Visual Studio 2017 extension: Displaying Light Bulb Suggestions

extension.fs

// Example follows this, translated to FSharp:
// https://msdn.microsoft.com/en-us/library/dn903708.aspx 

// Just instead of copy&pasting C#, add a new F# class library and paste this code to there,
// then add that to reference to your C#-project.

// If you want to deploy without C# project, see e.g. this:
// You need to use some VSIX-package to deploy the code:
// https://github.com/fsharp-vsix/FsVSIX

// One more thing to get this to work: Open the source.extension.vsixmanifest file
// Go to Assets -> Edit -> Project and change your fsharp dll to dropdown.
// This tells MEF to which dll to use to inject dependencies to Visual Studio.
// Corresponding XML: 
// <Asset Type="Microsoft.VisualStudio.MefComponent" d:Source="Project" d:ProjectName="..." Path="|...|" />

#if INTERACTIVE
#I @"C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\VSSDK\VisualStudioIntegration\Common\Assemblies\v4.0\"

#r "Microsoft.VisualStudio.Imaging.Interop.14.0.DesignTime.dll"
#r "Microsoft.VisualStudio.Language.Intellisense.dll"
#r "Microsoft.VisualStudio.CoreUtility.dll"
#r "Microsoft.VisualStudio.Text.Data.dll"
#r "Microsoft.VisualStudio.Text.Logic.dll"
#r "Microsoft.VisualStudio.Text.UI.dll"
#r "Microsoft.VisualStudio.Text.UI.Wpf.dll"

#I @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6\"

#r "PresentationFramework.Core.dll"
#r "PresentationFramework.dll"
#r "WindowsBase.dll"

#r "System.ComponentModel.Composition.dll"


#endif
namespace VisualStudioTooltips

open Microsoft.VisualStudio.Imaging.Interop
open System.Windows
open System.Windows.Controls
open System.Windows.Documents
open Microsoft.VisualStudio.Text

open System.Threading.Tasks

open System
open System.Collections.Generic
open Microsoft.VisualStudio.Language.Intellisense
open Microsoft.VisualStudio.Text.Editor
open Microsoft.VisualStudio.Text.Operations
open Microsoft.VisualStudio.Utilities
open System.ComponentModel.Composition

type internal UpperCaseSuggestedAction (span:ITrackingSpan) =
    let snapshot = span.TextBuffer.CurrentSnapshot
    let upper = span.GetText(snapshot).ToUpper()
    let display = sprintf "Convert '%s' to upper case" (span.GetText snapshot)
    
    interface ISuggestedAction with

        member __.GetPreviewAsync (_) =
            let textBlock = TextBlock(Padding = Thickness(5.)) 
            textBlock.Inlines.Add (Run upper)
            Task.FromResult<obj> textBlock
    
        member __.GetActionSetsAsync (_) =
            Task.FromResult<IEnumerable<SuggestedActionSet>>(null)

        member val HasActionSets = false with get
        member val DisplayText = display with get
        member val IconMoniker = Unchecked.defaultof<ImageMoniker> with get
        member val IconAutomationText = Unchecked.defaultof<string> with get
        member val InputGestureText = Unchecked.defaultof<string> with get
        member val HasPreview = true with get

        member __.Invoke (_) =
            span.TextBuffer.Replace(span.GetSpan(snapshot).Span, upper) |> ignore
            ()

        member __.TryGetTelemetryId
                ([<System.Runtime.InteropServices.Out>] telemetryId : Guid byref) =
            telemetryId <- Guid.Empty
            false

        member __.Dispose() = ()

//type internal LowerCaseSuggestedAction : ISuggestedAction

[<Export(typeof<ISuggestedActionsSourceProvider>)>]
[<Name "Test Suggested Actions">]
[<ContentType "text">]
type internal TestSuggestedActionsSourceProvider() as this = 
    [<Import(typeof<ITextStructureNavigatorSelectorService>)>]  
    member val NavigatorService = 
        Unchecked.defaultof<ITextStructureNavigatorSelectorService> with get, set

    interface ISuggestedActionsSourceProvider with 
        member this.CreateSuggestedActionsSource(textView, textBuffer) =
            if textBuffer = null && textView = null then
                Unchecked.defaultof<ISuggestedActionsSource>
            else 
                new TestSuggestedActionsSource(this, textView, textBuffer)
                :> ISuggestedActionsSource


and internal TestSuggestedActionsSource
        ( prov:TestSuggestedActionsSourceProvider, 
          textView:ITextView, textBuffer:ITextBuffer) =

    let event = DelegateEvent<EventHandler<EventArgs>>()

    let tryGetWordUnderCaret() =
        let caret = textView.Caret
        if caret.Position.BufferPosition.Position <= 0 then
            false, Unchecked.defaultof<TextExtent>
        else  
        let point = caret.Position.BufferPosition - 1
        let navigator = prov.NavigatorService.GetTextStructureNavigator textBuffer
        true, navigator.GetExtentOfWord point

    interface ISuggestedActionsSource with 

        member __.HasSuggestedActionsAsync(requestedActionCategories, range, cToken) =
            System.Threading.Tasks.Task.Factory.StartNew(fun () ->
                let ok, extent = tryGetWordUnderCaret()
                if ok then  // don't display the action if the extent has whitespace  
                    extent.IsSignificant
                else false
            )

        member __.GetSuggestedActions(requestedActionCategories, range, cToken) =
            let ok, extent = tryGetWordUnderCaret()
            if ok && extent.IsSignificant then
                let trackingSpan = 
                    range.Snapshot.CreateTrackingSpan(
                        extent.Span.Span, SpanTrackingMode.EdgeInclusive)
                use upperAction = new UpperCaseSuggestedAction(trackingSpan)
                //let lowerAction = LowerCaseSuggestedAction trackingSpan :> ISuggestedAction
                [| (SuggestedActionSet [| upperAction; (* lowerAction *) |]) |] 
                :> IEnumerable<SuggestedActionSet>
            else 
                [||] :> IEnumerable<SuggestedActionSet>

        [<CLIEvent>]
        member __.SuggestedActionsChanged = event.Publish

        member __.TryGetTelemetryId(
                [<System.Runtime.InteropServices.Out>] telemetryId : Guid byref) =
            telemetryId <- Guid.Empty
            false

    interface IDisposable with 
        member __.Dispose() = ()