dart2dart: Introduce Renamer that is used by renaming unparser

lib/compiler/implementation/dart_backend/renamer.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.
+
+/**
+ * Renames types, identifiers before printing them out.
+ */
+interface Renamer {

[Anton Muhin, 2012/07/23 11:23:10]

interfaces are going away, let's use just a single class Renamer (merging w/
ConflictingRenamer) and we'll split it back if need be later.

[Roman, 2012/07/23 15:34:15]

As discussed, created Renamer interface and NoRenamer to use in Node class
without any additional deps.

+  void setContext(Element element);
+
+  /**
+   * Renames type name for given type annotation.
+   * Should not touch type arguments.
+   */
+  String renameTypeName(TypeAnnotation type);
+
+  String renameType(Type type);
+
+  /**
+   * Renames method name.
+   */
+  String renameSendMethod(Send send);
+  String renameIdentifier(Identifier node);
+}
+
+/**
+ * Renames only top-level elements that would let to ambiguity if not renamed.
+ */
+class ConflictingRenamer implements Renamer {

[Anton Muhin, 2012/07/23 11:23:10]

Conflicting sounds weird, what do you try to convey?

[Roman, 2012/07/23 15:34:15]

That it renames only conflicting elements. I'm happy to change it to something
that sounds better.

+  final Compiler compiler;
+  Map<Element, String> renamed;

[Anton Muhin, 2012/07/23 11:23:10]

final?

[Roman, 2012/07/23 15:34:15]

Done.

+  Set<String> usedTopLevelIdentifiers;

[Anton Muhin, 2012/07/23 11:23:10]

final?

[Roman, 2012/07/23 15:34:15]

Done.

+  Map<Element, TreeElements> get resolvedElements() => compiler.enqueuer.resolution.resolvedElements;

[Anton Muhin, 2012/07/23 11:23:10]

nit: please, move getter below the fields proper and separate with a blank line

[Roman, 2012/07/23 15:34:15]

Done.

+  TreeElements contextElements;
+  Element context;
+
+  ConflictingRenamer(this.compiler) :
+      renamed = new Map<Element, String>(),
+      usedTopLevelIdentifiers = new Set<String>();
+
+  void setContext(Element element) {

[Anton Muhin, 2012/07/23 11:23:10]

I don't like this setContext thing, cannot we create a renamer for each context?

[Roman, 2012/07/23 15:34:15]

Unfortunately not. Renamer should have a state (like already renamed elements)
that lives as long as we're emitting dart code. Another possible solution is to
pass already renamed elements to Renamer constructor, but I don't like this
because this is about taking Renamer internals to outside.

+    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()) {

[Anton Muhin, 2012/07/23 11:23:10]

what about top-level variables?

[Roman, 2012/07/23 15:34:15]

I don't quite understand. What about them?

[Anton Muhin, 2012/07/23 17:01:27]

Shouldn't you rename them as well?

On 2012/07/23 15:34:15, Roman wrote:

+      return renameElement(contextElements[send]);
+    } else {
+      return null;
+    }
+  }
+
+  String renameTypeName(TypeAnnotation typeAnnotation) {
+    if (contextElements == null

[Anton Muhin, 2012/07/23 11:23:10]

nit: === null (here and below)

[Anton Muhin, 2012/07/23 11:23:10]

how contextElements can be null?

[Roman, 2012/07/23 15:34:15]

Done.

[Roman, 2012/07/23 15:34:15]

this happens for class member fields.

[Anton Muhin, 2012/07/23 17:01:27]

why?  and, please, assert.

[Roman, 2012/07/23 17:38:32]

I'm not sure why. Maybe resolver needs some fixes. Added a TODO.

+        || contextElements.getType(typeAnnotation) == null) {
+      // We have no info about this type from resolver.

[Anton Muhin, 2012/07/23 11:23:10]

when does it happen?

[Roman, 2012/07/23 15:34:15]

this happens for class member fields. Maybe it's a resolver problem, I added
TODO.

+      if (context.isField() && context.variables.computeType(compiler) !== null) {
+        // A field.
+        return renameType(context.variables.type);
+      } else {
+        return typeAnnotation.typeName.unparse();
+      }
+    }
+
+    Type type = contextElements.getType(typeAnnotation);
+    if (typeAnnotation.typeName is Send

[Anton Muhin, 2012/07/23 11:23:10]

what about generic types?

[Roman, 2012/07/23 15:34:15]

Generics are in type arguments. Here we care only about the "core" type.

[Anton Muhin, 2012/07/23 17:01:27]

Sorry, do you process generics correctly or not?

[Roman, 2012/07/23 17:38:33]

Yes. 

+        && typeAnnotation.typeName.receiver.source.slowToString() == type.name.slowToString()) {

[Anton Muhin, 2012/07/23 11:23:10]

what's the case when typeName is Send, but receiver.source != type.name?

[Roman, 2012/07/23 15:34:15]

For example when we have a method that returns "mylib.A" 

+      // Got factory invocation. Need to rename first part.
+      return "${renameType(type)}.${typeAnnotation.typeName.selector.source.slowToString()}";
+    }
+    String newName = renameType(type);

[Anton Muhin, 2012/07/23 11:23:10]

nit: no need in newName local.

[Roman, 2012/07/23 15:34:15]

Done.

+    return newName;
+  }
+
+  String renameType(Type type) {

[Anton Muhin, 2012/07/23 11:23:10]

nit: => renameElement(type.element);

[Roman, 2012/07/23 15:34:15]

Done.

+    Element typeElement = type.element;
+    return renameElement(typeElement);
+  }
+
+  String renameIdentifier(Identifier node) {
+    if (context.isGenerativeConstructor()) {
+      // This is either a factory constructor or simple one.
+      var enclosingClass = context.getEnclosingClass();
+      if (node.token.slowToString() == context.name.slowToString()

[Anton Muhin, 2012/07/23 11:23:10]

it looks like you duplicate a work of a resolver: this names equalities should
have been resolved, no?

[Roman, 2012/07/23 15:34:15]

Added TODO as above. I'll try to investigate if resolver can help us here as my
next task.

+          || enclosingClass.name.slowToString() == node.token.slowToString()) {
+        return renameElement(enclosingClass);
+      }
+    }
+    if (context.isFunction() && context.cachedNode.name == node) {
+      return renameElement(context);
+    }
+    return null;

[Anton Muhin, 2012/07/23 11:23:10]

again, what about top-level fields and privates?

[Roman, 2012/07/23 15:34:15]

Again please elaborate :)

[Anton Muhin, 2012/07/23 17:01:27]

:) I think we should rename both top level vars and private names.

On 2012/07/23 15:34:15, Roman wrote:

+  }
+
+  String renameElement(Element element) {
+    String originalName = element.name.slowToString();
+    if (element == null || element.getLibrary() == compiler.coreLibrary
+        || !element.isTopLevel()) {
+      return originalName;
+    }
+    if (renamed[element] !== null) {
+      return renamed[element];
+    }
+
+    // Not renamed and top element.
+    String name = originalName;
+    while (usedTopLevelIdentifiers.contains(name)) {
+      name = "_$name";
+    }
+    usedTopLevelIdentifiers.add(name);
+    renamed[element] = name;
+    return name;
+  }
+}