dart2dart introduce "emitter" that that generates source code.

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 DiagnosticListener listener;
+  final StringBuffer sb;
+
+  Emitter(this.listener) : sb = new StringBuffer();
+
+  /**
+   * Outputs given class element with selected inner elements.
+   */
+  void outputClass(ClassElement classElement, Set<Element> innerElements) {
+    // TODO(smok): Very soon properly print out correct class declaration with
+    // extends, implements, etc.
+    sb.add('class ');
+    sb.add(classElement.name.slowToString());
+    sb.add('{');
+    innerElements.forEach((element) {
+      // TODO(smok): Filter out default constructors here.
+      outputElement(element);
+    });
+    sb.add('}');
+  }
+
+  void outputElement(Element 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()) {
+      // Add modifiers first.
+      sb.add(element.modifiers.toString());
+      sb.add(' ');
+      // Figure out type.
+      if (element is VariableElement) {
+        VariableListElement variables = element.variables;
+        if (variables.type !== null) {
+          sb.add(variables.type);
+          sb.add(' ');
+        }
+      }
+      // TODO(smok): Maybe not rely on node unparsing,
+      // but unparse initializer manually.
+      sb.add(element.parseNode(listener).unparse());
+      sb.add(';');
+    } else {
+      if (element.isSetter()) {
+        sb.add('set ');
+      } else if (element.isGetter()) {
+        sb.add('get ');
+      }
+      sb.add(element.parseNode(listener).unparse());
+    }
+  }
+
+  String toString() => sb.toString();
+}