Refactor and simplify the dart2dart renamer.

sdk/lib/_internal/compiler/implementation/dart_backend/backend.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.
 
 part of dart_backend;
 
 // TODO(ahe): This class is simply wrong.  This backend should use
 // elements when it can, not AST nodes.  Perhaps a [Map<Element,
 // TreeElements>] is what is needed.
 class ElementAst {
   final Node ast;
   final TreeElements treeElements;
 
   ElementAst(AstElement element)
       : this.internal(element.resolvedAst.node, element.resolvedAst.elements);
 
   ElementAst.internal(this.ast, this.treeElements);
 }
 
 class DartBackend extends Backend {
   final List<CompilerTask> tasks;
   final bool forceStripTypes;
   final bool stripAsserts;
   // TODO(antonm): make available from command-line options.
   final bool outputAst = false;
-  final Map<Node, String> renames;
-  final Map<LibraryElement, String> imports;
   final Map<ClassNode, List<Node>> memberNodes;
-  Map<Element, LibraryElement> reexportingLibraries;
+
+  PlaceholderRenamer placeholderRenamer;
 
   // TODO(zarah) Maybe change this to a command-line option.
   // Right now, it is set by the tests.
   bool useMirrorHelperLibrary = false;
 
   /// Initialized if the useMirrorHelperLibrary field is set.
   MirrorRenamer mirrorRenamer;
 
   /// Initialized when dart:mirrors is loaded if the useMirrorHelperLibrary
   /// field is set.
@@ skipping 58 matching lines @@
         if (element.allSupertypes != null) {
           element.allSupertypes.forEach(workQueue.add);
         }
       }
     }
     return true;
   }
 
   DartBackend(Compiler compiler, List<String> strips)
       : tasks = <CompilerTask>[],
-        renames = new Map<Node, String>(),
-        imports = new Map<LibraryElement, String>(),
         memberNodes = new Map<ClassNode, List<Node>>(),
-        reexportingLibraries = <Element, LibraryElement>{},
         forceStripTypes = strips.indexOf('types') != -1,
         stripAsserts = strips.indexOf('asserts') != -1,
         constantCompilerTask  = new DartConstantTask(compiler),
         super(compiler) {
     resolutionCallbacks = new DartResolutionCallbacks(this);
   }
 
   bool classNeedsRti(ClassElement cls) => false;
   bool methodNeedsRti(FunctionElement function) => false;
 
@@ skipping 30 matching lines @@
             element is !AbstractFieldElement)
         || element.library == mirrorHelperLibrary;
   }
 
   void assembleProgram() {
     // Conservatively traverse all platform libraries and collect member names.
     // TODO(antonm): ideally we should only collect names of used members,
     // however as of today there are problems with names of some core library
     // interfaces, most probably for interfaces of literals.
     final fixedMemberNames = new Set<String>();
+
+    Map<Element, LibraryElement> reexportingLibraries =
+        <Element, LibraryElement>{};
+
     for (final library in compiler.libraryLoader.libraries) {
       if (!library.isPlatformLibrary) continue;
       library.forEachLocalMember((Element element) {
         if (element.isClass) {
           ClassElement classElement = element;
           assert(invariant(classElement, classElement.isResolved,
               message: "Unresolved platform class."));
           classElement.forEachLocalMember((member) {
             final name = member.name;
             // Skip operator names.
             if (!name.startsWith(r'operator$')) {
               // Fetch name of named constructors and factories if any,
               // otherwise store regular name.
               // TODO(antonm): better way to analyze the name.
               fixedMemberNames.add(name.split(r'$').last);
             }
           });
         }
         // Even class names are added due to a delicate problem we have:
         // if one imports dart:core with a prefix, we cannot tell prefix.name
         // from dynamic invocation (alas!).  So we'd better err on preserving
         // those names.
         fixedMemberNames.add(element.name);
       });
+
       for (Element export in library.exports) {
         if (!library.isInternalLibrary &&
             export.library.isInternalLibrary) {
           // If an element of an internal library is reexported by a platform
           // library, we have to import the reexporting library instead of the
           // internal library, because the internal library is an
           // implementation detail of dart2js.
           reexportingLibraries[export] = library;
         }
       }
@@ skipping 195 matching lines @@
 
       if (element.isClass) {
         classMembers[element].forEach(makePlaceholders);
       }
     }
     topLevelElements.forEach(makePlaceholders);
     // Create renames.
     bool shouldCutDeclarationTypes = forceStripTypes
         || (compiler.enableMinification
             && isSafeToRemoveTypeDeclarations(classMembers));
-    renamePlaceholders(
-        compiler, collector, renames, imports,
-        fixedMemberNames, reexportingLibraries,
-        shouldCutDeclarationTypes,
-        uniqueGlobalNaming: useMirrorHelperLibrary);
+
+    placeholderRenamer =
+        new PlaceholderRenamer(compiler, fixedMemberNames, reexportingLibraries,
+            cutDeclarationTypes: shouldCutDeclarationTypes);
+
+    placeholderRenamer.computeRenames(collector);
 
