typescript-language-server · rchl · Aug 8, 2022 · Aug 7, 2022 · Aug 7, 2022
diff --git a/src/hover.ts b/src/hover.ts
@@ -4,22 +4,42 @@
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
  */
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
 
 import * as lsp from 'vscode-languageserver';
 import type tsp from 'typescript/lib/protocol.d.js';
 import { asDocumentation, asPlainText } from './protocol-translation.js';
 
-export function asSignatureHelp(info: tsp.SignatureHelpItems): lsp.SignatureHelp {
+export function asSignatureHelp(info: tsp.SignatureHelpItems, context?: lsp.SignatureHelpContext): lsp.SignatureHelp {
+    const signatures = info.items.map(asSignatureInformation);
     return {
-        activeSignature: info.selectedItemIndex,
+        activeSignature: getActiveSignature(info, signatures, context),
         activeParameter: getActiveParameter(info),
-        signatures: info.items.map(asSignatureInformation)
+        signatures
     };
 }
 
+function getActiveSignature(info: tsp.SignatureHelpItems, signatures: readonly lsp.SignatureInformation[], context?: lsp.SignatureHelpContext): number {
+    // Try matching the previous active signature's label to keep it selected
+    if (context?.activeSignatureHelp?.activeSignature !== undefined) {
+        const previouslyActiveSignature = context.activeSignatureHelp.signatures[context.activeSignatureHelp.activeSignature];
+        if (previouslyActiveSignature && context.isRetrigger) {
+            const existingIndex = signatures.findIndex(other => other.label === previouslyActiveSignature.label);
+            if (existingIndex !== -1) {
+                return existingIndex;
+            }
+        }
+    }
+
+    return info.selectedItemIndex;
+}
+
 function getActiveParameter(info: tsp.SignatureHelpItems): number {
     const activeSignature = info.items[info.selectedItemIndex];
-    if (activeSignature && activeSignature.isVariadic) {
+    if (activeSignature?.isVariadic) {
         return Math.min(info.argumentIndex, activeSignature.parameters.length - 1);
     }
     return info.argumentIndex;
@@ -46,3 +66,23 @@ function asParameterInformation(parameter: tsp.SignatureHelpParameter): lsp.Para
         documentation: asDocumentation(parameter)
     };
 }
+
+export function toTsTriggerReason(context: lsp.SignatureHelpContext): tsp.SignatureHelpTriggerReason {
+    switch (context.triggerKind) {
+        case lsp.SignatureHelpTriggerKind.TriggerCharacter:
+            if (context.triggerCharacter) {
+                if (context.isRetrigger) {
+                    return { kind: 'retrigger', triggerCharacter: context.triggerCharacter as any };
+                } else {
+                    return { kind: 'characterTyped', triggerCharacter: context.triggerCharacter as any };
+                }
+            } else {
+                return { kind: 'invoked' };
+            }
+        case lsp.SignatureHelpTriggerKind.ContentChange:
+            return context.isRetrigger ? { kind: 'retrigger' } : { kind: 'invoked' };
+        case lsp.SignatureHelpTriggerKind.Invoked:
+        default:
+            return { kind: 'invoked' };
+    }
+}
diff --git a/src/lsp-server.spec.ts b/src/lsp-server.spec.ts
@@ -881,6 +881,7 @@ describe('signatureHelp', () => {
             version: 1,
             text: `
         export function foo(bar: string, baz?:boolean): void {}
+        export function foo(n: number, baz?: boolean): void
         foo(param1, param2)
       `
         };
@@ -892,6 +893,8 @@ describe('signatureHelp', () => {
             position: position(doc, 'param1')
         }))!;
 
