Code generate Dart classes representing the analysis server API.

pkg/analysis_server/tool/spec/from_html.dart

 // Copyright (c) 2014, 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.
 
 /**
  * Code for reading an HTML API description.
  */
 library from.html;
 
 import 'dart:io';
@@ skipping 370 matching lines @@
       types.add(new TypeMap(keyType, valueType, child));
     },
     'enum': (dom.Element child) {
       types.add(typeEnumFromHtml(child));
     },
     'ref': (dom.Element child) {
       checkAttributes(child, []);
       types.add(new TypeReference(innerText(child), child));
     },
     'union': (dom.Element child) {
-      checkAttributes(child, []);
-      types.add(new TypeUnion(processContentsAsTypes(child), child));
+      checkAttributes(child, ['field']);
+      String field = child.attributes['field'];
+      types.add(new TypeUnion(processContentsAsTypes(child), field, child));
     }
   });
   return types;
 }
 
 /**
  * Create a [TypeEnum] from an HTML description.
  */
 TypeEnum typeEnumFromHtml(dom.Element html) {
   checkName(html, 'enum');
@@ skipping 90 matching lines @@
 
 /**
  * Read the API description from the file 'spec_input.html'.
  */
 Api readApi() {
   File htmlFile = new File('spec_input.html');
   String htmlContents = htmlFile.readAsStringSync();
   dom.Document document = parser.parse(htmlContents);
   return apiFromHtml(document.firstChild);
 }