Democratizing code fixes - part two

vsintegration/src/FSharp.Editor/CodeFix/AddInstanceMemberParameter.fs

@@ -3,7 +3,6 @@
 namespace Microsoft.VisualStudio.FSharp.Editor
 
 open System.Composition
-open System.Threading.Tasks
 open System.Collections.Immutable
 
 open Microsoft.CodeAnalysis.Text
@@ -17,16 +16,17 @@ type internal FSharpAddInstanceMemberParameterCodeFixProvider() =
 
     static let title = SR.AddMissingInstanceMemberParameter()
 
-    interface IFSharpCodeFix with
-        member _.GetChangesAsync _ span =
-            let changes = [ TextChange(TextSpan(span.Start, 0), "x.") ]
-            CancellableTask.singleton (title, changes)
-
     override _.FixableDiagnosticIds = ImmutableArray.Create("FS0673")
 
-    override this.RegisterCodeFixesAsync context : Task =
-        cancellableTask {
-            let! title, changes = (this :> IFSharpCodeFix).GetChangesAsync context.Document context.Span
-            context.RegisterFsharpFix(CodeFix.AddInstanceMemberParameter, title, changes)
-        }
-        |> CancellableTask.startAsTask context.CancellationToken
+    override this.RegisterCodeFixesAsync context = context.RegisterFsharpFix(this)
+
+    interface IFSharpCodeFixProvider with
+        member _.GetCodeFixIfAppliesAsync _ span =
+            let codeFix =
+                {
+                    Name = CodeFix.AddInstanceMemberParameter
+                    Message = title
+                    Changes = [ TextChange(TextSpan(span.Start, 0), "x.") ]
+                }
+
+            CancellableTask.singleton (Some codeFix)

vsintegration/src/FSharp.Editor/CodeFix/AddMissingRecToMutuallyRecFunctions.fs

@@ -5,16 +5,11 @@ namespace Microsoft.VisualStudio.FSharp.Editor
 open System
 open System.Collections.Immutable
 open System.Composition
-open System.Threading
 
 open Microsoft.CodeAnalysis.Text
 open Microsoft.CodeAnalysis.CodeFixes
 
-open FSharp.Compiler
-open FSharp.Compiler.CodeAnalysis
-
-open Microsoft.CodeAnalysis
-open Microsoft.CodeAnalysis.CodeActions
+open CancellableTasks
 
 [<ExportCodeFixProvider(FSharpConstants.FSharpLanguageName, Name = CodeFix.AddMissingRecToMutuallyRecFunctions); Shared>]
 type internal FSharpAddMissingRecToMutuallyRecFunctionsCodeFixProvider [<ImportingConstructor>] () =
@@ -24,48 +19,48 @@ type internal FSharpAddMissingRecToMutuallyRecFunctionsCodeFixProvider [<Importi
 
     override _.FixableDiagnosticIds = ImmutableArray.Create("FS0576")
 
-    override _.RegisterCodeFixesAsync context =
-        asyncMaybe {
-            let! defines, langVersion =
-                context.Document.GetFSharpCompilationDefinesAndLangVersionAsync(
-                    nameof (FSharpAddMissingRecToMutuallyRecFunctionsCodeFixProvider)
-                )
-                |> liftAsync
+    override this.RegisterCodeFixesAsync context = context.RegisterFsharpFix(this)
 
-            let! sourceText = context.Document.GetTextAsync(context.CancellationToken)
+    interface IFSharpCodeFixProvider with
+        member _.GetCodeFixIfAppliesAsync document span =
+            cancellableTask {
+                let! cancellationToken = CancellableTask.getCurrentCancellationToken ()
 
-            let funcStartPos =
-                let rec loop ch pos =
-                    if not (Char.IsWhiteSpace(ch)) then
-                        pos
-                    else
-                        loop sourceText.[pos + 1] (pos + 1)
+                let! defines, langVersion =
+                    document.GetFSharpCompilationDefinesAndLangVersionAsync(
+                        nameof (FSharpAddMissingRecToMutuallyRecFunctionsCodeFixProvider)
+                    )
 
-                loop sourceText.[context.Span.End + 1] (context.Span.End + 1)
+                let! sourceText = document.GetTextAsync(cancellationToken)
 
