#11793 Simplify tag to self-closing code action

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Language/Syntax/SyntaxList`1.cs

@@ -440,6 +440,34 @@ public bool Any()
         return Node != null;
     }
 
+    public bool Any(Func<TNode, bool> predicate)
+    {
+        foreach (var node in this)
+        {
+            if (predicate(node))
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public SyntaxList<TNode> Where(Func<TNode, bool> predicate)
+    {
+        using var builder = new PooledArrayBuilder<TNode>(Count);
+
+        foreach (var node in this)
+        {
+            if (predicate(node))
+            {
+                builder.Add(node);
+            }
+        }
+
+        return builder.ToList();
+    }
+
     // for debugging
 #pragma warning disable IDE0051 // Remove unused private members
     private TNode[] Nodes => [.. this];

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Extensions/IServiceCollectionExtensions.cs

@@ -156,6 +156,8 @@ public static void AddCodeActionsServices(this IServiceCollection services)
         services.AddSingleton<IRazorCodeActionResolver, PromoteUsingCodeActionResolver>();
         services.AddSingleton<IRazorCodeActionProvider, WrapAttributesCodeActionProvider>();
         services.AddSingleton<IRazorCodeActionResolver, WrapAttributesCodeActionResolver>();
+        services.AddSingleton<IRazorCodeActionProvider, SimplifyTagToSelfClosingCodeActionProvider>();
+        services.AddSingleton<IRazorCodeActionResolver, SimplifyTagToSelfClosingCodeActionResolver>();
 
         // Html Code actions
         services.AddSingleton<IHtmlCodeActionProvider, HtmlCodeActionProvider>();

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Models/SimplifyComponentCodeActionParams.cs

@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Text.Json.Serialization;
+
+namespace Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+
+internal sealed class SimplifyTagToSelfClosingCodeActionParams
+{
+    [JsonPropertyName("startTagCloseAngleIndex")]
+    public int StartTagCloseAngleIndex { get; set; }
+
+    [JsonPropertyName("endTagCloseAngleIndex")]
+    public int EndTagCloseAngleIndex { get; set; }
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/RazorCodeActionFactory.cs

@@ -15,6 +15,7 @@ internal static class RazorCodeActionFactory
     private readonly static Guid s_createComponentFromTagTelemetryId = new("a28e0baa-a4d5-4953-a817-1db586035841");
     private readonly static Guid s_createExtractToCodeBehindTelemetryId = new("f63167f7-fdc6-450f-8b7b-b240892f4a27");
     private readonly static Guid s_createExtractToComponentTelemetryId = new("af67b0a3-f84b-4808-97a7-b53e85b22c64");
+    private readonly static Guid s_simplifyComponentTelemetryId = new("2207f68c-419e-4baa-8493-2e7769e5c91d");
     private readonly static Guid s_generateMethodTelemetryId = new("c14fa003-c752-45fc-bb29-3a123ae5ecef");
     private readonly static Guid s_generateAsyncMethodTelemetryId = new("9058ca47-98e2-4f11-bf7c-a16a444dd939");
     private readonly static Guid s_promoteUsingDirectiveTelemetryId = new("751f9012-e37b-444a-9211-b4ebce91d96e");
@@ -111,6 +112,19 @@ public static RazorVSInternalCodeAction CreateExtractToComponent(RazorCodeAction
         return codeAction;
     }
 
+    public static RazorVSInternalCodeAction CreateSimplifyTagToSelfClosing(RazorCodeActionResolutionParams resolutionParams)
+    {
+        var data = JsonSerializer.SerializeToElement(resolutionParams);
+        var codeAction = new RazorVSInternalCodeAction()
+        {
+            Title = SR.Simplify_Tag_To_SelfClosing_Title,
+            Data = data,
+            TelemetryId = s_simplifyComponentTelemetryId,
+            Name = LanguageServerConstants.CodeActions.SimplifyTagToSelfClosingAction,
+        };
+        return codeAction;
+    }
+
     public static RazorVSInternalCodeAction CreateGenerateMethod(VSTextDocumentIdentifier textDocument, Uri? delegatedDocumentUri, string methodName, string? eventParameterType)
     {
         var @params = new GenerateMethodCodeActionParams

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/SimplifyTagToSelfClosingCodeActionProvider.cs

