Add the 'Go to Definition' feature in the Elm language server and VSCode

implement/CHANGELOG.md

@@ -47,3 +47,7 @@ Published the first version of the Elm developer tools VSCode extension, with a
 + Added feature: Completions: Shows completion suggestions matching the current context
 + Added feature: Hover tips: Shows type annotations and documentation for a type alias, module, custom type or function
 
+## 2024-12-15 - Expanded VSCode Extension and Language Server
+
++ Added feature: 'Go to Definition'
+

implement/Pine.Core/LanguageServerProtocol/LocationLink.cs

@@ -0,0 +1,10 @@
+namespace Pine.Core.LanguageServerProtocol;
+
+/// <summary>
+/// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#locationLink
+/// </summary>
+public record LocationLink(
+    Range? OriginSelectionRange,
+    string TargetUri,
+    Range TargetRange,
+    Range TargetSelectionRange);

implement/Pine.Core/LanguageServerProtocol/ServerCapabilities.cs

@@ -10,7 +10,10 @@ public record ServerCapabilities(
     TextDocumentSyncOptions? TextDocumentSync = null,
     ServerCapabilitiesWorkspace? Workspace = null,
     bool? HoverProvider = null,
-    CompletionOptions? CompletionProvider = null);
+    CompletionOptions? CompletionProvider = null,
+    bool? DeclarationProvider = null,
+    bool? DefinitionProvider = null,
+    bool? TypeDefinitionProvider = null);
 
 /// <summary>
 /// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocumentSyncKind

implement/Pine.Core/Pine.Core.csproj

@@ -3,14 +3,14 @@
   <PropertyGroup>
     <TargetFramework>net8.0</TargetFramework>
     <Nullable>enable</Nullable>
-    <AssemblyVersion>0.3.27</AssemblyVersion>
-    <FileVersion>0.3.27</FileVersion>
+    <AssemblyVersion>0.3.28</AssemblyVersion>
+    <FileVersion>0.3.28</FileVersion>
     <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
   </PropertyGroup>
 
   <PropertyGroup>
     <PackageId>Pine.Core</PackageId>
-    <Version>0.3.27</Version>
+    <Version>0.3.28</Version>
     <Description>The cross-platform Elm runtime environment</Description>
     <PackageTags>Functional;Elm;Runtime;Compiler;VM;DBMS</PackageTags>
     <RepositoryUrl>https://github.com/pine-vm/pine.git</RepositoryUrl>

implement/pine/Elm/LanguageServer.cs

@@ -113,6 +113,8 @@ private void Log(string message)
                     AllCommitCharacters: null,
                     ResolveProvider: null),
 
+                DefinitionProvider = true,
+
                 Workspace = new ServerCapabilitiesWorkspace
                 {
                     WorkspaceFolders = new WorkspaceFoldersServerCapabilities(Supported: true, ChangeNotifications: true),
@@ -319,6 +321,8 @@ public void TextDocument_didChange(
     {
         var textDocumentUri = System.Uri.UnescapeDataString(textDocument.Uri);
 
+        allSeenDocumentUris[textDocumentUri] = textDocumentUri;
+
         Log(
             "TextDocument_didChange: " + textDocumentUri +
             " (" + contentChanges.Count + " content changes)");
@@ -694,6 +698,116 @@ public CompletionItem[] TextDocument_completion(
             ];
     }
 
