Implemented support for trigger characters in signature help.

src/server/editorServices.ts

@@ -471,7 +471,7 @@ namespace ts.server {
 
             this.hostConfiguration = {
                 formatCodeOptions: getDefaultFormatCodeSettings(this.host),
-                preferences: defaultPreferences,
+                preferences: emptyOptions,
                 hostInfo: "Unknown host",
                 extraFileExtensions: []
             };

src/server/protocol.ts

@@ -1787,6 +1787,10 @@ namespace ts.server.protocol {
          * Optional prefix to apply to possible completions.
          */
         prefix?: string;
+        /**
+         * Character that was responsible for triggering completion.
+         * Should be `undefined` if a user manually requested completion.
+         */
         triggerCharacter?: CompletionsTriggerCharacter;
         /**
          * @deprecated Use UserPreferences.includeCompletionsForModuleExports
@@ -2048,10 +2052,17 @@ namespace ts.server.protocol {
         argumentCount: number;
     }
 
+    export type SignatureHelpTriggerCharacter = "," | "(" | "<";
+
     /**
      * Arguments of a signature help request.
      */
     export interface SignatureHelpRequestArgs extends FileLocationRequestArgs {
+        /**
+         * Character that was responsible for triggering signature help.
+         * Should be `undefined` if a user manually requested completion.
+         */
+        triggerCharacter?: SignatureHelpTriggerCharacter;
     }
 
     /**

src/server/scriptInfo.ts

@@ -419,7 +419,7 @@ namespace ts.server {
 
             if (preferences) {
                 if (!this.preferences) {
-                    this.preferences = defaultPreferences;
+                    this.preferences = emptyOptions;
                 }
                 this.preferences = { ...this.preferences, ...preferences };
             }

src/server/session.ts

@@ -1398,7 +1398,7 @@ namespace ts.server {
             const { file, project } = this.getFileAndProject(args);
             const scriptInfo = this.projectService.getScriptInfoForNormalizedPath(file)!;
             const position = this.getPosition(args, scriptInfo);
-            const helpItems = project.getLanguageService().getSignatureHelpItems(file, position);
+            const helpItems = project.getLanguageService().getSignatureHelpItems(file, position, args);
             if (!helpItems) {
                 return undefined;
             }