Remove platform.js from polymer.html, hint in the linter that it should be used

pkg/polymer/lib/src/build/linter.dart

 // Copyright (c) 2013, 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.
 
 /// Logic to validate that developers are correctly using Polymer constructs.
 /// This is mainly used to produce warnings for feedback in the editor.
 library polymer.src.build.linter;
 
 import 'dart:async';
 
@@ skipping 19 matching lines @@
 
   Future apply(Transform transform) {
     var seen = new Set<AssetId>();
     var primary = transform.primaryInput;
     var id = primary.id;
     transform.addOutput(primary); // this phase is analysis only
     seen.add(id);
     return readPrimaryAsHtml(transform).then((document) {
       return _collectElements(document, id, transform, seen).then((elements) {
         bool isEntrypoint = options.isHtmlEntryPoint(id);
-        new _LinterVisitor(transform.logger, elements, isEntrypoint)
+        new _LinterVisitor(id, transform.logger, elements, isEntrypoint)
             .run(document);
       });
     });
   }
 
   /// Collect into [elements] any data about each polymer-element defined in
   /// [document] or any of it's imports, unless they have already been [seen].
   /// Elements are added in the order they appear, transitive imports are added
   /// first.
   Future<Map<String, _ElementSummary>> _collectElements(
       Document document, AssetId sourceId, Transform transform,
       Set<AssetId> seen, [Map<String, _ElementSummary> elements]) {
     if (elements == null) elements = <String, _ElementSummary>{};
     return _getImportedIds(document, sourceId, transform)
         // Note: the import order is relevant, so we visit in that order.
         .then((ids) => Future.forEach(ids,
               (id) => _readAndCollectElements(id, transform, seen, elements)))
-        .then((_) => _addElements(document, transform.logger, elements))
+        .then((_) {
+          if (sourceId.package == 'polymer' &&
+              sourceId.path == 'lib/src/js/polymer/polymer.html' &&
+              elements['polymer-element'] == null) {
+            elements['polymer-element'] =
+                new _ElementSummary('polymer-element', null, null);
+          }
+          return _addElements(document, transform.logger, elements);
+        })
         .then((_) => elements);
   }
 
   Future _readAndCollectElements(AssetId id, Transform transform,
       Set<AssetId> seen, Map<String, _ElementSummary> elements) {
     if (id == null || seen.contains(id)) return new Future.value(null);
     seen.add(id);
     return readAsHtml(id, transform).then(
         (doc) => _collectElements(doc, id, transform, seen, elements));
   }
@@ skipping 61 matching lines @@
   String get baseExtendsTag => extendsType == null
       ? extendsTag : extendsType.baseExtendsTag;
 
   _ElementSummary(this.tagName, this.extendsTag, this.span);
 
   String toString() => "($tagName <: $extendsTag)";
 }
 
 class _LinterVisitor extends TreeVisitor {
   TransformLogger _logger;
+  AssetId _sourceId;
   bool _inPolymerElement = false;
   bool _dartTagSeen = false;
   bool _polymerHtmlSeen = false;
   bool _polymerExperimentalHtmlSeen = false;
   bool _isEntrypoint;
   Map<String, _ElementSummary> _elements;
 
-  _LinterVisitor(this._logger, this._elements, this._isEntrypoint) {
+  _LinterVisitor(
+      this._sourceId, this._logger, this._elements, this._isEntrypoint) {
     // We normalize the map, so each element has a direct reference to any
     // element it extends from.
     for (var tag in _elements.values) {
       var extendsTag = tag.extendsTag;
       if (extendsTag == null) continue;
       tag.extendsType = _elements[extendsTag];
     }
   }
 
   void visitElement(Element node) {
     switch (node.localName) {
       case 'link': _validateLinkElement(node); break;
       case 'element': _validateElementElement(node); break;
       case 'polymer-element': _validatePolymerElement(node); break;
       case 'script': _validateScriptElement(node); break;
       default:
          _validateNormalElement(node);
          super.visitElement(node);
          break;
     }
   }
 
   void run(Document doc) {
     visit(doc);
 
-    if (_isEntrypoint && !_polymerHtmlSeen && !_polymerExperimentalHtmlSeen) {
-      _logger.warning(USE_POLYMER_HTML, span: doc.body.sourceSpan);
-    }
-
     if (_isEntrypoint && !_dartTagSeen && !_polymerExperimentalHtmlSeen) {
       _logger.warning(USE_INIT_DART, span: doc.body.sourceSpan);
     }
   }
 
