Add language filter panel.

extensions/ql-vscode/package.json

@@ -581,6 +581,10 @@
         "command": "codeQL.copyVersion",
         "title": "CodeQL: Copy Version Information"
       },
+      {
+        "command": "codeQLLanguageSelection.setSelectedItem",
+        "title": "Select"
+      },
       {
         "command": "codeQLQueries.runLocalQueryFromQueriesPanel",
         "title": "Run local query",
@@ -1163,6 +1167,11 @@
           "when": "view == codeQLVariantAnalysisRepositories && viewItem =~ /canImportCodeSearch/",
           "group": "2_qlContextMenu@1"
         },
+        {
+          "command": "codeQLLanguageSelection.setSelectedItem",
+          "when": "view == codeQLLanguageSelection && viewItem =~ /canBeSelected/",
+          "group": "inline"
+        },
         {
           "command": "codeQLDatabases.setCurrentDatabase",
           "group": "inline",
@@ -1511,6 +1520,10 @@
         {
           "command": "codeQL.openModelEditor"
         },
+        {
+          "command": "codeQLLanguageSelection.setSelectedItem",
+          "when": "false"
+        },
         {
           "command": "codeQLQueries.runLocalQueryContextMenu",
           "when": "false"
@@ -1977,6 +1990,11 @@
     },
     "views": {
       "ql-container": [
+        {
+          "id": "codeQLLanguageSelection",
+          "name": "Language",
+          "when": "config.codeQL.canary && config.codeQL.showLanguageFilter"
+        },
         {
           "id": "codeQLDatabases",
           "name": "Databases"

extensions/ql-vscode/src/common/commands.ts

@@ -12,6 +12,7 @@ import type {
 } from "../variant-analysis/shared/variant-analysis";
 import type { QLDebugConfiguration } from "../debugger/debug-configuration";
 import type { QueryTreeViewItem } from "../queries-panel/query-tree-view-item";
+import type { LanguageSelectionTreeViewItem } from "../language-selection-panel/language-selection-data-provider";
 
 // A command function matching the signature that VS Code calls when
 // a command is invoked from a context menu on a TreeView with
@@ -198,6 +199,13 @@ export type QueryHistoryCommands = {
   "codeQL.exportSelectedVariantAnalysisResults": () => Promise<void>;
 };
 
+// Commands user for the language selector panel
+export type LanguageSelectionCommands = {
+  "codeQLLanguageSelection.setSelectedItem": (
+    item: LanguageSelectionTreeViewItem,
+  ) => Promise<void>;
+};
+
 // Commands used for the local databases panel
 export type LocalDatabasesCommands = {
   // Command palette commands

extensions/ql-vscode/src/extension.ts

@@ -136,6 +136,7 @@ import { NewQueryRunner, QueryRunner, QueryServerClient } from "./query-server";
 import { QueriesModule } from "./queries-panel/queries-module";
 import { OpenReferencedFileCodeLensProvider } from "./local-queries/open-referenced-file-code-lens-provider";
 import { LanguageContextStore } from "./language-context-store";
+import { LanguageSelectionPanel } from "./language-selection-panel/language-selection-panel";
 
 /**
  * extension.ts
@@ -779,6 +780,10 @@ async function activateWithInstalledDistribution(
   void extLogger.log("Initializing language context.");
   const languageContext = new LanguageContextStore(app);
 
+  void extLogger.log("Initializing language selector.");
+  const languageSelectionPanel = new LanguageSelectionPanel(languageContext);
+  ctx.subscriptions.push(languageSelectionPanel);
+
   void extLogger.log("Initializing database panel.");
   const databaseUI = new DatabaseUI(
     app,
@@ -1016,6 +1021,7 @@ async function activateWithInstalledDistribution(
     ...getPackagingCommands({
       cliServer,
     }),
+    ...languageSelectionPanel.getCommands(),
     ...modelEditorModule.getCommands(),
     ...evalLogViewer.getCommands(),
     ...summaryLanguageSupport.getCommands(),

extensions/ql-vscode/src/language-context-store.ts

@@ -46,4 +46,11 @@ export class LanguageContextStore extends DisposableObject {
   public shouldInclude(language: QueryLanguage | undefined): boolean {
     return this.languageFilter === "All" || this.languageFilter === language;
   }
+
+  public selectedLanguage(language: QueryLanguage | undefined): boolean {
+    return (
+      (this.languageFilter === "All" && language === undefined) ||
+      this.languageFilter === language
+    );
+  }
 }

extensions/ql-vscode/src/language-selection-panel/language-selection-data-provider.ts

