Detect and warn about missing scripts (rather than fail during the build)

pkg/polymer/lib/src/build/script_compactor.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.
 
 /// Transfomer that combines multiple dart script tags into a single one.
 library polymer.src.build.script_compactor;
 
 import 'dart:async';
 import 'dart:convert';
 
@@ skipping 121 matching lines @@
         logger.warning('unexpected script. The '
           'ScriptCompactor transformer should run after running the '
           'ImportInliner', span: tag.sourceSpan);
       }
     }
   }
 
   /// Emits the main HTML and Dart bootstrap code for the application. If there
   /// were not Dart entry point files, then this simply emits the original HTML.
   Future _emitNewEntrypoint(_) {
-    if (entryLibraries.isEmpty) {
-      // We didn't find code, nothing to do.
-      transform.addOutput(transform.primaryInput);
-      return null;
-    }
-
+    // If we don't find code, there is nothing to do.
+    if (entryLibraries.isEmpty) return null;
     return _initResolver()
         .then(_extractUsesOfMirrors)
         .then(_emitFiles)
         .whenComplete(() {
           if (resolver != null) resolver.release();
         });
   }
 
   /// Load a resolver that computes information for every library in
   /// [entryLibraries], then use it to initialize the [recorder] (for import
   /// resolution) and to resolve specific elements (for analyzing the user's
   /// code).
-  Future _initResolver() => resolvers.get(transform, entryLibraries).then((r) {
-    resolver = r;
-    types = new _ResolvedTypes(resolver);
-  });
+  Future _initResolver() {
+    // We include 'polymer.dart' to simplify how we do resolution below. This
+    // way we can assume polymer is there, even if the user didn't include an
+    // import to it.
+    var libsToLoad = [new AssetId('polymer', 'lib/polymer.dart')]

[Jennifer Messerly, 2014/04/18 00:53:33]

based on the test, is the idea here that we don't want to blow up if no polymer
import is there?
if so maybe note that without this code, it throws?

[Siggi Cherem (dart-lang), 2014/04/18 01:05:16]

Right
Done.

+        ..addAll(entryLibraries);
+    return resolvers.get(transform, libsToLoad).then((r) {
+      resolver = r;
+      types = new _ResolvedTypes(resolver);
+    });
+  }
 
   /// Inspects the entire program to find out anything that polymer accesses
   /// using mirrors and produces static information that can be used to replace
   /// the mirror-based loader and the uses of mirrors through the `smoke`
   /// package. This includes:
   ///
   ///   * visiting entry-libraries to extract initializers,
   ///   * visiting polymer-expressions to extract getters and setters,
   ///   * looking for published fields of custom elements, and
   ///   * looking for event handlers and callbacks of change notifications.
@@ skipping 164 matching lines @@
       code.writeln("import '$url' as i$i;");
       prefixes[id] = 'i$i';
       i++;
     }
 
     // Include smoke initialization.
     generator.writeImports(code);
     generator.writeTopLevelDeclarations(code);
     code.writeln('\nvoid main() {');
     generator.writeInitCall(code);
-    code.writeln('  startPolymer([');
+    code.write('  startPolymer([');
 
     // Include initializers to switch from mirrors_loader to static_loader.
-    for (var init in initializers) {
-      var initCode = init.asCode(prefixes[init.assetId]);
-      code.write("      $initCode,\n");
+    if (!initializers.isEmpty) {
+      code.writeln();
+      for (var init in initializers) {
+        var initCode = init.asCode(prefixes[init.assetId]);
+        code.write("      $initCode,\n");
+      }
+      code.writeln('    ]);');
+    } else {
+      logger.warning('no polymer initializers were found.');

[Jennifer Messerly, 2014/04/18 00:53:33]

I wonder if we should add more to this msg about how to fix this, if it happens?

[Siggi Cherem (dart-lang), 2014/04/18 01:05:16]

Good idea. Done.

+      code.writeln(']);');
     }
-    code..writeln('    ]);')
-        ..writeln('}');
+    code.writeln('}');
     transform.addOutput(new Asset.fromString(bootstrapId, code.toString()));
 
 
     // Emit the bootstrap .dart file
     var srcUrl = path.url.basename(bootstrapId.path);
     document.body.nodes.add(parseFragment(
           '<script type="application/dart" src="$srcUrl"></script>'));
     transform.addOutput(new Asset.fromString(docId, document.outerHtml));
   }
 
@@ skipping 322 matching lines @@
   for (var c in combinators) {
     if (c is ShowElementCombinator) {
       var show = c.shownNames.toSet();
       elements.retainWhere((e) => show.contains(e.displayName));
     } else if (c is HideElementCombinator) {
       var hide = c.hiddenNames.toSet();
       elements.removeWhere((e) => hide.contains(e.displayName));
     }
   }
 }