Support inlay hints for parameter names

package.json

@@ -23,7 +23,7 @@
     "virtualWorkspaces": false
   },
   "engines": {
-    "vscode": "^1.61.0"
+    "vscode": "^1.65.0"
   },
   "repository": {
     "type": "git",
@@ -857,6 +857,22 @@
           "default": "line",
           "description": "Show quickfixes at the problem or line level.",
           "scope": "window"
+        },
+        "java.inlayHints.parameterNames.enabled": {
+          "type": "string",
+          "enum": [
+            "none",
+            "literals",
+            "all"
+          ],
+          "enumDescriptions": [
+            "Disable parameter name hints",
+            "Enable parameter name hints only for literal arguments",
+            "Enable parameter name hints for literal and non-literal arguments"
+          ],
+          "default": "literals",
+          "markdownDescription": "Enable/disable inlay hints for parameter names:\n```java\n\nInteger.valueOf(/* s: */ '123', /* radix: */ 10)\n \n```\n",
+          "scope": "window"
         }
       }
     },
@@ -1141,7 +1157,7 @@
     "@types/mocha": "^5.2.5",
     "@types/node": "^8.10.51",
     "@types/semver": "^7.3.8",
-    "@types/vscode": "^1.53.0",
+    "@types/vscode": "^1.65.0",
     "@types/winreg": "^1.2.30",
     "@types/winston": "^2.4.4",
     "gulp": "^4.0.2",

src/extension.ts

@@ -4,7 +4,7 @@ import * as path from 'path';
 import * as os from 'os';
 import * as fs from 'fs';
 import * as fse from 'fs-extra';
-import { workspace, extensions, ExtensionContext, window, commands, ViewColumn, Uri, languages, IndentAction, InputBoxOptions, EventEmitter, OutputChannel, TextDocument, RelativePattern, ConfigurationTarget, WorkspaceConfiguration, env, UIKind, CodeActionContext, Diagnostic } from 'vscode';
+import { workspace, extensions, ExtensionContext, window, commands, ViewColumn, Uri, languages, IndentAction, InputBoxOptions, EventEmitter, OutputChannel, TextDocument, RelativePattern, ConfigurationTarget, WorkspaceConfiguration, env, UIKind, CodeActionContext, Diagnostic, CodeActionTriggerKind } from 'vscode';
 import { ExecuteCommandParams, ExecuteCommandRequest, LanguageClientOptions, RevealOutputChannelOn, ErrorHandler, Message, ErrorAction, CloseAction, DidChangeConfigurationNotification, CancellationToken, CodeActionRequest, CodeActionParams, Command } from 'vscode-languageclient';
 import { LanguageClient } from 'vscode-languageclient/node';
 import { collectJavaExtensions, isContributedPartUpdated } from './plugin';
@@ -134,6 +134,11 @@ export class OutputInfoCollector implements OutputChannel {
 		this.channel.appendLine(value);
 	}
 
+	replace(value: string): void {
+		this.clear();
+		this.append(value);
+	}
+
 	clear(): void {
 		this.channel.clear();
 	}
@@ -279,6 +284,7 @@ export function activate(context: ExtensionContext): Promise<ExtensionAPI> {
 								const codeActionContext: CodeActionContext = {
 									diagnostics: allDiagnostics,
 									only: context.only,
+									triggerKind: CodeActionTriggerKind.Invoke,
 								};
 								params.context = client.code2ProtocolConverter.asCodeActionContext(codeActionContext);
 							}

src/hoverAction.ts

@@ -75,10 +75,10 @@ class JavaHoverProvider implements HoverProvider {
 
         const contributed = new MarkdownString(contributedCommands.map((command) => this.convertCommandToMarkdown(command)).join(' | '));
         contributed.isTrusted = true;
-        let contents: MarkedString[] = [ contributed ];
+        let contents: MarkdownString[] = [ contributed ];
         let range;
         if (serverHover && serverHover.contents) {
-            contents = contents.concat(serverHover.contents);
+            contents = contents.concat(serverHover.contents as MarkdownString[]);
             range = serverHover.range;
         }
         return new Hover(contents, range);