-            let! funcLexerSymbol =
-                Tokenizer.getSymbolAtPosition (
-                    context.Document.Id,
-                    sourceText,
-                    funcStartPos,
-                    context.Document.FilePath,
-                    defines,
-                    SymbolLookupKind.Greedy,
-                    false,
-                    false,
-                    Some langVersion,
-                    context.CancellationToken
-                )
+                let funcStartPos =
+                    let rec loop ch pos =
+                        if not (Char.IsWhiteSpace(ch)) then
+                            pos
+                        else
+                            loop sourceText.[pos + 1] (pos + 1)
 
-            let! funcNameSpan = RoslynHelpers.TryFSharpRangeToTextSpan(sourceText, funcLexerSymbol.Range)
-            let funcName = sourceText.GetSubText(funcNameSpan).ToString()
+                    loop sourceText.[span.End + 1] (span.End + 1)
 
-            do
-                context.RegisterFsharpFix(
-                    CodeFix.AddMissingRecToMutuallyRecFunctions,
-                    String.Format(titleFormat, funcName),
-                    [| TextChange(TextSpan(context.Span.End, 0), " rec") |]
-                )
-        }
-        |> Async.Ignore
-        |> RoslynHelpers.StartAsyncUnitAsTask(context.CancellationToken)
+                return
+                    Tokenizer.getSymbolAtPosition (
+                        document.Id,
+                        sourceText,
+                        funcStartPos,
+                        document.FilePath,
+                        defines,
+                        SymbolLookupKind.Greedy,
+                        false,
+                        false,
+                        Some langVersion,
+                        cancellationToken
+                    )
+                    |> Option.bind (fun funcLexerSymbol -> RoslynHelpers.TryFSharpRangeToTextSpan(sourceText, funcLexerSymbol.Range))
+                    |> Option.map (fun funcNameSpan -> sourceText.GetSubText(funcNameSpan).ToString())
+                    |> Option.map (fun funcName ->
+                        {
+                            Name = CodeFix.AddMissingRecToMutuallyRecFunctions
+                            Message = String.Format(titleFormat, funcName)
+                            Changes = [ TextChange(TextSpan(span.End, 0), " rec") ]
+                        })
+            }

vsintegration/src/FSharp.Editor/CodeFix/ChangeToUpcast.fs

@@ -3,7 +3,6 @@
 namespace Microsoft.VisualStudio.FSharp.Editor
 
 open System.Composition
-open System.Threading.Tasks
 open System.Collections.Immutable
 
 open Microsoft.CodeAnalysis.Text
@@ -17,8 +16,10 @@ type internal FSharpChangeToUpcastCodeFixProvider() =
 
     override _.FixableDiagnosticIds = ImmutableArray.Create("FS3198")
 
-    interface IFSharpCodeFix with
-        member _.GetChangesAsync document span =
+    override this.RegisterCodeFixesAsync context = context.RegisterFsharpFix(this)
+
+    interface IFSharpCodeFixProvider with
+        member _.GetCodeFixIfAppliesAsync document span =
             cancellableTask {
                 let! cancellationToken = CancellableTask.getCurrentCancellationToken ()
 
@@ -29,33 +30,32 @@ type internal FSharpChangeToUpcastCodeFixProvider() =
                 let isDowncastOperator = text.Contains(":?>")
                 let isDowncastKeyword = text.Contains("downcast")
 
-                let changes =
-                    [
-                        if
-                            (isDowncastOperator || isDowncastKeyword)
-                            && not (isDowncastOperator && isDowncastKeyword)
-                        then
-                            let replacement =
-                                if isDowncastOperator then
-                                    text.Replace(":?>", ":>")
-                                else
-                                    text.Replace("downcast", "upcast")
-
-                            TextChange(span, replacement)
-                    ]
-
-                let title =
-                    if isDowncastOperator then
-                        SR.UseUpcastOperator()
-                    else
-                        SR.UseUpcastKeyword()
-
-                return title, changes
+                if
+                    (isDowncastOperator || isDowncastKeyword)
+                    && not (isDowncastOperator && isDowncastKeyword)
+                then
+                    let replacement =
+                        if isDowncastOperator then
+                            text.Replace(":?>", ":>")
+                        else
+                            text.Replace("downcast", "upcast")
+
+                    let changes = [ TextChange(span, replacement) ]
+
+                    let title =
+                        if isDowncastOperator then
+                            SR.UseUpcastOperator()
+                        else
+                            SR.UseUpcastKeyword()
+
+                    let codeFix =
+                        {
+                            Name = CodeFix.ChangeToUpcast
+                            Message = title
+                            Changes = changes
+                        }
+
+                    return Some codeFix
+                else
+                    return None
             }
-
-    override this.RegisterCodeFixesAsync context : Task =
-        cancellableTask {
-            let! title, changes = (this :> IFSharpCodeFix).GetChangesAsync context.Document context.Span
-            context.RegisterFsharpFix(CodeFix.ChangeToUpcast, title, changes)
-        }
-        |> CancellableTask.startAsTask context.CancellationToken

