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

lib/compiler/implementation/dart_backend/usager.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.
+
+class SendVisitor extends ResolvedVisitor<String> {
+  final Usager usager;
+
+  SendVisitor(this.usager, TreeElements elements) : super(elements);
+
+  R visitSuperSend(Send node) => node.visitChildren(usager);
+  R visitOperatorSend(Send node) => node.visitChildren(usager);
+  R visitClosureSend(Send node) => node.visitChildren(usager);
+  R visitDynamicSend(Send node) => node.visitChildren(usager);
+  R visitForeignSend(Send node) => node.visitChildren(usager);
+
+  R visitGetterSend(Send node) {
+    final element = elements[node];
+    if (element !== null && element.isTopLevel()) {

[Anton Muhin, 2012/08/07 12:32:11]

maybe use early return: if (element === null || element.isTopLevel()) {
  node.visitChildren(usager);
  return;
}

[Roman, 2012/08/07 15:44:03]

Done.

+      if (node.receiver !== null) {
+        // Library reference prefix. Omit it.

[Anton Muhin, 2012/08/07 12:32:11]

please, add an assert, that receiver resolves to prefix:
assert(elements[node.receover].isPrefix())

[Roman, 2012/08/07 15:44:03]

Done.

+        usager.useNull(node.receiver);
+      }
+      usager.useElement(node.selector, element);
+      usager.visit(node.argumentsNode);

[Anton Muhin, 2012/08/07 12:32:11]

I am not quite happy we duplicate visitChildren here: if somebody updates it,
we're in trouble

[Roman, 2012/08/07 15:44:03]

Changed to visitChildren, it should not matter much here.

+    } else {
+      node.visitChildren(usager);
+    }
+  }
+
+  R visitStaticSend(Send node) {

[Anton Muhin, 2012/08/07 12:32:11]

isn't that too complicated?

e.g. shouldn't we rename elements being output immediately, w/o resorting to the
things below?

[Roman, 2012/08/07 15:44:03]

I will use magic from your CL to make it better.

+    final element = elements[node];
+    if (element.isTopLevel()) {
+      if (node.receiver !== null) {
+        // Library reference prefix. Omit it.
+        usager.useNull(node.receiver);
+      }
+      usager.useMethod(node.selector, element);
+      usager.visit(node.argumentsNode);
+    } else if (
+        (element.isGenerativeConstructor() || element.isFactoryConstructor())
+        // Don't want to rename redirects to :this(args) or super calls.
+        && !Initializers.isConstructorRedirect(node)
+        && !Initializers.isSuperConstructorCall(node)) {
+      final FunctionElement constructor = element.asFunctionElement();
+      final Send nameAsSend = constructor.cachedNode.name.asSend();
+      if (nameAsSend !== null) {
+        // Named constructor or factory call.
+        if (node.selector is TypeAnnotation) {
+          // Simple A.fromFoo();
+          assert(node.selector.typeName is Send);
+          assert(node.selector.typeName.receiver is Identifier);
+          assert(node.selector.typeName.selector is Identifier);
+          usager.useType(node.selector.typeName.receiver,
+              usager.resolveType(node.selector));
+          usager.useConstructorName(
+              node.selector.typeName.selector, constructor);
+        } else {
+          // lib.A.fromFoo() or A<T>.fromFoo()
+          // or lib.A.fromFoo() or lib.A<T>.fromFoo();
+          assert(node.selector is Send);
+          assert(node.selector.selector is Identifier);
+          assert(node.selector.receiver is TypeAnnotation);
+          usager.useType(node.selector.receiver.typeName,
+              usager.resolveType(node.selector.receiver));
+          usager.useConstructorName(node.selector.selector, constructor);
+          usager.visit(node.selector.receiver.typeArguments);
+        }
+      } else {
+        // Ordinary constructor call.
+        assert(node.selector is TypeAnnotation);
+        usager.useType(
+            node.selector.typeName, usager.resolveType(node.selector));
+        usager.visit(node.selector.typeArguments);
+      }
+    } else {
+      // Fallback to default processing.
+      node.visitChildren(usager);
+    }
+  }
+}
+
+class Usager implements Visitor {
+  final Compiler compiler;
+  final Map<Node, Usage> usages;
+  Element currentElement;
+  TreeElements treeElements;
+
+  Usager(this.compiler) : usages = new Map<Node, Usage>();
+
+  /**
+   * Checks if [:libraryElement:] is a core lib, that is a library
+   * provided by the implementation like dart:core, dart:coreimpl, etc.
+   */
+  bool isDartCoreLib(Compiler compiler, LibraryElement libraryElement) {
+    final libraries = compiler.libraries;
+    for (final uri in libraries.getKeys()) {
+      if (libraryElement === libraries[uri]) {
+        if (uri.startsWith('dart:')) return true;
+      }
+    }
+    return false;
+  }
+
+  void process(Element element, TreeElements elements) {
+    currentElement = element;
+    treeElements = elements;
+    Node elementNode = element.parseNode(compiler);
+    elementNode.accept(this);
+  }
+
+  Type resolveType(TypeAnnotation typeAnnotation) {
+    if (treeElements === null) return null;
+    var result = treeElements.getType(typeAnnotation);
+    if (result == null) {