@@ -0,0 +1,93 @@
+import { DisposableObject } from "../common/disposable-object";
+import { LanguageContextStore } from "../language-context-store";
+import {
+  Event,
+  EventEmitter,
+  ThemeIcon,
+  TreeDataProvider,
+  TreeItem,
+} from "vscode";
+import {
+  QueryLanguage,
+  getLanguageDisplayName,
+} from "../common/query-language";
+
+const ALL_LANGUAGE_SELECTION_OPTIONS = [
+  undefined, // All langauges
+  QueryLanguage.Cpp,
+  QueryLanguage.CSharp,
+  QueryLanguage.Go,
+  QueryLanguage.Java,
+  QueryLanguage.Javascript,
+  QueryLanguage.Python,
+  QueryLanguage.Ruby,
+  QueryLanguage.Swift,
+];
+
+// A tree view items consisting of of a language (or undefined for all languages
+// and a boolean indicating whether it is selected or not.
+export class LanguageSelectionTreeViewItem extends TreeItem {
+  constructor(
+    public readonly language: QueryLanguage | undefined,
+    public readonly selected: boolean = false,
+  ) {
+    const label = language ? getLanguageDisplayName(language) : "All languages";
+    super(label);
+
+    this.iconPath = selected ? new ThemeIcon("check") : undefined;
+    this.contextValue = selected ? undefined : "canBeSelected";
+  }
+}
+
+export class LanguageSelectionTreeDataProvider
+  extends DisposableObject
+  implements TreeDataProvider<LanguageSelectionTreeViewItem>
+{
+  private treeItems: LanguageSelectionTreeViewItem[];
+  private readonly onDidChangeTreeDataEmitter = this.push(
+    new EventEmitter<void>(),
+  );
+
+  public constructor(private readonly languageContext: LanguageContextStore) {
+    super();
+
+    this.treeItems = this.createTree(languageContext);
+
+    // If the language context changes, we need to update the tree.
+    this.push(
+      this.languageContext.onLanguageContextChanged(() => {
+        this.treeItems = this.createTree(languageContext);
+        this.onDidChangeTreeDataEmitter.fire();
+      }),
+    );
+  }
+
+  public get onDidChangeTreeData(): Event<void> {
+    return this.onDidChangeTreeDataEmitter.event;
+  }
+
+  public getTreeItem(item: LanguageSelectionTreeViewItem): TreeItem {
+    return item;
+  }
+
+  public getChildren(
+    item?: LanguageSelectionTreeViewItem,
+  ): LanguageSelectionTreeViewItem[] {
+    if (!item) {
+      return this.treeItems;
+    } else {
+      return [];
+    }
+  }
+
+  private createTree(
+    languageContext: LanguageContextStore,
+  ): LanguageSelectionTreeViewItem[] {
+    return ALL_LANGUAGE_SELECTION_OPTIONS.map((language) => {
+      return new LanguageSelectionTreeViewItem(
+        language,
+        languageContext.selectedLanguage(language),
+      );
+    });
+  }
+}

extensions/ql-vscode/src/language-selection-panel/language-selection-panel.ts

@@ -0,0 +1,40 @@
+import { DisposableObject } from "../common/disposable-object";
+import { window } from "vscode";
+import {
+  LanguageSelectionTreeDataProvider,
+  LanguageSelectionTreeViewItem,
+} from "./language-selection-data-provider";
+import { LanguageContextStore } from "../language-context-store";
+import { LanguageSelectionCommands } from "../common/commands";
+
+// This panel allows the selection of a single language, that will
+// then filter all other relevant views (e.g. db panel, query history).
+export class LanguageSelectionPanel extends DisposableObject {
+  constructor(private readonly languageContext: LanguageContextStore) {
+    super();
+
+    const dataProvider = new LanguageSelectionTreeDataProvider(languageContext);
+
+    const treeView = window.createTreeView("codeQLLanguageSelection", {
+      treeDataProvider: dataProvider,
+    });
+    this.push(treeView);
+  }
+
+  public getCommands(): LanguageSelectionCommands {
+    return {
+      "codeQLLanguageSelection.setSelectedItem":
+        this.handleSetSelectedLanguage.bind(this),
+    };
+  }
+
+  private async handleSetSelectedLanguage(
+    item: LanguageSelectionTreeViewItem,
+  ): Promise<void> {
+    if (item.language) {
+      await this.languageContext.setLanguageContext(item.language);
+    } else {
+      await this.languageContext.clearLanguageContext();
+    }
+  }
+}

extensions/ql-vscode/test/unit-tests/command-lint.test.ts

@@ -38,6 +38,7 @@ describe("commands declared in package.json", () => {
       expect(title).toBeDefined();
       commandTitles[command] = title!;
     } else if (
+      command.match(/^codeQLLanguageSelection\./) ||
       command.match(/^codeQLDatabases\./) ||
       command.match(/^codeQLQueries\./) ||
       command.match(/^codeQLVariantAnalysisRepositories\./) ||