First commit.

Signed-off-by: Chen Xiao <abigwc@gmail.com>

client/node_modules/langium/lib/lsp/signature-help-provider.d.ts

@@ -0,0 +1,39 @@
+/******************************************************************************
+ * Copyright 2022 TypeFox GmbH
+ * This program and the accompanying materials are made available under the
+ * terms of the MIT License, which is available in the project root.
+ ******************************************************************************/
+import type { SignatureHelp, SignatureHelpOptions, SignatureHelpParams } from 'vscode-languageserver';
+import { CancellationToken } from '../utils/cancellation.js';
+import type { AstNode } from '../syntax-tree.js';
+import type { MaybePromise } from '../utils/promise-utils.js';
+import type { LangiumDocument } from '../workspace/documents.js';
+/**
+ * Language-specific service for handling signature help requests.
+ */
+export interface SignatureHelpProvider {
+    /**
+     * Handles a signature help request
+     */
+    provideSignatureHelp(document: LangiumDocument, params: SignatureHelpParams, cancelToken?: CancellationToken): MaybePromise<SignatureHelp | undefined>;
+    /**
+     * Options that determine the server capabilities for a signature help request. It contains the list of triggering characters.
+     */
+    get signatureHelpOptions(): SignatureHelpOptions;
+}
+export declare abstract class AbstractSignatureHelpProvider implements SignatureHelpProvider {
+    provideSignatureHelp(document: LangiumDocument, params: SignatureHelpParams, cancelToken?: CancellationToken): MaybePromise<SignatureHelp | undefined>;
+    /**
+     * Override this method to return the desired SignatureHelp
+     */
+    protected abstract getSignatureFromElement(element: AstNode, cancelToken: CancellationToken): MaybePromise<SignatureHelp | undefined>;
+    /**
+     * Override this getter to return the list of triggering characters for your language. To deactivate the signature help, return an empty object.
+     */
+    get signatureHelpOptions(): SignatureHelpOptions;
+}
+/**
+ * Merges the SignatureHelpOptions of all languages
+ */
+export declare function mergeSignatureHelpOptions(options: Array<SignatureHelpOptions | undefined>): SignatureHelpOptions | undefined;
+//# sourceMappingURL=signature-help-provider.d.ts.map