[Anton Muhin, 2012/08/07 12:32:11]

nit: === null

[Roman, 2012/08/07 15:44:03]

Done.

+      result = compiler.resolveTypeAnnotation(currentElement, typeAnnotation);
+    }
+    return result;
+  }
+
+  void useType(Node node, Type type) {
+    assert(type !== null);
+    usages[node] = new TypeUsage(type);
+  }
+  void useConstructorName(Identifier node, FunctionElement constructor) {
+    assert(constructor !== null);
+    usages[node] = new ConstructorNameUsage(constructor);
+  }
+  void useMethod(Node node, Element method) {
+    assert(method !== null);
+    assert(method is FunctionElement || method is VariableElement);
+    usages[node] = new MethodUsage(method);
+  }
+  void useNull(Node node) {
+    usages[node] = new NullUsage();
+  }
+  void useElement(Node node, Element element) {
+    assert(element !== null);
+    usages[node] = new ElementUsage(element);
+  }
+
+  void internalError(String reason, [Node node]) {
+    compiler.cancel(reason: reason, node: node);
+  }
+
+  R visit(Node node) => (node == null) ? null : node.accept(this);

[Anton Muhin, 2012/08/07 12:32:11]

nit: === null

[Roman, 2012/08/07 15:44:03]

Done.

+
+  R visitBlock(Block node) {

[Anton Muhin, 2012/08/07 12:32:11]

arrow syntax, your variant returns null.

[Anton Muhin, 2012/08/07 12:32:11]

cannot you reuse AbstractVisitor?

