A visitor that builds a map from node to "Usage".

lib/compiler/implementation/dart_backend/emitter.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.
 
 /**
  * Dart backend helper for converting program IR back to source code.
  */
 class Emitter {
 
   final Compiler compiler;
   final StringBuffer sb;
   final ConflictingRenamer renamer;
   final Set<VariableListElement> processedVariableLists;
 
-  Emitter(Compiler compiler) :
-      this.compiler = compiler,
+  Emitter(this.compiler, this.renamer) :
       sb = new StringBuffer(),
-      renamer = new ConflictingRenamer(compiler),
       processedVariableLists = new Set<VariableListElement>();
 
   /**
    * Outputs given class element with selected inner elements.
    */
   void outputClass(ClassElement classElement, Set<Element> innerElements) {
     Unparser unparser = new Unparser(renamer);
     ClassNode classNode = classElement.parseNode(compiler);
     // classElement.beginToken is 'class', 'interface', or 'abstract'.
     sb.add(classElement.beginToken.slowToString());
     if (classElement.beginToken.slowToString() == 'abstract') {
       sb.add(' ');
       sb.add(classElement.beginToken.next.slowToString());  // 'class'
     }
     sb.add(' ');
     sb.add(renamer.renameElement(classElement));
     if (classNode.typeParameters !== null) {
       sb.add(unparser.unparse(classNode.typeParameters));
     }
-    renamer.setContext(classElement);
     if (classNode.extendsKeyword !== null) {
       sb.add(' ');
       classNode.extendsKeyword.value.printOn(sb);
       sb.add(' ');
       sb.add(unparser.unparse(classNode.superclass));
     }
     if (!classNode.interfaces.isEmpty()) {
       sb.add(' ');
       sb.add(unparser.unparse(classNode.interfaces));
     }
     if (classNode.defaultClause !== null) {
       sb.add(' default ');
       sb.add(unparser.unparse(classNode.defaultClause));
     }
     sb.add('{');
     innerElements.forEach((element) {
       // TODO(smok): Filter out default constructors here.
       outputElement(element);
     });
     sb.add('}');
   }
 
   void outputElement(Element element) {
     Unparser unparser = new Unparser(renamer);
-    renamer.setContext(element);
     // TODO(smok): Figure out why AbstractFieldElement appears here,
     // we have used getters/setters resolved instead of it.
     if (element is SynthesizedConstructorElement
         || element is AbstractFieldElement) return;
     if (element.isField()) {
       assert(element is VariableElement);
       // Different VariableElement's may refer to the same VariableListElement.
       // Output this list only once.
       // TODO: only emit used variables.
       final variableList = element.variables;
@@ skipping 16 matching lines @@
       if (!uri.startsWith('dart:')) continue;
       final lib = libraries[uri];
       if (renamer.imports.containsKey(lib)) {
         result.add('#import("$uri", prefix: "${renamer.imports[lib]}");');
       }
     }
     result.add(sb);
     return result.toString();
   }
 }