Handle InlayHint filtering clientside and allow the user to choose InlayHints (#68)

* Add `InlayHintProvider` class to request and filter InlayHints clientside

!! This causes duplicates with the old InlayHint implementation

* Override `LanguageClient` to disable the automatic duplicate InlayHints

* Add a whitespace to restore layout and include markdown in the settings description

* Rework the Doc comment and enhance the markdown preview

* Apply Padding by parsing the response with `padLeft?` and `padRight?` fields

* Change `padRight` to `paddingRight` and remove not implemented left padding

* Add left padding according to LSP spec and add a README mention

* Register the `InlayHintsProvider` for literate effekt

* rename to `inlayHintsProvider` to match conventions

* WIP

* Rework the InlayHintsProvider by using converters

* Send a strongly typed LSP req instead of a raw Sting

* Clean up the inlay hints provider

* Fix whitespace and remove comments

Author: JakubSchwenkbeck

README.md

@@ -22,6 +22,7 @@ With this setup the extension should start the server when an Effekt file is ope
 This extension supports inlay hints that can display useful information about Effekt programs that is not explicitly written out in the source code.
 For example, this includes showing inferred types and [Effekt captures](https://effekt-lang.org/tour/captures).
 You can enable inlay hints in the [VSCode settings](vscode://settings/editor.inlayHints.enabled) at `Editor › Inlay Hints: Enabled`.
+Currently you can choose if you want to display the capture inlay hints at `Effekt › Inlay Hints: Captures`.
 
 ## License
 

package.json

@@ -148,6 +148,11 @@
                     "type": "boolean",
                     "default": false,
                     "markdownDescription": "Connect to a running LSP server in debug mode. This setting is only for development of the VSCode plugin and the Effekt compiler.\n\n⚠️ **WARNING:** For this option to work, you first need to start `effekt --server --debug` as a separate process."
+                },
+                "effekt.inlayHints.captures": {
+                    "type": "boolean",
+                    "default": true,
+                    "markdownDescription": "Show capture inlay hints:\n\n ```effekt\n'{io}' def main(): Unit = { println(\" Hello Effekt! \") }\n```"
                 }
             }
         },

src/extension.ts

@@ -10,10 +10,32 @@ import {
 } from 'vscode-languageclient/node';
 import { EffektManager } from './effektManager';
 import { EffektIRContentProvider } from './irProvider';
-
+import { InlayHintProvider } from './inlayHintsProvider';
 import * as net from 'net';
 
-let client: LanguageClient;
+/**
+ * Overrides the `registerFeature` method to disable the built-in inlay hints feature.
+ *
+ * By default the LanguageClient provides inlay hints automatically, which does not allow 
+ * for filtering Inlay Hints based on their 'data'-field. We use the 'data'-field to allow
+ * the user to select which inlay hints the extension should show.
+ * 
+ * By doing this, we retain full control over how inlay hints are displayed, allowing us to
+ * implement custom logic.
+ *
+ * Note: This approach relies on identifying the inlay hints feature by its constructor name
+ * (`InlayHintsFeature`). If the LSP implementation changes, this logic may need to be updated.
+ */
+class EffektLanguageClient extends LanguageClient {
+    public registerFeature(feature: any) {
+        if (feature.constructor.name === 'InlayHintsFeature') { 
+            return; 
+        }
+        super.registerFeature(feature);
+    }
+}
+
+let client: EffektLanguageClient;
 let effektManager: EffektManager;
 
 function registerCommands(context: vscode.ExtensionContext) {
@@ -160,7 +182,7 @@ export async function activate(context: vscode.ExtensionContext) {
         diagnosticCollectionName: "effekt"
     };
 
-    client = new LanguageClient(
+    client = new EffektLanguageClient(
         'effektLanguageServer',
         'Effekt Language Server',
         serverOptions,
@@ -258,6 +280,16 @@ export async function activate(context: vscode.ExtensionContext) {
 
     await client.start();
     context.subscriptions.push(client);
+
+    vscode.languages.registerInlayHintsProvider(
+        { scheme: 'file', language: 'effekt' },
+        new InlayHintProvider(client)
+    );
+
+    vscode.languages.registerInlayHintsProvider(
+        { scheme: 'file', language: 'literate effekt' },
+        new InlayHintProvider(client)
+    );
 }
 
 export function deactivate(): Thenable<void> | undefined {

src/inlayHintsProvider.ts

@@ -0,0 +1,56 @@
+import * as vscode from 'vscode';
+import { Code2ProtocolConverter, LanguageClient, Protocol2CodeConverter } from 'vscode-languageclient/node';
+import {
+  InlayHintRequest,
+  InlayHintParams,
+  InlayHint as LspInlayHint
+} from 'vscode-languageserver-protocol';
+
+export class InlayHintProvider implements vscode.InlayHintsProvider {
+  private client: LanguageClient;
+  private protocol2code: Protocol2CodeConverter;
+  private code2protocol : Code2ProtocolConverter;
+
+  constructor(client: LanguageClient) {
+    this.client = client;
+    this.protocol2code = client.protocol2CodeConverter;
+    this.code2protocol = client.code2ProtocolConverter;
+  }
+
+  async provideInlayHints(
+    document: vscode.TextDocument,
+    range: vscode.Range,
+    _token: vscode.CancellationToken
+  ): Promise<vscode.InlayHint[]> {
+    const config = vscode.workspace.getConfiguration('effekt');
+    const showCaptureHints = config.get<boolean>('inlayHints.captures', true);
+
+    const editorHintsEnabled = vscode.workspace
+      .getConfiguration('editor.inlayHints')
+      .get<string>('enabled', 'on');
+    if (editorHintsEnabled === 'off') {
+      return [];
+    }
+
+    const params: InlayHintParams = {
+      textDocument: this.code2protocol.asTextDocumentIdentifier(document),
+      range: this.code2protocol.asRange(range)
+    };
+
+    const response = (await this.client.sendRequest(
+      InlayHintRequest.type,
+      params
+    )) as LspInlayHint[] | null | undefined;
+
+    if (!response) {
+      return [];
+    }
+
+    const filtered = response.filter(h => {
+      return !(h.data === 'capture' && !showCaptureHints);
+    });
+
+    const hints = await this.protocol2code.asInlayHints(filtered, _token);
+    return hints || [];
+  }
+}