navigator-decorator: add symlink icon and tooltip to linked files

This commit adds a new decorator for the file navigator. It displays a
downward right curved arrow at the tail of a file node if that file
contains a symbolic link. A tooltip is also added displaying "Symbolic
Link" when hovering over a symbolic linked file node.

packages/navigator/src/browser/navigator-frontend-module.ts

@@ -41,6 +41,7 @@ import { bindContributionProvider } from '@theia/core/lib/common';
 import { OpenEditorsTreeDecorator } from './open-editors-widget/navigator-open-editors-decorator-service';
 import { OpenEditorsWidget } from './open-editors-widget/navigator-open-editors-widget';
 import { NavigatorTreeDecorator } from './navigator-decorator-service';
+import { NavigatorSymlinkDecorator } from './navigator-symlink-decorator';
 
 export default new ContainerModule(bind => {
     bindFileNavigatorPreferences(bind);
@@ -78,4 +79,7 @@ export default new ContainerModule(bind => {
     bind(NavigatorTabBarDecorator).toSelf().inSingletonScope();
     bind(FrontendApplicationContribution).toService(NavigatorTabBarDecorator);
     bind(TabBarDecorator).toService(NavigatorTabBarDecorator);
+
+    bind(NavigatorSymlinkDecorator).toSelf().inSingletonScope();
+    bind(NavigatorTreeDecorator).toService(NavigatorSymlinkDecorator);
 });

packages/navigator/src/browser/navigator-symlink-decorator.ts

@@ -0,0 +1,65 @@
+/********************************************************************************
+ * Copyright (C) 2021 Ericsson and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the Eclipse
+ * Public License v. 2.0 are satisfied: GNU General Public License, version 2
+ * with the GNU Classpath Exception which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ ********************************************************************************/
+
+import { inject, injectable } from '@theia/core/shared/inversify';
+import { Emitter, Event, nls } from '@theia/core';
+import { TreeDecorator, Tree, TreeDecoration, DepthFirstTreeIterator } from '@theia/core/lib/browser';
+import { FileStatNode } from '@theia/filesystem/lib/browser';
+import { DecorationsService } from '@theia/core/lib/browser/decorations-service';
+
+@injectable()
+export class NavigatorSymlinkDecorator implements TreeDecorator {
+
+    readonly id = 'theia-navigator-symlink-decorator';
+
+    constructor(@inject(DecorationsService) protected readonly decorationsService: DecorationsService) {
+        this.decorationsService.onDidChangeDecorations(() => {
+            this.fireDidChangeDecorations((tree: Tree) => this.collectDecorator(tree));
+        });
+    }
+
+    async decorations(tree: Tree): Promise<Map<string, TreeDecoration.Data>> {
+        return this.collectDecorator(tree);
+    }
+
+    protected collectDecorator(tree: Tree): Map<string, TreeDecoration.Data> {
+        const result = new Map<string, TreeDecoration.Data>();
+        if (tree.root === undefined) {
+            return result;
+        }
+        for (const node of new DepthFirstTreeIterator(tree.root)) {
+            if (FileStatNode.is(node) && node.fileStat.isSymbolicLink) {
+                const decorations: TreeDecoration.Data = {
+                    tooltip: nls.localizeByDefault('Symbolic Link'),
+                    tailDecorations: [{ data: '\u2937' }]
+                };
+                result.set(node.id, decorations);
+            }
+        }
+        return result;
+    }
+
+    protected readonly emitter = new Emitter<(tree: Tree) => Map<string, TreeDecoration.Data>>();
+
+    get onDidChangeDecorations(): Event<(tree: Tree) => Map<string, TreeDecoration.Data>> {
+        return this.emitter.event;
+    }
+
+    fireDidChangeDecorations(event: (tree: Tree) => Map<string, TreeDecoration.Data>): void {
+        this.emitter.fire(event);
+    }
+
+}