From 12afd9c3dded662a91073477abb8c5835aca3f98 Mon Sep 17 00:00:00 2001
From: David Wilson <daviwil@microsoft.com>
Date: Mon, 20 Mar 2017 11:53:43 -0700
Subject: [PATCH] Add initial support for feature flags

This change adds initial support for feature flags in the
EditorServicesHost so that we can enable new experimental features
conditionally while maintaining current behavior for most users.
---
 .../PowerShellEditorServices/PowerShellEditorServices.psm1 | 7 ++++++-
 src/PowerShellEditorServices.Host/EditorServicesHost.cs    | 6 +++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/module/PowerShellEditorServices/PowerShellEditorServices.psm1 b/module/PowerShellEditorServices/PowerShellEditorServices.psm1
index 84ee85940..c2ee6cec7 100644
--- a/module/PowerShellEditorServices/PowerShellEditorServices.psm1
+++ b/module/PowerShellEditorServices/PowerShellEditorServices.psm1
@@ -52,6 +52,10 @@ function Start-EditorServicesHost {
         [string]
         $DebugServiceOnly,
 
+        [string[]]
+        [ValidateNotNull()]
+        $FeatureFlags = @(),
+
         [switch]
         $WaitForDebugger
     )
@@ -65,7 +69,8 @@ function Start-EditorServicesHost {
                 $hostDetails,
                 $BundledModulesPath,
                 $EnableConsoleRepl.IsPresent,
-                $WaitForDebugger.IsPresent)
+                $WaitForDebugger.IsPresent,
+                $FeatureFlags)
 
         # Build the profile paths using the root paths of the current $profile variable
         $profilePaths = New-Object Microsoft.PowerShell.EditorServices.Session.ProfilePaths @(
diff --git a/src/PowerShellEditorServices.Host/EditorServicesHost.cs b/src/PowerShellEditorServices.Host/EditorServicesHost.cs
index 363eba04c..43ec42565 100644
--- a/src/PowerShellEditorServices.Host/EditorServicesHost.cs
+++ b/src/PowerShellEditorServices.Host/EditorServicesHost.cs
@@ -8,6 +8,7 @@
 using Microsoft.PowerShell.EditorServices.Session;
 using Microsoft.PowerShell.EditorServices.Utility;
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Reflection;
 using System.Threading;
@@ -33,6 +34,7 @@ public class EditorServicesHost
         private HostDetails hostDetails;
         private string bundledModulesPath;
         private DebugAdapter debugAdapter;
+        private HashSet<string> featureFlags;
         private LanguageServer languageServer;
 
         #endregion
@@ -60,13 +62,15 @@ public EditorServicesHost(
             HostDetails hostDetails,
             string bundledModulesPath,
             bool enableConsoleRepl,
-            bool waitForDebugger)
+            bool waitForDebugger,
+            string[] featureFlags)
         {
             Validate.IsNotNull(nameof(hostDetails), hostDetails);
 
             this.hostDetails = hostDetails;
             this.enableConsoleRepl = enableConsoleRepl;
             this.bundledModulesPath = bundledModulesPath;
+            this.featureFlags = new HashSet<string>(featureFlags ?? new string[0]);
 
 #if DEBUG
             int waitsRemaining = 10;