Track emitted classes in incremental compiler.

dart/pkg/compiler/lib/src/js_emitter/code_emitter_task.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 dart2js.js_emitter;
 
 const USE_NEW_EMITTER = const bool.fromEnvironment("dart2js.use.new.emitter");
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
@@ skipping 303 matching lines @@
   void computeNeededLibraries() {
     void addSurroundingLibraryToSet(Element element) {
       OutputUnit unit = compiler.deferredLoadTask.outputUnitForElement(element);
       LibraryElement library = element.library;
       outputLibraryLists.putIfAbsent(unit, () => new Set<LibraryElement>())
           .add(library);
     }
 
     backend.generatedCode.keys.forEach(addSurroundingLibraryToSet);
     neededClasses.forEach(addSurroundingLibraryToSet);
-}
+  }
+
+  void computeNeeds() {

[karlklose, 2014/12/01 10:13:31]

Perhaps you can find a better name than "needs". How about
"computeEntitiesToEmit"?

At least the, function should have a comment that describes what it is supposed
to compute.

[ahe, 2014/12/01 10:28:35]

Since most of the methods are called "computedNeededFoo", I think
computeNeed...something is a good fit.

How about: computeNeededEntities?
I'd rather not add documentation as I'm not 100% sure exactly what is computed.
Or I can add something vague like:

/// Initializes various collections that inform the emitter about what is
needed.

The reason why I'd rather not add documentation is that I'm not 100% sure that
everything that I think should be computed by this method is actually computed
by this method.

WDYT?

[ahe, 2014/12/01 13:58:52]

Discussed offline: I've renamed the method to computeAllNeededEntities.

+    // Compute the required type checks to know which classes need a
+    // 'is$' method.
+    typeTestEmitter.computeRequiredTypeChecks();
+
+    computeNeededDeclarations();
+    computeNeededConstants();
+    computeNeededStatics();
+    computeNeededLibraries();
+  }
 
   void assembleProgram() {
     measure(() {
       emitter.invalidateCaches();
 
-      // Compute the required type checks to know which classes need a
-      // 'is$' method.
-      typeTestEmitter.computeRequiredTypeChecks();
-
-      computeNeededDeclarations();
-      computeNeededConstants();
-      computeNeededStatics();
-      computeNeededLibraries();
-
+      computeNeeds();
 
       Program program;
       if (USE_NEW_EMITTER) {
         program = new ProgramBuilder(compiler, namer, this).buildProgram();
       }
       emitter.emitProgram(program);
     });
   }
 }
 
 abstract class Emitter {
   void emitProgram(Program program);
 
   jsAst.Expression generateEmbeddedGlobalAccess(String global);
   jsAst.Expression constantReference(ConstantValue value);
 
   int compareConstants(ConstantValue a, ConstantValue b);
   bool isConstantInlinedOrAlreadyEmitted(ConstantValue constant);
 
   void invalidateCaches();
 }