Change the URL-space exposed by the browser server.

lib/src/util/path_handler.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library test.util.path_handler;
+
+import 'package:path/path.dart' as p;
+import 'package:shelf/shelf.dart' as shelf;
+
+import '../utils.dart';
+
+/// A handler that routes to sub-handlers based on exact path prefixes.
+class PathHandler {
+  /// A trie of path components to handlers.
+  final _paths = new _Node();
+
+  /// The shelf handler.
+  shelf.Handler get handler => _onRequest;
+
+  PathHandler();
+
+  /// Routes requests at or under [path] to [handler].
+  ///
+  /// If [path] is a parent or child directory of another path in this handler,
+  /// the longest matching prefix wins.
+  void add(String path, shelf.Handler handler) {
+    var node = _paths;
+    for (var component in p.url.split(path)) {
+      node = node.children.putIfAbsent(component, () => new _Node());
+    }
+    node.handler = handler;
+  }
+
+  _onRequest(shelf.Request request) {
+    var handler;
+    var handlerIndex;
+    var node = _paths;
+    var components = p.url.split(shelfUrl(request).path);
+    for (var i = 0; i < components.length; i++ ) {
+      node = node.children[components[i]];
+      if (node == null) break;
+      if (node.handler == null) continue;
+      handler = node.handler;
+      handlerIndex = i;
+    }
+
+    if (handler == null) return new shelf.Response.notFound("Not found.");
+
+    return handler(shelfChange(request,
+        path: p.joinAll(components.take(handlerIndex + 1))));
+  }
+}
+
+/// A trie node.
+class _Node {
+  shelf.Handler handler;
+  final children = new Map<String, _Node>();
+}