Add support for sdk extensions when launched with a package root

lib/src/driver.dart

 // Copyright (c) 2015, 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 analyzer_cli.src.driver;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 255 matching lines @@
         /*Map<String, Uri> map = */pkgfile.parse(bytes, fileUri);
         // TODO(pquitslund): plug into new resolver once implemented
         // https://github.com/dart-lang/sdk/issues/23615
       } catch (e) {
         printAndFail(
             'Unable to read package config data from $packageConfigPath: $e');
       }
       printAndFail(
           'Package config files are not supported yet. For status see: https://github.com/dart-lang/sdk/issues/23373');
     } else if (options.packageRootPath != null) {
+      Map<String, List<fileSystem.Folder>> packageMap =
+          _PackageRootPackageMapBuilder.buildPackageMap(
+              options.packageRootPath);
+      if (packageMap != null) {
+        resolvers.add(new SdkExtUriResolver(packageMap));
+      }
       JavaFile packageDirectory = new JavaFile(options.packageRootPath);
       resolvers.add(new PackageUriResolver([packageDirectory]));
     } else {
       PubPackageMapProvider pubPackageMapProvider =
           new PubPackageMapProvider(PhysicalResourceProvider.INSTANCE, sdk);
       PackageMapInfo packageMapInfo = pubPackageMapProvider.computePackageMap(
           PhysicalResourceProvider.INSTANCE.getResource('.'));
       Map<String, List<fileSystem.Folder>> packageMap =
           packageMapInfo.packageMap;
       if (packageMap != null) {
@@ skipping 143 matching lines @@
     }
     return true;
   }
 
   /// Convert [sourcePath] into an absolute path.
   static String _normalizeSourcePath(String sourcePath) {
     return path.normalize(new File(sourcePath).absolute.path);
   }
 }
 
+/// [SdkExtUriResolver] needs a Map from package name to folder. In the case
+/// that the analyzer is invoked with a --package-root option, we need to
+/// manually create this mapping. Given [packageRootPath],
+/// [_PackageRootPackageMapBuilder] creates a simple mapping from package name
+/// to full path on disk (resolving any symbolic links).
+class _PackageRootPackageMapBuilder {
+  static Map<String, List<fileSystem.Folder>> buildPackageMap(
+      String packageRootPath) {
+    var packageRoot = new Directory(packageRootPath);
+    var packages = packageRoot.listSync(followLinks: false);
+    var result = new Map<String, List<fileSystem.Folder>>();
+    for (var package in packages) {
+      var packageName = path.basename(package.path);
+      var realPath = package.resolveSymbolicLinksSync();
+      result[packageName] = [
+        PhysicalResourceProvider.INSTANCE.getFolder(realPath)
+      ];
+    }
+    return result;
+  }
+}
+
 /// Provides a framework to read command line options from stdin and feed them
 /// to a callback.
 class _BatchRunner {
   /// Run the tool in 'batch' mode, receiving command lines through stdin and
   /// returning pass/fail status through stdout. This feature is intended for
   /// use in unit testing.
   static void runAsBatch(List<String> sharedArgs, _BatchRunnerHandler handler) {
     outSink.writeln('>>> BATCH START');
     Stopwatch stopwatch = new Stopwatch();
     stopwatch.start();
@@ skipping 37 matching lines @@
             '>>> TEST $resultPassString ${stopwatch.elapsedMilliseconds}ms');
       } catch (e, stackTrace) {
         errorSink.writeln(e);
         errorSink.writeln(stackTrace);
         errorSink.writeln('>>> EOF STDERR');
         outSink.writeln('>>> TEST CRASH');
       }
     });
   }
 }