First end-to-end capability in analyzer2dart.

pkg/analyzer2dart/lib/src/tree_shaker.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.treeShaker;
 
 import 'dart:collection';
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:compiler/implementation/universe/universe.dart';
 
 import 'closed_world.dart';
 
 class TreeShaker {
   List<Element> _queue = <Element>[];
   Set<Element> _alreadyEnqueued = new HashSet<Element>();
-  ClosedWorld _world = new ClosedWorld();
+  ClosedWorld _world;
   Set<Selector> _selectors = new HashSet<Selector>();
 
+  TreeShaker(FunctionElement mainFunction)
+      : _world = new ClosedWorld(mainFunction) {
+    addElement(mainFunction);
+  }
+
   void addElement(Element element) {
     if (_alreadyEnqueued.add(element)) {
       _queue.add(element);
     }
   }
 
   void addSelector(Selector selector) {
     if (_selectors.add(selector)) {
       // New selector, so match it against all class methods.
       _world.instantiatedClasses.forEach((ClassElement element, AstNode node) {
@@ skipping 58 matching lines @@
         _world.fields[element] = declaration;
       } else {
         throw new Exception('Unexpected element type while tree shaking');
       }
     }
     print('Tree shaking done');
     return _world;
   }
 }
 
+Selector createSelectorFromMethodInvocation(MethodInvocation node) {
+  int arity = 0;
+  List<String> namedArguments = <String>[];
+  for (var x in node.argumentList.arguments) {
+    if (x is NamedExpression) {
+      namedArguments.add(x.name.label.name);
+    } else {
+      arity++;
+    }
+  }
+  return new Selector.call(node.methodName.name, null, arity, namedArguments);
+}
+
 class TreeShakingVisitor extends RecursiveAstVisitor {
   final TreeShaker treeShaker;
 
   TreeShakingVisitor(this.treeShaker);
 
   /**
    * Handle a true method call (a MethodInvocation that represents a call to
    * a non-static method).
    */
   void handleMethodCall(MethodInvocation node) {
-    int arity = 0;
-    List<String> namedArguments = <String>[];
-    for (var x in node.argumentList.arguments) {
-      if (x is NamedExpression) {
-        namedArguments.add(x.name.label.name);
-      } else {
-        arity++;
-      }
-    }
-    treeShaker.addSelector(
-        new Selector.call(node.methodName.name, null, arity, namedArguments));
+    treeShaker.addSelector(createSelectorFromMethodInvocation(node));
   }
 
   @override
   void visitFunctionDeclaration(FunctionDeclaration node) {
     super.visitFunctionDeclaration(node);
   }
 
   @override
   void visitInstanceCreationExpression(InstanceCreationExpression node) {
     ConstructorElement staticElement = node.staticElement;
@@ skipping 112 matching lines @@
     //   main() {
     //     new A().g;
     //   }
     // TODO(paulberry): do setters go through this path as well?
     // TODO(paulberry): handle cases where the property access is represented
     // as a PrefixedIdentifier.
     super.visitPropertyAccess(node);
     treeShaker.addSelector(new Selector.getter(node.propertyName.name, null));
   }
 }