Better handle parameter attribute directive completion (#12473)

Modifies completion in several ways:

Makes ':' no longer a commit character. This being a commit character was causing difficulties as it and '=' require fundamentally different completion commit behavior, and LSP doesn't support that for a single completion item.
Makes parameter completions show up in attribute name contexts too. This is nice for discoverability.

Fixes: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2607948

Author: ToddGrun

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

@@ -89,7 +89,6 @@ public static void AddCompletionServices(this IServiceCollection services)
         services.AddSingleton<IRazorCompletionFactsService, LspRazorCompletionFactsService>();
         services.AddSingleton<IRazorCompletionItemProvider, DirectiveCompletionItemProvider>();
         services.AddSingleton<IRazorCompletionItemProvider, DirectiveAttributeCompletionItemProvider>();
-        services.AddSingleton<IRazorCompletionItemProvider, DirectiveAttributeParameterCompletionItemProvider>();
         services.AddSingleton<IRazorCompletionItemProvider, DirectiveAttributeEventParameterCompletionItemProvider>();
         services.AddSingleton<IRazorCompletionItemProvider, DirectiveAttributeTransitionCompletionItemProvider>();
         services.AddSingleton<IRazorCompletionItemProvider, MarkupTransitionCompletionItemProvider>();

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

@@ -0,0 +1,17 @@
+// 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.Immutable;
+
+namespace Microsoft.CodeAnalysis.Razor.Completion;
+
+internal record DirectiveAttributeCompletionContext
+{
+    public required string SelectedAttributeName { get; init; }
+    public string? SelectedParameterName { get; init; }
+    public ImmutableArray<string> ExistingAttributes { get; init => field = value.NullToEmpty(); } = [];
+    public bool UseSnippets { get; init; } = true;
+    public bool InAttributeName { get; init; } = true;
+    public bool InParameterName { get; init; }
+    public RazorCompletionOptions Options { get; init; }
+}

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

@@ -74,8 +74,10 @@ public static RazorCompletionItem CreateDirectiveAttribute(
 
     public static RazorCompletionItem CreateDirectiveAttributeParameter(
         string displayText, string insertText,
-        AggregateBoundAttributeDescription descriptionInfo)
-        => new(RazorCompletionItemKind.DirectiveAttributeParameter, displayText, insertText, sortText: null, descriptionInfo, commitCharacters: [], isSnippet: false);
+        AggregateBoundAttributeDescription descriptionInfo,
+        ImmutableArray<RazorCommitCharacter> commitCharacters,
+        bool isSnippet)
+        => new(RazorCompletionItemKind.DirectiveAttributeParameter, displayText, insertText, sortText: null, descriptionInfo, commitCharacters, isSnippet);
 
     public static RazorCompletionItem CreateMarkupTransition(
         string displayText, string insertText,

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

@@ -13,9 +13,6 @@ internal sealed class OOPDirectiveCompletionItemProvider : DirectiveCompletionIt
 [Export(typeof(IRazorCompletionItemProvider)), Shared]
 internal sealed class OOPDirectiveAttributeCompletionItemProvider : DirectiveAttributeCompletionItemProvider;
 
-[Export(typeof(IRazorCompletionItemProvider)), Shared]
-internal sealed class OOPDirectiveAttributeParameterCompletionItemProvider : DirectiveAttributeParameterCompletionItemProvider;
-
 [Export(typeof(IRazorCompletionItemProvider)), Shared]
 internal sealed class OOPDirectiveAttributeEventParameterCompletionItemProvider : DirectiveAttributeEventParameterCompletionItemProvider;
 

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

@@ -13,7 +13,6 @@ internal sealed class LegacyRazorCompletionFactsService : AbstractRazorCompletio
     private static readonly ImmutableArray<IRazorCompletionItemProvider> s_providers =
     [
         new DirectiveAttributeCompletionItemProvider(),
-        new DirectiveAttributeParameterCompletionItemProvider(),
         new DirectiveCompletionItemProvider()
     ];
 

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/Completion/OOPRazorCompletionItemProviders.cs

@@ -145,7 +145,9 @@ public async Task ResolveAsync_DirectiveAttributeParameterCompletion_ReturnsComp
         var razorCompletionItem = RazorCompletionItem.CreateDirectiveAttributeParameter(
             displayText: "TestItem",
             insertText: "TestItem",
-            _attributeDescription);
+            _attributeDescription,
+            commitCharacters: [],
+            isSnippet: false);
         var completionList = CreateLSPCompletionList(razorCompletionItem);
         var completionItem = (VSInternalCompletionItem)completionList.Items.Single();
 
@@ -235,7 +237,9 @@ public async Task ResolveAsync_VS_DirectiveAttributeParameterCompletion_ReturnsC
         var razorCompletionItem = RazorCompletionItem.CreateDirectiveAttributeParameter(
             displayText: "TestItem",
             insertText: "TestItem",
-            _attributeDescription);
+            _attributeDescription,
+            commitCharacters: [],
+            isSnippet: false);
         var completionList = CreateLSPCompletionList(razorCompletionItem);
         var completionItem = (VSInternalCompletionItem)completionList.Items.Single();