src/inlayHintsProvider.ts

@@ -0,0 +1,95 @@
+import { CancellationToken, EventEmitter, InlayHint, InlayHintKind, InlayHintsProvider, Range, TextDocument } from "vscode";
+import * as ls from 'vscode-languageserver-protocol';
+import { LanguageClient, RequestType } from "vscode-languageclient/node";
+
+export class JavaInlayHintsProvider implements InlayHintsProvider {
+
+    private onDidChange = new EventEmitter<void>();
+    public onDidChangeInlayHints = this.onDidChange.event;
+
+    constructor(private client: LanguageClient) {
+        this.client.onRequest(InlayHintRefreshRequest.type, async () => {
+            this.onDidChange.fire();
+        });
+    }
+
+    public async provideInlayHints(document: TextDocument, range: Range, token: CancellationToken): Promise<InlayHint[]> {
+        const requestParams: InlayHintParams = {
+            textDocument: this.client.code2ProtocolConverter.asTextDocumentIdentifier(document),
+            range: this.client.code2ProtocolConverter.asRange(range)
+        };
+        try {
+            const values = await this.client.sendRequest(InlayHintRequest.type, requestParams, token);
+            if (token.isCancellationRequested) {
+                return [];
+            }
+            return asInlayHints(values, this.client);
+        } catch (error) {
+            return this.client.handleFailedRequest(InlayHintRequest.type, token, error, []);
+        }
+    }
+}
+
+/**
+ * A parameter literal used in inlay hints requests.
+ *
+ * @since 3.17.0 - proposed state
+ */
+ export type InlayHintParams = /*WorkDoneProgressParams &*/ {
+    /**
+     * The text document.
+     */
+    textDocument: ls.TextDocumentIdentifier;
+
+    /**
+     * The document range for which inlay hints should be computed.
+     */
+    range: ls.Range;
+};
+
+/**
+ * Inlay hint information.
+ *
+ * @since 3.17.0 - proposed state
+ */
+export type LSInlayHint = {
+
+    /**
+     * The position of this hint.
+     */
+    position: ls.Position;
+
+    /**
+     * The label of this hint. A human readable string or an array of
+     * InlayHintLabelPart label parts.
+     *
+     * *Note* that neither the string nor the label part can be empty.
+     */
+    label: string; // label: string | InlayHintLabelPart[];
+};
+
+namespace InlayHintRequest {
+    export const type: RequestType<InlayHintParams, LSInlayHint[], any> = new RequestType('textDocument/inlayHint');
+}
+
+/**
+ * @since 3.17.0 - proposed state
+ */
+namespace InlayHintRefreshRequest {
+    export const type: RequestType<void, void, void> = new RequestType('workspace/inlayHint/refresh');
+}
+
+async function asInlayHints(values: LSInlayHint[] | undefined | null, client: LanguageClient, ): Promise<InlayHint[] | undefined> {
+    if (!Array.isArray(values)) {
+        return undefined;
+    }
+    return values.map(lsHint => asInlayHint(lsHint, client));
+}
+
+function asInlayHint(value: LSInlayHint, client: LanguageClient): InlayHint {
+    const label = value.label;
+    const result = new InlayHint(client.protocol2CodeConverter.asPosition(value.position), label);
+    result.paddingRight = true;
+    result.kind = InlayHintKind.Parameter;
+    return result;
+}

src/standardLanguageClient.ts

@@ -34,6 +34,7 @@ import { buildFilePatterns } from './plugin';
 import { pomCodeActionMetadata, PomCodeActionProvider } from "./pom/pomCodeActionProvider";
 import { findRuntimes, IJavaRuntime } from "jdk-utils";
 import { snippetCompletionProvider } from "./snippetCompletionProvider";
+import { JavaInlayHintsProvider } from "./inlayHintsProvider";
 
 const extensionName = 'Language Support for Java';
 const GRADLE_CHECKSUM = "gradle/checksum/prompt";
@@ -501,6 +502,14 @@ export class StandardLanguageClient {
 				scheme: "file",
 				pattern: "**/pom.xml"
 			}, new PomCodeActionProvider(context), pomCodeActionMetadata);
+
+			if (languages.registerInlayHintsProvider) {
+				context.subscriptions.push(languages.registerInlayHintsProvider([
+					{ scheme: "file", language: "java", pattern: "**/*.java" },
+					{ scheme: "jdt", language: "java", pattern: "**/*.class" },
+					{ scheme: "untitled", language: "java", pattern: "**/*.java" }
+				], new JavaInlayHintsProvider(this.languageClient)));
+			}
 		});
 	}