dart2dart: Introduce Renamer that is used by renaming unparser

lib/compiler/implementation/dart_backend/renamer.dart

Index: lib/compiler/implementation/dart_backend/renamer.dart
diff --git a/lib/compiler/implementation/dart_backend/renamer.dart b/lib/compiler/implementation/dart_backend/renamer.dart
new file mode 100644
index 0000000000000000000000000000000000000000..da1bd9f59aacba0037408ff13a2d6ba599a10a91
--- /dev/null
+++ b/lib/compiler/implementation/dart_backend/renamer.dart
@@ -0,0 +1,104 @@
+// 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.
+
+/**
+ * Renames only top-level elements that would let to ambiguity if not renamed.
+ * TODO(smok): Make sure that top-level fields and methods correctly renamed.
+ */
+class ConflictingRenamer extends Renamer {
+  final Compiler compiler;
+  final Map<Element, String> renamed;
+  final Set<String> usedTopLevelIdentifiers;
+  TreeElements contextElements;
+  Element context;
+
+  Map<Element, TreeElements> get resolvedElements() =>
+      compiler.enqueuer.resolution.resolvedElements;
+
+  ConflictingRenamer(this.compiler) :
+      renamed = new Map<Element, String>(),
+      usedTopLevelIdentifiers = new Set<String>();
+
+  void setContext(Element element) {
+    this.context = element;
+    contextElements = resolvedElements[element];
+  }
+
+  String renameSendMethod(Send send) {
+    // Rename only if this Send is a function call.
+    if (contextElements[send] !== null && contextElements[send].isFunction()) {
+      return renameElement(contextElements[send]);
+    } else {
+      return null;
+    }
+  }
+
+  String renameTypeName(TypeAnnotation typeAnnotation) {
+    if (contextElements === null
+        || contextElements.getType(typeAnnotation) === null) {
+      // We have no info about this type from resolver.
+      // This happens for class member fields.
+      // TODO(smok): Maybe resolver should have this information, fix if so.
+      if (context.isField()
+          && context.variables.computeType(compiler) !== null) {
+        // A field.
+        return renameType(context.variables.type);
+      } else {
+        return typeAnnotation.typeName.unparse();
+      }
+    }
+
+    // TODO(smok): Check if resolver can help us identifying factory
+    // constructors.
+    Type type = contextElements.getType(typeAnnotation);
+    if (typeAnnotation.typeName is Send
+        && typeAnnotation.typeName.receiver.source.slowToString() 
+            == type.name.slowToString()) {
+      // Got factory invocation. Need to rename first part.
+      return "${renameType(type)}."
+          "${typeAnnotation.typeName.selector.source.slowToString()}";
+    }
+    return renameType(type);
+  }
+
+  String renameType(Type type) => renameElement(type.element);
+
+  String renameIdentifier(Identifier node) {
+    if (context.isGenerativeConstructor()) {
+      // This is either a factory constructor or simple one.
+      // TODO(smok): Check if resolver can help us identifying factory
+      // constructors.
+      var enclosingClass = context.getEnclosingClass();
+      if (node.token.slowToString() == context.name.slowToString()
+          || enclosingClass.name.slowToString() == node.token.slowToString()) {
+        return renameElement(enclosingClass);
+      }
+    }
+    if (context.isFunction() && context.cachedNode.name == node) {
+      return renameElement(context);
+    }
+    return null;
+  }
+
+  String renameElement(Element element) {
+    String originalName = element.name.slowToString();
+    if (element.getLibrary() == compiler.coreLibrary || !element.isTopLevel()) {
+      return originalName;
+    }
+    if (renamed[element] !== null) {
+      return renamed[element];
+    }
+
+    // Not renamed and top element.
+    // TODO(smok): Make sure that the new name does not conflict with existing
+    // local identifiers.
+    String name = originalName;
+    while (usedTopLevelIdentifiers.contains(name)) {
+      name = "_$name";
+    }
+    usedTopLevelIdentifiers.add(name);
+    renamed[element] = name;
+    return name;
+  }
+}