+        assert.equal(result.signatures.length, 2);
+
         assert.equal('bar: string', result.signatures[result.activeSignature!].parameters![result.activeParameter!].label);
 
         result = (await server.signatureHelp({
@@ -901,6 +904,43 @@ describe('signatureHelp', () => {
 
         assert.equal('baz?: boolean', result.signatures[result.activeSignature!].parameters![result.activeParameter!].label);
     });
+
+    it('retrigger with specific signature active', async () => {
+        const doc = {
+            uri: uri('bar.ts'),
+            languageId: 'typescript',
+            version: 1,
+            text: `
+        export function foo(bar: string, baz?: boolean): void {}
+        export function foo(n: number, baz?: boolean): void
+        foo(param1, param2)
+      `
+        };
+        server.didOpenTextDocument({ textDocument: doc });
+        let result = await server.signatureHelp({
+            textDocument: doc,
+            position: position(doc, 'param1')
+        });
+        assert.equal(result!.signatures.length, 2);
+
+        result = (await server.signatureHelp({
+            textDocument: doc,
+            position: position(doc, 'param1'),
+            context: {
+                isRetrigger: true,
+                triggerKind: lsp.SignatureHelpTriggerKind.Invoked,
+                activeSignatureHelp: {
+                    signatures: result!.signatures,
+                    activeSignature: 1  // select second signature
+                }
+            }
+        }))!;
+        const { activeSignature, signatures } = result!;
+        assert.equal(activeSignature, 1);
+        assert.deepInclude(signatures[activeSignature!], {
+            label: 'foo(n: number, baz?: boolean): void'
+        });
+    });
 });
 
 describe('code actions', () => {

diff --git a/src/lsp-server.ts b/src/lsp-server.ts
@@ -26,7 +26,7 @@ import {
 } from './protocol-translation.js';
 import { LspDocuments, LspDocument } from './document.js';
 import { asCompletionItem, asResolvedCompletionItem, getCompletionTriggerCharacter } from './completion.js';
-import { asSignatureHelp } from './hover.js';
+import { asSignatureHelp, toTsTriggerReason } from './hover.js';
 import { Commands } from './commands.js';
 import { provideQuickFix } from './quickfix.js';
 import { provideRefactors } from './refactor.js';
@@ -326,7 +326,8 @@ export class LspServer {
                 renameProvider: true,
                 referencesProvider: true,
                 signatureHelpProvider: {
-                    triggerCharacters: ['(', ',', '<']
+                    triggerCharacters: ['(', ',', '<'],
+                    retriggerCharacters: [')']
                 },
                 workspaceSymbolProvider: true,
                 implementationProvider: true,
@@ -861,25 +862,27 @@ export class LspServer {
         return opts;
     }
 
-    async signatureHelp(params: lsp.TextDocumentPositionParams): Promise<lsp.SignatureHelp | undefined> {
+    async signatureHelp(params: lsp.SignatureHelpParams): Promise<lsp.SignatureHelp | undefined> {
         const file = uriToPath(params.textDocument.uri);
         this.logger.log('signatureHelp', params, file);
         if (!file) {
             return undefined;
         }
 
-        const response = await this.interuptDiagnostics(() => this.getSignatureHelp(file, params.position));
+        const response = await this.interuptDiagnostics(() => this.getSignatureHelp(file, params));
         if (!response || !response.body) {
             return undefined;
         }
-        return asSignatureHelp(response.body);
+        return asSignatureHelp(response.body, params.context);
     }
-    protected async getSignatureHelp(file: string, position: lsp.Position): Promise<tsp.SignatureHelpResponse | undefined> {
+    protected async getSignatureHelp(file: string, params: lsp.SignatureHelpParams): Promise<tsp.SignatureHelpResponse | undefined> {
         try {
+            const { position, context } = params;
             return await this.tspClient.request(CommandTypes.SignatureHelp, {
                 file,
                 line: position.line + 1,
-                offset: position.character + 1
+                offset: position.character + 1,
+                triggerReason: context ? toTsTriggerReason(context) : undefined
             });
         } catch (err) {
             return undefined;

diff --git a/tsconfig.json b/tsconfig.json
@@ -18,6 +18,7 @@
             "es6"
         ],
         "alwaysStrict": true,
+        "strictBindCallApply": true,
         "strictNullChecks": true,
         "skipLibCheck": true,
     }