Enable support for PowerShell v3 and v4

This change finishes our PowerShell v3 and v4 support by conditionally
changing behavior for those versions.  This works by using an interface
facade in front of any version-specific behavior so that the CLR doesn't
try to resolve method names that aren't available in a particular version.

Resolves #73.

Author: daviwil

src/PowerShellEditorServices.Protocol/Server/DebugAdapter.cs

@@ -295,7 +295,14 @@ protected Task HandlePauseRequest(
             object pauseParams,
             RequestContext<object> requestContext)
         {
-            editorSession.DebugService.Break();
+            try
+            {
+                editorSession.DebugService.Break();
+            }
+            catch (NotSupportedException e)
+            {
+                return requestContext.SendError(e.Message);
+            }
 
             // This request is responded to by sending the "stopped" event
             return Task.FromResult(true);

src/PowerShellEditorServices/PowerShellEditorServices.csproj

@@ -98,8 +98,12 @@
     <Compile Include="Console\ChoiceDetails.cs" />
     <Compile Include="Session\EditorSession.cs" />
     <Compile Include="Console\IConsoleHost.cs" />
+    <Compile Include="Session\IVersionSpecificOperations.cs" />
     <Compile Include="Session\OutputType.cs" />
     <Compile Include="Session\OutputWrittenEventArgs.cs" />
+    <Compile Include="Session\PowerShell3Operations.cs" />
+    <Compile Include="Session\PowerShell4Operations.cs" />
+    <Compile Include="Session\PowerShell5Operations.cs" />
     <Compile Include="Session\PowerShellExecutionResult.cs" />
     <Compile Include="Session\PowerShellContext.cs" />
     <Compile Include="Session\PowerShellContextState.cs" />

src/PowerShellEditorServices/Session/EditorSession.cs

@@ -5,9 +5,11 @@
 
 using Microsoft.PowerShell.EditorServices.Console;
 using Microsoft.PowerShell.EditorServices.Utility;
+using System;
 using System.IO;
 using System.Management.Automation;
 using System.Management.Automation.Runspaces;
+using System.Reflection;
 using System.Threading;
 
 namespace Microsoft.PowerShell.EditorServices
@@ -66,17 +68,34 @@ public void StartSession()
             this.DebugService = new DebugService(this.PowerShellContext);
             this.ConsoleService = new ConsoleService(this.PowerShellContext);
 
-            // AnalysisService will throw FileNotFoundException if
-            // Script Analyzer binaries are not included.
-            try
+            // Only enable the AnalysisService if the machine has PowerShell
+            // v5 installed.  Script Analyzer works on earlier PowerShell
+            // versions but our hard dependency on their binaries complicates
+            // the deployment and assembly loading since we would have to
+            // conditionally load the binaries for v3/v4 support.  This problem
+            // will be solved in the future by using Script Analyzer as a
+            // module rather than an assembly dependency.
+            if (this.PowerShellContext.PowerShellVersion.Major >= 5)
             {
-                this.AnalysisService = new AnalysisService();
+                // AnalysisService will throw FileNotFoundException if
+                // Script Analyzer binaries are not included.
+                try
+                {
+                    this.AnalysisService = new AnalysisService();
+                }
+                catch (FileNotFoundException)
+                {
+                    Logger.Write(
+                        LogLevel.Warning,
+                        "Script Analyzer binaries not found, AnalysisService will be disabled.");
+                }
             }
-            catch (FileNotFoundException)
+            else
             {
                 Logger.Write(
-                    LogLevel.Warning,
-                    "Script Analyzer binaries not found, AnalysisService will be disabled.");
+                    LogLevel.Normal,
+                    "Script Analyzer cannot be loaded due to unsupported PowerShell version " +
+                    this.PowerShellContext.PowerShellVersion.ToString());
             }
 