+    public IReadOnlyList<Location> TextDocument_definition(
+        TextDocumentPositionParams positionParams)
+    {
+        var textDocumentUri = System.Uri.UnescapeDataString(positionParams.TextDocument.Uri);
+
+        var clock = System.Diagnostics.Stopwatch.StartNew();
+
+        Log("TextDocument_definition: " + textDocumentUri + " at " + positionParams.Position);
+
+        var localPathResult = DocumentUriAsLocalPath(textDocumentUri);
+        {
+            if (localPathResult.IsErrOrNull() is { } err)
+            {
+                Log("Ignoring URI: " + err + ": " + textDocumentUri);
+                return [];
+            }
+        }
+
+        if (localPathResult.IsOkOrNull() is not { } localPath)
+        {
+            throw new System.NotImplementedException(
+                "Unexpected result type: " + localPathResult.GetType());
+        }
+
+        var filePathOpenedInEditor = PathItemsFromFlatPath(localPath);
+
+        var provideDefinitionResult =
+            ProvideDefinition(
+                new Interface.ProvideHoverRequestStruct(
+                    filePathOpenedInEditor,
+                    PositionLineNumber: (int)positionParams.Position.Line + 1,
+                    PositionColumn: (int)positionParams.Position.Character + 1));
+
+        {
+            if (provideDefinitionResult.IsErrOrNull() is { } err)
+            {
+                Log("Failed to provide definition: " + err);
+                return [];
+            }
+        }
+
+        if (provideDefinitionResult.IsOkOrNull() is not { } provideDefinitionOk)
+        {
+            throw new System.NotImplementedException(
+                "Unexpected result type: " + provideDefinitionResult.GetType());
+        }
+
+        Log(
+            "Completed provide definition in " +
+            CommandLineInterface.FormatIntegerForDisplay(clock.ElapsedMilliseconds) + " ms, returning " +
+            provideDefinitionOk.Count + " items");
+
+
+        string? correspondingUri(IReadOnlyList<string> path)
+        {
+            var flatPathForward = string.Join('/', path);
+            var flatPathBackward = string.Join('\\', path);
+
+            var fromSeenUris =
+                allSeenDocumentUris
+                .FirstOrDefault(uri =>
+                DocumentUriAsLocalPath(uri.Value).IsOkOrNull() is { } asLocalOk &&
+                (asLocalOk == flatPathBackward ||
+                asLocalOk == flatPathBackward)).Key;
+
+            if (fromSeenUris is not null)
+                return fromSeenUris;
+
+            return
+                System.Uri.TryCreate(flatPathForward, System.UriKind.Absolute, out var uri)
+                ?
+                uri.AbsoluteUri
+                :
+                null;
+        }
+
+        var locations =
+            provideDefinitionOk
+            .SelectMany(location =>
+            {
+                if (correspondingUri(location.FilePath) is not { } uri)
+                {
+                    Log("No corresponding URI for " + string.Join('/', location.FilePath));
+
+                    return (IReadOnlyList<Location>)[];
+                }
+
+                return
+                    [new Location(
+                        uri,
+                        new Range(
+                            Start: new Position(
+                                Line: (uint)location.Range.StartLineNumber - 1,
+                                Character: (uint)location.Range.StartColumn - 1),
+                            End: new Position(
+                                Line: (uint)location.Range.EndLineNumber - 1,
+                                Character: (uint)location.Range.EndColumn - 1)))];
+            })
+            .ToImmutableArray();
+
+        Log(
+            "Returning " + locations.Length + " locations: " +
+            string.Join(
+                ", ",
+                locations
+                .Select(l => l.Uri + ": " + l.Range.Start.Line)));
+
+        return locations;
+    }
+
     public void TextDocument_didSave(
         DidSaveTextDocumentParams didSaveParams,
         System.Action<TextDocumentIdentifier, IReadOnlyList<Diagnostic>> publishDiagnostics)
@@ -1049,6 +1163,36 @@ public Result<string, IReadOnlyList<string>> ProvideHover(
             provideCompletionItemsResponse.CompletionItems);
     }
 
+    public Result<string, IReadOnlyList<Interface.LocationUnderFilePath>>
+        ProvideDefinition(
+            Interface.ProvideHoverRequestStruct provideDefinitionRequest)
+    {
+        var genericRequestResult =
+            HandleRequest(
+                new Interface.Request.ProvideDefinitionRequest(provideDefinitionRequest));
+
+        if (genericRequestResult.IsErrOrNull() is { } err)
+        {
+            return err;
+        }
+
+        if (genericRequestResult.IsOkOrNull() is not { } requestOk)
+        {
+            throw new System.NotImplementedException(
+                "Unexpected request result type: " + genericRequestResult.GetType());
+        }
+
+        if (requestOk is not Interface.Response.ProvideDefinitionResponse provideDefinitionResponse)
+        {
+            throw new System.NotImplementedException(
+                "Unexpected request result type: " + requestOk.GetType());
+        }
+
+        return
+            Result<string, IReadOnlyList<Interface.LocationUnderFilePath>>.ok(
+                provideDefinitionResponse.Locations);
+    }
+
     public Result<string, Interface.Response> HandleRequest(
         Interface.Request request)
     {

implement/pine/Elm/LanguageServerRpcTarget.cs

@@ -137,6 +137,16 @@ public CompletionItem[] TextDocument_completion(
         return Server.TextDocument_completion(positionParams);
     }
 
+    /// <summary>
+    /// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_definition
+    /// </summary>
+    [JsonRpcMethod("textDocument/definition", UseSingleObjectParameterDeserialization = true)]
+    public IReadOnlyList<Location> TextDocument_definition(
+        TextDocumentPositionParams positionParams)
+    {
+        return Server.TextDocument_definition(positionParams);
+    }
+
 
     /// <summary>
     /// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_didSave

implement/pine/Elm/LanguageServiceInterface/LanguageServiceRequest.cs

@@ -40,6 +40,9 @@ public record ProvideHoverRequest(ProvideHoverRequestStruct Request)
 
     public record ProvideCompletionItemsRequest(ProvideCompletionItemsRequestStruct Request)
         : Request;
+
+    public record ProvideDefinitionRequest(ProvideHoverRequestStruct Request)
+        : Request;
 }
 
 public record ProvideHoverRequestStruct(
@@ -116,6 +119,13 @@ addFileRequest.Blob.AsText is { } asText
                         Encode(provideCompletionItemsRequest.Request)
                     ]),
 
+            Request.ProvideDefinitionRequest provideDefinitionRequest =>
+                ElmValueEncoding.TagAsPineValue(
+                    "ProvideDefinitionRequest",
+                    [
+                        Encode(provideDefinitionRequest.Request)
+                    ]),
+
             _ =>
             throw new System.NotImplementedException(
                 "Unexpected request type: " + request.GetType())