Don't use regular expressions in Loader.

lib/src/yaml_node.dart

 // Copyright (c) 2012, 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 yaml.yaml_node;
 
 import 'dart:collection' as collection;
 
 import 'package:collection/collection.dart';
 import 'package:source_span/source_span.dart';
 
+import 'event.dart';
 import 'null_span.dart';
 import 'style.dart';
 import 'yaml_node_wrapper.dart';
 
 /// An interface for parsed nodes from a YAML source tree.
 ///
 /// [YamlMap]s and [YamlList]s implement this interface in addition to the
 /// normal [Map] and [List] interfaces, so any maps and lists will be
 /// [YamlNode]s regardless of how they're accessed.
 ///
@@ skipping 134 matching lines @@
   /// will have a reasonable implementation of [SourceSpan.message]. If
   /// [sourceUrl] is passed, it's used as the [SourceSpan.sourceUrl].
   ///
   /// [sourceUrl] may be either a [String], a [Uri], or `null`.
   YamlScalar.wrap(this.value, {sourceUrl})
       : style = ScalarStyle.ANY {
     _span = new NullSpan(sourceUrl);
   }
 
   /// Users of the library should not use this constructor.
-  YamlScalar.internal(this.value, SourceSpan span, this.style) {
+  YamlScalar.internal(this.value, ScalarEvent scalar)
+      : style = scalar.style {
     _span = span;
   }
 
+  /// Users of the library should not use this constructor.
+  YamlScalar.internalWithSpan(this.value, SourceSpan span)
+      : style = ScalarStyle.ANY {
+    _span = span;
+  }
+
   String toString() => value.toString();
 }
 
 /// Sets the source span of a [YamlNode].
 ///
 /// This method is not exposed publicly.
 void setSpan(YamlNode node, SourceSpan span) {
   node._span = span;
 }