@@ -0,0 +1,137 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.AspNetCore.Razor.Language.Components;
+using Microsoft.AspNetCore.Razor.Language.Syntax;
+using Microsoft.AspNetCore.Razor.Threading;
+using Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+using Microsoft.CodeAnalysis.Razor.Protocol;
+
+namespace Microsoft.CodeAnalysis.Razor.CodeActions.Razor;
+
+internal class SimplifyTagToSelfClosingCodeActionProvider : IRazorCodeActionProvider
+{
+    public Task<ImmutableArray<RazorVSInternalCodeAction>> ProvideAsync(RazorCodeActionContext context, CancellationToken cancellationToken)
+    {
+        if (context.HasSelection)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Make sure we're in the right kind and part of file
+        if (!FileKinds.IsComponent(context.CodeDocument.FileKind))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        if (context.LanguageKind != RazorLanguageKind.Html)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Caret must be inside a markup element
+        if (context.ContainsDiagnostic(ComponentDiagnosticFactory.UnexpectedMarkupElement.Id) ||
+            context.ContainsDiagnostic(ComponentDiagnosticFactory.UnexpectedClosingTag.Id))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        var syntaxTree = context.CodeDocument.GetSyntaxTree();
+        if (syntaxTree?.Root is null)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        var owner = syntaxTree.Root.FindInnermostNode(context.StartAbsoluteIndex, includeWhitespace: false)?.FirstAncestorOrSelf<MarkupTagHelperElementSyntax>();
+        if (owner is not MarkupTagHelperElementSyntax markupElementSyntax)
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Check whether the code action is applicable to the element
+        if (!IsApplicableTo(markupElementSyntax))
+        {
+            return SpecializedTasks.EmptyImmutableArray<RazorVSInternalCodeAction>();
+        }
+
+        // Provide code action to simplify
+        var actionParams = new SimplifyTagToSelfClosingCodeActionParams
+        {
+            StartTagCloseAngleIndex = markupElementSyntax.StartTag.CloseAngle.SpanStart,
+            EndTagCloseAngleIndex = markupElementSyntax.EndTag.CloseAngle.EndPosition,
+        };
+
+        var resolutionParams = new RazorCodeActionResolutionParams()
+        {
+            TextDocument = context.Request.TextDocument,
+            Action = LanguageServerConstants.CodeActions.SimplifyTagToSelfClosingAction,
+            Language = RazorLanguageKind.Razor,
+            DelegatedDocumentUri = context.DelegatedDocumentUri,
+            Data = actionParams,
+        };
+
+        var codeAction = RazorCodeActionFactory.CreateSimplifyTagToSelfClosing(resolutionParams);
+        return Task.FromResult<ImmutableArray<RazorVSInternalCodeAction>>([codeAction]);
+    }
+
+    internal static bool IsApplicableTo(MarkupTagHelperElementSyntax markupElementSyntax)
+    {
+        // If there is no end tag, then the element is either already self-closing, or invalid. Either way, don't offer.
+        if (markupElementSyntax.EndTag is null)
+        {
+            return false;
+        }
+
+        if (markupElementSyntax is not { TagHelperInfo.BindingResult.Descriptors: [.. var descriptors] })
+        {
+            return false;
+        }
+
+        // Check whether the element has any non-whitespace content
+        if (markupElementSyntax is { Body: { } body } && body.Any(static n => !n.ContainsOnlyWhitespace()))
+        {
+            return false;
+        }
+
+        // Get symbols for the markup element
+        var boundTagHelper = descriptors.FirstOrDefault(static d => d.IsComponentTagHelper);
+        if (boundTagHelper == null)
+        {
+            return false;
+        }
+
+        // Check whether the Component must have children
+        foreach (var attribute in boundTagHelper.BoundAttributes)
+        {
+            // Parameter is not required
+            if (attribute is { IsEditorRequired: false })
+            {
+                continue;
+            }
+
+            // Parameter is not a `RenderFragment` or `RenderFragment<T>`
+            if (!attribute.IsChildContentProperty())
+            {
+                continue;
+            }
+
+            // Parameter is not set or bound as an attribute
+            if (!markupElementSyntax.TagHelperInfo!.BindingResult.Attributes.Any(a =>
+                RazorSyntaxFacts.TryGetComponentParameterNameFromFullAttributeName(a.Key, out var componentParameterName, out var directiveAttributeParameter) &&
+                componentParameterName.SequenceEqual(attribute.Name) &&
+                directiveAttributeParameter is { IsEmpty: true } or "get"
+            ))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/SimplifyTagToSelfClosingCodeActionResolver.cs