+    node.visitChildren(this);
+  }
+  R visitBreakStatement(BreakStatement node) {
+    node.visitChildren(this);
+  }
+  R visitCascade(Cascade node) {
+    node.visitChildren(this);
+  }
+  R visitCascadeReceiver(CascadeReceiver node) {
+    node.visitChildren(this);
+  }
+  R visitCaseMatch(CaseMatch node) {
+    node.visitChildren(this);
+  }
+  R visitCatchBlock(CatchBlock node) {
+    node.visitChildren(this);
+  }
+  R visitClassNode(ClassNode node) {
+    internalError('Should never meet ClassNode', node);
+  }
+  R visitConditional(Conditional node) {
+    node.visitChildren(this);
+  }
+  R visitContinueStatement(ContinueStatement node) {
+    node.visitChildren(this);
+  }
+  R visitDoWhile(DoWhile node) {
+    node.visitChildren(this);
+  }
+  R visitEmptyStatement(EmptyStatement node) {
+    node.visitChildren(this);
+  }
+  R visitExpressionStatement(ExpressionStatement node) {
+    node.visitChildren(this);
+  }
+  R visitFor(For node) {
+    node.visitChildren(this);
+  }
+  R visitForIn(ForIn node) {
+    node.visitChildren(this);
+  }
+  R visitFunctionDeclaration(FunctionDeclaration node) {
+    node.visitChildren(this);
+  }
+  R visitFunctionExpression(FunctionExpression node) {
+    node.visitChildren(this);
+  }
+  R visitIdentifier(Identifier node) {
+    if (currentElement.isGenerativeConstructor()
+        || currentElement.isFactoryConstructor()) {
+      // Two complicated cases for class/interface renaming:
+      // 1) class which implements constructors of other interfaces, but not
+      //    implements interfaces themselves:
+      //      0.dart: class C { I(); }
+      //      1.dart and 2.dart: interface I default C { I(); }
+      //    now we have to duplicate our I() constructor in C class with
+      //    proper names.
+      // 2) (even worse for us):
+      //      0.dart: class C { C(); }
+      //      1.dart: interface C default p0.C { C(); }
+      //    the second case is just a bug now.
+      final ClassElement enclosingClass = currentElement.getEnclosingClass();
+      if (node.token.slowToString() == enclosingClass.name.slowToString()) {
+        // TODO: distinguish the case of constructor vs. nested named closure
+        // (see function_syntax_test).
+        // TODO: fix the bugs above and turn if into the assert.
+        useType(node, enclosingClass.type);
+      }
+    } else if (currentElement.isFunction()
+        && currentElement.cachedNode.name == node) {
+      useMethod(node, currentElement);
+    }
+  }
+  R visitIf(If node) {
+    node.visitChildren(this);
+  }
+  R visitLabel(Label node) {
+    node.visitChildren(this);
+  }
+  R visitLabeledStatement(LabeledStatement node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralBool(LiteralBool node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralDouble(LiteralDouble node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralInt(LiteralInt node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralList(LiteralList node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralMap(LiteralMap node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralMapEntry(LiteralMapEntry node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralNull(LiteralNull node) {
+    node.visitChildren(this);
+  }
+  R visitLiteralString(LiteralString node) {
+    node.visitChildren(this);
+  }
+  R visitModifiers(Modifiers node) {
+    node.visitChildren(this);
+  }
+  R visitNamedArgument(NamedArgument node) {
+    node.visitChildren(this);
+  }
+  R visitNewExpression(NewExpression node) {
+    node.visitChildren(this);
+  }
+  R visitNodeList(NodeList node) {
+    node.visitChildren(this);
+  }
+  R visitOperator(Operator node) {
+    node.visitChildren(this);
+  }
+  R visitParenthesizedExpression(ParenthesizedExpression node) {
+    node.visitChildren(this);
+  }
+  R visitReturn(Return node) {
+    node.visitChildren(this);
+  }
+  R visitScriptTag(ScriptTag node) {
+    node.visitChildren(this);
+  }
+  R visitSend(Send send) => new SendVisitor(this, treeElements).visitSend(send);
+  R visitSendSet(SendSet node) {
+    node.visitChildren(this);
+  }
+  R visitStringInterpolation(StringInterpolation node) {
+    node.visitChildren(this);
+  }
+  R visitStringInterpolationPart(StringInterpolationPart node) {
+    node.visitChildren(this);
+  }
+  R visitStringJuxtaposition(StringJuxtaposition node) {
+    node.visitChildren(this);
+  }
+  R visitSwitchCase(SwitchCase node) {
+    node.visitChildren(this);
+  }
+  R visitSwitchStatement(SwitchStatement node) {
+    node.visitChildren(this);
+  }
+  R visitThrow(Throw node) {
+    node.visitChildren(this);
+  }
+  R visitTryStatement(TryStatement node) {
+    node.visitChildren(this);
+  }
+
+  R visitTypeAnnotation(TypeAnnotation node) {
+    Type type = resolveType(node);
+    useType(node.typeName, type);
+    visit(node.typeArguments);
+  }
+
+  R visitTypedef(Typedef node) {
+    node.visitChildren(this);
+  }
+  R visitTypeVariable(TypeVariable node) {
+    node.visitChildren(this);
+  }
+  R visitVariableDefinitions(VariableDefinitions node) {
+    node.visitChildren(this);
+  }
+  R visitWhile(While node) {
+    node.visitChildren(this);
+  }
+}