vsintegration/src/FSharp.Editor/CodeFix/CodeFixHelpers.fs

@@ -2,9 +2,7 @@
 
 namespace Microsoft.VisualStudio.FSharp.Editor
 
-open System
 open System.Threading
-open System.Threading.Tasks
 open System.Collections.Immutable
 open System.Diagnostics
 
@@ -15,6 +13,8 @@ open Microsoft.CodeAnalysis.CodeFixes
 open Microsoft.CodeAnalysis.CodeActions
 open Microsoft.VisualStudio.FSharp.Editor.Telemetry
 
+open CancellableTasks
+
 [<RequireQualifiedAccess>]
 module internal CodeFixHelpers =
     let private reportCodeFixTelemetry
@@ -80,3 +80,11 @@ module internal CodeFixExtensions =
 
             let diag = diagnostics |> Option.defaultValue ctx.Diagnostics
             ctx.RegisterCodeFix(codeAction, diag)
+
+        member ctx.RegisterFsharpFix(codeFix: IFSharpCodeFixProvider) =
+            cancellableTask {
+                match! codeFix.GetCodeFixIfAppliesAsync ctx.Document ctx.Span with
+                | Some codeFix -> ctx.RegisterFsharpFix(codeFix.Name, codeFix.Message, codeFix.Changes)
+                | None -> ()
+            }
+            |> CancellableTask.startAsTask ctx.CancellationToken

vsintegration/src/FSharp.Editor/CodeFix/ConvertToAnonymousRecord.fs

@@ -3,7 +3,6 @@
 namespace Microsoft.VisualStudio.FSharp.Editor
 
 open System.Composition
-open System.Threading.Tasks
 open System.Collections.Immutable
 
 open Microsoft.CodeAnalysis.Text
@@ -19,8 +18,10 @@ type internal FSharpConvertToAnonymousRecordCodeFixProvider [<ImportingConstruct
 
     override _.FixableDiagnosticIds = ImmutableArray.Create("FS0039")
 
-    interface IFSharpCodeFix with
-        member _.GetChangesAsync document span =
+    override this.RegisterCodeFixesAsync context = context.RegisterFsharpFix(this)
+
+    interface IFSharpCodeFixProvider with
+        member _.GetCodeFixIfAppliesAsync document span =
             cancellableTask {
                 let! cancellationToken = CancellableTask.getCurrentCancellationToken ()
 
@@ -31,22 +32,17 @@ type internal FSharpConvertToAnonymousRecordCodeFixProvider [<ImportingConstruct
                 let errorRange =
                     RoslynHelpers.TextSpanToFSharpRange(document.FilePath, span, sourceText)
 
-                let changes =
+                return
                     parseResults.TryRangeOfRecordExpressionContainingPos errorRange.Start
                     |> Option.bind (fun range -> RoslynHelpers.TryFSharpRangeToTextSpan(sourceText, range))
                     |> Option.map (fun span ->
-                        [
-                            TextChange(TextSpan(span.Start + 1, 0), "|")
-                            TextChange(TextSpan(span.End - 1, 0), "|")
-                        ])
-                    |> Option.defaultValue []
-
-                return title, changes
+                        {
+                            Name = CodeFix.ConvertToAnonymousRecord
+                            Message = title
+                            Changes =
+                                [
+                                    TextChange(TextSpan(span.Start + 1, 0), "|")
+                                    TextChange(TextSpan(span.End - 1, 0), "|")
+                                ]
+                        })
             }
-
-    override this.RegisterCodeFixesAsync context : Task =
-        cancellableTask {
-            let! title, changes = (this :> IFSharpCodeFix).GetChangesAsync context.Document context.Span
-            return context.RegisterFsharpFix(CodeFix.ConvertToAnonymousRecord, title, changes)
-        }
-        |> CancellableTask.startAsTask context.CancellationToken

