Issue 2081: Expose function's (closure's) inner context in debugger.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 10997 matching lines @@
   // Fill all context locals.
   if (!CopyContextLocalsToScopeObject(
           isolate, scope_info, context, module_scope)) {
     return Handle<JSObject>();
   }
 
   return module_scope;
 }
 
 
-// Iterate over the actual scopes visible from a stack frame. The iteration
-// proceeds from the innermost visible nested scope outwards. All scopes are
-// backed by an actual context except the local scope, which is inserted
-// "artificially" in the context chain.
+// Iterate over the actual scopes visible from a stack frame or from a closure.
+// The iteration proceeds from the innermost visible nested scope outwards.
+// All scopes are backed by an actual context except the local scope,
+// which is inserted "artificially" in the context chain.
 class ScopeIterator {
  public:
   enum ScopeType {
     ScopeTypeGlobal = 0,
     ScopeTypeLocal,
     ScopeTypeWith,
     ScopeTypeClosure,
     ScopeTypeCatch,
     ScopeTypeBlock,
     ScopeTypeModule
@@ skipping 80 matching lines @@
         // A failed reparse indicates that the preparser has diverged from the
         // parser or that the preparse data given to the initial parse has been
         // faulty. We fail in debug mode but in release mode we only provide the
         // information we get from the context chain but nothing about
         // completely stack allocated scopes or stack allocated locals.
         UNREACHABLE();
       }
     }
   }
 
+  ScopeIterator(Isolate* isolate,
+                Handle<JSFunction> function)
+    : isolate_(isolate),
+      frame_(NULL),
+      inlined_jsframe_index_(0),
+      function_(function),
+      context_(function->context()) {
+    if (function->IsBuiltin()) {
+      context_ = Handle<Context>();
+    }
+  }
+
   // More scopes?
   bool Done() { return context_.is_null(); }
 
   // Move to the next scope.
   void Next() {
     ScopeType scope_type = Type();
     if (scope_type == ScopeTypeGlobal) {
       // The global scope is always the last in the chain.
       ASSERT(context_->IsGlobalContext());
       context_ = Handle<Context>();
@@ skipping 200 matching lines @@
   }
 
   return Smi::FromInt(n);
 }
 
 
 static const int kScopeDetailsTypeIndex = 0;
 static const int kScopeDetailsObjectIndex = 1;
 static const int kScopeDetailsSize = 2;
 
+
+static MaybeObject* MaterializeScopeDetails(Isolate* isolate,
+    ScopeIterator* it) {
+  // Calculate the size of the result.
+  int details_size = kScopeDetailsSize;
+  Handle<FixedArray> details = isolate->factory()->NewFixedArray(details_size);
+
+  // Fill in scope details.
+  details->set(kScopeDetailsTypeIndex, Smi::FromInt(it->Type()));
+  Handle<JSObject> scope_object = it->ScopeObject();
+  RETURN_IF_EMPTY_HANDLE(isolate, scope_object);
+  details->set(kScopeDetailsObjectIndex, *scope_object);
+
+  return *isolate->factory()->NewJSArrayWithElements(details);
+}
+
 // Return an array with scope details
 // args[0]: number: break id
 // args[1]: number: frame index
 // args[2]: number: inlined frame index
 // args[3]: number: scope index
 //
 // The array returned contains the following information:
 // 0: Scope type
 // 1: Scope object
 RUNTIME_FUNCTION(MaybeObject*, Runtime_GetScopeDetails) {
@@ skipping 17 matching lines @@
 
   // Find the requested scope.
   int n = 0;
   ScopeIterator it(isolate, frame, inlined_jsframe_index);
   for (; !it.Done() && n < index; it.Next()) {
     n++;
   }
   if (it.Done()) {
     return isolate->heap()->undefined_value();
   }
+  return MaterializeScopeDetails(isolate, &it);
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_GetFunctionScopeCount) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 1);
+
+  // Check arguments.
+  CONVERT_ARG_HANDLE_CHECKED(JSFunction, fun, 0);
+
+  // Count the visible scopes.
+  int n = 0;
+  for (ScopeIterator it(isolate, fun);

[ulan, 2012/04/25 14:14:55]

This fits in one line.

[Peter Rybin, 2012/04/25 22:56:49]

Done.

+       !it.Done();
+       it.Next()) {
+    n++;
+  }
+
+  return Smi::FromInt(n);
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_GetFunctionScopeDetails) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 2);
+
+  // Check arguments.
+  CONVERT_ARG_HANDLE_CHECKED(JSFunction, fun, 0);
+  CONVERT_NUMBER_CHECKED(int, index, Int32, args[1]);
+
+  // Find the requested scope.
+  int n = 0;
+  ScopeIterator it(isolate, fun);
+  for (; !it.Done() && n < index; it.Next()) {
+    n++;
+  }
+  if (it.Done()) {
+    return isolate->heap()->undefined_value();
+  }
 
-  // Calculate the size of the result.
-  int details_size = kScopeDetailsSize;
-  Handle<FixedArray> details = isolate->factory()->NewFixedArray(details_size);
-
-  // Fill in scope details.
-  details->set(kScopeDetailsTypeIndex, Smi::FromInt(it.Type()));
-  Handle<JSObject> scope_object = it.ScopeObject();
-  RETURN_IF_EMPTY_HANDLE(isolate, scope_object);
-  details->set(kScopeDetailsObjectIndex, *scope_object);
-
-  return *isolate->factory()->NewJSArrayWithElements(details);
+  return MaterializeScopeDetails(isolate, &it);
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugPrintScopes) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 0);
 
 #ifdef DEBUG
   // Print the scopes for the top frame.
   StackFrameLocator locator;
@@ skipping 2032 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal