Split analyzer2dart code into multiple source files

pkg/analyzer2dart/lib/src/driver.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.
+
+library analyzer2dart.driver;
+
+import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/java_io.dart';
+import 'package:analyzer/src/generated/sdk_io.dart';
+import 'package:analyzer/src/generated/source_io.dart';
+
+import 'closed_world.dart';
+import 'tree_shaker.dart';
+
+/**
+ * Top level driver for Analyzer2Dart.
+ */
+class Driver {
+  AnalysisContext context;
+
+  Driver() : context = AnalysisEngine.instance.createAnalysisContext() {
+    // Set up the source factory.
+    // TODO(paulberry): do we want to use ExplicitPackageUriResolver?
+    List<UriResolver> uriResolvers = [
+        new FileUriResolver(),
+        new DartUriResolver(DirectoryBasedDartSdk.defaultSdk) /* ,
+        new PackageUriResolver(packagesDirectories) */
+    ];
+    context.sourceFactory = new SourceFactory(uriResolvers);
+  }
+
+  /**
+   * Compute the closed world that is reachable from an entry point.
+   */
+  ClosedWorld computeWorld(FunctionElement entryPointElement) {
+    TreeShaker treeShaker = new TreeShaker();
+    treeShaker.add(entryPointElement);
+    return treeShaker.shake(entryPointElement.context);
+  }
+
+  /**
+   * Given a source, resolve it and return its entry point.
+   */
+  FunctionElement resolveEntryPoint(Source source) {
+    // Get the library element associated with the source.
+    LibraryElement libraryElement = context.computeLibraryElement(source);
+
+    // Get the resolved AST for main
+    FunctionElement entryPointElement = libraryElement.entryPoint;
+    if (entryPointElement == null) {
+      throw new Exception('No main()!');
+    }
+    return entryPointElement;
+  }
+
+  /**
+   * Add the given file as the root of analysis, and return the corresponding
+   * source.
+   */
+  Source setRealRoot(String path) {
+    // Tell the analysis server about the root
+    ChangeSet changeSet = new ChangeSet();
+    JavaFile javaFile = new JavaFile(path);
+    Source source = new FileBasedSource.con1(javaFile);
+    changeSet.addedSources.add(source);
+    context.applyChanges(changeSet);
+    return source;
+  }
+}
+