Add HasSubclasses function to class hierarchy analysis.

runtime/vm/class_table.cc

 // 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.
 
 #include "vm/class_table.h"
 #include "vm/flags.h"
 #include "vm/freelist.h"
 #include "vm/object.h"
 #include "vm/raw_object.h"
 #include "vm/visitor.h"
@@ skipping 79 matching lines @@
   for (intptr_t i = 1; i < top_; i++) {
     cls = At(i);
     if (cls.raw() != reinterpret_cast<RawClass*>(0)) {
       name = cls.Name();
       OS::Print("%d: %s\n", i, name.ToCString());
     }
   }
 }
 
 
+bool ClassTable::HasSubclasses(intptr_t cid) const {

[Ivan Posva, 2012/08/21 03:01:27]

This API has nothing to do with ClassTable, please remove it from here or
explain the tie in to the functionality of ClassTable which maps cids to
classes.

+  const Class& cls = Class::Handle(At(cid));
+  ASSERT(!cls.IsNull());
+  // TODO(regis): Replace assert below with ASSERT(cid > kDartObjectCid).
+  ASSERT(!cls.IsObjectClass());
+  const GrowableObjectArray& cls_direct_subclasses =
+      GrowableObjectArray::Handle(cls.direct_subclasses());
+  return
+      !cls_direct_subclasses.IsNull() && (cls_direct_subclasses.Length() > 0);
+}
+
+
 // Returns true if the given array of cids contains the given cid.
 static bool ContainsCid(ZoneGrowableArray<intptr_t>* cids, intptr_t cid) {
   for (intptr_t i = 0; i < cids->length(); i++) {
     if ((*cids)[i] == cid) {
       return true;
     }
   }
   return false;
 }
 
@@ skipping 55 matching lines @@
   ASSERT(!function.IsNull());
   ASSERT(function.IsDynamicFunction());
   const Class& function_owner = Class::Handle(function.Owner());
   const String& function_name = String::Handle(function.name());
   ZoneGrowableArray<intptr_t>* cids = new ZoneGrowableArray<intptr_t>();
   CollectSubclassIds(cids, function_owner);
   return GetNamedInstanceFunctionsOf(*cids, function_name);
 }
 
 }  // namespace dart