   /// Produce warnings for invalid link-rel tags.
   void _validateLinkElement(Element node) {
     var rel = node.attributes['rel'];
     if (rel != 'import' && rel != 'stylesheet') return;
 
     if (rel == 'import' && _dartTagSeen) {
       _logger.warning("Move HTML imports above your Dart script tag.",
           span: node.sourceSpan);
     }
 
     var href = node.attributes['href'];
     if (href == null || href == '') {
       _logger.warning('link rel="$rel" missing href.', span: node.sourceSpan);
       return;
     }
 
-    if (href == 'packages/polymer/polymer.html') {
-      _polymerHtmlSeen = true;
-    } else if (href == POLYMER_EXPERIMENTAL_HTML) {
+    if (rel != 'import') return;
+
+    if (_inPolymerElement) {
+      _logger.error(NO_IMPORT_WITHIN_ELEMENT, span: node.sourceSpan);

[Siggi Cherem (dart-lang), 2014/06/13 20:08:37]

this is unrelated to the rest of the changes, but should at least warn about
https://code.google.com/p/dart/issues/detail?id=18340

+      return;
+    }
+
+    if (href == POLYMER_EXPERIMENTAL_HTML) {
       _polymerExperimentalHtmlSeen = true;
     }
     // TODO(sigmund): warn also if href can't be resolved.
   }
 
   /// Produce warnings if using `<element>` instead of `<polymer-element>`.
   void _validateElementElement(Element node) {
     _logger.warning('<element> elements are not supported, use'
         ' <polymer-element> instead', span: node.sourceSpan);
   }
 
   /// Produce warnings if using `<polymer-element>` in the wrong place or if the
   /// definition is not complete.
   void _validatePolymerElement(Element node) {
+    if (!_elements.containsKey('polymer-element')) {
+      _logger.warning(usePolymerHtmlMessageFrom(_sourceId),
+          span: node.sourceSpan);
+    }
+
     if (_inPolymerElement) {
       _logger.error('Nested polymer element definitions are not allowed.',
           span: node.sourceSpan);
       return;
     }
 
     var tagName = node.attributes['name'];
     var extendsTag = node.attributes['extends'];
 
     if (tagName == null) {
@@ skipping 169 matching lines @@
           'in your custom element "void handlerName(event, detail, target)" '
           'and use the form $name="{{handlerName}}".',
           span: node.attributeSpans[name]);
     }
   }
 }
 
 const String ONLY_ONE_TAG =
     'Only one "application/dart" script tag per document is allowed.';
 
-const String USE_POLYMER_HTML =
-    'Besides the initPolymer invocation, to run a polymer application you need '
-    'to include the following HTML import: '
-    '<link rel="import" href="packages/polymer/polymer.html">. This will '
-    'include the common polymer logic needed to boostrap your application.';
+String usePolymerHtmlMessageFrom(AssetId id) {
+  var segments = id.path.split('/');
+  var upDirCount = 0;
+  if (segments[0] == 'lib') {
+    // lib/foo.html => ../../packages/
+    upDirCount = segments.length;
+  } else if (segments.length > 2) {
+    // web/a/foo.html => ../packages/
+    upDirCount = segments.length - 2;
+  }
+  return usePolymerHtmlMessage(upDirCount);
+}
+
+String usePolymerHtmlMessage(int upDirCount) {
+  var reachOutPrefix = '../' * upDirCount;
+  return 'Missing definition for <polymer-element>, please add the following '
+    'HTML import at the top of this file: <link rel="import" '
+    'href="${reachOutPrefix}packages/polymer/polymer.html">.';
+}
+
+const String NO_IMPORT_WITHIN_ELEMENT = 'HTML imports are not supported '

[Jennifer Messerly, 2014/06/13 21:07:47]

maybe improve the wording so it's clearly an issue with our Polymer.dart deploy
tool?

The web components folks get grumpy if we appear to be saying something in the
standard is not supported. :)

[Siggi Cherem (dart-lang), 2014/06/13 22:15:28]

Done.

+    'within polymer element definitions, yet. Please move the import out of '
+    'this <polymer-element>.';
 
 const String USE_INIT_DART =
     'To run a polymer application, you need to call "initPolymer". You can '
     'either include a generic script tag that does this for you:'
     '\'<script type="application/dart">export "package:polymer/init.dart";'
     '</script>\' or add your own script tag and call that function. '
     'Make sure the script tag is placed after all HTML imports.';
 
 const String NO_DART_SCRIPT_AND_EXPERIMENTAL =
     'The experimental bootstrap feature doesn\'t support script tags on '
     'the main document (for now).';