vsintegration/src/FSharp.Editor/CodeFix/IFSharpCodeFix.fs

@@ -7,5 +7,12 @@ open Microsoft.CodeAnalysis.Text
 
 open CancellableTasks
 
-type IFSharpCodeFix =
-    abstract member GetChangesAsync: document: Document -> span: TextSpan -> CancellableTask<string * TextChange list>
+type FSharpCodeFix =
+    {
+        Name: string
+        Message: string
+        Changes: TextChange list
+    }
+
+type IFSharpCodeFixProvider =
+    abstract member GetCodeFixIfAppliesAsync: document: Document -> span: TextSpan -> CancellableTask<FSharpCodeFix option>

vsintegration/src/FSharp.Editor/CodeFix/RemoveReturnOrYield.fs

@@ -8,40 +8,44 @@ open System.Collections.Immutable
 open Microsoft.CodeAnalysis.Text
 open Microsoft.CodeAnalysis.CodeFixes
 
+open CancellableTasks
+
 [<ExportCodeFixProvider(FSharpConstants.FSharpLanguageName, Name = CodeFix.RemoveReturnOrYield); Shared>]
 type internal FSharpRemoveReturnOrYieldCodeFixProvider [<ImportingConstructor>] () =
     inherit CodeFixProvider()
 
-    override _.FixableDiagnosticIds = ImmutableArray.Create("FS0748", "FS0747")
+    override _.FixableDiagnosticIds = ImmutableArray.Create("FS0747", "FS0748")
+
+    override this.RegisterCodeFixesAsync context = context.RegisterFsharpFix(this)
 
-    override _.RegisterCodeFixesAsync context =
-        asyncMaybe {
-            let! parseResults =
-                context.Document.GetFSharpParseResultsAsync(nameof (FSharpRemoveReturnOrYieldCodeFixProvider))
-                |> liftAsync
+    interface IFSharpCodeFixProvider with
+        member _.GetCodeFixIfAppliesAsync document span =
+            cancellableTask {
+                let! cancellationToken = CancellableTask.getCurrentCancellationToken ()
 
-            let! sourceText = context.Document.GetTextAsync(context.CancellationToken)
+                let! parseResults = document.GetFSharpParseResultsAsync(nameof (FSharpRemoveReturnOrYieldCodeFixProvider))
 
-            let errorRange =
-                RoslynHelpers.TextSpanToFSharpRange(context.Document.FilePath, context.Span, sourceText)
+                let! sourceText = document.GetTextAsync(cancellationToken)
 
-            let! exprRange = parseResults.TryRangeOfExprInYieldOrReturn errorRange.Start
-            let! exprSpan = RoslynHelpers.TryFSharpRangeToTextSpan(sourceText, exprRange)
+                let errorRange =
+                    RoslynHelpers.TextSpanToFSharpRange(document.FilePath, span, sourceText)
 
-            let title =
-                let text = sourceText.GetSubText(context.Span).ToString()
+                return
+                    parseResults.TryRangeOfExprInYieldOrReturn errorRange.Start
+                    |> Option.bind (fun exprRange -> RoslynHelpers.TryFSharpRangeToTextSpan(sourceText, exprRange))
+                    |> Option.map (fun exprSpan -> [ TextChange(span, sourceText.GetSubText(exprSpan).ToString()) ])
+                    |> Option.map (fun changes ->
+                        let title =
+                            let text = sourceText.GetSubText(span).ToString()
 
-                if text.StartsWith("return!") then SR.RemoveReturnBang()
-                elif text.StartsWith("return") then SR.RemoveReturn()
-                elif text.StartsWith("yield!") then SR.RemoveYieldBang()
-                else SR.RemoveYield()
+                            if text.StartsWith("return!") then SR.RemoveReturnBang()
+                            elif text.StartsWith("return") then SR.RemoveReturn()
+                            elif text.StartsWith("yield!") then SR.RemoveYieldBang()
+                            else SR.RemoveYield()
 
-            do
-                context.RegisterFsharpFix(
-                    CodeFix.RemoveReturnOrYield,
-                    title,
-                    [| TextChange(context.Span, sourceText.GetSubText(exprSpan).ToString()) |]
-                )
-        }
-        |> Async.Ignore
-        |> RoslynHelpers.StartAsyncUnitAsTask(context.CancellationToken)
+                        {
+                            Name = CodeFix.RemoveReturnOrYield
+                            Message = title
+                            Changes = changes
+                        })
+            }