@@ -0,0 +1,57 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Text.Json;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Razor.CodeActions.Models;
+using Microsoft.CodeAnalysis.Razor.Formatting;
+using Microsoft.CodeAnalysis.Razor.ProjectSystem;
+using Microsoft.CodeAnalysis.Razor.Protocol;
+
+namespace Microsoft.CodeAnalysis.Razor.CodeActions.Razor;
+
+internal class SimplifyTagToSelfClosingCodeActionResolver : IRazorCodeActionResolver
+{
+    public string Action => LanguageServerConstants.CodeActions.SimplifyTagToSelfClosingAction;
+
+    public async Task<WorkspaceEdit?> ResolveAsync(DocumentContext documentContext, JsonElement data, RazorFormattingOptions options, CancellationToken cancellationToken)
+    {
+        if (data.ValueKind == JsonValueKind.Undefined)
+        {
+            return null;
+        }
+
+        var actionParams = JsonSerializer.Deserialize<SimplifyTagToSelfClosingCodeActionParams>(data.GetRawText());
+        if (actionParams is null)
+        {
+            return null;
+        }
+
+        var componentDocument = await documentContext.GetCodeDocumentAsync(cancellationToken).ConfigureAwait(false);
+
+        var text = componentDocument.Source.Text;
+        var removeRange = text.GetRange(actionParams.StartTagCloseAngleIndex, actionParams.EndTagCloseAngleIndex);
+
+        var documentChanges = new TextDocumentEdit[]
+        {
+            new TextDocumentEdit
+            {
+                TextDocument = new OptionalVersionedTextDocumentIdentifier { DocumentUri= new(documentContext.Uri) },
+                Edits =
+                [
+                    new TextEdit
+                    {
+                        NewText = " />",
+                        Range = removeRange,
+                    }
+                ],
+            }
+        };
+
+        return new WorkspaceEdit
+        {
+            DocumentChanges = documentChanges,
+        };
+    }
+}

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Completion/DirectiveAttributeEventParameterCompletionItemProvider.cs

@@ -1,5 +1,5 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the MIT license. See License.txt in the project root for license information.
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
 using System.Collections.Immutable;

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/Protocol/LanguageServerConstants.cs

@@ -43,6 +43,8 @@ public static class CodeActions
 
         public const string ExtractToNewComponentAction = "ExtractToNewComponent";
 
+        public const string SimplifyTagToSelfClosingAction = "SimplifyTagToSelfClosing";
+
         public const string CreateComponentFromTag = "CreateComponentFromTag";
 
         public const string AddUsing = "AddUsing";

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/RazorSyntaxFacts.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language;
@@ -116,6 +117,43 @@ static TextSpan CalculateFullSpan(MarkupTextLiteralSyntax attributeName, MarkupT
         }
     }
 
+    /// <summary>
+    /// For example given "&lt;Goo @bi$$nd-Value:after="val" /&gt;", it would return the span from "V" to "e".
+    /// </summary>
+    public static bool TryGetComponentParameterNameFromFullAttributeName(string fullAttributeName, out ReadOnlySpan<char> componentParameterName, out ReadOnlySpan<char> directiveAttributeParameter)
+    {
+        componentParameterName = fullAttributeName.AsSpan();
+        directiveAttributeParameter = default;
+        if (componentParameterName.IsEmpty)
+        {
+            return false;
+        }
+
+        // Parse @bind directive
+        if (componentParameterName[0] == '@')
+        {
+            // Trim `@` transition
+            componentParameterName = componentParameterName[1..];
+
+            // Check for and trim `bind-` directive prefix
+            if (!componentParameterName.StartsWith("bind-", StringComparison.Ordinal))
+            {
+                return false;
+            }
+
+            componentParameterName = componentParameterName["bind-".Length..];
+
+            // Trim directive parameter name, if any
+            if (componentParameterName.LastIndexOf(':') is int colonIndex and > 0)
+            {
+                directiveAttributeParameter = componentParameterName[(colonIndex + 1)..];
+                componentParameterName = componentParameterName[..colonIndex];
+            }
+        }
+
+        return true;
+    }
+
     public static CSharpCodeBlockSyntax? TryGetCSharpCodeFromCodeBlock(RazorSyntaxNode node)
     {
         if (node is CSharpCodeBlockSyntax block &&