     // Sort elements.
-    final sortedTopLevels = sortElements(topLevelElements);
-    final sortedClassMembers = new Map<ClassElement, List<Element>>();
+    final List<Element> sortedTopLevels = sortElements(topLevelElements);
+    final Map<ClassElement, List<Element>> sortedClassMembers =
+        new Map<ClassElement, List<Element>>();
     classMembers.forEach((classElement, members) {
       sortedClassMembers[classElement] = sortElements(members);
     });
 
     if (outputAst) {
       // TODO(antonm): Ideally XML should be a separate backend.
       // TODO(antonm): obey renames and minification, at least as an option.
       StringBuffer sb = new StringBuffer();
       outputElement(element) {
         sb.write(element.parseNode(compiler).toDebugString());
       }
 
       // Emit XML for AST instead of the program.
       for (final topLevel in sortedTopLevels) {
         if (topLevel.isClass && !emitNoMembersFor.contains(topLevel)) {
           // TODO(antonm): add some class info.
           sortedClassMembers[topLevel].forEach(outputElement);
         } else {
           outputElement(topLevel);
         }
       }
       compiler.assembledCode = '<Program>\n$sb</Program>\n';
       return;
     }
 
-    final topLevelNodes = <Node>[];
+    final List<Node> topLevelNodes = <Node>[];
     for (final element in sortedTopLevels) {
       topLevelNodes.add(elementAsts[element].ast);
       if (element.isClass && !element.isMixinApplication) {
         final members = <Node>[];
         for (final member in sortedClassMembers[element]) {
           members.add(elementAsts[member].ast);
         }
         memberNodes[elementAsts[element].ast] = members;
       }
     }
 
     if (useMirrorHelperLibrary) {
-      mirrorRenamer.addRenames(renames, topLevelNodes, collector);
+      mirrorRenamer.addRenames(placeholderRenamer.renames,
+                               topLevelNodes, collector);
     }
 
-    final unparser = new EmitterUnparser(renames, stripTypes: forceStripTypes,
-        minify: compiler.enableMinification);
-    emitCode(unparser, imports, topLevelNodes, memberNodes);
-    String assembledCode = unparser.result;
-    compiler.outputProvider('', 'dart')
-        ..add(assembledCode)
-        ..close();
-    compiler.assembledCode = assembledCode;
+    final EmitterUnparser unparser =
+        new EmitterUnparser(placeholderRenamer.renames,
+                            stripTypes: forceStripTypes,
+                            minify: compiler.enableMinification);
+    for (LibraryElement library in placeholderRenamer.platformImports) {
+      if (library.isPlatformLibrary && !library.isInternalLibrary) {
+        unparser.unparseImportTag(library.canonicalUri.toString());
+      }
+    }
+    for (int i = 0; i < sortedTopLevels.length; i++) {
+      Element element = sortedTopLevels[i];
+      Node node = topLevelNodes[i];
+      if (node is ClassNode) {
+        // TODO(smok): Filter out default constructors here.
+        unparser.unparseClassWithBody(node, memberNodes[node]);
+      } else {
+        unparser.unparse(node);
+      }
+      unparser.newline();
+    }
 
+    compiler.assembledCode = unparser.result;
+    compiler.outputProvider("", "dart")
+         ..add(compiler.assembledCode)
+         ..close();
     // Output verbose info about size ratio of resulting bundle to all
     // referenced non-platform sources.
     logResultBundleSizeInfo(topLevelElements);
   }
 
   void logResultBundleSizeInfo(Set<Element> topLevelElements) {
     Iterable<LibraryElement> referencedLibraries =
         compiler.libraryLoader.libraries.where(isUserLibrary);
     // Sum total size of scripts in each referenced library.
     int nonPlatformSize = 0;
@@ skipping 204 matching lines @@
   }
 
   Constant compileMetadata(MetadataAnnotation metadata,
                            Node node,
                            TreeElements elements) {
     return measure(() {
       return constantCompiler.compileMetadata(metadata, node, elements);
     });
   }
 }