Add widget to display errors, and report dependency_graph errors correctly

lib/runtime/messages_widget.dart

Index: lib/runtime/messages_widget.dart
diff --git a/lib/runtime/messages_widget.dart b/lib/runtime/messages_widget.dart
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+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file

[Siggi Cherem (dart-lang), 2015/03/07 02:43:01]

this is adapted from the code in polymer. Simplified a bit and adjusted to use
the messages.json that we already produce in our summary reporter.

+// 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.
+
+/// This library provides a single function called injectLogs which when called
+/// will request a logs json file and build a small widget out of them which
+/// groups the logs by level.
+library polymer.build.log_injector;
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:html';
+
+import 'package:path/path.dart' as path;
+import 'package:source_span/source_span.dart';
+import 'package:dev_compiler/src/summary.dart';
+
+main() async => displayMessages(await HttpRequest.getString('messages.json'));
+
+void displayMessages(String data) {
+  var summary = GlobalSummary.parse(JSON.decode(data));
+  var messagesByLevel = _getMessagesByLevel(summary);
+  if (messagesByLevel.isEmpty) return;
+
+  // Build the wrapper, menu, and content divs.
+  var menuWrapper = new DivElement()..classes.add('menu');
+  var contentWrapper = new DivElement()..classes.add('content');
+  var wrapperDiv = new DivElement()
+    ..classes.add('dev-compiler-messages')
+    ..append(menuWrapper)
+    ..append(contentWrapper);
+
+  var selectedMenu = new _Selection();
+  var selectedContent = new _Selection();
+
+  // Add a menu item, content section, and messages for each log level.
+  messagesByLevel.forEach((level, messages) {
+    var contentItem = new DivElement()..classes.add(level);
+    var menuItem = new Element.html('<div class="$level">'
+        '$level <span class="num">(${messages.length})</span>'
+        '</div>');
+    menuWrapper.append(menuItem);
+    contentWrapper.append(contentItem);
+    menuItem.onClick.listen((_) {
+      selectedMenu.select(menuItem);
+      selectedContent.select(contentItem);
+    });
+
+    // TODO(sigmund): add permanent links to error messages like in polymer.
+    for (var m in messages) {
+      var message = _hyperlinkUrls(_escape(m.message));
+      var span = m.span;
+      var sb = new StringBuffer();
+      sb.write('<div class="message"><div class="text $level">$message</div>');
+      if (span != null) {
+        sb.write('<div class="location">'
+            '  <span class="location">${span.start.toolString}</span></div>'
+            '  <span class="text">${_escape(span.text)}</span></div></div>');
+      }
+      sb.write('</div>');
+
+      var logElement = new Element.html('$sb',
+          validator: new NodeValidatorBuilder.common()
+        ..allowNavigation(new _OpenUriPolicy()));
+      contentItem.append(logElement);
+      var messageElement = logElement.querySelector('div.text');
+      messageElement.onClick.listen((e) {
+        if (e.target == messageElement) {
+          messageElement.classes.toggle('expanded');
+        }
+      });
+    }
+  });
+
+  document.body.append(wrapperDiv);
+}
+
+/// Toggles classes to match which item of a list of items is selected.
+class _Selection {
+  Element _selected;
+
+  select(Element newItem) {
+    if (_selected == newItem) {
+      _selected = null;
+    } else {
+      if (_selected != null) {
+        _selected.classes.remove('active');
+      }
+      _selected = newItem;
+    }
+    newItem.classes.toggle('active');
+  }
+}
+
+final _urlRegex = new RegExp('http://[^ ]*');
+final _escaper = new HtmlEscape();
+String _hyperlinkUrls(String text) => text.replaceAllMapped(_urlRegex,
+    (m) => '<a href="${m.group(0)}" target="blank">${m.group(0)}</a>');
+String _escape(String text) => _escaper.convert(text);
+
+class _OpenUriPolicy implements UriPolicy {
+  bool allowsUri(String uri) => true;
+}
+
+Map<String, List<MessageSummary>> _getMessagesByLevel(GlobalSummary messages) {
+  var visitor = new _Visitor();
+  messages.accept(visitor);
+  return visitor.messagesByLevel;
+}
+
+class _Visitor extends RecursiveSummaryVisitor {
+  final Map<String, List<MessageSummary>> messagesByLevel = {};
+
+  @override
+  void visitMessage(MessageSummary message) {
+    var level = message.level.toLowerCase();
+    messagesByLevel.putIfAbsent(level, () => []);
+    messagesByLevel[level].add(message);
+  }
+}