             // Create a workspace to contain open files

src/PowerShellEditorServices/Session/IVersionSpecificOperations.cs

@@ -0,0 +1,25 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Collections.Generic;
+using System.Management.Automation;
+using System.Management.Automation.Runspaces;
+
+namespace Microsoft.PowerShell.EditorServices.Session
+{
+    internal interface IVersionSpecificOperations
+    {
+        void ConfigureDebugger(Runspace runspace);
+
+        void PauseDebugger(Runspace runspace);
+
+        IEnumerable<TResult> ExecuteCommandInDebugger<TResult>(
+            PowerShellContext powerShellContext,
+            Runspace currentRunspace,
+            PSCommand psCommand,
+            bool sendOutputToHost);
+    }
+}
+

src/PowerShellEditorServices/Session/PowerShell3Operations.cs

@@ -0,0 +1,62 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Management.Automation;
+using System.Management.Automation.Runspaces;
+
+namespace Microsoft.PowerShell.EditorServices.Session
+{
+    internal class PowerShell3Operations : IVersionSpecificOperations
+    {
+        public void ConfigureDebugger(Runspace runspace)
+        {
+            // The debugger has no SetDebugMode in PowerShell v3.
+        }
+
+        public void PauseDebugger(Runspace runspace)
+        {
+            // The debugger cannot be paused in PowerShell v3.
+            throw new NotSupportedException("Debugger cannot be paused in PowerShell v3");
+        }
+
+        public IEnumerable<TResult> ExecuteCommandInDebugger<TResult>(
+            PowerShellContext powerShellContext,
+            Runspace currentRunspace,
+            PSCommand psCommand,
+            bool sendOutputToHost)
+        {
+            IEnumerable<TResult> executionResult = null;
+
+            using (var nestedPipeline = currentRunspace.CreateNestedPipeline())
+            {
+                foreach (var command in psCommand.Commands)
+                {
+                    nestedPipeline.Commands.Add(command);
+                }
+
+                executionResult =
+                    nestedPipeline
+                        .Invoke()
+                        .Select(pso => pso.BaseObject)
+                        .Cast<TResult>();
+            }
+
+            // Write the output to the host if necessary
+            if (sendOutputToHost)
+            {
+                foreach (var line in executionResult)
+                {
+                    powerShellContext.WriteOutput(line.ToString(), true);
+                }
+            }
+
+            return executionResult;
+        }
+    }
+}
+

src/PowerShellEditorServices/Session/PowerShell4Operations.cs

@@ -0,0 +1,65 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Management.Automation;
+using System.Management.Automation.Runspaces;
+
+namespace Microsoft.PowerShell.EditorServices.Session
+{
+    internal class PowerShell4Operations : IVersionSpecificOperations
+    {
+        public void ConfigureDebugger(Runspace runspace)
+        {
+#if !PowerShellv3
+            runspace.Debugger.SetDebugMode(DebugModes.LocalScript | DebugModes.RemoteScript);
+#endif
+        }
+
+        public virtual void PauseDebugger(Runspace runspace)
+        {
+            // The debugger cannot be paused in PowerShell v4.
+            throw new NotSupportedException("Debugger cannot be paused in PowerShell v4");
+        }
+
+        public IEnumerable<TResult> ExecuteCommandInDebugger<TResult>(
+            PowerShellContext powerShellContext,
+            Runspace currentRunspace,
+            PSCommand psCommand,
+            bool sendOutputToHost)
+        {
+            PSDataCollection<PSObject> outputCollection = new PSDataCollection<PSObject>();
+
+#if !PowerShellv3
+            if (sendOutputToHost)
+            {
+                outputCollection.DataAdded +=
+                    (obj, e) =>
+                    {
+                        for (int i = e.Index; i < outputCollection.Count; i++)
+                        {
+                            powerShellContext.WriteOutput(
+                                outputCollection[i].ToString(),
+                                true);
+                        }
+                    };
+            }
+
+            DebuggerCommandResults commandResults =
+                currentRunspace.Debugger.ProcessCommand(
+                    psCommand,
+                    outputCollection);
+#endif
+
+            return
+                outputCollection
+                    .Select(pso => pso.BaseObject)
+                    .Cast<TResult>();
+        }
+    }
+}
+

src/PowerShellEditorServices/Session/PowerShell5Operations.cs

@@ -0,0 +1,20 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Management.Automation.Runspaces;
+
+namespace Microsoft.PowerShell.EditorServices.Session
+{
+    internal class PowerShell5Operations : PowerShell4Operations
+    {
+        public override void PauseDebugger(Runspace runspace)
+        {
+#if !PowerShellv3 && !PowerShellv4
+            runspace.Debugger.SetDebuggerStepMode(true);
+#endif
+        }
+    }
+}
+