Implemented -LanguageServiceOnly switch.

Author: dkattan

module/PowerShellEditorServices/Start-EditorServices.ps1

@@ -25,19 +25,19 @@
     at the PowerShell Editor Services GitHub repository:
     https://github.com/PowerShell/PowerShellEditorServices/blob/master/module/PowerShellEditorServices/Start-EditorServices.ps1'
 #>
-[CmdletBinding(DefaultParameterSetName="NamedPipe")]
+[CmdletBinding(DefaultParameterSetName = "NamedPipe")]
 param(
-    [Parameter(Mandatory=$true)]
+    [Parameter(Mandatory = $true)]
     [ValidateNotNullOrEmpty()]
     [string]
     $HostName,
 
-    [Parameter(Mandatory=$true)]
+    [Parameter(Mandatory = $true)]
     [ValidateNotNullOrEmpty()]
     [string]
     $HostProfileId,
 
-    [Parameter(Mandatory=$true)]
+    [Parameter(Mandatory = $true)]
     [ValidateNotNullOrEmpty()]
     [string]
     $HostVersion,
@@ -52,10 +52,10 @@ param(
     [ValidateSet("Diagnostic", "Verbose", "Normal", "Warning", "Error")]
     $LogLevel,
 
-	[Parameter(Mandatory=$true)]
-	[ValidateNotNullOrEmpty()]
-	[string]
-	$SessionDetailsPath,
+    [Parameter(Mandatory = $true)]
+    [ValidateNotNullOrEmpty()]
+    [string]
+    $SessionDetailsPath,
 
     [switch]
     $EnableConsoleRepl,
@@ -66,6 +66,9 @@ param(
     [switch]
     $DebugServiceOnly,
 
+    [switch]
+    $LanguageServiceOnly,
+
     [string[]]
     $AdditionalModules,
 
@@ -78,35 +81,35 @@ param(
     [switch]
     $ConfirmInstall,
 
-    [Parameter(ParameterSetName="Stdio", Mandatory=$true)]
+    [Parameter(ParameterSetName = "Stdio", Mandatory = $true)]
     [switch]
     $Stdio,
 
-    [Parameter(ParameterSetName="NamedPipe")]
+    [Parameter(ParameterSetName = "NamedPipe")]
     [string]
     $LanguageServicePipeName = $null,
 
-    [Parameter(ParameterSetName="NamedPipe")]
+    [Parameter(ParameterSetName = "NamedPipe")]
     [string]
     $DebugServicePipeName = $null,
 
-    [Parameter(ParameterSetName="NamedPipeSimplex")]
+    [Parameter(ParameterSetName = "NamedPipeSimplex")]
     [switch]
     $SplitInOutPipes,
 
-    [Parameter(ParameterSetName="NamedPipeSimplex")]
+    [Parameter(ParameterSetName = "NamedPipeSimplex")]
     [string]
     $LanguageServiceInPipeName,
 
-    [Parameter(ParameterSetName="NamedPipeSimplex")]
+    [Parameter(ParameterSetName = "NamedPipeSimplex")]
     [string]
     $LanguageServiceOutPipeName,
 
-    [Parameter(ParameterSetName="NamedPipeSimplex")]
+    [Parameter(ParameterSetName = "NamedPipeSimplex")]
     [string]
     $DebugServiceInPipeName = $null,
 
-    [Parameter(ParameterSetName="NamedPipeSimplex")]
+    [Parameter(ParameterSetName = "NamedPipeSimplex")]
     [string]
     $DebugServiceOutPipeName = $null
 )

src/PowerShellEditorServices.Hosting/Commands/StartEditorServicesCommand.cs

@@ -182,6 +182,12 @@ public StartEditorServicesCommand()
         [Parameter]
         public SwitchParameter DebugServiceOnly { get; set; }
 
+        /// <summary>
+        /// When set, do not enable debug adapter, only the LSP service.
+        /// </summary>
+        [Parameter]
+        public SwitchParameter LanguageServiceOnly { get; set; }
+
         /// <summary>
         /// When set with a debug build, startup will wait for a debugger to attach.
         /// </summary>
@@ -465,6 +471,11 @@ private ITransportConfig GetDebugServiceTransport()
         {
             _logger.Log(PsesLogLevel.Diagnostic, "Configuring debug transport");
 
+            if(LanguageServiceOnly)
+            {
+                _logger.Log(PsesLogLevel.Diagnostic, "No Debug transport: PSES is language service only");
+                return null;
+            }
             if (Stdio)
             {
                 if (DebugServiceOnly)

src/PowerShellEditorServices/Server/PsesLanguageServer.cs

@@ -73,6 +73,7 @@ public PsesLanguageServer(
         /// <returns>A task that completes when the server is ready and listening.</returns>
         public async Task StartAsync()
         {
+            
             LanguageServer = await OmniSharp.Extensions.LanguageServer.Server.LanguageServer.From(options =>
             {
                 options