key = [Convert]::ToBase64String([Encoding]::Unicode.GetBytes($varText.ToLowerInvariant()))
-                if (-not $usingParams.ContainsKey($key)) {
-                    $value = $PSCmdlet.SessionState.PSVariable.GetValue($varPath)
-
-                    if ($value -is [scriptblock]) {
-                        $PSCmdlet.ThrowTerminatingError([ErrorRecord]::new(
-                            [PSArgumentException]::new('Passed-in script block variables are not supported.'),
-                            'VariableCannotBeScriptBlock',
-                            [ErrorCategory]::InvalidType,
-                            $value))
-                    }
-
-                    $usingParams.Add($key, $value)
-                }
-            }
-
             $im = [InvocationManager]::new($ThrottleLimit, $Host, $iss, $UseNewRunspace.IsPresent)
 
             if ($withTimeout = $PSBoundParameters.ContainsKey('TimeoutSeconds')) {

tests/PSParallelPipeline.tests.ps1

@@ -134,5 +134,11 @@
                 1..1 | Invoke-Parallel { $sb } -Variables @{ sb = $sb }
             } | Should -Throw
         }
+
+        It 'Allows indexing on using: statements' {
+            $arr = 0..10; $hash = @{ foo = 'bar' }
+            1 | Invoke-Parallel { $using:arr[-1] } | Should -BeExactly 10
+            1 | Invoke-Parallel { $using:hash['FOO'] } | Should -BeExactly 'bar'
+        }
     }
 }