dart2js: Construct the entire output as a single AST before printing.

pkg/js_ast/lib/src/printer.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 js_ast;
 
 
 class JavaScriptPrintingOptions {
   final bool shouldCompressOutput;
   final bool minifyLocalVariables;
@@ skipping 1138 matching lines @@
 
   void forEach(void fun(T x)) {
     list.forEach(fun);
   }
 }
 
 // Collects all the var declarations in the function.  We need to do this in a
 // separate pass because JS vars are lifted to the top of the function.
 class VarCollector extends BaseVisitor {
   bool nested;
+  bool disableRenaming = false;

[floitsch, 2015/05/19 13:43:35]

change to "enableRenaming".

[herhut, 2015/05/19 14:08:09]

Done.

   final OrderedSet<String> vars;
   final OrderedSet<String> params;
 
+  static final String disableVariableMinificationPattern = "::norenaming::";
+  static final String enableVariableMinificationPattern = "::dorenaming::";
+
   VarCollector() : nested = false,
                    vars = new OrderedSet<String>(),
                    params = new OrderedSet<String>();
 
   void forEachVar(void fn(String v)) => vars.forEach(fn);
   void forEachParam(void fn(String p)) => params.forEach(fn);
 
   void collectVarsInFunction(Fun fun) {
     if (!nested) {
       nested = true;
@@ skipping 16 matching lines @@
     // Note that we don't bother collecting the name of the function.
     collectVarsInFunction(namedFunction.function);
   }
 
   void visitFun(Fun fun) {
     collectVarsInFunction(fun);
   }
 
   void visitThis(This node) {}
 
+  void visitComment(Comment node) {
+    if (node.comment.contains(disableVariableMinificationPattern)) {
+      disableRenaming = true;
+    } else if (node.comment.contains(enableVariableMinificationPattern)) {
+      disableRenaming = false;
+    }
+  }
+
   void visitVariableDeclaration(VariableDeclaration decl) {
-    if (decl.allowRename) vars.add(decl.name);
+    if (!disableRenaming && decl.allowRename) vars.add(decl.name);
   }
 }
 
 
 /**
  * Returns true, if the given node must be wrapped into braces when used
  * as then-statement in an [If] that has an else branch.
  */
 class DanglingElseVisitor extends BaseVisitor<bool> {
   JavaScriptPrintingContext context;
@@ skipping 203 matching lines @@
     }
   }
 
   EnterExitNode exitNode(JavaScriptPrintingContext context, int position) {
     // Enter must happen before exit.
     addToNode(context, position);
     context.exitNode(node, startPosition, position, closingPosition);
     return parent;
   }
 }