harmony_scoping: Implement lexical bindings at top level

src/contexts.h

Index: src/contexts.h
diff --git a/src/contexts.h b/src/contexts.h
index dc77861b2578be34e1169ae932c50554adfbfa76..845d7ca660fcda6b37c84189464025eda2378d74 100644
--- a/src/contexts.h
+++ b/src/contexts.h
@@ -183,7 +183,39 @@ enum BindingFlags {
   V(SET_ITERATOR_MAP_INDEX, Map, set_iterator_map)                             \
   V(ITERATOR_SYMBOL_INDEX, Symbol, iterator_symbol)                            \
   V(UNSCOPABLES_SYMBOL_INDEX, Symbol, unscopables_symbol)                      \
-  V(ARRAY_VALUES_ITERATOR_INDEX, JSFunction, array_values_iterator)
+  V(ARRAY_VALUES_ITERATOR_INDEX, JSFunction, array_values_iterator)            \
+  V(GLOBAL_CONTEXT_TABLE_INDEX, GlobalContextTable, global_context_table)
+
+
+class GlobalContextTable : public FixedArray {
+ public:
+  // Conversions.
+  static GlobalContextTable* cast(Object* context) {
+    DCHECK(context->IsGlobalContextTable());
+    return reinterpret_cast<GlobalContextTable*>(context);
+  }
+
+  struct LookupResult {
+    int context_index_;

[rossberg, 2014/11/06 12:29:12]

Nit: public data fields don't have a trailing "_".

[Dmitry Lomov (no reviews), 2014/11/06 17:26:58]

Done.

+    int slot_index_;
+    VariableMode mode_;
+    InitializationFlag init_flag_;
+    MaybeAssignedFlag maybe_assigned_flag_;

[rossberg, 2014/11/06 12:29:12]

Do we actually need the two flags for the global context table?

[Dmitry Lomov (no reviews), 2014/11/06 17:26:58]

They are used in Context::Lookup.

+  };
+
+  int size() const { return length() - 1; }
+
+  static Handle<Context> GetContext(Handle<GlobalContextTable> table, int i) {
+    return Handle<Context>::cast(FixedArray::get(table, i));
+  }
+
+  static bool Lookup(Handle<GlobalContextTable> table, Handle<String> name,
+                     LookupResult* result);
+
+  // table may be null.
+  static Handle<GlobalContextTable> Extend(Handle<GlobalContextTable> table,
+                                           Handle<Context> global_context);
+};
 
 // JSFunctions are pairs (context, function code), sometimes also called
 // closures. A Context object is used to represent function contexts and
@@ -360,6 +392,7 @@ class Context: public FixedArray {
     ITERATOR_SYMBOL_INDEX,
     UNSCOPABLES_SYMBOL_INDEX,
     ARRAY_VALUES_ITERATOR_INDEX,
+    GLOBAL_CONTEXT_TABLE_INDEX,
 
     // Properties from here are treated as weak references by the full GC.
     // Scavenge treats them as strong references.
@@ -555,7 +588,6 @@ class Context: public FixedArray {
   STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
   STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
 };
-
 } }  // namespace v8::internal
 
 #endif  // V8_CONTEXTS_H_