Allow LSP and cohosting to provide specialized methods to get a syntax tree for a C# document

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Definition/RazorComponentDefinitionService.cs

@@ -5,10 +5,15 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor.Language;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Razor.DocumentMapping;
 using Microsoft.CodeAnalysis.Razor.GoToDefinition;
 using Microsoft.CodeAnalysis.Razor.Logging;
+using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Razor.Workspaces;
 
 namespace Microsoft.AspNetCore.Razor.LanguageServer.Definition;
@@ -19,4 +24,9 @@ internal sealed class RazorComponentDefinitionService(
     ILoggerFactory loggerFactory)
     : AbstractRazorComponentDefinitionService(componentSearchEngine, documentMappingService, loggerFactory.GetOrCreateLogger<RazorComponentDefinitionService>())
 {
+    protected override ValueTask<SyntaxTree> GetCSharpSyntaxTreeAsync(IDocumentSnapshot documentSnapshot, RazorCodeDocument codeDocument, CancellationToken cancellationToken)
+    {
+        var csharpText = codeDocument.GetCSharpSourceText();
+        return new(CSharpSyntaxTree.ParseText(csharpText, cancellationToken: cancellationToken));
+    }
 }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/GoToDefinition/AbstractRazorComponentDefinitionService.cs

@@ -70,9 +70,10 @@ internal abstract class AbstractRazorComponentDefinitionService(
             _logger.LogInformation($"Attempting to get definition from an attribute directly.");
 
             var originCodeDocument = await documentSnapshot.GetGeneratedOutputAsync().ConfigureAwait(false);
+            var syntaxTree = await GetCSharpSyntaxTreeAsync(documentSnapshot, originCodeDocument, cancellationToken).ConfigureAwait(false);
 
             var range = await RazorComponentDefinitionHelpers
-                .TryGetPropertyRangeAsync(originCodeDocument, attributeDescriptor.GetPropertyName(), _documentMappingService, _logger, cancellationToken)
+                .TryGetPropertyRangeAsync(originCodeDocument, syntaxTree, attributeDescriptor.GetPropertyName(), _documentMappingService, _logger, cancellationToken)
                 .ConfigureAwait(false);
 
             if (range is not null)
@@ -87,4 +88,6 @@ internal abstract class AbstractRazorComponentDefinitionService(
         // at least then press F7 to go there.
         return VsLspFactory.DefaultRange;
     }
+
+    protected abstract ValueTask<SyntaxTree> GetCSharpSyntaxTreeAsync(IDocumentSnapshot documentSnapshot, RazorCodeDocument codeDocument, CancellationToken cancellationToken);
 }

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/GoToDefinition/RazorComponentDefinitionHelpers.cs

@@ -8,7 +8,6 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Syntax;
-using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Razor.DocumentMapping;
 using Microsoft.CodeAnalysis.Razor.Logging;
@@ -131,12 +130,13 @@ internal static class RazorComponentDefinitionHelpers
 
     public static async Task<LspRange?> TryGetPropertyRangeAsync(
         RazorCodeDocument codeDocument,
+        SyntaxTree csharpSyntaxTree,
         string propertyName,
         IDocumentMappingService documentMappingService,
         ILogger logger,
         CancellationToken cancellationToken)
     {
-        // Parse the C# file and find the property that matches the name.
+        // Process the C# tree and find the property that matches the name.
         // We don't worry about parameter attributes here for two main reasons:
         //   1. We don't have symbolic information, so the best we could do would be checking for any
         //      attribute named Parameter, regardless of which namespace. It also means we would have
@@ -147,9 +147,8 @@ internal static class RazorComponentDefinitionHelpers
         //      tag helper attribute. If they don't have the [Parameter] attribute then the Razor compiler
         //      will error, but allowing them to Go To Def on that property regardless, actually helps
         //      them fix the error.
-        var csharpText = codeDocument.GetCSharpSourceText();
-        var syntaxTree = CSharpSyntaxTree.ParseText(csharpText, cancellationToken: cancellationToken);
-        var root = await syntaxTree.GetRootAsync(cancellationToken).ConfigureAwait(false);
+
+        var root = await csharpSyntaxTree.GetRootAsync(cancellationToken).ConfigureAwait(false);
 
