Support sourceing files in patches.

lib/compiler/implementation/scanner/scanner_task.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.
 
 class ScannerTask extends CompilerTask {
   ScannerTask(Compiler compiler) : super(compiler);
   String get name() => 'Scanner';
 
   void scanLibrary(LibraryElement library) {
     var compilationUnit = library.entryCompilationUnit;
@@ skipping 40 matching lines @@
         imports.addLast(tag);
       } else if (tag.isLibrary()) {
         tagState = checkTag(TagState.LIBRARY, tag);
         if (library.libraryTag !== null) {
           compiler.cancel("duplicated library declaration", node: tag);
         } else {
           library.libraryTag = tag;
         }
       } else if (tag.isSource()) {
         tagState = checkTag(TagState.SOURCE, tag);
-        Script script = compiler.readScript(resolved, tag);
-        CompilationUnitElement unit =
-            new CompilationUnitElement(script, library);
-        compiler.withCurrentElement(unit, () => scan(unit));
+        compiler.scanner.sourceTagInLibrary(tag, resolved, library);
       } else if (tag.isResource()) {
         tagState = checkTag(TagState.RESOURCE, tag);
         compiler.reportWarning(tag, 'ignoring resource tag');
       } else {
         compiler.cancel("illegal script tag: ${tag.tag}", node: tag);
       }
     }
 
     // Apply patch, if any.
     if (library.uri.scheme == 'dart') {
       compiler.patchDartLibrary(library, library.uri.path);
     }
 
     // Now that we have processed all the source tags, it is safe to
     // start loading other libraries.
 
     if (library.uri.scheme != 'dart' || library.uri.path != 'core') {
       compiler.importCoreLibrary(library);
     }
 
     for (ScriptTag tag in imports.toLink()) {
       importLibraryFromTag(tag, library.entryCompilationUnit);
     }
   }
 
   /**
+   * Source a tag in the scope of [library]. The [path] given is used as is,

[Mads Ager (google), 2012/08/22 07:40:03]

Handle a source tag in the scope of [library]?

At least in my mind you source a file/script with a source tag, but you don't
source a tag?

[Anders Johnsen, 2012/08/22 13:02:27]

Done.

+   * any resolve should be done beforehand.

[Mads Ager (google), 2012/08/22 07:40:03]

any resolution

[Anders Johnsen, 2012/08/22 13:02:27]

Done.

+   */
+  void sourceTagInLibrary(ScriptTag tag, Uri path, LibraryElement library) {

[Mads Ager (google), 2012/08/22 07:40:03]

Rename. sourceScript? importSourceFromTag (to match importLibraryFromTag)?

[Anders Johnsen, 2012/08/22 13:02:27]

Done.

+    Script script = compiler.readScript(path, tag);
+    CompilationUnitElement unit = new CompilationUnitElement(script, library);
+    compiler.withCurrentElement(unit, () => compiler.scanner.scan(unit));
+  }
+
+  /**
    * Handle an import script tag by importing the referenced library into the
    * current library.
    * Returns the resolved library [Uri].
    */
   Uri importLibraryFromTag(ScriptTag tag,
                            CompilationUnitElement compilationUnit) {
     Uri base = compilationUnit.script.uri;
     StringNode argument = tag.argument;
     Uri resolved = base.resolve(argument.dartString.slowToString());
     LibraryElement importedLibrary = loadLibrary(resolved, argument, resolved);
@@ skipping 120 matching lines @@
   static final int RESOURCE = 4;
 
   /** Next state. */
   static final List<int> NEXT =
       const <int>[NO_TAG_SEEN,
                   IMPORT, // Only one library tag is allowed.
                   IMPORT,
                   SOURCE,
                   RESOURCE];
 }