         // Since we know how the compiler generates the C# source we can be a little specific here, and avoid
         // long tree walks. If the compiler ever changes how they generate their code, the tests for this will break
@@ -169,6 +168,7 @@ internal static class RazorComponentDefinitionHelpers
                 return null;
             }
 
+            var csharpText = codeDocument.GetCSharpSourceText();
             var range = csharpText.GetRange(property.Identifier.Span);
             if (documentMappingService.TryMapToHostDocumentRange(codeDocument.GetCSharpDocument(), range, out var originalRange))
             {

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/GoToDefinition/RazorComponentDefinitionService.cs

@@ -2,10 +2,17 @@
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
 using System.Composition;
+using System.Diagnostics;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor;
+using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.CodeAnalysis.Razor.DocumentMapping;
 using Microsoft.CodeAnalysis.Razor.GoToDefinition;
 using Microsoft.CodeAnalysis.Razor.Logging;
+using Microsoft.CodeAnalysis.Razor.ProjectSystem;
 using Microsoft.CodeAnalysis.Razor.Workspaces;
+using Microsoft.CodeAnalysis.Remote.Razor.ProjectSystem;
 
 namespace Microsoft.CodeAnalysis.Remote.Razor.GoToDefinition;
 
@@ -14,7 +21,25 @@ namespace Microsoft.CodeAnalysis.Remote.Razor.GoToDefinition;
 internal sealed class RazorComponentDefinitionService(
     IRazorComponentSearchEngine componentSearchEngine,
     IDocumentMappingService documentMappingService,
+    IFilePathService filePathService,
     ILoggerFactory loggerFactory)
     : AbstractRazorComponentDefinitionService(componentSearchEngine, documentMappingService, loggerFactory.GetOrCreateLogger<RazorComponentDefinitionService>())
 {
+    private readonly IFilePathService _filePathService = filePathService;
+
+    protected override async ValueTask<SyntaxTree> GetCSharpSyntaxTreeAsync(IDocumentSnapshot documentSnapshot, RazorCodeDocument codeDocument, CancellationToken cancellationToken)
+    {
+        Debug.Assert(documentSnapshot is RemoteDocumentSnapshot, "This method only works on document snapshots created in the OOP process");
+
+        var remoteSnapshot = (RemoteDocumentSnapshot)documentSnapshot;
+        var document = await remoteSnapshot.GetGeneratedDocumentAsync(_filePathService).ConfigureAwait(false);
+
+        if (document.TryGetSyntaxTree(out var syntaxTree))
+        {
+            return syntaxTree;
+        }
+
+        var tree = await document.GetSyntaxTreeAsync(cancellationToken).ConfigureAwait(false);
+        return tree.AssumeNotNull();
+    }
 }

src/Razor/test/Microsoft.AspNetCore.Razor.LanguageServer.Test/Definition/RazorComponentDefinitionHelpersTest.cs

@@ -1,11 +1,13 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT license. See License.txt in the project root for license information.
 
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.LanguageServer.Completion;
 using Microsoft.AspNetCore.Razor.Test.Common;
 using Microsoft.AspNetCore.Razor.Test.Common.LanguageServer;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Razor.GoToDefinition;
 using Microsoft.CodeAnalysis.Testing;
 using Microsoft.VisualStudio.LanguageServer.Protocol;
@@ -392,7 +394,10 @@ public class RazorComponentDefinitionHelpersTest(ITestOutputHelper testOutput) :
 
         var documentMappingService = new LspDocumentMappingService(FilePathService, new TestDocumentContextFactory(), LoggerFactory);
 
-        var range = await RazorComponentDefinitionHelpers.TryGetPropertyRangeAsync(codeDocument, propertyName, documentMappingService, Logger, DisposalToken);
+        var csharpText = codeDocument.GetCSharpSourceText();
+        var syntaxTree = CSharpSyntaxTree.ParseText(csharpText);
+
+        var range = await RazorComponentDefinitionHelpers.TryGetPropertyRangeAsync(codeDocument, syntaxTree, propertyName, documentMappingService, Logger, DisposalToken);
         Assert.NotNull(range);
         Assert.Equal(expectedRange, range);
     }